Longitudinal Evaluation of the Intermaxillary Relationship in Class III Malocclusions
Fengshan Chena; Kazuto Teradab; Liping Wuc; Isao Saitod
ABSTRACT Objective: To analyze the sagittal, vertical, and transverse relationship of the maxilla and mandible in Japanese girls with Class III malocclusions. Materials and Methods: This longitudinal study utilized biannualposteroanterior and lateral cephalograms of 44 untreated subjects from age 8 to 14 years (Class I, 23 girls; Class III, 21 girls). Sagittal and vertical growths were analyzed on the basis of lateral cephalograms, and transverse growth was analyzed on the basis of posteroanterior cephalograms. Results: There was no signiﬁcant difference in sagittal intermaxillary relationships in Class III malocclusion fromage 8 to 14 years, whereas signiﬁcant difference in vertical and transverse intermaxillary relationships appeared with ages during this period. When comparing Class III to Class I malocclusions at the same age point, there were signiﬁcant differences in sagittal and transverse intermaxillary relationships, whereas signiﬁcant difference in vertical intermaxillary relationship appeared after 12 yearsof age. Conclusion: The results suggest that the sagittal intermaxillary relationships in Class III malocclusions were established before 8 years of age and remained through puberty and that the vertical and transverse intermaxillary relationships in Class III malocclusions changed with ages from 8 to 14 years. KEY WORDS: Class III malocclusion; Growth; Intermaxlliary relationship
INTRODUCTIONClass III malocclusions are common clinical problems among Asian patients. Yang1 discovered that 40– 50% of orthodontic patients in Korea sought treatment for Class III malocclusions. Kitai et al2 reported that 5– 20% of the Japanese population have the characteristics of a Class III malocclusion. Similarly, Johnson et al3 discovered that 23% of Chinese children have Class III malocclusions.
aGraduate Doctoral Student, Niigata University, Department of Orthodontics, Niigata, Japan; Lecturer, Department of Orthodontics, Dental School, Tongji University, Shanghai, China. b Associate Professor, Niigata University, Medical and Dental Hospital, Niigata, Japan. c Associate professor, Department of Orthodontics, dental school, Tongji University, Shanghai, China. d Professor, NiigataUniversity, Department of Orthodontics, Niigata, Japan. Corresponding author: Dr. Fengshan Chen, Niigata University, Department of Orthodontics, Gakkojodori 2-5274, Niigata, Niigata 9518126 Japan (e-mail: email@example.com)
Accepted: December 2005. Submitted: October 2005. 2006 by The EH Angle Education and Research Foundation, Inc.
DOI: 10.2319/102005-371 955
The dentofacial disharmonyassociated with Class III malocclusions is challenging in both diagnosis and treatment. Treatment decisions and their successes or failures rely heavily on the future growth potential in the Class III individual.4,5 An understanding of the craniofacial growth behavior, especially the relative intermaxillary relationship (IR), in Class III patients will help in determining the timing and mechanics oftreatment. Longitudinal data is of great value to orthodontists who are interested in the detailed study of facial growth. The use of normative cephalometric standards obtained for subjects of one age group when making a diagnosis of individuals who might be of a completely different age group could adversely inﬂuence both the diagnosis and the treatment plan.6 A number of studies, predominantlybased on Class I samples, have addressed the development of the intermaxillary relationships.7–12 In contrast, few studies have focused on the IR and growth in Class III malocclusions. Sugawara et al13 studied the sagittal IR of Japanese male adolescents from 10 to 15 years of age and found the skeletal Class III malocclusions had neither excessive mandibular growth nor deﬁcient maxillary