The effect of different milk formulas on dental plaque pH

OBJECTIVES: The purposes of this study were (1) to investigate the effect of different milk formulas on dental plaque pH after rinsing with these three categories, type of protein-based formulas (milk-based, soy-based, protein hydrolysate), type of sugar (only lactose, lactose and other sugars, only non-milk extrinsic sugars), and casein ratio (high and low casein), and (2) to observe organic acids formed by different milk formulas. METHODS: Baseline plaque pH and plaque pH at 2, 5, 10, 15, 20, 25, 30, and 60 min after rinsing with milk formulas were recorded by a combination electrode in 14 healthy subjects. Deionized water and 10% sucrose were used as a negative and positive control. The plaque sample was also analysed to identify and quantify the organic acids using a high-performance liquid chromatography. Parameters including minimum pH, maximum pH drop, and area under curve were compared by RMANOVA and paired t-test. RESULTS: The minimum pH was not significantly different among different protein-based formulas, whereas, the maximum plaque pH drop of soy-based and milk-based formula was significantly higher than that produced by protein hydrolysate formula (P=0.022 and 0.03, respectively). Area under curve produced by soy-based and milk-based formulas was significantly larger than that created by protein hydrolysate formula (P=0.025 and<0.001, respectively). Milk formulas containing only lactose caused significantly less plaque pH change in minimum pH (P<0.001), maximum pH drop (P=0.003), and area under curve (P<0.001) when compared with formulas containing lactose and other sugar but not with special formulas containing only non-milk extrinsic sugar. Similarly, special formulas containing non-milk extrinsic sugar produced significantly lower minimum pH and smaller area under curve than formulas containing lactose and other sugar did (P=0.044 and 0.009, respectively). No different results were found between high and low casein follow-on formulas. Lactic acid was produced more by rinsing with formulas containing lactose and other sugars than that produced by formulas containing only lactose. CONCLUSIONS: This study suggests that milk formulas containing added other sugars tend to cause a decrease in plaque pH.     

Dental plaque as a biofilm: a pilot study of the effects of nutrients on plaque pH and dentin demineralization

Direct or in situ methods (e.g., confocal microscopy, microsensors) are used to study non-oral biofilms for almost two decades, and they have recently been introduced in the research of dental plaque. We combined a pH microsensor technique and transversal microradiography (TMR) in a pilot study where the effects of nutrient availability on plaque acidogenicity and on the development of caries-like lesions were assessed. One volunteer accumulated dental plaque for 7 days in 0.2-mm-wide and 0.8-mm-deep dentin grooves at four conditions: (1) saliva only, (2) 8 x 5 min/day dipping in 10% sucrose solution, (3) 7 x 5 min/day consumption of sweet cookies plus one meal/day, and (4) subject's regular diet. Plaque pH versus time and depth profiles in the grooves were recorded ex vivo before and after sugar challenge. 'Saliva' plaque responded to sugar with slow pH decrease--minimum pH 5.6-5.8 was reached after 30 min, while sugar dipping resulted in metabolically active plaque (minimum pH 5.3-5.5 within 4-8 min). TMR analysis revealed no demineralization after these two periods. Metabolically active plaque leading to distinct lesions resulted from frequent plaque exposure to diets rich in starch and carbohydrates (groups 3 and 4). These findings strengthen the view that the plaque acidogenicity does not necessarily reflect cariogenicity, and that retention of food components may account for increased cariogenicity at plaque retention sites in the mouth.     

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.     

