الفهرس | Only 14 pages are availabe for public view |
Abstract Summary Replacing the missing teeth with implant-supported fixed dental prostheses became the standard of care in dental medicine in the past few decades. Failure of posterior implant-retained fixed partial denture is commonly associated with high occlusal overload. The aim of this in vitro study was to evaluate the stress distribution in implant supported screw-retained fixed partial posterior bridge, constructed from CAD/CAM Polyetheretherketone and Zirconia. A resin working model was constructed and two implants were placed parallel to each other using a surgical guide at the position of the mandibular second premolar and second molar. Ten 3 units implant supported screw-retained fixed partial posterior bridges were manufactured by the CAD/CAM technique; PEEK (group A) and zirconia (group B), 5 in each group. The CAD/CAM bridges were cemented to their abutments using the DTK adhesive, then screwed to the implants. Eight strain gauge sensors were attached at the cervical region around each implant at four sides (mesially, distally, buccally, lingually). The microstrains of each strain gauge were measured and analyzed separately for each implant supported screwretained fixed partial bridge. The strain measurement were recorded in microstrain (με) unit from the multi-channel strain-meter during load application by a universal testing machine. Each bridge was subjected to 300 N of force that was applied at the mid pontic region where the employed cross-head speed was 1 mm/min. The results of the microstrains showed a statistically significant difference between both groups at each location of measurement. group A (PEEK) showed the highest levels of mean microstrains at all locations of the strain gauge sensors (mesially, distally, buccally, linugally around each implant) than group B (Zirconia). Summary 66 The mean microstrains (με) produced mesially to the second premolar by the PEEK fixed partial dentures (4274.4 ± 70.63) was higher than that produced by the zirconia (1340.2 ± 34.40) with statistical significant difference (p <0.001). The mean microstrains (με) produced distally to the second premolar by the PEEK (8187.4 ± 89.88) was higher than that produced by the zirconia (1797.6 ± 65.19) with statistical significant difference (p <0.001). The mean microstrains (με) produced buccally to the second premolar by the PEEK (1696.0 ± 58.34) was higher than that produced by the zirconia (771.2 ± 12.64) with statistical significant difference (p <0.001). The mean microstrains (με) produced lingually to the second premolar by the PEEK (3768.6 ± 51.63) was higher than that produced by the zirconia (1032.4 ± 19.86) with statistical significant difference (p <0.001). The mean microstrains (με) produced mesially to the second molar by the PEEK (7917.6 ± 112.0) was higher than that produced by the zirconia (2715.6 ± 84.33) with statistical significant difference (p <0.001). The mean microstrains (με) produced distally to the second molar by the PEEK (3710.4 ± 40.60) was higher than that produced by the zirconia (1989.0 ± 50.19) with statistical significant difference (p <0.001). The mean microstrains (με) produced buccally to the second molar by the PEEK (2315.0 ± 47.13) was higher than that produced by the zirconia (744.0 ± 32.12) with statistical significant difference (p <0.001). The mean microstrains (με) produced lingually to the second molar by the PEEK (1271.0 ± 14.85) was higher than that produced by the zirconia (430.0 ± 12.23) with statistical significant difference (p <0.001). According to the results of the current study, the hypothesis was rejected due to the overload bending moments generated by loading resilient superstructure materials. |