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CEPHALOMETRIC ASSESSMENT OF CLASS II NON-EXTRACTION PATIENTS TREATED WITH THE FORSUS™ FATIGUE RESISTANT DEVICE COMPARED TO INTERMAXILLARY ELASTICS Graham Jones, D.D.S. An Abstract Presented to the Faculty of the Graduate School of Saint Louis University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Dentistry 2007 Abstract Introduction: The Forsus™ Fatigue Resistant Device (FRD) was tested as a compliance-free alternative to Class II elastics. Methods: A sample of 34 (14 females, 20 males) consecutively treated non-extraction FRD patients ages 9 years, 0 months to 17 years, 0 months were matched with a sample of 34 (14 females, 20 males) consecutively treated non-extraction Class II elastics patients ages 9 years, 0 months to 17 years, 0 months based on four pretreatment variables (ANB, L1-GoMe, SN-GoMe, and treatment duration). Pre- and post-treatment cephalometric radiographs were traced and analyzed using the pitchfork analysis and a vertical cephalometric analysis. T-tests were used to evaluate differences between groups. Results: No statistically significant differences were found in the treatment changes between the groups. There was a general trend for mesial movement of the maxilla, mandible, and dentition during treatment for both groups. The mandibular skeletal advancement and dental movements were greater than those in the maxilla, which accounted for the Class II correction. groups. Lower incisor proclination was seen in both Vertically, both the maxillary and mandibular molars exhibited eruption during treatment in both groups, 1 while lower incisor proclined with the incisal edge moving closer to the lower border of the mandible. Conclusions: The Forsus™ FRD is an acceptable substitute for Class II elastics for patients who appear to be non-compliant. Greater forward displacement of the mandible compared to the maxilla was the predominant factor in successfully treated Class II patients with both Class II elastics and the Forsus™ FRD appliance. 2 COMMITTEE IN CHARGE OF CANDIDACY: Adjunct Professor Peter H. Buschang, Chairperson and Advisor Assistant Professor Ki Beom Kim, Assistant Professor Donald R. Oliver i Dedication I dedicate this project to my beautiful wife Erika, whose love and support made the completion of this project possible. I am grateful for her unwavering devotion and support throughout my education. I also dedicate this to my son, Justus, who brings joy to my life. I express gratitude to my parents for their years of love, support, and guidance throughout my life. ii Acknowledgements I would like to acknowledge the following individuals: Dr. Peter Buschang for chairing my thesis committee. Thank you for your guidance, insights, and time. You have a devotion to learning and knowledge and you have taught me much about myself and the world of scientific research. Dr. Donald Oliver for serving on my thesis committee. It has been a privilege to work with you. I truly appreciate your thought-provoking guidance and close attention to detail, which makes you a great teacher and orthodontist. Dr. Ki Beom Kim for serving on my thesis committee. Thank you for your guidance, insight, and encouragement. iii Table of Contents List of Tables...........................................vi List of Figures.........................................vii CHAPTER 1: INTRODUCTION.......... ........................1 CHAPTER 2: REVIEW OF THE LITERATURE The Class II Patient in Orthodontics.....................5 Class II Inter-arch Correction...........................9 Class II Elastics...................................10 Patient Compliance as a Factor in Treatment.........16 Non-compliance Inter-arch Appliances................18 The Herbst Appliance...........................18 The Mandibular Protraction Appliance...........22 The Mandibular Anterior Repositioning Appliance......................................23 The Saif Spring................................26 The Jasper Jumper..............................27 The Eureka Spring..............................31 The Forsus™ Fatigue Resistant Device...........32 Comparing Class II Elastics with Fixed Inter-arch Appliances.....................38 Summary and Statement of Thesis.........................39 References..............................................46 CHAPTER 3: Abstract................................................51 Introduction............................................52 Materials and Methods...................................56 Sample..............................................56 Data Collection.....................................58 Statistical Methods.................................59 Results.................................................60 Cephalometric Comparison............................60 Pre-treatment..................................60 Post-treatment.................................60 Treatment Changes Measured by Pitchfork.............61 Vertical and Angular Treatment Changes..............62 Discussion..............................................63 Conclusions.............................................70 Acknowledgements........................................70 References..............................................71 iv Figures.................................................75 Tables..................................................77 Vita Auctoris............................................82 v List of Tables Table 2.1: Summary of the inter-maxillary noncompliance appliances.....................42 Table 2.2: Summary of maxillary dental effects of inter-arch appliances.....................43 Table 2.3: Summary of mandibular dental effects of inter-arch appliances.....................44 Table 2.4: Summary of skeletal effects of inter-arch appliances................................45 Table 3.1: Sample Description........................77 Table 3.2: Summary of Cephalometric Landmarks and Definitions...............................78 Table 3.3: Pre-treatment comparison of elastics and Forsus™ groups for matched variables......79 Table 3.4: Pitchfork analysis comparison of treatment changes in elastics and Forsus™ groups....80 Table 3.5: Comparison of pre and post-treatment variables and treatment changes in elastics and Forsus™ groups...............81 vi List of Figures Figure 2.1: Diagram of Forsus FRD in place on a fully banded/bracketed appliance................34 Figure 3.1: Diagram of pitchfork analysis.............75 Figure 3.2: Pitchfork summaries of treatment changes..76 vii Chapter I: Introduction Over the years in orthodontics, numerous techniques and appliances aimed at producing predictable resolution of Class II malocclusions have been introduced. These techniques vary in terms of their approach, complexity, variability, and effectiveness. Not surprisingly many attempts have been made to develop newer appliances with the aim to be more efficient or effective. In the field of healthcare, efficiency can be described as the production of desired results with minimum waste of time, money, effort, or skill.1 Similarly, efficacy can be defined as the extent to which a specific intervention produces a beneficial result under ideal conditions.1 Many techniques used for Class II correction have significant shortcomings. Some of the simplest and, seemingly, most effective techniques rely heavily on patient compliance. Patient cooperation in treatment is highly variable, unpredictable, and appears to be decreasing among American patients. Poor cooperation can lead to poor treatment results and/or increased treatment time. Additional treatment time can be costly to both the orthodontist and the patient. Therefore, a number of appliances have been designed in an attempt to eliminate, 1 or at least reduce, the need for patient compliance during treatment. Non-compliance appliances also have shortcomings. They may be expensive, uncomfortable to the patient, unhygienic, prone to breakage, and they may have unwanted side-effects. As experience and material science progress, advances might be expected to have occurred in the development of Class II correction appliances. However, as new appliances are introduced, they must be thoroughly studied. In order to determine which appliances are most effective and efficient in Class II correction, the practitioner needs to know their dental and skeletal effects. This study was designed to evaluate the effects of the Forsus™ Fatigue Resistant Device (FRD) when compared to the effects of Class II elastics. The Forsus™ FRD is a three- piece, telescoping system which incorporates a superelastic nickel-titanium coil spring. The FRD attaches at the maxillary first molar and on the mandibular archwire, distal to either the canine or first premolar bracket. As the coil is compressed, opposing forces are transmitted to the sites of attachment. The properties of the spring, theoretically, allow it to maintain a continuous force without the possibility of fatigue. Fatigue in this case can be described as a fracture caused by repeated 2 application of stresses in the coil spring. The result of the forces produced by this device should serve to correct Class II malocclusions. The skeletal and dental effects that are produced during Class II correction with this device will be measured and compared to the effects of Class II elastics. Class II elastics were chosen as the cooperation group because it represents a typical compliance-reliant method of Class II correction. The purpose of the following review is to describe the challenge that Class II malocclusions pose to the orthodontist and justify further study of the Forsus FRD as an appropriate appliance in non-compliance situations. The prevalence of Class II malocclusion in America and American orthodontic practices will first be presented in order to establish the significance of the Class II problem in orthodontics. Next, a review of the effects of Class II elastics will be offered as a baseline to compare other interarch appliances to. The issue of compliance and the sequelae of failure to comply with orthodontic instructions will be examined as a justification for non-compliance alternatives. A review of the history of non-compliance appliances will follow, in order to fully compare their design, benefits, and problems. Finally, a description of the Forsus FRD and its potential benefits will be presented 3 in addition to a description of previous findings as relate to this appliance. It will be established that the Forsus FRD is a viable, albeit not well researched, option in noncompliance Class II correction. 4 Chapter II: Review of the Literature The Class II Patient in Orthodontics The patient presenting with a Class II malocclusion poses a significant problem in orthodontics in terms of both the scope and the nature of the problem. From 1989 to 1994 the National Health and Nutrition Estimates Survey III (NHANES III) studied approximately 14,000 individuals and was statistically designed to provide estimates of approximately 150 million individuals of various racial and ethnic groups. The NHANES III data provides the best set data regarding malocclusion in children and adults in America. According to NHANES III data, Class II malocclusion (as based on overjet measurements greater than 4 mm) is present in approximately 11% of the US population and comprises approximately one-fifth of all malocclusions.2 Prevalence of this relationship is 10.1% in whites, 11.8% of blacks, and 6.5% of Hispanics. This data also suggests that the skeletal Class II pattern is the most common skeletal disharmony among children and adults. Data collected from 1966 to 1970 for the United Sates National Health Survey suggest an even greater problem. 