engleski

Dental arch form and tooth-size discrepancy in Class I and Class II malocclusions using 3D virtual models

Objective: To analize could dental arch forms be used in prediction of tooth-size discrepancies in Class I and II malocclusions.Materials and methods: Samples included randomly selected plaster dental casts of 85 patients (41 Class I mean age 14.4±0.3 (18 males and 23 females) and 44 Class II 14.5±0.4 (19 males and 25 females)) from the Department of Orthodontics, School of Dental Medicine, University of Zagreb, Croatia. Dental models were scanned and digitized using ATOS II SO ("small objects") scanning technology (GoM mbH, Braunschweig, Germany), and 3D virtual objects were created. Twelve points were digitally marked on each model (representing midpoint of the facial axis of the clinical crown), using ATOS viewer version 6.A.2 software. The following measurements were calculated for upper and lower dental arches: anterior Bolton ratio, overall Bolton ratio, width/depth ratio, molar width/depth ratio, canine / molar depth ratio, canine / molar width ratio. Data were analyzed using SPSS 10.0 software. Multiple regresion was used for analysis, a level of p<0.05 was considered statisticaly significant.Results: Maxillary molar width/depth ratio (p=0.036) and mandibular canine/molar depth ratio (p=0.012) could be used in prediction of anterior Bolton ratio in class I malocclusions, but the regression model accounted for only 37 % of the variance in anterior Bolton ratio (p = 0.041). While controlling for all other variables in regression model the independent contribution of maxillary molar width / depth ratio to the prediction of anterior Bolton ratio is 9.4% (r=0.307), and mandibular canine / molar depth is 13.9% (r=-0.373). In class II malocclusions archform can not be used in prediction of Bolton ratio.Conclusion: Dental arch forms are poor predictors of tooth size discrepancies.

arch form; tooth-size discrepancy; virtual model

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