A study of influence of sugars on the modulations of dental plaque pH in children with rampant caries, moderate caries and no caries

The present study is undertaken to find out the pH of resting plaque in children with no caries, moderate caries and rampant caries and to determine the modulations of plaque pH with different sugar solution rinses viz: sucrose, glucose and fructose. The study was carried out on forty five children, in the age group of 3-10 years (25 males and 20 females). The child was given 10 ml of test solution and was asked to rinse and swish it in the mouth for a period of 30 sec. Plaque samples were taken from 20 different spots after 5, 10, 20 and 30 min of the rinse and pH values of all the samples were determined. Results show that there was a statistically significant (P<0.05) difference between the pH values of plaque at different intervals of time with sucrose, fructose and glucose solution rinse in children with moderate caries, rampant caries as compared to the caries free group. Sucrose was found to be highly cariogenic in all the children with a greater potentiating effect in moderate and rampant caries. Glucose also appeared to have a cariogenic role while fructose had the least of it all.     

Effect on plaque pH of fruit drinks with reduced carbohydrate content.

OBJECTIVES: To assess the acidogenic response in dental plaque after challenge with four fruit drinks, including two blackcurrant drinks newly formulated, with low levels of carbohydrate. METHODS: 24 adult volunteers rinsed, in randomised order, with each of two new formulations of a blackcurrant drink (7% juice with 0.49% and 10% juice with 0.65% carbohydrate concentration respectively), an apple and blackcurrant drink with no added sugar (0.8%), and a mixed citrus fruit drink with a higher carbohydrate concentration (4.5% w/v). Solutions of 10% sucrose and 10% sorbitol were used as controls. Plaque pH was assessed, in vivo, before and after the acidogenic challenge using the plaque-harvesting technique. RESULTS: Results showed that the minimum plaque pH after the subjects rinsed with the new blackcurrant drinks was higher as compared with all the other test products and significantly so compared with the mixed citrus drink (P = 0.0001). It was also found that with the 7% blackcurrant juice drink none of the subjects and with 10% blackcurrant juice drink only one subject recorded a pH drop below the pH of 5.7. Ten minutes after consumption, both the new formulation blackcurrant drinks produced significantly higher plaque pH than the mixed citrus drink. In addition, overall change in the hydrogen ion concentration over the study period (sigma delta cH) was significantly less with both new blackcurrant drinks compared with the mixed citrus drink. CONCLUSIONS: It was concluded that the two new formulations with low levels of carbohydrate had a low acidogenic potential and did not depress the plaque pH below the critical level and their consumption could not be considered to pose a significant risk for enamel demineralisation.     

Acidogenic potential of Soya infant formula in comparison with regular infant formula and bovine milk: a plaque pH study

Soya infant formulas are essential for infants intolerant to cow's milk. Soya formulas contains glucose syrup or maltodextrins instead of Lactose, which has led to concern that they are potentially more cariogenic than standard infant formulas containing lactose. The study was conducted to compare the acidogenic effect of Soya Infant formula, infant formula and bovine milk. The study group consisted of 75 children in the age group of 7-10 years. The plaque pH was measured using plaque pH meter, before and after rinsing with different samples for sixty minutes Soya infant formula is found to be more acidogenic than infant formula (with lactose) and bovine milk. This study demonstrates high caries inducing potential of Soya infant formula. Further awareness of the possible role of Soya infant formula in early childhood caries is required.     

Low-cariogenicity of trehalose as a substrate

Objectives: The effects of trehalose on cariogenesis by mutans streptococci were investigated.

Methods: Inhibited effect of trehalose on water-insoluble glucan (WIG) synthesis from sucrose by glucosyltransferase (GTase) of mutans streptococci was assayed. The acid fermentability of trehalose by mutans streptococci was determined by the measurements of pH, and amounts of lactic acid production. Plaque pH was determined by the measurements of collected plaque from volunteers after sugar mouth-rinse. Rat experimental caries was investigated by feeding a sucrose and/or trehalose diet.