5 According to the study, which evaluated buccal segment relationship rather than overjet, distoclusion was present bilaterally in 16% of white youths and 6% of black youths age twelve to seventeen.3 When unilateral distoclusion subjects were included, the prevalence was 32% for Caucasians and 18% for African Americans. Distoclusion was described as a situation where the lower molars occlude with the upper molars in a location behind the normal position3. This categorization uses Angle’s definition of Class II malocclusion.4 A study of occlusal relations reported in 1970 found that 16.5% of Caucasian American children ages ten through twelve had bilateral Class II malocclusion and 17.1% had unilateral Class II malocclusion, for a total of 33.6% with at least one side showing a Class II molar relationship.5 The same study found that 11.4% of African American children within the same age range had a lower incidence of Class II relationships, 7.6% bilateral and 3.8% unilateral. Patients with Class II dental relationships often have a corresponding skeletal disharmony. Milacic and Markovic examined the dental casts and cephalometric radiographs of 585 orthodontic patients and found that 51% of the patients who had a Class II Angle relationship had a corresponding Class II skeletal relationship.6 6 A Class II skeletal relationship was classified as one having an ANB angle of 3 degrees or greater. Beresford studied the occlusions and skeletal relationships of 2000 patients aged six to eight-teen.7 According to his data, 73.7 percent of Angle Class II, division 1 patients had a class II skeletal relationship. Additionally, 56.7 percent of Angle Class II, division 2 patients possessed a Class II skeletal relationship. It should be noted that the skeletal classification was determined clinically, not radiographically for this sample. The development of Class II malocclusion is complex and multifaceted. An array of skeletal and dental traits can contribute in various ways to its development. McNamara reviewed previous studies and evaluated the characteristics of 277 children, eight to ten years of age, with Class II dental relations.8 The review showed that previous reports had found the maxilla to be retrusive, normal, or protrusive, depending on the study. Similarly, the maxillary dentition had been reported to be normally positioned or protrusive in Class II subjects. The mandible and/or mandibular dentition had been found to be either normally positioned or retrusive. 7 Finally, there had been a component of vertical excess reported as an important characteristic in many Class II subjects. McNamara’s sample of Class II children revealed that 77 different combinations of morphological characteristics (maxillary skeletal position, maxillary dental position, mandibular skeletal position, mandibular dental position, and vertical dimension) exist which contribute to the development of the problem. Most commonly, the Class II patients had retrusive mandibular skeletal position, neutral maxillary and mandibular dental positions, and excess vertical development. Although the most common, this combination accounted for only 10% of the sample. Maxillary skeletal protrusion was rare. The author concluded that the Class II problem is multi-factorial and often includes mandibular skeletal retrusion and excess vertical development as the most important features. Buschang and Martin longitudinally evaluated growth in 49 females and 50 males.9 This cephalometric report provided the only published assessment of growth from childhood through adolescence. Vertical and anteroposterior skeletal relationships were evaluated from age six to fifteen in Class I and Class II subjects. While anteroposterior relationships (horizontal distance from ANS to Pogonion) generally improved during childhood, they 8 tended to worsen during adolescence. These changes were primarily due to differences in horizontal growth of the mandible. Vertical skeletal changes, measured as the vertical difference between Gonion and Pogonion, increased in the majority of the subjects. While an association between vertical and anteroposterior changes was found, the correlation was not strong. Class II Inter-arch Correction Currently, orthodontists have several methods at their disposal to correct Class II malocclusions. These include fixed or removable intra-arch appliances, fixed or removable inter-arch appliances, selective extraction pattern, and surgical repositioning of one or both jaws. Class II elastics are a typical inter-arch method used for correction, but rely heavily on patient compliance for their effectiveness. Compliance in orthodontics is variable and difficult to predict, therefore, a number of compliance-free inter-arch appliances have been developed. The effects of compliance-reliant Class II elastics will first be reviewed, followed by a review of the problems with compliance in orthodontics. Next, a number of non- compliant orthodontic appliances will be reviewed. The published reports of their effects will be reviewed, and 9 the advantages and disadvantages of each appliance will be presented. The Forsus™ FRD will be described and its potential benefits compared to the other non-compliance appliances will be discussed. Finally, the only published report where the effects of a non-compliance appliance were compared to the effects of Class II elastics will be reviewed in order to justify the need for greater investigation in this field. Class II Elastics The effects that Class II elastics typically produce have been well described. Ellen et al. found that Class II patients treated with Class II elastics and standard edgewise orthodontics without headgear display mesial movement of 4.1 mm and extrusion of 4.0 mm of the mandibular molars.10 The mandibular incisors were proclined 7.9 degrees. The maxillary incisors were extruded 3.7 mm and retroclined 1.4 degrees. A 0.8 degree clockwise rotation of the occlusal plane occurred and the lower facial height increased 6.2 mm. Pogonion and B-point moved forward 1.6 mm and 1.1 mm, respectively. Nelson et al. reported similar findings in a study of patients treated with Class II elastics and Begg orthodontics.11 Patients experienced 1.0 mm mesial growth 10 of the maxilla and 2.1 mm of mesial mandibular displacement. The incisal edge of the maxillary incisors moved distally 3.7 mm, while the incisal edge of the mandibular incisors moved mesially 1.0 mm. overjet decreased 5.8 mm. As a result, Maxillary molars did not experience significant movement, while mandibular molars moved mesially 2.0 mm. The resulting molar correction was 3.0 mm. A later study by Nelson et al. again examined patients treated with Begg appliances and Class II elastics.12 These patients experienced 5.1 mm distal movement of the maxillary incisors and 1.4 mm of mesial movement of the lower incisors. Overjet was reduced 6.7 mm and lower face height increased 4.2 mm. The maxilla and mandible both experienced mesial movement during treatment, 1.3 mm and 1.6 mm, respectively. A 1.3 degree increase in the mandibular plane angle was also noted. Gianelly et al. evaluated Class II patients treated with Class II elastics and either Begg or edgewise appliances.13 He showed that both edgewise and Begg groups showed advancement of pogonion, 2.1mm and 1.6mm, respectively. SNA decreased in both groups (1.5 degrees edgewise, 0.4 degrees Begg), while SNB increased 0.3 degrees in both groups. Clockwise rotation of the 11 mandibular plane occurred in both groups (0.6 degrees edgewise, 1.3 degrees Begg). Finally, an increase in mandibular size was found in both groups (2.7 mm edgewise, 2.9 mm Begg); this was attributed to normal growth. The differences between the two groups were not statistically significant. Tovstein summarized the effects that Class II elastics have on the occlusal plane in patients who exhibited varying amounts of growth.14 While the occlusal plane angle invariably increased during treatment, the increases were less in patients who exhibited more growth and greater in patients who grew less. Furthermore, the occlusal plane angle tended to return toward its previous inclination after treatment in patients who grew more, but exhibited little post-treatment change in patients who grew less. Finally, he found that the changes in A- and B-points were greater in the patients who exhibited the most growth, suggesting that growth is an important factor in the skeletal correction of Class II patients. Hanes examined 38 Class II subjects who had Class II elastics as the only mechanical strategy for Class II correction.15 He found that the majority of the skeletal correction came from posterior movements of A-point, rather than anterior movements of B-point. 12 His subjects displayed an average 2.5 mm posterior movement of A-point and a 0.9 mm posterior movement of B-point. This posterior displacement of B-point was due to a tendency for the mandibular plane angle to increase an average of 0.8 degrees as the mandible rotated clockwise. increased an average of 4.0 mm. Facial height Hanes found that the posterior displacement of B-point was less in the group treated with maxillary elastics than in a similar group treated with cervical headgear.15 He concluded that, typically, Class II elastics did not make the chin more prominent in profile. Bein discussed the theoretical forces that interact in the dentition with the use of Class II elastics.16 His calculations were based on average tooth sizes, inter-arch distances, and typical elastic configurations. When the theoretical force vectors of four-ounce elastics were analyzed, there was a 2.6 ounce extrusive force on the lower molars, in addition to a 3.9 ounce mesial driving force. Furthermore, there was a tendency for distal rotation of the mandibular molar roots and mesial rotation of the maxillary molar roots, as the forces of the elastics were transmitted through these teeth. Zingeser, who evaluated vertical changes associated with Class II elastic treatment, found a pronounced 13 vertical development of the mandibular dento-alveolus and slight vertical development of the maxillary dentoalveolus.17 These vertical increases did not have a significant effect on the mandibular plane due to the concomitant counterclockwise rotation of the mandible that normally occurs with growth, which tended to close the mandibular plane. Adams et al. experimentally studied the skeletal effects of intermaxillary elastics placed in seven Macaca Mulata monkeys.18 Cast splints were made to reduce the amount of tooth movements, and forces ranging from 75 to 250 grams were applied. Metallic bone markers and histological markers were used to track the skeletal effects. Among the changes noted was a backward and downward rotation of the maxilla. The maxillary dentition, including the second molars which were not included in the splint, moved distally. Areas of compression were found between the maxillary tuberosity and the pterygoid process. The mandible moved forward and rotated clockwise. These changes served to rotate the occlusal plane clockwise. Animals in the mixed dentition showed increased bone apposition in the posterior aspect of the mandibular condyle. Minimal or no changes were seen in the condyles of the adult animals, although one adult experienced 14 pathologic resorption in the articular eminence of the temporal bone, due to continuous compression of the joint. Although various combinations of most of these effects serve to correct Class II malocclusions, some of the individual effects are considered undesirable in terms of their result on facial esthetics. For instance, clockwise rotation of the occlusal plane can exaggerate the skeletal appearance of the Class II relationship.11 This is important because clockwise rotation appears to be a commonly reported effect of class II elastics.10,11,19 Kanter composed a list of adverse changes that may occur with the use of elastics in Class II patients, including mesial rotations of the mandibular molar crowns, steepening of the occlusal plane, excessive labial inclination of the mandibular incisors, and anterior displacement of the entire mandibular dental arch.20 The unwanted side-effect of lower incisor proclination is also commonly produced with the use of Class II elastics. This movement is generally regarded as being unstable and, therefore, undesirable.21 In spite of the undesirable side effects produced, intermaxillary elastics can serve as a relatively inexpensive and effective means to treat a Class II malocclusion. 15 Patient Compliance as a Factor in Treatment A major determining factor in the success of Class II elastics during treatment is the willingness of the patient to wear the elastics. The effectiveness of elastics is nearly entirely dependent on patient compliance. Patient compliance with a number of prescribed aspects of treatment has been described as the major limiting factor in orthodontic treatment.22 Shia examined 500 consecutive cases treated in his office.23 He found that patient cooperation was the single factor most likely to lengthen treatment time. Skidmore et al. isolated nine factors that accounted for 38% of the variation in treatment duration.24 factors, three were related to patient compliance. Of these One of the factors that significantly contributed to increased treatment duration was poor elastic wear. Egolf et al. found that some of the factors that were related to lack of compliance with headgear and Class II elastics were personal and short-lived.25 These short-lived factors included disrupting personal events and social pressures. Subjective and unexpected events were difficult to predict and could extend treatment time if the treatment plan was predicated on an assessment of the patient being relatively compliant. 