Oral psoriasis and temporo-mandibular disorders: A systematic review and meta-analysis

OBJECTIVES Psoriasis is a systemic, immune-mediated, inflammatory skin disease of unknown etiology. It affects 2-4% of the population in western countries and it is characterized by circumscribed, circular, red papules or plaques with a grey or silvery-white, dry scale. Although many studies reported possible association between pso­riasis and several oral conditions, the eventual association with temporo-mandibular disorders (TMD) still remains unsolved. The aim of this review was to analyze all the existing literature about the incidence of TMD in psoriatic patients and to determine their prevalence compared with healthy subjects. MATERIALS AND METHODS The authors designed a detailed protocol following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA Checklist). Following the PICO (Participants, Interventions, Comparators, Outcomes) format, a focused ques­tion was also developed: “It is pos­sible to find, both at the clinical exam and at the x-ray examina­tion, an increased incidence of TMD in adult subjects affected by psoriasis in comparison with healthy controls?”. A systematic review was performed, following a search strategy based on a combination of “Free text word” and MeSH (Medical Subject Headings) Terms. PubMed, Scopus, Web of Science and CENTRAL databases were used as search engines. Only observational, full-length, English language studies were investigat­ed. PROSPERO registration code is CRD42019127178. A me­ta-analysis was performed with the Review Manager software (Review Manager (RevMan) [Computer program]. Version 5.4, The Cochrane Collaboration, 2020). A “forest plot” graphic was used to show the results. The risk of bias was evaluated through a modified Newcastle Ottawa Scale. RESULTS Among 127 records screened, only 3 were included in this review. The meta-analysis was performed on the included case-control studies and mean prevalence and pooled odds ratio were calculated. The meta-analysis was performed on 300 cases and 401 controls and it revealed that patients suffering from psoriasis are nearly three times more likely to develop TMD: The mean prevalence of TMD in patients affected by psoriasis was 40.67% vs 16.96% in healthy subjects (OR = 2.94, 95% CI 1.1-7.9). CONCLUSIONS Although it has been reported how psoriasis can affect the joints, giving rise to a disease well known as psoriatic arthritis, TMJ involvement it has not been fully investigated. Only few studies provided scattered and not univocal results. The systematic review of the published literature showed an odds ratio of 2.94 of TMD onset in patients affected by psoriasis when compared to healthy subjects: This systematic review revealed a higher risk of TMD onset in psori­atic patients than general population. Future research should be conducted to rule out the mechanism underlying these associations and to investigate the behavior of oral manifestation in psoriatic patients in relation to their severity and treatment response. CLINICAL SIGNIFICANCE Within the limits of this study, the results of this systematic review highlight an increased risk of TMD onset in patients affected by psoriasis: A clinical strict follow-up could be recommended in order to prevent TMDs or to perform an early diagnosis.