# Evaluation of the marginal and internal gaps in 3D-printed interim crowns using different finish line detection methods: An in vitro study

## TL;DR

This study compares the accuracy of automatic and semi-automatic finish line detection methods in 3D-printed crowns using Dentbird and CEREC software.

## Contribution

The study evaluates Dentbird's automatic finish line detection for interim crowns and compares it to the CEREC system.

## Key findings

- Automatic Dentbird methods showed significant differences in fit compared to CEREC.
- Semi-automatic methods in both systems showed no significant differences in fit.
- All tested crown fits were within clinically acceptable ranges.

## Abstract

This study aimed to evaluate the accuracy of the Dentbird crown software in automatically detecting the finish line for interim crowns.

A mandibular first molar typodont model with a chamfer finish line was prepared and scanned ten times, resulting in ten STL files. The finish line for each file was detected using both automatic and semi-automatic methods in two software programs: the CEREC InLab system and Dentbird software. The internal and marginal gaps were measured at four locations: mesial, distal, buccal, and lingual- using the silicone replica technique. One-way analysis of variance (ANOVA) and post-hoc analyses (α = 0.05) were performed to detect statistical differences in the marginal and internal gaps among the groups.

The results revealed significant differences in internal and marginal gaps between the automatic methods of the Dentbird software and the CEREC system (p < 0.05). However, no significant differences were found in the semi-automatic methods between the two systems (p > 0.05). Although the fits of crowns automatically designed by Dentbird software were inferior to those of the semi-automatic method by Dentbird software and the CEREC In Lab system, the values of all four groups were within the clinically acceptable range (<120 µm).

The internal and marginal fit of crowns designed using the automatic and semi-automatic modes in Dentbird, a freely available CAD platform, fell within the range of traditional clinical acceptability. Hence, automatically generated crowns may be considered appropriate for immediate provisional applications, the semi-autonomic finishing line detection can be used for long term crowns in clinical practice.