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EVALUATION OF FINAL EFFECTS OF CONVENTIONAL VERSUS IMPLANT SUPPORTED DISTAL JET FOLLOWED BY COMPREHENSIVE ORTHODONTIC TREATMENT! ! ! ! ! Krystal M. Baumgartner, D.D.S.! ! ! ! An Abstract Presented to the Graduate Faculty of Saint Louis University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Dentistry 2012 Abstract Purpose: The objective of this study is to evaluate and compare the final treatment dental and skeletal effects of the conventional Distal Jet and the miniscrew implant (MI) supported Horseshoe Distal Jet appliance. Materials and Methods: Lateral cephalometric radiographs were obtained on 54 subjects to perform this retrospective study. The subjects were divided into two groups based on the type of Distal Jet used. Group 1 consisted of 27 subjects treated with a tooth-supported Distal Jet and Group 2 was comprised of 27 subjects treated with a miniscrew implant (MI) supported Horseshoe Jet. Following the Distal Jet appliance, all patients underwent full comprehensive orthodontic treatment. Pre- and post- treatment radiographs were hand-traced and measurements were analyzed with the pitchfork analysis. Angular changes in the upper first molar and upper incisor were evaluated by measuring the long axes of the teeth relative to the mean functional occlusal plane. Information about treatment time was used to determine if there is a difference in the amount of time required to treat the patients. Independent t-tests were used to compare 1 skeletal/dental effects and treatment time between the groups. Results: Both groups showed a forward movement of the maxilla and mandible. At the end of comprehensive orthodontic treatment, the upper molar in both groups had experienced distal movement. The difference in lower molar change was significant with the tooth-supported group having a greater contribution to molar correction with more mesial movement. The change in upper incisor movement and angulations among the two groups was not significant. Group 2 had a distal movement of the lower incisors that was a significant difference from the mesial movement seen in Group 1. Treatment time in Group 1 was 1.6 months longer compared to Group 2. Conclusions: (1) In comparing Class II treatment with the tooth-supported versus the miniscrew implant supported Distal Jet followed by fixed orthodontic appliances, no advantage of one appliance over the other was demonstrated. (2) The final effects of Class II molar correction and overjet in the groups showed no significant difference. (3)Difference in total treatment time with the two types of Distal Jet is not significant. 2 EVALUATION OF FINAL EFFECTS OF CONVENTIONAL VERSUS IMPLANT SUPPORTED DISTAL JET FOLLOWED BY COMPREHENSIVE ORTHODONTIC TREATMENT ! ! ! ! Krystal M. Baumgartner, D.D.S.! ! ! ! A Thesis Presented to the Graduate Faculty of Saint Louis University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Dentistry 2012 ! COMMITTEE IN CHARGE OF CANDIDACY: Professor Eustaquio A. Araujo Chairperson and Advisor Professor Rolf G. Behrents Associate Clinical Professor Donald R. Oliver i! ! ! ACKNOWLEDGEMENTS I would like to express my gratitude and appreciation to the following individuals: Dr. Araujo, for his continual support, patience, and encouragement not only as my committee advisor but throughout my residency. His vast knowledge, clinical skills, and passion about orthodontics have been invaluable to my education and experience. The things I have learned from him will stay with me throughout my life and career. I am sincerely grateful for all his kind words and confidence he gave me. Dr. Behrents, for allowing me to be a part of the orthodontic program at Saint Louis University, and for his assistance on my thesis. I appreciate the chance to be a resident at an institution that provides a remarkable clinical and didactic experience. His orthodontic knowledge and dedication to the residents have played a large role in guiding me throughout my residency. Dr. Oliver, for his commitment and care in all the phases of my orthodontic education. His dedication and encouragement in the classroom carried to my clinical experience. His knowledge and skill allowed me to develop ii ! as a clinician and will continue to influence me in my orthodontic career. Dr. Bowman, for providing the records that were used in this study. He was very informative and always available to answer all of my questions in assisting me with gathering information. I appreciate his generosity in giving me his time and sharing his knowledge with me. A special thank you to Heidi Israel in assisting me with the statistical analysis. Despite her demanding schedule, she was willing to take time in helping me gain data and providing explanations to me whenever needed. iii ! TABLE OF CONTENTS List of Tables……………………………………………………………………………………………………………………v List of Figures………………………………………………………………………………………………………………vi CHAPTER 1: INTRODUCTION……………………………………………………………………………………………1 CHAPTER 2: REVIEW OF THE LITERATURE The Class II Malocclusion………………………………………………………………………………………4 Prevalence of Class II Malocclusion………………………………………………5 Etiology of Class II Malocclusion……………………………………………………6 Class II Correction…………………………………………………………………………………………7 The Role of Compliance in Treatment…………………………………………………………11 Maxillary Distalizers Requiring Minimal Compliance…………………12 NiTi Coil Springs……………………………………………………………………………………………13 Jones Jig…………………………………………………………………………………………………………………13 Pendulum……………………………………………………………………………………………………………………15 Distal Jet………………………………………………………………………………………………………………16 Miniscrew Implants as Anchorage……………………………………………………………………19 Implant Supported Distalizers…………………………………………………………………………20 Distal Jet……………………………………………………………………………………………………………………………22 Tooth-Supported Distal Jet……………………………………………………………………22 Miniscrew Implant Supported Horseshoe Distal Jet…………25 Measuring Class II Correction…………………………………………………………………………28 Statement of Thesis……………………………………………………………………………………………………30 References……………………………………………………………………………………………………………………………31 CHAPTER 3: JOURNAL ARTICLE Abstract…………………………………………………………………………………………………………………………………37 Introduction………………………………………………………………………………………………………………………40 Materials and Methods………………………………………………………………………………………………42 Sample…………………………………………………………………………………………………………………………42 Data Collection…………………………………………………………………………………………………44 Statistical Methods………………………………………………………………………………………47 Results……………………………………………………………………………………………………………………………………48 Discussion……………………………………………………………………………………………………………………………52 Skeletal Changes………………………………………………………………………………………………53 Dental Changes……………………………………………………………………………………………………54 Conclusions…………………………………………………………………………………………………………………………57 Appendix…………………………………………………………………………………………………………………………………59 References……………………………………………………………………………………………………………………………60 Vita Auctoris…………………………………………………………………………………………………………………… iv ! LIST OF TABLES Table 2.1: Tooth-Supported Distalizers………………………………………14 Table 2.2: Implant-Supported Distalizers…………………………………22 Table 3.1: Characteristics of sex and age-matched samples……………………………………………………………………………………………43 Table 3.2: Samples defined at pre-treatment…………………………47 Table 3.3: Comparisons of sex and age-matched individuals with tooth-supported and MI supported Distal Jet appliances……………………………51 Table A.1: Description of pitchfork analysis cephalometric variables…………………………………………………61 v ! LIST OF FIGURES Figure 2.1: Original Distal Jet……………………………………………………………17 Figure 2.2: Bowman Modification Distal Jet………………………………23 Figure 2.3: Miniscrew implant supported Distal Jet…………27 Figure 3.1: Pitchfork analysis diagram…………………………………………46 Figure 3.2: Pitchfork summary of treatment changes…………50 vi CHAPTER 1: INTRODUCTION Class II malocclusions are frequent in the general population and they present a constant challenge to orthodontists in searching for ideal and efficient treatment methods. There are many treatment approaches and appliances available that are capable of correcting the Class II molar relation whether it is a result of dental or skeletal aberrations. The orthodontist’s decision about which appliance to use often depends on the skeletal or dental discrepancy as well as the treatment objectives and patient compliance. Many removable and fixed appliances are used for treating Class II malocclusions. In choosing the most efficient appliance for a specific problem one needs to consider the objectives of treatment, the developmental stage of the patient, the side effects of the appliance prescribed, as well as patient compliance. The need for compliance from the patient is a significant component of many Class II treatment approaches. Poor cooperation leads to longer treatment times and less than ideal outcomes. For this reason, clinicians have tried to develop methods that do not rely on patient compliance. 