Aim: consequentially to the development of CAD/CAM restorative dental materials, limited data regarding their survival rate and fracture strength is available when they are used as occlusal veneers. The aim of this study is to evaluate the influence of thermomechanical loading on fracture strength of minimally invasive occlusal veneer restorations fabricated from different CAD/CAM materials and bonded to human maxillary molars.
Methods: twenty extracted maxillary molars were assigned to two groups (n = 10). LS (zirconia-reinforced lithium silicate) (Celtra Duo, Dentsply Sirona), and PI (polymer-infiltrated ceramic) (Enamic, Vita). The teeth received a preparation for a conservative full-coverage occlusal veneer with a 1-mm cusp reduction with a marginal champfer. Restorations were obtained using the CEREC chair-side (CEREC MC X) and luted with a two-step self-etch adhesive system (Clearfil SE, Kuraray) and a dual resin cement (Variolink II, Ivoclar-Vivadent). After thermomechanical aging (240.000 cycles at 50 N with 5-55°C thermocycling), the specimens were loaded to fracture using a universal testing machine. The statistical analysis was made using one-way ANOVA and Tukey test.
Results: all specimens survived the fatigue test. PI showed a higher mean fracture load value (3409 ± 694 N) with statistically significant differences than LS (2352 ± 772 N).
Conclusion: PI showed the highest values of fracture resistance followed by LS favoring their use for occlusal veneers.
