Drop In Plaque pH Research Articles

ヒト歯垢ｐＨ測定によるパラチノースおよびマルチトール使用チューインガムの酸産生能の評価

The purpose of this study was to evaluate acidogenicity of chewing gum sweetened with palatinose or/and maltitol in pH-response of dental plaque.The subjects of six volunteers, four males and two females, aged 23 to 31 year, were participated in this study. An IS-FET pH electrode was used to monitor changes in plaque pH on the buccal site of the mandibular fist molar. Plaque pH was measured in the utilization of plaque which had accumulated on the electrodes for four days. Chewing gum was tested individually and subjects had consumed only water for two hours before measurement. The gum was chewed for 4 minutes and then taken out. The pH measurement was performed for 30 minutes. Unstimulated salivary secretion rate and salivary secretion rate stimulated by the chewing gum were measured by Curby cup. Salivary mutans streptococci level was scored by the semi-quantitative method. A paired t test, ANOVA, multiple range test, t test (LSD), Tukey's studentized range (HSD) test were performed for six variables: Minimum pH, ΔpH, maximum rate of pH drop, maximum H+, total H+, and maximum rate of H+ production. Repeated measures analysis were performed for the pH-values, at 0 to 10, 15, 20, and 30 minutes. The same statistical analysis was performed for H+.Individual variation of plaque pH-response after chewing of the test gum was observed. Values of minimum pH for palatinose or/and maltitol chewing gum were significantly higher than for sucrose chewing gum and did not drop below pH 6.0 (p<0.0001). The other two variables were significantly lower than in sucrose chewing gum (p<0.0001). Plaque pH-values at 3 to 30 minutes for palatinose or/and maltitol-chewing gum were significantly higher than for sucrose chewing gum (p<0.001). Similar findings were obtained by using maximum rate of H+. production. Mutans streptococci level was partially associated with plaque pH drop, but there was no correlation between salivary secretion rate and three different pH variables.The findings indicate that chewing gum sweetened with palatinose or/and maltitol is non-cariogenic. Individual variation might be explained by mutans streptococci level and salivary factors such as buffering capacity.

Effect of Dental Plaque Age and Bacterial Composition on the pH of Artificial Fissures in Human Volunteers

Changes in sucrose-induced plaque pH profiles and the microbial composition of occlusal tooth surface fissures were analyzed using wire telemetry and bacterial culturing techniques. Four human volunteers wore appliances containing artificial fissures constructed with ion-sensitive field-effect transistor (ISFET) electrodes for 1, 2 and 4 days; 1 subject kept the electrode for 3 weeks. After monitoring the plaque pH response at the base of the fissure to a 10% (w/v) sucrose rinse the plaque was removed and analyzed for total viable bacteria, total and specific streptococci, lactobacilli and Actinomyces spp. One-day-old plaque showed a rapid drop in plaque pH to a minimum of 4.8 +/- 0.2, with 2-day-old plaque showing the most acidogenic pH profile (minimum pH 4.6 +/- 0.2). The 4-day-old plaque response was less acidogenic (minimum pH 5.0 +/- 0.3) than the results from days 1 and 2. Responses from 13- and 21-day-old fissure plaques showed greatly decreased acidogenic responses (day 21 minimum pH 5.7). Viable bacteria recovered from the fissure increased from approximately 4 x 10(6) colony-forming units on day 1 to 1.2 x 10(7) on days 2 and 4 and 1.7 x 10(7) on day 21. Streptococci (greater than 50%) and Actinomyces (greater than 10%) dominated in the fissure plaques and their levels were related to minimum pH. Since fissure plaque of all ages tested contained high concentrations of acidogenic bacteria, the decreased acidogenic response at the base of fissures with increasing plaque age suggests that maturing fissure plaques provide an increasingly greater diffusion barrier to fermentable carbohydrates.

Effects of variously processed starch on pH of human dental plaque.

The aim of this investigation was to study the effect of starch in various cereal products on pH of human dental plaque in vivo as compared to availability to the alpha-amylase of starch in vitro. Three separate experimental series were performed including: 1) rye and wheat products, 2) wheat products processed under both mild and severe conditions, and 3) wheat products with and without added sucrose. The pH drop in dental plaque was studied after a mouthrinse in groups of 10 subjects. Solutions of glucose or sucrose were used as references. No differences were found between boiled rye and boiled wheat, nor between rye bread and wheat bread. Severely popped wheat resulted in the greatest pH drop, followed, in order, by drum-dried and extrusion-cooked products. Mildly steam-flaked and mildly dry-autoclaved products induced comparable small pH falls. Sucrose-sweetened wheat products resulted in lower plaque pH values compared to unsweetened products. This effect was most pronounced with a mildly processed sample. In all three series, the glucose and sucrose reference solutions showed the greatest pH drop. In conclusion, all processing methods increased the fermentability of starch in human dental plaque in vivo. Thus, the more severe the processing conditions the more prominent the pH falls. The pH drop in plaque in vivo correlated (r = 0.96 in Series 1 and r = 0.92 in Series 2) with the rate of starch hydrolysis with alpha-amylase in vitro.

Effects of rinses with an acidic calcium phosphate solution on fluoride uptake, caries, and in situ plaque pH in rats.

The effects of oral rinses on enamel fluoride uptake, caries, and plaque pH in rats were investigated by use of (1) an acidic calcium phosphate solution (CPS) saturated with dicalcium phosphate dihydrate (DCPD) and (2) a 1% fluoride solution. Osborne-Mendel rats, 19 days of age, were randomly assigned to one of four mouth-rinse treatment groups, with the two consecutively administered rinses being: H2O-H2O; H2O-F; CPS-H2O; and CPS-F. The treatments were administered on days 1 through 4, and the animals were provided with a cariogenic challenge throughout the study. The groups treated with F exhibited significantly higher mean levels of enamel-bound F than did the non-F groups. Furthermore, CPS significantly increased uptake of F by enamel when used as an adjunct to the F treatment. The caries scores of the CPS-F and H2O-F groups were not statistically different; however, a strong negative correlation was observed between enamel F content and caries scores, indicating that as more F was incorporated into the teeth, less caries formation occurred. Despite the significant differences in enamel F and caries scores among some of the treatment groups, post mortem in situ plaque pH drop in response to a sucrose rinse showed no differences among these groups.

Exchange of fluoride between bovine enamel and the surface-related cells of the oral bacterium Streptococcus mutans

Standard areas of intact bovine enamel surface were fluoridated with dental F-varnish for 24 h and then cleaned from varnish residues and thoroughly rinsed with distilled water. Sucrose fermentation by a plaque-like layer of Streptococcus mutans cells covering such an enamel surface was accompanied by a rapid but transient accumulation of F of enamel origin by the Strep. mutans cells and by a pH drop in the plaque to pH 4.0. The uptake of F from the surface by the control cells, utilizing their carbohydrate stores and causing a smaller pH-drop, was slow but no release of F back to the cell exterior took place within 18 h. In a second experiment, F-varnished and placebo-varnished bovine enamel granules were used as above, but they were not thoroughly washed after being varnish-treated and cleaned. Both the sucrose-fermenting and the control layer of Strep. mutans rapidly released appreciable but equal amounts of fluoride from the F-treated enamel. The accumulation of F of enamel origin by the Strep. mutans cells with or without sucrose was rapid and of almost the same magnitude. In the model with the sucrose-utilizing Strep. mutans and the F-treated enamel granules, the plaque pH-drop was less and the dissolution of the enamel Ca and P completely prevented compared to the respective changes in the sucrose-utilizing model with placebo-treated enamel granules.