1! ! ! When the Class II malocclusion is a result of the maxillary first molars being positioned too far mesially in the dental arch, a mode of correction can be either to hold the molars in an effort to restrict their forward movement, to restrict forward growth of the maxilla, or to move the molars distally. This has been done traditionally with headgears and/or elastics as well as functional appliances. In an effort to avoid the needed cooperation required for successful headgear use a number of “distalizing” appliances have been developed (e.g.’s NiTi coil springs, Jones Jig, Pendulum, and the Distal Jet). A drawback of Class II distalizers, however, has been unwanted side-effects. Specifically the anterior anchorage loss and tipping of the incisors that result from distalizing the maxillary molars; necessitating time to correct after the distalization is complete. It also usually requires compliance in terms of wearing elastics. Miniscrew implants (MI) placed in the maxilla have been used in order to eliminate or lessen these such sideeffects. Instead of the reactive forces acting on the anterior maxillary dentition, the forces are distributed to the miniscrew implants and, in turn, to the supporting bone. 2 ! The Class II malocclusion is a common and important problem in orthodontics. Various approaches have been used over more than 100 years to attempt correction. In the last 40 years, distalizing appliances have been introduced to cause distal movement of the maxillary molars. More recently, miniscrew implants have been added as anchorage for more efficiency and effectiveness. In regards to distalizing appliances, skeletal anchorage is expected to decrease the amount of anchorage loss during maxillary molar distalization and subsequent retraction of the anterior teeth. This study will compare the final effects of a toothsupported Distal Jet and a miniscrew supported Distal Jet followed by fixed orthodontic appliances in correcting a Class II malocclusion. The skeletal and dental changes will be evaluated, and it will further investigate the difference in treatment time. 3 ! CHAPTER 2: REVIEW OF THE LITERATURE Class II Malocclusion Important goals that orthodontists aim to accomplish in their treatment include aesthetics, balance, function, and stability. A normal dental occlusion has been described for the human dentition and such serves as a goal of orthodontic treatment. In the 1890s, Angle’s classification of malocclusion not only subdivided the major types of malocclusion but also included the first clear and simple definition of normal occlusion in the natural dentition. Angle stated that the upper first molars were the key to occlusion. A Class I molar relationship was defined as having the upper and lower first molars related so that the mesiobuccal cusp of the upper molar occludes in the buccal groove of the lower molar.1 Furthermore, a Class II relationship was described as the lower molar distally positioned relative to the upper molar to the extent of more than one-half the width of one cusp. Angle’s classification addresses the dental component of the Class II malocclusion, however, the malocclusion may also have a craniofacial component. 4 ! Prevalence of Class II Malocclusion The third National Health and Nutrition Examination Survey (NHANES III) collected data on children in the United States and reported the prevalence of malocclusion and orthodontic treatment need. It was carried out from 1988 to 1994 and studied 14,000 individuals in order to make estimates for approximately 150 million persons based on the sampled racial/ethnic and age groups. The NHANES study, for their examination purposes and ease of application, redefined the Class II malocclusion as the presence of 5 mm or more overjet. By this definition that study found the incidence of “Class II” as 23% of children, 15% of youths, and 13% of adults.1,2 With increasing age and mandibular growth, the amount of overjet usually decreases. Therefore, the prevalence of the Class II malocclusion, by this definition, also decreases. A study done by Thilander et al3 on Colombian children and adolescents found that the prevalence increases with age until the late mixed dentition where it occurred in 24.9% of the sample, and then decreases to 18.5% in the permanent dentition. The prevalence of Class II problems in different racial groups has been reported in the literature and 5 ! varies in these studies from 12 – 40% of the population sampled.4 It is evident that there is much variation and there are certain groups of the population that have a greater tendency for certain malocclusions. With regards to male versus female prevalence, sex generally has little effect on dental and skeletal positions.5 As is seen, the Class II problem is present in a large percentage of the population and is therefore commonly seen by orthodontists. Etiology of Class II Malocclusions A Class II molar relationship, upon which Angle developed his classification, can be the result of many skeletal and dental combinations. Most of the studies conducted to investigate the cause and source of the Class II malocclusion have compared Class II individuals to normal Class I individuals or existing cephalometric standards. In 1981, McNamara6 performed a cross-sectional lateral cephalometric evaluation of the distribution of specific relationships in 277 subjects eight to ten years of age with a Class II malocclusion. The four major components that can contribute to the anteroposterior differences in a Class II individual that were measured and analyzed in this study were maxillary skeletal position, maxillary dentoalveolar position, mandibular dentoalveolar 6 ! position, and mandibular skeletal position. It is a variation in one of these, or a combination, that may result in a Class II malocclusion.6 The findings led to the conclusion that a Class II malocclusion is not a single clinical entity, but rather a result of numerous combinations of skeletal and dental components. McNamara stated that the most commonly occurring factor in Class II’s is the retrusion of the mandible and not the protrusion of the maxilla.6 For many patients, however, maxillary molar distalization is the chosen strategy for correction of the Class II malocclusion. These situations in which treating the maxillary arch is indicated for a Class II patient, distalizing the molars can gain space and correct posterior tooth malpositions.7 Class II Correction As described, there are a variety of dental and skeletal components that contribute to the problem and therefore to the decision-making process when planning treatment for a patient having a Class II malocclusion. Among the factors to consider are the profile, facial, skeletal and dental relationships in order to achieve the goals of treatment. 7 ! As mentioned previously, the prevalence of the Class II malocclusion decreases with increasing age. When Proffit1 describes the variability in the pattern of growth he states that it is a reflection of a “cephalocaudal gradient of growth.” This refers to the fact that there is more growth of the lower limbs than the upper limbs during postnatal life. This applies to the mandible which is farther away from the brain than the maxilla and therefore grows more and later in development. Proffit states that growth can usually only correct 3-4 mm of the Class II malocclusion. Unfortunately the advantage of the differential growth of the mandible does not affect every individual in the same manner. The chin in Class II, division 1 individuals is located relatively more posteriorly than in normal occlusion with a steeper mandibular plane angle.8 As a result of this growth pattern in which the mandible grows in a downward instead of forward direction, later growth may not aid in the sagittal discrepancy correction. Many orthodontists use functional appliances to attempt to take advantage of growth in an adolescent. The intent of the treatment would be to hold the mandible in a forward position during the growth period while restraining 8 ! the maxilla in order to achieve a better profile and aid in dental correction. These appliances have been shown to be efficient in correcting the molar relationship and the sagittal maxillomandibular skeletal differences in Class II subjects.9 Extraoral traction, or headgear, was reintroduced in the late 1940s and became a popular and effective method of Class II correction.1 It was used to cause distal movement of the maxillary molars in order to guide them in a Class I position. Headgear was thought by some to only cause dental movement until studies proved otherwise. In 1963, Wieslander and co-workers10 collected cephalometric records on 30 subjects in the mixed dentition with a Class II malocclusion that were treated with Kloehn-type cervical pull headgear. They were then compared to normal Class I children of the same age, sex and treatment time period. The use of cervical pull headgear in the mixed dentition period was shown to not only affect the maxilla, but also the surrounding bony structures in direct contact with the maxilla. In addition to retracting the maxillary molars, headgear was shown to have an orthopedic effect. This appearance may cause a posterior change in the position of the pterygomaxillary fissure, a smaller amount of forward 9 ! movement of the anterior nasal spine, and a tipping of the anterior part of the palatal plane in a downward direction.10 Many times in orthodontic treatment, extraction of teeth are done to achieve ideal treatment results. The patient’s skeletal relationship, dental malocclusion, and facial profile help guide the orthodontist into making an extraction decision. When extractions are indicated in order to aid in Class II correction the spaces created by extracting teeth are used to alleviate crowding and compensate for the Class II relation.1 Severe disharmonies of mandibular retrusion or maxillary protrusion have been treated with surgical procedures with success. Surgery may have to be performed in order to accomplish an ideal result if the skeletal discrepancy is severe enough where dentoalveolar treatment and/or camouflage will not meet treatment goals. All of the mentioned treatment options have been successful in treating Class II malocclusions and have their own strengths and shortcomings. Consequently, careful treatment planning is a must when deciding which modality to employ. 