Effect of smoking status and nicotine dependence on pain intensity and outcome of treatment in Indian patients with temporomandibular disorders: A longitudinal cohort study

PURPOSE: Evidence regarding the association of smoking with various forms of chronic musculoskeletal pain is vast, but that with temporomandibular disorders (TMD) is scarce. AIMS: The aims of this study are to evaluate the effect of smoking status (SS) and nicotine dependence (ND) on TMD pain intensity and treatment outcome in an Indian population with TMD. SUBJECTS AND METHODS: Nine hundred and sixty-two patients with TMD were selected for this longitudinal cohort study. Lifetime SS was evaluated and patients were classified as current smokers (YS), former smokers (FS), or nonsmokers (NS). The Fagerstrom test was used to evaluate the ND of YS. Pain intensity was evaluated using visual analog scale scores. Six months posttreatment, the pain intensity was again recorded. The effect of treatment was evaluated using a global transition outcome measure and categorized as treatment success or failure. A minimum 30% reduction in pain was used as a criterion for categorizing patients as those who had gotten “better.” Data obtained from the study were compared using Chi-square tests, paired samples t-tests, and one-way ANOVA tests. The criterion for statistical significance for all analyses was set at P = 0.05. RESULTS: Among groups of SS, YS showed the maximum pain intensity at baseline and posttreatment. The outcome of treatment was most successful in NS and least in FS. The number of patients who had gotten “better” after treatment was significantly highest in NS. There was no significant difference between groups of ND with respect to pain intensity, treatment outcome, or “better” patients. CONCLUSIONS: Among Indian patients with TMD, smokers reported significantly greater pain intensity and poorer response to treatment than NS. Pain intensity or treatment outcome was independent of ND.