Wear behavior of current computer-aided design and computer-aided manufacturing composites and reinforced high performance polymers: An in vitro study.

OBJECTIVE: To analyze the wear rate of computer-aided design and computer-aided manufacturing (CAD/CAM) composites, polyetheretherketones and glass ceramics. MATERIAL AND METHODS: Our study groups were prepared from two different resin-based composites (Brillant Crios, Cerasmart), a glass ceramic (IPS Emax CAD) and reinforced polyetheretherketone (BioHPP) material (n = 10). Premolar teeth were used as antagonists. The specimens, which were subjected to two body wear tests (240,000 cycles, 1.2 Hz, 50N) in the chewing simulator, were scanned with a 3D laser scanner both before and after the wear test. Volume loss and wear depth were determined by means of the obtained images software program. The wear pattern was examined by scanning electron microscopy. Kruskal Wallis test served for analyzing. RESULTS: The least volume loss and wear depth were seen in the polyetheretherketone material (0.06 ± 0.04 mm3 , 0.02 ± 0.01 mm), while the maximum volume loss was seen in the groups containing resin-based composite. (p = 0.05). The volume loss value in glass ceramics is between CAD/CAM composites and polyetheretherketone. CONCLUSION: The behavior of polyetheretherketone against enamel was different from glass ceramics and composite materials in terms of the amount of wear. CLINICAL SIGNIFICANCE: Polyetheretheketone can be considered as an alternative to other chairside materials in terms of wear resistance.

Can Fiber Application Affect the Fracture Strength of Endodontically Treated Teeth Restored with a Low Viscosity Bulk-Fill Composite?

OBJECTIVE: The aim of this study is to evaluate the effects of different fiber insertion techniques and thermomechanical aging on the fracture resistance of endodontically treated mandibular premolar teeth restored using bulk-fill composites. MATERIALS AND METHODS: Eighty human mandibular premolar teeth were randomly divided into eight groups: Group IN, Group BF, Group PRF1, Group PRF2, Group IN-TMA, Group BF-TMA, Group PRF1-TMA ,and Group PRF2-TMA. Group IN (intact) and Group IN-TMA (intact but subjected to thermomechanical aging) served as control groups. In the other six groups, endodontic treatment was performed and standardized mesio-occluso-distal (MOD) cavities were prepared. In BF, PRF1, and PRF2, the cavities were restored with bulk-fill composite only, bulk-fill/Ribbond, and bulk-fill/additional Ribbond, respectively. In BF-TMA, PRF1-TMA, and PRF2-TMA, the teeth were subjected to thermomechanical aging after the restorations. All of the teeth were fractured on the universal testing machine. Fracture surfaces were analyzed with a stereomicroscope. RESULTS: Control groups showed significantly higher fracture strengths than tested groups (P<0.05). No statistically significant difference was observed among the tested groups (P>0.05). Most of the favorable fractures were seen in PRF1, PRF2, and PRF2-TMA. Most of the unfavorable fractures were seen in BF-TMA. CONCLUSIONS: Although fiber insertion with different techniques did not increase the fracture strength of teeth restored with bulk-fill composites, it increased the favorable fracture modes. Thermomechanical aging did not change the fracture strength of the groups.