Effect of thread characteristics on primary stability of dental implants

One of the key factors in the success of dental implantation is osseointegration - fusion of the implant with the bone. Excessive micromobility on the implant-bone surface under loading disrupts osseointegration. A natural question arises: is it possible to minimize micromobility by controlling the structural characteristics of the implant, in particular, the threads? The influence of the thread characteristics (profile, depth and thread pitch) on the stability of dental implants under immediate loading (primary stability) is studied in the paper, when osseointegration has not yet occurred and there is no complete adhesion at the implant-bone interface. The change in the thread profile is modeled by a variation in the angle of inclination of the sides of the profile with a gradual transition from the triangular through the trapezoidal and square threads to the dovetail one. The minima of the maximum displacements on the implant-bone interface are obtained for the square and dovetail profiles. Their values are microns, which corresponds to the data of other papers. The influence of the depth and pitch of the thread is studied on a square profile. It has been established that an increase in the thread depth from 0.1 to 0.4 mm (as well as a reduction in the thread pitch from 2 to 0.4 mm) led to a 3-6% decrease in the implant subsidence (global mobility) and to a significant (multiple) monotonic drop in movement at the interface. Thus, the profile of the thread has a significant effect on the micromobility on the implant-bone surface under loading: with the same values of the occlusal load and observed tooth macromomobility, it can change micromobility by times. The micromotion minima are obtained for the square and dovetail profiles. The maxima of local displacements arise on the apex turn of the thread.