Effect of chlorhexidine on acidogenicity of dental plaque in vivo

Abstract— In order to evaluate the effect of chlorhexidine on the acidogenicity of dental plaque, pH changes in plaque were measured in situ after sucrose applications. The results showed that a 0.2% chlorhexidine mouthrinse inhibited acid production for a period of 24 h, whereas a 0.05% chlorhexidine rinse showed an inhibitory effect for 4 h. It is suggested that the mechanism involved may be related to the retention of chlorhexidine in the mouth and in plaque providing a bacteriostatic milieu which may be of importance in the observed long-term effect.     

In vivo effect of four antibacterial agents upon the acidogenicity of dental plaque

Abstract – The present study was carried out to compare the effect of chlorhexidine, iodine, alcohol and hydrogen peroxide on the acidogenicity of dental plaque in vivo . Plaque pH changes after application of sucrose were measured before and at various time intervals after the topical application of the agents. The MIC values of the different agents were assessed against plaque bacteria in vitro . The antimicrobial activity of chlorhexidine and iodine were similar whereas alcohol and hydrogen peroxide were less effective in the concentrations employed. The results showed that chlorhexidine 2%, iodine 2%, and alcohol 70% inhibited pH drops for a 24-h period after treatment whereas 3% hydrogen peroxide had no effect. Chlorhexidine 0.2% inhibited acid production to a greater extent than did alcohol 50% and iodine 0.2%. It is suggested that retention of chlorhexidine in plaque may explain the observed prolonged effect.     

Effect of chlorhexidine on acidogenicity of dental plaque in vivo.

In order to evaluate the effect of chlorhexidine on the acidogenicity of dental plaque, pH changes in plaque were measured in situ after sucrose applications. The results showed that a 0.2% chlorhexidine mouthrinse inhibited acid production for a period of 24 h, whereas a 0.05% chlorhexidine rinse showed an inhibitory effect for 4 h. It is suggested that the mechanism involved may be related to the retention of chlorhexidine in the mouth and in plaque providing a bacteriostatic milieu which may be of importance in the observed long-term effect.     

The in vivo effect of glucose solutions containing Cu++ and Zn++ on the acidogenicity of dental plaque

A series of experiments were performed to evaluate the lowest concentration of copper or zinc effective in reducing the acidogenicity of dental plaque in vivo when applied simultaneously with a carbohydrate challenge. The effect of a combination of sub-effective concentrations of these metals was also determined. The results showed a significant reduction in acid production in plaque challenged with glucose solutions containing 0.25 mM CuSO4 or 5.0 mM Zn (C2H3O2).2 as compared to glucose solutions alone. Neither 0.1 mM copper sulphate nor 2.5 mM zinc acetate reduced the acidogenicity of plaque significantly, whereas a combination of these subeffective concentrations was effective. The low metal concentrations causing reduction in acid formation in this study may be explained by the inhibiting substances reaching the bacteria at the same time as the substrate. The synergistic effect of the combination of low concentrations of copper and zinc is consistent with the view that these metals effect dental plaque by the same mechanisms.     

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.     

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 gilutathione, 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 ρ-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 a combination of copper and hexetidine on the acidogenicity and copper accumulation in dental plaque in vivo

A double-blind crossover study on 4 adult volunteers was performed to evaluate the effect of hexetidine on Cu2+ accumulation in dental plaque as well as a possible enhanced effect of copper on inhibition of acid production in the presence of hexetidine. The experimental period was 5 days. No oral hygiene was allowed, and sucrose-containing chewing gum was used to enhance plaque formation during the test period. In order to evaluate the effect on pH, the test persons rinsed with a 15% glucose (w/v) solution on the 5th experimental day. Plaque pH values recorded before and 5 min after the rinse served as control values. One hour later the test persons rinsed with 10 ml of the test solutions for 1 min. Glucose rinses with pH measurements 5 min after the rinse were carried out 0, 3, and 7 h after the test agents were used. The combination of 1.0 mM copper and 2.0 mM hexetidine gave a significant (p less than 0.05) inhibition of acid production at all times compared both to the controls and to each of the test agents separately. Plaque samples were collected with a toothpick immediately before a 1-min rinse with 10 ml of the test solutions. Subsequent plaque samples were taken 5 min and 3 and 8 h after a rinse from corresponding tooth surfaces. Dry weight was estimated, the plaque bacteria digested by HNO3, and the amount of Cu2+ determined by atomic absorption.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

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.     

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 applications 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.     

The effect of different methods of drinking on the pH of dental plaque in vivo

Summary. The effect on the pH of human dental plaque of rinsing and drinking with or without a straw was investigated in eight volunteers using the plaque sampling method. A fruit-based juice was used as the test drink with 10% sucrose and 10% sorbitol solutions serving as positive and negative controls, respectively. The maximum mean plaque pH drop (±SD) when a fruit juice was consumed with a straw (0·82±0·27) was significantly less ( P <0·05) as compared to when it was consumed straight from a cup without a straw (1·14±0·25) and when it was used as a rinse (1·25±0·21). Also, the minimum plaque pH reached after challenge was significantly lower ( P <0·0005) when the subjects rinsed before swallowing (5·22±0·13) as compared with drinking with a straw (5·92±0·39) or without (5·64±0·2). The area under the plaque pH curve was also found to be significantly less when a straw was used (1·81±0·71) as compared with drinking without (2·72±0·93). Drinking with a straw therefore resulted in a less pronounced pH drop and hence might reduce the demineralizing effect on the teeth of various potentially cariogenic drinks.     

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.     

The effect of stannous fluoride on human plaque acidogenicity in situ (Stephan curve).

