Methyl mercaptan and hydrogen sulfide products stimulate proinflammatory cytokines in patients with necrotic pulp tissue and endodontically treated teeth.

Bacterial infections of the residual dentin or infected pulp tissue are responsible for most cases of endodontic treatment failures. Persisting microorganisms in necrotic pulp tissue produce sulphur components such as methyl mercaptan and hydrogen sulfide as well as thioether derivatives. Although there is emerging evidence that these sulphur compounds stimulate immune cells and induce the inflammatory cascade, the immunological mechanisms of local and systemic inflammation have not been described. In this retrospective study we evaluated the ex-vivo immune response of peripheral blood mononuclear cells to sulphur compounds in 53 patients with clinical or radiologic endodontic treatment failure, 20 patients with clinical discomfort or radiological findings without previous endodontic treatment and a control group of 31 patients who had received successful endodontic treatment at least five years previously. Patients with endodontic abnormalities showed significantly higher ex-vivo sulphur compound-stimulated interferon-gamma (IFN-γ) and interleukin-10 (IL-10) levels as compared to the control group. The association between ex-vivo-stimulated cytokines and endodontically derived sulphur compounds was further substantiated by the fact that the number of IFN-γ and/or IL-10-positive patients decreased significantly 3-8 months after re-treatment of the root canal or tooth extraction. Furthermore, serum tumor necrosis factor-alpha (TNF-α) levels were higher in patients than in controls, and at the same time, the TNFA -308 G/A polymorphism was associated with endodontic treatment failure in our study population. We conclude that a cellular immune response to sulphur compounds contributes to the inflammatory process observed in relation to endodontic treatment failures.

The influence of atopy in the prognosis of the replantation of avulsed teeth.

BACKGROUND: Replantation is the most indicated procedure for traumatic dental avulsion, but it invariably results in a greater or lower degree of root resorption. The outcomes of these cases can be affected by some well-known factors. Because studies have shown the importance of the innate and acquired immune response in the mechanisms involved in the resorption of bone tissues, an endeavor was made to verify if such an influence applies to dental resorption. METHODS: Fifty-seven avulsed, endodontically treated teeth were assessed in the Endodontics Clinic, Pontifical Catholic University of Paraná. Follow-up of the replanted teeth included periodical clinical examinations and radiographs, in accordance with the control rules of the International Association of Dental Traumatology. The evaluation of atopy was based on the patient's personal and family history in conjunction with the skin-prick test for five allergen extracts. RESULTS: Of the 46 teeth with a favorable outcome, 33 (71.74%) were in atopic patients, and 13 (28.26%) were in non-atopic patients. Of the 11 teeth with an unfavorable outcome, four (36.36%) were in atopic patients, and seven (63.64%) were in non-atopic patients; a greater prevalence of unfavorable prognoses occurred in non-atopic patients. CONCLUSION: The outcome after 1 year for avulsed and replanted teeth is more favorable in atopic patients.