No abstract

Background and Aim: Oral lichen planus (OLP) is a chronic, inflammatory, T-cellmediated autoimmune oral mucosal disease. Oral lichenoid lesions develop as a type IV hypersensitivity reaction. Both of these entities are potential precancerous conditions; this adds to their clinical significance. The purpose of this literature review was to detect the similarities and the differences of these lesions to enhance the information of colleagues in managing these groups of patients. Materials and Methods: For this review, we searched Cochrane, Medline, and Embase databases from January 1990 to the end of October 2018. A total of 96 published papers, including review papers, case reports, cohort studies, case-control studies, and meta-analysis studies, were included and analyzed. Results: OLP and oral lichenoid reactions are two distinct diseases. They can be clinically similar but they have different etiologic factors. A histopathological study is necessary to differentiate them. Conclusion: The definitive diagnosis of these conditions is extremely important given their potentially premalignant nature. A timely diagnosis probably results in proper management. Based on the present research, the final differentiation between OLP and oral Lichenoid reactions relies on both clinical and histopathological manifestations according to the modified World Health Organization (WHO) criteria.

Objective: As there is no review study about cancer stem cells (CSCs) involved in the pathogenesis of oral lichen planus (OLP), for the first time we review the role of these cells in OLP and this hypothesis may be a clue for the evaluation of the premalignancy of OLP.Background: Cellular mediated immune responses are the main etiopathogenesis in OLP and it is a potentially premalignant lesion. One of the factors proposed in the pathogenesis of OLP and the comparable trend of this autoimmune disease to squamous cell carcinoma (SCC) are CSCs. CSCs have been detected in several solid tumors including head and neck cancers, and have special characteristics including metastasis and resistance to chemotherapy.Methods: Related keywords were searched and risk of bias assessment was done for each study.Conclusions: Among all of the studies reviewed in this article, all markers had increased expression in OLP compared to controls that are consistent with SCC. Only CD44 was in contradiction to other papers, in which different expression of CD44 strains was measured in different samples such as saliva and tissue.Based on the results of this review and more studies in the future by investigating the levels of these markers in OLP, it may be possible to determine the prognosis and course of the disease for each patient individually.

Background:Irrigation has a key role in the success of endodontic treatment. Intracanal irrigant solutions have adverse effects on the physical properties of dentin.Aim:The present study aimed to evaluate the effect of different irrigation protocols on coronal fracture resistance of endodontically treated teeth undergoing bleaching treatment.Design and Materials and Methods:Access cavities were prepared in 120 maxillary premolars which were divided into two groups (n = 60) – Group A: nonbleached, Group B: bleached (B). Each group was subdivided into five subgroups based on irrigation protocol (n = 12); G1: normal saline (NS), G2: 2.5% sodium hypochlorite (NaOCl), G3: 10% citric acid (CA), G4: 17% ethylene diamine tetra acetic acid, and G5: NaOCl plus CA. In Group B, the teeth were bleached using 38% hydrogen peroxide and 20% carbamide peroxide gels as in-office and at-home bleaching techniques for 3 weeks. All the teeth were restored with composite resin, thermocycled, and incubated for 24 h. The specimens underwent fracture resistance tests. Data were analyzed with ANOVA, Tukey honestly significant difference test, t-test, and Chi-squared test (α =0.05).Results:T-test showed significant differences between each two corresponding subgroups (P < 0.0001). In Group A, NS demonstrated significantly higher fracture resistance compared to others; however, minimum fracture resistance recorded in G2. In Group B, the maximum fracture resistance was recorded in G1, with the minimum being recorded in G5. Samples irrigated with NaOCl and NaOCl plus CA exhibited significantly lower fracture resistance compared to NS subgroup (P < 0.05).Conclusions:Within the limitations of this study, it can be concluded that the irrigation protocol used during endodontic treatment with/without bleaching can affect the coronal fracture resistance.