Insertion torque curve

In 2000, O’Sullivan reported torque curves for a prosthetic implant for the first time, and evaluated the characteristics of the tapered type by torque curves obtained by inserting five kinds of implants into the maxillary bone of unembalmed human cadavers. In a subsequent review, Meredith cited six kinds of torque curves when the final osteotomy diameter was changed and described that a torque curve rose more markedly with a thinner implant cavity.

In 2011, Kim et al. compared a case with a self-tapping blade and a case without a self-tapping blade using their torque curves with artificial bone. In 2012, Park et al. obtained the maximum insertion torque, angular momentum, and total insertion energy by torque curves, although quantitative analyses on whether torque curves were correlated with implant designs were not conducted. Furthermore, most conventional studies on torque have focused on measurement of the maximum torque value and/or RT at the time of IT or the relationship between the RFA value and IT and/or RT.

The present study was not limited to measurements of IT and RT, as the characteristics of the torque curves were divided into four areas designated as the initial, parallel, tapered, and platform areas, and quantitative analyses were performed for each area. For the initial area, a rapid rise in torque occurring immediately after insertion for 1–2 s was observed, and torque value rises of 1.43–2.26 N · cm were also recognized. This reflects torque generated by the implant placed at the predetermined position on the prepared hole rotating and rubbing with the artificial bone with the load of 500 g, and it is presumed that the rapid rise in the initial area was a phenomenon when the thread ridge was inserted into the artificial bone.