Influence of different bar attachment materials on stress distribution around two interforaminal dental implants: an in vitro study

Abstract

Statement of problem: Metal free materials were developed to be used as alternatives to metal alloys for fabrication of bar attachments. As the attachment must provide favorable stress distribution around implants, studies evaluating the influence of metal-free materials compared to metal alloys on stress distribution around dental implants are needed. Aim: to compare the effect of three different bar materials on stress distribution around two interformainal implants. Material and methods: 18 epoxy models of edentulous mandibular arches were used in which two parallel implants were inserted bilaterally at the canine areas in each model. The models were then divided equally into three groups according to the material used for the bar fabrication. In group I, six bars were fabricated from cobalt chromium alloy, in group II, six bars were fabricated using CAD-CAM milled zirconia, and in group III, six bars were fabricated using CAD-CAM milled polyetheretherketone. A universal testing machine was used to apply bilateral loading on each bar and the microstrain developed around implants was recorded using strain gauges. Results: A statistically significant difference in strain values was observed between the three groups with the highest strain values recorded in the cobalt chromium bar group, followed by the zirconia bar group, while the lowest strain values were observed in the polyetheretherketone bar group (P=.001). Conclusions: Metal free materials used for bar construction appear to be promising alternatives to cobalt chromium as they show a more favorable stress distribution, which positively affects the survival rate of implants.