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A CEPHALOMETRIC STUDY OF ADULT MILD CLASS II NONEXTRACTION TREATMENT WITH THE INVISALIGN SYSTEM Brian M. Klein, D.M.D. 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 2013 Abstract Objective: The aim of this retrospective study was to examine the skeletal and dental effects of nonextraction Class II treatment in the adult dentition with the Invisalign system and interach elastics. Materials and Methods: Twenty-eight adult patients (18 females, 10 males, mean age at start of treatment: 35.5 years) who have undergone Class II nonextraction treatment with only Invisalign aligners and interarch elastics were identified from two private practitioners. Pre-treatment and post- treatment lateral cephalograms were hand-traced and digitized. Eight angular and seven linear measurements were taken from each cephalogram. Descriptive statistics, paired t-tests, and intra-class correlations were computed to analyze the data and determine whether there were significant changes during treatment. Results: Statistically significant (p<.05) differences were found in overall treatment change for SN-MP and U1-SN. Statistically significant (p<.01) differences were found in overall treatment change for SNB, ANB, IMPA, overjet, overbite, molar relationship, upper molar linear distance from the Y-axis, and lower molar linear distance from the Y-axis. The upper molars moved distally in every subject 1 and the lower molars moved mesially resulting in a molar correction along the functional occlusal plane. The ANB angle, SN-MP, U1-SN, IMPA, overjet and overbite all decreased throughout the course of treatment. Conclusions: The Invisalign system is a viable option for nonextraction mild Class II treatment in adults. Class II treatment with the Invisalign system is capable of providing reliable upper molar distalization and improvement in molar relationship while maintaining an element of control in the vertical dimension. Assuming compliance by the patient and an understanding of how the Invisalign software relates to clinical tooth movements, the practitioner can expect some dentoalveolar Class II correction in the adult dentition. 2 A CEPHALOMETRIC STUDY OF ADULT MILD CLASS II NONEXTRACTION TREATMENT WITH THE INVISALIGN SYSTEM Brian M. Klein, D.M.D. 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 2013 COMMITTEE IN CHARGE OF CANDIDANCY: Professor Eustaquio A. Araujo, Chairperson and Advisor Professor Rolf G. Behrents Associate Clinical Professor Donald R. Oliver i DEDICATION This work is dedicated to my wife, Jane. I thank her greatly for her constant love over the last five years and the promise of many, many more. Where most spouses would be good just to give encouragement, she shows genuine interest. My orthodontic accomplishments are made all the more enjoyable because they are shared through her understanding of the specialty. I am lucky to have such a devoted wife and I love her very much. To my parents, Christopher and Dianne, whose example is my barometer for life. Their love, sacrifice, and support have allowed me more opportunities than I deserve. I love and respect them to the highest degree. And to the faculty of Saint Louis University, who have taught me invaluable life and professional lessons. The selflessness of their approach to my education will bear benefit for the rest of my life and it is much appreciated. ii ACKNOWLEDGEMENTS I would like to thank Dr. Araujo for accepting the position as chair of my thesis committee. I very much appreciate his knowledge, time, and perpetual passion. We should all be challenged to do more for and receive more enjoyment from orthodontics, as Dr. Araujo has set the standard in both respects. Thank you Dr. Behrents for the remarkable opportunity to learn under his leadership at such a prestigious orthodontic program. His ability to extract every last drop of potential from his residents makes us better as people, as a program, and as a specialty. Thank you Dr. Oliver for his knowledge, enthusiasm, and incredible attention to detail. All are appreciated and of great benefit in both research and clinical endeavors. Thank you Dr. Sam Daher, Dr. Farhad Moshiri, Dr. Mazyar Moshiri, Dr. William Kottemann, and their respective orthodontic staffs for providing the records used in this study and a prior pilot study. Despite demanding schedules and busy practices all were thorough and kind in their assistance. iii Thank you Dr. Heidi Israel for her time and expertise in statistical analysis. Thank you Align Technology, Inc. for their interest and support in this study. In particular, Dr. Rene Sterental, Shawn Pemberton, and John Missey for their efforts in database navigation and facilitating contacts. iv TABLE OF CONTENTS List of Tables ........................................... vi List of Figures ......................................... vii CHAPTER 1: INTRODUCTION .................................. 1 CHAPTER 2: REVIEW OF THE LITERATURE Class II Malocclusion ..................................... 5 Definition .............................................. 5 Prevalence .............................................. 6 Etiology ................................................ 7 Nonextraction Treatment with Interarch Elastics ........ 10 Adult Class II Orthodontics .............................. 15 Statistics ............................................. 15 Correction ............................................. 16 Extraction Treatment ................................... 18 Functional Appliance Treatment ......................... 23 Invisalign ............................................... 26 History of Clear Removable Appliances .................. 26 Introduction of Invisalign ............................. 28 Invisalign as an Alternative Orthodontic Treatment ..... 30 Invisalign in Nonextraction Adult Class II Treatment .. 36 Statement of Thesis ...................................... 37 References ............................................... 38 CHAPTER 3: JOURNAL ARTICLE Abstract ................................................. Introduction ............................................. Materials and Methods .................................... Sample ................................................. Data Collection ........................................ X-Y Axis Coordinate System ............................. Statistical Methods .................................... Results .................................................. Cephalometric Comparison ............................... X-Y Axis Coordinate System ............................. Discussion ............................................... Skeletal A-P Changes ................................... Skeletal Vertical Changes .............................. Maxillary Dental Changes ............................... Mandibular Dental Changes ............................. Dental Relationship Changes .............................. Conclusions .............................................. References ............................................... Appendix ................................................. 46 47 50 50 52 55 58 58 58 62 64 64 65 66 67 68 69 70 73 Vita Auctoris ............................................ 85 v LIST OF TABLES Table 2.1 – Adult orthodontics practice trends ........... 16 Table 3.1 – Sample age, gender, and treatment duration ... 51 Table 3.2 – Cephalometric definitions .................... 54 Table 3.3 – Descriptive statistics of T1 and T2 .......... 60 Table 3.4 – Descriptive statistics of treatment changes .. 61 Table A.1 – Sample ages and treatment duration ........... 73 Table A.2 – Sample Angle classification statistics ...... 74 Table A.3 – Anatomical landmark definitions .............. 75 Table A.4 – Intra-class correlation values ............... 79 Table A.5 – Mean X-Y axis coordinates .................... 80 vi LIST OF FIGURES Figure 2.1 – Angle Class I and Class II malocclusions ... 6 Figure 2.2 – Example of an Invisalign aligner .......... 29 Figure 3.1 – Anatomical landmarks ...................... 53 Figure 3.2 – Horizontal X-Y axis measurements .......... 56 Figure 3.3 – Vertical X-Y axis measurements ............ 57 Figure 3.4 – Graphic overlay of treatment changes ...... 63 Figure A.1 – Cephalometric planar measurements ......... 76 Figure A.2 – Cephalometric angular measurements ........ 77 Figure A.3 – Fucntional occlusal plane measurements .... 78 Figure A.4 – Graphic overlay of T1 measurements ........ 81 Figure A.5 – Graphic overlay of T2 measurements ........ 82 Figure A.6 – Class II division I graphic overlay ....... 83 Figure A.7 – Class II division II graphic overlay ...... 84 vii Chapter I: Introduction “Orthodontic therapy is essentially a game of strategy against Nature. In this game, Nature is neither malevolent nor capricious. She plays by rules that can at least be described and against which optimal strategies can be formulated.”1 - Lysle Johnston, Jr. In orthodontics Class II malocclusion presents as a complexity in both origin and correction. Both have been studied extensively and yet, both remain a continuing challenge for each generation of practitioners. of Class II malocclusion is multifactorial. The origin The malocclusion is defined as a distal relation of the lower dentition to the upper, but the underlying causes are not simplistic. Genetics, growth, environmental effects, occlusal development, dental positions, and skeletal positions are all to be considered when evaluating a Class II patient. An appropriate diagnosis and understanding of the malocclusion is vital to responsible treatment. The correction of Class II malocclusion is multifactorial as well. A Class I molar and canine relationship is considered a successful treatment outcome, but there are numerous ways to arrive at this goal in treating Class II malocclusions. 1 Interarch elastics, extractions, distalizers, headgear, fixed functional appliances, removable functional appliances, and surgical interventions are some of the commonly used approaches to treat Class II malocclusion. Proper Class II correction also requires knowledge of potentially adverse effects inherent in the aforementioned correction methods. Upper incisor retroclination, lower incisor proclination, lower molar extrusion, and tipping of the occlusal plane can be unwanted results of certain Class II treatments. Class II diagnosis and correction are heavily dependent on whether and how much growth can be expected from the patient. The anticipated amount of differential growth by the mandible as compared to the maxilla can influence the orthodontic treatment planning process. Typically, adolescents are expected to contribute varying amounts of favorable skeletal growth, while adults are relegated to mostly dental compensations. The pervasiveness of Class II malocclusion, growing interest in orthodontics by the adult population, and demand for esthetic treatment in all age groups has created a niche for techniques capable of satisfying those prerequisites. Invisalign clear, removable aligners as a mode of orthodontic treatment have gained increasing attention 2 since their first U.S. commercial sales to orthodontists in 1999. Although limited in publication through refereed journals, studies have shown Invisalign to be a reasonable strategy for correction of minor malocclusions. Initially branded as an esthetic alternative to traditional braces for low complexity cases, patient demand and advances in technologies have led some orthodontists to broaden their use of Invisalign. Theoretical effects of the aligners such as a biteplate effect, incisor angulation control, and vertical control appeal to some practitioners. To date, no appropriate studies have been published on any of the aforementioned assertions with regard to Invisalign when used as a mode of Class II treatment. The purpose of this study is to evaluate the skeletal and dental effects of Class II nonextraction treatment in adults using the Invisalign system of treatment and interarch elastics. Pre-treatment and post-treatment cephalometric analysis will allow a description of the changes in molar relationship, overjet and overbite correction, incisor angulation, vertical dimension, and changes of the occlusal plane. Of particular importance will be how this method of Class II treatment contrasts 3 with conventional fixed appliance treatment using interarch elastics in adolescents and adults. 