Effect of Hafnium Coating on Osseointegration of Titanium Implants: A Split Mouth Animal Study

Abstract

The behaviour of hafnium as surface coating in biological environments has not been studied. Little is known about osseointegration of hafnium-coated titanium implants. Thus, further studies of hafnium coating under biological conditions are required in order to determine the suitability of this material, as a surface coating for biomedical application. The aim of the study is to analyse the difference between hafnium-coated titanium and uncoated titanium by evaluating the osseointegration ability of hafnium metal and mechanism of which promotes better bone integration. The study was conducted with a split mouth design on 16 Wistar Albino rats of both sexes, at the age of 6-7 months, weighing 2526.5±74.4 g. Self-tapping titanium osteosynthesis screws (4 mm×2 mm) (LeForte System Bone Screw®) were implanted in the mandible of rats: Group A (pure titanium screws, n=12) and Group B (hafnium-coated screws, n=12). The implanted screws' stability was checked and noted with a specially customised torque apparatus during insertion and removal of implant. The tissue sections were then processed for hematoxylin and eosin and Masson's trichrome for bone and connective tissue examination, after 4 and 8 weeks of placement. Hafnium coating appears to have offered similar biocompatibility (aspartate transaminase (AST), alanine aminotransferase (ALT), and creatine kinase (CK) enzyme assay), statistically significant improvement (independent Student's t-test, p<0.05) in insertion torque (25.42±3.965) and removal torque (29.17±2.887) than commercially pure titanium with insertion torque (22.08±.575) and removal torque (25.42±2.575). Hafnium coating in the rat mandible showed promising osseointegration with good tissue biocompatibility. Further human trials of hafnium-coated implants are needed to understand the biological behaviour better to enhance clinical performance.