The Statistical Package for Social Sciences, version 19.0 (SPSS Inc., Chicago, IL, USA), was used for the statistical analysis. Data analysis involved descriptive statistics. Bivariate logistic regression analysis was conducted to measure the association between independent variables and the negative impact on OHRQoL. Multiple conditional logistic regression was used for the matched case–control study. All the three clinical conditions were included in the logistic model based on their clinical epidemiological importance. The significance level was set at 5%.