Results: Trehalose was not utilized as a substrate for GTase. In addition, trehalose inhibited synthesis of WIG by GTase in the presence of sucrose. Trehalose showed weaker and slower acid fermentation than sucrose by mutans streptococci. The levels of lactic acid production from trehalose by Streptococcus mutans and Streptococcus sobrinus were 24.2 and 59.8% of those from sucrose, respectively. The minimum plaque pH after sucrose mouth-rinse was lower than those after trehalose mouth-rinse in all subjects. Plaque pH after trehalose mouth-rinse never reached critical pH. The substitution of trehalose for sucrose in the rat diet significantly reduced caries scores. Furthermore, rats fed diets containing sucrose and trehalose had significantly lower caries scores than those fed a sucrose diet.

Conclusions: These results suggested that trehalose might be not only lowly cariogenic but also anti-cariogenic, and is promising as a sugar substitute.     

Effect of nonfluoridated milk and fluoridated milk on acidic dental plaque

PurposeRecovering the acidic plaque pH to its resting value as soon as possible after exposure to a sugary beverage might reduce the risk of dental caries. Milk contains nutrients that help to buffer acid. Adding fluoride to milk might enhance this effect. Accordingly, this study investigates the effect of milk and fluoridated milk on acidic dental plaque.MethodsThe study was a randomized crossover design. Ten subjects were asked to rinse for 2 min with the following solutions: (1) water, (2) 10% sucrose, (3) milk, (4) fluoridated milk, (5) 10% sucrose followed by water, (6) 10% sucrose followed by milk, or (7) 10% sucrose followed by fluoridated milk. The supra-gingival plaque was collected before rinsing and every 5 min after rinsing to measure the plaque pH.ResultsThe results showed that rinsing with 10% sucrose caused acidic dental plaque. After rinsing with 10% sucrose followed by milk, fluoridated milk, or water, the maximum plaque pH dropped and the area under the curve was significantly less than that after rinsing with 10% sucrose alone (p = 0.001). The maximum change in the plaque pH and the area under the curve in the group challenged with 10% sucrose followed by fluoridated milk were significantly lower than those in the group followed by nonfluoridated milk (p = 0.04).ConclusionRinsing with milk could raise the acidic plaque pH to the resting value faster than individual's natural capacity to do so. Adding fluoride to milk can enhance this effect.     

Enamel microhardness change and plaque pH measurements in an intra-oral model in humans

Changes in plaque pH and microhardness of bovine enamel slabs were evaluated with a seven-day intra-oral cariogenicity test (ICT). The test enamel slabs were mounted in prosthetic appliances with a Dacron mesh cover for enhancement of microbial colonization. Three percent solutions of sucrose, sorbitol, and xylitol were evaluated as four daily extra-oral immersions of 10 min each, for seven days, and the results were compared with baseline experiments (no daily immersions). The pH was measured with antimony electrodes on one-day and seven-day ICT plaque samples that were challenged with a one-minute immersion in the studied substrates. Plaque samples in the baseline experiments were challenged with 3% sucrose. The enamel softening was assessed with measurements of microhardness. Sucrose challenge caused pH depression with both the baseline and the sucrose-immersed plaque. Sorbitol and xylitol challenge did not depress the plaque pH. Compared with the baseline, sucrose immersions caused enamel softening; sorbitol and xylitol did not.     

Inhibition of acid production in dental plaque bacteria by green tea catechins

The inhibition of acid production from dental plaque and mutans streptococci by epigallocatechin gallate (EGCg), one of the green tea catechins, was examined. The effect of EGCg solution on dental plaque pH was investigated.Subjects rinsed their mouths with 2 mg/ml EGCg solution and then, after 30-min interval, rinsed their mouths with 10% sucrose. Plaque samples were collected at appropriate times and the pH was measured. The pH values of plaque samples from 15 volunteers were significantly higher after treatment with catechin than after treatment with water. EGCg inhibited pH fall when cariogenic bacteria grown in medium with or without sucrose were incubated with sugar. In medium without sucrose, cultured cells were killed time-dependently by EGCg treatment. However, EGCg did not kill cells cultured in medium containing sucrose. Also, EGCg did not kill oral streptococci adhering to a saliva-coated hydroxyapatite disk. EGCg and epicatechin gallate inhibited lactate dehydrogenase activity much more efficiently than epigallocatechin, epicatechin, catechin or gallocatechin. These results suggest that EGCg is effective in reducing acid production in dental plaque and mutans streptococci.     

