Vertical Versus Horizontal Finishing Lines for Dental Preparations: A Systematic Review With Meta-Analysis

To evaluate the influence of horizontal and vertical dental preparation techniques on tooth-supported fixed restorations, with specific focus on survival and success rates, periodontal-related variables, and patient-reported outcome (PROs) measures.

A comprehensive literature search of relevant randomized and controlled clinical trials (RCTs/CCTs), prospective/retrospective cohort studies, and case series with a minimum follow-up period of 3 years was performed across electronic databases (Medline, Embase, and Cochrane) up to January 2024. Primary outcomes included success and survival rates, and secondary outcomes included periodontal variables, both mechanical and biological complications, and PROs. Two reviewers independently conducted study selection, data extraction, and quality assessment. Of the 837 articles initially identified, 19 were included in the final analysis. A meta-analysis was conducted to compare the preparation techniques using survival and success rates as the main outcomes. Additionally, periodontal variables were analyzed.

The included studies varied in design, follow-up duration, restoration type, and materials used. Survival rates showed no significant differences between vertical and horizontal techniques (risk ratio (RR) 0.96-1.04, p = 0.95). Additionally, success rates (RR 0.93-1.14, p = 0.53) and periodontal variables also showed varied results with no clear preference for either technique.

Both the horizontal and vertical preparation techniques exhibited comparable survival and success rates for dental restorations. Given that there was no significant difference in outcomes between the two, the choice of technique may depend on the clinician's preference and specific clinical scenarios.