Aerosol deposition of hydroxyapatite and 4-hexylresorcinol coatings on titanium alloys for dental implants.

Aerosol deposition is a newly developed technique, and it can deliver the drug from a hydroxyapatite (HA)-coated surface. 4-Hexylresorcinol (4-HR) is a well-known antiseptic. The influence of the 4-HR component of HA coatings on titanium surfaces was studied in vitro and in vivo. X-ray diffraction and Fourier transform infrared techniques were used for the evaluation of the coating. The cellular response of the coating was evaluated by scanning electron microscopic study, MTT assay, alkaline phosphatase assay, and osteocalcin assay. In addition, the dental implant was coated with HA or HA + 4-HR. The implant was installed into the tibia of a rabbit after contamination by Aggregatibacter actinomycetemcomitans. The torque test and histologic analysis were then performed at 8 weeks after the operation. By use of an aerosol deposition technique, the combination of HA and 4-HR was successfully coated onto a titanium surface, which was confirmed by x-ray diffraction and Fourier transform infrared techniques. MG63 cells attached more rapidly to the HA + 4-HR coating than to the HA-only coating. The HA + 4-HR coating had significantly increased osteocalcin expression and alkaline phosphatase activity compared with the HA-only coating (P < .05). The dental implant coated with HA + 4-HR had a significantly higher removal torque value than that coated with HA alone at 8 weeks after surgery (P < .05). On histologic analysis, both the bone formation value and the bone-to-implant contact value were significantly higher in the HA + 4-HR group than in the HA-only group at 8 weeks after surgery (P < .05). Collectively, the HA + 4-HR-coated dental implant had clear advantages over the HA-coated dental implant. Therefore HA + 4-HR coatings can be considered for patients who need immediate implant installation after tooth extraction or who have poor-quality bone.