Microbiological analysis of autologous bone particles obtained by low-speed drilling and treated with different decontamination agents.

The aim of this study was to compare the effectiveness of three agents - two antibiotics (amoxicillin and clindamycin) and an antiseptic (chlorhexidine) - to decontaminate bone grafts obtained by low-speed drilling. The study included 248 bone tissue samples harvested from 62 patients by low-speed drilling before dental implant placement. Each of four samples obtained from every patient was dropped, using a sterile instrument, into a sterile tube containing a 500-µl solution of 400µg/mL amoxicillin, 150µg/mL clindamycin, 0.12% chlorhexidine, or physiological saline for 1min. The number of colony-forming units (CFU) was determined at 48h of culture. The use of clindamycin, amoxicillin, or chlorhexidine as decontaminant for 1min significantly reduced the CFU count when compared to physiological saline (control agent). In both anaerobic and CO2-rich atmospheres, significant differences in CFU/mL were found between the control and chlorhexidine groups (P<0.001), control and amoxicillin groups (P<0.001), control and clindamycin groups (P<0.001), chlorhexidine and amoxicillin groups (P<0.0001), and chlorhexidine and clindamycin groups (P<0.0001). In conclusion, clindamycin had the highest decontaminating effect on bone particles obtained by low-speed drilling, followed by chlorhexidine and amoxicillin. Clindamycin may therefore be a valid alternative option for the routine decontamination of intraoral bone grafts.

Topographic characterisation of dental implants for commercial use.

BACKGROUND: To characterize the surface topography of several dental implants for commercial use. MATERIAL AND METHODS: Dental implants analyzed were Certain (Biomet 3i), Tissue Level (Straumann), Interna (BTI), MG-InHex (MozoGrau), SPI (Alphabio) and Hikelt (Bioner). Surface topography was ascertained using a confocal microscope with white light. Roughness parameters obtained were: Ra, Rq, Rv, Rp, Rt, Rsk and Rku. The results were analysed using single-factor ANOVA and Student-Neuman-Keuls (p<0.05) tests. RESULTS: Certain and Hikelt obtained the highest Ra and Rq scores, followed by Tissue Level. Interna and SPI obtained lower scores, and MG-InHex obtained the lowest score. Rv scores followed the same trend. Certain obtained the highest Rp score, followed by SPI and Hikelt, then Interna and Tissue Level. MG-InHex obtained the lowest scores. Certain obtained the highest Rt score, followed by Interna and Hikelt, then SPI and Tissue Level. The lowest scores were for MG-InHex. Rsk was negative (punctured surface) in the MG-InHex, SPI and Tissue Level systems, and positive (pointed surface) in the other systems. Rku was higher than 3 (Leptokurtic) in Tissue Level, Interna, MG-InHex and SPI, and lower than 3 (Platykurtic) in Certain and Hikelt. CONCLUSIONS: The type of implant determines surface topography, and there are differences in the roughness parameters of the various makes of implants for clinical use.

Antigenic profile of osteoblasts present in human bone tissue sections.

The antigenic profile of human osteoblasts was previously analyzed by our group using primary cultures as study samples. These studies suggested a novel functional approach to this cell population. Osteoblasts have a characteristic antigenic profile and share antigens in common with other cell populations that also originate in the bone marrow. Some of the detected antigens are constitutively expressed, while others are modulated by different factors and/or cytokines. The aim of the present study was to analyze the antigens present in osteoblasts in vivo, since the presence of certain biomolecules in fetal bovine serum may modulate the antigenic expression, compromising the results. For this purpose, human bone tissue sections were analyzed with a wide panel of mAbs and using the immunoperoxidase technique. CD10, CD44 and alkaline phosphatase antigens and IL-12, IL-18 and IFNgamma cytokines were detected in osteoblasts in the bone tissue. However, CD80 and HLA-DR antigens were not found in all samples and when present their expression was weak. The expression of CD54 antigen was moderate or weak. These results allow data obtained by the primary culture of osteoblast-like cells to be endorsed.

Expression of molecules involved in antigen presentation and T cell activation (HLA-DR, CD80, CD86, CD44 and CD54) by cultured human osteoblasts.

BACKGROUND: Osteoblasts express the CD44 antigen and HLA class II antigens, molecules which, together with other costimulatory molecules such as CD80, CD86, and CD54, are involved in antigen presentation and T cell activation. The aim of this study was to investigate the expression of these molecules in human osteoblasts. METHODS: Human osteoblastic cells obtained from samples of normal bone obtained during mandibular osteotomy were isolated, maintained in culture, and characterized. The identity of the cells was confirmed by their alkaline phosphatase activity and their capacity to produce osteocalcin. Flow cytometry was used to examine the expression HLA-DR, CD80, CD86, CD44, and CD54 molecules involved in immune activities. RESULTS: We detected the expression of CD10, CD44, and HLA-DR antigens, molecules involved in antigen presentation in cultured osteoblastic cells. Although the cells were negative for CD45, the leukocyte common antigen and CD14 (an antigen detected on macrophages), they expressed CD54, CD80, and CD86 antigens, which are also involved in the mechanisms of antigen presentation to and activation of T cells. CONCLUSIONS: Our results suggest that osteoblastic cells or a subpopulation of these cells may have immune functions in bone. Further studies in which immune functions are assessed will be needed to test this hypothesis.

CD10 expression in cultured human osteoblast-like cells.

Morphological features, bone nodule formation and alkaline phosphatase activity are currently used to identify osteoblasts. CD10 (cALLa antigen) is a glycoprotein with endopeptidase activity and it is present on the surface of many cell types. We have studied the expression of CD10 in osteoblast-like cells by immunocytochemistry and flow cytometry in order to identify other markers of the osteoblast lineage. We isolated osteoblast-like cells from specimens obtained in the course of oral surgery. Expression of the cALLa antigen (CD10) may also be an indicator of the osteoblast phenotype.