Preliminary biometric analysis of mesiodistal tooth dimensions in subjects with normal occlusion

• The Bolton index is useful for identifying dentodental discrepancies.
• Cluster analysis enables divisions into general classes.
• Multivariate analysis showed 3 clusters of tooth-dimension measurements.
• Statistically significant tooth-measurement differences were found between the sexes.
• Significant proportionality was seen between maxillary and mandibular arch clusters.

IntroductionThe aims of this study were to confirm the efficacy of the Bolton index in a group of natural Class I white Italian patients with complete dentition, minimal crowding, and no previous orthodontic treatment, and to evaluate the mesiodistal tooth dimensions with multivariate cluster analysis.MethodsTooth measurements were obtained from a sample of 56 patients with normal occlusion, with a normal Bolton index (22 men, 34 women; mean age, 27.8 years), without previous orthodontic treatment or prosthetic or Class II restorations. Maxillary and mandibular measurements were analyzed separately in the sexes. Clustering was performed using the partitioning around medoid algorithm and principal component analysis-based transformed data. Statistical analysis was conducted.ResultsThe multivariate analysis showed 3 distinct clusters of both maxillary and mandibular tooth measurements in the male and female subjects. Statistically significant differences were found between the sexes in terms of average tooth measurements, and there was significant proportionality between the maxillary and mandibular arch clusters.ConclusionAlthough the Bolton index is useful for identifying dentodental discrepancies in most patients, cluster analysis enabled the mandibular and maxillary tooth dimensions of the male and female subjects to be divided into 3 general classes (clusters) and the precise location of the discrepancies to be pinpointed.