Background The pathogenesis of medication overuse headache (MOH) involves hyperexcitability of cortical and trigeminal neurons. Derangement of the brainstem modulating system, especially raphe nuclei may contribute to this hyperexcitability. The present study aimed to investigate the involvement of the nucleus raphe magnus (NRM) in the development of cortical and trigeminal hyperexcitability in a rat model of MOH. Results Chronic treatment with acetaminophen increased the frequency of cortical spreading depression (CSD) and the number of c-Fos-immunoreactive (Fos-IR) neurons in the trigeminal nucleus caudalis (TNC). In the control group, muscimol microinjected into the NRM increased significantly the frequency of CSD-evoked direct current shift and Fos-IR neurons in the TNC. This facilitating effect was not found in rats with chronic acetaminophen exposure. In a model of migraine induced by intravenous systemic infusion of nitroglycerin (NTG), rats with chronic exposure to acetaminophen exhibited significantly more frequent neuronal firing in the TNC and greater Fos-IR than those without the acetaminophen treatment. Muscimol microinjection increased neuronal firing in the TNC in control rats, but not in acetaminophen-treated rats. The number of Fos-IR cells in TNC was not changed significantly. Conclusion Chronic exposure to acetaminophen alters the function of the NRM contributing to cortical hyperexcitability and facilitating trigeminal nociception.

Objectives To determine the oral health-related quality of life (OHRQoL) of temporomandibular disorder (TMD) patients at the final follow-up visit, and to investigate the associated factors. Materials and methods This cross-sectional study comprised 227 TMD patients. Dependent variable was OHRQoL determined by telephone interview using the 14-item Oral Health Impact Profile (OHIP-14) questionnaire after the final follow-up visit. Independent variables were collected from dental records, comprising age, sex, treatment duration, diagnosis, clinical parameters (mouth-opening distances), and pain perception. TMD patients were diagnosed as having masticatory muscle disorders (TMDM), temporomandibular joint (TMJ) disorders (TMDJ), or combined muscle and TMJ disorders (TMDC). Bivariate analyses and multivariable linear regression were used to analyze the factors associated with OHIP-14 scores. Results Bivariate analyses demonstrated higher OHIP-14 scores in younger patients, females, having TMDC, and lower mouth-opening distance. Multivariable analysis demonstrated the association of higher OHIP-14 scores with being younger and having TMDC. Participants with TMDC demonstrated greater improvement in unassisted mouth-opening distance, compared with the other clinical diagnosis groups. Conclusions At the final follow-up visit, oral health impact problems were reported mainly in physical pain and psychological discomfort domains. Better OHRQoL was found in older, and TMDM or TMDJ patients.

Objectives To determine the oral health-related quality of life (OHRQoL) of temporomandibular disorder (TMD) patients after occlusal splint treatment, and to investigate the associated factors. Materials and methods This cross-sectional study comprised 227 TMD patients. The dependent variable was OHRQoL determined by telephone interview using the 14-item Oral Health Impact Profile (OHIP-14) questionnaire. The independent variables were collected from dental record, comprising age, sex, treatment duration, clinical diagnosis, clinical parameters, and pain perception. The TMD patients were diagnosed as having masticatory muscle disorders (TMDM), temporomandibular joint (TMJ) disorders (TMDJ), or combined muscle and TMJ disorders (TMDC). Bivariate analyses were performed and multivariable linear regression was used to analyze the factors associated with the OHIP-14 score. Results The bivariate analyses demonstrated higher OHIP-14 scores in being younger, females, having TMDC, and lower mouth opening distance. The multivariable analysis demonstrated the association of higher OHIP-14 scores with being younger and having TMDC. The participants with TMDC demonstrated greater improvement in unassisted mouth opening distance, compared with the other clinical diagnosis groups. Conclusions After TMD treatment, oral health impact problems remained, but with low frequency. Better OHRQoL after TMD treatment was found in older and TMDC patients.