Fluoride-supplemented milk inhibits acid tolerance in root caries biofilms

In this study we investigated the effect of fluoride on plaque acid tolerance. The test group consumed 200 ml of milk supplemented with 5 mg F/l as NaF once a day, the milk control group drank 200 ml of unsupplemented milk, and the no-milk control group did not consume milk in this manner. Plaque samples were taken at baseline and after 15 months. The proportion of acid-tolerant bacteria in plaque was estimated using LIVE/DEAD? BacLight? staining after exposure to pH 3.5 for 2 h. The fluoride group showed a statistically significant decrease in plaque acid tolerance compared to baseline. This study shows that daily intake of fluoride in milk reduces plaque acid tolerance.     

Effect of honey in preventing gingivitis and dental caries in patients undergoing orthodontic treatment

ObjectivesThis study was conducted to investigate the following: (1) the effects of chewing honey on plaque formation in orthodontic patients, (2) the effect of chewing honey on dental plaque bacterial counts, (3) determine if honey possesses antibacterial effects on bacteria recovered from plaques.MethodsFemale orthodontic patients (n = 20, 12–18 years of age) participated in this randomized controlled study. The effects of honey were compared to treatment with either 10% sucrose or 10% sorbitol that served as positive and negative controls, respectively. The pH of plaque was measured using a digital pH meter prior to baseline and at 2, 5, 10, 20, and 30 min after chewing honey or rinsing with control solutions and the numbers of Streptococcus mutans, Lactobacilli, and Prophymonas gingivalis in respective plaques were determined. The antibacterial activity of honey was tested against commonly used antibiotics using the disk diffusion method.ResultsSignificant differences in pH were observed in the honey and sucrose groups compared to the pH observed in the sorbitol group (p ? 0.001). The maximum pH drop occurred at 5 min in both the honey and sucrose groups; however the pH in the honey group rapidly recovered 10–20 min after exposure and did not drop below the critical decalcification pH of 5.5. On the other hand, the pH following sucrose exposure fell <5.5 and was associated with a 30 min recovery time. The pH observed for the sorbitol group did not change over time. Bacterial counts were significantly reduced in the honey group compared to the other treatment groups (p ? 0.001) and honey significantly inhibited the growth of all studied strains compared to inhibition observed with antibiotics (p ? 0.001).ConclusionsHoney can be used as an alternative to traditional remedies for the prevention of dental caries and gingivitis following orthodontic treatment.     

Plaque fluid pH, calcium and phosphorus responses to calcium food additives in a chewable candy

Fourteen subjects between 7 and 17 years of age with an equal distribution of low and high caries activity were given: (1) a 10% sucrose rinse, (2) a reference candy, (3) a reference candy with 3% dicalcium phosphate dihydrate, and (4) a reference candy with 0.75% calcium lactate on four different occasions. Plaque samples were collected before and at 15-min intervals after the sucrose rinse or food challenge for a period of 1 h on each occasion. Plaque samples were centrifuged and the extracellular plaque fluid analysed by a microtechnique for pH, total calcium and inorganic phosphorus concentration. There was no significant increase in calcium and phosphorus in plaque fluid for the group using candy with added calcium compared to the reference candy or sucrose rinse. There was no significant difference between the measurements in subjects grouped as caries active or inactive. The results suggest no benefit can be expected from adding dicalcium phosphate dihydrate and calcium lactate to candy to decrease demineralization during a cariogenic challenge.     

