In vivo measurements of sulcal plaque pH after topical applications of sorbitol and sucrose in rats fed sorbitol or sucrose

To test whether adaptation to sorbitol could be observed in rat plaque, we made pH measurements of rat sulcal plaque in vivo, following topical application of 10% sorbitol solution. Rat pups were inoculated orally with S. mutans 6715 and fed diet MIT 305 (5% sucrose) for 16 days. Baseline sulcal plaque pH response of these rats to topical application of 10% sorbitol solution was measured. One group of 16 rats was then fed 20% sucrose in the diet, and a second group 20% sorbitol. After 13 days' feeding of the experimental diets (four days were used for accommodation to dose, and nine days at the 20% level for sorbitol), there was a significantly greater (p less than 0.01) drop in pH following topical application of 10% sorbitol in this group than in the sucrose-fed group. There was no difference in the pH response of the two groups to topical application of a 10% sucrose solution when tested six days later. The sulcal enamel caries score was significantly higher (p less than 0.001) in the sucrose group, but buccal enamel scores were similar in both groups. Adaptation in rat plaque took place, and could be measured in vivo as an increased drop in sulcal plaque pH following topical application of sorbitol. It is not clear whether this adaptation was primarily due to selection of sorbitol-fermenting micro-organisms, or, more likely, by induction of sorbitol-specific enzymes. Relative to the sucrose-containing diet, the sorbitol diet was hypocariogenic, even under experimental conditions.     

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.     

Adaptation of dental plaque to metabolise maltitol compared with other sweeteners

There is some evidence that plaque can adapt to regular exposure to some bulk sweeteners, leading to increased metabolism and acidogenic potential of the sweetener. This potential for adaptation varies between non-sugar sweeteners and has important implications for manufacturers of food, confectionery and medicines used long-term. Maltitol (99% purity crystalline D-maltitol) is a relatively newly approved non-sugar sweetener and appears to have potentially good dental properties. OBJECTIVES: To compare plaque adaptation to pure sucrose, sorbitol, xylitol or maltitol and the effect of their prolonged use on acid production by plaque from sucrose, in vivo. METHODS: Two series of plaque pH experiments were carried out. Each experiment involved a 14 day adaptive period when four 5 g lozenges of the sweetener were taken between meals each day. Each experiment was separated by a 14 day wash-out period. Acid production was quantified as: (a) minimum pH; and (b) cH area (difference between plaque pH curve and resting value, expressed as cH units). RESULTS: Thirteen adults, of mean age 41 years completed the study. When adaptation of dental plaque to the metabolism of sweeteners was compared, there was a statistically significant difference (p = 0.033) between xylitol and sorbitol, and between xylitol and sucrose but not between xylitol and maltitol. When the effect of prolonged use of sweeteners on acid production after sucrose rinsing was compared, there were no statistically significant differences between the sweeteners. CONCLUSION: Dental plaque does not adapt to metabolise xylitol or maltitol following prolonged exposure over 14 days.     

Mogroside,palatinose, erythritol,and xylitol differentially affect dental plaque pH in caries-active and caries-free children: An in vitro study

ObjectiveTo investigate the effect of mogroside, palatinose, erythritol, and xylitol on the dental plaque pH of children and to compare the plaque pH change between caries-active and caries-free children caused by these sweeteners.MethodsThirty-six children (mean age 6.2 ± 2.9-year-old), caries-active and caries-free, were included. After refraining from practicing oral hygiene, the accessible plaque was collected and equally divided for challenging with 6 different solutions: mogroside, palatinose, erythritol, xylitol, 10% sucrose, and deionized water. The pH of each solution was measured using a digital pH meter at 0, 5, 10, 15, 20, 25, and 30 min.ResultsMogroside, erythritol, xylitol, and water did not significantly lower the dental plaque pH, however, palatinose reduced dental plaque pH comparable to sucrose (p < 0.05). Comparing the caries-active and caries-free groups, only sucrose produced significantly different pH value at min 5 and 10.ConclusionsMogroside, erythritol, and xylitol did not lower the dental plaque pH in caries-active or caries-free children. However, palatinose affected the dental plaque pH similar to sucrose.     

