Preclinical study probing primary stability of dental implants in synthetic and natural bones

The natural bone is a biological example of a polymer–ceramic composite with a higher volume fraction of nanosized ceramic (around 65% hydroxyapatite) dispersed in polymer (collagenous) matrix. The loading of a dental implant involves the biomechanical interactions of the implant with such natural composites in the jaw bones of human subjects. In particular, the insertion torque responses of the dental implant are related to the implant design, in particular the external thread morphology, which influences the primary stability of the implant. In this study, the effect of the bone properties (polyurethane-based synthetic bone, porcine and human cadaver lumbar bone) and clinically relevant implant driving protocols on the insertion and removal torques of newly designed implant variants (hybrid threads with macro- and micro-threads) were assessed, quantitatively and qualitatively. It was observed that torque response increased with an increase in bone density, irrespective of the implant designs. The torque response of the implants in both synthetic and natural bones was benchmarked with the commercially available implant. The implants with bone cutting partial macro-threads at the apical end without inter thread gap exhibited comparable clinically relevant results with respect to control implants and were found to be most suitable for implantation into natural bone.