Fracture resistance of thin occlusal veneers made from hybrid ceramic (Cerasmart) -In vitro study

Document Type : Original Article

Authors

1 Master Candidate, Department of Fixed Prosthodontics, Faculty of dentistry, Cairo University, Egypt.

2 Professor of Fixed Prosthodontics, Faculty of dentistry, Cairo University, Egypt.

Abstract

Statement of the problem: Occlusal veneers represent a conservative alternative to traditional restoration for restoring tooth wear. However, the ability of occlusal veneers with thin (reduced) thickness using hybrid ceramics to withstand masticatory forces in the posterior area is not yet known. Purpose: the purpose of this in vitro study was to evaluate the fracture resistance of thin occlusal veneers made from hybrid ceramic (Cerasmart). Materials and methods: Twelve human first maxillary molars were used in this study collected from patients with untreatable periodontal problems (grade III mobility); Teeth were chosen to be free from any caries, defects or Cracks. (n= 12) Teeth were prepared to receive Cerasmart occlusal Veneers with 1.8 mm thickness at the cusp tip and 1.2 mm at the central groove. A standardized tooth preparation was applied to all specimens using CNC milling machine, with anatomical occlusal surface preparation with 1 mm ferrule and 1mm deep chamfer finish line. Then occlusal veneers were fabricated by CAD/CAM milling using The CEREC AC system. Then all occlusal veneers were checked over their corresponding teeth for Seating. Then cementation using Re1yXTM Unicem (dual cure self-adhesive resin cement). All samples were subjected to thermo-cycling for 1000 cycle, and cyclic loading for 25,000 cycles. The samples testing was done by compressive mode using a universal test machine along the long axis of the occlusal veneers using load applicator in the form of metallic rod with rounded end (5 mm diameter). Data were collected, tabulated and statistically analyzed. RESULTS: The mean values and standard deviation of fracture resistance (N) measured by fracture resistance test as a function of restoration thickness. It was found that occlusal veneers with a thickness of 1.2 and 1.8 mm recorded fracture resistance mean value (1743.7± 387N). CONCLUSIONS: Within the limitations of present in vitro study, Hybrid ceramic thin occlusal veneers with a thickness of (1.2 and 1.8 mm) can withstand the masticatory forces in the posterior area, which providing a conservative treatment for tooth wear.

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