10 ! The Role of Compliance in Treatment When patient compliance is a factor in orthodontic treatment, predictability of the outcome and treatment time may become difficult. Treatment involving headgear, inter- maxillary elastics, or other removable appliances can only be effective if the patient meets the requirements of wearing such appliances and for the appropriate time. Studies have investigated treatment cooperation. Common findings among them have been that younger patients (≤12 years old) are more cooperative, and boys commonly have longer treatment times.11,12,13,14 Skidmore et al investigated factors influencing treatment time in orthodontic patients. They found that patients with at least one entry in their records of poor elastic wear increased treatment duration by a mean of 1.4 months.13 Treatment of Class II malocclusion often involves distalizing maxillary molars which is especially dependent on patient compliance. For this reason, the orthodontist may have to find an alternative treatment when there is a lack of progress in treatment due to the patient’s noncompliance with wearing an appliance. The development of non-compliance approaches attempts to remove some of the patient-determined variable factors that may affect 11 ! treatment time and the quality of the result.15 Unfortunately, they do not come free of drawbacks that may include appliance breakage and relatively high costs for appliance construction.15 Maxillary Distalizers Requiring Minimal Compliance Careful treatment planning is crucial, and the position of the anterior teeth in relation to the soft tissue profile must be assessed. In patients with a Class II malocclusion and maxillary dental protrusion, moving the upper molars posteriorly followed by anterior retraction is a frequently used option.1 After deciding that maxillary molar distalization is the treatment of choice, the next decision is to choose the appliance to accomplish this goal. Because cooperation has been an increasing problem, intraoral distalizing appliances that do not rely on the patient have become popular. Intraoral, dental-borne distalizers generally consist of an anchorage unit such as the premolars or deciduous molars, an acrylic Nance button, and an active unit.16 The Nance button is anchored against the palatal mucosa of the palate which, in theory, resists displacement. However, in clinical use anterior anchorage is lost and soft tissue irritation often results.1 12 It is ! challenging to move maxillary molars bodily distal, and additionally challenging to maintain their position when retracting the anterior teeth. There is an assortment of tooth-borne appliances that achieve distalization, however there is slight variation in the mode of anchorage, molar movement tactics, and the effects of each appliance (Table 2.1). NiTi Coil Springs Intra-arch NiTi coil springs combined with an anchorage unit have been used as a non-compliance method to Gianelly et al17 used super- distalize maxillary molars. elastic intra-arch NiTi coil springs distal to upper first premolars that were cemented to a modified Nance appliance to achieve this movement. Additional anchorage was achieved by the use of uprighting springs applied to the first premolars. Gianelly reported an average of 1-1.5 mm of molar distalization in one month with 8-10 mm activation of the 100 g NiTi springs.17 Jones Jig The Jones Jig18 is comprised of an active component and an anchorage unit. The active arm, or so-called Jig assembly, is made up of a .030 inch wire that holds a nickel-titanium coil spring and sliding hook. 13 A Nance holding arch ! Table 2.1: Tooth-Supported Distalizers Author Appliance Molar Crown Distal Movement (mm) Molar Crown Tipping Anchorage Loss (mm) __ __ __ 1.00 __ __ ( ̊) Premolar Tipping ( ̊) Gianelly17, 1991 NiTi Coils Bondemark et al19, 1994 Supercoils 11.5/mo 3.20 Ghosh & Nanda20, 1996 Pendulum 3.37 8.36 2.55 1.29 Huerter21, 1999 Distal Jet 3.1 5.6 2.1 1.3 Patel22, 1999 Distal Jet 1.9 2.2 2.8 -3 Bondemark23, 2000 NiTi Coils 2.50 8.80 1.20 2.10 Brickman et al24, 2000 Jones Jig 2.51 7.53 2.00 4.76 Kinzinger et al25, 2004 Pendulum K 3.14 3.07 __ __ Bussick & McNamara26, 2000 Pendulum 5.7 10.6 1.8 1.5 Chiu16, 2001 Distal Jet 3.0 5.0 2.5 0.3 Gutierrez27, 2001 Distal Jet 2.6 4.7 __ __ Lee28, 2001 Distal Jet 3.2 2.8 2.0 -2.3 Ngantuang et al29, 2001 Distal Jet 2.1 3.3 2.6 -4.3 Bolla30, 2002 Distal Jet 3.2 3.1 1.3 -2.8 Chiu et al16, 2005 Hilgers Pendulum Pendulum K 6.1 10.7 1.4 -1.7 3.85 4.18 1.08 -0.50 Kinzinger et al7, 2005 14 ! attached to either the first or second premolars or the primary molars with an acrylic palatal button makes up the anchorage unit. The appliance is inserted into the maxillary first molar at both the arch wire slot and headgear tubes.31 To activate the appliance the open-coil NiTi springs are compressed and tied back to the premolars in order to deliver a force of 70-75 g.15 According to Jones, rotated Class II corrections require 90-120 days to correct with the Jones Jig while true Class II molar relationships may take 120-180 days correct. Pendulum The Pendulum is a non-compliance appliance that is used for Class II malocclusion correction. In 1992, Hilgers explained this new mechanism as a way to deliver a light, continuous, distal force to the maxillary first molars.32 The Pendulum has a large Nance acrylic button against the palate for anchorage in combination with .032 inch TMA springs attached to the upper first molars. When activated, the appliance produces a broad, swinging arc of force from the midline of the palate to the maxillary molars. If the upper arch is narrow and expansion is indicated, a mid-palatal jackscrew can be 15 ! incorporated into the Nance button of the appliance. The form of the Pendulum appliance with an expansion screw is referred to as the “Pend-X.”32 The Pendulum has the advantage of being a noncompliant means of correcting a Class II molar relationship. It is easy to fabricate and insert, requiring only a single activation that can be adjusted via the activation springs, and is easily accepted by the patient.20 An inherent drawback, however, is anchorage loss that occurs with the premolars and anterior teeth as a result of the treatment. Distal Jet The Distal Jet is an appliance used for Class II correction independent of patient compliance (Fig 2.1.) It was introduced in 1996 by Carano and Testa33 as a method for distalizing maxillary molars without the disadvantages of tipping or rotation. The Distal Jet is composed of bilateral .036 inch tubes attached to a palatal Nance button. A NiTi coil spring and a screw clamp are placed over each of the tubes. Springs of either 150 g for children or 250 g for adults are customarily used. Wires attached to the Nance go through the tubes and end in a bayonet bend in order to be inserted into the lingual 16 ! sheaths of the first molar bands. Wires extending from the Nance button are soldered to premolar or deciduous molar bands to act as tooth-borne anchorage. The Distal Jet can be re-activated once a month by sliding the clamp closer to the first molar tube. Once the desired position of the molars is achieved, the appliance can be converted into a Nance retention device by covering the spring apparatus with composite or acrylic and cutting off the wires to the premolars.33 Fig 2.1: Original Distal Jet (Permission from Dynaflex) The Distal Jet is advantageous in that it allows near translatory distal movement of the maxillary molars. This is possible because the line of force is applied near the center of resistance of the molars. 17 The force is applied ! palatal to the center of resistance so a resulting drawback is mesial-palatal and distal-facial rotation.34 Several modifications and updates have been made to the Distal Jet since its introduction in order to make it easier to re-activate and to allow for better patient comfort and oral hygiene. Among the updates stated by Carano in 200235 are a new lock for improved function, a larger and more durable screw and activation wrench, a return to a single-screw design, and a longer barrel of the lock that allows for easier adjustments in order to correct molar rotations. These changes enabled the Distal Jet to be simple and efficient for the orthodontist and patient.35 While the introduction of the numerous non-compliance distalizers, of which the three above are examples, has introduced many advantages for maxillary molar distalization in orthodontic treatment, these methods are not free of shortcomings. Runge et al performed an analysis of rapid maxillary molar distal movement without patient cooperation using the Distal Jet and stated: The common finding of the significant mesial movement of the anchorage unit raises the question of true value in the “non-compliance” appliance category. To create excess overjet in a Class II case that has to be subsequently recovered introduces an element of insufficiency into the treatment.31 18 ! Miniscrew Implants as Anchorage Orthodontic anchorage is the foundation for successful tooth movement and is defined as the resistance to unwanted tooth movement.36 Skeletal anchorage by either direct or indirect anchorage is a way to achieve desired