16 Patients may falsely report compliance or incorrectly perceive that compliance has occurred. Brandao et al. instructed patients to wear headgear 14 hours per day.26 The amount of wear was recorded by the patients and, unknown to the patients, monitored via a time recording device within the headgear. Although patients reported themselves to be relatively compliant (with 13.6 hours of headgear wear per day), the recordings revealed that compliance was poor (5.6 hours per day). Even after the patients were told they were being monitored, compliance only rose slightly (6.7 hours per day). These findings suggest that compliance was generally poor (less than half of what was asked) and either misperceived or falsely reported. Patient compliance may be difficult to predict because it is a complex psychosocial construct. El-Mangoury noted that patients who are good cooperators in some aspects, such as oral hygiene may not necessarily be good cooperators with elastic and headgear wear.27 The problem is significant enough to warrant the development of several “non-compliance” appliances. These appliances, when compared to standard treatment using Class II elastics, can be more expensive, but their cost has been justified by the 17 notion that they can reduce treatment time while achieving similar results. Non-compliance Inter-arch Appliances There are numerous examples in the orthodontic literature of attempts to create an ideal Class II correction appliance. removable. Initially, these appliances were As the demand for compliance-free appliances increased, some of the designs were altered so that the removable appliances could be fixed in place. The Herbst Appliance The first and best established fixed Class II correction appliance is the Herbst appliance. Originally designed as a removable appliance in 1909 by Emil Herbst, a fixed version for sagittal orthodontic correction was subsequently introduced and reports of its effects were published in 1934.28 In 1979 Pancherz re-introduced the Herbst appliance in the orthodontic literature.29 The Herbst appliance is comprised of a plunger housed within a tube. The tube is typically attached to the maxillary first molar on each side and the plunger is attached to the mandibular dentition. Methods of attachment include banded, crowned, 18 and acrylic splinted versions. The splinted Herbst is now advocated by Pancherz as the preferred device.30 This design incorporates cast splints that cover the maxillary and mandibular molars and premolars and can include the canines and anterior teeth. The anterior teeth can have brackets placed which, in turn, can be ligated to the splint. In this way more teeth are included as anchorage. This version is believed to be more hygienic, better fitting, stronger, and less likely to require replacement of bands over time. The Herbst is typically used during the initial six to eight months prior to full edgewise orthodontic treatment.30 Although attempts have been made to incorporate the Herbst into a single phase along with fixed appliances, bracketing of mandibular canines and premolars is not possible in conjunction with Herbst use. In 1997, Pancherz reviewed the effects of Herbst treatment.30 Effects included discernible mandibular morphological changes and increased sagittal condylar growth during treatment. Effects described in the maxillary complex of 45 Herbst subjects were similar to those expected with high-pull headgear. The upper molars were intruded in 69% of the subjects (with a maximum value of 3.5 mm of intrusion) and pushed distal in 96% of subjects (with a maximum of 4.5 mm). 19 The occlusal plane tipped downward up to a maximum of 7.5 degrees in 82% of cases. Overbite correction occurred due to eruption of the mandibular molars, as well as intrusion and proclination of the mandibular incisors. These effects were largely beneficial and comparable to the effects obtained in a compliant patient wearing elastics and headgear. A significant drawback of the Herbst appliance is its tendency to procline the mandibular incisors.30,31 Whether the banded, crowned, or splinted version is used, this effect is difficult to control. shown to be a problem. Stability has also been Post-treatment, it has been shown that most of the mandibular morphological changes revert, resulting in no long-term differences in mandibular growth between patients treated with a Herbst and untreated patients.30 The headgear effect appears to be fleeting as well, as the maxillary molars extrude and move mesially. The relapse of changes due to Herbst treatment all took place within six months of appliance removal.30 In order to maintain the benefits of the Herbst appliance, Pancherz recommends finishing the patient with stable cuspal interdigitations.30 In order to achieve this, treatment in the mixed dentition should be avoided; rather treatment should be reserved for the permanent dentition just after the peak of pubertal growth.30 20 A report by Valant and Sinclair described the effects of a splinted Herbst appliance in 32 consecutively treated patients.31 According to this report, the Herbst exhibited a slight headgear effect that served to decrease the SNA angle 0.7 degrees, compared to a very slight increase of this angle in a control group. was more pronounced. The effect on the mandible A net 3.3 mm total mandibular length increase in the Herbst group proved to be 1.3 mm greater than the control group over the same time period. Facial height increased more in the Herbst group during treatment than in the control group. While maxillary incisors showed minimal change, the mandibular incisors flared more during Herbst treatment, even with the lower occlusal splint. The IMPA increased 2.4 degrees in the Herbst group and 0.4 degrees in the control group. The Herbst group also showed less vertical maxillary molar development (0.1 mm) during treatment, compared to the control group (1.0 mm). Maxillary molar movement was 1.5 mm in a distal direction, with 6.4 degrees of distal crown tipping. The mandibular molars moved mesially 1.6 mm with no tipping. Benefits of the Herbst include its effectiveness of correcting Class II relationships and its non-compliance nature. Breakage, relapse of treatment results, potential causation of a dual bite, cost of fabrication, and the need 21 for several initial appointments have plagued the Herbst appliance. The Mandibular Protraction Appliance (MPA) The Mandibular Protraction Appliance (MPA) was developed in 1995 as a less complicated and less expensive alternative to the Herbst appliance.32 The original design consisted of a set of in interlocking 0.032 inch stainless steel wires that were intended to force the patient’s mandible to be positioned forward. A coiled spring was also included in the device to prevent the wires from interlocking. If the patient attempts to force the mandible into a retruded position, resistance in the appliance is translated as a push force against the maxillary molars and mandibular canines.32 Since its inception, the MPA has undergone several transformations. The most recent design more closely resembles the Herbst appliance and consists of a 0.40 inch primary tube that rests within a 0.045 inch tube. The primary tube is threaded into a loop on a lower 0.019 x 0.025 inch stainless steel mandibular archwire. Theoretically, the MPA produces a set of forces similar to the Herbst appliance. While no studies have been published describing the actual effects of the MPA, case reports suggest that it 22 can be an effective device in correcting Class II malocclusions in both adolescents and adults.33 The advantages of the MPA are its simple, chair-side fabrication, reduced cost, non-compliance nature, and its ability to be used in conjunction with nearly full, fixed orthodontic appliances (the mandibular premolars cannot be bonded). The disadvantage of this device stems from its non-rigid construction. Breakage and distortion of the device are very likely because the diameter of stainless steel wire used is neither rigid enough to resist distortion, nor flexible enough to return to its predeformed state. The Mandibular Anterior Repositioning Appliance (MARA) The Mandibular Anterior Repositioning Appliance (MARA) was introduced in 1998. It was designed to encourage patients to maintain their mandible in a forward position by incorporating areas of occlusal interference. Heavy 0.060 inch square steel bars run vertically from crowns cemented on the maxillary molars and contact a second set of 0.059 inch steel bars positioned horizontally on mandibular molar crowns. Additional advancements can be accomplished with the addition of shim stocks. As the mandible is positioned forward there is the theoretic 23 potential for “growth stimulation” at the mandibular condyle, similar to the effects hoped for when a removable functional appliance is prescribed. Additionally, as the patient attempts to position the mandible posteriorly, push forces are exerted distally against the maxillary molars and mesially against the mandibular molars. These forces assist with the correction of Class II dental relationships. Based on cephalometric radiographs, Pangrazio-Kolbersh et al. demonstrated the effects of the MARA on 12 boys and 18 girls (compared to a control group of twenty-one untreated Class II subjects).34 Eruption of the molars was assessed by measuring vertically from the Frankfort Horizontal plane to the occlusal plane. The maxillary molars showed less eruption in the MARA group than in the control group, at 0.1 mm per year compared to 0.9 mm of eruption per year respectively. Sagittal molar movements were evaluated by measuring the distance from a vertical reference line drawn perpendicular to Frankfort Horizontal. The MARA group displayed an average of 1.1 mm distal movement of the maxillary molars compared to a 1.3 mm mesial movement of the maxillary molars in the control group. The mandibular molars moved mesially 1.2 mm on average in the MARA group, while the control group showed 24 only 0.5 mm mesial movement. The mandibular incisor moved mesially 0.6 mm and the IMPA increased 3.9 degrees per year in the MARA group, compared to 0.4 mm of distal movement and a 0.3 degree IMPA increase in the control group. The MARA group showed greater increase in mandibular length, as measured from condylion to gnathion, than the control group. The increases were 4.8 mm and 2.1 mm, respectively. Anterior and posterior facial heights increased more in the MARA group than in the control group. Finally, the occlusal plane angle increased 0.4 degrees and decreased 0.9 degrees in the MARA and control groups, respectively. The effects of the MARA appear to be very similar to those produced by the Herbst appliance, but with less headgear effect on the maxilla and less mandibular incisor proclination. An advantage of the MARA is that full fixed orthodontic appliances may be placed along with the MARA, therefore reducing or eliminating the need for 2-phases of treatment. Allowing the MARA to remain in place following Class II correction while fixed orthodontic treatment is being performed may offer improvements in long term stability. Disadvantages of the MARA are related to the necessity of stainless steel crown fabrication in order to accommodate the appliance. The crowns take additional time 25 and expense at a commercial laboratory. The crowns can also increase anterior face height slightly. Because of the time and additional appointments necessary for fabrication, the MARA may not be a desirable mid-treatment alternative for patients who cooperate poorly with Class II elastic wear. Like the other appliances reviewed, breakage and the time and cost associated with repair pose significant problems for its clinical application. The Saif Spring The Saif Spring was introduced in the late 1960s as a fixed alternative to Class II elastics. This nickel- titanium spring system produces the same force vector as Class II elastics. It was designed to deliver 200-400 grams (approximately 6 to 13 ounces) of force. The low end of this range of force is comparable to medium to heavy elastics, and the high end may exceed the force recommended for elastic use. Breakage is a problem with this device. It must also be replaced at varying intervals by the orthodontist as the spring fatigues. No data have been presented to describe the actual effects of the