Tooth Size Discrepancies in Various Malocclusions: A literature Review

Background: Tooth-size discrepancy (TSD) is an important factor in orthodontic diagnosis and treatment planning, affecting interarch relationships, occlusal stability, and achievement of ideal overjet, overbite, and intercuspation. Bolton analysis is the most commonly used method for assessing interarch tooth-size discrepancies; however, its applicability across different malocclusion groups and populations remains uncertain. Objective: To review the literature on tooth-size discrepancies among different Angle’s malocclusion groups and evaluate the influence of ethnicity and sex on Bolton tooth-size ratios. Materials and Methods: A narrative literature review was conducted using PubMed, Cochrane Library, and Google Scholar databases. Studies published between January 2000 and December 2023 were searched using the keywords" tooth-size discrepancy," "Bolton analysis," "Angle’s malocclusion," "Class I," "Class II," and "Class III malocclusion."Seminal studies published before 2000, including Bolton’s original investigations, were also considered. Original research articles, observational studies, retrospective studies, systematic reviews, and meta-analyses evaluating tooth-size discrepancies were included, whereas case reports, editorials, duplicate studies, and articles lacking relevant data were excluded. A total of 22 studies were included for qualitative synthesis. Conclusion: The reviewed literature indicates that clinically significant anterior tooth-size discrepancies occur in approximately 16%–38% of orthodontic patients. Although variations have been reported among Class I, II, and III malocclusions, the association between TSD and malocclusion type remains inconclusive. In contrast, consistent differences in Bolton ratios have been observed among ethnic populations, while sex has minimal influence on tooth-size proportions. Therefore, routine Bolton analysis and development of population-specific standards may improve diagnostic accuracy and individualized orthodontic treatment outcomes.