The Effect of Implant Surface Coated with Lovastatin n Osseointegration
Date Issued
2009
Date
2009
Author(s)
Chen, Ping-Han
Abstract
Objectiveshe 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, i.e., statins, are widely used for the treatment of hyperlipidemia. Recently, experimental studies demonstrated that statins induced the promoter of bone morphogenetic protein-2 (BMP-2) mRNA in osteoblasts and stimulated bone formation. Further, the positive effects of statins on bone formation in animal studies have been reported. ovastatin, a member of the drug class of statins, has the ability to induce bone formation in animal models. The purpose of this study was to compare, histomorphometrically and biomechanically, the bone response to lovastatin coated titanium implants with controls after implantation in the tibia of dogs. aterials and methodsen-mm-long Ti-6Al-4V screw-type implants, with 4mm in diameter were used in the present study. Two different implant surfaces, machined and rough surface were designed for test. The lovastatin was diluted into a low dosage(20μM) and a high dosage(200μM) for implant coating. A total of 108 implants were inserted in the tibia of 9 dogs and assigned into two healing time periods, 2 weeks and 4weeks. The implants were divided into six groups as follows (nine implants in each group): machined surface (M), rough surface (R), machined surface with low-dose lovastatin (ML) and with high-dose lovastatin (MH) , and rough surface with low-dose lovastatin (RL) and with high-dose lovastatin (RH). ach tibia provided six sites assigned to the six implant groups. Location of different implants was assigned according to a randomized schedules established. The implant site was prepared a hole of 3.85mm in diameter and 10mm in depth. The crestal 2.0 mm of implant sites were widened to 4.2mm. There was no primary stability when the implants were inserted into the prepared sites. he animals were sacrificed at 2 weeks or 4 weeks after implant placement. The tibias were dissected and prepared into the block sections of implants. Then, the percentage of bone-to-implant contact (BIC) was observed under scanning electronic microscope, and the removal torque was measured with torque gauge manometer.esults he histomorphometric analysis showed that, after 2 weeks of healing, among the machined surface groups, the percentage of BIC was statistically greater for the lovastatin coated implants than for the controls(P<0.05) and this finding was less evident after 4 weeks. No significant difference was observed among rough surface groups after 2 or 4 weeks of healing. n the removal torque test, the lovastatin-coated machined groups (14.17 and 13.00 Ncm) had statistically higher torque force than non-coated machined group (9.63Ncm) after 2 weeks of healing. But this difference was not found in rough surface groups. At 4 weeks, there were no remarkable difference in removal torque between lovastatin coated implants and control implants, neither among rough surface nor machined surface groups. n removal torque test, there were higher values of removal torque in rough surface groups than those of machined surface groups at 2 or 4 weeks after implantation. In histomorphometric analysis, the rough surface implants had statistically greater BIC than machined surface implants after 2 weeks, but this difference was no longer evident after 4 weeks.onclusionhe data from the present study demonstrated that lovastatin may accelerate new bone deposition and improve bony anchorage around machined surface dental implants after 2 weeks and 4 weeks of healing. The increased BIC and removal torque force suggest the possibility of a further reduction of the healing period following implantation. However, the influences of the dosage of lovastatin and its mode of delivery on osseointegration need more in vitro and in vivo studies to clarify this issue.
Subjects
surface topography
removal torque
bone-to-implant contact
osseointegration
lovastatin
Ti-6Al-4V titanium implant
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