Saif Spring.35 26 The Jasper Jumper The Jasper Jumper was introduced in 1994 as a fixed Class II corrector that can be used in conjunction with fixed appliances. The Jasper Jumper consists of two vinyl coated springs resting in the buccal sulcus. This appliance exerts different forces than Class II elastics; it produces a distal and intrusive force against the maxillary molar and a mesial and intrusive force against the mandibular canine. Cope et al. characterized the dental and skeletal effects produced by the Jasper Jumper in 31 Class II patients compared to a control group of Class II adolescents. The Jasper Jumper had a posterior repositioning effect on the maxilla.36 ANS moved posteriorly 0.9 mm per year and A-point was moved posteriorly 0.6 mm per year. There was no evidence of increased condylar growth of the mandible with the Jasper Jumper, although there was more clockwise mandibular rotation produced than in the untreated control group. Dentally, the Jasper Jumper moved both the upper incisors and molars distally, 4.7 and 4.3 mm per year, respectively. Compared to controls the Jasper Jumper group also showed extrusion of the maxillary incisors and a tendency to prevent eruption of the maxillary molars. The mandibular incisors displayed uncontrolled tipping, with the tip of 27 the incisor moving mesially 4.4 mm per year, and intruding at a rate of 1.7 mm per year. The lower molar moved forward 3.8 mm by a combination of tipping and bodily movements. The lower molars were also extruded. The net effects of the Jasper Jumper were distal maxillary skeletal and dental movements, mesial mandibular dental movements due mostly to tipping, no additional mandibular growth over control, and clockwise mandibular rotation. Weiland and Bantleon published a report of seventeen consecutively treated Jasper Jumper patients.37 When compared to normal development, represented by the Bolton standards, the Jasper Jumper patients showed slight restriction of antero-posterior maxillary growth, 2.4 mm more distal movement of the upper incisors, 0.8 mm more mesial movement of the mandibular incisors, 1.6 mm more mesial movement of the mandibular molar. A 3.2 degree clockwise rotation of the occlusal plane and 1.6 mm advancement of Pogonion were found in the Jasper Jumper group, which compared with 0.1° of counterclockwise rotation and 0.8 mm of advancement in the control group. The modest amount of increased mandibular length was attributed to changes in the condyle-fossa relationship in the temporal-mandibular joint. 28 The authors concluded the net correction of the Class II malocclusion was 60% dental and 40% skeletal. A study by Stucki and Ingervall examined 26 patients who had undergone Jasper Jumper treatment.38 Their findings showed a 0.6 degree decrease in SNA, 0.8 degree increase in SNB, and a 4.7 mm decrease in overjet. Contrary to Cope, et al.36, but in accordance with Weiland and Bantleon, they reported an increase in mandibular length.37 The distance of Pogonion to OLp (a line drawn from Sella, perpendicular to the occlusal plane) distance increased 1.6 mm during treatment. Additionally, upper incisors were retroclined 1.6 mm and extruded 0.6 mm, the lower incisors were proclined 6.4 degrees, lower molars moved mesially 2.6 mm and extruded 0.7 mm, and the upper molars moved distally 0.9 mm and intruded 0.6 mm. Contrary to the previously described findings, the anterior face height was decreased 1.1 mm during treatment and the mandibular plane rotated counterclockwise 1.2 degrees. No mention of occlusal plane behavior was made. Importantly, the patients treated with the Jasper Jumper were not compared to untreated controls, making it difficult to distinguish between the growth and treatment effects. Covell et al. examined 36 growing Class II patients treated with the Jasper Jumper and fixed edgewise 29 treatment.39 These patients were compared to a control group of untreated Class II patients. The Jasper Jumper group showed a significant reduction in the SNA angle (-1.6 degrees compared to +0.3 degrees in the controls), a 0.6 degree clockwise rotation of the occlusal plane (compared to 1.4 degrees counterclockwise rotation in controls), and a 5.3 degree increase in IMPA (compared with a 1.0 degree decrease in controls). and tipped distally. The maxillary molars were intruded Additionally, Jasper Jumper treated patients experienced 2.6 mm forward (which was not compared to control) and 0.9 mm extrusive movements of the mandibular molars (compared to 0.4 mm in control). No significant changes in the mandibular plane angle or horizontal mandibular growth were noted. These findings, with the exception of the lack of change in mandibular plane angle, are in accordance with those of Cope et al.36 Both studies, which used appropriate controls, failed to find the additional mandibular growth that was reported by Weiland and Bantleon and Stucki and Ingervall whose conclusions were drawn without the use of appropriate controls.37,38 Covell et al. suggest that the differences in mandibular length found between these studies may be due to variations in superimposition technique.39 30 A forward posture of the mandible may be misinterpreted as an increase in mandibular length when using cranial superimposition techniques. Cope et al. and Covell et al. who used separate cranial base, maxillary, and mandibular structural superimpositions, found no increases in mandibular length.36,39 Weiland and Bantleon, who reported increased mandibular length, used only a cranial base superimposition.37 The disadvantages of the Jasper Jumper include the side effect of incisor proclination and the large inventory of appliances required to accommodate the variety of patients seen in a typical orthodontic practice. breakage is also a problem. Appliance Other appliances, including the Adjustable Bite Corrector, the Bite Fixer, and the Klapper Superspring, are variations of the Jasper Jumper design and might be expected to produce similar results. The Eureka Spring In 1996 the Eureka spring was introduced as a fixed intra-arch Class II appliance. It boasts better inventory control and less breakage than the Jasper Jumper.40 The design of the appliance incorporates an open coil spring within a telescoping plunger assembly. Because of the telescoping aspect of the appliance, the mandible is 31 allowed to open up to 60 millimeters before the assembly disengages. This is a significant benefit over several other, more rigid appliances which restrict mandibular movement.40 A study of 37 consecutive patients treated with the Eureka spring to correct Class II malocclusions described the dental and skeletal effects.41 compared to any control group. These effects were not The maxillary incisors were retroclined 2.9 degrees. The mandibular incisors did not experience any change in angulation, but moved mesially 1 mm. The occlusal plane rotated clockwise 2.3 degrees. The maxillary molars moved distally 1.2 mm and intruded 0.9 mm. The mandibular molars moved mesially 1.5 mm. No significant skeletal effects were produced. The Forsus™ Fatigue Resistant Device Recently, an innovative non-compliance appliance has been developed to remedy some of the shortcomings that have plagued previous appliances. The Forsus™ Fatigue Resistant Device (FRD) consists of a three piece, telescoping nickeltitanium spring that is attached to the headgear tube of the maxillary molar band via an L-pin (See Figure 2.1). The spring assembly is connected to the mandibular arch by a push-rod, which attaches directly onto the mandibular 32 archwire either distal to the canine bracket or distal to the first premolar bracket. The FRD offers some advantages over earlier non-compliance appliances. First, it may be assembled chair-side in a relatively short amount of time because the device consists of only three parts. Second, the FRD is completely compatible with complete fixed orthodontic appliances. In contrast to other non- compliance appliances, the FRD can be fabricated and incorporated into the orthodontist’s pre-existing appliance, with the only stipulation being that the maxillary molar bands have headgear tubes. crown fabrication is necessary. No additional This feature provides the orthodontist a range of adaptability in treatment because the FRD can be added to or removed from the patient’s full appliances at any time. In this manner, like the Saif Spring, the FRD offers Class II correction alternative that can be installed immediately for non-compliant patients. Another potential positive result of this feature is that the orthodontist can engage a full-sized wire into the anterior brackets in an attempt to control the amount of incisor tipping that takes place due to the Class II corrective forces. Finally, the manufacturer claims that the FRD may be less prone to breakage than other appliances. The direct push-rod offers rigidity at the 33 point of attachment, while the fatigue-resistant spring provides flexibility that is not possible with appliances such as the Herbst and MARA. Proprietary data suggest that force levels of the spring are maintained at approximately 200 grams (equivalent to medium Class II elastics).42 If the appliance does experience breakage, the portion that breaks can be replaced during a single appointment. Several other Class II correctors must be completely replaced or repaired in a laboratory if broken. 1 3 2 Figure 2.1: Diagram of Forsus FRD in place on a fully banded/bracketed appliance (modified from 3M) 1. L-pin through maxillary first molar tube titanium spring 3. Push rod 34 2. Nickel- Like other non-compliance appliances, the FRD is not free of drawbacks. Breakage is not eliminated and the spring and push-rod are bulky, with a potential for patient discomfort and soft-tissue injury. The FRD also requires a moderate amount of inventory and additional expense. The design of the Forsus™ FRD represents an improvement of a previous, similar appliance, the Forsus™ Nitinol Flat Spring (NFS). The Forsus™ NFS appliance, designed in 2001, is composed of a set of nickel-titanium bars attached to the first molar bands and the mandibular archwire in the same fashion as the current Forsus™ FRD. However, the first premolar bracket must be removed in order to accommodate the Forsus™ Nitinol Flat Spring. The effects of the Forsus™ NFS appliance were described for a group of 16 Class II, division 1 patients and compared to similar groups of Jasper Jumper patients and untreated controls.43 The authors noted similar skeletal changes in both treated groups. These changes included a decrease in the ANB angle due to retrusion of maxilla and protrusion of the mandible. SNA decreased, while SNB and Condylion-Gnathion increased. Posterior face height (S-Go) was increased and a significant clockwise rotation of the mandible (increase in the y-axis) elongated the anterior facial height. Dental changes included distal 35 movement, intrusion and retroclination of the upper incisors. The upper incisor to Sella-Nasion angle decreased five degrees in both of the treated groups. Intrusion, proclination, and mesial movement of the mandibular incisors were noted. The IMPA increased 4.5 degrees in the Forsus™ NFS group and 6.5 degrees in the Jasper Jumper group, while the lower incisor edge intruded relative to the mandibular border 3 mm and 2.5 mm, respectively. The upper molars were distalized and intruded, while the mandibular molars were moved mesially and extruded. Overjet was decreased 3.7 mm in the Forsus™ NFS group and 3.2 mm in the Jasper Jumper group, no decrease was found in the control group. Overbite was decreased 1 mm in the Forsus™ NFS group and 0.7 mm in the Jasper Jumper group, while the control group did not experience change. The occlusal plane relative to SellaNasion rotated clockwise approximately 2 degrees in each of the treated groups, but did not change in the control group. These authors theorized that mandibular growth is stimulated with both the Forsus™ NFS and the Jasper Jumper. Henig and Göz reported the effects of the Forsus™ NFS on 13 growing Class II subjects.44 No control or comparison groups were used. The subjects’ ages ranged from 12.5 years to 17 years with an average of 14.2 years. 