movements while avoiding unwanted side-effects and not depending on compliance. According to Proffit, anchorage involving implants largely improves the amount of true distal movement of the maxillary dentition that can be achieved, and allows for distalization of both the first and second molars. He also states that in some patients, up to 6 mm of distalization has been achieved using implant anchorage.1 The concept of osseointegration was introduced in the 1960s by Branemark, who found that bone was compatible with and had a high affinity for titanium.37 Retromolar and palatal osseointegrated implants were able to act as either direct or indirect anchorage during orthodontic treatment.37,38,39 These applications made it possible to apply orthodontic forces to accomplish tooth movement with less to no adverse effects. A temporary anchorage device (TAD) is defined by Cope40 as a device that is temporarily fixed to bone for the purpose of enhancing orthodontic anchorage either by 19 ! supporting the teeth of the reactive unit or by completely eliminating the need for a reactive unit, and then is removed after use. They can be fixed to the bone mechanically by being cortically stabilized, or they can be biochemically fixed by osseointegration. An additional category of anchorage where there is zero anchorage loss, infinite anchorage, is made possible due to the incorporation of dental implants and TADs.40 Implants, specifically miniscrew implants or TADs, have since been used for a variety of procedures in orthodontics including space closure, retraction, intrusion, extrusion, and distalization. The use of implants in orthodontics has allowed efficiency in treatment due to the stable anchorage and also because there are less if any corrections that need to be made due to anchorage loss. There is also enhanced predictability since patient compliance is often not a factor involved in accomplishing the treatment with implant-supported anchorage. Implant Supported Distalizers A systematic review of the literature was done by Fudalej41 in order to access studies on appliances reinforced with temporary skeletal anchorage devices. 20 The ! findings suggested that distalizing appliances that used skeletal anchorage had reduced unwanted side-effects compared to tooth-borne appliances. When miniscrew implants or miniplates were used as anchorage there was an increased amount of molar distalization while the maxillary incisors remained stable.41 A rationale for the greater movement is that there is a greater force applied to the molars with a bone anchored system because the miniscrews stay relatively stable in the bone. The distal force applied to molars in tooth-borne appliances, in contrast, is dissipated among the anchor teeth causing mesial movement. Even though the miniscrew supported appliances cause greater initial distalization, comprehensive treatment to retract anterior teeth and close spaces usually result in comparable amounts of distalization. Most of the studies in the review used non-integrated temporary skeletal anchorage devices (TSAD). Advantages of these compared to osseointegrated TSADs include immediate loading, simpler surgery, lower cost, and less discomfort for the patient.41 Temporary skeletal anchorage devices have been incorporated into several distalizing appliances in order to lessen or eliminate the anchorage loss that results using the conventional appliance. Table 2.2 summarizes the effects of some of these appliances. 21 ! Table 2.2: Implant-Supported Distalizers Author Appliance Molar Crown Distal Movement (mm) 3.9 Molar Crown Tipping ( ̊) Incisor/premolar movement (mm) " Gelgor42, 2004 Kircelli43, 2006 Escobar44, 2007 Kinzinger34, 2009 Oberti45, 2009 NiTi Coil Springs Pendulum 8.8 Incisors: 0.5 mesial 6.4 10.9 Pendulum 6.0 11.3 2nd pm: 5.4 distal, 1st pm: 3.8 distal 2nd pm: 4.85 distal Distal Jet 3.92 __ ! ! ! ! ! ! ! Dual-Force Distalizer 5.9 5.6 2nd pm: 1.87 distal, 1st pm: 0.78 mesial 2nd pm: 4.26 distal Distal Jet Tooth-Supported Distal Jet The Distal Jet has become a popular appliance among the options for Class II correction due to its numerous advantages. It can be used for unilateral or bilateral correction, is relatively simple to insert, is well tolerated and esthetic, and does not rely on patient compliance. The Bowman Modification of the Distal Jet appliance replaces the tube/piston assembly with a U-shaped tracking wire (Fig 2.2.)46 This is supported by bands on the maxillary first molars and is either banded to, or rests on, the premolars. The occlusal rests are bonded in place 22 ! and may act as a bite opening mechanism during distalization. There are two sets of collars bilaterally on the tracking wire. The mesial collar is moved distally against the super elastic coil spring to cause activation. The distal collar is released only 1/8 a turn in order to allow distal translation of the molars. When activation is complete the distal stop collars on the tracking wire are locked. This allows for easy conversion to a Nance holding arch since the coil springs do not have to be removed.46 Fig 2.2: Bowman Modification Distal Jet with tracking wire and collars (photo courtesy of Dr. S. Jay Bowman)47 Bolla et al30 performed a retrospective study on 20 subjects that were treated with the Distal Jet to correct a Class II dental malocclusion. The aim was to analyze the effects of the Distal Jet alone, without fixed orthodontic appliances bonded to the teeth. 23 Generally, the Distal Jet ! studies include subjects that simultaneously have brackets bonded to the maxillary dentition during distalization. An early report by Gutierrez27 stated that there was greater distal movement of the upper first molar when the Distal Jet was used alone (3.7 mm vs 2.6 mm). There were 7.3⁰ of distal tipping of the molar which was more than the 4.7⁰ that occurred when distalization occurred with appliances in place. A more dramatic finding was the amount of upper incisor proclination that resulted from using the Distal Jet with brackets in place compared to the Distal Jet alone (12.3⁰ vs 2.2⁰).27’30 ! The investigation by Bolla on the effects of the Distal Jet alone obtained results from measuring pre- and post-distalization lateral cephalometric radiographs and dental casts. The measurements were comparable to other reports in the literature on the Distal Jet and can be found in Table 2.1. Ngantung et al29 did an evaluation on the Distal Jet appliance in order to investigate not only postdistalization effects, but also post-treatment effects. The thirty-three patients were treated with the Distal Jet during full-bracketed appliance therapy. Post- distalization effects can be found in Table 2.1 among the 24 ! results of the similar distalizing appliances. The post- treatment effects showed a 1.82 mm net mesial movement of the upper first molar. The Class I molar relationship that was achieved with distalization was sustained due to the 4.8 mm net mesial change of the lower first molar. Ngantung stated that it was difficult to differentiate the effects of treatment from the effects of growth.29 The maxillary incisor to SN angle increased an average of 5.3⁰ at the completion of treatment. The mentioned studies come to a similar conclusion about the tooth-supported Distal Jet. The appliance is successful at distalizing upper first molars to correct a Class II malocclusion, but not without adverse anchorage loss in the premolars and incisors. Miniscrew Implant Supported Horseshoe Distal Jet Bowman described the miniscrew anchorage supported Horseshoe Jet (Fig 2.3) as an appliance that relies solely on palatal miniscrews for anchorage. This form of the Distal Jet is supported by skeletal anchorage. Thus, it removes dental or palatal vault anchorage and subsequent anchorage loss. The forces applied to cause distal movement of the molars are the same as the original Distal 25 ! Jet, close to the center of resistance in order to cause less unwanted tipping.47 Miniscrew implants can be incorporated into the Horseshoe Jet by attaching the screws to hooks on the anterior part of the tracking wire with steel ligature wires. The mechanism of attachment allows any screw size to be used. Successfully utilized screws have included 1.5 – 2 mm in diameter and 6 – 8 mm in length. The miniscrews are placed under local anesthesia in a palatal position between the second premolar and first molar. The Horseshoe Jet is cemented into place and bonding adhesive is applied or ligature wires are secured tightly to the miniscrews. The distal set screws are unlocked a quarter turn to allow distal movement along the tracking wire. Subsequently, the mesial set screws are unlocked and moved toward the molars in order to activate the super-elastic coil spring and then locked again. Evaluation of the distalization is noted every four weeks and re-activation is performed at this time until the desired position is achieved. When distalization is complete, the distal set screws are locked into place and the appliance acts as anchorage control as the anterior teeth are retracted.47 26 ! Fig 2.3: Miniscrew implant supported Distal Jet (photo courtesy of Dr. S. Jay Bowman)48 The goal of the miniscrew implant (MI) supported Distal Jet is to diminish or lessen to a large degree the anchorage loss experienced with conventional tooth-borne distalizers. It consists of only the horseshoe wire and lacks the support arms to the premolars, therefore utilizing pure skeletal anchorage. The distal force is applied to the molars and any reciprocal force is dissipated to the miniscrews. Since the premolars are not attached to the appliance, they tend to follow the molars due to the stretching and pulling of the transseptal fibers. Cautious miniscrew implant placement is necessary in order to avoid any interference of roots with the anticipated movements. 