In vitro comparison of bonding to zirconia- or glass- based ceramics between flowable resin composites and composite resin cements.

Purpose: To evaluate and compare the bonding of flowable resin composites and light-cured resin cements to dental ceramics.

Methods: Grit-blasted zirconia plates were primed with MDP-containing adhesive. Lithium disilicate glasses plates were etched with HF and primed with silane. Two flowable resin composites with high (CM: 75 wt%/62 vol%) and low (BF: 67.3 wt%/47 vol%) filler contents, and two resin cements, again with high (C: 72 wt%/69 vol%) and low (R: 66 wt%/47 vol%) filler contents, were bonded to both types of pretreated ceramics. Shear bond strength (SBS) was measured after 24 hours water storage or 10,000 times thermocycling between 5 and 55°C. The viscosities and film thicknesses of the four resin-based luting agents (RBLAs) were also explored by rotational rheometer and metallurgical microscope severally.

Results: Different RBLAs provided statistically different SBS values, with the high-filler specimens exhibiting higher SBS values than the low-filler specimens. The viscosities decreased in the order C > R > BF > CM. The film thicknesses for the BF and C groups were higher than those of the CM and R groups.

Clinical significance: This study provides evidence that flowable resin composites with high filler contents and low viscosities may serve as an alternative to light-cured resin cements for luting zirconia or lithium disilicate glass. This expands the range of light-cured luting agents available for bonding of veneers or other thin restorations, which is of great benefit to clinical practice.