Effects of the application of low-temperature atmospheric plasma on titanium implants on wound healing in peri-implant connective tissue in rats.

PURPOSE: This study aimed to clarify the effects of surface modification of titanium (Ti) implants by low-temperature atmospheric pressure plasma treatment on wound healing and cell attachment for biological sealing in peri-implant soft tissue. METHODS: Hydrophilization to a Ti disk using a handheld low-temperature atmospheric pressure plasma device was evaluated by a contact angle test and compared with an untreated group. In in vivo experiments, plasma-treated pure Ti implants using a handheld plasma device (experimental group: PL) and untreated implants (control group: Cont) were placed into the rat upper molar socket, and samples were harvested at 3, 7 and 14 days after surgery. Histological evaluation was performed to assess biological sealing, collagen- and cell adhesion-related gene expression by reverse transcription quantitative polymerase chain reaction, collagen fiber detection by Picrosirius Red staining, and immunohistochemistry for integrins. RESULTS: In in vivo experiments, increased width of the peri-implant connective tissue (PICT) and suppression of epithelial down growth was observed in PL compared with Cont. In addition, high gene expression of types I and XII collagen at 7 days and acceleration of collagen maturation was recognized in PL. Strong immunoreaction of integrin α2, α5, and ß1 was observed at the implant contact area of PICT in PL. CONCLUSIONS: The handheld low-temperature atmospheric pressure plasma device provided hydrophilicity on the Ti surface and maintained the width of the contact area of PICT to the implant surface as a result of accelerated collagen maturation and fibroblast adhesion, compared to no plasma application.

Rat peri-implant soft tissue specifically expressed CXCL2 on titanium implant during wound healing.

Many of genes specifically expressed in peri-implant soft tissue (PIST) selected by microarray analysis are involved in the inflammatory response. This study investigated the gene expression and localization of PIST-specific inflammatory markers in PIST during wound healing. Pure titanium implants were implanted into the rat upper mandibular socket to create PIST. Samples were harvested from PIST as an experimental group, and tooth extracted area of oral mucosa tissue (OMT) and healthy periodontal tissue (PT) as control groups. The gene expressions of four standard inflammatory markers and nine PIST-specific inflammatory markers including chemokine (C-X-C motif) ligand 2 (CXCL2) during wound healing were examined. Immunoreactions of CXCL2 and immune cells in PIST and control tissues were compared. During wound healing, gene expression of PIST-specific inflammatory markers was higher in PIST than in OMT (p < .05), but there were no significant differences in the expression of standard inflammatory markers. The molecule CXCL2 was expressed locally at the implant-connective tissue interface, and localization of immune cells closely matched the CXCL2 expression pattern. In PIST, seven of PIST-specific inflammatory markers were expressed specifically and strongly during wound healing and their expression was maintained until the end of healing. Furthermore, CXCL2 expression was due to the creation of the implant-connective tissue interface, and it established a unique defense mechanism in PIST that was not apparent in OMT or PT.

The characteristic regulation of gene expression Lbp and Sod3 in peri-implant connective tissue of rats.

The aim of this study was to investigate the characteristic gene expression profile and localization of peri-implant connective tissue (PICT) compared with those of periodontal connective tissue (PCT) and oral mucosal connective tissue (OMCT). Upper first molar of 5-week-old rats were extracted and titanium implant were placed for PICT group. PCT and OMCT were used as control. Laser microdissected connective tissue at 4 weeks used for microarray analysis. The expression and localization of selected genes were confirmed by quantitative real-time PCR (qRT-PCR) and immunohistochemistry. Approximately, 1000 genes of upregulated and downregulated in PICT compared with PCT and OMCT were recognized. Based on the results of microarray analysis and qRT-PCR were demonstrated lipopolysaccharide binding protein (Lbp) as a specific upregulated gene and superoxide dismutase 3 (Sod3) as a specific downregulated gene in PICT. Immunoreaction of LBP and F4/80 as macrophage marker localized to subepithelial and implant facing connective tissue in PICT. SOD3 expression was not observed in PICT, reactive oxygen species, a target of superoxide dismutase, was strongly and locally expressed in all three tissues. Our data suggested that the upregulation of Lbp and downregulation of Sod3 are as characteristic gene expression pattern in PICT.