Effect of sorbitol, xylitol, and xylitol/sorbitol chewing gums on dental plaque

The effect of sorbitol (SOR), xylitol (XYL), and the mixture XYL/SOR in chewing gums on dental plaque was studied in three groups of 7 adults (mean age 22.5 years). A fourth group of habitual users of sucrose-containing gums was used as a control. The study involved a 2-week, no-gum period followed by the use of the polyol gums for 2 weeks (10 gums/day in 5 2-gum doses). The daily consumption of XYL and SOR in the XYL and SOR groups was 10.9 g, whereas in the XYL/SOR group, 8.5 and 2.4 g of these polyols were used per day. At the end of the gum period the acidogenic response of the 48-hour plaque was tested using a 10-ml mouthrinse containing the polyols (10% w/v) present in the experimental gums, followed by a 10-ml rinse of 10% (w/v) sucrose solution. The plaque of the subjects who used XYL and XYL/SOR gums showed a significantly better ability to resist pH drops induced by the sucrose rinse than the plaque in the SOR gum group. No changes in resting pH values were observed in the XYL and XYL/SOR groups, whereas the use of SOR gum was associated with significantly lower pH values. The amount of plaque decreased in the XYL/SOR (24.3%) and the XYL (29.4%) groups, but increased in the SOR (48.3%) group, the changes in the SOR group differing significantly from those found in the other groups. The plaque and saliva levels of Streptococcus mutans generally increased in the SOR group, but decreased in groups which used XYL.     

Effects of frequent mouthrinses with palatinose and xylitol on dental plaque

The aim was to evaluate the effects of frequent mouthrinses with palatinose, xylitol and a mixture of palatinose and xylitol on plaque pH, plaque formation and cariogenic microorganisms. 15 subjects refrained from toothbrushing during 3 test periods and rinsed 15 × daily for 4 d with 10 nil of: (1) 50% palatinose, (2) 37.5% palatinose+ 12.5% xylitol, or (3) 50% xylitol. A contrast period with no mouthrinses was also carried out. The 4 periods were carried out in a randomized order with a cross–over design. After the 4–day periods, 3 parameters were measured: (1) plaque pH during the first 30 min after a mouthrinse with palatinose, a mixture of palatinose and xylitol or xylitol alone, directly followed by a 2nd rinse with 10% sucrose; (2) number of mutans streptococci and lactobacilli in plaque and saliva; (3) plaque index. The most pronounced pH drop for the sugar substitutes was found when rinsing with 50% palatinose after the palatinose period, and the least pH drop with 50% xylitol after the xylitol period. The sucrose rinse gave similar pH fall after all 4 periods. The microbial data showed no differences between the 4 periods, but the mutans streptococcus counts in saliva decreased after the xylitol period in contrast to the 3 other periods. Regarding the plaque index, xylitol gave lower scores compared to the other 3 periods.     

The breakdown of glucose, xylitol and other sugar alcohols by human dental plaque bacteria.

The aerobic and anaerobic incubation of plaque bacteria in media consisting of saliva supernatant containing ribitol, arabinitol, sorbitol and mannitol produced a fall in pH whereas incubations and serial transfer in saliva-xylitol media did not lead to any significant change. Addition of 100 mM xylitol did not affect pH fall during incubation with 100 mM sucrose, nor did 5–100 mM xylitol alter the rate of plaque glycolysis in 25 mM glucose solutions when measured as the release of ³H₂O from [5-³H]-glucose at pH 5.0 and 7.5. Plaque carbohydrate catabolism, when measured as the evolution of ¹⁴CO₂ from [U-¹⁴C]-glucose and -xylitol in 25 and 250 mM sugar solutions, respectively, at pH 7.5, showed that carbon dioxide release from xylitol was 7–27 per cent of that released from glucose. However, the anaerobic oxidation of glucose to carbon dioxide only represented 4 per cent of the total glucose utilised by glycolysis in 250 mM glucose solutions and demonstrates the minor role of oxidation in plaque sugar breakdown. Xylitol had no inhibitory effect on plaque sugar metabolism but was itself oxidised, although at a slower rate than was glucose; this metabolic inertness probably contributes to its relative non-cariogenicity.     

