Effect on the Fracture Resistance of Monolithic Zirconia Custom Abutment in Different Angulation: An In Vitro Study

The study was designed to find out the effect of different angulations of monolithic Zirconia custom-made abutments on fracture resistance. In this experimental type in vitro study, a total of thirty implant analogs with a diameter of 4.3 mm and a length of 11.5 mm were obtained for the maxillary central incisor. A total of thirty abutments specimens in three groups- 0-degree, 15-degree, and 25-degree, ten in each group were fabricated with monolithic zirconium by CAD/CAM system. Each abutment was subjected to load until fracture in a Universal testing machine and data was collected to a data collection sheet. One-way ANOVA was done to compare the fracture load among the three groups and pairwise comparison was done by Tukey post hoc test. The statistical significance p-value was considered as less than 0.05. The range of fracture load of 0-degree, 15-degree, and 25-degree angulated abutments were 590.55-1305.43N, 755.89-1720.55N, and 496.68-820.88N respectively. The highest fracture resistance was shown in 15-degree angulated custom-made zirconium abutments with a mean ± SD of 1223.442 ± 317.771N and the lowest fracture resistance was shown in case 25-degree with a mean ± SD deviation of 653.139 ± 102.045N. The mean ± SD of the 0-degree abutment was 948.944±245.588N. 95% Confidence interval of the mean were 773.260-1124.627N, 996.122-1450.761N, and 580.140-726.137N were assessed in cases of 0-degree, 15-degree, and 25-degree respectively. The fracture load or fracture resistance among the three groups of custom-made monolithic zirconium abutments were significantly different. 15-degree angulated abutment had higher fracture resistance properties. straight abutment had more fracture resistance properties than that of 25-degree abutments, but less than 25-degree abutments.