36 The Forsus™ NFS appliance was in place for four months in each subject. Cephalometric radiographs were taken at the times of insertion and removal of the Forsus™ NFS appliances. In this study the SNB increased 0.5 degrees and the occlusal plane rotated clockwise 4.2 degrees. The upper incisors were retroclined 5.3 degrees which contributed to the 1.4 mm distal movement of the upper incisor. The lower incisors were proclined 9.6 degrees, which contributed the 3.3 mm of lower incisor mesial movement observed. Pogonion was repositioned 1.2 mm forward after Forsus™ NFS treatment. The upper molars moved distally 0.8 mm and the lower molars moved mesially 3.1 mm. No other statistically significant treatment changes were reported. The investigators noted widening of both arches based on analyses of the dental casts. Additionally, questionnaires were given to all patients in order to determine the problems that the appliance may pose. The most common problem noted was jaw restriction in yawning. Other problems included limited mouth opening, pain on the inside of the cheeks, difficulty in cleaning the teeth, and change in appearance. The Forsus™ FRD attempts to resolve opening restrictions by introducing a telescoping mechanism. Additionally, the Forsus™ FRD does not require the removal of brackets, unlike the Forsus™ NFS. 37 Comparing Class II Elastics with Fixed Inter-Arch Appliances Only one study has compared the effects of Class II correction obtained with elastics to those obtained with fixed inter-arch appliances. This is significant, as these appliances have the potential to be compliance-free alternatives in instances where a level of patient compliance required for successful treatment is not reached. Although these appliances may achieve a successful result en lieu of Class II elastics, the skeletal and dental changes that they produce may be significantly different from elastics. It is important that these potential differences be identified and understood, so that an appropriate decision can be made in evaluating appliances. Nelson et al. compared non-extraction, Class II patients who had Begg treatment, which includes long-term elastic wear, with patients who had undergone Herbst treatment.12 The samples were matched based on age, malocclusion, and somatic maturation (as assessed by analyzing the distance curve of the standing height). The anterior lower facial height increased more in the Begg group (4.2 mm) than in the Herbst group (3.2 mm). In the Begg group, the mandibular plane angle increased 1.3 38 degrees; this angle remained unchanged in the Herbst group. In the Begg group, the maxilla moved forward 1 mm more than in the Herbst group, while the mandible moved forward 1 mm more in the Herbst group. The maxillo-mandibular skeletal improvements were approximately 2.0 mm greater in the Herbst group than in the Begg group. The overjet reduction was 2.1 mm larger in the Begg group, mostly due to dental movements. While the molar corrections were similar in both groups the skeletal improvement was 10% in the Begg group, compared with 66% in the Herbst group. Comparing the effects of various non-compliance appliances is difficult due to the variation in research protocols. There is no set protocol for patient age, duration of appliance placement, or anchorage preparation for experimental groups. Additionally, the use of different cephalometric evaluations, reference landmarks, and superimposition techniques to measure changes has further confounded the data. This has led to reports that appear to present conflicting data. Summary and Statement of Thesis The Forsus FRD has the potential to be a viable alternative for Class II correction in a non-compliant patient. In order to replace Class II elastics, the FRD 39 should provide similar or improved dental and skeletal effects. A complete investigation into the effects of this device is appropriate and necessary in order to evaluate the viability of the FRD as a compliance-free option to replace Class II elastics. Only one study comparing the effects of Class II elastics to the effects of a compliance-free appliance has been published. If compliance-free appliances are to be used as a substitute in non-compliant patients, more investigation is warranted into the similarities and differences in treatment results with these appliances. The purpose of this investigation is to describe the sagittal and vertical effects that the Forsus Fatigue Resistant Device produces on the maxillary and mandibular dentition, as well as its effects on the maxillary and mandibular apical bases. These changes will be compared to the changes produced by Class II elastics in a similar sample of patients. The effects of this device have yet to be evaluated in the literature. Complete evaluations of new devices and techniques must be carried out in order to provide the practitioner with the data necessary to make informed decisions in treating their patients. Not every patient is capable of or willing to provide the compliance necessary for Class II elastics. 40 In these instances compliance-free appliances, such as the Forsus FRD, may be an appropriate option. By understanding the similarities and/or differences produced by these two methods of Class II treatment, a decision based on objective evidence can be made regarding use of compliance-free appliances as suitable substitutes in non-compliant patients. 41 Table 2.1: Summary of the inter-maxillary non-compliance appliances Appliance Name Indications Design Herbst • Bilateral telescoping mechanism advancing the mandible into new position • • • Jasper JumperTM • • • • • • MARA • • • Saif Springs • Eureka SpringTM • Forsus FRDTM Dental Class II malocclusion Lower incisor advancement Skeletal Class II mandibular deficiency Upper molar distalization Dental Class II malocclusion. Lower incisor advancement Upper molar distalization Open Bites Vertical Growers Minimal vestibular space Dental Class II malocclusion Upper molar distalization Lower incisor advancement Class II traction Dental Class II malocclusion • Upper molar distalization • Lower incisor advancement N/A 42 Inter-maxillary springs in compression Bilateral fitted to stainless crowns to mandible cams molar steel advance Class II coil springs in tension Telescopic rods with integral light force compression springs Intermaxillary Nitinol spring providing reciprocal push forces distally against upper molar and mesially against lower canine or premolar Table 2.2: Summary of maxillary dental effects of interarch appliances. Appliance Method of measurement Max 6 vertical Max 6 sagittal Angular: Measurement of preand post- treatment cephs Linear: Cartesian coordinate system (see figure 2) Angular: measurement of preand post-treatment cephs Linear: Bjork Analysis (See figure 3) 3.0mm 0mm Max 1 vert. 3.69mm Max 1 sag. 1.4º N/A N/A N/A N/A Angular and linear measurements based on pre- and post- treatment cephs using various skeletal landmarks as reference points 0.2mm -1.5mm N/A 0.1º Vertical and sagittal measurements using McNamara technique (See figure 4) 0.1mm -1.1mm N/A N/A Cranial base superimposition to determine skeletal changes, regional superimposition to assess dental changes -1mm -4.3mm 2.5mm -4.7mm Angular: measurement of pre- and post-treatment cephs Linear: Bjork Analysis (See figure 3) N/A -1.4mm N/A -2.4mm Angular: measurement of pre- and post-treatment cephs Linear: Bjork Analysis (See figure 3) 0.6mm 0.9mm 0.6mm -1.6mm Angular and linear measurements based on pre- and post- treatment cephs using various skeletal landmarks as reference points -1.0mm -2.0mm 1.0mm -6.0º /Author Class II Elastics Ellen et al. (1998) Class II Elastics Nelson et al. (1999) Herbst Valant and Sinclair (1989) MARA PangrazioKulbersh et al. (2003) Jasper Jumper Cope, et al. (1994) Jasper Jumper Weiland and Bantleon (1999) Jasper Jumper Stucki and Ingerval (1998) Jasper Jumper Covell et al. (1999) 43 Table 2.3: Summary of mandibular dental effects of interarch appliances. Appliance Method of measurement Mand 6 vertical Mand 6 sagittal Mand 1 vert. Mand 1 sagit. Angular: Measurement of pre- and post- treatment cephs Linear: Cartesian coordinate system (see figure 2) 4.04mm 4.08mm 7.29mm 7.9º Angular: measurement of preand post-treatment cephs Linear: Bjork Analysis (See figure 3) N/A 2mm N/A 1.4mm Angular and linear measurements based on pre- and post- treatment cephs using various skeletal landmarks as reference points 1mm 1.6mm N/A 2.4º Vertical and sagittal measurements using McNamara technique (See figure 4) 1.3mm 1.1mm 0.5mm 3.9º Cranial base superimposition to determine skeletal changes, regional superimposition to assess dental changes Angular: measurement of pre- and post-treatment cephs Linear: Bjork Analysis (See figure 3) 1.52mm 3.8mm -1.7mm 4.4mm N/A 1.6mm N/A 0.8mm Angular: measurement of pre- and post-treatment cephs Linear: Bjork Analysis (See figure 3) 0.7mm 2.6mm N/A 6.4º Angular and linear measurements based on pre- and post- treatment cephs using various skeletal landmarks as reference points 0.9mm 2.8mm -1.0mm 5.3º /Author Class II Elastics Ellen, et al. (1998) Class II Elastics Nelson, et al. (1999) Herbst Valant and Sinclair (1989) MARA PangrazioKulbersh et al. (2003) Jasper Jumper Cope, et al. (1994) Jasper Jumper Weiland and Bantleon (1999) Jasper Jumper Stucki and Ingerval (1998) Jasper Jumper Covell et al. (1999) 44 Table 2.4: Summary of skeletal effects of inter-arch appliances. Appliance /Author Class II Elastics Ellen, et al. (1998) Class II Elastics Nelson, et al. (1999) Herbst Valant and Sinclair (1989) MARA PangrazioKulbersh et al. (2003) Jasper Jumper Cope, et al. (1994) Jasper Jumper Weiland and Bantleon (1999) Jasper Jumper Stucki and Ingerval (1998) Jasper Jumper Covell et al. (1999) Method of measurement A Point B Point Mandib Length Occl Plane Lower Face Height Angular: Measurement of preand post- treatment cephs Linear: Cartesian coordinate system (see figure 2) Angular: measurement of preand post-treatment cephs Linear: Bjork Analysis (See figure 3) -1.7° -0.1° 1.7mm 0.8° 6.2mm -1.0° -0.4° 2.1mm N/A 5.0mm Angular and linear measurements based on pre- and posttreatment cephs using various skeletal reference points -0.7° 1.3mm 3.3mm N/A 4.2mm Vertical and sagittal measurements using McNamara technique (See figure 4) -0.4° 1.1° 4.5mm 0.4° 2.5mm Cranial base superimposition to determine skeletal changes, regional superimposition to assess dental changes Angular: measurement of preand post-treatment cephs Linear: Bjork Analysis (See figure 3) Angular: measurement of preand post-treatment cephs Linear: Bjork Analysis (See figure 3) Angular and linear measurements based on pre- and posttreatment cephs using various skeletal landmarks as reference points -0.6° -0.4° 0mm N/A N/A -0.8° 1.2° 1.6mm N/A N/A -0.6° 0.8° 1.6mm N/A -1.1mm 0.8° 0.3° 0.6 2.4º -0.2mm 45 References 1. Stedman TL. Stedman's medical dictionary. 27th ed. New York: Lippincott, Williams, & Wilkins; 1999. 2. Proffit WR, Fields HW, Jr., Moray LJ. Prevalence of malocclusion and orthodontic treatment need in the United States: estimates from the NHANES III survey. Int J Adult Orthodon Orthognath Surg 1998;13:97-106. 3. Kelly JE, Harvey CR. An assessment of the occlusion of the teeth of youths 12-17 years. Vital Health Stat 11 1977:1-65. 4. Angle EH. Treatment of malocclusion of the teeth. 7th ed. Philadelphia: S.S. White; 1907. 5. Horowitz HS. A study of occlusal relations in 10-12 year old Caucasian and Negro school children--summary report. Int Dent J 1970;20:593-605. 6. Milacic M, Markovic M. A comparative occlusal and cephalometric study of dental and skeletal anteroposterior relationships. Br J Orthod 1983;10:53-54. 7. Beresford RF. Tooth size and Class distinction. Dent Pract Dent Rec 1969;20:113-120. 8. McNamara JA, Jr. Components of class II malocclusion in children 8-10 years of age. Angle Orthod 1981;51:177-202. 9. Buschang PH, Martins J. Childhood and adolescent changes of skeletal relationships. Angle Orthod 1998;68:199-206; discussion 207-198. 10. Ellen EK, Schneider BJ, Sellke T. A comparative study of anchorage in bioprogressive versus standard edgewise treatment in Class II correction with intermaxillary 46 elastic force. Am J Orthod Dentofacial Orthop 1998;114:430436. 11. Nelson B, Hansen K, Hagg U. Overjet reduction and molar correction in fixed appliance treatment of class II, division 1, malocclusions: sagittal and vertical components. Am J Orthod Dentofacial Orthop 1999;115:13-23. 12. Nelson B, Hansen K, Hagg U. Class II correction in patients treated with class II elastics and with fixed functional appliances: a comparative study. Am J Orthod Dentofacial Orthop 2000;118:142-149. 13. Gianelly AA, Arena SA, Bernstein L. A comparison of Class II treatment changes noted with the light wire, edgewise, and Frankel appliances. Am J Orthod 1984;86:269276. 14. Tovstein BC. Behavior of the occlusal plane and related structures in treatment of Class II malocclusions. Angle Orthod 1955;25:189-198. 