A reliable option for replacing teeth is the insertion of osseointegrated implants. Dental implant primary stability (DIS) has also been reported to be a fundamental prerequisite for long-term success of dental implants, even though osseointegration has also been achieved without a certain amount of primary stability. Primary stability has been defined as the ability to withstand axial, lateral, and rotational loading and depends on the implants’ anchorage within the bone. The creation of different implant geometries and drilling protocols seems to have improved the achievement of high primary stability within the bone. The interaction between the implants’ geometric properties, combined with the surgical drilling technique indicated for the detected bone density can contribute to obtaining low amounts of compressive stress and micromotions on the surrounding bone tissue during placement.

For evaluation of in vivo primary stability, insertion torque (IT) and resonance frequency analysis (RFA) are well-established methods. IT is a mechanical parameter influenced by surgical procedure, implant design, and bone quality. It has been defined by the Foundation for Oral Rehabilitation as the cutting resistance of the bone during implant insertion, the friction, and has been considered an indirect value of implant primary stability. Values above 32 Ncm indicate that the implant is firmly embedded in the bone and mechanically stable.

RFA assumes that the frequency is directly related to the stiffness of the bone-implant interface and the surrounding bone. High values show a stable implant and allow verification of osseointegration and secondary stability over time. RFA is measured by Ostell®-devices (Osstell ISQ, Osstell, Göteborg, Sweden). A sensor (SmartPeg, Osstell, Göteborg, Sweden) is mounted on the implant and is vibrated by moving it with magnetic pulses.