4 Chapter II: Review of Literature Class II Malocclusion Definition In the 1890s, Edward H. Angle developed a classification system for occlusal relationships in the natural dentition.2 The basis of the normal occlusion and subsequent malocclusions was the position of the upper first molar. In normal occlusion the mesiobuccal cusp of the upper first molar occludes with the buccal groove of the lower first molar. Normal occlusion and Class I malocclusion share the same molar relationship, but Class I malocclusion also presents with rotated or malposed teeth. Class II malocclusion, as described by Angle, is the distal relation of the lower dentition to that of the upper (Figure 2.1). This malocclusion is evident specifically by the buccal grove of the lower first molar presenting distal by at least one-half cusp to the mesiobuccal cusp of the upper first molar.2 A common goal of orthodontic treatment is to return the patient to normal occlusion whenever possible. 5 22 CHAPTER 1 The Decision-Making Process in Orthodontics Normal occlusion Class II malocclusion Class I malocclusio Class III malocclusi FIGURE 1-10 Angle suggested that in ideal occlusion the mesiobuccal cusps of the maxil rest in the buccal grooves of the mandibular first molars. He called the permanent first mo Figure 2.1. Angle Class I and Class IImolar malocclusion. Modified from that two variations of sion and designated this ideal relationship Class I. He observed th exist, and he designated these Class II and Class III. Subsequently, Graber, Orthodontics: Current Techniques and Principles 5 ed. the relationship of the can of the description of Class I, II, and III probably as a result of Simon’s influential but erroneou textbook.3 lary canines were the keys to occlusion. Nonetheless, the maxillary canines should ideally between the mandibular canines and first premolars. Prevalence into orthodontic therapy has made it necessary for this system is defined as a s orthodontists to add arch-perimeter analysis as an addiin a set have some commo tional step in classification. There are two major co In the 1970s an effort was made by the United States A final, but not inconsequential, difficulty with Angle’s scheme: (1) dentofacial ap classification procedure is that it does not indicate the tionships of the teeth and j Public Health Service (USPHS) to better gauge the nationcomplexity and severity of the problem. five or fewer major chara It is for these reasons that we advocate systematically wide health status. A massive survey was performedcondition by the is needed to ful enhancing the Angle classification by describing the five are several other factors th major characteristics of malocclusion. arriving at these five desc Division of Health Examination Statistics to examine youths listed as follows: Ackerman-Proffit agesSystematic 12 to 17. Description: Among the data collected was information 1. Dentofacial appearance • Facial symmetry/ver regarding malocclusion. It was estimated that 32% of • the To overcome the difficulties just discussed, we recomAnterior tooth displ • Orientation of the mend using a classification scheme in which five or 4 7,500 youth sample had Classinterrelationships II malocclusion. fewer characteristics anda their are NHP (natural head 63,64 • assessed. A complex of interrelated variables, as Profile consideration encountered in many orthodontic conditions, may be 2. Spatial relationships of • Arch alignment and represented most conveniently through the use of sets. • Anteroposterior cha Venn proposed this representation in 1880, and his idea 6 • Transverse character has become prominent in symbolic logic for computer • Vertical characteristi use. The set theory deals with collections or groups of • Orientation of the o entities and it represents the relationships between these groups by graphic patterns. A Venn diagram offers a visual demonstration of interaction or overlap among The five or fewer descrip Classification (the Orthogonal Analysis) A broadened national health survey was performed in 1989-1994 known as the National Health and Nutrition Estimates Survey III (NHANES III). The NHANES III used a sample of 14,000 participants to provide health information for children, youths, and adults.5 This information served as a tool that oral health professionals could reference for various data sets organized by age and ethnic groups. Class II malocclusion, described by the NHANES III as more than 4 mm of overjet, appeared in 11% of the sample and made up 20% of all malocclusions making it the most common skeletal discrepancy. Class II malocclusion was featured in 10.1% of Caucasians, 11.8% of African Americans, and 6.5% of Hispanics.5 Etiology Given that Class II malocclusion is the most common jaw discrepancy in the United States, an effort has been made by the orthodontic community to understand its origins. An assortment of skeletal and dental predispositions comprise the underlying causes and appearance of Class II malocclusion. Moyers performed a multivariate cluster analysis using cephalometric data of 610 patients to determine the facial types associated with 7 Class II malocclusion. By analyzing phenotype characteristics, he was able to define six subgroups based on horizontal components and five subgroups based on vertical components.6 The horizontal subgroups were defined as either; maxillary dental protrusive, midface protrusive, maxillary and mandibular retrognathic with dental protrusion, maxillary and mandibular retrognathic with only maxillary protrusion, maxillary prognathic with maxillary dental protrusion, or mandibular retrognathic. Vertical subgroups were based on comparisons to the Michigan Growth Study norms utilizing the position of the cranial base, palatal plane, occlusal plane, and mandibular plane. Moyers concluded that not all vertical types are found in each horizontal type, but there is a strong relationship between horizontal and vertical features. The study suggests there are 15 Class II subtypes that can be defined by pairing the horizontal and vertical subgroups. McNamara looked at lateral cephalometric radiographs of 277 children ages 8 to 10 with Class II malocclusion.7 He found mandibular skeletal retrusion to be the most common single characteristic of Class II malocclusion with the maxilla usually in a neutral skeletal position. In evaluating the dentition he found less maxillary incisor 8 proclination than previous studies and generally neutral lower incisor angulation. McNamara also found that nearly half of the sample featured an excessive vertical component, which was determined by mandibular plane angle and lower face height. In all, the study recognized 77 of the 243 possible combinations of Class II malocclusions from the skeletal, dental, and vertical components. The combination of neutral maxillary position, retrusive mandibular skeletal, and excessive vertical dimension was the most common, representing only 10% of the overall sample. In a longitudinal study, Buschang and Martins looked at childhood and adolescent growth changes in the anteroposterior and vertical dimensions.8 Lateral cephalometric radiographs of 49 females and 50 males with roughly equivalent Class I and Class II malocclusions were analyzed for childhood and adolescent growth changes respectively. Childhood growth was described as 6 to 10 years for females and 8 to 12 years for males. Adolescent growth was described as 9 to 13 years for females and 11 to 15 years for males. The distance between ANS and pogonion was used to determine the skeletal vertical relationship and distance between pogonion and gonion was used to 9 determine the skeletal anteroposterior relationship. It was found that anteroposterior discrepancies had greater potential to improve during childhood than adolescence. They attributed worsening of the anteroposterior relationship in adolescence primarily to deficiency of horizontal mandibular growth. Vertical growth changes were found to be significantly greater in adolescence than childhood. The study concluded that neither anteroposterior or vertical relationships were stable during growth.6 Nonextraction Class II Treatment with Interarch Elastics There are a number of methods available to orthodontists for correction of nonextraction Class II malocclusions, but the most common is use of interarch elastics. Widespread and long-term use of this method has allowed for thorough study of the clinical effects. In 1955, Tovstein published a study on the effects of Class II correction with elastics on the occlusal plane.9 He looked at 81 nonextraction Class II patients at time points before treatment, at the end of treatment, and at least 2 years into retention. The results showed that Class II elastics increased the SN-occlusal plane angle and decreased the ANB 10 angle. Subjects displaying the most growth during the course of treatment showed a lesser increase in the occlusal plane angle and more improvement in ANB angulation than subjects with the least growth. The study showed that tipping of the occlusal plane occurs with Class II elastic use, but severity is related to growth of the patient. Hanes later investigated skeletal profile changes of 38 Class II patients treated with interarch elastics.10 His results showed that Class II elastics moved A-point and Bpoint distally 2.5 mm and 0.9 mm respectively. Despite mesial force exerted on the mandibular dentition by the elastics, a net posterior movement of B-point was due to the mean 0.8 degrees clockwise mandibular rotation. Hanes determined that skeletal Class II correction is mostly from distally moving A-point and Class II elastics do not enhance chin projection due to clockwise mandibular rotation. Gianelly et al. did a cephalometric comparison of Class II treatment with elastics utilizing different bracket systems.11 43 cases were treated with either light wire (Begg) or edgewise appliances and evaluated for linear and angular changes. There were no statistically significant differences between the techniques. 