Acidogenicity Of Dental Plaque Research Articles

Clinical Assessment of a New Caries Activity Test Using Dental Plaque Acidogenicity in Children under Three Years of Age

The aim of this study was to assess the validity of a new caries activity test that uses dental plaque acidogenicity in children with deciduous dentition. Ninety-two children under the age of three years old underwent clinical examination using the dft index and examinations with two caries activity tests. Plaque samples for the new Cariview(®) test and the saliva sample for the conventional Dentocult SM(®) test were collected, incubated, and scored according to each manufacturers' instruction. The data were analysed using ANOVA and Spearman correlation analyses to evaluate the relationships between the test results and the caries experience. The mean dft index of all of the subjects was 4.73, and 17.4% of the subjects were caries-free. The levels of caries risk based on the new Cariview test score significantly increased with the caries experience (p < 0.01). The test results revealed a stronger correlation with caries indices (dft and dt index) than the conventional SM colony counting method (r = 0.43, r = 0.39, p < 0.01). The new caries activity test to analyse the acidogenic potential of whole microorganisms from dental plaques can be used to evaluate caries risk in children with deciduous teeth.

Correlation of Dental Plaque Acidogenicity and Acidurance with Caries Activity – Perspectives of the Ecological Plaque Hypothesis

AbstractThe ecological plaque hypothesis for the aetiopathogenesis of caries implies a microbial shift towards a more acidogenic and aciduric dental plaque microflora, due to a frequent carbohydrate intake. Certain plaque bacteria exhibit metabolic activity, at a low pH. A correlation exists between the increased numbers of some aciduric bacterial species, e.g. mutans streptococci and lactobacilli, and caries activity. The aim of this study was to study the acidogenic (lactate production / mg plaque x min., at pH 7.0) and aciduric potential (lactate production at pH 5.5 / lactate production at pH 7.0) of dental plaque in relation to the caries activity. Samples of dental plaque were collected from fifteen caries free and fifteen caries active children. Plaque suspensions in Ringer’s solution containing 1% sucrose and buffered with 0.5 M MOPS (pH 7.0) or MES (pH 5.5) were incubated aerobically at 37 ºC for 10-20 min. The production of lactic acid in the suspensions was determined by an enzymatic assay. In caries free children, significantly lower acidogenic potential at both pHs were recorded than in caries active children. The highest difference between the groups was in the acidogenic activity at neutral pH. On the contrary, the aciduric potential was lower in the caries active group than in the caries free. Caries activity correlated with the acidogenic potentials of dental plaque at both pH 7.0 and 5.5. A new perspective of the ecological plaque hypothesis based on the increased catabolic ability of plaque is proposed.

Correlation of Dental Plaque Acidogenicity and Acidurance with Caries Activity – Perspectives of the Ecological Plaque Hypothesis

Correlation of Dental Plaque Acidogenicity and Acidurance with Caries Activity – Perspectives of the Ecological Plaque Hypothesis

Assessing the clinical validity of a new caries activity test using dental plaque acidogenicity

Assessing the clinical validity of a new caries activity test using dental plaque acidogenicity

Lanthanum-containing hydroxyapatite coating on ultrafine-grained titanium by micro-arc oxidation: A promising strategy to enhance overall performance of titanium

Titanium is widely used in biomedical materials, particularly in dental implants, because of its excellent biocompatibility and mechanical characteristics. However, titanium implant failures still remain in some cases, varying with implantation sites and patients. Improving its overall performance is a major focus of dental implant research. Equal-channel angular pressing (ECAP) can result in ultrafine-grained titanium with superior mechanical properties and better biocompatibility, which significantly benefits dental implants, and without any harmful alloying elements. Lanthanum (La) can inhibit the acidogenicity of dental plaque and La-containing hydroxyapatite (La-HA) possesses a series of attractive properties, in contrast to La-free HA. Micro-arc oxidation (MAO) is a promising technology that can produce porous and firmly adherent hydroxyapatite (HA) coatings on titanium substrates. Therefore, we hypothesize that porous La-containing hydroxyapatite coatings with different La content (0.89%, 1.3% and 1.79%) can be prepared on ultrafine-grained (~200–400 nm) titanium by ECAP and MAO in electrolytic solution containing 0.2 mol/L calcium acetate, 0.02 mol/L β-glycerol phosphate disodium salt pentahydrate (β-GP), and lanthanum nitrate with different concentrations to further improve the overall performance of titanium, which are expected to have great potential in medical applications as a dental implant.

