RESUMEN
AIM: To compare the impact of the two different root canal preparation systems on the quality of life of patients and correlate postoperative pain with the impact on quality of life. METHODOLOGY: A randomized clinical trial was conducted with 58 patients allocated into two groups based on the root canal preparation system employed: ProTaper Next (PN) or Reciproc (R). Data collection involved the administration of a questionnaire addressing demographic and clinical characteristics, the OHIP-14 (quality of life) and a visual analog scale (pain). The latter two were the outcomes of interest and were administered in the first 24 h after root canal treatment. The data were submitted to descriptive analysis, bivariate analysis, Poisson univariate and multiple regression, and Spearman's correlation test, with a 5% significance level. RESULTS: A greater frequency of impact after treatment was found for the items 'uncomfortable to eat food' and 'felt self-conscious'. No significant difference between groups was found regarding the severity of impact for total OHIP-14 score or any of the domain scores. CONCLUSIONS: The two root canal preparation systems exerted a similar impact on quality of life. Postoperative pain was correlated with impact on quality of life, affecting chewing function, self-consciousness and stress. Thus, it is important for dentists to provide care capable of preventing or treating the negative consequences of such therapy.