Plaque growth while chewing sorbitol and xylitol simultaneously with sucrose flavored gum

In a recent study, sorbitol flavored chewing gum was found neither to increase nor decrease the normal rate of plaque formation, whereas high plaque scores were obtained with sucrose gum during 4 days of no mechanical tooth cleaning. The aim of the present study was to see if chewing sorbitol or xylitol flavored gum together with sucrose gum would affect the growth rate of plaque and whether chewing of xylitol flavored gum could reduce the amount of already formed plaque. Twenty-seven dental students refrained from mechanical oral hygiene measures from Monday to Friday morning for 3 weeks. The students were randomly divided into three groups. A three time crossed-over double-blind approach was used. During each test period one group chewed a combination of one piece sorbitol and one piece sucrose flavored gum five times per day, the second group correspondingly chewed xylitol and sucrose flavored gum, while the third group served as a no hygiene control group. After each test period the students in the control group chewed one piece of xylitol gum every 15 minutes for 2.5 hours. The participants started out each week with clean teeth and were at the end of each test period scored for visible plaque on the facial, mesial and lingual surfaces of their teeth. There was somewhat more plaque after 4 days of chewing sucrose-sorbitol and sucrose-xylitol gum combinations than after no oral hygiene alone. There was no difference between the two test treatments. The 2.5-hour chewing of xylitol flavored gum after the no oral hygiene period did not result in a reduction of the 4-day-old plaque.     

Effect of sorbitol gum chewing on plaque pH response after ingesting snacks containing predominantly sucrose or starch

The purpose of this study was to determine the effect of chewing a sorbitol gum (Trident) for 10 minutes on interproximal plaque pH changes following ingestion of selected sucrose- or starch-containing foods. The snacks containing predominantly sucrose (and/or simple sugars) were chocolate bar, cream-filled cupcakes, cream-filled sandwich cookie, cherry pie and raisins. The snacks containing predominantly starch were oat cereal, granola bars, pretzels, potato chips and corn chips. Plaque pH responses were monitored using an indwelling wire-telemetry system in five adult panelists. The test design involved two sets of 5 x 5 Latin square randomization in which each set consisted of two series of tests. In the first series of tests, the fasted, resting plaque pH was recorded for 5 minutes, panelists ingested the designated snacks for 2 minutes, and the pH response was monitored for the remainder of a 2-hour period. In the second series of tests, the same procedure was followed through the snack ingestion. After the pH response to the snack was monitored for 15 minutes, the panelists were asked to chew one stick of sorbitol gum for 10 minutes and the pH response was then monitored for the balance of the 2-hour period. Results indicated that both the sugar- and starch-containing snacks tested in this study caused significant decreases in interproximal plaque pH. Chewing a sorbitol gum after ingestion of the snacks significantly reduced the demineralizing potential of the plaque. The chewing of sorbitol gum following the ingestion of snacks can be recommended as an adjunct to other caries-preventive oral hygiene measures.     

In vivo acid production from medicines in syrup form

Syrup-form medicines have been shown to cause dental caries in chronically sick children. The acid production of 10 syrupy medicines sweetened with sucrose, fructose, sorbitol, xylitol and saccharin or with a combination of these was tested. The subjects consisted of 7 dental students with low buffering capacity and high levels of Streptococcus mutans. The subjects rinsed with sugar-based liquid medicines for 1 min, after which the plaque pH was measured with a Beetrode touch electrode at approximal sites until 40 min after the rinsing. The minimum pH, the delta pH, and the time under pH 5.7 were measured. From the results it can be concluded that xylitol, xylitol-saccharin and xylitol-sorbitol combinations used as sweeteners in syrup medicines are nonacidogenic, sorbitol is hypoacidogenic, and sucrose and fructose are highly acidogenic.     

pH changes in dental plaque caused by sweetened, iron-containing liquid medicine.

Five commercially available liquid iron medicines and a 5% aqueous sucrose solution were tested in a randomized cross-over study with six subjects at intervals of 3-4 d. The pH in plaque was measured in minute samples taken 5 min before and 5, 10, 20, and 40 min after oral intake of 10-ml volumes of the test solutions. The iron-containing medicines differed with respecto to pH (2.8-7.0), buffer capacity, viscosity, and iron content; two contained sorbitol (28 and 42%) and three sucrose (9, 17, and 47%). As expected, all sucrose-containing preparations produced a significant decrease in pH while no appreciable pH changes followed those with sorbitol. The pH readings after 5 min were affected by the sucrose content rather than the initial pH of the solutions. The decrease in pH was of shorter duration after exposure to the sucrose-containing iron medicines than after the 50% aqueous sucrose solution.     

