Onset of oral lichen planus following dental treatments: A nested case-control study

Introduction The exposure to amalgam restorations has been reported to bring about altered immunity followed by inflammation and infection. Aims This study aimed at identifying whether patients who received restorative or endodontic treatments, or tooth extraction, would have altered odds of developing oral lichen planus (OLP). Material and methods In this population-based nested case-control study, 421 cases of OLP and 1,684 controls were included after propensity score matching. Logistic regression was used to estimate the adjusted odds ratio (aOR) of OLP in individuals who had received amalgam and composite resin restorations, root canal therapy, and tooth extraction over a follow-up duration of five years. Results There were no significantly different odds of OLP for those who underwent either amalgam (aOR = 0.948, 95% CI = 0.853-1.053, p = 0.3170) or resin restorations (aOR = 1.007, 95% CI = 0.978-1.037, p = 0.6557) in both anterior and posterior teeth in an observational period of five years after restorations. Root canal therapy was associated with significantly lower odds of OLP, with each additional root canal therapy attenuating the risk of OLP at an aOR of 0.771 (95% CI = 0.680-0.874, p = 0.0001) for both anterior (aOR = 0.786, 95% CI = 0.626-0.986, p = 0.0372) and posterior teeth (aOR = 0.762, 95% CI = 0.650-0.893, p = 0.0008). Likewise, each tooth extraction reduced the risk of OLP, with an aOR of 0.846 (95% CI = 0.772-0.927, p = 0.0003), especially for anterior teeth (aOR = 0.733, 95% CI = 0.595-0.904, p = 0.0037). Conclusions We reported no significant association between dental restorations and consequent OLP, and significantly lower odds of OLP following both root canal therapy and tooth extraction.