Anti-plaque effect of a synergistic combination of green tea and Salvadora persica L. against primary colonizers of dental plaque

Objective Green tea (Gt), leafs of Camellia sinensis var. assamica, is widely consumed as healthy beverage since thousands of years in Asian countries. Chewing sticks (miswak) of Salvadora persica L. (Sp) are traditionally used as natural brush to ensure oral health in developing countries. Both Gt and Sp extracts were reported to have anti-bacterial activity against many dental plaque bacteria. However, their combination has never been tested to have anti-bacterial and anti-adherence effect against primary dental plaque colonizers, playing an initial role in the dental plaque development, which was investigated in this study. Methods Two-fold serial micro-dilution method was used to measure minimal inhibitory concentration (MIC) of aqueous extracts of Gt, Sp and their combinations. Adsorption to hexadecane was used to determine the cell surface hydrophobicity (CSH) of bacterial cells. Glass beads were used to mimic the hard tissue surfaces, and were coated with saliva to develop experimental pellicles for the adhesion of the primary colonizing bacteria. Results Gt aqueous extracts exhibited better anti-plaque effect than Sp aqueous extracts. Their combination, equivalent to 1/4 and 1/2 of MIC values of Gt and Sp extracts respectively, showed synergistic anti-plaque properties with fractional inhibitory concentration (FIC) equal to 0.75. This combination was found to significantly reduce CSH (p < 0.05) and lower the adherence ability (p < 0.003) towards experimental pellicles. Conclusion Combination between Gt and Sp aqueous extracts exhibited synergistic anti-plaque activity, and could be used as a useful active agent to produce oral health care products

Evaluation of Salvadora persica L. and green tea anti-plaque effect: a randomized controlled crossover clinical trial

Background: In the author's earlier in vitro investigation, a combination of 0.25 mg/ml green tea and 7.82 mg/ml Salvadora persica L. aqueous extracts was found to exhibit significant synergistic anti-bacterial and anti-adherence effects against primary plaque colonizers biofilm. A clinical trial was needed to support these preliminary in vitro results and to investigate its efficacy as a mouthwash in the control of dental plaque. Methods: A 24 h plaque re-growth, double-blinded, randomized crossover trial was carried out. Participants (n = 14) randomly rinsed with test formulation, 0.12% chlorhexidine (control) and placebo mouthwashes for 24 h. A week before the trial, all participants received scaling, polishing and oral hygiene education. On the trial day, the participants received polishing at baseline and rinsed with 15 ml of randomly allocated mouthwash twice daily without oral hygiene measures. After 24 h, plaque index was scored and then the participants entered a 6-days washout period with regular oral hygiene measures. The same protocol was repeated for the next 2 mouthwashes. Results: The results were expressed as mean (±SD) plaque index. The test mouthwash (0.931 ± 0.372) significantly reduced plaque accumulation when compared with placebo (1.440 ± 0.498, p 0.0167). Conclusions: The test mouthwash has an anti-plaque effect for a 24 h period. Longer-term clinical studies are highly encouraged to investigate its anti-plaque effect for longer periods. Trial registration: This study was registered in ClinicalTrials.gov as NCT02624336in December 3, 2015

Characterization of carbonate rocks using seismic wave for tunnel design stability

The design and construction of a tunnel depends on the mechanical properties of the rock mass around the tunnel. Seismic method can be used to characterize the dynamic properties of rocks. The technique is mostly conducted in geophysical surveys and geotechnical investigations. The method utilizes reflected sound waves that can be used to describe the dynamic properties of rocks. Physical properties of carbonate rocks such as water content, density, hardness, permeability, porosity, wave velocity and abrasivity can be assessed and estimated using P-wave velocity. One of the important characteristics in rock is its ability to remain stable. In this research, seismic refraction survey was applied to measure the strength of carbonate rocks for tunnel stability design. The findings revealed that the regression between the primary velocity and the uniaxial compressive strength R2 was 0.8592, indicating that the rock was firm and solid. Observation by physical visual test showed that the rock samples with yellowish-grey and light grey colours were categorized in the weathering grade II and III, respectively. The results have concluded that the rocks in the proposed area met the full requirements for tunnelling construction. © The Authors, published by EDP Sciences

Resistin as potential biomarker for chronic periodontitis: A systematic review and meta-analysis