pH changes in dental plaque caused by sweetened, iron-containing liquid medicine

abstract — Five commercially available liquid iron medicines and a 5% aqueous sucrose solution were tested in a randomized cross-over study with six subjects at intervals of 3–4 d. The pH in plaque was measured in minute samples taken 5 min before and 5, 10, 20, and 40 min after oral intake of 10-ml volumes of the test solutions. The iron-containing medicines differed with respect to pH (2.8–7.0), buffer capacity, viscosity, and iron content; two contained sorbitol (28 and 42%) and three sucrose (9, 17, and 47%). As expected, all sucrose-containing preparations produced a significant decrease in pH, while no appreciable pH changes followed those with sorbitol. The pH readings after 5 min were affected by the sucrose content rather than the initial pH of the solutions. The decrease in pH was of shorter duration after exposure to the sucrose-containing iron medicines than after the 50% aqueous sucrose solution.     

Turku sugar studies XXI: Xylitol-, sorbitol-, fructose- and sucrose-induced physico-chemical changes in saliva

The aim was to study eventual physico-chemical changes occurring in whole saliva due to sweetened and unsweetened stimulators. The assay was carried out in 10 female subjects with regard to changes of pH, buffering capacity and electrolytes in saliva as influenced by chewing of fructose, sucrose, sorbitol and xylitol gum, gum base and paraffin. The flow rate of saliva was measured in relation to use of xylitol and sucrose chewing gum and unsweetened gum base. These sweeteners increased significantly the salivary flow rate in comparison to the unsweetened gum base. Generally, xylitol and sorbitol on one hand, and sucrose and fructose on the other, behaved in an almost similar way. Increased buffering capacity and elevation of pH in saliva was found in the presence of the polyols tested.     

Turku sugar studies XXI. Xylitol, sorbitol-, fructose- and sucrose-induced physico-chemical changes in saliva.

The aim was to study eventual physico-chemical changes occurring in whole saliva due to sweetened and unsweetened stimulators. The assay was carried out in 10 female subjects with regard to changes of pH, buffering capacity and electrolytes in saliva as influenced by chewing of fructose, sucrose, sorbitol and xylitol gum, gum base and paraffin. The flow rate of saliva was measured in relation to use of xylitol and sucrose chewing gum and unsweetened gum base. These sweeteners increased significantly the salivary flow rate in comparison to the unsweetened gum base. Generally, xylitol and sorbitol on one hand, and sucrose and fructose on the other, behaved in an almost similar way. Increased buffering capacity and elevation of pH saliva was found in the presence of the polyols tested.     

Human dental plaque pH, and the organic acid and free amino acid profiles in plaque fluid, after sucrose rinsing

The relationship between these factors was studied in plaque and plaque fluid samples taken at intervals during the Stephan pH curve following a sucrose mouth rinse. Levels of lactate rose after the rinse, then fell during the pH recovery phase. Levels of acetate, propionate and phosphate fell after rinsing, then rose again. Amino acid concentrations also changed, with many showing a fall followed by a rise; others rising then falling; and some showing a more variable or complex pattern. In resting plaque fluid, only alanine, proline, glutamic acid, glycine and ammonia were present at concentrations above 1 mmol/l. Delta-aminovaleric acid was detected at levels below those that have been found in monkeys. Hydroxyproline and hydroxylysine were consistently detected, levels of arginine were generally low, and those of cystine consistently very low. The results may provide a basis for understanding the complex metabolic interrelations that occur in the course of the Stephan curve and which may reflect or produce the observed pH changes. They suggest that besides the amount of acid produced, the type of acid, buffering power and base production should be considered as determinants of plaque pH.     

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.     

Comparative effects of the substance-sweeteners glucose, sorbitol, sucrose, xylitol and trichlorosucrose on lowering of pH by two oral Streptococcus mutans strains in vitro

Streptococcus mutans suspensions were incubated with each of the sweeteners in suspending media of increasing complexity. The lower pH levels were generally attained by sucrose and glucose; higher pH values were obtained with sorbitol, trichlorosucrose, and xylitol, respectively. The acidogenicity of sucrose was more often decreased by the presence of trichlorosucrose than by the presence of xylitol.     