11 Both appliances showed a decrease in SNA angle, an increase in SNB angle, and an increase in mandibular plane angle. The SNA angle was reduced slightly more and mandibular plane increased slightly less in the edgewise group. The SNB angle increased slightly more in the Begg group. Meistrell et al. performed a study on 42 nonextraction Class II cases treated with the Begg appliance and Class II elastics.12 They found a mean decrease in the ANB angle of 1.3 degrees and mandibular incisor proclination of 3.67 degrees. The occlusal plane rotated counterclockwise 0.3 degrees. Both maxillary and mandibular molars moved mesially at 0.2 mm and 1.2 mm respectively. Also, both maxillary and mandibular molars showed extrusive movement at 2.1 mm and 2.6 mm respectively. Ellen et al. looked at horizontal and vertical cephalometric changes in 56 nonextraction Class II patients treated with edgewise appliances and elastics.13 Their results showed a mean 4.0 mm mesial and 4.1 mm extrusive movement of the mandibular first molars. The maxillary incisors extruded 3.7 mm and retroclined 1.4 degrees, while the mandibular incisors proclined 1.4 degrees. The occlusal plane displayed a clockwise rotation of 0.8 12 degrees. SNA and ANB angles decreased significantly with only minimal decrease in the SNB angle. Nelson et al. performed a two-part study on nonextraction Class II correction with interarch elastics. The first study was prospective and looked at 18 Class II patients treated with the Begg technique.14 The results showed a 3.7 mm distal movement of the maxillary incisors and a 1.0 mm mesial movement of the mandibular incisors. Maxillary molar movement was insignificant, while there was 2.0 mm mesial movement of the mandibular molars. mandibular plane angle increased 1.0 degree. The Mean overjet reduction was 5.8 mm and mean molar correction was 3.0 mm. The second study utilized a different sample involving 18 nonextraction Class II patients treated with Begg appliances and elastics.15 The authors found a 5.1 mm distal movement of the maxillary incisors and 1.4 mm mesial movement of the mandibular incisors. The maxillary and mandibular molars both moved mesially with 1.3 mm and 1.6 mm of movement respectively. The mean mandibular plane angle increased 1.3 degrees. Mean overjet reduction was 6.7 mm and mean molar correction was 3.1 mm. Combrink et al. looked at dentoskeletal changes in 35 Class II patients treated nonextraction with Class II 13 elastics.16 Results from the study showed a mean decrease in the SNA and ANB angles with 1.6 degrees and 1.7 degrees respectively. The inter-incisal angle decreased 21.8 degrees and overjet correction was measured at 3.8 mm. An evaluation of the soft tissue profile showed slightly more lower lip advancement than compared to the upper, which improved the profile and lip relationship. Jones et al. compared nonextraction Class II patients treated with either the Forsus appliance or elastics.17 Thirty-four growing patients were treated with each Class II correction method and evaluated for post-treatment changes. Both groups showed mesial movement of the maxilla, mandible, and dentition. The group treated with elastics featured 3.8 degrees of mandibular incisor proclination, 3.2 mm of mandibular molar extrusion, and clockwise occlusal plane rotation of 1.0 degree. Overjet correction was measured as 2.8 mm and molar correction was 2.4 mm. The authors concluded that both Forsus and interarch elastics were capable of efficiently correcting Class II malocclusion. Janson et al. recently performed a systematic review of the orthodontic literature relating to Class II treatment with elastics.18 Eleven articles satisfied the 14 inclusion criteria from a search of multiple databases on the topic. The authors concluded that Class II elastics are an effective method for treatment of Class II malocclusion and correction is mostly dentoalveolar in nature. Component dentoalveolar effects of Class II elastics were retraction and extrusion of the maxillary incisors, proclination of the mandibular incisors, and mesial and extrusive movements of the mandibular first molars. Adult Class II Orthodontics Statistics The ability to effectively treat the varying malocclusions of the adult patient is a necessary tool in modern orthodontics. The 2011 Journal of Clinical Orthodontics (JCO) practice study on trends throughout the specialty revealed that adult patients comprise 20% of all case starts and command a consistently higher treatment fee than adolescent cases (Table 2.2).19 Multiple studies, both American and international, have found the incidence of adult malocclusion to be as high as 70%.5,20-23 Data from the NHANES III indicated that of the adult population, defined 15 as people ages 18 to 50, 57% presented with inadequate overjet and 50% with inadequate overbite.5 A 2012 retrospective study by Cedro et al. of nonsurgical adult patients identified the mean age of adult patients as 31.2 years of age. The patients were predominantly female at 76.2% of the sample with Class II division I malocclusion being the most commonly presenting malocclusion.24 Practice Activity (Medians) 1981 1989 1997 2003 2009 2011 150 150 180 212 220 200 15.4% 22.3% 19.1% 18.8% 20.0% 20.0% 300 350 400 500 495 450 15.2% 20.0% 15.4% 16.7% 18.0% 17.8% Child Fee $1,900 $2,800 $3,600 $4,390 $5,150 $5,200 Adult Fee $2,100 $3,000 $3,900 $4,800 $5,500 $5,550 Case Starts Adult Case Starts Active Treatment Cases Adult Active Cases Table 2.1. Adult orthodontics practice trends. Modified from 2011 JCO Orthodontic Practice Study, Part 1: Trends.19 Correction Knowledge of the contributing factors to Class II malocclusion helps in determining the appropriate treatment. Identifying the component or components of the malocclusion can dictate the most effective method of correcting the jaw discrepancy. Differential skeletal growth of the craniofacial structures is evident in how 16 mandibular growth outpaces that of the maxilla during development. Since we understand Class II malocclusion as a distal positioning of the mandible in relation to the maxilla, a common misconception is that natural growth could be self-correcting in adolescent patients. However, Proffit describes differential growth as only capable of providing 3-4 mm towards Class II correction.25 Orthodontists faced with treating Class II malocclusion of adult patients lose the advantage of differential jaw growth, regardless of the increment. Furthermore, multiple growth studies on untreated Class II samples show that growth in the vertical dimension actually creates more convexity, exacerbating the Class II facial pattern.26-28 Without the benefit of horizontal growth and the potential hindrance of continued vertical growth there are fewer options in treating adult Class II malocclusions. Methods for addressing this condition are primarily isolated to orthodontic camouflage and orthognathic surgery. Orthodontic camouflage is an attempt at correction of the overjet via extraction of upper first premolars while leaving the posterior in Class II occlusion or extraction of upper and lower premolars. 17 This approach relies almost entirely on dental movement and does little to address the underlying skeletal discrepancy. Fixed functional appliances are a common approach for Class II correction in the growing patient, but some practitioners see a niche for them in adult patients as well. This technique is aimed at producing remodeling of the temporomandibular joint for some skeletal improvement, but mostly dental reaction to the force system.29,30 Orthognathic surgery for Class II correction features proper alignment of the intra-arch dentition with orthodontics followed by a mandibular advancement osteotomy. This is a combined technique that addresses both the dental and skeletal aspect of the malocclusion. As this study is investigating nonsurgical Class II correction, it is only appropriate to review literature concerning adults treated with orthodontic camouflage or fixed functional appliances. Extraction Treatment In 1991, Harris et al. looked at the dental and skeletal effects of Class II treatment in adolescents and adults with Tweed edgewise mechanics.31 18 The sample consisted of 30 adolescent girls with a mean age of 12.5 years and 26 adult females with a mean age of 27.6 years. The entire sample displayed a Class II division I malocclusion and were treated with extraction of four premolars. Cephalometric analysis showed a 1.2 mm distal tipping of the maxillary molars in the adult sample with a 2.5 mm mesial translation of the maxillary molars, due to growth in the adolescent sample. Relative to the maxilla, the adult mandibular molars moved forward less than half that of the adolescents by 2.8 mm and 6.1 mm respectively. The maxillary incisal edge of both samples was retracted significantly in both samples. The adolescent mean functional occlusal plane rotated by counterclockwise 0.96 degrees and rotated clockwise 4.44 degrees in the adult sample. This steepening of the occlusal plane in the adult reduced maxillary and mandibular molar movements relative to the plane. In 1992, Proffit et al. compared the outcomes of orthodontic versus surgical intervention in adult Class II malocclusions.32 Thirty-three patients treated orthodontically with extractions were evaluated. A point moved distally 0.9 mm, B point moved distally 0.8 mm, the ANB angle decreased 0.4 degrees, and the mandibular plane 19 angle increased 0.3 degrees. Overjet was reduced by 2.9 mm and overbite was reduced by 1.1 mm. The authors matched the post-treatment measurements with an acceptable range and an ideal value to determine the percentage goal achieved. While both orthodontic and surgical treatments scored most values in the acceptable range, the surgical method of treatment score significantly better in achieving an ideal value. In 1993, Cassidy et al. analyzed Class II treatment in adults deemed “borderline” between orthodontic and surgical correction.33 The orthodontic sample consisted of 27 adults treated with either nonextraction or a variety of extraction protocols. Cephalometric analysis showed a 2.7 mm reduction in overjet, 0.3 mm increase in overbite and 0.1 mm improvement in molar relationship. SNA reduced 0.4 degrees, SNB reduced 0.5 degrees, and ANB increased 0.1 degrees. SN-GoGn increased 0.5 degrees and the SN- functional occlusal plane increased 2.4 degrees. After thorough analysis of both samples, the authors determined that orthodontic treatment for adult Class II “borderline” patients would be the better choice. In 1995, Vaden et al. compared Class II correction in adolescent and adult patients.34 20 The adolescent sample consisted of 22 patients who were 15.1 years at posttreatment and the adult sample consisted of 23 patients who were 31.9 years at post-treatment. All patients were female, had four premolars extracted, and were treated with Tweed edgewise mechanics. In the adolescent sample, SNA moved distally 1.75 degrees and SNB moved distally 0.10 degrees. The maxillary incisor retracted 5.91 mm and the mandibular incisor protracted 1.49 mm. The maxillary molars moved mesially 2.47 mm and extruded 1.89 mm, while the mandibular molars moved mesially 3.87 mm and extruded 3.11 mm. Change in the mandibular plane angle was negligible, the functional occlusal plane to Frankfort horizontal reduced 0.46 degrees, and the IMPA reduced 0.59 degrees. In the adult sample, SNA moved distal 1.22 degrees and SNB moved distally 0.48 degrees. The maxillary incisor retracted 7.47 mm and the mandibular incisor protracted 0.51 mm. The maxillary molars moved distally 0.08 mm and intruded 0.98 mm, while the mandibular molars moved mesially 2.49 mm and extruded 2.43 mm. The mandibular plane angle increased 0.57 degrees, the functional occlusal plane to Frankfort horizontal increased 4.42 degrees and the IMPA reduced by 0.47 degrees. 21 The authors concluded that there are major differences between Class II treatment of both age groups, but a lack of growth doesn’t exclude the adult patient from correction of the malocclusion. In 2009, Liu et al. evaluated the skeletal and dental effects of nonextraction Class II treatment in postpeak growth stage patients with Multiloop Edgewise (MEAW) mechanics and Class II elastics.35 Cephalometric analysis was performed on 16 patients, 11 females and 7 males, with a mean age of 15.9. A point moved mesially 0.7 mm and B point moved mesially 1.6 mm. The maxillary incisors retracted 1.7 mm the mandibular incisors protracted 1.9 mm. The maxillary molars moved mesially 0.5 mm and extruded 0.4 mm, while the mandibular molars moved mesially 1.4 mm and extruded 1.2 mm. SN-PP and SN-GoGn angles reduced 0.8 degrees and 0.4 degrees respectively. Given the postpeak growth status of the sample, the authors credited skeletal change with 30% of the incisal changes and 54% of molar changes. 