Influence of different drilling protocols and bone density on the insertion torque of dental implants

The insertion torque of dental implants will depend on a combination of different factors such as bone density, the design of the implant and the drilling protocol used. However, it is not clear how the interaction of these factors affects the final insertion torque and which drilling protocol should be used in each clinical situation. The aim of this work is to analyse the influence of bone density, implant diameter and implant length on the insertion torque using different drilling protocols.

An experimental study was carried out in which the maximum insertion torque was measured, in standardised polyurethane blocks (Sawbones Europe AB) of four densities, for M12 Oxtein dental implants (Oxtein, Spain) with diameters of 3.5, 4.0, 4.5 and 5mm, and lengths of 8.5mm, 11.5mm and 14.5mm. All these measurements were carried out following four drilling protocols, a standard protocol, adding a bone tap, cortical drill or conical drill. In this way, a total of 576 samples were obtained. For the statistical analysis, the table of confidence intervals, mean, standard deviation and covariance was carried out, in total and grouped by the parameters used.

The insertion torque for D1 bone obtained very high levels, reaching 77 6.95 N/cm, these values improved with the use of conical drills. In D2 bone, the mean torque obtained was 37.89± 13.70N/cm, with values within the standard. In D3 and D4 bone significantly low torques were obtained with values of 14.97± 4.40N/cm and 9.88± 4.16N/cm (p>0.001) respectively.

In D1 bone, conical drills must be incorporated in drilling to avoid excessive torque, while in D3 and D4 bone, these would be contraindicated, as they drastically decrease the insertion torque, which may compromise the treatment.