A system employing an Ingold glass electrode was shown to give reliable measurements of pH drops in dental plaque in situ (Stephan curve readings). The system was used to demonstrate that mouthrinses of 0.2 per cent aqueous solutions of stannous fluoride reduced the pH drops markedly for at least seven hours. A reduction of the stannous fluoride concentration increased the pH drops and decreased the duration of the inhibiting effect. A commercial toothpaste containing stannous fluoride and stannous pyrophosphate had an effect similar to the 0.2 per cent mouthrinse. It was shown that tin accumulated in dental plaque after application of solutions containing stannous fluoride. About 40 per cent of the amount of tin present in the plaque immediately after the mouthrinse was still retained seven hours later. It is suggested that the reduction in acid formation may be caused by stannous ions adsorbing to the bacterial cell wall thus disturbing membrane transport mechanisms, or through inhibition of enzyme systems essential in the fermentation of sugars. The observed effect may be a part of the mechanism involved in the caries preventive function of stannous fluoride.     

Effect of chewing gum on plaque acidogenicity

The aim of this investigation was to study the effect of chewing sucrose-containing gum, xylitol-sorbitol-containing gum and natural gum (Pistacia lenticus) on the pH recovery of sucrose challenged dental plaque. Plaque pH was measured by microtouch electrode method on two-days old plaque. The results of the present study suggest that the chewing gum increases plaque pH. Chewing natural gum created the highest plaque pH values.     

菌斑结构的美蓝和革兰氏染色观察

目的：在建立菌斑口内模型的基础上,了解菌斑形成的超微结构。方法：建立一种口内的菌斑模型,将菌斑标本制成半薄切片,分别用革兰氏和美蓝染色后光镜观察。结果：染色显示菌斑中含有球状菌、杆状菌以及丝状菌等细菌,其中部分细菌会出现坏死现象;革兰氏染色显示阳性菌大多为球状或杆状菌,呈散在分布;阴性菌多为丝状或弯曲状菌,分布呈丛状或簇状。结论：建立的菌斑模型较为接近天然菌斑结构,具有一定的应用价值。     

The effects of beverages on plaque acidogenicity after a sugary challenge

BackgroundCaries prevention traditionally has emphasized the restriction of cariogenic foods and beverages, but it has placed less emphasis on how the choice, combination and sequence of consumed foods and beverages may help reduce plaque acidogenicity. The authors conducted a study to examine whether whole milk, 100 percent apple juice or tap water affect dental plaque acidity in people after a sugary challenge.MethodsTwenty adults participated in a randomized controlled crossover study. Participants consumed four combinations of foods: 20 grams of dry sugary Froot Loops (FL) (Kellogg's, Battle Creek, Mich.) cereal, 20 g of FL followed by 50 milliliters of milk (FL/milk), 20 g of FL followed by 50 mL of juice (FL/juice) and 20 g of FL followed by 50 mL of water (FL/water). The authors used a touch microelectrode to take plaque pH readings at the interproximal space just below the contact area between the maxillary premolars on both left and right sides at two and five minutes after FL consumption and at two to 30 minutes after milk, juice or water consumption.ResultsConsumption of FL plaque pH (standard deviation [SD]) was 5.83 (0.68) at 30 minutes, whereas plaque pH (SD) in the FL/milk group was 6.48 (0.30), which was significantly higher than that for FL/juice (5.83 [0.49]) or FL/water (6.02 [0.41]) (P < .005) at 35 minutes.ConclusionDrinking milk after a sugary cereal challenge significantly reduced plaque pH drop due to the sugary challenge.Practical ImplicationsWhen discussing the cariogenicity of foods and beverages with patients, dentists and other health care professionals should emphasize that the order of ingesting sugary and nonsugary foods is important and may affect their oral health.     

建立口内菌斑模型研究菌斑超微结构

目的:系统了解菌斑形成的超微结构。方法:建立一种口内的菌斑模型,并将1、5、9d形成的菌斑标本制成电镜切片后用透射电镜观察。结果:显示初期菌斑的细菌较少,主要为球状菌。随着时间的延长,细菌的数量和种类开始增加,出现丝状菌和杆状菌。成熟菌斑结构是两侧为丝状菌中间为球状菌的栅栏状结构,其中部分细菌会出现坏死的现象。结论:所建立的菌斑模型较接近天然菌斑结构,具有一定的参考价值。     

Effect of a hydroxyl ion-releasing composite resin on plaque acidogenicity

The aim of this in vivo study was to evaluate the neutralizing capacity, registered as change of plaque acidogenicity, on aged proximal restorations of an ion-releasing composite resin (IRCR), which releases hydroxyl, calcium, and fluoride ions at low pH. Twenty patients, with a mean age of 63 years (range 43-85), participated. All had one aged proximal IRCR restoration (mean age 15 months) and one nonrestored enamel surface to make an intraindividual comparison possible. The neutralizing effect of the IRCR was evaluated by measuring plaque pH, using the microtouch method, after a mouthrinse with 10% sucrose. The plaque pH measurements were repeated 1.5 years later on the IRCR (mean age 34 months), the enamel surfaces and a universal hybrid composite resin (CR). At both 15 and 34 months, the plaque on the IRCR surfaces showed the least acidogenic potential for the whole 60-min time interval. The largest differences between the IRCR, CR and enamel were found during the first 15 min. At 15 months, the total areas under the plaque pH curve (AUC(5.7) and AUC(6.2)) differed significantly between the IRCR and enamel surfaces for the time periods 0-5 min and 5-15 min. At 34 months, significant differences were found between IRCR and CR at the 0- to 5-min time period. It can be concluded that IRCR restorations countered the plaque pH fall and maintained it at levels where less enamel and dentin demineralization can occur.