Objectives: To determine the serum and gingival crevicular fluid (GCF) levels of resistin between individuals with chronic periodontitis (CP) and those without CP, and to evaluate the role of resistin in CP. Materials and methods: The addressed focused question was "Is there a difference in the resistin levels between individuals with CP and those without CP?" four electronic databases: Medline, PubMed (National Institutes of Health, Bethesda), EMBASE, and Science direct databases from 1977 up to March 2016 for appropriate articles addressing the focused question. EMBASE and Medline were accessed using OVID interface which facilitated simultaneous search of text words, MeSH or Emtree. Unpublished studies (gray literature) were identified by searching the Open-GRAY database and references of the included studies (cross referencing) were performed to obtain new studies. In-vitro studies, animal studies, studies that reported levels of other cytokines but not resistin, letters to the editor and review papers were excluded. Results: Ten studies were included. Nine studies compared resistin levels between CP and periodontally healthy (H) individuals and reported higher mean serum and GCF levels of resistin in CP patients than the H controls. Two studies showed comparable resistin levels from GCF and serum between diabetes mellitus with CP (DMCP) and CP groups. Three studies included obese subjects and showed comparable serum and GCF resistin levels between obese subjects with CP (OBCP) and CP subjects. Conclusions: CP patients were presented with elevated levels of GCF or serum resistin as compared with H individuals. Resistin modulates inflammation in chronic periodontal disease and may be used as surrogate measure to identify subjects at risk for periodontitis. Resistin levels in patients with CP and systemic inflammatory disorders such as diabetes, obesity, or rheumatoid arthritis was not significantly higher than the levels in patients with only CP

Moving into a new era of periodontal genetic studies: relevance of large case-control samples using severe phenotypes for genome-wide association studies

Studies to elucidate the role of genetics as a risk factor for periodontal disease have gone through various phases. In the majority of cases, the initial 'hypothesis-dependent' candidate-gene polymorphism studies did not report valid genetic risk loci. Following a large-scale replication study, these initially positive results are believed to be caused by type 1 errors. However, susceptibility genes, such as CDKN2BAS (Cyclin Dependend KiNase 2B AntiSense RNA; alias ANRIL [ANtisense Rna In the Ink locus]), glycosyltransferase 6 domain containing 1 (GLT6D1) and cyclooxygenase 2 (COX2), have been reported as conclusive risk loci of periodontitis. The search for genetic risk factors accelerated with the advent of 'hypothesis-free' genome-wide association studies (GWAS). However, despite many different GWAS being performed for almost all human diseases, only three GWAS on periodontitis have been published - one reported genome-wide association of GLT6D1 with aggressive periodontitis (a severe phenotype of periodontitis), whereas the remaining two, which were performed on patients with chronic periodontitis, were not able to find significant associations. This review discusses the problems faced and the lessons learned from the search for genetic risk variants of periodontitis. Current and future strategies for identifying genetic variance in periodontitis, and the importance of planning a well-designed genetic study with large and sufficiently powered case-control samples of severe phenotypes, are also discussed.R. D. Vaithilingam, S. H. Safii, N. A. Baharuddin, C. C. Ng, S. C. Cheong, P. M. Bartold, A. S. Schaefer, B. G. Loo

Effect of nonsurgical periodontal treatment on clinical periodontal variables and salivary resistin levels in obese Asians

This study investigated changes in periodontal outcomes after nonsurgical periodontal treatment (NSPT) and evaluated associations of change in salivary resistin level with periodontal outcomes in obese Malaysians with chronic periodontitis. Sixty-two obese adults with chronic periodontitis were randomly divided into a test group (n = 31), which received NSPT, and a control group (n = 31), which received no treatment. Plaque score (PS), gingival bleeding index (GBI), probing pocket depth (PPD), and clinical attachment loss (CAL) were measured at baseline and at 6 and 12 weeks after NSPT. Salivary resistin levels were evaluated by using an enzyme-linked immunosorbent assay. PS was significantly lower in patients who received NSPT than in the control group at 6 and 12 weeks (P < 0.05). In the NSPT group the percentages of sites with shallow and moderate pockets decreased significantly, but there was no significant change in deep pockets. Resistin levels significantly decreased after NSPT (P < 0.05). Change in salivary resistin level was not significantly associated with periodontal outcomes. In obese Malaysians, NSPT significantly improved PS and GBI, and improved PPD and CAL for shallow and moderately deep pockets but not for deep pockets. Salivary resistin level was not associated with improvement in either periodontal variable