22 Functional Appliance Treatment In 1999, Ruf and Pancherz performed a prospective study on dental and skeletal changes in adult Class II treatment with the Herbst fixed functional appliance.36 Fourteen young adults with a mean pre-treatment age of 16.5 years were evaluated immediately before and after Herbst wear. Dental component evaluation showed a 3.6 mm retraction of the maxillary incisors and 3.8 mm proclination of the mandibular incisors. The maxillary molars were measured at 2.7 mm of distal movement and the mandibular molars 3.8 mm of mesial movement. Further analysis of the data claimed a 22% skeletal correction concerning the overjet and 78% dental. Molar correction was portrayed as 25% skeletal and 75% dental. Ruf and Pancherz later presented a study comparing surgical adult Class II correction with Herbst Class II treatment.37 Twenty-three patients who received a mandibular sagittal split osteotomy and 23 patients treated with the Herbst appliance were evaluated for pre-treatment and post-treatment skeletal and dental changes. For the Herbst group, results showed a mean decrease in overjet of 6.7 mm with the maxillary incisors retruding 3.2 mm and mandibular incisors proclining 2.7 mm. 23 The maxillary molars moved distally 1.8 mm and mandibular molars moved mesially 1.4 mm. The Herbst group showed more overjet correction, more maxillary incisor retroclination, more mandibular incisor proclination, less molar correction, an increased facial height, and less profile correction when compared to the surgical group. The dental components of overjet and molar correction for the Herbst group were found to be 87% and 78% respectively. Kinzinger et al. performed a cohort study measuring the effects of adult Class II treatment with orthodontic camouflage, dentofacial orthopedics, and orthognathic surgery.38 Sixty young adults, 20 for each treatment method, were evaluated for linear and angular changes in pre-treatment and post-treatment cephalograms. The orthopedic group, which was represented by Herbst appliance treatment, had a mean pre-treatment age of 18.7 years. This group showed no significant changes skeletal changes for either the maxilla or mandible. The maxillary incisors were retracted 2.35 mm and retroclined 3.9 degrees, while the mandibular incisors moved mesially 2.46 mm and were proclined 7.27 degrees. The total overjet correction was largest in the functional appliance group with 4.9 mm and the overbite decreased by 0.7 mm. 24 The maxillary molars moved distally 1.88 mm and the mandibular molars moved mesially 0.77 mm. The SN-MP decreased 0.38 degrees and SN- PP decreased 0.66 degrees. In the extraction group there were no statistically significant movements of the maxilla or mandible. The maxillary incisors retracted 4.96 mm and retroclined 6.36 degrees, while the mandibular incisors retracted 4.07 mm and retroclined 4.16 degrees. Total overjet correction was 0.97 mm and the overbite increased 0.56 degrees. The maxillary molars moved mesially 0.45 mm and the mandibular molars moved mesially 1.51 mm. The SN-MP increased 1.25 degrees and SN-PP increased 0.49 degrees. Despite some bony chin projection and reduction in the soft tissue profile convexity for the functional appliance group, only the orthognathic surgery group produced significant treatment-related changes. A 2012 prospective clinical study by Upadhyay et al. compared Class II correction in young adult females treated with either temporary anchorage device assisted (TAD) upper first premolar extractions or fixed functional appliances.39 Eighteen female patients with a mean age of 16.5 years underwent nonextraction Class II treatment with the Forsus appliance. This group showed a reduction in the ANB angle 25 of 1.5 degree through a decrease in SNA angle of 0.6 degree and increase in SNB angle of 1.0 degree. The maxillary incisors retroclined 7.3 degrees and the mandibular incisors proclined 10.7 degrees. The SN-MP angle decreased 0.3 degree, while the SN-occlusal plane angle increased 0.7 degree. The authors noted that both the extraction and functional appliance groups both provided adequate dental compensation to correct the Class II malocclusion, but did not affect the skeletal discrepancy. The authors also noted that fewer side effects were noted in the functional appliance group resulting in less time required for finishing and an overall shorter treatment time. Invisalign History of Clear Removable Appliances Kesling is credited with the introduction of removable aligners through use of positioning trays in 1945. These one-piece pliable rubber mouth guards, or “tooth positioners,” were made from idealized lab set-ups and used as a finishing technique to close residual spaces after debanding.40 Kesling’s technique was promising in that it could serve in both minor correction and retention. 26 However, material limitations of the era and extensive lab preparation prevented a broadened use of the appliances. Ponitz and later McNamara et al. employed the same general lab arrangements previously described by Kesling, but utilized thermoformed plastic for the aligner material.41,42 In 1993, Sheridan et al. introduced thermoplastic copolyester trays primarily as a mode of retention, but also minor tooth movement. Advantages attributed to the aligners were durability, ease of cleaning, ease of fabrication, low cost of fabrication, and esthetics.43 The idea was to perform interproximal reduction and apply sequential retainers that could result in minimal range tooth movements. Eventually, thermoforming pliers were added to the armamentarium to facilitate control of aligner movements at chairside.44 Again, lab preparation often outweighed the benefits of minor tooth movements as new impressions and model set-ups were required at each appointment. In 1997, Rinchuse and Rinchuse presented a set of case reports showing minor malocclusion correction with Essix trays in conjuction with bonded attachments, finger springs, or palatal expanders.45 Vacuum-formed Essix retainers, originally coined Sheridan’s Simple System of 27 Stabilizing the Social Six, remain a staple of orthodontic retention.46 Introduction of Invisalign Founded in 1997 by Stanford University business students Kelsey Wirth and Zia Chishti, Align Technology Inc. (Align Technology, Santa Clara, Calif) became the first company to mass-produce aligners for the treatment of malocclusion with the introduction of Invisalign.3 Invisalign aligners are generated by computer-aided design/computer-aided manufacturing (CAD/CAM) technology from either polyvinylsiloxane or digital impressions. Impressions are scanned or imported into the Align system to create a detailed digital study model. From this model, Align technicians generate a virtual correction of the malocclusion through the ClinCheck software. The clinician can then use the software to manipulate the process or outcome by describing revisions to Align. When the clinician has given final approval the lab will use a movement algorithm to generate sequenced stages of orthodontic correction. An acrylic model of each stage is produced by stereolithography, which is a method of making solid objects by printing successive thin layers of 28 photocurable material on top of one another.47 Finally, 0.75 mm trays are made for each model and designated for shipping. Each Invisalign aligner (Figure 2.3) is predetermined for 0.25 mm to 0.33 mm of tooth movement and is to be replaced in sequence every two weeks.48,49 Align received FDA approval in 1998, began its first commercial sales of Invisalign to U.S. orthodontists in 1999, and spread to European markets in 2001. Currently, the Invisalign system is offered in 45 countries and has been used to treat more than 1.5 million patients.50 Figure 2.2. Example of an Invisalign aligner.50 29 Invisalign as an Alternative Orthodontic Treatment Practitioners are charged with determining whether patients seeking a superior esthetic alternative to braces can be properly treated in that fashion. As the popularity of Invisalign has increased, so has the scope of cases deemed treatable with the removable aligner system. The first university study concerning Invisalign was performed by Boyd et al. in 2000. The results suggested that Invisalign treatment was acceptable for nonextraction adult dentition cases with mild to moderate crowding, mild to moderate spacing, nonskeletal constricted arches, and relapse.51 Since then a myriad of case report studies have featured Invisalign in correction of malocclusions far beyond the initial complexity parameters such as: extensive restorative, open bite, deep bite, Class II, Class III, extraction, and surgical cases.52-64 Aside from select case reports, editorials, and material studies, relatively few clinical studies have been published by peer-reviewed journals on Invisalign biomechanical efficiency or overall treatment outcomes. In 2005, Lagravere and Flores-Mir conducted a systematic review on the treatment effects of Invisalign aligners.65 multiple database search for “Invisalign” retrieved 22 30 A articles and only 2 of those articles met their inclusion criteria of a human clinical trial concerning treatment effects. Furthermore, the authors determined the 2 remaining articles yielded only a low level of evidence due to inadequate evaluation of the treatment effects and various methodological problems. Still, genuine efforts have been made to better understand and critique the Invisalign system. A three- part study out of the University of Washington looked at activation time and material stiffness of Invisalign aligners. The first study by Bollen et al. looked specifically at the ability of Invisalign to effectively finish prescribed orthodontic treatments.66 Fifty-one patients, based on their pre-treatment peer assessment rating (PAR) and need for extractions, were assigned to different Invisalign treatment specifications. The treatment variations were using either hard or soft plastic for the aligners and either 1-week or 2-week activation time per aligner. Patients were evaluated after completion of the initial series of aligners. The authors found no significant difference in the completion rate for hard versus soft plastic appliances. It was found that changing the aligners every 2 weeks resulted in a higher completion 31 rate than changing every week (37% vs 21%). Patients with PAR scores less than 15 and no extractions showed the highest completion rate, while those with 2 or more premolars extracted showed the lowest completion rate (46% vs 0%). The study suggests that minimal complexity, nonextraction cases using a 2-week activation protocol are more likely to treat to completion. The second study in the series by Clements et al. looked at Invisalign correction evaluated by individual dental components of the PAR.67 The same 51 patients from the first study were stratified by PAR score and need for extractions. The patients were again grouped into soft or hard plastic appliances and 1-week or 2-week activation treatment regimens. The authors found the 2-week activation protocol to have a greater percentage reduction on the PAR score and more extraction space closure. Invisalign was successful at correcting anterior alignment, moderately successful at correcting midline and overjet, and least successful at correcting