# Accuracy of Marginal and Internal Adaptation of Advanced Lithium Disilicate Crowns Using Different Margin Designs (In Vitro Study)

## TL;DR

This in vitro study compares how well different margin designs affect the fit of lithium disilicate crowns, finding that vertiprep designs offer the best internal fit.

## Contribution

The study provides new empirical evidence on the performance of vertiprep margin designs in lithium disilicate crowns.

## Key findings

- Vertiprep margin design showed the least marginal adaptation and best internal fit.
- Chamfer and vertiprep designs had similar marginal gaps.
- Rounded shoulder design had the largest marginal gap.

## Abstract

Advanced lithium disilicate glass ceramics offer excellent esthetics, but conservative crown preparations are not always the preferred choice. Various margin designs are available; however, more conservative vertical preparations (vertipreps) have less scientific evidence supporting their esthetic outcomes compared to shoulder or chamfer designs.

To assess the marginal adaptation and internal fit of crowns fabricated from advanced lithium disilicate (CEREC Tessera) using computer‐aided design and manufacturing (CAD/CAM) with three distinct margin designs.

Three mandibular molar typodont teeth were prepared with three finish line designs: chamfer 0.5 mm (C), rounded shoulder 1 mm (RS), and vertiprep 0.2 mm (V) using a modified dental surveyor for standardization. Silicone replicas were used to create epoxy resin dies. Twenty‐four crowns were produced on the replicated resin dies, with eight crowns for each finish line design (n = 8). Preparations were scanned using an intraoral scanner (Carestream Dental LLC, 3625 Cumberland Blvd., Ste. 700, Atlanta, GA 30339), and advanced lithium disilicate (Tessera) crowns were milled via CAD/CAM. Crowns were cemented onto their respective dies, and marginal adaptation was measured using a stereomicroscope; then, crowns were sectioned using a microtome to evaluate internal fit.

One‐way ANOVA showed a significant difference in the marginal adaptation among groups (p  < 0.001). Group RS had the largest gap (125.45 ± 12.11 µm), followed by Group C (107.31 ± 9.25 µm) and Group V (101.79 ± 9.01 µm). Internal fit also differed significantly (p  < 0.001), with Group V having the smallest gap (70.09 ± 8.45 µm), followed by Group RS (87.85 ± 6.82 µm) and Group C (94.45 ± 9.21 µm).

The vertiprep showed the least marginal adaptation and best internal fit compared to shoulder and chamfer designs, with no significant difference in marginal gap between vertiprep and chamfer.