The Anticaries Effect of a Food Extract (Shiitake) in a Short-Term Clinical Study

The main objective was to investigate whether low-molecular-weight fraction of edible mushroom shiitake extract (Lentinus edodes) possesses caries-preventive properties. The study was designed as a double-blind, three-leg, cross-over, randomized, controlled clinical trial carried out on two series of volunteers at the University of Gothenburg, and the Academic Centre for Dentistry Amsterdam. Volunteers rinsed twice daily with a solution containing low-molecular-weight fraction of edible mushroom, placebo (negative control without active ingredients), or Meridol (positive control, AmF-SnF2) for two weeks, with a two-week washout period between each rinsing period. Changes in the acidogenicity of dental plaque before and after a sucrose challenge, shifts in microbial composition, and plaque scores were determined. Frequent rinses with shiitake reduced the metabolic activity of dental plaque. No reduction of plaque scores and no inhibition of the production of organic acids in plaque was found. Minor differences in microbial composition between test sessions were found. To conclude, the results indicate that shiitake extract has anticariogenic potential, but not to the same extent as the positive control.

Effects of mouthrinses containing essential oils and alcohol-free chlorhexidine on human plaque acidogenicity

The aim of this in vivo study was to evaluate the effect of two antimicrobial mouthrinses on dental plaque acidogenicity after a sucrose challenge. Twenty subjects, with a mean age of 59 years, participated in a double-blind intraindividual randomized study. Three mouthrinses were used in 16-day rinsing periods in addition to their regular mechanical oral hygiene: a solution with essential oils (EO), solution with alcohol-free chlorhexidine (CHX) and water (negative control). The three test periods were separated by 3-month washout periods. Changes in plaque acidogenicity were evaluated after a sucrose challenge at day 0 (baseline) and at day 17 of each mouthrinse period using the microtouch method. Both CHX and EO resulted at day 17 in statistically significant less attenuated pH falls compared to the water rinse. The CHX mouthrinse resulted in the least pronounced pH values compared with EO (ns) during the whole 30-min period. When calculated as area under the curve (AUC), significantly lower values (AUC(6.2) ) were found for CHX and EO at day 17 compared to day 0. A significant difference for AUC(6.2) between CHX and water was found at day 17. No statistically significant differences were found for any of the comparisons with AUC(5.7). The results from this study indicate that both the essential oils and the alcohol-free chlorhexidine reduced plaque acidogenicity after a sucrose challenge. Large interindividual variations were observed.

Plaque formation and lactic acid production after the use of amine fluoride/stannous fluoride mouthrinse

The aim of this study was to determine the effects of 3 wk of daily rinsing with amine fluoride/stannous fluoride (AmF/SnF(2)) mouthrinse on plaque formation at buccal and interproximal sites, and on the acid production in plaque, in a randomized clinical trial with 30 participants. The amount of plaque was scored according to Turesky's modification of the Quigley and Hein index. Plaque samples were collected, before and after sucrose rinsing, from the buccal and interproximal surfaces of upper (pre)molars at two baseline visits and on days 2 and 7 after the discontinuation of 3 wk of daily rinsing. Metabolic acid ions were determined by capillary electrophoresis. The results at baseline showed higher lactic acid concentrations in resting interproximal plaque than in buccal plaque, and a higher acid production in response to sucrose challenge in buccal plaque than in interproximal plaque. After 3 wk of use of the AmF/SnF(2) mouthrinse, no significant differences in plaque scores were observed, and the alleged reduction in acidogenicity of dental plaque was not significant on the second day after the last mouthrinse. We conclude that 3 wk of use of AmF/SnF(2) rinse once daily does not result in a reduction of plaque formation or in a reduction of sucrose metabolism in buccal and interproximal plaque after discontinuing the rinse.

Effect of White Cheese and Sugarless Yoghurt on Dental Plaque Acidogenicity

White cheese and sugarless yoghurt are frequently consumed traditional Turkish foods. The aim of this study was to assess their acidogenic potential when eaten alone or following a rinse with sucrose solution. Plaque pH was measured by a pH microelectrode at baseline to determine the resting plaque pH and at time intervals of 1–60 min after rinsing with 10% sucrose solution or eating the test food for 1 min. White cheese consumption for 1 min increased the plaque pH. When white cheese was eaten 5 min after rinsing with 10% sucrose solution, the plaque pH rose rapidly. After sugarless yoghurt consumption, the pH fell to a similar minimum as for sucrose after 5 min but returned to baseline levels after 30 instead of 60 min. Consumption of sugarless yoghurt after a sucrose rinse initially reduced the plaque pH further but did not affect the time taken for pH to regain baseline levels.

