Evaluation of Vertical Misfit and Torque Loss of Different Abutments for Tri-Channel Type Internal Connection Dental Implants After Mechanical Cycling

The aim of this study was to evaluate the mechanical behavior of UCLA and Mini-conical abutments for implants with Tri-channel connections regarding torque loss and vertical misfit. Twenty 3-element metal-ceramic fixed partial dentures (FPD) supported by 2 implants were manufactured and divided into 2 groups (n = 10): UCLA (group 1) and Mini-conical Abutments (group 2). The evaluation of torque loss was carried out before and after mechanical cycling, while the vertical fit was evaluated throughout the different stages of manufacturing the prostheses, as well pre- and postcycling (300,000 cycles, 30 N). Statistical analyses of torque loss and vertical misfit were performed using the linear mixed effects model. Both groups showed torque loss after mechanical cycling (P < .05); however, there was no significant percentage differences between them (P = .795). Before cycling, the groups showed a significant difference in terms of vertical misfit values (P < .05); however, this difference was no long observed after cycling (P = .894). Both groups showed torque loss after the cycling test, with no significant difference (P > .05). There was no significant difference in vertical misfit after mechanical cycling; however, in group 1 (UCLA) there was accommodation of the implant-UCLA abutment interface, while group 2 (Mini-conical abutment) did not show changes in the interface with the implant after the test. Both groups behaved similarly regarding the torque loss of the prosthesis retention screws pre- and postmechanical cycling, with greater loss after the test.

Bone level changes around platform switching and platform matching implants: a systematic review with meta-analysis

The amount of marginal bone loss is considered an important criterion to evaluate the implant therapy outcome and to predict the prognosis of the implant rehabilitation. The purpose of this systematic review was to examine the available literature comparing clinical and radiological outcomes like the implant failure rates and marginal bone loss around platform switching dental implants versus platform matching ones. English randomized controlled human clinical trials, comparing one or more PS groups with one or more PM groups, with at least 12 months of follow-up after loading and 10 implants, providing carefully the number of PS- and PM- implants used as well as implant survival and data concerning bone level changes or marginal bone loss around implants, were included. Fifteen publications, involving a total of 1439 implants and 642 patients, were eligible. More studies showed less mean marginal bone loss around PS implants and none of them showed differences in terms of implant failure rates. This review confirmed a great effectiveness of platform switching technique to prevent marginal bone resorption. Nevertheless, this result should be interpreted cautiously because of the heterogeneity of the included studies.