In Vitro Shock Absorption Tests on Implant-Supported Crowns: Influence of Crown Materials and Luting Agents

Purpose: To investigate the force absorption capacity of implant-supported crowns made of different restorative materials and connected to abutments with different luting agents. Materials and Methods: Molar crowns were milled of different computer-aided design/computer-aided manufacture materials (n = 8 crowns per material): polymethyl methacrylate, polyether ether ketone, composite, lithium disilicate, titanium, and zirconia. Crowns were mounted on titanium implant replicas using different luting agents: uncemented, temporarily cemented (zinc oxide-eugenol cement), conventionally cemented (zinc oxide phosphate cement), and adhesively bonded. As a reference, one implant replica was tested without a crown. Force absorptions of the different combinations of crown materials and luting agents were determined by applying an increasing force (0 to 250 N) on the occlusal crown surface and measuring the resulting force below the implant. Mean curves of applied and resulting forces up to 200 N were determined (six measurements per group), and slopes were calculated. Statistical analysis was performed (one-way analysis of variance, Bonferroni post hoc test, α = .05). Results: Significant (P .001) differences in the applied and resulting forces were found between the crown materials that were uncemented, temporarily cemented, cemented, and adhesively bonded. Materials with higher moduli of elasticity (ceramics, titanium) showed steeper slopes of the force curves and lower shock-absorbing capacity than resin-based materials, but were influenced more by the luting agents. The damping effects of resin-based materials were higher in combination with all cementation and luting modes. Conclusion: Shock absorption tests exhibited a strong material-dependent damping behavior of implant-supported crowns. The shock-absorbing capacity of crown materials with high moduli of elasticity may benefit from conventional cementation. Keywords: CAD/CAM, crown, implant, luting agent, resin-based materials, shock absorption