An investigation of the influence of lubricants on implant insertion
I. Abstract: Primary stability is mandatory for osseointegration of dental implants. As reported by M. Norton, very high insertion torques can have negative impact on early osseointegration. Duyck reported increased marginal bone resorption around implants inserted with a torque of over 40Ncm. In an attempt to find a way for torque reduction, we focused on friction and conducted experiments using lubricants in view of the effects on friction reduction and the temperature rise on the surfaces. PubMed search by “insertion torque” and “implant + torque” resulted in 997 and 1801 hits, respectively. However, most of the torques reported are measurements in different environments. In this study, the effects of lubricants on torque reduction were evaluated using holes prepared in identical conditions.
II. Materials and Method: Implant holes were prepared on training blocks (Bone Fake Block, D3) and ASTRATECH Implant OsseoSpeed EV4.2 S 13mm (Dentsply Sirona) were inserted.
Experiment 1) Fixtures with no treatment (K) and lubricated by physiological saline (A), white petrolatum (B), moisture gel (C) and olive oil (D) were inserted with a torque of 20Ncm, and the insertion depth was measured.
Experiment 2) Using Newton-1 torque gauge (KTC, Kyoto, Japan), the torques required for full insertion without tapping (i) and with tapping (ii) were measured.
III. Results: In Experiment 1), the length left exposed was largest in K, followed by A, C, B and D. In Experiment 2), the torques required for full insertion without tapping was largest in K, followed by A, B, D and C. In groups with tapping, K required the largest torque, following by A, D, B and C.
IV. Discussion and conclusion: The factors affecting insertion torques include bone quality, implant hole condition, implant diameter, final drill diameter, implant design and cutting edge (friction coefficient). High insertion torques may cause high compressive stress to the surrounding bone. Insertion torques of over 40Ncm are reported to cause increased marginal bone resorption. In our experiments, different lubricants had different influence on insertion torques. Therefore, insertion torques should be discussed by clarifying the environment in which each measurement was made. The study demonstrated that the torques required for implant insertion into holes experimentally prepared in identical condition vary depending on the use and type of lubricant.