First molar eruption related to plaque acidogenicity in children of different socio-economic status

Objective. The aim of this study was to evaluate the association between the eruption stage of the lower first permanent molar and dental plaque acidogenicity. Socio-economic status (SES), gender, and oral hygiene condition were also variables considered. Material and methods. 230 children between 6 and 8 years of age were recruited from one public and one private primary school with different SES in Lima, Peru. Clinical examinations were performed to assess lower first permanent molar eruption stage, plaque acidogenicity, and oral hygiene condition. Bivariate associations were analyzed through chi-square tests and the variable interactions were analyzed through a hierarchical log-linear analysis with backward elimination. Results. 21.8% of the population had highly acidogenic plaque, 34.3% acidogenic plaque, and 43.9% non-acidogenic plaque. Of the lower first permanent molars, 46.1% were fully erupted, whereas 53.9% were partially erupted. According to the final log-linear model, children with fully erupted molars and non-acidogenic plaque are less frequent in low than in high SES. Also, the frequency of children with partially erupted molars and acidogenic to highly acidogenic plaque is higher in males than in females. Finally, fully erupted molars and non-acidogenic plaque are more frequent in children with good hygiene than in children with moderate to poor hygiene. Conclusions. Association between eruption stage of the lower first permanent molar and plaque acidogenicity was not significant in a bivariate context. However, in a multivariate context, socio-economic status, oral hygiene condition, and gender had an impact on the association between the two main variables.

The Effect of a Single Application of 40% Chlorhexidine Varnish on the Numbers of Salivary Mutans Streptococci and Acidogenicity of Dental Plaque

The relationship between the numbers of salivary mutans streptococci and the acid production in dental plaque after a single application of the 40% chlorhexidine varnish EC40^® has been studied. Thirteen healthy subjects were treated with EC40 varnish. Saliva samples were taken before and up to 12 weeks after treatment to count mutans streptococci and lactobacilli. At the same time points plaque samples were taken before and after sucrose challenge and analyzed for protein and organic acid. Suppression of salivary mutans streptococci was observed together with a reduced production of lactic acid in sucrose-challenged dental plaque in 9 subjects while inhibition of acid production without significant suppression of mutans streptococci was observed in the other 4 participants. The duration of the effects differed among the individuals but never exceeded 6 weeks. We conclude that a prolonged suppression of mutans streptococci and acid production was not achieved by a single treatment with EC40 varnish in all subjects. Moreover, reduced acidogenicity of dental plaque after chlorhexidine treatment was not necessarily predicted by suppression of mutans streptococci in saliva.

Evaluation of the Cariogenic Potential of Cassava Flours from the Amazonian Region

Cassava flour is the main dietary carbohydrate source in the Amazonian region. The cariogenic potentials of the two main kinds of cassava flour – ‘seca’ and ‘d’água’ – were evaluated in vivo and in vitro. A sweet made from a regional fruit (cupuaçú) and a species of local fish (tambaqui) were used as positive and negative controls, respectively. For in vivo evaluation of dental plaque acidogenicity, the study had a crossover design, in four legs, with 19 volunteers in four treatment groups. Dental plaque pH was determined by the microtouch method before and for 60 min after food consumption. For in vitro evaluation, stimulated saliva of each volunteer was incubated with the food and pH variation was determined over 4 h. Carbohydrates were chemically determined in the flours and the majority was found to be water-insoluble. In vivo, plaque pH decreased significantly after the consumption of the sweet (p < 0.05), increased after the fish (p < 0.05), but did not change after intake of the flours (p > 0.05). In vitro, the flours were slowly fermented by bacteria present in saliva. The in vivo and in vitro findings suggest that, in the form that the main cassava flours from the Amazonian region of Brazil are customarily eaten, they may be considered to have no or very low cariogenicity.