27 ! After the desired position of the molars is achieved, the appliance is conveniently converted to an indirect MI supported anchorage device by locking the distal-set screws. The appropriate retraction mechanics can then be applied to the maxillary teeth.48 Measuring Class II Correction It is beneficial to know if the orthodontic treatment rendered to a patient was successful or not. In order to see the effects of treatment, the skeletal and dental changes must be measured. These measurements are especially important when there was an attempt at anteroposterior correction. When a Class II malocclusion is corrected with treatment it is beneficial to know where the correction came from. It may be a result of restricting the maxilla, distalizing the maxillary molars, forward movement of the mandibular dentition, forward growth of the mandible, or a combination of these. The type of movement will depend on the orthodontist’s goals of treatment and the treatment modality. Cephalometric radiographs capture both skeletal and dental information. Johnston49 explains that the method of measuring change due to treatment and/or growth involves some form of superimposition that consists of registration 28 ! and orientation. To measure only bodily displacement without the component of remodeling, the registration and orientation must be based on stable reference structures. Johnston describes a method of cephalometric analysis that accounts for anteroposterior change measured at the level of the occlusion. This ‘pitchfork diagram’ summarizes correction of malocclusion by measuring the changes in molar relationship and overjet. The superimposition of the cephalometric radiographs reveals a series of physical displacements produced by growth and tooth movement: displacement of maxilla relative to cranial base, movement of maxillary dentition relative to maxillary basal bone, translation of mandible relative to cranial base, and movement of mandibular dentition relative to mandibular basal bone.49 Measuring these changes on pre-treatment and post-treatment cephalometric radiographs can show the causes of the correction. In the ‘pitchfork diagram’ the displacements are given positive or negative values based on the contribution to the Class II correction. A positive value is given to movements that correct a Class II, such as forward mandibular growth, mesial mandibular molar movement, or a reduction in overjet. A negative value is applied if the movement increases the Class II molar relationship or increases the overjet. 29 The change in molar ! relationship and overjet can then be discovered from the algebraic sum of the skeletal and dental movements. Johnston’s ‘pitchfork diagram’ is able to show treatment changes with respect to both magnitude and source, providing a summary of the various components of change that occur at the occlusal plane.49 Statement of Thesis The aim of this investigation is to compare the effects of a tooth-supported Distal Jet and miniscrew implant (MI) supported Distal Jet at the completion of orthodontic treatment. Several studies have investigated the dental effects of a Distal Jet and similar appliances immediately after distalization. Numerous studies have also reported findings on implant supported maxillary molar distalizers. Few have compared and contrasted the difference in final treatment results between a toothsupported distalizer and implant supported distalizer. The current study will specifically examine the Distal Jet, both tooth-supported and MI supported, with successive fixed orthodontic appliances. The final treatment results will then be compared to examine if there are differences in amount of maxillary molar distal movement or distal tipping, anterior movement of incisors, and treatment time. 30 ! REFERENCES 1. Proffit WR, Fields HW, Sarver DM. Contemporary Orthodontics. 4th ed. St. Louis, MO: Mosby Elsevier, 2007. 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. Thilander B, Pena L, Infante C, Parada SS, Mayorga C. Prevalence of malocclusion and orthodontic treatment need in children and adolescents in Bogota, Colombia. An epidemiological study related to different stages of dental development. Eur J Orthod. 2001;23:153–68. 4. Gelgör IE, Karaman AI, Ercan E. Prevalence of malocclusion among adolescents in central anatolia. Eur J Dent. 2007;1:125-31. 5. Phelan T, Buschang PH, Behrents RG, Winterqerst AM, Ceen RF, Hernandez A. Variation in Class II malocclusion: Comparison of Mexican mestizos and American whites. Am J Orthod and Dentofacial Orthop. 2004;125:418–25. 6. McNamara JA Jr. Components of Class II malocclusion in children 8-10 years of age. Angle Orthod. 1981;51:177–202. 7. Kinzinger GSM, Eren M, Diedrich PR. Treatment effects of intraoral appliances with conventional anchorage designs for non-compliance maxillary molar distalization: a literature review. Eur J Orthod. 2008;30:558–71. 8. Craig CE. The skeletal patterns characteristic of Class I and Class II, Division I malocclusions in norma lateralis. Angle Orthod. 1951;21:44-56. ! ! ! ! ! ! ! ! 31 ! 9. Schaefer AT, McNamara JA Jr, Franchi L, Baccetti TA. Cephalometric comparison of treatment with the Twinblock and stainless steel crown Herbst appliances followed by fixed appliance therapy. Am J Orthod Dentofacial Orthop. 2004;126:7–15. ! 10. Wieslander L, Tandläkare L. The effect of orthodontic treatment on the concurrent development of the craniofacial complex. Am J Orthod. 1963;49:15–27. ! 11. McDonald FT. The influence of age on patient cooperation in orthodontic treatment. Dent Abstr. 1973;18:52. ! 12. Weiss J, Eiser HM. Psychological timing of orthodontic treatment. Am J Orthod. 1977;72:198–204. ! 13. Skidmore KJ, Brook KJ, Thomson WM, Harding WJ. Factors influencing treatment time in orthodontic patients. Am J Orthod Dentofacial Orthop. 2006;129: 230–38. ! 14. Nanda RS, Kierl MJ. Prediction of cooperation in orthodontic treatment. Am J Orthod Dentofacial Orthop. 1992;102:15–21. ! 15. McSherry PF, Bradley H. Class II Correctionreducing patient compliance: a review of the available techniques. J Orthod. 2000;27:219–25. (2000). ! 16. Chiu PP, McNamara JA Jr, Franchi LA. Comparison of two intraoral molar distalization appliances: Distal jet versus Pendulum. Am J Orthod Dentofacial Orthop. 2005;128:353–65. ! ! 32 ! 17. Gianelly AA, Bednar J, Dietz VS. Japanese NiTi coils used to move molars distally. Am J Orthod Dentofacial Orthop. 1991;99:564–66. ! 18. Jones RD, White JM. Rapid Class II molar correction with an open-coil jig. J Clin Orthod. 1992;26:661–64. ! 19. Bondemark L, Kurol J, Bernhold M. Repelling magnets versus superelastic nickel-titanium coils in simultaneous distal movement of maxillary first and second molars. Angle Orthod. 1994;64:189–98. ! 20. Ghosh J, Nanda RS. Evaluation of an intraoral maxillary molar distalization technique. Am J Orthod Dentofacial Orthop. 1996;110:639–46. ! 21. Huerter GWJ. A retrospective evaluation of maxillary molar distalization with the Distal Jet appliance. Saint Louis University;1999. Masters Degree Thesis. St. Louis, MO. ! 22. Patel AN. Analysis of the Distal Jet appliance for maxillary molar Distalization. University of Oklahoma;1999. Masters Degree Thesis. Oklahoma City, OK. ! 23. Bondemark L. A comparative analysis of distal maxillary molar movement produced by a new lingual intra-arch Ni-Ti coil appliance and a magnetic appliance. Eur J Orthod. 2000;22:683–95. ! 24. Brickman CD, Sinha PK, Nanda RS. Evaluation of the Jones Jig appliance for distal molar movement. Am J Orthod Dentofacial Orthop. 2000;118:526–34. ! ! ! 33 ! 25. Kinzinger G, Syrée C, Fritz U, Diedrich P. Molar distalization with different pendulum appliances: in vitro registration of orthodontic forces and moments in the initial phase. J Orofac Orthop. 2004;65:389– 409. ! 26. Bussick TJ, McNamara JA Jr. Dentoalveolar and skeletal changes associated with the pendulum appliance. Am J Orthod Dentofacial Orthop. 2000;117: 333–43. ! 27. Gutierrez VME. Treatment effects of the Distal Jet appliance with and without edgewise therapy. Saint Louis University;2001. Masters Degree Thesis. St. Louis, MO. ! 28. Lee S. Comparison of the Treatment Effects of Two Molar Distalization Appliances. Saint Louis University;2001. Masters Degree Thesis. St. Louis, MO. ! 29. Ngantung V, Nanda RS, Bowman SJ. Posttreatment evaluation of the distal jet appliance. Am J Orthod Dentofacial Orthop. 2001;120:178–85. ! 30. Bolla E, Muratore F, Carano A, Bowman SJ. Evaluation of maxillary molar distalization with the distal jet: a comparison with other contemporary methods. Angle Orthod. 2002;72:481–94. ! 31. Runge ME, Martin JT, Bukai F. Analysis of rapid maxillary molar distal movement without patient cooperation. Am J Orthod Dentofacial Orthop. 1999;115:153–57. ! 32. Hilgers JJ. The pendulum appliance for Class II non-compliance therapy. J Clin Orthod. 1992;26:706– 14. ! ! 34 ! 33. Carano A, Testa M. The distal jet for upper molar distalization. J Clin Orthod. 1996;30:374–380. ! 34. Kinzinger GSM, Gülden N, Yildizhan F, Diedrich PR. Efficiency of a skeletonized distal jet appliance supported by miniscrew anchorage for noncompliance maxillary molar distalization. Am J Orthod Dentofacial Orthop. 