buccal occlusion. Incisor extraction sites showed a significantly greater percentage of space closure than premolar extraction sites. The third study in the series by Baldwin et al. looked at space closure and adjacent tooth movements in premolar 32 extraction cases treated with Invisalign.68 Twenty-four Invisalign patients featuring at least one premolar extraction site were evaluated at pre-treatment, end of aligner sequence, and end of fixed appliances. Results of the study showed that teeth adjacent to the premolar extraction sites displayed significant tipping at the end of aligner treatment. Subsequent measurements made after placement of fixed appliances showed significant uprighting of the same teeth. The authors concluded that Invisalign premolar extraction space closure could result in significant, but correctable dental tipping. Also of note in the study was the mean treatment time of 40 months due to waiting for the aligner sequence to finish and then utilizing fixed appliance mechanics. Kravitz et al. performed a prospective clinical study to compare planned virtual tooth movements with the clinical results using Invisalign software and aligners.69 Four hundred one anterior teeth were measured from 37 Invisalign patients, 198 maxillary and 203 mandibular. Virtual models of predicted tooth position were superimposed over virtual models created from the posttreatment impressions and analyzed with Invisalign’s superimposition software. Expansion, constriction, 33 intrusion, extrusion, mesiodistal tip, and labiolingual tip movements were evaluated. The authors found that the average accuracy of Invisalign tooth movement was 41% with lingual constriction being the most accurate and extrusion the least accurate. Extrusion of maxillary incisors was the single least accurate movement studied with 18.3% accuracy. The study showed lingual crown movements was more accurate than labial movements and there was no statistical difference in accuracy for like movements between the maxillary and mandibular dentition. Djeu et al. performed a retrospective comparative cohort study looking at treatment results of 48 Invisalign cases and 48 conventional fixed appliance cases.70 The American Board of Orthodontics (ABO) discrepancy index was used to control for initial severity of malocclusion and the objective grading system (OGS) was used to evaluate final records. The authors found that the Invisalign group lost 13 points more on average than the fixed appliance group and had a 27% lower passing rate. Invisalign scores were lower than fixed appliances in the categories of buccolingual inclination, occlusal contacts, occlusal relationships, and overjet. Findings showed that Invisalign cases finished 4 months quicker on average than 34 the fixed appliance cases. Vincent did a similar study scoring 65 pre-treatment and post-treatmentt Invisalign cases with the ABO OGS.71 He found significant improvements in alignment, buccolingual inclination, and interproximal spaces. Conversely, his results showed that Invisalign treatment had a negative impact on posterior occlusal contacts. Kuncio et al. used the ABO OGS to evaluate retention outcomes in Invisalign and conventional fixed appliance treatment.72 Eleven cases were recovered from Djeu’s previous Invisalign sample and matched with 11 nonextraction tip-edge fixed appliance cases for treatment length and retention length. The authors found significant changes in total alignment and mandibular anterior alignment of both groups. The Invisalign group displayed significantly more total misalignment and maxillary anterior alignment than the fixed group. Although the Invisalign group actually showed a better OGS score at debond, the overall score and alignment score worsened in retention. The fixed group improved in overall OGS score in retention, while only getting worse in the alignment category. 35 Invisalign in Nonextraction Adult Class II Treatment In 2012, Daher presented a study at the Invisalign Summit of consecutively finished Invisalign adult Class II cases and evaluated the skeletal and dental effects.73 The patients were treated with his customized sequential distalization method of Class II Invisalign treatment.74 The method is based on distal movement of the maxillary second molars by pitting them against the anchorage of the 12 anterior teeth. Class II elastics are then used to reinforce anchorage and sequentially move the buccal segments into a Class I relationship. The study sample consisted of 14 consecutively treated Class II patients with a mean age of 32 years and average treatment time of 19.3 months. Eleven patients were end-on Class II and three were full-step molar relationship. Six patients were Class II division 1 and eight were Class II division 2. Every patient showed distal movement of the maxillary molars with the mean being 1.1 mm and change in molar relation toward Class I had a mean of 1.3 mm. The lower incisors moved mesially, while holding a consistent IMPA. 36 Statement of Thesis The purpose of this study is to describe the skeletal and dental effects of nonextraction Class II treatment in adult dentition with the Invisalign system. These effects will be compared to nonextraction Class II treatment with elastics and conventional fixed appliances in adolescents and nonsurgical Class II treatments in adults. To date, the orthodontic literature does not feature any university studies on Class II treatment with Invisalign or any thorough cephalometric evaluations of the skeletal and dental effects of Invisalign treatment. It is the responsibility of our profession as a whole to investigate new appliances and techniques. Given the high demand for esthetic orthodontic treatment and the incidence of Class II malocclusion, data from this study will help practitioners make a more informed decision when considering suitable treatments for their patients. 37 References 1. Johnston LE, Jr. A comparative analysis of Class II treatment. In: Carlson DS, ed. Science and clinical judgement in Orthodontics.: Ann Arbor: Center for Human Growth and Development, University of Michigan; 1986. 2. Angle E. Treatment of Malocclusion of the Teeth and Fractures of the Maxillae. 6th ed. Philadelphia, PA: S.S. White Dent. Mfg. Co; 1900. 3. Graber L, Vanarsdall R, Vig K. 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St. Louis, MO: Mosby Elsevier; 2007. 26. Harris EF, Behrents RG. The intrinsic stability of Class I molar relationship: a longitudinal study of untreated cases. Am J Orthod Dentofacial Orthop. 1988;94:63-67. 27. Bishara SE, Jakobsen JR, Vorhies B, Bayati P. Changes in dentofacial structures in untreated Class II division 1 and normal subjects: a longitudinal study. Angle Orthod. 1997;67:55-66. 28. Phelan T, Buschang PH, Behrents RG, Wintergerst AM, Ceen RF, Hernandez A. Variation in Class II malocclusion: comparison of Mexican mestizos and American whites. Am J Orthod Dentofacial Orthop. 2004;125:418-425. 29. Ruf S, Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: A prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation. Am J Orthod Dentofacial Orthop. 1999;115:607-618. 40 30. Ruf S, Pancherz H. Temporomandibular joint growth adaptation in Herbst treatment: a prospective magnetic resonance imaging and cephalometric roentgenographic study. Eur J Orthod. 1998;20:375-388. 31. Harris EF, Dyer GS, Vaden JL. Age effects on orthodontic treatment: skeletodental assessments from the Johnston analysis. Am J Orthod Dentofacial Orthop. 1991;100:531-536. 32. Proffit WR, Phillips C, Douvartzidis N. A comparison of outcomes of orthodontic and surgical-orthodontic treatment of Class II malocclusion in adults. Am J Orthod Dentofacial Orthop. 1992;101:556-565. 33. Cassidy DW, Jr., Herbosa EG, Rotskoff KS, Johnston LE, Jr. A comparison of surgery and orthodontics in "borderline" adults with Class II, division 1 malocclusions. Am J Orthod Dentofacial Orthop. 1993;104:455-470. 34. Vaden JL, Harris EF, Behrents RG. Adult versus adolescent Class II correction: a comparison. Am J Orthod Dentofacial Orthop. 1995;107:651-661. 35. Liu J, Zou L, Zhao ZH, Welburn N, Yang P, Tang T, et al. Successful treatment of postpeak stage patients with class II division 1 malocclusion using nonextraction and multiloop edgewise archwire therapy: a report on 16 cases. Int J Oral Sci. 2009;1:207-216. 36. Ruf S, Pancherz H. Dentoskeletal effects and facial profile changes in young adults treated with the Herbst appliance. Angle Orthod. 1999;69:239-246. 37. Ruf S, Pancherz H. Orthognathic surgery and dentofacial orthopedics in adult Class II Division 1 treatment: mandibular sagittal split osteotomy versus Herbst appliance. Am J Orthod Dentofacial Orthop. 2004;126:140-152. 38. Kinzinger G, Frye L, Diedrich P. Class II treatment in adults: comparing camouflage orthodontics, dentofacial orthopedics and orthognathic surgery--a cephalometric study to evaluate various therapeutic effects. J Orofac Orthop. 2009;70:63-91. 41 39. Upadhyay M, Yadav S, Nagaraj K, Uribe F, Nanda R. Miniimplants vs fixed functional appliances for treatment of young adult Class II female patients: a prospective clinical trial. Angle Orthod. 2012;82:294-303. 40. Kesling P. The philosophy of the tooth positioning appliance. Am J Orthod. 1945;31:297-304. 41. Pontiz R. Invisible Retainers. Am J Orthod 1971;59:266272. 42. McNamara JA, Kramer KL, Juenker JP. Invisible retainers. J Clin Orthod. 1985;19:570-578. 43. Sheridan JJ, LeDoux W, McMinn R. Essix retainers: fabrication and supervision for permanent retention. J Clin Orthod. 1993;27:37-45. 44. Hilliard K, Sheridan JJ. Adjusting Essix appliance at chairside. J Clin Orthod. 2000;34:236-238. 45. Rinchuse DJ, Rinchuse DJ. Active tooth movement with Essix-based appliances. J Clin Orthod. 1997;31:109112. 46. Chudasama D. JCO Interviews: John J. Sheridan. J Clin Orthod. 2008;42:381-388. 47. Kuo E, Miller RJ. Automated custom-manufacturing technology in orthodontics. Am J Orthod Dentofacial Orthop. 2003;123:578-581. 48. Wong BH. Invisalign A to Z. Am J Orthod Dentofacial Orthop. 2002;121:540-541. 49. Align Technology, Inc. The Invisalign Reference Guide; 2012. Santa Clara, CA. 50. Align Technology, Inc. Invisalign website: Align Technology, Inc.; 2013. Available from: www.aligntech.com. 51. Boyd R, Miller RJ, Vlaskalic V. The Invisalign system in adult orthodontics: mild crowding and space closure cases. J Clin Orthod. 2000;34:203-212. 42 52. Fischer K. Invisalign treatment of dental Class II malocclusions without auxiliaries. J Clin Orthod. 2010;44:665-672. 53. Marcuzzi E, Galassini G, Procopio O, Castaldo A, Contardo L. Surgical-Invisalign treatment of a patient with Class III malocclusion and multiple missing teeth. J Clin Orthod. 2010;44:377-384. 54. Giancotti A, Farina A. Treatment of collapsed arches using the invisalign system. J Clin Orthod. 2010;44:416-425. 55. Schupp W, Haubrich J, Neumann I. Class II correction with the Invisalign system. J Clin Orthod. 2010;44:2835. 56. Schupp W, Haubrich J, Neumann I. Treatment of anterior open bite with the Invisalign system. J Clin Orthod. 2010;44:501-507. 57. Giancotti A, Mampieri G, Greco M. Correction of deep bite in adults using the Invisalign system. J Clin Orthod. 2008;42:719-726. 58. Giancotti A, Ronchin M. Pre-restorative treatment with the Invisalign system. J Clin Orthod. 2006;40:679-682. 59. Eckhart JE. Sequential MARA-Invisalign treatment. J Clin Orthod. 2009;43:439-448. 60. Womack WR, Day RH. Surgical-orthodontic treatment using the Invisalign system. J Clin Orthod. 2008;42:237-245. 61. Turatti G, Womack R, Bracco P. Incisor intrusion with Invisalign treatment of an adult periodontal patient. J Clin Orthod. 