Zirconia versus cobalt chromium meshwork reinforcement of implant-assisted mandibular overdenture

Abstract

Introduction This work aimed at testing the mechanical behavior of non-metallic enforcement of an implant-assisted mandibular overdenture denture base with a zirconium meshwork and compared its behavior to that of cobalt chromium meshwork under fatigue cyclic loading and fracture resistance. Materials and Methods Thirty completely edentulous models in which 2 laboratory implant analogues were secured in the position of the teeth 33 and 43 with ball abutments were used, 10 overdentures of group I had cobalt-chromium meshwork reinforcement of 1mm thickness, group II had 10 overdentures reinforced with 0.5 mm zirconia framework, and group III had 10 dentures with 1 mm zirconia reinforcing framework, the 3 groups were subjected to fatigue cyclic loading and fracture testing. Results Group I did not show complete fracture, only cracks in the denture base. group II showed complete fracture of its samples, and only 6 samples of group III showed complete fracture with cracks in the remaining 4. There were significant differences between groups I and II, groups I and III, and groups II and III where the fracture load was significantly greatest for group I, followed by group III, and finally group II. Conclusion The Co-Cr meshworks provided the strongest reinforcement of the overdenture bases as compared to zirconia frameworks. The 1 mm thickness zirconia meshwork was more resistant to fracture than the 0.5 mm zirconia framework, but weaker than the Co-Cr framework, however, its recorded resistance to fatigue cyclic loading and fracture was thought to provide an acceptable clinical service lifetime.