TAM KRON PREPARASYONUNDA BİTİŞ SINIRI VE YÜZEY GEOMETRİSİNİN DİJİTAL ÖLÇÜ HASSASİYETİNE ETKİSİ: İN VİTRO ÇALIŞMA

Abstract

GÜNEL A, The effect of finish line and surface geometry on digital impression accuracy in full crown preparation: An in vitro study. Hacettepe University Faculty of Dentistry, Thesis in Prosthodontics, Ankara, 2022 Different preparation designs have been reported to affect accuracy in digital impressions obtained with intraoral scanners. However, studies on the effect of the geometry of the finish line and the sharp surfaces that may occur during the preparation on the digital impression accuracy are insufficient. This study aims to examine the effect of the finish line and surface geometry on digital impression accuracy in full crown preparation. For this purpose, six prepared tooth models with three different finishing lines (shoulder, chamfer, rounded shoulder) and two different occlusal geometries (sharp and rounded) were created. In each group, a reference model was obtained using digital data from an industrial scanner (Atos II TripleScan). Models were scanned with three different intraoral scanners (iTero Element 2, Trios 4, Medit i500) (n=10). Impression accuracy was evaluated by superimposing the reference data with the digital impression data obtained from intraoral scanners by the best-fit program. R software (version 4.1.2) was used for the statistical analysis of the data. Differences between groups and scanners were analyzed using the Mann-Whitney U non-parametric test. In case of a difference between the groups, Conover paired comparison test was applied. The statistical significance level for all analyzes was accepted as p<0.05. For all intraoral scanners, models with shoulder finish lines showed higher deviation values (p<0.05). Models with sharp occlusal geometry showed higher deviation values compared to rounded ones (p<0.05). For all groups clinically acceptable digital impressions were obtained.