Abstract
Objective: To evaluate marginal fit and internal adaptation of three-unit Zr frameworks fabricated from four Zr CAD/CAM milling systems.
Methods: Fixed partial denture models were replicated (40 stone models) using Polyvinyl Siloxane impression material (PVS) and type IV stone for Zr framework fabrication. FPDs were milled with four CAD/CAM systems, Group-II: LAVA (TM) Zirconia milled by LAVA (TM), Group-2: Vita In-Ceram YZ milled by Cerec (R), Group-3: Zirconia milled by GM1000 and Group-4: Zirconia milled by DWX-50N. Twelve marginal gap measurements per framework were performed at pre-established points, with a metallurgical microscope (Zeiss, Germany) at 500X magnification. Eight measurements of cement space per section were performed for adaptation. Data was analyzed using ANOVA and Tukey post hoc test.
Results: Zirconia FPD frameworks exhibited gaps ranging from 16 to 50.1 mu m for marginal fit and 26.8 to 102.5 mu m for internal adaptation. Group-3 [20.8 (8.3) mu m & 50.3 (11.4) mu m] and Group-4 [16.0 (4.0) mu m & 40.2 (8.8) mu m] specimens showed significantly lower marginal fit and internal adaptation gaps compared to Group-I [50.1 (13.4) mu m & 100.5 (16.7) mu m] and Group-2 [38.9 (8.2) mu m & 102.5 (13.4) mu m] specimens respectively.
Conclusions: Different CAD-CAM systems for fabrication of Zr FPD frameworks displayed a significant influence on marginal fit and internal adaptation of restorations.