Comparison of Peri-implant Strain on Loading, between Splinted, Nonsplinted, Cement-retained and Screw-retained Implant-supported Prostheses: An In Vitro Study

Background and objectives: The present <i>in vitro</i> study was done to measure and compare peri-implant strain generated by different types of prostheses, namely, cement-retained splinted, cement-retained nonsplinted, screw-retained splinted and screw-retained nonsplinted with the help of strain gauges in polyurethane mandibular model under loading. Materials and methods: Implants were placed in two polyurethane mandibular models in first and second molar regions. Four different types of prostheses were made. Cement-retained splinted and cement-retained nonsplinted prostheses were fabricated on one model. Screw-retained splinted and screw-retained nonsplinted are fabricated on another model. Strain gauges are attached on the buccal and lingual sides of each implant. Metal jigs were fabricated for simultaneous load application during vertical and oblique loading. A static load of 400 N was applied to the central fossae region of both molars using the universal testing machine to test vertical loading. The load was applied at 30° to the crown to test oblique loading. For every model, a load was applied 15 times, and the peri-implant strain was recorded. Results: On vertical loading, the mean peri-implant strain (±SD) generated was found to be highest in nonsplinted screw-retained (1211.50 ± 65.28 microstrains and 1009.1 ± 42.06 macrostrains) and least in splinted cement-retained (630.70 ± 31.98 microstrains and 519.60 ± 32.48 microstrains) in the first molar region and second molar region, respectively. On oblique loading, the mean peri-implant strain (±SD) generated was found to be highest in nonsplinted screw-retained (702.47 ± 31.47 microstrains and 565.00 ± 16.11 microstrains) and least in splinted cement-retained (396.33 ± 27.04 microstrains and 302.47 ± 36.19 microstrains) in both 1st and 2nd molars, respectively. Conclusion: Splinted crowns produce less peri-implant strain when compared with nonsplinted crowns. Cement-retained prosthesis produces less strain when compared with screw-retained prosthesis. The least peri-implant strain was observed in splinted cement-retained crowns.