Bacteria associated with apical periodontitis promotes in vitro the differentiation of macrophages to osteoclasts.

OBJECTIVE: To analyze the possible in vitro effect of the cytokine RANKL and bacteria involved in apical periodontitis on the differentiation of macrophages into osteoclasts. MATERIAL AND METHODS: Bacteria were isolated (mainly E. faecium and E. faecalis) from the root canal of fifty patients with apical periodontitis, the possible effect of these bacteria on the phagocytic activity of the monocyte cell line THP-1 was analyzed by flow cytometry. Furthermore, the effect of these bacteria (alone or in combination with the cytokine RANKL) on the differentiation of THP-1 macrophages into osteoclasts was analyzed through the expression of the receptor RANK and the tartrate-resistant acid phosphatase TRAP. Finally, the release of different cytokines (IL-1ß, TNF-α, IL-6, IL-8, IL-10, and IL-12p70) by THP-1 cells induced to differentiate into osteoclasts was also analyzed. RESULTS: We observed a significant proportion of THP-1 cells were able to internalize E. faecium and E. faecalis. Furthermore, these bacteria were able to induce (alone or in combination with RANKL) a significant expression of RANK by THP-1 macrophages; accordingly, E. faecium and E. faecalis induced very significant levels of TRAP in these cells. Finally, during the differentiation of THP-1 macrophages induced by RANKL or bacteria, a significant release of the pro-inflammatory cytokines IL-6 and TNF-α was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Our data suggest that the causative agents of apical periodontitis can induce the differentiation of osteoclasts as well as the release of pro-inflammatory cytokines, phenomena that may have an important role in the bone damage observed in this condition.

Effectiveness of oxidative potential water as an irrigant in pulpectomized primary teeth.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of oxidative potential water (OPW) as an irrigating solution in reducing bacterial loading in necrotic pulpectomized primary teeth. STUDY DESIGN: Forty necrotic teeth were included, 20 irrigated with OPW (experimental group) and 20 with 1% NaOCl (control group); in both groups, 2 microbiological samples from within the canals were taken with a sterile paper point, the first before irrigation (immediately before opening the crown), and the second after instrumentation and final irrigation (before filling). All samples were evaluated by McFarland's scale. RESULTS: After the samples were analyzed before and after irrigation in the control group, there was a significant decrease in bacterial load, as in the experimental group (P < 0.0001). When both groups were compared post irrigation, no significant difference was observed (P = 0.1519). CONCLUSION: The OPW was as effective as the NaOCl and is suggested as an alternative for irrigating after pulpectomy of necrotic primary teeth.