Wedge Shaped vs Round Implants: Bone Strain During the Insertion Process.

A novel implant system resembling the shape of a wedge and employing piezosurgery for implant bed preparation has been introduced with the aim of solving the problem of horizontal bone deficiency. This in vitro study compared emerging bone strain during insertion of a conventionally round implant vs the wedge implant. Adhering to the manufacturers' protocols, implant surgery was performed in polyurethane foam blocks equipped with strain gauges attached to the buccal and occlusal surfaces. Five implants per group were placed while strain development during insertion was recorded. Primary implant stability was determined using resonance frequency analysis. Statistical analysis was based on Welch's 2-sample tests (α = 0.05). In general, greater strain development was found on the buccal aspect of bone compared to the occlusal aspect with an overall range between -724 μm/m and 9132 μm/m. A stepwise increase in strain development was seen in the wedge implants while, in the round implants, a continuous increase in strain development was recorded. Absolute strain development on the buccal aspect of bone was significantly greater in wedge implants (P = .0137) while, on the occlusal aspect, significantly lower strain development was seen for wedge implants (P = .0012). Primary stability of wedge implants was significantly lower compared to round implants (P = .0005). Wedge implants differ from round implants with respect to the insertion process characterized by a stepwise increase in bone deformation. High strain development in buccal bone may constitute a risk factor for bone resorption and should be avoided by reducing the degree of underpreparation of the implant site.