2006;40:171-174. 62. Womack WR. Four-premolar extraction treatment with Invisalign. J Clin Orthod. 2006;40:493-500. 63. Boyd RL. Surgical-orthodontic treatment of two skeletal Class III patients with Invisalign and fixed appliances. J Clin Orthod. 2005;39:245-258. 43 64. Miller RJ, Duong TT, Derakhshan M. Lower incisor extraction treatment with the Invisalign system. J Clin Orthod. 2002;36:95-102. 65. Lagravere MO, Flores-Mir C. The treatment effects of Invisalign orthodontic aligners: a systematic review. J Am Dent Assoc. 2005;136:1724-1729. 66. Bollen AM, Huang G, King G, Hujoel P, Ma T. Activation time and material stiffness of sequential removable orthodontic appliances. Part 1: Ability to complete treatment. Am J Orthod Dentofacial Orthop. 2003;124:496-501. 67. Clements KM, Bollen AM, Huang G, King G, Hujoel P, Ma T. Activation time and material stiffness of sequential removable orthodontic appliances. Part 2: Dental improvements. Am J Orthod Dentofacial Orthop. 2003;124:502-508. 68. Baldwin DK, King G, Ramsay DS, Huang G, Bollen AM. Activation time and material stiffness of sequential removable orthodontic appliances. Part 3: premolar extraction patients. Am J Orthod Dentofacial Orthop. 2008;133:837-845. 69. Kravitz ND, Kusnoto B, BeGole E, Obrez A, Agran B. How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign. Am J Orthod Dentofacial Orthop. 2009;135:27-35. 70. Djeu G, Shelton C, Maganzini A. Outcome assessment of Invisalign and traditional orthodontic treatment compared with the American Board of Orthodontics objective grading system. Am J Orthod Dentofacial Orthop. 2005;128:292-298; discussion 298. 71. Vincent S. Evaluation of Invisalign treatment utilizing the American Board of Orthodontics Objective Grading System for dental casts. Am J Orthod Dentofacial Orthop. 2005;127:268-269. 44 72. Kuncio D, Maganzini A, Shelton C, Freeman K. Invisalign and traditional orthodontic treatment postretention outcomes compared using the American Board of Orthodontics objective grading system. Angle Orthod. 2007;77:864-869. 73. Daher S, editor Invisalign treatment for Class II correction. 2012 Invisalign Summit; 2012; Las Vegas, NV. 74. Align Technology, Inc. Dr. Sam Daher's techniques for Class II correction with Invisalign and elastics: Align Technology, Inc.; 2011 [cited 2013 July 1, 2013]. 45 CHAPTER 3: JOURNAL ARTICLE Abstract Objective: The aim of this retrospective study was to examine the skeletal and dental effects of nonextraction Class II treatment in the adult dentition with the Invisalign system and interach elastics. Materials and Methods: Twenty-eight adult patients (18 females, 10 males, mean age at start of treatment: 35.5 years) who have undergone Class II nonextraction treatment with only Invisalign aligners and interarch elastics were identified from two private practitioners. Pre-treatment and post- treatment lateral cephalograms were hand-traced and digitized. Eight angular and seven linear measurements were taken from each cephalogram. Descriptive statistics, paired t-tests, and intra-class correlations were computed to analyze the data and determine whether there were significant changes during treatment. Results: Statistically significant (p<.05) differences were found in overall treatment change for SN-MP and U1-SN. Statistically significant (p<.01) differences were found in overall treatment change for SNB, ANB, IMPA, overjet, overbite, molar relationship, upper molar linear distance from the Y-axis, and lower molar linear distance from the Y-axis. The upper molars moved distally in every subject 46 and the lower molars moved mesially resulting in a molar correction along the functional occlusal plane. The ANB angle, SN-MP, U1-SN, IMPA, overjet and overbite all decreased throughout the course of treatment. Conclusions: The Invisalign system is a viable option for nonextraction mild Class II treatment in adults. Class II treatment with the Invisalign system is capable of providing reliable upper molar distalization and improvement in molar relationship while maintaining an element of control in the vertical dimension. Assuming compliance by the patient and an understanding of how the Invisalign software relates to clinical tooth movements, the practitioner can expect some dentoalveolar Class II correction in the adult dentition. Introduction In orthodontics Class II malocclusion presents as a complexity in both origin and correction. Both have been studied extensively and yet, both remain a continuing challenge for each generation of practitioners. of Class II malocclusion is multifactorial. The origin The malocclusion is defined as a distal relation of the lower dentition to the upper, but the underlying causes are not simplistic. Genetics, growth, environmental effects, occlusal development, dental positions, and skeletal 47 positions are all to be considered when evaluating a Class II patient. An appropriate diagnosis and understanding of the malocclusion is vital to responsible treatment. The correction of Class II malocclusion is multifactorial as well. A Class I molar and canine relationship is considered a successful treatment outcome, but there are numerous ways to arrive at this goal in treating Class II malocclusions. Interarch elastics, extractions, distalizers, headgear, fixed functional appliances, removable functional appliances, and surgical interventions are some of the commonly used approaches to treat Class II malocclusion. Proper Class II correction also requires knowledge of potentially adverse effects inherent in the aforementioned correction methods. Upper incisor retroclination, lower incisor proclination, lower molar extrusion, and tipping of the occlusal plane can be unwanted results of certain Class II treatments. Class II diagnosis and correction are heavily dependent on whether and how much growth can be expected from the patient. The anticipated amount of differential growth by the mandible as compared to the maxilla can influence the orthodontic treatment planning process. Typically, adolescents are expected to contribute varying 48 amounts of favorable skeletal growth, while adults are relegated to mostly dental compensations. The pervasiveness of Class II malocclusion, growing interest in orthodontics by the adult population, and demand for esthetic treatment in all age groups has created a niche for techniques capable of satisfying those prerequisites. Invisalign clear, removable aligners as a mode of orthodontic treatment have gained increasing attention since their first U.S. commercial sales to orthodontists in 1999. Although limited in publication through refereed journals, studies have shown Invisalign to be a reasonable strategy for correction of minor malocclusions. Initially branded as an esthetic alternative to traditional braces for low complexity cases, patient demand and advances in technologies have led some orthodontists to broaden their use of Invisalign. Theoretical effects of the aligners such as a biteplate effect, incisor angulation control, and vertical control appeal to some practitioners. To date, no appropriate studies have been published on any of the aforementioned assertions with regard to Invisalign when used as a mode of Class II treatment. The purpose of this study is to evaluate the skeletal and dental effects of Class II nonextraction treatment in 49 adults using the Invisalign system of treatment and interarch elastics. Pre-treatment and post-treatment cephalometric analysis will allow a description of the changes in molar relationship, overjet and overbite correction, incisor angulation, vertical dimension, and changes of the occlusal plane. Of particular importance will be how this method of Class II treatment contrasts with conventional fixed appliance treatment using interarch elastics in adolescents and adults. Materials and Methods Sample The data in this retrospective clinical study were obtained by analyzing pre- (T1) and post-treatment (T2) lateral cephalograms of adult Class II Invisalign patients selected from the offices of two private practice orthodontists. The sample consisted of 28 adult Class II patients (18 females, 10 males) with a mean age at start of treatment of 35.5 years (Table 3.1, Tables A.1 and A.2). breakdown of the sample into divisions of Class II malocclusion reveals 19 Class II division 1 patients (14 females, five males, mean age at start of treatment: 37.7 years) and 9 Class II division 2 patients (four females, 50 A five males, mean age at start of treatment: 31.0 years). Twenty-one sets of records were from practice A and seven sets of records were from practice B. Patients were selected without consideration of post-treatment results. The criteria for patient selection were: • Pre-treatment occlusion of at least half-step unilateral or bilateral Class II molar malocclusion • At least 16 years of age at pre-treatment records • No congenitally missing teeth (excluding third molars) • Treatment completed without extraction of any permanent teeth (excluding third molars) • Treatment completed without orthognathic surgery • Patients treated solely with Invisalign and elastics throughout the course of treatment • Diagnostic pre- and post-treatment lateral cephalograms Table 3.1. Sample age, gender, and treatment duration. Patients Female:Male Mean Age at T1 Mean Tx Time 28 18:10 35y6m (16y5m – 62y5m) 25m (18m – 35m) 51 The present study was designed to analyze the posttreatment skeletal and dental changes of adult nonextraction Class II treatment with Invisalign. The goal of each treatment was to improve the overjet, overbite, and molar relationship by distal movement of the maxillary molars. Practice A utilized a sequential distalization method based on distal movement of the maxillary second molars by pitting them against the anchorage of the 12 anterior teeth.1,2 Class II elastics were then used to reinforce anchorage and sequentially move the buccal segments into a Class I relationship. Practice B mainly utilized Class II elastics to reinforce anchorage in molar rotation. Obtaining a sample from two practitioners was an attempt to limit variation in treatment technique. The decision to use practitioners with at least a “premium provider” standing with Invisalign assumed experience with the product. Data Collection Pre-treatment (T1) and post-treatment (T2) lateral cephalograms were collected for each patient. Each cephalogram was hand-traced by a single investigator. Eighteen hard-tissue and two reference landmarks were 52 identified on each cephalogram (Figure 3.1, Table A.3). The landmarks were then digitized with a Numonics Accugrid Digitizer (Numonics digitizing board, Model A30Bl.H, Numonics Corporation, Montgomeryville, PA) and analyzed using a customized cephalometric analysis (Table 3.2, Figure A.1-A.3) with Dentofacial Planner software (Dentofacial Planner version 5.23, Toronto, Canada). 19 1 18 20 2 17 3 4 16 13 15 14 6 5 12 7 8 9 11 10 Figure 3.1. Anatomical landmarks: Nasion (1); Anterior nasal spine (2); A point (3); Upper incisor apex (4); Upper incisor tip (5); Lower incisor tip (6); Lower incisor apex (7); B point (8); Pogonion (9); Gnathion (10); Menton (11); Inferior Gonion (12); Lower 1st molar distal contact (13); Lower 1st molar mesiobuccal cusp (14); Lower 1st premolar cusp (15); Upper 1st molar distal contact (16); Posterior nasal spine (17); Sella (18); Reference point 1 (19); Reference point 2 (20). 