Oral potentially malignant disorders (OPMD) are chronic conditions, which have a higher risk of transformation to oral squamous cell carcinoma. The aim of this systematic review and meta-analysis was to answer the question: "What is the prevalence of oral potentially malignant disorders among adults?" Studies reporting the prevalence of these conditions (leukoplakia, erythroplakia, oral submucous fibrosis [OSMF], and actinic cheilitis) were selected, only studies in which a clinical assessment and histopathological confirmation were performed were included. Of the 5513 studies, 22 met the inclusion criteria for qualitative and quantitative analyses. The risk of bias (RoB) of the selected studies was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data. Seven studies were classified as high risk, 12 as moderate risk, and 3 as low RoB. The meta-analysis showed that the prevalence of OPMD was 4.47% (95% CI = 2.43-7.08). The most prevalent OPMDs were OSMF (4.96%; 95% CI = 2.28-8.62) and leukoplakia (4.11%; 95% CI = 1.98-6.97). OPMDs were identified more commonly in males (59.99%; 95% CI = 41.27-77.30). Asian and South American/Caribbean populations had the highest prevalence rates of 10.54% (95% CI = 4.60-18.55) and 3.93% (95% CI = 2.43-5.77), respectively. The overall prevalence of OPMD worldwide was 4.47%, and males were more frequently affected by these disorders. The prevalence of OPMD differs between populations; therefore, further population-based studies may contribute to the better understanding of these differences.

Background: The aim of this systematic review (SR) was to summarize and critically appraise available evidence on the association of the immunohistochemical expression of matrix metalloproteinases (MMPs) with the occurrence of lymph node/distant metastasis of oral squamous cell carcinoma (OSCC).Methods: Searches were conducted in five main electronic and three gray literature databases.Results: From 2128 records identified, 50 were included for qualitative analysis. A total of 12 MMPs were identified (--26, and MT1-MMP). Most included studies reported a positive association of MMP-1, -2, -3, -7, -9, and MT1-MMP with lymph node metastasis. MMP-8, -25, and -26 were not associated with lymph node metastasis.Conclusions: According to this SR, MMP-1, -2, -3, -7, -9, and MT1-MMP seem to play an important role in lymph node metastasis of OSCC. K E Y W O R D Simmunohistochemistry, lymphatic metastasis, matrix metalloproteinases, mouth neoplasms, neoplasm metastasis, systematic review

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The aim of this study was to investigate the immunoexpression of matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinase 1 (TIMP-1), and vimentin (VIM) and its association with the inflammatory reaction (IR) and clinical parameters in oral epithelial dysplasia (ED). The sample was composed of 66 cases of ED, 27 oral squamous cell carcinoma (OSCC), and 28 nonneoplastic epithelium (NNE). ED was graded according to the binary system as low-risk ED (n = 42) and high-risk epithelial dysplasia (HRED: n = 24). The IR was defined as the median number of inflammatory cells present on the connective tissue in 5 consecutive fields. Tissue sections of paraffin-embedded samples were immunohistochemically stained; MMP-9 and TIMP-1 expression was analyzed separately in the epithelium and the connective tissue; VIM was analyzed in the epithelium. Clinical parameters such as age, sex, lesion site and clinical presentation, alcohol/tobacco use, and malignant transformation of ED were retrospectively obtained from medical records. Nonhomogeneous leukoplakia presented higher odds (3.857; 95% confidence interval: 1.16-12.85) of being graded as HRED than did homogeneous lesions. The IR was higher in OSCC and ED than in NNE, and correlated with the epithelial expression of VIM. HRED and nonhomogeneous leukoplakias presented higher IR than did low-risk ED and homogeneous leukoplakias. Alcohol users had higher IR than nonalcohol users. Smokers had higher epithelial expression of MMP-9 and VIM. High IR in OSCC and HRED, and its positive correlation with VIM expression suggest a contribution of the IR in the progression of OSCC. Moreover, the high expression of MMP-9 and VIM in smokers implies its involvement in tobacco carcinogenesis.

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