Prosthetic design and restorative material effect on the biomechanical behavior of dental implants: strain gauge analysis

Abstract

Objective: The purpose of this in vitro study was to evaluate the effect of different implant prosthetic designswith two restorative materials on biomechanical behaviour using strain gauge analysis. Material and Methods:6 different screw-retained implant restorations were designed and fabricated using a CAD/CAM system. Theseimplants were divided into three main groups according to each design: group FB (fixed bridge); CB (cantileverbridge); SC (separate crowns). Each group was divided into two subgroups according to their restorativematerial: subgroup I – ultra translucent multi-layered zirconia (Kuraray Noritake Dental Inc, Japan); subgroupII – a combination of PEEK framework (BioHPP, Bredent, GmbH & Co.KG, Germany) and zirconia crowns(ultra-translucent multi-layered zirconia, Kuraray Noritake Dental Inc, Japan). Each subgroup was subjected toa vertical load of 100 N and their biomechanical behaviour was evaluated using a strain gauge (Kyowa, Japan)with a resistance of 120 ohms, length of 1 mm and width of 2.4 mm. For the implants, two strain gauges werepositioned buccally and lingually, parallel to the long axis of the implant. For the restoration, two strain gaugeswere positioned buccally and lingually in the middle of it. The results were analyzed using three-way analysisof variance (ANOVA), followed by serial two-way and one-way ANOVAs at each level of the study, followed byTukey’s post hoc test P-values were adjusted for multiple comparisons using BENFORRONI correction and thesignificance level was set at P plus/minus 0.05 for all tests. Results: FB showed the lowest strain values out of all 3 designgroups. Moreover, the combination of PEEK and zirconia showed strain values smaller than full zirconia. Thehighest mean strain value was recorded in CB at 299.50 while the lowest mean strain peak value was recorded ingroup FB (74.50). The highest strain peak was recorded in CB subgroup I (3901.0 plus/minus 195.91) and the differencehad statistical significance (P-value < 0.01). Conclusion: the fixed bridge designed with PEEK framework andzirconia crowns was found to be more favorable in restoring the posterior edentulous area regarding strainmeasurements on the level of prosthetic components, implant and bone level.KEYWORDSBiomechanics; Dental implants; CAD/CAM; Dental prosthesis; Milling machines.