15. Hanes RA. Bony profile changes resulting from cervical traction compared with those resulting from intermaxillary elastics. Am J Orthod 1959;45:353-364. 16. Bien SM. Analysis of the components of force used to effect distal movement of teeth. Am J Orthod 1951;37:508521. 17. Zingeser M. Vertical response to Class II division 1 therapy. Angle Orthod 1964;34:58-64. 18. Adams CD, Meikle MC, Norwick KW, Turpin DL. Dentofacial remodelling produced by intermaxillary forces in Macaca mulatta. Arch Oral Biol 1972;17:1519-1535. 19. Remmer KR, Mamandras AH, Hunter WS, Way DC. Cephalometric changes associated with treatment using the 47 activator, the Frankel appliance, and the fixed appliance. Am J Orthod 1985;88:363-372. 20. Kanter F. Mandibular anchorage and extraoral force. Am J Orthod 1956;42:194-207. 21. Meikle MC. The dentomaxillary complex and overjet correction in Class II, division 1 malocclusion: objectives of skeletal and alveolar remodeling. Am J Orthod 1980;77:184-197. 22. Beckwith FR, Ackerman RJ, Jr., Cobb CM, Tira DE. An evaluation of factors affecting duration of orthodontic treatment. Am J Orthod Dentofacial Orthop 1999;115:439-447. 23. Shia GJ. Treatment overruns. J Clin Orthod 1986;20:602604. 24. Skidmore KJ, Brook KJ, Thomson WM, Harding WJ. Factors influencing treatment time in orthodontic patients. Am J Orthod Dentofacial Orthop 2006;129:230-238. 25. Egolf RJ, BeGole EA, Upshaw HS. Factors associated with orthodontic patient compliance with intraoral elastic and headgear wear. Am J Orthod Dentofacial Orthop 1990;97:336348. 26. Brandao M, Pinho HS, Urias D. Clinical and quantitative assessment of headgear compliance: a pilot study. Am J Orthod Dentofacial Orthop 2006;129:239-244. 27. El-Mangoury NH. Orthodontic cooperation. Am J Orthod 1981;80:604-622. 28. Herbst E. Dreissigjahrige erfahrungen mit dem retentionsscharnier. Zahnartzl Rundschau 1934;43:1515-1524. 29. Pancherz H. Treatment of class II malocclusions by jumping the bite with the Herbst appliance. A cephalometric investigation. Am J Orthod 1979;76:423-442. 48 30. Pancherz H. The effects, limitations, and long-term dentofacial adaptations to treatment with the Herbst appliance. Semin Orthod 1997;3:232-243. 31. Valant JR, Sinclair PM. Treatment effects of the Herbst appliance. Am J Orthod Dentofacial Orthop 1989;95:138-147. 32. Coelho Fliho CM. Mandibular protraction appliances for Class II treatment. J Clin Orthod 1995;29:319-336. 33. Coelho Fliho CM. Mandibular protraction appliance IV. J Clin Orthod 2001;35:18-24. 34. Pangrazio-Kulbersh V, Berger JL, Chermak R, Simon ES, Haerian A. Treatment effects of anterior repositioning appliance on patients malocclusion. Am J Orthod Dentofacial Orthop 295. DS, Kaczynski the mandibular with Class II 2003;123:286- 35. McSherry PF, Bradley H. Class II correction-reducing patient compliance: a review of the available techniques. J Orthod 2000;27:219-225. 36. Cope JB, Buschang, P.H., Cope, D.D., Parker, J., Blackwood 3rd, H.O. Quantitative evaluation of craniofacial changes with Jasper Jumper therapy. Angle Orthod 1994;64:113-122. 37. Weiland FJ, Bantleon HP. Treatment of Class II malocclusions with the Jasper Jumper appliance--a preliminary report. Am J Orthod Dentofacial Orthop 1995;108:341-350. 38. Stucki N, Ingervall B. The use of the Jasper Jumper for the correction of Class II malocclusion in the young permanent dentition. Eur J Orthod 1998;20:271-281. 39. Covell Jr DA, Trammell, D.W., Boero, R.P., West, R. . A cephalometric study of Class II, division1 malocclusions 49 treated with the Jasper Jumper appliance. Angle Orthod 1999;69:311-320. 40. DeVincenzo J. The Eureka Spring: a new interarch force delivery system. J Clin Orthod 1997;31:454-467. 41. Stromeyer EL, Caruso JM, DeVincenzo JP. A cephalometric study of the Class II correction effects of the Eureka Spring. Angle Orthod 2002;72:203-210. 42. 3M-Unitek. Forsus Fatigue Resistant Device with direct push rod; 2002. 43. Karacay S, Akin E, Olmez H, Gurton AU, Sagdic D. Forsus Nitinol Flat Spring and Jasper Jumper corrections of Class II division 1 malocclusions. Angle Orthod 2006;76:666-672. 44. Heinig N, Goz G. Clinical application and effects of the Forsus spring. A study of a new Herbst hybrid. J Orofac Orthop 2001;62:436-450. 50 Chapter III: Journal Article Abstract Introduction: The Forsus™ Fatigue Resistant Device (FRD) was tested as a compliance-free alternative to Class II elastics. Methods: A sample of 34 (14 females, 20 males) consecutively treated non-extraction FRD patients ages 9 years, 0 months to 17 years, 0 months were matched with a sample of 34 (14 females, 20 males) consecutively treated non-extraction Class II elastics patients ages 9 years, 0 months to 17 years, 0 months based on four pretreatment variables (ANB, L1-GoMe, SN-GoMe, and treatment duration). Pre- and post-treatment cephalometric radiographs were traced and analyzed using the pitchfork analysis and a vertical cephalometric analysis. T-tests were used to evaluate differences between groups. Results: No statistically significant differences were found in the treatment changes between the groups. There was a general trend for mesial movement of the maxilla, mandible, and dentition during treatment for both groups. The mandibular skeletal advancement and dental movements were greater than 51 those in the maxilla, which accounted for the Class II correction. groups. Lower incisor proclination was seen in both Vertically, both the maxillary and mandibular molars exhibited eruption during treatment in both groups, while lower incisor proclined with the incisal edge moving closer to the lower border of the mandible. Conclusions: The Forsus™ FRD is an acceptable substitute for Class II elastics for patients who appear to be non-compliant. Greater forward displacement of the mandible compared to the maxilla was the predominant factor in successfully treated Class II patients with both Class II elastics and the Forsus™ FRD appliance. Introduction Class II malocclusion presents a major and frequent challenge to orthodontists. According to NHANES III, Class II malocclusion (based on overjet measurements greater than 4 mm) is present in approximately 11% of the US population and comprises approximately one-fifth of all malocclusions.1 Data collected from 1966 to 1970 by the 52 United States National Health Survey, showed a similar prevalence of Class II relationship. Numerous orthodontic techniques and appliances aimed at producing a predictable resolution of Class II malocclusions have been introduced,including fixed or removable intra-arch appliances, fixed or removable inter-arch appliances, selective extraction patterns, and surgical repositioning of one or both jaws. Class II intermaxillary elastics are a typical interarch method used for correction. The effects of Class II elastics include mesial movement of the mandibular molars, mesial movement and tipping of the mandibular incisors, distal movement and tipping of the maxillary incisors, extrusion of the mandibular molars and maxillary incisors, and clockwise rotation of the mandibular plane and the occlusal plane.2-7 Intermaxillary elastics rely heavily on patient compliance for their effectiveness. Compliance in orthodontics is variable and difficult to predict.8 Poor cooperation can lead to poor treatment results and/or increased treatment time.9,10 Therefore, a number of compliance-free inter-arch appliances have been developed. Fixed inter-arch appliances typically demonstrate mesial movement of the mandibular molars and mesial movement at 53 tipping of the mandibular incisors. Reports on other effects vary, particularly those pertaining to mandibular growth.11-20 Only one study has compared the effects of Class II correction obtained with elastics to those obtained with fixed inter-arch (Herbst) appliances.4 It showed that anterior lower facial height and the mandibular plane angle increased more in the elastics group than in the Herbst group. While molar corrections were similar, the skeletal improvement was 10% in the elastics group, compared with 66% in the Herbst group. It is significant that little attention has been paid to the effects of Class II elastics compared to noncompliance appliances, because these appliances have the potential to be compliance-free alternatives in instances where the level of patient compliance required for successful treatment has not been reached. Although fixed inter-arch appliances may achieve a successful result en lieu of Class II elastics, the skeletal and dental changes that they produce may be significantly different from elastics. It is important that the potential differences be identified and understood, so that an appropriate decision can be made in evaluating appliances. The present study was designed to evaluate the effects of the Forsus™ Fatigue Resistant Device (FRD). 54 The Forsus™ FRD is a three-piece, telescoping system that incorporates a super-elastic nickel-titanium coil spring. The FRD can be assembled chair-side in a relatively short amount of time because the device consists of only three parts, it is completely compatible with complete fixed orthodontic appliances, and it can be fabricated and incorporated into the orthodontist’s pre-existing appliance. The FRD attaches at the maxillary first molar and on the mandibular archwire, distal to either the canine or first premolar bracket. As the coil is compressed, opposing forces are transmitted to the sites of attachment. The properties of the spring, theoretically, allow it to maintain a continuous force without the possibility of fatigue. Our purpose was to determine the skeletal and dental effects produced during Class II correction with the Forsus™ FRD compared to the effects of Class II elastics. Class II elastics were chosen as the comparison group because it represents a typical compliance-reliant method of Class II correction. Materials and Methods Sample A pre-treatment sample (T1) of 98 consecutively treated patients (41 Forsus™ FRD and 57 Class II elastics) 55 was selected from the offices of two private practice orthodontists (74 records from practice A and 24 records from practice B). • The criteria for patient selection were: Pre-treatment occlusion of at least end-on Class II malocclusion • Treatment completed without any permanent teeth extracted (excluding third molars) • Class I post-treatment occlusion • Starting age between of 9.0 years and 17.0 years • Good quality pre- and post-treatment cephalometric radiographs Patients were rejected if any appliances other than Forsus™ FRD or Class II elastics were used to correct the Class II malocclusion. Most previous reports of fixed inter-arch appliances measured changes at the removal of the appliances, rather than at the end of comprehensive treatment. The present study was designed to measure and describe the posttreatment differences between groups that were matched at the start of treatment, but used different appliances to correct the molar relationship. Except for the method of Class II correction employed, the treatments of the groups were similar, consisting of full, fixed orthodontic 56 appliances. By limiting the sample to two practitioners, variation in treatment technique was minimized. Class II elastics were initially prescribed in the treatment of the patients in the Forsus™ sample and may have been worn after Forsus™ removal in order to maintain the occlusal relationship. In this respect, the patients in Forsus™ sample should be considered Forsus™ FRD/Class II elastics patients. Regardless, the Forsus™ appliance was the appliance that was ultimately prescribed for Class II correction in this group. A dispersion analysis based on ANB, L1-GoMe, and SN-GoMe angles, as well as treatment duration was performed in order to ensure comparability across samples. Outlying subjects were removed to match the samples based on starting skeletal relationships. The final sample consisted of 34 subjects per group (Table 3.1). The post- treatment (T2) records were processed after the outlying subjects had been removed. Data Collection The pre- and post-treatment cephalometric radiographs were hand-traced on acetate paper and 15 landmarks were identified (Table 3.2). In order to describe the skeletal 57 and dental sagittal treatment changes that occurred, the radiographs were analyzed using the pitchfork analysis (PFA).21 The PFA accounts for and summarizes sagittal mandibular and maxillary molar movements, sagittal maxillary and mandibular advancement relative to the cranial base, and the contributions of all of these movements in correcting the molar relationship (Figure 3.1). Distal maxillary skeletal and dental movements and mesial mandibular skeletal and dental movements, which aid in Class II correction, were assigned positive values. Movements that worsen Class II relations were assigned negative values. Incisor movements that affect overjet were also measured and summarized. All measurements are made at the level of the occlusal plane. In this instance, the functional occlusal plane (FOP) was drawn through the occlusal contact points of the molars and premolars. Because the Forsus™ and Class II elastics were expected to produce vertical and angular changes of the dentition not described by the PFA, the following measurements were also included: 1. mandibular incisor (L1) angulation in relation to the mandibular plane (Go-Me) 2. maxillary incisor (U1) angulation to the SellaNasion line (SN) 58 3. maxillary molar (U6) mesial contact point vertical distance perpendicular to Anterior Nasal SpinePosterior Nasal Spine (ANS-PNS) 4. mandibular molar (L6) mesial contact point vertical distance perpendicular to Gonion-Menton (GoMe) 5. maxillary incisor (U1 incisal edge vertical distance perpendicular to ANS-PNS 6. mandibular incisor (L1) incisal edge vertical distance perpendicular to Gonion-Menton (Go-Me) 7. functional occlusal plane (FOP) to Sella-Nasion (SN) Statistical Methods Statistical analysis was preformed using SPSS version 14.0 (SPSS Incorporated, Chicago, IL). The skewness and kurtosis statistics indicated normal distributions. Independent t-tests were used to evaluate group differences. Mean and standard deviation were used to describe central tendencies and dispersion. To insure intra-examiner reliability, nine radiographs were randomly selected, re-traced, and angles and distances were re-measured. Cronbach’s Alpha test for reliability showed that intraclass correlation was 0.987. 