Mutans Streptococci Levels In Plaque Research Articles

Effect of chlorhexidine varnish application on mutans streptococci counts in orthodontic patients

Enamel demineralization occurs frequently around orthodontic brackets. High levels of mutans streptococci (MS) increase the risk of caries. The hypotheses tested in this study were that high-frequency application of 40% chlorhexidine varnish (40%CHX) results in lower levels of MS in plaque of orthodontic patients compared with low-frequency application, and that bimonthly application of 40%CHX results in lower levels of MS in plaque compared with 1% chlorhexidine/1% thymol varnish (1%CHX). Eighty adolescent patients were randomly allocated to 4 treatment groups: monthly, bimonthly, and quarterly 40%CHX application, and bimonthly application of 1%CHX. Plaque samples were collected monthly and processed for MS counts. Twenty patients dropped out before the evaluation time at 1 month. Data from the remaining 60 adolescents were analyzed by using linear regression models with the plaque bacterial ratio (PBRx) as the dependent variable. The trial was ended after 5 months because of a high number of dropouts. High-frequency application of 40%CHX did not provide lower mean PBRx than low-frequency application. Mean PBRx after 40%CHX application was lower than 1%CHX after 1 month (P = .002). This reduction was undiscernible 2 months after the application. 40%CHX application results in greater reduction of MS in plaque than 1%CHX a month after application. A follow-up study with a larger study population is warranted to test the first hypothesis.

Long-Term Effect of Xylitol Gum Use on Mutans Streptococci in Adults

Many studies have shown the effects of chewing xylitol gum on mutans streptococci (MS) over short- and long-term periods in children; however, few studies have addressed long-term periods in adults. The objective of this investigation was to examine for 6 months the effects of chewing xylitol gum on MS in saliva and plaque in 127 adults (mean age 28.0 years). The participants were assigned to three groups according to gum type, in part taking preference for flavor into account and in part at random: xylitol (XYL), maltitol (MAL) and control (CR); 33, 34 and 27 subjects in each group, respectively, completed the trial. Daily gum use of the XYL and MAL groups was 7.9 and 7.1 g, respectively. MS levels, which declined significantly in saliva (p < 0.05) and plaque (p < 0.001) in the XYL group after 6 months, exhibited a significant increase in plaque in the MAL group (p < 0.001). Differences in relative changes of MS levels in plaque during the experimental period were significant between the XYL group and the CR (p < 0.05) and MAL groups (p < 0.001). Differences in relative change of amount of plaque during the experimental period were not statistically significant between the groups. The present study demonstrated that chewing xylitol gum for 6 months continued to inhibit the growth of mutans streptococci in adults.

Linear response of mutans streptococci to increasing frequency of xylitol chewing gum use: a randomized controlled trial [ISRCTN43479664

BackgroundXylitol is a naturally occurring sugar substitute that has been shown to reduce the level of mutans streptococci in plaque and saliva and to reduce tooth decay. It has been suggested that the degree of reduction is dependent on both the amount and the frequency of xylitol consumption. For xylitol to be successfully and cost-effectively used in public health prevention strategies dosing and frequency guidelines should be established. This study determined the reduction in mutans streptococci levels in plaque and unstimulated saliva to increasing frequency of xylitol gum use at a fixed total daily dose of 10.32 g over five weeks.MethodsParticipants (n = 132) were randomized to either active groups (10.32 g xylitol/day) or a placebo control (9.828 g sorbitol and 0.7 g maltitol/day). All groups chewed 12 pieces of gum per day. The control group chewed 4 times/day and active groups chewed xylitol gum at a frequency of 2 times/day, 3 times/day, or 4 times/day. The 12 gum pieces were evenly divided into the frequency assigned to each group. Plaque and unstimulated saliva samples were taken at baseline and five-weeks and were cultured on modified Mitis Salivarius agar for mutans streptococci enumeration.ResultsThere were no significant differences in mutans streptococci level among the groups at baseline. At five-weeks, mutans streptococci levels in plaque and unstimulated saliva showed a linear reduction with increasing frequency of xylitol chewing gum use at the constant daily dose. Although the difference observed for the group that chewed xylitol 2 times/day was consistent with the linear model, the difference was not significant.ConclusionThere was a linear reduction in mutans streptococci levels in plaque and saliva with increasing frequency of xylitol gum use at a constant daily dose. Reduction at a consumption frequency of 2 times per day was small and consistent with the linear-response line but was not statistically significant.

