Implant Insertion Torque and Primary Stability

In the healing of long bone fractures, the absence of movement between the two parts of the fracture is essential for good healing: the movement, even at the micrometric level, can generate stress and tensions that prevent bone apposition in the gap. Even the primary stability of a dental implant is one of the main preconditions for osseointegration: in fact, during healing, micromovies that exceed the threshold of 100-150 microns can stimulate the growth of fibrous tissue in the bone to implant interface, leading to the failure of the procedure. It is also known that primary implant stability tends to decrease in the first weeks after placement due to inflammatory response due to surgical trauma before rising when bone recoating phenomena begin to prevail over reabsorption. Attention to implant stability is a crucial factor, especially in cases where immediate or early loading procedures are in place: system stress during chewing or simply related to tongue, cheeks or lips movements can result in micromovements that may lead to the failure of the procedure. With these assumptions, it is evident that a tool that allows the clinician to have a reliable evaluation of implant stability is the most important one: currently in use are the measurement of the insertion torque of the implant and the resonance frequency analysis. The insertion torque can be defined as the measurement of the resistance that the system encounters during its advancement in the apical direction by means of a rotating movement on its axis. Resonance frequency analysis is a not invasive method that evaluates rigidity of the bone system by measuring the size of the implant movement under a lateral force. High insertion torques have been proposed as a first rate technique to achieve a great implant stability, especially in cases to be treated with immediate or early load; Other studies point out that excessive insertion torques can cause both biological problems and mechanical to the implant. However, the relationship between insertion torque and implant stability is unclear: according to some in vitro studies, the two elements would be in direct relation, while others would be independent. The purpose of this prospective study is to evaluate in vivo the relationship between insertion torque value and implant stability measured using resonance frequency analysis in dental implants with a deep spire conical design.