# Influence of composite resin core buildup translucency on the accuracy of an anterior CAD-CAM bridge fabricated with a digital impression

## TL;DR

This study shows that using low translucency composite resin improves the accuracy of digital impressions for CAD-CAM dental bridges compared to high translucency composites.

## Contribution

The study demonstrates that composite translucency significantly impacts the accuracy of intraoral scans used for CAD-CAM restorations.

## Key findings

- Low translucency composite (EX) showed better trueness and fewer points over the 50μm threshold compared to high translucency composite (A3).
- CAD/CAM restorations on high translucency composites had a poorer fit compared to those on low translucency composites.
- Applying appropriate compensation during restoration design can improve results when using high translucency composites.

## Abstract

Composite resin build-up translucency affects the accuracy of digital impressions generated by an intraoral scanning system (IOS). Here, we evaluated the influence of composite core translucency on the accuracy of a CAD-CAM bridge (Fixed Partial Denture) using an intraoral scanner.

We investigated the accuracy (the trueness and precision) of 2 different composites (EverX Flow-EX and G-aenial Universal Injectable A3) for core build up in 3-unit CAD/CAM bridge on anterior teeth using an intra-oral scanner (Trios 3, 3Shape) and injectable technique. The fitting of crown within the clinical acceptable threshold of final restoration was also confirmed by CBCT superimposition.

The results illustrated that composite with high translucency (A3) expressed lower trueness value than one with low translucency. With a clinically acceptable threshold<50μm, the percentage of points over the threshold was lower in composite group with low translucency (EX). CAD/CAM restorations on high translucency composite-reconstructed abutments showed a poor fit compared with the low translucency group on both abutments.

The use of low translucency reconstructive materials helps to reduce the errors of IOS, and at the same time, appropriate compensation should be used when designing restorations to provide the most accurate results.
Clinical Significance: • Composite with high translucency (A3) expressed lower trueness value than one with low translucency (EX). • With a clinically acceptable threshold<50μm, the percentage of points overcoming the threshold was lower in composite group with low translucency (EX). • Appropriate compensation should be applied when designing CAD/CAM restoration to achieve the best results.

Key words:Accuracy, intraoral-scanner, digital dentistry, resin composite, bridge prosthesis, CAD/CAM.