2009;136:578–86. ! 35. Carano A, Testa M, Bowman SJ. The distal jet simplified and updated. J Clin Orthod. 2002;36:586– 90. ! 36. Justens E, De Bruyn H. Clinical outcome of miniscrews used as orthodontic anchorage. Clin Implant Dent Relat Res. 2008;10:174–80. ! 37. Wahl N. Orthodontics in 3 millennia. Chapter 15: Skeletal anchorage. Am J Orthod Dentofacial Orthop. 2008;134:707–10. ! 38. Roberts E. Rigid endosseous implants for orthodontic and orthopedic anchorage. Angle Orthod. 1989;59:24756. 39. Wehrbein H, Merz BR, Diedrich P, Glatzmaier J. The use of palatal implants for orthodontic anchorage. Design and clinical application of the orthosystem. Clin Oral Implants Res. 1996;7:410–16. ! 40. Cope JB. Temporary anchorage devices in orthodontics: A paradigm shift. Sem Orthod. 2005;11: 3–9. ! 41. Fudalej P, Antoszewska J. Systematic review: Are orthodontic distalizers reinforced with the temporary skeletal anchorage devices effective? Am J Orthod Dentofacial Orthop. 2011;139:722–29. ! ! 35 ! 42. Gelgör IE, Büyükyilmaz T, Karaman AIY, Dolanmaz D, Kalayci A. Intraosseous screw-supported upper molar distalization. Angle Orthod. 2004;74:838–50. ! 43. Kircelli BH, Pektaş ZO, Kircelli C. Maxillary molar distalization with a bone-anchored pendulum appliance. Angle Orthod. 2006;76:650–59. ! 44. Escobar SA, Latorre CM, molars with study. Am J 49. Tellez PA, Moncada CA, Villegas CA, Oberti G. Distalization of maxillary the bone-supported pendulum: A clinical Orthod Dentofacial Orthop. 2007;131:545– ! 45. Oberti G, Villegas C, Ealo M, Palacio JC, Baccetti, T. Maxillary molar distalization with the dual-force distalizer supported by mini-implants: A clinical study. Am J Orthod Dentofacial Orthop. 2009;135:282– 83. ! 46. Kinzinger GSM, Diedrich PR, Bowman SJ. Upper molar distalization with a miniscrew-supported Distal Jet. J Clin Orthod. 2006;40:672–78. ! 47. Bowman SJ. Distal Jets refined: Bowman modification and Horseshoe Jet. AOAppliances. 2008;1–5. ! 48. Bowman SJ. Miniscrew implant molar distalization: Evolution of the horseshoe Jet. Papadopoulos MA (Ed). Skeletal Anchorage in Orthodontic Treatment of Class II Malocclusion: Contemporary Applications of Orthodontic Implants, Miniscrew Implants and Mini Plates. (Mosby Ltd.:In Press). ! 49. Johnston LE Jr. Balancing the books on orthodontic treatment: an integrated analysis of change. Br J Orthod. 1996;23:93–102. 36 ! CHAPTER 3: JOURNAL ARTICLE Abstract Purpose: The objective of this study is to evaluate and compare the final treatment skeletal and dental effects of the conventional tooth-supported Distal Jet and the miniscrew implant (MI) supported Horseshoe Distal Jet appliance using lateral cephalometric radiographs of previously treated patients. Information about treatment time will be used to determine if there is a difference in the amount of time required to treat patients with the different appliances. Materials and Methods: Lateral cephalometric radiographs of Class II patients treated with the Distal Jet appliance were obtained from a single practice. The sample was divided into two groups of 27 patients based on the type of Distal Jet used for treatment. The subjects were placed in either a tooth-supported Distal Jet group or a miniscrew implant (MI) supported Horseshoe Distal Jet1 group. inclusion criteria for subject selection were: The (1) pre- treatment Class II malocclusion, (2) no permanent teeth extracted (excluding third molars), (3) diagnostic quality lateral cephalometric radiographs pre- and post-treatment, 37 ! (4) the use of the Distal Jet for molar distalization, followed by fixed orthodontic appliances, and (5) bilateral distalization. Pre-treatment (T1) and post-treatment (T2) lateral cephalometric radiographs were obtained for each subject. The pre-treatment and post-treatment tracings were then superimposed using the Pitchfork analysis and measured with electronic vernier calipers.2 The angular changes of the first molars and anterior incisors were measured relative to the mean functional occlusal plane. An independent two- sample t-test was performed to compare the two groups and differences were considered statistically significant at p < .05. Results: The tooth-supported Distal Jet group and the MI supported Distal Jet group both showed a mesial trend in movement of the maxilla and mandible. At the end of comprehensive orthodontic treatment, the upper molar in both groups had a slight distal movement. The difference in lower molar change was significant with the tooth-supported Distal Jet group having a greater contribution to molar correction with more mesial movement. The difference in overall molar correction was insignificant. The change in upper incisor movement and angulations between the two 38 ! groups was not significant. The MI supported group had a distal movement of the lower incisors which was a significant difference from the mesial movement of the tooth-supported group. The overjet change was very similar between the groups and of no significance. Treatment time in the tooth-supported group was 1.6 months longer than the MI supported group. Conclusions: (1) Class II treatment with the tooth- supported Distal Jet or miniscrew implant supported Distal Jet followed by fixed orthodontic appliances does not show any advantage for either maxillary molar distalizing appliance. (2) The final effects of Class II molar correction and overjet in the groups were similar with no significant difference. (3)Difference in total treatment time with the two types of Distal Jet is not significant. 39 ! Introduction Class II malocclusions are frequent in the general population. In 1998, the third National Health and Nutrition Examination Survey3 reported that a Class II malocclusion occurred in 23% of children, 15% of youths, and 13% of adults.4 Class II malocclusions are treated by several different techniques. The choice of treatment method is dependent on many factors, some of which include: the patient’s age, the amount of jaw discrepancy, the severity of the Class II molar relationship, the amount of space available in the arch, and the compliance of the patient. In treating Class II malocclusions, molar distalization has been among the preferred methods of non-extraction treatment. There are several means of distalizing treatments, with both patient compliance non-compliance methods. The methods that are independent of patient compliance are usually more favorable due to greater predictability. The Distal Jet is a fixed appliance that is independent of patient compliance. The conventional Distal Jet customarily utilizes bands on the maxillary first molars and first premolars, with a palatal Nance button. 40 ! Due to the dentoalveolar support of the appliance, the distalization of the first molars results in opposite tooth movements anterior to the first molars. The literature reports that the effects of the Distal Jet include: first molar distalization and distal tipping, mesial movement and mesial tipping of the first and/or second premolars, incisor proclination, an increase in lower anterior face height, and a minor increase in FMA.5 Some of these effects have to be compensated for after distalization in order to achieve ideal results. The miniscrew implant (MI) supported Horseshoe Distal Jet described by Bowman1 introduces an anchorage strategy where the reciprocal forces from distalizing the molars are placed on the MI and supporting bone instead of the dentition. Therefore, there should be less anchorage loss in anterior teeth and incisor proclination. If few or no dental compensations are produced after distalization, overall treatment time is expected to be shorter. This study will focus on evaluating the final treatment differences between two groups of Class II patients treated with either a tooth-supported Distal Jet or a miniscrew implant supported Horseshoe Distal Jet. 41 ! Materials and Methods Sample The data in this retrospective clinical study was obtained from lateral cephalometric radiographs of Class II patients treated with Distal Jet appliances. The sample was divided into two groups based on the type of Distal Jet used for treatment (Table 3.1). The subjects were placed in either a tooth-supported Distal Jet group (Group 1) or a miniscrew implant (MI) supported Horseshoe Distal Jet6 group (Group 2). The patients were selected from the office of a single practicing orthodontist and the lateral cephalometric radiographs were from the same imaging device. The inclusion criteria for subject selection were: (1) pre-treatment Class II malocclusion, (2) no permanent teeth extracted (excluding third molars), (3) diagnostic quality lateral cephalometric radiographs pre- and posttreatment, (4) the use of the Distal Jet for molar distalization, followed by fixed orthodontic appliances, and (5) bilateral distalization. 