53 Table 3.2. Cephalometric measurements. Measurement Definition SNA Angle formed by SN and NA SNB Angle formed by SN and NB ANB Angle formed by NA and NB SN-MP Angle formed by SN and the mandibular plane (inferior gonion to menton) SN-PP Angle formed by SN and the palatal plane (ANS to PNS) SN-FOP Angle formed by SN and the functional occlusal plane (plane drawn through the occlusal contacts of the molars and premolars) U1-SN Angle formed by the longitudinal axis of the upper central incisor and SN IMPA Angle formed by the longitudinal axis of the lower central incisor and mandibular plane Overjet Horizontal distance from the upper central incisor tip to the lower central incisor tip along the functional occlusal plane Overbite Vertical distance from the upper central incisor tip to the lower central incisor tip perpendicular to the functional occlusal plane Molar relation Horizontal distance from the distal contact of the upper 1st molar to the distal contact of the lower 1st molar along the functional occlusal plane Hor U6 Horizontal distance from the distal contact point of the upper 1st molar to the Y-axis Ver U6 Vertical distance from the distal contact point of the upper 1st molar to the X-axis Hor L6 Horizontal distance from the distal contact point of the lower 1st molar to the Y-axis Ver L6 Vertical distance from the distal contact point of the lower 1st molar to the X-axis 54 X-Y Axis Coordinate System In order to provide graphic representation of treatment changes, a Cartesian coordinate system (X-Y axis) was constructed. Sixteen linear distances were measured from each coordinate system axis. X-axis measurements are horizontal distances from the vertical plane represented by a perpendicular line to the sella-nasion minus 7 degrees plane (Figure 3.2). Y-axis measurements are vertical distances from the horizontal plane represented by the sella-nasion minus 7 degrees plane (Figure 3.3). The corresponding points were then plotted in a scatter graph to show pre-treatment and post-treatment relationships. 55 SN – 7 perpendicular (Y axis) 1 SN – 7 (X axis) 2 17 3 4 16 15 14 13 6 5 12 7 8 9 11 10 Figure 3.2. Horizontal X-Y axis measurements: Nasion to Y-axis (1); ANS to Y-axis (2); A point to Y-axis (3); U1 apex to Y-axis (4); U1 tip to Y-axis (5); L1 tip to Y-axis (6); L1 apex to Y-axis (7); B point to Yaxis (8); Pogonion to Y-axis (9); Gnathion to Y-axis (10); Menton to Yaxis (11); Inferior gonion to Y-axis (12); Distal of L6 to Y-axis (13); Mesiobuccal cusp of L6 to Y-axis (14); L4 tip to Y-axis (15); Distal of U6 to Y-axis (16); PNS to Y-axis (17). 56 SN – 7 perpendicular (Y axis) 1 SN – 7 (X axis) 2 17 3 4 16 13 14 15 6 5 12 7 8 9 11 10 Figure 3.3. Vertical X-Y axis measurements: Nasion to X-axis (1); ANS to X-axis (2); A point to X-axis (3); U1 apex to X-axis (4); U1 tip to X-axis (5); L1 tip to X-axis (6); L1 apex to X-axis (7); B point to Xaxis (8); Pogonion to X-axis (9); Gnathion to X-axis (10); Menton to Xaxis (11); Inferior gonion to X-axis (12); Distal of L6 to X-axis (13); Mesiobuccal cusp of L6 to X-axis (14); L4 tip to X-axis (15); Distal of U6 to X-axis (16); PNS to X-axis (17). 57 Statistical Methods Data was collected and organized into spreadsheet format using Microsoft Office Excel 2007. Statistical analysis was performed using SPSS statistical analysis software (PASW Statistics Version 18.0, SPSS Inc., Chicago, IL). Paired t-tests were used to evaluate differences in pre- and post-treatment measurements. Means and standard deviations were used to describe central tendencies and dispersion. To test intra-examiner reliability, 6 sets of pre- and post-treatment radiographs were randomly selected for retracing and re-measuring. Cronbach’s Alpha test for reliability showed that intra-class correlation was 0.961 (Appendix A.4). This value is above the generally accepted 0.800 value indicating a high reliability of measurements. Results Cephalometric Comparison Descriptive statistics of 15 variables were calculated for pre-treatment (T1), post-treatment (T2), and overall treatment changes (Table 4.1, Table 4.2). Ten of the 15 measured variables showed a statistical significance in overall treatment change. Statistically significant 58 (p<.05) differences were found in overall treatment change for SN-MP and U1-SN. Statistically significant (p<.01) differences were found in overall treatment change for SNB, ANB, IMPA, overjet, overbite, molar relationship, upper molar linear distance from the Y-axis, and lower molar linear distance from the Y-axis measurements. A “p-value” of less than .05 indicates a 95% confidence in the data and a “p-value” of less than .01 indicates a 99% confidence in the data. The other differences between groups were not statistically significant. Anteroposterior skeletal treatment changes were represented by insignificant change of the SNA, the SNB moving anteriorly 0.8 degrees, and the ANB decreasing 1.1 degrees. Vertical skeletal treatment changes were represented by a 0.7 degree decrease in SN-MP and insignificant change in SN-PP and SN-FOP angles. Maxillary dental changes showed the U1-SN angle decreased 2.7 degrees. The upper molars moved distally 1.4 mm and intruded 0.3 mm. Mandibular dental changes showed the IMPA decreased 1.1 degrees. The lower molars moved mesially 0.6 mm and intruded 0.3 mm. Dental relationship changes showed a decrease in overjet of 1.2 mm, decrease in overbite of 1.2 mm, and a Class I molar movement of 1.8 mm along the functional occlusal plane. 59 Table 3.3. Descriptive statistics of T1 and T2. Pre-treatment (T1) Measurement Post-treatment (T2) Mean S.D. Mean S.D. SNA (o) 83.9 4.4 83.5 4.5 SNB (o) 78.6 3.7 79.4 3.5 5.3 2.2 4.2 2.6 27.3 6.7 26.6 6.6 SN-PP ( ) 4.9 4.4 4.6 4.5 o 11.0 4.5 10.4 4.8 102.3 9.3 99.6 5.2 Hor U6 (mm) 37.3 5.2 35.9 5.2 Ver U6 (mm) 60.4 4.2 60.1 4.3 IMPA (o) 98.5 5.5 97.4 5.1 Hor L6 (mm) 35.8 5.6 36.4 5.8 Ver L6 (mm) 63.9 4.1 63.6 3.8 Overjet (mm) 4.8 2.1 3.6 1.2 Overbite (mm) 4.3 2.1 3.1 1.3 -1.4 0.9 0.4 0.7 A-P o ANB ( ) Vertical SN-MP (o) o SN-FOP ( ) Maxillary dental U1-SN (o) Mandibular dental Dental Relation Molars (mm) 60 Table 3.4. Descriptive statistics of treatment changes. Positive values represent mesially-directed or extrusive movements. Negative values represent distally-directed or intrusive movements. T1-T2 Difference Measurement Mean S.D. Significance SNA (o) -0.4 1.2 0.107 A-P o SNB ( ) 0.7** 0.9 <0.001 ANB (o) -1.1** 1.0 <0.001 SN-MP (o) -0.7* 1.5 0.041 SN-PP (o) -0.3 1.5 0.252 o -0.6 1.9 0.086 U1-SN (o) -2.7* 6.3 0.034 Hor U6 (mm) -1.4** 0.8 <0.001 Ver U6 (mm) -0.3 0.8 0.179 -1.1** 1.9 0.006 0.6** 0.7 <0.001 -0.3 0.6 0.139 Overjet (mm) -1.2** 1.8 0.005 Overbite (mm) -1.2** 1.7 0.001 1.8** 0.8 <0.001 Vertical SN-FOP ( ) Maxillary dental Mandibular dental IMPA (o) Hor L6 (mm) Ver L6 (mm) Dental Relation Molars (mm) * denotes changes are significant at p<.05 ** denotes changes are significant at p<.01 61 X-Y Axis Coordinate System Inferential statistics were not run for all of the X-Y axis variables due to a deficient variable-to-sample ratio. In order for variables to have statistical significance the variable-to-sample ratio should ideally be 1:10. However, graphic representations of the X-Y axis findings are used in the discussion to help describe treatment changes (Figure 5.1, Figures A.4-A.7). 62 Figure 3.4. Graphic overlay of treatment changes. Dashed black lines represent the pre-treatment graphic (T1) and solid red lines represent the post-treatment graphic (T2). 63 Discussion This study was designed to evaluate the skeletal and dental effects of adult Class II nonextraction treatment using the Invisalign system of treatment with interarch elastics. To date, no study on this topic has been published in the refereed orthodontic literature. Skeletal A-P Changes Significant treatment changes were found for the SNB angle and the ANB angle. The SNB angle increased and the ANB angle decreased indicating improvement in the maxillomandbiular relationship. The observed reduction in SNA angle was not statistically significant. This indicates that skeletal improvement toward Class I was primarily due to the mandible moving mesially. These results generally agree with the literature for Class II treatment in adult patients.3-6 Without significant maxillary skeletal growth, A point tends to move distally or remain unchanged. The Class II correction force vector attempts to move the mandible and mandibular dentition mesially. These A-P skeletal changes can result in a decreased ANB angle.3,6-8 The graphic representation of a T1 and T2 overlay show the aforementioned changes. The T2 A point is positioned 64 distally to that of T1 and B point is positioned mesially. A slight projection of the T2 pognonion is also evident. Skeletal Vertical Changes The SN-MP angle showed a statistically significant decrease. A generally unwanted side effect of Class II treatment is the tendency for an increased vertical dimension due to elastic wear. As this study features non- growing patients treated without extractions or headgear, the decrease in vertical dimension is of interest. A possible explanation of this could be the constant presence of aligner material between the opposing dental arches. These results contrast with the majority of the Class II literature as most of the studies reviewed showed an increase in SN-MP.4,5,9-13 Only three of the studies reviewed showed a decrease in SN-MP.6,13,14 The observed reduction of SN-PP angle and SN-FOP were not statistically significant. The Class II literature shows a general increase in SN-OP.4-7,10,12,15 The most significant increases in SN-OP were noted in adult extraction studies.4,5,12 The graphic overlay depicts a slight decrease along the palatal plane and mandibular plane for T2 compared to T1. 65 Maxillary Dental Changes Statistically significant changes were found for the U1-SN angle and the linear distance of the upper molars to the Y-axis. The U1-SN angle decreased contributing to a reduction in overjet. These results agree with the studies that measured U1-SN change.6,10,13 The upper molars showed movement distally for every patient in the study contributing to an improvement in molar relationship. The vertical measurement from the upper molar to the X-axis was not statistically significant. These results agree with the reviewed functional appliance adult Class II studies in that the upper molars moved distally throughout the course of treatment.13,16,17 Presumably due to maxillary growth, none of the adolescent Class II studies showed distalization of the upper molars and only one adult conventional fixed appliance study showed appreciable upper molar movement distally.3 The graphic overlay shows a mean T2 decrease in overjet and overbite through uprighting and intrusion of the upper incisors. The uprighting appears to be more movement distally of the incisal tip than the apex. 66 The graphic overlay also shows distalization of the upper molars with no notable extrusion. Mandibular Dental Changes Statistically significant changes were found for the IMPA and the linear distance of the lower molars to the Yaxis. The IMPA decreased slightly despite Class II elastic wear. This may be explained by interproximal reduction of the lower anterior dentition, which is often prescribed by the Invisalign treatment software to alleviate crowding and protrusion. Other contributing factors could be dispersion of the Class II elastics force across the entire mandibular dentition, complete faciolingual coverage of the dentition, and dental expansion built into the treatment plan. This finding is in contrast to nonextraction Class II conventional fixed appliance studies in the literature as all that measured showed an increase in IMPA.12,13,17,18 The functional appliance studies that measured IMPA showed seven to 10 times the amount of increase that was found in the current study.6,13 The lower molars showed movement mesially contributing to the molar relationship improvement. This finding agreed with the literature in direction of movement, but the current study featured less distance than the other 67 studies.5,10-14,16-20 The lower molars showed a statistically insignificant intrusion. Every previous Class II study reviewed that measured for a vertical dental component of the lower molars found extrusion.5,10,14,15,18,19 The T1 versus T2 graphic shows a slight retroclination of the lower incisors. The incisal tip features a movement distally as the apex appears unchanged. The T2 lower molars show movement mesially with no visible extrusion from their T1 position. Dental Relationship Changes Overjet, overbite, and molar relationship showed statistically significant changes. Overjet and overbite both decreased over the course of treatment. These findings are in agreement with the Class II literature, although the current study showed less overjet reduction by comparison.3,4,8,11,13,15-17,20 The upper molars moved distally and the lower molars moved mesially resulting in an improved molar relationship in every patient. This finding agrees with the Class II literature that measures for molar correction.4,11,15-17,20 The upper molars moved a distance nearly triple that of the lower molars indicating that molar correction was primarily due to distalization of the upper molars. 