Load to failure of high-density polymers for implant-supported fixed, cantilevered prostheses with titanium bases

To analyze the load to failure of different CAD/CAM high-density polymers (HDPs) and zirconia when titanium (Ti) bases were included in a cantilevered situation.

Five specimens were fabricated from five different CAD/CAM polymethyl methacrylate (PMMA) HDPs (Copratemp [CT]; Tempo-CAD [TC]; TD Dental [TD]; M-PM Disc-Pink [MPM]; M-PM Disc-White [MPMW]), and five specimens were prepared from a 3Y-TZP zirconia (FireZr [FZR]) (control). Ti bases (D Master Dental Implants) were cemented onto the specimens (8 mm [thickness] × 7 mm [width] × 30 mm [length]). Each specimen was fixated using a clamp for a cantilever loading distance of 10 mm. The load was applied on the cantilever until failure, and the maximum load to failure values (N) were analyzed by using analysis of variance (GLIMMIX procedure) with a lognormal error distribution in addition to the restricted maximum likelihood estimation method to eliminate the need for equality of variances and Tukey Honest Significant Difference (α = .05).

Differences among load-to-failure values of HDPs were not significant (P > .05). However, zirconia had significantly higher load-to-failure values than HDPs (P < .001). The behavior of HDPs and zirconia under loading was different in terms of displacement. HDPs showed weaker but more ductile behavior than zirconia, which is stronger, but more brittle.

Tested brands of HDPs performed similarly under loading. Zirconia with a Ti base showed higher strength compared to all tested HDPs with a Ti base. The loads that fractured the specimens with Ti bases were close to the maximum occlusal bite forces recorded in previous clinical studies.