Influence of Different Marginal Preparation Designs and Materials on the Marginal Integrity and Internal Adaptation of Endocrown Restorations

Abstract

ABSTRACT Objective: This in vitro study was performed to assess the marginal accuracy and internal adaptation of CAD/CAM fabricated endocrowns restoring endodontically treated molars with two different designs and materials. Materials and methods: Forty extracted maxillary first molar teeth were divided into two main groups (n=20) according to the preparation designs: group B: (Butt joint) & group S (Shoulder finish line): and each group was subdivided into two subgroups (n=10) according to materials: group E: lithium disilicate glass-ceramic (IPS e.max CAD; Ivoclar Vivadent AG) & group C: hybrid nanoceramic (Cerasmart; GC Corp). A digital scan was made with a digital scanner (Identica Hybrid Scanner; Germany) and virtual endocrowns were milled with a 5-axis milling machine ((Imes-Icore; CORiTEC250i; Germany). The silicone replica technique and a stereomicroscope (25X) were used to measure the marginal and internal gaps of endocrowns at different points. All data were statistically analyzed using three-way ANOVA test with Post Hoc Tukey test to detect pair-wise comparison. Student's t-test also was used. Results: There was a statistically significant difference between the preparation designs on the marginal integrity and internal adaptation (p < 0.05), but restorative materials significantly affected on the internal adaptation (p < 0.05) and showed no significant effect on the marginal integrity (p>0.05). Conclusions: All tested groups showed acceptable marginal and internal gaps mean values. Butt joint design showed a better effect than shoulder finish line design on the marginal integrity and internal adaptation. Cerasmart showed a better effect than IPS e.max CAD on the internal adaptation.