Abolfazl Saboury1, Minoo Mahshid1, Farhad Tabatabaian1, Leila Moghadam2. 1. Department of Prosthodontics, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2. Department of Prosthodontics, School of Dentistry, Semnan University of Medical Sciences, Semnan, Iran.
Abstract
OBJECTIVE: To evaluate the effect of screw access hole design on the fracture resistance of cement-retained implant-supported zirconia-based restorations with screw access holes. MATERIALS AND METHODS: Thirty cement-retained implant-supported zirconia-based molar crown specimens were fabricated. The specimens were divided into 3 groups of 10: without access holes (C), with screw access holes (S), and with screw access holes accompanied with a surrounding zirconia wall (W). The veneering ceramic thickness was 0.8 mm in all groups. Implants were vertically mounted in a metal block. Abutments were screwed on the implants and the specimens were cemented to the abutments. A universal testing machine applied compressive forces to the specimens until fracture. Fracture resistance values of the specimens were measured. One-way analysis of variance (ANOVA) and Tukey HSD tests were used to analyze data (P < .05). RESULTS: The mean fracture resistance values were 5794.85 N for C, 2691.48 N for S, and 3878.06 N for W. The screw access hole design significantly affected the fracture resistance (P < .0001). Significant differences were found between C and S (P < .001), C and W (P < .001), and S and W (P = .026). CONCLUSIONS: The screw access hole decreased the fracture resistance. A surrounding zirconia wall for the screw access hole increased the fracture resistance. CLINICAL SIGNIFICANCE: Screw access hole design may affect the fracture resistance of cement-retained implant-supported zirconia-based restorations with screw access holes. This study introduced a screw access hole design to improve the fracture resistance of these restorations.
OBJECTIVE: To evaluate the effect of screw access hole design on the fracture resistance of cement-retained implant-supported zirconia-based restorations with screw access holes. MATERIALS AND METHODS: Thirty cement-retained implant-supported zirconia-based molar crown specimens were fabricated. The specimens were divided into 3 groups of 10: without access holes (C), with screw access holes (S), and with screw access holes accompanied with a surrounding zirconia wall (W). The veneering ceramic thickness was 0.8 mm in all groups. Implants were vertically mounted in a metal block. Abutments were screwed on the implants and the specimens were cemented to the abutments. A universal testing machine applied compressive forces to the specimens until fracture. Fracture resistance values of the specimens were measured. One-way analysis of variance (ANOVA) and Tukey HSD tests were used to analyze data (P < .05). RESULTS: The mean fracture resistance values were 5794.85 N for C, 2691.48 N for S, and 3878.06 N for W. The screw access hole design significantly affected the fracture resistance (P < .0001). Significant differences were found between C and S (P < .001), C and W (P < .001), and S and W (P = .026). CONCLUSIONS: The screw access hole decreased the fracture resistance. A surrounding zirconia wall for the screw access hole increased the fracture resistance. CLINICAL SIGNIFICANCE: Screw access hole design may affect the fracture resistance of cement-retained implant-supported zirconia-based restorations with screw access holes. This study introduced a screw access hole design to improve the fracture resistance of these restorations.