The Influence of Labio-lingual and Mesio-distal Anterior Tooth Dimensions on Inter-arch Relationships: A Modified Anterior Bolton Analysis

Abstract

Introduction: Tooth size and morphology of anterior teeth influence inter-arch relationships. The Bolton analysis uses tooth width to calculate a sum of mandibular to maxillary tooth widths ratio necessary for proper occlusion. Several parameters not factored in the Bolton analysis influence occlusion such as tooth thickness. This study sought to use 3D modeling to develop and assess a tooth size analysis that encompasses labio-lingual thickness as well as mesio-distal width of anterior teeth. Methods: The role of tooth thickness in inter-arch relationships was studied using simulations in a 3D modeling software (SuresmileTM). To develop a new chart of inter-arch ratios based on tooth thickness, a series of simulations were produced with varying tooth thicknesses and widths. The new ratios were evaluated on records from 50 patients. Results: Findings from the simulations suggest that the ideal tooth thickness remains approximately 2mm if the overall tooth width of the dentition increases and the inter-arch anterior ratio is maintained. The thickness-adjusted anterior mandibular to maxillary tooth ratio ranges from 0.70 to 0.79 depending on the tooth thickness. This thickness-adjusted ratio provides a superior prediction for the sum of anterior tooth width compared to the Bolton analysis. Conclusion: Tooth thickness does affect inter-arch tooth width ratios and anterior occlusion. A thickness-adjusted ratio can be used to more accurately predict anterior tooth dimensions necessary to achieve proper occlusion.