Conventional Versus Minimally Invasive Single-Tooth Preparations for Fixed Restorations: An In Vitro Comparison of Preparation Time, Tooth Structure Removal, and Trueness.

Abstract

Purpose: To compare conventional and minimally invasive single-tooth preparations in terms of preparation time, volume of tooth structure removed, and preparation trueness.

Materials and methods: Fifteen dentists with at least three years of clinical experience performed four different preparations (conventional crown and minimally invasive overlay on tooth 16; conventional crown and minimally invasive veneer on tooth 11) in randomized order on standardized typodont models (Frasaco). The preparation time was evaluated by video analysis, while tooth volume reduction and preparation trueness were assessed using digital scans and a 3D superimposition with a predefined digital reference model with a specific software (Geomagic Control X, Artec 3D). The data was analyzed using ANOVA and Wilcoxon's test with Bonferroni correction with significance level of 5% (α = 0.05).

Results: Minimally invasive preparations resulted in significantly shorter treatment times and lower volume of tooth structure removed compared to conventional preparations (p<0.05, Effect size 0.73). Mean preparation time was on tooth 16: 39.8 min (SD 13.2, 95%CI 32.5-47.1) for conventional crown preparation, 27.0 min (SD 8.1, 95%CI 22.6-31.6) for minimally invasive overlay; on tooth 11: 33.6 min (SD 11.0, 95%CI 27.5-39.7) for conventional crown preparation, and 15.4 min (SD 4.6, 95%CI 12.9-17.9) for minimally invasive veneer. Higher preparation trueness was seen for minimally invasive preparations for incisors compared to conventional preparations (p<0.001, Effect size 0.65).

Conclusions: Minimally invasive tooth preparations provide clear advantages in terms of clinical efficiency and tooth structure preservation both incisor and molar sites, and trueness for incisor sites.