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).
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).
The screw access hole decreased the fracture resistance. A
surrounding zirconia wall for the screw access hole increased the
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