Date of Completion
Background: To better understand the effect of implant surface modification on bone, more information is needed on the early stages of bone healing around dental implants in vivo. Quantitative reverse transcription polymerase chain reaction (QRT-PCR) is a method that can be utilized to evaluate the early stages of peri-implant wound healing at molecular level by analyzing the level of gene transcription. In addition, the level of protein expression can be analyzed by immunohistoflourescence (IHF). A pilot study was performed to evaluate the expression of the osteogenic genes/biomarkers, and the quantity/quality of bone in contact with the implant during the early healing around titanium SLA, titanium SLActive, and titanium zirconium SLActive (Roxolid) implant surfaces in the miniature pigs. Main objective of this pilot study was to optimize the research methodology of studying the early bone healing at the molecular level with QRT-PCR and IHF in the miniature pigs. Methods: Total of 36 bone chamber implants were implanted in the mandible of 6 mini pigs. Each hemi mandible received three randomly allocated bone chamber implants on both sides in a split-mouth design. Animals were sacrifice at 3 days and 2 weeks of healing period. One hemi mandible was foreseen for histological and histomorphometrical analysis. The other hemi mandible was foreseen for IHF analysis. The presence of B-catenin, Runx2, Osteopontin(Opn), and Osteocalcin(Ocn) were measured by IHF. RNA was isolated from two animals at 2 weeks; Osterix(Osx), Opn and Ocn mRNA expression levels were evaluated for osteoblasts differentiation by QRT-PCR. Results: No significant histological difference was recorded between the different implant types at each sacrifice time point. Histomorphometrical analysis showed that there was no significant difference between the groups concerning the bone area in total area in bone chambers at 3 days and 2 weeks. QRT-PCR at 2 weeks showed that SLActive have the highest Opn and Ocn mRNA expression and the lowest Osx expression. Two fold higher expression of Osx was reported on SLA and Roxolid compared to SLActive. At 3 days, none of the biomarkers were detected by IHF in this miniature pig model. At 2 weeks, Ocn was only detectable biomarker which was expressed highest by SLActive followed by Roxolid and SLA; however, there was no statistically significant difference between the groups in the level of Ocn expression. Conclusions: Within the limitations of this initial study, it might be concluded that the combination of QRT-PCR and IHF is a valuable technique to evaluate the early stages of wound healing around endosseous implants. These preliminary data suggest earlier expression of Ocn with SLActive compared to SLA and Roxolid. Thus SLActive may entail enhanced osteoconductive properties when compared to the other surfaces tested in this experiment. However, further experimental studies of higher power are needed in order to validate the research methods and to confirm these preliminary findings.
Kim, Yung Kyun DDS, "Osteogenesis During Early Healing Around Titanium and Titanium Zirconium Implants: Immunohistochemistry and mRNA Expression of Bone Markers in Miniature Pigs" (2011). Master's Theses. Paper 176.