Effect of Different Preparation Designs on the Fracture Load of Two Machinable Laminate Veneers

Aim: The present study was performed to evaluate the effect of different preparation designs [window, butt- Joint, and incisal overlap], on the fracture load of two CAD / CAM laminate veneer materials [Zirconia CAD / CAM and resinnanoceramic ; lava ultimate].Materials and Methods: Thirty maxillary anterior teeth were restored with ceramic laminate veneers and divided into 6 groups as follows: group I-A (laminates made of Ultra translucent zirconia CAD with window preparation design), group I-B (laminates made of Ultra translucent zirconia CAD with butt-joint preparation design), group I-C (laminates made of Ultra translucent zirconia CAD with incisal overlap preparation design), group II-A (laminates made of Lava ultimate (Resin nano ceramic) CAD with window preparation design), group II-B (laminates made of Lava ultimate CAD with butt-joint preparation design), group II-C (laminates made of Lava ultimate CAD with incisal overlap preparation design). Fracture load test was performed using the Universal Testing Machine (UTM). Data were statistically analyzed using One-way analysis of variance ANOVA followed by Tukey’s multiple comparisontest. The results of the fracture load test were recorded in Newton: (I-A: 288.08N);(I-B: 322.47N); (I-C: 365.38N); (II-A: 301.15N); (II-B: 324.94N); (II-C: 394.95N). The results of the current study showed that there was no statistically significant difference between the means of fracture load for window, butt-joint and incisal overlap preparation designs among zirconia material. While, there was statistically highly significant difference between the means of fracture load for window, butt-joint and incisal overlap preparation designs among Lava ultimate material. The mean of fracture load for incisal over-lap preparation design was the highest, followed by butt-joint and window designs. Nonetheless, there were no statistically significant differences between translucent zirconia and lava ultimate regarding the fracture loadamong window, butt-joint and incisal overlap preparation designs.