Biological evaluation of precipitation hardened anodic oxidation orthodontic miniscrew in the beagle dog

Abstract

Biological evaluation of precipitation hardened anodic oxidation orthodontic miniscrew in theThis study presented was designed to analyze osseointegration potential and biological stability of orthodontic miniscrews with precipitation hardened anodic oxidized (PHAO) surface when compared with machined surface(MS) miniscrew. A total of 48 miniscrews were placed into the buccal alveolar bone of the mandible in 6 male beagle dogs. Comparison was made between precipitation hardened anodic oxidized surface miniscrew and machined surface miniscrews (Biomaterials Korea, Seoul, Korea). Maximum insertion torque (MIT) was measured using torque sensor (Mark-10, MGT 50, US) and initial mobility (Periotest, Simens, Germany) was recorded during installation. The force applied groups were reciprocally loaded by Ni-Ti coil spring (250~300 gm) at 3 and 12 weeks of loading period. Bone volume(BV) and bone implant contact(BIC) were also measured in histological section for each loading period. The obtained results were as follows:Machined surface(MS) miniscrews showed a higher MIT value of 21.68 Ncm compared with precipitation hardened anodic oxidized (PHAO) miniscrews by 21.53 Ncm, which showed no statistical difference (P>0.05). And the initial mobility depending on the types of miniscrew was not statistically different between surface types(P>0.05).At 3 weeks of loading the BIC of PHAO showed higher values of 65.4% than the values of MS miniscrews 52.9% respectively, and decreased by 61.7% and 44.5% respectively at 12 weeks of loading. And there was statistical difference between experimental groups at both loading period(P<0.05). At 3 weeks of loading, the BV was higher in PHAO(46.4 %) than MS miniscrews(36. 3%) showing statistical difference (P<0.05). At 12 weeks of loading, the BV of PHAO was 50.1% and MS miniscrews was 46.5%, but there was no statistical difference between two groups (P>0.05).These results showed that the BIC and BV of PHAO has a higher osseointegration potential than machined surface miniscrews at 3 and 12 weeks loading period. The PHAO’s initial stability might be superior to the MS miniscrews. However, the further investigation is required to compare with SLA and other surface modification miniscrews using the measuring the insertion and removal torque, mobility, success rate and so on.key words: anodic oxidation, miniscrew, insertion torque, bone implant contact, bone volume.