Stress-Absorbing Effect of Restorative Materials on Implant-bone Model

Adequate bone response after implant placement is that of remodeling with gradual functional adaptation to occlusal stress. Conversely, overstressing the implant causes bone absorption.We should perform prosthetic management so that adequate occlusal stress can be generatedon the implant. We designed a new implant-bone model made from urethane foam as cancellousbone and acrylic resin as cortical bone. An Apaceram implant was placed in the center of themodel. Seven superstructures were fabricated from the following materials: complete alloy (AL), complete hard resin (HR), complete polycarbonate (PC), hard resin-veneered (HV), polycarbonate-veneered (CV), porcelain-veneered (PV), and Biotron R 70-lined (BL). A small accelerometerwas attached to the abutment and two strain gauges were placed on the surface of the model.A metal rod with an accelerometer was dropped on the superstructure. Stress-absorbing effect ofthe materials was evaluated by four signals. Results: 1. Abutment acceleration of BL was the lowest of all specimens. The accelerations of BL, PC, HR, CV, and HV decreased in this order by about 70-80% when compared to that of AL. Theacceleration of PV was almost the same as that of AL. 2. Rod accelerations of PC, HR, CV, and HV decreased in this order by about 70-80% whencompared to that of AL. Rod accelerations of PV and BL were almost the same as that of AL. 3. Influence on strains of the model surface was lower than that on the acceleration. Strainsof BL decreased by about 20% the lowest of all specimens. Strain increased because the loading sitewas close to the strain gauge. 4. The superstructure lined with Biotron R 70 seemed to show the highest shock-absorbingeffect of all samples.