59 Results Cephalometric Comparison Pre-Treatment No significant (p< .05) pre-treatment (T1) differences existed between the two treatment groups for the variables used for matching (ANB, L1-GoMe, SN-GoMe, and treatment duration, Table 3.3). The pre-treatment ANB was 0.7 degrees greater in the Forsus™ group. L1-GoMe, SN-GoMe, and treatment duration were closely matched. A statistically significant difference did exist between the groups at T1 for U1-SN. The elastics group had a higher U1-SN angulation than the Forsus™ group (103.1 degrees and 98.3 degrees, respectively). Post-Treatment Statistically significant (p< .05) differences were found post-treatment (T2) between the groups for L1-GoMe vertical distance and OP-SN angle (Table 3.5). The other differences between the groups were not statistically significant (p< .05). U1-ANS-PNS, U6-ANS-PNS, and L6-GoMe vertical distances were similar in both groups. 60 Treatment Changes Measured By Pitchfork The pitchfork analysis showed that the maxilla moved mesially 1.5 mm and the mandible moved mesially 3.8 mm in the elastics group; the average apical base change was 2.3 mm (Table 3.4, Figure 3.2). The maxillary molar moved mesially 0.6 mm and the mandibular molar moved mesially 0.7 mm. Total molar change (maxillary molar + mandibular molar + apical base change) was 2.4 mm. The upper incisor moved mesially 0.3 mm and the lower incisor moved mesially 0.8 mm. Total incisor change (upper incisor + lower incisor + apical base change) was 2.8 mm. All changes were statistically significant (p<.05), except for maxillary incisor movement. In the Forsus™ group, the pitchfork analysis showed that the maxilla moved mesially 1.7 mm and the mandible moved mesially 4.4 mm; the average apical base change was 2.6 mm. The maxillary molar moved mesially 1.2 mm and the mandibular molar moved mesially 1.8 mm. Total molar change (maxillary molar + mandibular molar + apical base change) was 3.2 mm. The upper incisor moved mesially 0.7 mm and the lower incisor moved mesially 1.2 mm. Total incisor change (upper incisor + lower incisor + apical base change) 61 was 3.2 mm. All changes were statistically significant (p<.05), except for maxillary incisor movement. The pitchfork analysis showed differences between the groups for lower molar movements and total molar corrections during treatment (Figure 3.2). The 1.1 mm more mesial movement and the 0.8 mm greater molar correction in the Forsus™ group were statistically significant (p< .05 and p< .01, respectively). During treatment, the mandible and maxilla moved mesially, with the mandible moving a greater amount than the maxilla in both groups. Upper molars and upper and lower incisors were moved mesially in similar amounts in both groups. Overjet was improved in both groups. Vertical and Angular Treatment Changes The vertical and angular treatment changes showed no statistically significant (p< .05) group differences. For both groups, the U1-SN and L1-GoMe angulations increased, the upper incisor tip moved further, vertically, from ANS-PNS and the lower incisor tip moved closer to GoMe. The upper and lower molars increased their vertical distances from ANS-PNS and GoMe, respectively. The occlusal plane rotated clockwise in both groups. 62 Discussion The molar relationships of patients treated with elastics were corrected primarily due to mandibular growth changes. Anterior mandibular displacement and mesial mandibular molar movements accounted for approximately 158% and 29% of the correction, respectively. Treatment changes in the maxilla worked against the molar correction, with anterior maxillary skeletal and dental movements limiting the correction by approximately 63% and 25%, respectively. Similar amounts of mandibular and maxillary advancements have been previously reported for Class II elastic treatments.22-24 Mesial movements of the maxilla, which works against Class II correction, is a common finding in elastics patients, even with the use of headgear.23,24 Non- extraction Class II patients treated with standard edgewise appliances, Class II elastics, and headgears show mandibular displacements and dental movements accounting for approximately 66% and 22% of the Class II correction, and distal maxillary molar movement contributed another 29%; anterior maxillary skeletal movements limits the correction by approximately 20%.23 The use of a prescription appliance without headgear could account for the maxillary molar anchorage loss seen in this study. 63 Molar anchorage is enhanced with headgear or Begg anchor bends, both of which produce distal crown movement of the maxillary molars.23,25 Anchorage loss in patients treated with prescription appliances is approximately 1 mm greater than with standard edgewise treatment.26 Because total molar correction was less than previously reported with the PFA, suggesting a less severe initial Class II relationship, greater maxillary molar anchorage loss could be tolerated while achieving satisfactory occlusal results.23,25 Nelson et al. showed similar amounts of molar correction in patients successfully treated with Class II elastics and the Begg appliance.24 The vertical relationships of the teeth and occlusal plane in the elastics patients indicate treatment modifications of normal growth. Maxillary and mandibular molars, as well as maxillary incisors, experienced eruption during treatment, as previously reported for elastics treatment.2,27,28 Untreated controls show similar amounts of maxillary molar eruption over a comparable time span, but less mandibular molar eruption.16 This suggests that Class II elastics may have contributed to additional mandibular molar eruption during treatment. The OP-SN decreased (rotated counterclockwise) 1.0 degrees, which was contrary to the clockwise rotation previously reported for elastics, 64 but the differences are relatively small.2 Counterclockwise rotation of the occlusal plane is normally observed in untreated patients during adolescence and may have counteracted the clockwise rotational tendency that mandibular molar and maxillary incisor eruption would be expected to affect.16 Differences could also be attributed to the use of the functional occlusal plane was in this study, rather than the Down’s occlusal plane or Pancherz’s occlusal line, which are commonly used.2,14,15,18,20 The functional occlusal plane, which is drawn through the occlusal contact points of the first molars and premolars, is less likely to rotate clockwise as upper incisors extrude and lower incisors procline than planes which use the incisors for reference. As in the elastics group, molar correction for the patients treated with the Forsus™ FRD appliance was predominately due to mesial mandibular skeletal and dental movements. Anterior mandibular displacement and mesial mandibular molar movement accounted for approximately 138% and 56% of Class II correction, respectively. Treatment changes with the Forsus™ also worked against molar correction, as mesial skeletal and molar movements limited correction by 91%. DeVincenzo,13 who quantified the skeletal and dental contributions to Class II correction 65 with the Eureka Spring, showed distal movement of the maxilla (contributing 11%) and maxillary molars (contributin 33%); mesial mandibular molar movements contributing an additional 60%, and; relative posterior movement of the mandible limiting molar correction by 4%. However, DeVincenzo used the pterygoid vertical reference line to calculate dental and skeletal changes. The functional occlusal plane, which was used as a reference in this study, tends to show relatively greater skeletal contributions in Class II correction.29 Karacay et al.30 reported no maxillary movement, approximately 1 mm of anterior mandibular displacement, and equal amounts of distal maxillary molar and mesial mandibular molar movements in patients treated with the Forsus™ Nitinol Flat Spring (NFS). Other authors have also reported distal movement of maxillary molars with the Forsus™ NFS and similar appliances.11,16,20,30,31 The studies showing the greatest distal effect on the maxillary molars measured the effects immediately after inter-arch appliance removal.11,18,20 Mesial movement with growth and anchorage loss due to additional orthodontic treatment may mask or negate these distal movements. Stucki and Ingerval18 showed that mesial maxillary molar movement occurred during the observation period following removal of the Jasper Jumper. 66 Evaluation of patients treated with the Forsus™ FRD appliance in this study was made after completion of orthodontic treatment. After Class I molar occlusion is achieved and appliances are removed, it would be expected that the maxillary molars would move mesially to keep pace with the mandibular molars. Fewer significant vertical changes were seen in the Forsus™ group than the elastics group. The maxillary and mandibular molars both experienced eruption, but no significant changes were seen for the upper incisors or occlusal plane. Similar amounts of mandibular molar extrusion have been reported in Forsus™ NFS patients and Jasper Jumper patients.11,12,18,30 Forsus™ NFS, Jasper Jumper, and Eureka Spring reports show intrusion of the maxillary molars.11-13,18,30 However, these reports again measured molar position immediately after appliance removal, rather than after treatment was finished. Stuki and Ingerval18 showed that, after Jasper Jumpers were removed, eruption of the maxillary molars followed the intrusion that occurred during treatment. The present study measured changes after orthodontic treatment was completed, and if intrusion was achieved with Forsus™ treatment, it is followed by eruption, which occurs with normal growth. 