Does Shelf preparation have an efficacy on primary stability of 4 implants supporting screw-retained full arch fixed dental prosthesis ?

Background

Four implant-supported fixed denture treatment concepts allow patients to receive immediate full-arched fixed prosthesis with esthetically and functionally pleased outcomes. To ensure primary stability, Resonance Frequency Analyses (RFA) values and insertion torques (IT) are essential factors. Bone reduction and shelf preparation are often needed to create maximum space for prosthetic components and transitional smile line. Removing cortical crestal bone can alter RFA and loading protocols.

Aim/Hypothesis

The purpose of this retrospective study is to compare the primary stability of implants placed with or without bone reduction and shelf preparation.

Material and Methods

Twenty patients were included in this study. The Primary predictor, bone reduction, was coded as a binary variable. Ten patients underwent bone reduction procedure, while the rest 10 patients do not receive bone reduction and shelf preparation prior to implant site preparation. Width, length, and density of the bone were also assessed as secondary predictor variables. Resonance Frequency Analyses (RFA) values and insertion torques (IT) of all implants were used as the outcome variable.

Results

Bone reduction and shelf preparation do not have a statistically significant effect on IT and RFA values of implants. While there was no statistically significant difference on IT and ISQ values regarding implants’ width and length, bone density has a statistically significant effect.

Conclusion and Clinical Implications

Bone reduction and shelf preparation do not affect the primary stability of implants as a single factor. Some other factors such as implant size and bone density should be considered to evaluate primary stability.