咀嚼无糖口香糖对含漱蔗糖溶液后牙菌斑原位pH值的影响

目的 通过对牙菌斑原位pH值变化的动态监测，观察咀嚼无糖口香糖对牙菌斑原位pH值的影响。方法 采用受试者自身对照的临床试验方法，选择16名健康成人志愿者为受试者，年龄23～32岁，其中男性6名，女性10名。首先测定受试者48h菌斑的静止pH值，以及受试者用10％蔗糖溶液含漱1min后在5、10、20和30min时菌斑的pH值，取得受试者的Stephan曲线作为基线对照；而后观察咀嚼两种益达无糖口香糖对含漱10％蔗糖溶液后菌斑pH值变化的影响。菌斑原位pH值的测定采用pH微电极接触法在口内直接测量。结果 含漱10％蔗糖溶液后立即开始咀嚼无糖口香糖可使菌斑pH值在各检测时间点(含漱10％蔗糖溶液后5、10、20和30min)均维持在静止pH水平，无明显下降；含漱10％蔗糖溶液后在5min时开始咀嚼无糖口香糖则使菌斑pH值从含漱蔗糖溶液后5min时的5．59迅速回升至10min时的6．98。结论 受到蔗糖攻击后，咀嚼无糖口香糖可迅速缓冲菌斑的酸性产物，升高菌斑pH值。     

Fermentation of sugars and sugar alcohols by plaque Lactobacillus strains

Objective

The objective was to analyse the ability of Lactobacillus strains isolated from supragingival plaque of subjects with hyposalivation and from healthy controls to ferment sugars and sugar alcohols.

Material and methods

Fifty strains isolated from interproximal plaque from subjects with radiation-induced hyposalivation (25 strains), subjects with primary Sjögren’s syndrome (16 strains) and from subjects with normal salivary secretion rate (9 strains) were tested. Growth and pH were determined after 24 and 48 h of anaerobic incubation in vials containing basal media with 1 % of glucose, fructose, sucrose, mannitol, sorbitol or xylitol.

Results

No differences between strains isolated from hyposalivated subjects and controls were detected. All strains lowered the pH to <5.0 from fructose and the majority of the strains from glucose and sucrose. A pH of <5.5 was seen for 52 % of the strains using mannitol, 50 % using sorbitol and 36 % using xylitol. The ability to produce acids from sugars and sugar alcohols was highest among strains of Lactobacillus rhamnosus, Lactobacillus casei and Lactobacillus paracasei and lowest among Lactobacillus fermentum strains.

Conclusion

A large number of Lactobacillus strains are able to ferment not only sugars but also the sugar substitutes mannitol, sorbitol and xylitol to pH levels critical for enamel demineralisation.

Clinical relevance

Our findings suggest that products containing mannitol, sorbitol and/or xylitol may contribute to the acidogenic potential of the dental plaque and especially in hyposalivated subjects with high numbers of lactobacilli.     

The effects of different concentrations of sucrose, fructose, and glucose on pH changes by Streptococcus mitior in an artificial mouth

The aim of this study was to determine the effects of the initial sucrose (S) concentration, as well as those of fructose (F), glucose (G), and invert sugar (F/G), on the pH developed by a layer of S. mitior, to represent dental plaque, in an artificial mouth which simulates the process of oral sugar clearance. At S, F. G, and F/G concentrations of 2% and with normal oral sugar clearance rates, the bacteria produced a smaller pH fall from S than from the other sugars; at initial concentrations of 20%, however, the differences were not significant. With constant S concentrations of 0.5-35%, the minimum pH reached was 4.03 +/- 0.14 (S.D.); with S concentrations of 50% and above, slightly but significantly higher values (4.41 +/- 0.34) occurred. However, with normal sugar clearance, the pH fall was much less than with a constant concentration and was dependent on the S concentration over the range of 0-10%, but was independent at higher concentrations. Exposure of the bacteria to S for as short a period as two min during normal sugar clearance gave a nearly maximum pH fall. This suggests that rinsing the mouth with water more than two min after consumption of sucrose in liquid form will have very little effect in reducing the pH fall in dental plaque. A more appropriate method for reducing acid formation by dental plaque would be consumption of a salivary stimulant which would increase the flow rate and buffer capacity of the saliva.