In Vitro Assessment of Tooth Reduction in Incisors, Canines, and Bicuspids Using Horizontal (Chamfer) and Vertical (BOPT and BOPTm) Finishing Lines

Abstract

Introduction: The selection of the finishing line for dental abutment preparation is influenced by various factors such as therestorative material, esthetic demands, procedural simplicity, and the clinician's experience. However, fundamental principlesof tooth preparation, including the preservation of tooth structure, retention form, abutment strength, and margin integrity, areparamount in ensuring predictable and successful prosthodontic outcomes.Objective: This study aims to evaluate the extent of tooth reduction in upper central incisors, canines, and premolars when threeabutment preparation techniques—horizontal (chamfer) and vertical (biologically oriented preparation technique (BOPT) andmodified BOPT (BOPTm))—are applied.Materials and Methods: Ninety upper maxillary dental models were used, subdivided into three groups: 30 for right centralincisors, 30 for right canines, and 30 for right first premolars. Each group was further divided based on the finishing line ap-plied: horizontal (chamfer), vertical (BOPT), and modified vertical (BOPTm). Tooth reduction was quantified by subtracting thevolume of the unprepared tooth from that of the prepared tooth. Statistical differences between the groups were analyzed usingunivariate analysis of variance (ANOVA) with a significance level set at 0.05.Results: Tooth shape significantly influenced the amount of dental tissue removed. For square-shaped teeth, the volume ofreduction was relatively consistent across all techniques. However, in triangular-shaped teeth, the choice of technique notablyimpacted the amount of tooth reduction. Among the finishing lines, the BOPT technique resulted in the least tooth reduction inboth incisors and canines, while the modified BOPT (BOPTm) was the most aggressive. No significant differences were observedin the premolar group. Additionally, both chamfer and modified BOPT lines required less tooth reduction in premolars comparedto incisors and canines. The BOPT technique did not show significant differences in tooth reduction across the different toothtypes.Conclusion: The BOPT finishing line was the least invasive in terms of tooth reduction for incisors and canines, while themodified BOPT technique (BOPTm) resulted in more aggressive tooth preparation. In the premolar group, both chamfer andmodified BOPT lines required less tooth reduction compared to the incisors and canines. No significant variations in reductionwere observed when the BOPT technique was applied to different tooth types.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in anymedium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.© 2025 The Author(s). Journal of Esthetic and Restorative Dentistry published by Wiley Periodicals LLC.