67 Comparison of the overall effects in the Forsus™ and elastics groups reveals a relatively greater mesial movement of the dentition, the maxilla, and the mandible in the Forsus™ group. Since a Class I molar relationship was the final result in both groups, the Forsus™ group may have started with a greater molar discrepancy. The change in L1-GoMe angulation was 2.5 degrees greater in the Forsus™ group than in the elastics group, but this difference was also not statistically significant. As the lower incisor tip proclines, the vertical distance from incisal tip to mandibular border would be expected to decrease in proportion to its proclination. Both groups studied experienced decreases in the vertical distance from the incisal tip of the lower incisors to the mandibular plane during treatment. The lower incisor proclined more and the vertical distance from incisal tip to mandibular border (L1-GoMe) decreased more in the Forsus™ group. While group differences were evident for extrusion of maxillary dentition as well as maxillary and mandibular incisor proclination, the differences were not statistically significant. This was due to the amount of variation in treatment changes seen within the groups. Large variation in treatment changes is a common finding in treated Class II patients.2,11-13,16,19,30 68 The variation is likely due to the movements required to correct the different types of dental compensations typically seen in Class II patients. Greater severity of the malocclusion will require more extreme dental compensations. Although care was taken to keep both groups closely matched at the start of treatment, there were some differences between the groups at T1. The maxillary incisor angulations were statistically different at the start of treatment, with the Forsus™ group being more upright (98.9 degrees compared to 103.1 degrees in the elastics group). At the end of treatment there were no differences in upper incisor angulations between the groups. Cephalometric analysis showed that U1-SN proclination was greater in the Forsus™ group, which is in agreement with the pitchfork analysis showing a greater tendency for mesial movement of the incisors in the Forsus™ group. Conclusions 1) The Forsus™ FRD is an acceptable substitute for Class II elastics for patients who appear to be noncompliant. 69 2) Greater forward displacement of the mandible compared to the maxilla was the predominant factor in successfully treated Class II patients with both Class II elastics and the Forsus™ FRD appliance. Acknowledgements The authors wish to acknowledge Dr. Kevin Walde and Dr. William Vogt for generously providing the records for this study and Dr. Heidi Israel and Dr. Lysle E. Johnston, Jr for their assistance during this project. References 1. Proffit WR, Fields HW, Jr., Moray LJ. Prevalence of malocclusion and orthodontic treatment need in the United States: estimates from the NHANES III survey. Int J Adult Orthodon Orthognath Surg 1998;13:97-106. 2. Ellen EK, Schneider BJ, Sellke T. A comparative study of anchorage in bioprogressive versus standard edgewise treatment in Class II correction with intermaxillary elastic force. Am J Orthod Dentofacial Orthop 1998;114:430436. 3. Gianelly AA, Arena SA, Bernstein L. A comparison of Class II treatment changes noted with the light wire, 70 edgewise, and Frankel appliances. Am J Orthod 1984;86:269276. 4. Nelson B, Hansen K, Hagg U. Class II correction in patients treated with class II elastics and with fixed functional appliances: a comparative study. Am J Orthod Dentofacial Orthop 2000;118:142-149. 5. Remmer KR, Mamandras AH, Hunter WS, Way DC. Cephalometric changes associated with treatment using the activator, the Frankel appliance, and the fixed appliance. Am J Orthod 1985;88:363-372. 6. Adams CD, Meikle MC, Norwick KW, Turpin DL. Dentofacial remodelling produced by intermaxillary forces in Macaca mulatta. Arch Oral Biol 1972;17:1519-1535. 7. Hanes RA. Bony profile changes resulting from cervical traction compared with those resulting from intermaxillary elastics. Am J Orthod 1959;45:353-364. 8. Brandao M, Pinho HS, Urias D. Clinical and quantitative assessment of headgear compliance: a pilot study. Am J Orthod Dentofacial Orthop 2006;129:239-244. 9. Beckwith FR, Ackerman RJ, Jr., Cobb CM, Tira DE. An evaluation of factors affecting duration of orthodontic treatment. Am J Orthod Dentofacial Orthop 1999;115:439-447. 10. Skidmore KJ, Brook KJ, Thomson WM, Harding WJ. Factors influencing treatment time in orthodontic patients. Am J Orthod Dentofacial Orthop 2006;129:230-238. 11. Cope JB, Buschang, P.H., Cope, D.D., Parker, J., Blackwood 3rd, H.O. Quantitative evaluation of craniofacial changes with Jasper Jumper therapy. Angle Orthod 1994;64:113-122. 12. Covell Jr DA, Trammell, D.W., Boero, R.P., West, R. . A cephalometric study of Class II, division1 malocclusions 71 treated with the Jasper Jumper appliance. Angle Orthod 1999;69:311-320. 13. DeVincenzo J. The Eureka Spring: a new interarch force delivery system. J Clin Orthod 1997;31:454-467. 14. Pancherz H. Treatment of class II malocclusions by jumping the bite with the Herbst appliance. A cephalometric investigation. Am J Orthod 1979;76:423-442. 15. Pancherz H. The effects, limitations, and long-term dentofacial adaptations to treatment with the Herbst appliance. Semin Orthod 1997;3:232-243. 16. Pangrazio-Kulbersh V, Berger JL, Chermak R, Simon ES, Haerian A. Treatment effects of anterior repositioning appliance on patients malocclusion. Am J Orthod Dentofacial Orthop 295. DS, Kaczynski the mandibular with Class II 2003;123:286- 17. Stromeyer EL, Caruso JM, DeVincenzo JP. A cephalometric study of the Class II correction effects of the Eureka Spring. Angle Orthod 2002;72:203-210. 18. Stucki N, Ingervall B. The use of the Jasper Jumper for the correction of Class II malocclusion in the young permanent dentition. Eur J Orthod 1998;20:271-281. 19. Valant JR, Sinclair PM. Treatment effects of the Herbst appliance. Am J Orthod Dentofacial Orthop 1989;95:138-147. 20. Weiland FJ, Bantleon HP. Treatment of Class II malocclusions with the Jasper Jumper appliance--a preliminary report. Am J Orthod Dentofacial Orthop 1995;108:341-350. 21. Johnston LE, Jr. Balancing the books on orthodontic treatment: an integrated analysis of change. Br J Orthod 1996;23:93-102. 72 22. Egolf RJ, BeGole EA, Upshaw HS. Factors associated with orthodontic patient compliance with intraoral elastic and headgear wear. Am J Orthod Dentofacial Orthop 1990;97:336348. 23. Johnston LE, Jr. A comparative analysis of Class II treatments. Ann Arbor, Center for Human Growth; 1986. 24. Nelson B, Hansen K, Hagg U. Overjet reduction and molar correction in fixed appliance treatment of class II, division 1, malocclusions: sagittal and vertical components. Am J Orthod Dentofacial Orthop 1999;115:13-23. 25. Reddy P, Kharbanda OP, Duggal R, Parkash H. Skeletal and dental changes with nonextraction Begg mechanotherapy in patients with Class II Division 1 malocclusion. Am J Orthod Dentofacial Orthop 2000;118:641-648. 26. Johnston. Personal communication. In: Jones G, editor. St Louis; 2006. 27. Bien SM. Analysis of the components of force used to effect distal movement of teeth. Am J Orthod 1951;37:508521. 28. Zingeser M. Vertical response to Class II division 1 therapy. Angle Orthod 1964;34:58-64. 29. Mannchen R. A critical evaluation of the pitchfork analysis. Eur J Orthod 2001;23:1-14. 30. Karacay S, Akin E, Olmez H, Gurton AU, Sagdic D. Forsus Nitinol Flat Spring and Jasper Jumper corrections of Class II division 1 malocclusions. Angle Orthod 2006;76:666-672. 31. Heinig N, Goz G. Clinical application and effects of the Forsus spring. A study of a new Herbst hybrid. J Orofac Orthop 2001;62:436-450. 73 Figures 74 Distal Mesial Max + Mand = ABCH ABCH + U6 + L6 = 6/6 ABCH + U1+ L1 = 1/1 Figure 3.1: Diagram of pitchfork analysis (modified from Johnston) Maxilla, mandible, molar, and incisor changes are all represented. Mesial movements of the mandible and mandibular dentition or distal movements of the maxilla and maxillary dentition aid in Class I and overjet correction and are assigned positive values. Mesial movements of the maxilla and maxillary dentition or distal movements of the mandible and mandibular dentition make Class II malocclusion and overjet more severe and are assigned negative values. The amount of mesial or distal movement of the mandible in relation to the maxilla is summarized as apical base change (ABCH). Correction of molar relationship and overjet are summarized based on skeletal (ABCH) and dental contributions. B A 75 C Figure 3.2: Pitchfork summaries of treatment changes Positive signs indicate movements in a direction which aids Class I correction (distal movements in the maxilla/mesial movements in the mandible). Negative signs indicate movements which make Class II occlusion more severe (mesial movements in the maxilla/distal movements in the maxilla). A) Treatment changes in elastics group B) Treatment changes in Forsus™ group C) Summary of differences between groups (Forsus™ - elastics) 76 Table 3.1 Sample Description Males Females Class II elastics Forsus™ 20 14 Average Start Age 12.2 20 14 12.6 Tables 77 Group Table 3.2: Summary of Cephalometric Landmarks and Definitions LANDMARK Abbrev DEFINITION A point A The deepest point on the premaxilla below ANS The tip of the anterior nasal spine Anterior Nasal Spine SE point ANS SE B Point B D point D Upper 6 U6 The mesial contact point of the maxillary first molar Lower 6 L6 The mesial contact point of the mandibular first molar Lower Incisor L1 The tip of the incisal edge of the mandibular central incisor Upper Incisor U1 The tip of the incisal edge of the maxillary central incisor Posterior Nasal Spine Sella PNS The most posterior point on the bony hard palate S The center of the pituitary fossa Nasion N The most anterior point of the frontonasal suture Gonion Go Menton Me Functional Occlusal Plane FOP The most anterior and inferior point at the angle of the mandible The most inferior point of the mandibular symphysis Plane drawn through the occlusal contact points of the molars and premolars The intersection of the averaged greater wings and planum of the sphenoid The deepest part of the anterior mandible The center of the cross-section of the mandibular symphysis 78 Table 3.3: Pre-treatment comparison of elastics and Forsus™ groups for matched variables. Elastics Sample Forsus™ Sample Value Units x SD x SD Sig 79 ANB deg 4.6 1.7 5.3 1.5 .10 L1-GoMe deg 95.7 6.3 93.8 7.2 .25 SN-GoMe deg 32.4 5.1 33.1 5.2 .52 Treatment Duration years 2.4 0.9 2.7 0.9 .12 Table 3.4: Pitchfork analysis comparison of treatment changes in elastics and Forsus™ groups. Positive signs indicate movements in a direction which aids Class II correction (distal movements in the maxilla/mesial movements in the mandible), negative signs indicate movements which make Class II occlusion more severe (mesial movements in the maxilla/distal movements in the maxilla). _ Elastics Group_ __Forsus™ Group_ 80 Variable Units mean SD mean SD Max mm -1.5** 1.3 -1.7** 1.1 .47 Mand mm 3.8** 2.5 4.4** 2.2 .33 ABCH mm 2.3** 1.7 2.6** 1.8 .44 U6 mm -0.6** 1.1 -1.2** 1.5 .06 L6 mm 0.7** 1.3 1.8** 1.5 < .00 U6/L6 mm 2.4** 1.2 3.2** 1.7 .03 U1 mm 2.0 .50 L1 mm -0.3 2.6 -0.7 Sig 2.0 1.2** 2.2 .42 0.8* U1/L1 mm 2.8** 2.2 3.2** 1.9 .47 Bold values indicate statistical significance between groups (p < .05) * denotes changes are significant at p< .05 ** denotes changes are significant at p< .01 Table 3.5: Comparison of pre and post-treatment variables and treatment changes in elastics and Forsus™ groups. ____Pre-Treatment _ Elastics Forsus™ Var units mean SD ___Post-Treatment__ _ Elastics Forsus™ mean SD Sig mean SD 103.1 7.9 98.3 8.5 .01 103.7 5.8 mean SD Treatment Changes _ Elastics Forsus™ Sig mean SD mean SD Sig 81 7.3 .28 0.6 9.3 3.7* 8.9 .16 3.5 .80 1.2** 2.1 0.5 2.3 .24 2.5 .41 2.0** 2.0 1.5** 1.7 .20 .48 99.7 5.9 100.9 8.2 .49 3.8** 5.5 6.3** 7.0 .11 7.4 .41 77.4 6.0 74.0 7.9 .04 -3.7** 5.4 -5.9** 6.4 .14 25.2 2.8 .16 29.3 2.6 28.5 3.1 .28 1.9 2.0 .86 19.2 4.1 .16 16.9 4.0 19.0 4.1 .03 -1.0 3.3 .34 U1-SN deg U1ANSPNS mm 25.9 2.8 26.6 2.8 .21 27.0 3.1 U6ANSPNS mm 18.3 2.2 18.4 2.3 .87 20.3 2.4 L1-GoMe deg 95.8 6.2 94.6 8.0 L1-GoMe mm 81.1 6.3 79.8 L6-GoMe mm 26.1 2.0 OP-SN deg 17.9 3.8 102.0 27.2 19.9 3.2** 3.3** 3.2 -0.2 Bold values indicate statistical significance between groups (p < .05) * denotes changes are significant at p< .05 ** denotes changes are significant at p< .01 Vita Auctoris Graham Christopher Jones was born on November 6, 1977 in Los Angeles, California. In 1987 he and his family moved to Costa Rica, where they served as missionaries for one year. In 1991 he and his family moved to Des Moines, WA and he attended Seattle Christian School. He attended Highline College in MidWay, WA from 1995-1996, Simpson College in Redding, CA from 1996-1999, Shasta College in Redding, CA from 1997-1999, and San Francisco State University in San Francisco, CA from 1999-2000. He received his B.A. degree in Liberal Studies from Simpson College in 1999. Graham was a member of the men’s baseball and basketball teams at Simpson College and has spent time in Guatemala and the Philippines as part of an evangelical basketball team. In January 2000 he married Erika June Dilley in Palmer, AK. He entered dental school at the University of California at San Francisco (UCSF) in 2000. In 2004 he received his D.D.S. from UCSF. Following graduation from dental school, he began his studies at Saint Louis University, in pursuit of a Master’s Degree from the Orthodontics program. Upon graduation in January 2007, he, his wife, Erika, and their son, Justus, will relocate to the state of Washington where he will begin his career as an orthodontist. 82