Mutans Streptococci Dose Response to Xylitol Chewing Gum

Xylitol is promoted in caries-preventive strategies, yet its effective dose range is unclear. This study determined the dose-response of mutans streptococci in plaque and unstimulated saliva to xylitol gum. Participants (n = 132) were randomized: controls (G1) (sorbitol/maltitol), or combinations giving xylitol 3.44 g/day (G2), 6.88 g/day (G3), or 10.32 g/day (G4). Groups chewed 3 pellets/4 times/d. Samples were taken at baseline, 5 wks, and 6 mos, and were cultured on modified Mitis Salivarius agar for mutans streptococci and on blood agar for total culturable flora. At 5 wks, mutans streptococci levels in plaque were 10x lower than baseline in G3 and G4 (P = 0.007/0.003). There were no differences in saliva. At 6 mos, mutans streptococci in plaque for G3 and G4 remained 10x lower than baseline (P = 0.007/0.04). Saliva for G3 and G4 was lower than baseline by 8 to 9x (P = 0.011/0.038). Xylitol at 6.44 g/day and 10.32 g/day reduces mutans streptococci in plaque at 5 wks, and in plaque and unstimulated saliva at 6 mos. A plateau effect is suggested between 6.44 g and 10.32 g xylitol/day.

Validation and inter‐examiner agreement of mutans streptococci levels in plaque and saliva of 10‐year‐old children using simple chair‐side tests

Since there are few validation studies of chair‐side tests of oral mutans streptococci, we compared a commercially available strip test with the conventional laboratory assay. Two plaque samples obtained from the mesial surfaces of the upper right and lower left permanent molars of sixty‐five 10‐year‐old children (boys = 38, girls = 27) were cultured and incubated using chair‐side site strip tests (Dentocult SM, Orion Diagnostica). Two plaque sampling tools, namely dental floss and micro‐brush, were compared, and inter‐examiner agreement between recordings of three examiners was assessed. Paraffin‐stimulated saliva was then collected for laboratory and chair‐side assays. The plaque and saliva chair‐side tests correlated well with each other (Spearman rho, r=0.72) and with the laboratory method, showing coefficients of 0.76 and 0.80 for saliva and plaque, respectively. Compared to the laboratory method, the sensitivity (Sn), specificity (Sp), accuracy (A), and kappa (K) values of the salivary and plaque chair‐side tests were 0.63, 0.75 (Sn), 0.93, 0.90 (Sp), 0.82, 0.85 (A), and 0.58, 0.66 (K), respectively. Agreement between the two plaque sampling techniques was good (0.91). Inter‐examiner agreement of plaque scores ranged between 0.65 and 0.86 when all density categories were analysed separately; when dichotomized into low and high categories, complete agreement was found. Agreement between the plaque and saliva chair‐side tests and the laboratory salivary assay was good, and in terms of sensitivity, accuracy, and kappa values, the site strip plaque test surpassed the salivary chair‐side test.

Association of caries activity with the composition of dental plaque fluid.

This study tests the hypothesis that caries activity is associated with lower degrees of saturation with respect to enamel mineral in dental plaque fluid following sucrose exposure. Plaque fluids were obtained from caries-free, caries-positive, and caries-active subjects. Samples were collected before and at 3 and 7 min after a sucrose rinse on consecutive weeks and analyzed for organic acids, inorganic ions, pH, calcium activity, and, in selected samples, total protein. After sucrose, pH values were significantly lower in the caries-active group in comparison with the caries-free and caries-positive groups. Total and free calcium concentrations increased with decreasing pH, with free calcium being about one-third of total calcium. The caries-active group exhibited significantly lower degrees of saturation with respect to enamel mineral, after sucrose, and had significantly higher mutans streptococci levels in plaque than did the caries-free samples. Thus, saturation levels in post-sucrose plaque fluids reflect the cariogenic potential of dental plaque.