Effect of an essential oil mouthrinse, with and without fluoride, on plaque metabolic acid production and pH after a sucrose challenge

This clinical study evaluated the effect of rinsing with an essential oil-containing antiseptic mouthrinse, with or without 100 mg/kg fluoride ion, on the plaque metabolic acid production and plaque pH response after a sucrose challenge. This observer-blind, randomized study used a three-way crossover design. Twenty-four subjects rinsed with 20 ml of one of the following rinses: (1) essential oil (EO) mouthrinse, (2) essential oil mouthrinse plus 100 mg/kg fluoride, or (3) negative control, for 30 s, twice daily for 16 days. On day 17, 1 h after the last mouthrinse, subjects rinsed with 20 ml of mass fraction 10% sucrose solution for 1 min. Seven minutes after the sucrose challenge, supragingival plaque was collected from molar and premolar teeth. Plaque pH and metabolic acid ions were analyzed using a micro pH electrode and capillary electrophoresis, respectively. The results showed that after EO mouthrinse dental plaque produced 36% less lactate, 36% less acetate and 44% less propionate than after the negative control rinse. The dental plaque also exhibited a pH 0.42 unit higher after EO rinse than after the negative control rinse. These results were not affected by the addition of 100 mg/kg fluoride to the EO mouthrinse. From these results we concluded that this EO antiseptic mouthrinse, with or without fluoride ion, is effective in reduction of plaque acidogenicity after a sucrose challenge.     

A role of salivary carbonic anhydrase VI in dental plaque

OBJECTIVE: Carbonic anhydrase (CA) VI is a unique secreted isozyme of CA, which catalyzes the reversible reaction CO2 +H2O<-->H+ +HCO3-. CA VI has been thought to provide a greater buffering capacity to fluids into which it is secreted. This study was performed to confirm this in saliva. DESIGN: Nine healthy subjects participated in the study. The pH of the dental plaque from each subject was monitored after a mouth rinse with 10% sucrose with or without 10(-5)M acetazolamide, a specific inhibitor of CA. Also CA was examined in plaque by enzyme histochemistry, immunohistochemistry and Western blot analysis. RESULTS: Though sucrose and sucrose plus inhibitor yielded Stephan curves with a similar temporal pattern, the pH values of the latter were significantly lower than those of the former. Plaque exhibited CA activity by enzyme histochemistry. Immunohistochemistry and Western analysis demonstrated that the activity was due to CA VI but not to CA I or CA II. CONCLUSIONS: The results indicate that CA VI in saliva penetrates plaque and facilitates acid neutralization by salivary bicarbonate. Therefore, CA VI may be considered an anti-caries protein in saliva.     

An evaluation of the cariogenic potential of baby and infant fruit drinks

The cariogenic potential of a range of fruit drinks was assessed on the basis of plaque pH by the plaque harvesting method. In addition, the inherent pH and titratable acidity of each drink was analysed. The effects of so-called 'no sugar added' and 'sugar-free' drinks were compared with a standard 10% sucrose drink for their effect on plaque pH in vitro, on a group of volunteers, using the Cariogenic Potential Index (CPI). All drinks had a low inherent pH and some a high titratable acidity. All the drinks also depressed the plaque pH below 5.5 within 5 minutes of drinking and had a CPI equal to or greater than a standard 10% sucrose solution.     

The effect of sucrose application frequency and basal nutrient conditions on the calcium and phosphate content of experimental dental plaque