68 Despite statistical significance, treatment changes were relatively small and some did not exceed the cephalometric measurement error values presented by Baumrind and Frantz.21 Future studies in this area may see different results given recent advances in materials and software available to the clinician. Conclusions 1) The Invisalign system in conjunction with interarch elastics is a viable option for mild Class II nonextraction treatment in the adult dentition. 2) Class II treatment with the Invisalign system is capable of providing reliable upper molar distalization and improvement in molar relationship while maintaining an element of control in the vertical dimension. 69 References 1. Daher S, editor Invisalign treatment for Class II correction. 2012 Invisalign Summit; 2012; Las Vegas, NV. 2. Align Technology, Inc. Dr. Sam Daher's techniques for Class II correction with Invisalign and elastics: Align Technology, Inc.; 2011 [cited 2013 July 1, 2013]. 3. Proffit WR, Phillips C, Douvartzidis N. A comparison of outcomes of orthodontic and surgical-orthodontic treatment of Class II malocclusion in adults. Am J Orthod Dentofacial Orthop. 1992;101:556-565. 4. Cassidy DW, Jr., Herbosa EG, Rotskoff KS, Johnston LE, Jr. A comparison of surgery and orthodontics in "borderline" adults with Class II, division 1 malocclusions. Am J Orthod Dentofacial Orthop. 1993;104:455-470. 5. Vaden JL, Harris EF, Behrents RG. Adult versus adolescent Class II correction: a comparison. Am J Orthod Dentofacial Orthop. 1995;107:651-661. 6. Upadhyay M, Yadav S, Nagaraj K, Uribe F, Nanda R. Miniimplants vs fixed functional appliances for treatment of young adult Class II female patients: a prospective clinical trial. Angle Orthod. 2012;82:294-303. 7. Tovstein B. Behavior of the occlusal plane and related structures in treatment of Class II malocclusions. Angle Orthod. 1955;25:189-198. 8. Combrink FJ, Harris AM, Steyn CL, Hudson AP. Dentoskeletal and soft-tissue changes in growing Class II malocclusion patients during nonextraction orthodontic treatment. J South African Dent Assoc. 2006;61:344-350. 9. 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;86:269-276. 70 10. 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;114:430-436. 11. 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. 12. Harris EF, Dyer GS, Vaden JL. Age effects on orthodontic treatment: skeletodental assessments from the Johnston analysis. Am J Orthod Dentofacial Orthop. 1991;100:531-536. 13. Kinzinger G, Frye L, Diedrich P. Class II treatment in adults: comparing camouflage orthodontics, dentofacial orthopedics and orthognathic surgery--a cephalometric study to evaluate various therapeutic effects. J Orofac Orthop. 2009;70:63-91. 14. Liu J, Zou L, Zhao ZH, Welburn N, Yang P, Tang T, et al. Successful treatment of postpeak stage patients with class II division 1 malocclusion using nonextraction and multiloop edgewise archwire therapy: a report on 16 cases. Int J Oral Sci. 2009;1:207-216. 15. Jones G, Buschang PH, Kim KB, Oliver DR. Class II nonextraction patients treated with the Forsus Fatigue Resistant Device versus intermaxillary elastics. Angle Orthod. 2008;78:332-338. 16. Ruf S, Pancherz H. Dentoskeletal effects and facial profile changes in young adults treated with the Herbst appliance. Angle Orthod. 1999;69:239-246. 17. Ruf S, Pancherz H. Orthognathic surgery and dentofacial orthopedics in adult Class II Division 1 treatment: mandibular sagittal split osteotomy versus Herbst appliance. Am J Orthod Dentofacial Orthop. 2004;126:140-152. 18. Meistrell ME, Jr., Cangialosi TJ, Lopez JE, CabralAngeles A. A cephalometric appraisal of nonextraction Begg treatment of Class II malocclusions. Am J Orthod Dentofacial Orthop. 1986;90:286-295. 71 19. Janson G, Sathler R, Fernandes TM, Branco NC, Freitas MR. Correction of Class II malocclusion with Class II elastics: a systematic review. Am J Orthod Dentofacial Orthop. 2013;143:383-392. 20. 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. 21. Baumrind S, Frantz R. The reliability of head film measurements. 2. Conventional angular and linear measures. Am J Orthod. 1971;60:505-517. . 72 Table A.1. Sample ages and treatment duration. Pt # Age at T1 T1 Ceph T2 Ceph 1 26y 1m 11/24/09 12/15/11 25 2 53y 1m 3/18/10 7/31/12 20 3 16y 5m 4/6/10 5/8/12 25 4 23y 0m 9/2/10 5/24/12 20 5 39y 2m 10/7/08 10/7/10 24 6 34y 9m 2/19/09 5/2/11 27 7 52y 2m 6/7/10 3/5/12 21 8 47y 11m 3/9/10 4/11/12 25 9 16y 8m 7/20/10 5/8/12 22 10 29y 10m 1/5/10 6/7/12 29 11 36y 3m 1/25/10 11/17/11 22 12 35y 3m 1/26/11 7/12/12 18 13 24y 6m 11/16/09 8/25/11 21 14 18y 2m 10/21/09 6/5/12 32 15 54y 0m 9/29/09 4/6/11 19 16 45y 7m 1/11/11 11/27/12 22 17 17y 10m 8/11/08 5/10/10 21 18 26y 9m 7/17/08 8/24/10 25 19 18y 0m 6/10/10 3/14/12 21 20 24y 2m 12/7/09 8/1/12 33 21 31y 6m 11/4/09 9/20/11 22 22 46y 11m 11/15/10 1/21/13 26 23 34y 0m 11/8/10 8/7/13 33 24 62y 5m 4/13/10 10/10/12 30 25 39y 3m 5/28/09 9/3/11 28 26 36y 11m 12/8/10 7/30/13 32 27 51y 3m 11/13/08 10/11/11 35 28 52y 11m 11/22/11 7/18/13 20 73 Tx Time (mo) Table A.2. Sample Angle classification statistics. Patients Classification Females:Males Mean Age Range 19 Class II div 1 14:5 37y9m 16y5m – 62y5m 9 Class II div 2 4:5 31y0m 16y8m – 52y0m 28 All 18:10 35y6m 16y5m – 62y5m 74 Table A.3. Anatomical landmark definitions. Landmark Definiton Nasion The most anterior point of the frontonasal suture Anterior Nasal Spine The most anterior tip of the nasal spine A point The most posterior point in the concavity between the maxillary alveolar process and the anterior nasal spine Upper incisor apex The root apex of the upper central incisor Upper incisor tip The incisal tip of the upper central incisor Lower incisor tip The incisal tip of the lower central incisor Lower incisor apex The root apex of the lower central incisor B point The posterior point in the concavity between the mandibular alveolar process and the mandibular symphysis Pogonion The most anterior point of the mandibular symphysis Gnathion The point midway between the anterior and inferior points of the mandibular symphysis Menton The most inferior point of the mandibular symphysis Inferior Gonion The most inferior point of the mandibular gonial angle Lower 1st molar distal contact The distal contact point of the lower 1st molar Lower 1st molar mesiobuccal cusp The mesiobuccal cusp tip of the lower 1st molar Lower 1st premolar cusp The cusp tip of the lower 1st premolar Upper 1st molar distal contact The distal contact point of the upper 1st molar Posterior Nasal Spine The most posterior point of the bony hard palate Sella The center of the pituitary fossa Reference point 1 Point representing 15 mm on the cephalometric ruler Reference point 2 Point representing 0 mm on the cephalometric ruler 75 Sella-Nasion 1 2 3 Palatal Plane (ANS-PNS) Functional Occlusal Plane (Occlusal L6-Tip L4) Mandibular Plane (Go-Me) Figure A.1. Cephalometric plane measurements: Sella-Nasion to palatal plane angle (1); Sella-Nasion to functional occlusal plane angle (2); Sella-Nasion to mandibular plane angle (3). 76 3 4 1 2 5 Figure A.2. Cephalometric angular measurements: SNA (1); SNB (2); ANB (3); U1-SN (4); IMPA (5). 77 3 1,2 Figure A.3. Functional occlusal plane measurements: overjet (1); overbite (2), molar relationship (3). 78 Table A.4. Intra-class correlation values. Measurements at the initial time point (T1) were matched against a calibration measurement (call) at the initial time point. Intra-class Correlation Range Mean SNAT1-SNAcal 0.998 0.907-0.999 0.961 SNBT1-SNBcal 0.996 ANBT1-ANBcal 0.941 SN-MPT1-SN-MPcal 0.985 SN-PPT1-SN-PPcal 0.943 SN-FOPT1-SN-PPcal 0.944 U1-SNT1-U1-SNcal 0.999 IMPAT1-IMPAcal 0.933 OJT1-OJcal 0.918 OBT1-OBcal 0.994 MolarsT1-Molarscal 0.934 HorU6T1-HorU6cal 0.994 VerU6T1-VerU6cal 0.907 HorL6T1-HorL6cal 0.996 VerL6T1-VerL6cal 0.931 Measurement 79 Table A.5. Mean X-Y axis coordinates. Measurement Pre-treatment (T1) Horizontal Vertical Post-treatment (T2) Horizontal Vertical S-N 69.5 8.5 69.6 8.5 S-U6 37.3 -60.4 35.9 -60.1 S-L6 35.8 -63.9 36.4 -63.6 S-U1 tip 73.7 -67.2 71.8 -66.1 S-U1 apex 66.4 -45.1 65.2 -44.1 S-L4 tip 52.4 -63.5 52.5 -63.6 S-L1 tip 69.1 -62.3 68.9 -62.3 S-Pg 64.7 -97.0 65.0 -96.4 S-PNS 22.8 -41.0 22.6 -41.0 S-ANS 73.9 -39.7 73.7 -39.5 S-A point 70.6 -44.9 69.9 -44.7 S-L1 apex 59.2 -80.5 59.2 -80.6 S-B point 62.9 -81.1 63.3 -81.0 S-Gn 62.1 -100.8 62.4 -100.3 S-Go 4.7 -83.1 4.7 -83.0 S-Me 55.6 -101.2 55.9 -100.8 80 Pre+Treatment" 20.000& 0.000& 0.000& 10.000& 20.000& 30.000& 40.000& 50.000& 60.000& 70.000& 80.000& Nasion& U6& U1&4p& !20.000& U1&apex& L6& L4&4p& !40.000& Y"Axis" L1&4p& Pogonion& PNS& !60.000& ANS& A&point& L1&apex& B&point& !80.000& Gnathion& Gonion& Menton& !100.000& !120.000& X"Axis" Figure A.4. Graphic overlay of T1 measurements. 81 Post+treatment" 20.000& 0.000& 0.000& 10.000& 20.000& 30.000& 40.000& 50.000& 60.000& 70.000& 80.000& Nasion& U6& U1&4p& !20.000& U1&apex& L6& L4&4p& !40.000& Y"Axis" L1&4p& Pogonion& PNS& !60.000& ANS& A&point& L1&apex& B&point& !80.000& Gnathion& Gonion& Menton& !100.000& !120.000& X"Axis" Figure A.5. Graphic overlay of T2 measurements. 82 Figure A.6. Class II division 1 graphic overlay. Dashed lines represent the pre-treatment graphic (T1) and solid lines represent the post-treatment graphic (T2). 83 Figure A.7. Class II division 2 graphic overlay. Dashed lines represent the pre-treatment graphic (T1) and solid lines represent the post-treatment graphic (T2). 84 Vita Auctoris Brian Michael Klein was born on September 24, 1982 in Alton, Illinois. In 1985 he and his family moved to Mount Vernon, Illinois where he was raised and attended school. In 2006 he graduated from Indiana University in Bloomington, Indiana with a B.S. in Nutrition Science and a minor in Biology. In 2011 he received his D.M.D. with honors from Southern Illinois University School of Dental Medicine in Alton, Illinois. In December 2011 he married the beautiful Jane Alexandra Walde in St. Louis, Missouri. Following graduation from dental school in 2011, he began his studies at Saint Louis University in pursuit of a Master’s degree from the Orthodontics program. Upon graduation he and Jane will return to Mount Vernon where they’ll anxiously await the birth of their first child in February 2014. Brian will proudly join his father, Christopher, as a partner in Klein Orthodontics. 85