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This study was designed to evaluate the efficacy of low-level laser therapy (LLLT) in the treatment of temporomandibular disorders (TMDs). We searched electronic databases and references lists of relevant articles, retrieved all of the published randomised controlled trials in regard to these issues and then performed a meta-analysis. Fourteen highly qualified RCTs reporting on a total of 454 patients, which evaluated the effectiveness of LLLT for patients suffering from TMDs were retrieved. The results indicated that LLLT was not better than placebo in reducing chronic TMD pain (weighted mean difference = -19·39; 95% confidence interval = -40·80-2·03; P < 0·00001; I(2)  = 99%). However, the LLLT provided significant better functional outcomes in terms of maximum active vertical opening (MAVO) (weighted mean difference = 4·18; 95% confidence interval = 0·73-7·63; P = 0·006; I(2)  = 73%), maximum passive vertical opening (MPVO) (weighted mean difference = 6·73; 95% confidence interval = 01·34-12·13; P = 0·06; I(2)  = 73%), protrusion excursion (PE) (weighted mean difference = 1·81; 95% confidence interval = 0·79-2·83; P = 0·59; I(2)  = 0%) and right lateral excursion (RLE) (weighted mean difference = 2·86; 95% confidence interval = 1·27-4·45; P = 0·01; I(2)  = 73%). The results of our meta-analysis have provided the best evidence on the efficacy of LLLT in the treatment of TMDs. This study indicates that using LLLT has limited efficacy in reducing pain in patients with TMDs. However, LLLT can significantly improve the functional outcomes of patients with TMDs.

Objective To investigate the efficacy of low-level laser therapy (LLLT) treatment of knee osteoarthritis (KOA) by a systematic literature search with meta-analyses on selected studies. Design MEDLINE, EMBASE, ISI Web of Science and Cochrane Library were systematically searched from January 2000 to November 2014. Included studies were randomized controlled trials (RCTs) written in English that compared LLLT (at least eight treatment sessions) with sham laser in KOA patients. The efficacy effective size was estimated by the standardized mean difference (SMD). Standard fixed or random-effects meta-analysis was used, and inconsistency was evaluated by the I-squared index (I2). Results Of 612 studies, nine RCTs (seven double-blind, two single-blind, totaling 518 patients) met the criteria for inclusion. Based on seven studies, the SMD in visual analog scale (VAS) pain score right after therapy (RAT) (within 2 weeks after the therapy) was not significantly different between LLLT and control (SMD = −0.28 [95% CI = −0.66, 0.10], I2 = 66%). No significant difference was identified in studies conforming to the World Association of Laser Therapy (WALT) recommendations (four studies) or on the basis of OA severity. There was no significant difference in the delayed response (12 weeks after end of therapy) between LLLT and control in VAS pain (five studies). Similarly, there was no evidence of LLLT effectiveness based on Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain, stiffness or function outcomes (five and three studies had outcome data right after and 12 weeks after therapy respectively). Conclusion Our findings indicate that the best available current evidence does not support the effectiveness of LLLT as a therapy for patients with KOA.

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The most fundamental function of an epithelial tissue is to act as a barrier, regulating interactions between the external environment and the body. This barrier function typically requires a contiguous cell layer but since teeth penetrate the oral epithelium, a modified barrier has evolved, called the junctional epithelium (JE). In health, the JE attaches to the tooth, sealing the inside of the body against oral micro-organisms. Breakdown of the JE barrier results in periodontal ligament (PDL) disintegration, alveolar bone resorption, and ultimately tooth loss. Using lineage tracing and DNA pulse-chase analyses, we identified an anatomical location in the JE that supported both fast- and slow-cycling Wnt-responsive stem cells that contributed to self-renewal of the tissue. Stem cells produced daughter cells with an extraordinarily high rate of turnover that maintained JE integrity for 1.4 y in mice. Blocking cell proliferation via a chemotherapeutic agent 5-fluorouracil (5-Fu) eliminated fast-cycling stem cells, which caused JE degeneration, PDL destruction, and bone resorption. Upon removal of 5-Fu, slow-cycling stem cells regenerated both the structure and barrier function of the JE. Taken together, our studies identified a stem cell population in the JE and have potential clinical implications for prevention and treatment of periodontitis.