The effect of space setting values and restorative block materials on the bonding of metal-free CAD/CAM onlay restorations

The effects of space setting values and restorative materials on the bonding of metal-free CAD/CAM onlay restoration were examined quantitatively and qualitatively. Seventy-two standardized MODB onlay cavities, prepared using human molars were restored under nine conditions, based on three space setting values, Increased (IC), Standard (SC, control), Decreased (DC), and three restorative block materials, resin-composites (RC), lithium disilicate glass-ceramics (LD), Feldspar ceramics (FC, control). All the restored specimens were subjected to cyclic loading and thereafter the microtensile bond strength (µ-TBS) was measured and analyzed statistically. The effect of space setting value on the µ-TBS varied with the restorative material. The bonding reliability of RC and the bonding durability of LD were significantly superior to FC. The bonding characteristics of RC under IC and DC were similar to those under SC. LD under DC and FC under IC were effective in obtaining an excellent bonding reliability relative to their SC.