Marginal Fit and Resistance of Heat Pressed Glass Ceramic Restoration to Fracture with Different Preparation Designs for Occlusal Veneer

Authors

1 Dentist at Egyptian Ministry of Health, Cairo, Egypt

2 Professor of Crowns and Bridges, Faculty of Dental Medicine for Girls, Al-Azhar University, Cairo, Egypt

3 Lecturer of Crowns and Bridges, Faculty of Dental Medicine for Girls, Al-Azhar University, Cairo, Egypt

Abstract

Purpose: to assess the influence of preparation design on marginal fit and fracture resistance of pressable fabricated occlusal glass ceramic veneers. Materials and Methods: Two master preparations, one of the traditional planar design and the other of the modified one, were designed and fabricated by printing on two maxillary first bicuspids. The preparations received an occlusal veneer preparation and a finish line of circumferential-chamfer type. Each prepared design was duplicated 20 times to form 20 epoxy resin replicas ["n=20" dies for conventional planner design (C) group and "n=20" dies for proposed modified design (M) group]. Each group was further subdivided into two subgroups (n=10) based on the material; IPS e.max press (EP) and Vita Ambria press (VA). Stereomicroscope was used to measure the vertical marginal gap distance. Fracture resistance test was conducted using universal testing machine. Data was tabulated and statistics was used to analyze it. Examination and detection of the mode of failure of the fractured samples were also determined. Results: IPS e.max press with proposed modified design recorded the least value for the vertical marginal gap distance (60.28±6.95μm), while Vita Ambria with conventional planner design recorded the highest mean value of vertical marginal gap distance (98.33±6.77μm). Vita Ambria with conventional planner design recorded the highest mean value of failure load (787.96±212.54N), while Vita Ambria with proposed modified design recorded the lowest mean value of failure load (644.34±166.67N). Conclusion: Preparation designs and materials marginal gap were within acceptable range. However, neither the design of the preparation nor the material type have affected the resistance of fracture.

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