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

PLoS One. 2026 Jan 16;21(1):e0340793. doi: 10.1371/journal.pone.0340793. eCollection 2026.

Abstract

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

Materials and methods: 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.

Results: 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).

Conclusion: 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.

MeSH terms

  • Computer-Aided Design
  • Crowns*
  • Dental Prosthesis Design* / methods
  • Humans
  • Molar
  • Printing, Three-Dimensional*
  • Software