Effect of Different Filler Loading on Fracture Resistance of CAD/CAM Resin Composite restoration in Premolar Teeth: An In vitro Study

Document Type : Original Article

Authors

1 Ass. Professor of Conservative Dentistry, Faculty of Dentistry, Cairo University

2 Lecturer of Conservative Dentistry, Faculty of Dentistry, Cairo University

3 Lecturer of Fixed Prosthodontic, Faculty of Dentistry, Fayoum University

4 DDS of Fixed Prosthodontic, Faculty of Dentistry, AlAzhar University

Abstract

Objective: to assess the effect of different filler loading on the fracture resistance of CAD/CAM composite inlays when restoring MOD cavity in premolar teeth.
Materials and methods: A two type of CAD/CAM resin composite block with different amount of filler loading were used in this study as the follow: Grandio Bloc with high filler loading (HFL) about 86% filler and BRILLIANT Crios with low filler loading (LFL) about 70% filler. A 40 maxillary premolar were divided equally into four main groups (10 teeth each); a positive control group of unprepared teeth and a negative control group with prepared and unrestored MOD cavity. While the two other restored groups in which teeth with prepared MOD cavities were restored either with the high filler loading Grandio Bloc CAD/CAM resin composite inlay or low filler loading BRILLIANT CAD/CAM resin composite blocks. A standardized MOD cavity were prepared in premolar teeth using the inlay preparation kit. working and master models were fabricated. A new restoration was created in the Cerec in-lab software version. The restoration were processed and cemented in place using Dual-link universal Resin cement. All specimen groups (positive control, negative control and restored groups) were tested for fracture resistance using universal testing machine. Fractured teeth were examined with USB digital microscope at 25X magnification. Two-way ANOVA (Analysis of Variance) was used to compare between groups. Tukey’s post-hoc test was used for pair-wise comparison between the mean when ANOVA value were significant. The significance level was set at P≤0.005.
Results: There was no statistical significant difference between the intact teeth group and HFL GRANDIO inlays and LFL BRIILIANT CRIOS. However there were statistically significant between prepared but not filled teeth groups and all other groups. The HFL GRANDIO inlays restored teeth group recorded high mean value than LFL BRIILIANT CRIOS but without statistically significant difference between them. A mixed type of failure was detected; cohesive failure either within tooth and restoration and adhesive failure along cement line. Conclusions: the proper balance between filler and polymer matrix was able to improve the mechanical performance of resin composite blocks despite amount of filler loading. The use of CAD/CAM resin composite could be considered a perfect choice in the restoration of badly broken vital posterior teeth.