High Insertion Torque—Clinical Implications and Drawbacks: A Scoping Review

Abstract

Implant primary stability is a prerequisite for obtaining osseointegration and clinical success. Insertion torque (IT) is measured during implant placement and is expressed in Ncm. It represents the quantification of the frictional force experienced by the implant as it progresses apically through a rotational motion along its axis. Usually, to achieve osseointegration, a value within the range of 20-40 Ncm is desirable. Below a threshold of 20 Ncm, implants have a decrease in survival rate, while implant stability is guaranteed above 20 Ncm. The main goal of this study was to evaluate whether high values of IT affect osseointegration, implant health, and healing, by highlighting the positive and negative effects of IT > 50 Ncm on peri-implant bone, soft tissues, and long-term stability. This scoping review considered randomized clinical trials, observational studies, and cohort studies. Studies failing to meet the predefined inclusion criteria were excluded from the analysis. The review process adhered to the Preferred Reporting Items for Scoping Reviews (PRISMA-ScR) guidelines. Ultimately, a total of 11 studies were included in the final synthesis. Based on the studies included, the literature suggests that high values of IT guarantee adequate primary stability and better osseointegration. However, high IT is significantly associated with greater marginal bone loss, depending on bone density. Accordingly, IT values > 50 Ncm may provoke greater compressive forces with a negative impact on the jawbone. An elevated strain on the bone can induce necrosis and ischemia, due to an alteration of circulation, which in turn is responsible for marginal bone loss and reduced osseointegration. Lack of osseointegration ultimately leads to an early implant failure. As concerns soft tissue recession, a higher decrease is measured in implants placed with high-insertion torque. Nonetheless, additional clinical trials are warranted to assess long-term outcomes, quantify the incidence of these complications, and explore the impact of emerging clinical variables.