Effects of Chlorhexidine-Fluoride Mouthrinses on Viability, Acidogenic Potential, and Glycolytic Profile of Established Dental Plaque

Inhibition of dental plaque acidogenicity by chlorhexidine (CHX) mouthrinses has been ascribed to a long-lasting bacteriostatic effect due to binding of CHX to oral surface structures combined with a slow release rate from the binding sites. The present aims were to study the effects of CHX-containing mouthrinses on the viability and glycolytic activity of established plaque in order to assess the bactericidal versus the bacteriostatic effects. Following 2 days of plaque accumulation, three groups of 10 students rinsed with either 12.0 mM NaF, 0.55 mM CHX plus NaF, or with 2.2 mM CHX plus NaF. Plaque samples were collected before and 90 min after mouthrinsing. The pH in pooled pre- and post-rinse plaque samples was recorded before and up to 10 min after the addition of D-[U-14C]glucose. Total colony-forming units in each sample were determined. High-performance liquid chromatography analyses showed lactate to be the major extracellular glycolytic metabolite in all samples. CHX-NaF markedly reduced the colony-forming units, the pH fall from fermentation of glucose, as well as glucose consumption and lactate formation, whereas NaF alone exhibited no such effects. The reduction of glucose consumption by the CHX-NaF mouthrinses corresponded to the reduction of colony-forming units, indicating no bacteriostatic effect. The plaque pH in vivo was monitored in each student 90 min after mouthrinsing with the test solutions prior to and up to 1 h after a sucrose mouthrinse using touch microelectrodes. The CHX-NaF mouthrinses reduced the fall in pH significantly (p < 0.05) as compared with the NaF mouthrinse.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of mastication on saliva, plaque pH and masseter muscle activity in man

An earlier study showed that frequent gum chewing may enhance parotid gland function and reduce the acidogenicity of dental plaque. The aim now was to determine whether these effects would be observed after a 2-week period of diet altered to increase masticatory effort, and secondarily to assess the effects of chewing gum on masseter muscle activity. Ten subjects took part in the first experiment. Saliva was collected before and after the diet change and the plaque pH response to a sucrose challenge was measured. Subjects completed 3-day diet histories and wore electromyographic (EMG) devices to record masseter activity. In the second experiment, 10 subjects wore EMG devices for 3 days to record masseter activity on three daily regimens: baseline (no gum chewing), hourly gum chewing (sugar-free gum chewed for 10 min every hour) and chewing five sticks of gum each for 20 min during the day. Data were analysed by paired t test or repeated-measures analysis of variance. For the first experiment, EMG data indicated significant increases in chewing activity ( p < 0.05), although there were no changes in salivary flow rates or the plaque pH response to sucrose. The second experiment showed that total EMG activity increased significantly on both gum-chewing regimens ( p < 0.01), the magnitude of the increase being greater for hourly chewing. Overall, masseter EMG activity was increased 41% by diet alteration, compared to increases of 96 and 152% on the five-stick and hourly gum-chewing regimens, respectively.

The Effect of Increased Mastication by Daily Gum-chewing on Salivary Gland Output and Dental Plaque Acidogenicity

The effect of increased mastication on plaque metabolism and salivary gland function was determined in 11 human subjects who chewed a sugarless gum for ten minutes of each waking hour for two weeks. Prior to and at the conclusion of the gum-chewing regimen, unstimulated whole saliva and 2% citric-acid-stimulated parotid saliva were collected. Flow rates, pH, and buffer capacity were determined on all saliva samples. In addition, parotid saliva was analyzed for protein concentration and the proteins further studied by SDS-PAGE. The plaque pH response to a 10% sucrose rinse was also measured before and after the regimen. Significant increases were observed in the pH and buffer capacity of unstimulated whole saliva as were similar increases in the flow rate, pH, and buffer capacity of stimulated parotid saliva. Protein concentrations and profiles remained unaffected. In addition, the resting plaque pH and minimum plaque pH reached after a sucrose challenge were both raised significantly, with a significant reduction in the cH area. The results of this study indicate that increased masticatory effort by frequent consumption of sugar-free chewing gum over a prolonged time period resulted in a functional increase in the output of stimulated parotid saliva, as well as in increases in pH and buffer capacity of whole and parotid saliva, which may help to reduce plaque acidogenicity.

