objective: to compare the effect of abutments' proximal wall thickness adjacent to the connector on the fracture resistance of a three-unit fixed partial denture framework.
Materials and methods: twenty-eight FPD frameworks were divided into 4 groups according to the finish line thickness on the proximal wall adjacent to the connector (n=7): 0.4 (group I); 0.8 (group II); 1.0 (group III) and 1.2 mm (group IV). Preparations were scanned using EXOCAD software. Using Stereo-lithography technology, 3D resin models were printed simulating the maxillary left quadrant with missing tooth number 25 and prepared teeth 24 and 26 to receive a three-unit FPD.
All FPD frameworks with different proximal wall thicknesses were cemented to the models and subjected to thermal cycling corresponding to 10 months of clinical service
Specimens were tested for fracture resistance in a universal testing machine until failure. Mode of failure was recorded for each specimen and visually investigated. Results were recorded, tabulated, and statistically analyzed.
Normality tests were considered to evaluate the normality of data distributions. One-way ANOVA followed by Tukey's post hoc analysis tests was conducted to analyze the fracture resistance significant difference.
Results: Descriptive analysis showed a greater mean value for Group IV (1191.9) followed by Group III (789.4), group II (702.3), and Group I (511.8) consecutively. One-way ANOVA revealed that there was a statistically significant difference between the four groups that were represented by (P<0.001).
Conclusions: Modifying the proximal finish line thickness adjacent to the connector affected the fracture resistance of the three-unit Zirconia FPD framework.