Effect of primary versus secondary splinting impression techniques on the passive fit of screw-retained implant prosthesis: a randomized clinical trial

Abstract

Abstract Background The utilization of splinting techniques for impression copings is commonly advised for complex implant-supported prostheses, as it can enhance the fit of these prostheses. However, there is limited understanding regarding the impact of the secondary splinting of implant analogues, on the passive fit of the prostheses. Limited data are available on the secondary splinting of implant analogues before pouring the impression and its comparison with the primary technique of intraoral splinting of impression copings prior to impression making. Objectives This study's objective was to determine the impact of the primary versus secondary impression splinting techniques using resin on the passive fit of screw-retained prosthesis. Material and methods This randomized clinical trial (RCT) involved two parallel groups consisting of 14 completely edentulous patients, with seven patients in each group. Each patient received a total of eight implants, four implants per arch, resulting in a total of 28 screw-retained prostheses. Two different impression splinting techniques were employed. Group (1) utilized the primary splinting technique, where the impression copings were splinted before taking the impression. In contrast, Group (2) utilized the secondary splinting technique, where the implant analogues were splinted before pouring the impression material. To evaluate the passivity of the screw-retained prostheses in both groups, a single-screw test (one-screw test) was used. Additionally, supplementary methods, including the screw resistance test, were employed. Results The findings of this RCT revealed higher passivity scores for secondary splinting impression pouring technique with a statistically significant difference ( P = 0.082). There was a 2.2-fold greater frequency of non-passivity in the primary splinted method. In group (2), the likelihood of non-passivity was four times higher for upper arches prostheses, while there was no significant difference ( P = 0.5) observed in both groups for lower arches prostheses. Conclusions The study found that using the secondary splinting impression pouring technique resulted in greater passivity of the implant prostheses compared to the primary splinting impression technique.