A reduced pool of calcium in dental plaque would be expected to increase the ability of plaque fluid to dissolve the underlying enamel when the pH falls during sugar exposure. We have examined the relationship between frequency of sugar application and Ca and P(i) concentrations in artificial mouth plaque microcosm biofilms. Ten plaques were grown simultaneously from a human saliva inoculum using a continuous flow of simulated saliva, DMM, supplemented with either urea or glucose to modulate the resting pH. In addition the plaques received sucrose applications of varying frequency: 12-, 8-, 6-, or 4-hourly, or not at all. After 15 days the plaques were sampled by taking 4 full-thickness specimens of each, and acid-extractable Ca and P(i), and alkali-soluble protein and carbohydrate were determined. Ca and P(i) concentrations were in a range comparable with those in human plaque, except in the DMM + urea plaque receiving no sucrose, when concentrations were higher. Plaque Ca concentration decreased significantly as sucrose application frequency increased. Increasing sucrose application frequency also reduced the protein, i.e. the cell biomass, content of the plaques and, in the case of DMM + urea plaques, increased the water-insoluble hexose content, presumably extracellular polysaccharide. Reduced biomass was partly due to the bulking of plaque with extracellular polysaccharide, but the marked effect of urea on polysaccharide formation is not understood. This study shows that increasing frequency of sugar application alters dental plaque by reducing its mineral protection capacity.     

2种胶姆糖对菌斑pH值的影响

目的：观察咀嚼2种胶姆糖后口腔菌斑pH值的变化情况.方法：选择8例健康受试者（年龄23～27岁,男4例,女4例）参加3次试验,每次实验开始前停止刷牙24h,在使用10%的蔗糖溶液漱口前以及漱口后5、10、15、20min,用Beetrode pH微电极测量口腔菌斑的pH值,作为基线值.1周后先测量静息pH值,再用蔗糖溶液漱口,1min后给予无糖胶姆糖咀嚼,在5、10、15、20min时间点,分别测量非咀嚼侧的菌斑pH值.1周后重复上述实验,胶姆糖改为含茶多酚胶姆糖.应用SPSS10.0统计软件包对数据进行单因素方差分析和SNK分析.结果：与基线值比较,咀嚼2种胶姆糖都能有效防止由于含漱蔗糖水导致的菌斑pH值下降,并使pH值维持在静息pH值以上.2种胶姆糖之间无显著性差异（P＞0.05）.结论：咀嚼2种胶姆糖均能防止菌斑pH值下降,减少患龋危险.     

Correlations between fluoride concentration,sample weight and acid production in dental plaque from children

Plaque was collected from 60 children aged 7 yr who were participating in a short-term study on the effect of fluoridized milk on plaque F. Plaque F was unaffected by 1 or $\text{5}\text{parts}\text{10}{}^6$ F in milk. Correlations and partial correlations were calculated between: plaque weight, plaque F and the initial and final pH of plaque/sugar incubations. The mean (±SD) plaque weight was 10.1 mg (±4.83) and plaque F (wet weight) was $\text{3.5}\text{parts}\text{10}{}^6$ (±1.79). Plaque F was significantly correlated with final pH (r = +0.42; p < 0.01) but the correlation was of border-line significance (r = +0.23; p = 0.06) when data were standardized on weight. Plaque F and weight were significantly correlated (r = ?0.33; p < 0.05). The correlation between weight and final pH (r = ?0.64; p < 0.01) was little affected by standardizing the data on initial pH or plaque F. The results indicate the importance of considering the weight of plaque when comparing F concentration or pH changes in plaque. The findings do not cast doubt on the validity of earlier results suggesting that pH falls were smaller in plaques from high fluoride areas because there is no evidence that fluoridated water reduced plaque weight.     

微型pH电极直接测试人牙菌斑pH的应用研究

目的：进一步探讨微型ｐＨ电极在原位检测人牙菌斑ｐＨ的可行性，了解漱糖后对菌斑ｐＨ的影响。方法：采用微型蜂式ｐＨ指示电极直接测试人牙邻面菌斑ｐＨ变化。结果：微型ｐＨ电极与玻璃ｐＨ大电极所测结果基本一致；漱糖后菌斑ｐＨ呈下降趋势，２０ｍｉｎ时达到最低点；无龋组与龋敏感组之间的ｐＨ改变无显著性差异。结论：微型ｐＨ电极适用于在原位直接测试菌斑ｐＨ；漱糖后菌斑ｐＨ发生改变，但龋坏与否的个体之间未见明显不同