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The aim of this invitro study was to evaluate the fracture resistance of endodontically treated canines restored with one-piece milled zirconia post and core in the varying ferrule modes. Fifty recently extracted human maxillary canines were endodontically treated and randomly divided into 5 groups of 10 specimens each. According to the defect degree of ferrule, intact ferrule was classified as group A and served as control, 2 mm ferrule height without buccal ferrule was classified as group B, 2 mm ferrule height without mesial and buccal ferrule was classified as group C, 2 mm ferrule height without mesial, buccal and lingual ferrule was classified as group D, no ferrule preparation was classified as group E. All of the teeth were restored with one-piece milled zirconia post and core, and zirconia crowns. The teeth were prepared to standardized specifications. The restored teeth were loaded to fracture at a 135° angle to their long axis, at a cross-head speed 0.5 mm/min, and the load (N) at failure was recorded. Statistical analysis was performed by SNK pairwise multiple comparisons (α=0.05). The mean fracture resistance of five groups as follows: 1019.30±139.01N for group A, 861.20±105.67N for group B, 833.70±100.56N for group C, 733.20±96.91N for group D, 698.00±99.90N for group E. The fracture resistance of restored teeth between group B and group C, group D and group E had no statistically significant difference(P>0.05). The fracture resistance of the rest pairwise group comparisons had statistically significant difference(P |