The Antimicrobial Action of Fluoride and its Role in Caries Inhibition

Despite a considerable amount of literature on the effects of fluoride in dental plaque, several urgent questions remain unanswered, such as: Does the inhibiting effect of fluoride on dental plaque metabolism contribute to caries prevention? Does adaptation of plaque to fluoride affect its cariogenicity? Single applications of fluoride directly to dental plaque reduced acid production. Also, fluoride dissolving from topically treated enamel reduced the acid production in covering layers of oral bacteria in vitro. The effects of both treatments were only of short duration and may not be relevant to caries prevention in vivo. In contrast, daily applications of fluoride resulted in a reduction of the acidogenicity of dental plaque even 8-12 h after the treatment. Such a reduction is likely to contribute to caries prevention. But it has to be realized that when plaque reaches saturation with respect to fluoridated calcium (phosphate) precipitates, enamel becomes insoluble and any antimicrobial effect becomes irrelevant. Still lacking are data on the antimicrobial effects of fluoride regimens normally used in home care, in weekly rinsing programs in schools, or treatments applied professionally every six months. Adaptation of Streptococcus mutans to fluoride has been suggested to reduce the cariogenic potential of the cells. In vitro-induced fluoride-resistant strains were less cariogenic in rats, and the velocity of acid production in vitro was reduced at constant pH greater than 5.5. Despite the ability of oral bacteria to adapt to fluoride, evidence of adaptation in dental plaque of normal subjects resulting in a reduced cariogenic potential has not yet been demonstrated.

The effect of salivary clearance of sucrose and fluoride on human dental plaque acidogenicity

Ten subjects rinsed with a 20% (0.58 M) sucrose solution with or without 0.2% NaF (905 parts/10 6 F −) added in two separate experiments. Saliva and plaque were collected before rinsing and after 2, 5, 10 and 30 min. Sucrose and fluoride concentrations in saliva and acid anion and fluoride concentrations in plaque were analysed. There was a statistically significant and positive correlation between the concentration of sucrose in the saliva 2 min after the rinse and the subsequent concentrations of lactate in plaque at 10 and 30 min after the rinse with sucrose alone but not in the presence of fluoride. Salivary fluoride concentrations during 2–30 min after the sucrose rinse were significantly correlated with plaque fluoride concentrations during the same time. The addition of fluoride to the sucrose rinse significantly inhibited lactate production.

Effect of fluoride and non‐fluoride salts of copper, silver and tin on the acidogenicity of dental plaque in vivo

The aim of the present study was to assess the relative importance of the metal and fluoride components in the inhibiting effect on the acidogenicity of plaque exhibited by silver fluoride and copper fluoride. The effect of these salts was therefore compared with that of silver nitrate and copper sulfate. Four subjects with a 3-day-old sucrose induced plaque received topical application of the test agents. Plaque pH-measurements, in the presence of sucrose, were performed prior to and at given time intervals after this application. No significant differences were observed in the inhibitory effect of 5 mM solutions of the copper and silver salts. These salts were all more effective than stannous fluoride in the first 4 h following application. Sodium fluoride was the least effective. All metals tested were found to be retained in plaque. The inhibitory activity appears to be carried by the cations. Other properties than retention alone may explain the higher effectiveness observed for silver and copper.

Thiol groups and reduced acidogenicity of dental plaque in the presence of metal ions in vivo.

Metal ions are known to influence the cariogenicity of dental plaque. Inhibition of acid metabolism in plaque may be of importance in this respect. Metal ions inhibit the acidogenicity of dental plaque to a different extent and it has been suggested that an enzyme inhibition based on oxidation of thiol groups may explain this observation. The aim of the present study was to evaluate the significance of oxidation of thiol groups in the inhibition of acid production in plaque by silver, tin and zinc salts. Nine subjects with 3-d sucrose induced plaque received topical applications of the metal ions. Cysteine or glutathione, which are known to reverse thiol oxidations, were then applied in one side of the mouth. Plaque pH measurements, in the presence of sucrose, were performed prior to and up to 2 h after treatment. The results showed that the acid production inhibited by the metal ions was reactivated by cysteine or glutathione. Iodoacetamide and p-chloromercuribenzoate were also shown to inhibit acid formation in dental plaque. The high affinity silver, tin and zinc have for SH groups, the observed inhibitory effect of these metals, the reactivation of the metabolism by monothiols and the fact that organic sulfhydryl reagents inhibit acid formation in plaque indicate that oxidation of thiol groups may be the mechanism by which these metals exert their effect.

Effect of Some Polyvalent Cations on the Acidogenicity of Dental Plaque in vivo

The effect of different metal ions on the acidogenicity of dental plaque was investigated. It was found that mouthrinsing with 20 mM solutions of SnF2, ZnCl2, AlCl3 and FeCl3 inhibited the metabolic activity of dental plaque for periods up to several hours, whereas the same concentration of MgCl2 showed no such effect but on the contrary tended to increase the acid-formation potential. Sodium chloride (40 mM) had no measurable effect.