42 ! Table 3.1: Characteristics of sex and age-matched samples ! Males Females Mean Initial Age " Tooth Supported 10 17 13 y 2 mo " MI Supported 10 17 12 y 8 mo Group 1 was composed of 27 patients (17 females, 10 males) treated with the conventional Distal Jet. The distalization was accomplished with the Bowman modification6 of the Distal Jet where the tube and piston is replaced with a rigid tracking wire and two locking collars. Group 2 consisted of 27 patients (17 females, 10 males) treated with the MI supported Horseshoe Distal Jet. Brackets were bonded to the lower arch in both groups during distalization to initiate leveling. Once the desired amount of distalization was achieved in the Bowman modification, the Distal Jet was converted into a holding arch by locking the distal set screws along the tracking wire and sectioning the wires attached to the premolars. The original Distal Jet was converted to a modified Nance holding arch by cutting the wires attached to the premolars and removing the open coil spring. supported Horseshoe Jet was simply converted into an indirect MI supported anchorage system by locking the 43 The MI ! distal-set screws. It then provided skeletal anchorage for subsequent retraction mechanics of the maxillary anterior teeth. Class II elastics were utilized when required. Data Collection Pre-treatment (T1) and post-treatment (T2) lateral cephalometric radiographs were obtained for each subject. Each radiograph was hand-traced on acetate paper with a 0.3 mm pencil by a single investigator. The pre-treatment and post-treatment tracings were then superimposed using the Pitchfork Analysis. This method described by Johnston2 is a cephalometric analysis that accounts for anteroposterior change measured at the level of the mean functional occlusal plane. The mean functional occlusal plane is constructed by averaging the T1 and T2 functional occlusal planes. This ‘pitchfork diagram’ (Figure 3.1) summarizes correction of malocclusion by measuring the changes in molar relationship and overjet. The superimposition of the cephalometric radiographs reveals a series of physical displacements produced by growth and tooth movement: displacement of the maxilla relative to cranial base, movement of maxillary dentition relative to maxillary basal bone, translation of mandible relative to cranial base, and movement of mandibular dentition relative 44 ! to mandibular basal bone.2 Measuring these changes on pre- treatment and post-treatment cephalometric radiographs can show the components of the correction. In the ‘pitchfork diagram’ the displacements are given positive or negative values based on the contribution to the Class II correction. A positive value is given to movements that correct a Class II, and a negative value is applied if the movement increases the Class II molar relationship or increases the overjet. The change in molar relationship and overjet can then be discovered from the algebraic sum of the skeletal and dental movements. Johnston’s ‘pitchfork diagram’ is able to show treatment changes with respect to both magnitude and source, providing a summary of the various components of change that occur at the mean functional occlusal plane. The measurements were carried out with electronic vernier calipers to the nearest tenth of a millimeter.2 The dental and skeletal anteroposterior changes were measured and accounted for using the Pitchfork analysis. The Distal Jet also causes angular changes in the first molars and anterior teeth during maxillary molar distalization. The angulations were measured by hand relative to the mean functional occlusal plane. 45 ! MAX + MAND = ABCH ABCH + U6 + L6 = 6/6 ABCH + U1 + L1 = 1/1 Fig 3.1: Pitchfork analysis diagram, adapted from Johnston2 Pre-treatment lateral cephalometric radiographs were evaluated for eruption of maxillary second molars, presence of mandibular primary second molars, angular measurements (SNA, SNB, ANB) to determine initial severity of skeletal Class II, and interincisal angle (Table 3.2). 46 ! Table 3.2: Samples defined at pre-treatment Group 1 Group 2 Subjects with MAX 2nd molars erupted 14 21 Subjects with MN primary 2nd molars present 4 6 Mean SNA (⁰) 80.85 83.15 Mean SNB (⁰) 77.26 78.56 Mean ANB (⁰) 3.63 4.59 Interincisal Angle (⁰) 134.19 131.15 Statistical Methods Analysis was completed using statistical software SPSS 20.0 for Windows. Levene’s test was used before the comparison of means to assess the equality of variances. An independent two-sample t-test was performed on the two groups and differences were considered statistically significant at p < .05. The Cronbach’s Alpha test was performed to evaluate intra-examiner reliability. The lateral cephalometric radiographs from 10% of the original sample were re-traced 47 ! and superimposed. The intraclass correlation coefficients of the measurements ranged from 0.68-0.92. Results The final treatment effects of the tooth-supported Distal Jet and the MI supported Horseshoe Distal Jet can be found in Table 3.2. The pitchfork analysis for the tooth- supported Distal Jet (Group 1) revealed a mean measurement of -2.48 mm for the maxilla. This indicates a forward movement of the maxilla relative to the cranial base. The MI supported Horseshoe Jet (Group 2) had a mean measurement of -3.10 for the maxilla. Both groups had mesial movement of the maxilla and the small difference between the two groups was not significant. The mean change of the mandible after treatment was a forward movement for both groups. Group 1 had a 3.58 mm change and Group 2 showed a 4.03 mm change. The difference in the amount of mesial movement between the groups was significant, however, the reliability score for this measurement was low. The mean apical base change (ABCH), or the growth/displacement of the mandible relative to the maxillary basal bone, exhibited a positive contribution to 48 ! the anteroposterior correction in both groups. The difference between the tooth-supported group (1.09 mm) and MI supported group (3.23 mm) was statistically significant. There was distal movement and distal tipping of the upper molar in both groups (0.25 mm, 0.52⁰ in Group 1 and 0.45 mm, 2.00⁰ in Group 2.) These results were similar and not significant. There was a significant difference in the amount of lower molar measurement between the two groups. The tooth- supported group had a mesial movement (mean 1.25 mm) and the MI supported group showed a distal movement (mean -0.52 mm). The mean total molar correction was not significant at 2.59 mm in Group 1 and 3.15 mm in Group 2. The upper incisor mean change was a 0.42 mm in Group 1 and -0.27 mm Group 2. These results show a slight distal movement in the tooth-supported group and a mesial movement in the MI supported group, but the small difference was not significant. There was upper incisor proclination in both groups (5.15⁰ in Group 1 and 7.93⁰ in Group 2.) The difference in lower incisor change between groups was significant. Group 1 had a mean change of 0.91 mm while Group 2 had a mean change of -0.31. 49 The lower ! incisor moved forward in Group 1, whereas it moved distal in Group 2. The amount of overjet correction was similar among the groups and not significant (2.42 mm in Group 1, 2.63 mm in Group 2). The mean treatment time for the tooth-supported group was 30.11 months and 28.48 months for the MI supported group. The 1.6 month longer treatment in the tooth- supported groups is insignificant. Fig 3.2: Pitchfork summary of treatment changes. (A) Treatment changes in Group 1 (B) Treatment changes in Group 2 50 ! Table 3.3: Comparison of sex and age-matched individuals with Tooth- Supported and MI Supported Distal Jet appliances Tooth-supported Distal Jet MI supported Distal Jet Mean SD Mean SD Sig ABCH (mm) 1.09 1.97 3.23 2.89 .003* MAX (mm) -2.48 1.99 -3.10 1.86 .241 MAND (mm) 3.58 3.20 6.33 4.03 .008* U6 (mm) 0.25 1.53 0.45 2.15 .703 L6 (mm) 1.25 1.68 -0.52 1.70 .000* U6/L6 (mm) 2.59 1.21 3.15 1.81 .186 U1 (mm) 0.42 2.26 -0.27 3.22 .365 L1 (mm) 0.91 1.81 -0.31 2.47 .043* U1/L1 (mm) 2.42 2.51 2.63 2.46 .750 Distal Tipping of U6 (⁰) 0.52 3.69 2.00 4.10 .169 Flaring of U1 (⁰) 5.15 8.72 7.93 10.96 .307 Treatment Time (months) 30.11 4.80 28.48 4.29 .194 * Statistically significant: p value ≤0.05 51 ! Discussion The Distal Jet appliance has been shown to be a successful and efficient method of distalizing maxillary molars to correct a Class II malocclusion. The literature reports that it is capable of causing almost pure translatory distal movement of the upper molars.7 The inherent shortcoming to the conventional appliance is the anchorage loss that occurs due to the reciprocal forces from the distalization. The majority of previous studies done on the Distal Jet provide post-distalization data. The data in this present study are from pre- and post-treatment cephalometric tracings of a tooth-supported Distal Jet (Group 1, mean initial age 13y 2mo) and a MI supported Distal Jet (Group 2, mean initial age 12y 8mo.) The amount of distalization produced immediately after the Distal Jet was not compared. Instead, the final results of comprehensive treatment (Table 3.2) utilizing two forms of the Distal Jet appliance to correct the Class II relationship were evaluated to determine if there are differences in skeletal effects, dental effects and treatment time. It should be noted that, when necessary, Class II elastics were utilized in both groups during 52 ! treatment to help correct or maintain position of molars during anterior tooth retraction. Gianelly8 suggests that if overjet increases greater than two millimeters during distalization with the Distal Jet the addition of headgear or elastics should be initiated. Skeletal Changes In this study the mean maxillary movement relative to the cranial base (MAX) was -2.48 mm for the tooth-supported group and -3.10 for the MI supported group. The negative value in the pitchfork analysis indicates a forward movement of the maxilla in both groups. This is representative of the normal pattern of growth for the maxilla. The amount of maxillary