Differences in molar relationships and occlusal contact areas evaluated from the buccal and lingual aspects using 3-dimensional digital models

Abstract

ObjectiveThe aims of this study were to use a 3-dimensional (3D) system to compare molar relationship assessments performed from the buccal and lingual aspects, and to measure differences in occlusal contact areas between Class II and Class I molar relationships.MethodsStudy casts (232 pairs from 232 subjects, yielding a total of 380 sides) were evaluated from both the buccal and lingual aspects, so that molar relationships could be classified according to the scheme devised by Liu and Melsen. Occlusal contact areas were quantified using 3D digital models, which were generated through surface scanning of the study casts.ResultsA cusp-to-central fossa relationship was observed from the lingual aspect in the majority of cases classified from the buccal aspect as Class I (89.6%) or mild Class II (86.7%). However, severe Class II cases had lingual cusp-to-mesial triangular fossa or marginal ridge relationships. Mean occlusal contact areas were similar in the Class I and mild Class II groups, while the severe Class II group had significantly lower values than either of the other 2 groups (p < 0.05).ConclusionsBuccal and lingual assessments of molar relationships were not always consistent. Occlusal contact areas were lowest for the Class II-severe group, which seems to have the worst molar relationships - especially as seen from the lingual aspect.

Evaluation of Occlusal Contacts among Different Groups of Malocclusion using 3D Digital Models

“…Patients with class I division 1 malocclusion had larger occlusal contacts than subjects in other malocclusion groups. This result is in agreement with the two previous studies 8,13 which evaluated occlusal contacts among different malocclusion groups and can be explained by that class I division 1 malocclusion is the closest to normal occlusion with regard to the 3D localization of posterior teeth between the two jaws. The occlusal contacts of class III subjects were significantly less than those of other malocclusion groups.…”

“…Owens et al demonstrated a increasing area of occlusal contact or very-near contact from a class III malocclusion group, through a class II group, a class I group to the most occlusal contact in subjects with good occlusion. 8 This was also supported by Jang et al who measured differences in occlusal contact areas between class II and I molar relationships, 13 but these two studies did not evaluate the possible differences between class II division 1 and division 2 malocclusions and the sample size in Owens study was very small (only six cases in the class III group). Assessment of the magnitude of occlusal contacts has been first approached by using articulating paper, shim stocks, occlusal waxes or silicone impressions, but these methods have not proved their efficacy in reproducing occlusal contacts accurately.…”

“…Anterior crowding mm (Mean ± SD) 3.6 ± 0.7 1.8 ± 0.5 2.1 ± 0.3 1.5 ± 0.5 SD: indicates standard deviation using Rapidform™ program, whereas the current work is an attempt to transform occlusalgram data (provided by O3DM™ program) into numerical values reflecting mesh points in contact (or semi-contact) as an indicator of the magnitude of occlusal contact in a sample of refereed orthodontic patients. In the present study, OCSAs were derived from calculations based on Rapidform™ program which has been used widely in the orthodontic literature for landmark-based measurements or superimpositioning purposes 16 or even for surface area 13 or volumetric assessments. 24 Therefore, the Rapidform-based OCSAs method was considered the gold-standard to which OCMPs values were compared.…”

“…the occlusal contact surface areas OCSAs) were calculated using a Boolean function embedded in this software. 13 The figures…”

“…premolars and molars) for each patient. 13 Reviewing the literature reveals a paucity of research evaluating occlusal contacts between malocclusion groups using 3D digital models. Furthermore, the possible relationships between occlusal contacts and other dental characteristics have not been yet evaluated well.…”