In vitro evaluation of the fracture load of CAD/CAM made zirconia crowns in primary teeth: Comparison of two different cement types and spacings

Objective: The aim of this study is to evaluate the effect of different adhesive cements on the fracture strenghts of zirconia crowns obtained using the computer aided design/ computer aided manufacturing (CAD/CAM) system in primary molars at different cement intervals under in vitro conditions. Method: A total of forty extracted primary second molars were divided into four groups, each containing 10 teeth. Prepared teeth were embedded in acrylic blocks. Crowns were fabricated with computer aided design/computer aided manufacturing (CAD/CAM) system at 100 µm and 200 µm cement spacing. Each cement spacing group was further divided into two equal subgroups for cementation with glass ionomer cement and adhesive resin cement (n=10). After cementation, samples were stored in distilled water until fracture testing. Universal testing machine applied a load at a crosshead speed of 10 mm/min. The fracture load of each specimen was measured and recorded in Newtons (N). The statistical analysis of the obtained data was performed using the NCSS (Number Cruncher Statistical System) 2007 Statistical Software package program (Utah, USA). Results: It was observed that the different cements and cement spacing did not have a statistically significant effect on the fracture strength of zirconia crowns (p>0.05). The highest mean fracture load value was observed in the group where adhesive resin cement was used at a 100 µm cement spacing. Conclusion: Within the limitations of this study, it can be stated that the fracture resistance values of CAD/CAM zirconia crowns applied to primary teeth are high. The values of the applied cement spacings and the cements can be used as alternatives to each other. Keywords: Fracture strength, monolithic zirconia crown, cement spacing, cement, CAD/CAM.