change was similar for the groups and not significant. In the pitchfork analysis the mandibular change relative to the cranial base (MAND) is calculated from the measurements of MAX and ABCH. The mandible had a mesial movement in both groups (Group 1, 3.58 mm; Group 2, 6.33 mm), and the differences were significant. Again, this follows the normal forward pattern of growth/displacement for the mandible. The ABCH difference was also significant at 1.09 mm for Group 1 and 3.23 mm for Group 2. A positive number denotes that the mandible 53 ! outgrows the maxilla. The greater apical base change in Group 2 may be related to the greater mean initial ANB angle compared to Group 1 pre-treatment (Group 1 ANB: 3.63⁰, Group 2 ANB: 4.59⁰). Although the results showed significance, the intraclass correlation coefficient for the MAND measurements was low and therefore these comparisons may be unreliable. Dental Changes Distal movement and distal tipping of the upper molars in both groups (0.25 mm, 0.52⁰ in Group 1 and 0.45 mm, 2.00⁰ in Group 2) were noted. The angular measurements were measured relative to the mean functional occlusal plane. It must be noted that these measurements reflect the amount of movement after comprehensive treatment instead of postdistalization. The amount of maxillary molar distalization that took place in past studies of the Distal Jet ranged from 1.9 – 3.2 mm with 2.2⁰ – 5.6⁰ of distal tipping.5,9-14 The findings in this study (Group 1: 0.25 mm, 0.52⁰; Group 2: 0.45 mm, 2.00⁰ ) represent the position of the molars after retraction of the anterior teeth, where the upper molars tend to move mesially. 54 ! The difference in the amount of upper molar movement between the two groups was not significant. A control group with an average initial age of 9-12 years in a previous study was analyzed with the pitchfork analysis over a two-year time period.15 The amount of upper molar movement in this untreated group was a mean of -1.1 mm, signifying a mesial movement. When compared to the results of this study, the upper molars in the Distal Jet groups were located in a slightly more distal position. The lower molar moved mesially (mean 1.25 mm) in Group 1, but moved distally (mean -0.52 mm) in Group 2. This difference was significant. The lower molar movement in the MI supported group was in accordance with the lower molar movement of the previously mentioned control group (mean -0.6 mm).15 Class II elastics may have been needed to a greater extent in the tooth-supported Distal Jet group to control the amount of anterior tooth mesial movement, and therefore, may have contributed to the significantly greater amount of mesial lower molar movement. The amount of initial crowding or spacing and stage of dental development may also play a role in the movement of the lower molar. 55 ! The total Class II mean molar correction was 2.59 mm in Group 1 and 3.15 mm in Group 2. The MI supported Horseshoe Jet showed slightly greater amount of molar change, however not significant. This could be due to the slightly greater amount of distal movement of the upper molar in the MI group and the fact that there is skeletal anchorage during retraction. The amount of anchorage loss is commonly measured in the anterior teeth. The direct amount of anchorage loss is difficult to quantify in a post-treatment study since the anterior teeth have been orthodontically retracted into the created spaces. There was a distal movement (mean 0.42 mm) of the upper incisor in Group 1, and a mesial movement (mean -0.27 mm) in Group 2. More retraction occurred in Group 1 compared to Group 2, but the differences will not significant. There was upper incisor proclination in both groups (5.15⁰ in Group 1 and 7.93⁰ in Group 2) and these differences were also not significant. The lower incisor moved mesial in Group 1 (mean 0.91 mm) and distal in Group 2 (mean -0.31 mm). These differences were considered significant and may be due to the amount of initial crowding and overjet, or the amount of Class II elastic wear. 56 ! Group 1 had 2.42 mm total overjet correction, and Group 2 had 2.63 mm of correction. Even though there was more overjet correction in the MI supported group, the upper incisors moved mesial more and flared more than the tooth-supported group, but the differences were insignificant. This may be influenced by the initial amount of flaring and the amount of retraction accomplished. The mean treatment time for the tooth-supported group was 30.11 months and 28.48 months for the MI supported group. The treatment time was approximately 1.6 months shorter for the MI supported group, a difference not considered significant. Conclusions 1. Class II treatment with the tooth-supported Distal Jet or miniscrew implant supported Distal Jet followed by fixed orthodontic appliances does not demonstrate any advantage for either maxillary molar distalizing appliance. 2. The final effects of Class II molar correction and overjet in the groups were similar with no significant difference. 57 ! 3. Difference in total treatment time with the two types of Distal Jet is not significant. 58 ! Appendix Table A.1: Description of pitchfork analysis cephalometric variables Abbreviation Definition ABCH Mandibular displacement relative to maxillary basal bone, measured at D point (geometric center of symphysis) Skeletal Change Maxilla MAX Mandible MAND Upper Molar Lower Molar Molar Change Upper Incisor Lower Incisor Overjet Maxillary displacement relative to cranial base, measured at wing point Mandibular displacement relative to cranial base (ABCH-MAX) U6 Maxillary first molar displacement relative to the basal bone, measured at mesial contact point L6 Mandibular first molar displacement relative to the basal bone, measured at mesial contact point 6/6 Molar relation change, measured by registering on mesial contact points of U6 and measuring the separation of mesial contact points of L6 U1 Maxillary incisor displacement relative to basal bone, measured at incisal edge L1 Mandibular incisor displacement relative to basal bone, measured at incisal edge 1/1 Overjet correction, measured by registering on incisal edges of U1 and measuring the separation of incisal edges of L1 59 ! References 1. Bowman SJ. Miniscrew implant molar distalization: Evolution of the horseshoe Jet. Papadopoulos MA (Ed). Skeletal Anchorage in Orthodontic Treatment of Class II Malocclusion: Contemporary Applications of Orthodontic Implants, Miniscrew Implants and Mini Plates. (Mosby Ltd.:In Press). 2. Johnston LE Jr. Balancing the books on orthodontic treatment: an integrated analysis of change. Br J Orthod. 1996;23:93–102. 3. Proffit, W. R., Fields, H. W., Jr & Moray, L. J. Prevalence of malocclusion and orthodontic treatment need in the United States: estimates from the NHANES III survey. Int J Adult Orthodon Orthognath Surg 13, 97–106 (1998). 4. Proffit WR, Fields HW, Sarver DM. Contemporary Orthodontics. 4th ed. St. Louis, MO: Mosby Elsevier, 2007. 5. Bolla E, Muratore F, Carano A, Bowman SJ. Evaluation of maxillary molar distalization with the distal jet: a comparison with other contemporary methods. Angle Orthod. 2002;72:481–94. 6. Bowman SJ. Distal Jets refined: Bowman modification and Horseshoe Jet. AOAppliances. 2008;1–5. 7. Kinzinger GSM, Eren M, Diedrich PR. Treatment effects of intraoral appliances with conventional anchorage designs for non-compliance maxillary molar distalization: a literature review. Eur J Orthod. 2008;30:558–71. 8. Gianelly AA, Bednar J, Dietz VS. Bidimensional Technique: theory and practice. GAC International, 2000. 60 ! 9. Huerter GWJ. A retrospective evaluation of maxillary molar distalization with the Distal Jet appliance. Saint Louis University;1999. Masters Degree Thesis. St. Louis, MO. 10. Patel AN. Analysis of the Distal Jet Appliance for Maxillary Molar Distalization. University of Oklahoma;1999. Masters Degree Thesis. Oklahoma City, OK. 11. Chiu PP, McNamara JA Jr, Franchi LA. Comparison of two intraoral molar distalization appliances: Distal jet versus Pendulum. Am J Orthod Dentofacial Orthop. 2005;128:353–65. 12. Gutierrez VME. Treatment effects of the Distal Jet appliance with and without edgewise therapy. Saint Louis University;2001. Masters Degree Thesis. St. Louis, MO. 13. Lee S. Comparison of the Treatment Effects of Two Molar Distalization Appliances. Saint Louis University;2001. Unpublished Masters Degree Thesis. St. Louis, MO. 14. Ngantung V, Nanda RS, Bowman SJ. Posttreatment evaluation of the distal jet appliance. Am J Orthod Dentofacial Orthop. 2001;120:178–85. 15. Rushforth CDJ, Gordon PH, Aird JC. Skeletal and Dental Changes Following the Use of the Frankel Functional Regulator. J. Orthod. 1999;26:127–34. 61 ! VITA AUCTORIS Krystal M. Baumgartner was born on February 13, 1984 in Bismarck, North Dakota. She attended the University of North Dakota in Grand Forks, North Dakota for her undergraduate studies with a Biology/Pre-Dental major. She attended the University of Colorado School of Dental Medicine where she earned her D.D.S. degree in 2009. Following graduation from dental school, she moved to Nashville, Tennessee where she completed a one year General Practice Residency at Meharry Medical College. In 2010, she moved to St. Louis, Missouri to begin her graduate orthodontic education at the Center for Advanced Dental Education at Saint Louis University. Dr. Baumgartner expects to receive her Masters Degree in Dentistry (Research) from Saint Louis University in December 2012. 62