Effect of a lactose-containing sweetener on root dentine demineralization in situ

Enhancing Intraoral Fluoride Retention in Older Adults: A Randomized Crossover Study

INTRODUCTION

Previous studies have shown that a calcium prerinse can increase intraoral fluoride retention from a fluoride rinse. To explore the potential of this approach to control root caries, we assessed intraoral fluoride bioavailability after a calcium prerinse in older adults with normal to low salivary flow rates.

METHODS

In a 2-period crossover trial (NCT04239872), 20 participants (65-80 y old), with low or normal salivary flow rate, rinsed for 1 min with a 0.05% NaF mouth rinse (226 ppm F, F only) or with this rinse immediately after a 1-min rinse with 150 mM calcium lactate (Ca→F). Dental biofilm and saliva samples were collected before and up to 2 h after the rinse(s). Fluoride concentrations in saliva (whole and clarified) and dental biofilm (fluid and solid phases) were blindly determined. Data were statistically analyzed by a mixed-effects model for the effect of treatment, time, and their interaction (α = 5%).

RESULTS

The Ca→F group resulted in significantly higher fluoride concentrations in all variables analyzed, for almost all of the collection time points. The effect was greater in the biofilm solids and whole saliva (compatible with the formation of calcium fluoride deposits) and still significant (P < 0.001) after 2 h in the biofilm fluid and clarified saliva, suggesting that fluoride stored in insoluble particles was released, increasing free fluoride.

CONCLUSION

The use of a calcium prerinse before a fluoride rinse was able to prolong intraoral fluoride bioavailability in older adults.

KNOWLEDGE TRANSFER STATEMENT

A calcium prerinse increased intraoral fluoride bioavailability in older individuals. This approach could be used to improve root caries control without the need to increase the fluoride concentration in dental products.

In Silico Modeling of Hyposalivation and Biofilm Dysbiosis in Root Caries

Root caries progression is aggravated by hyposalivation, which can accelerate the conversion of a dental biofilm from having a symbiotic microbial relationship with the host (predominance of nonaciduric species) to a dysbiotic one (dominated by aciduric species). Using a mathematical model previously employed to investigate factors associated with biofilm dysbiosis, we systematically explored the deleterious effect of hyposalivation on the composition of the biofilm and the risk of root dentin demineralization. By varying the clearance half-times of sugar (i.e., readily fermented dietary carbohydrates), we simulated hyposalivation and investigated its effect on 1) the time that the biofilm pH spends below the minimum for dentin or enamel demineralization and 2) the conversion of the biofilm from a symbiotic to dysbiotic composition. The effect of increasing sugar clearance half-times on the time that the biofilm pH is below the threshold for demineralization was more pronounced for dentin than for enamel (e.g., increasing the clearance half-time from 2 to 6 min doubled the time that the biofilm pH was below the threshold for dentin demineralization). The effect on biofilm composition assessed at 50 d showed that the conversion from a symbiotic to a dysbiotic biofilm happened around a frequency of 6 sugar intakes per day when the clearance half-time was 2 min but only 3 sugar intakes per day when the clearance half-time was 6 min. Taken together, the results confirm the profound effect that prolonged sugar clearance has on the dynamics of dental biofilm composition and the subsequent risk of root caries. This in silico model should be applied to study how interventions that alter salivary clearance rates or modify biofilm pH can affect clinical conditions such as root caries.

Saccharide Characteristics and Their Potential Health Effects in Perspective

To understand the effects of saccharides on our metabolism and health, we need a clear understanding of what they are, how they differ, and why some types are deemed "less healthy" and others "better for health." There are various ways to look at this topic. Firstly, saccharides can be classified according to their degree of polymerization (DP). This classification is useful when qualitative or quantitative analysis and calculation of intakes are required or for food-labeling definitions. However, it does not account for the fact that saccharides with a similar DP can differ in molecular composition, which will influence digestion, absorption, and metabolism. Secondly, another approach widely used in the biomedical and nutritional sciences is therefore a physiological classification, which addresses the rate and degree of digestibility and absorption, the glycemic response, and the metabolic fate. The individual health status also plays a role in this respect. An active, lean person will have a metabolic response that differs from an inactive person with overweight and insulin resistance. However, this approach will not give a complete answer either because the characteristics of the matrix/meal in which these carbohydrates (CHOs) are present will also influence the responses of our body. Thirdly, one can also rank CHOs by comparing their functional/technological properties, such as relative sweetness, viscosity, and solubility. Understanding CHO characteristics and related physiological responses will help understand health and disease implications. Therefore, a brief outline of different carbohydrate classifications is presented. This outline will be placed in the context of potential overall effects after consumption. The answer to the question whether we should we eat less of certain sugars depends on the angle from which you look at this matter; for example, do you address this question from a single molecular characteristic point of view or from a meal quality perspective? Looking at one particular CHO characteristic will almost always lead to a different conclusion (e.g., the labeling of fructose as toxic) than evaluating from a "total perspective" (fructose has adverse effects in certain conditions). Examples are given to help understand this matter for the benefit of justified dietary/food-based recommendations.

Cariogenic Potential of Sucrose Associated with Maltodextrin on Dental Enamel

Maltodextrin is a hydrolysate of cornstarch and has been widely used in the food industry associated with sucrose. The addition of starch can increase the cariogenic potential of sucrose; however, there are sparse data regarding the cariogenicity of sucrose associated with maltodextrin. Therefore, the aim of this study was to test in situ if maltodextrin could increase the cariogenic potential of sucrose. This was an in situ, randomized, crossover, split-mouth, and double-blind study. Volunteers wore palatal appliances containing bovine enamel blocks for 2 periods of 14 days. They dripped the following solutions on the enamel blocks 8 times per day: deionized distilled water (DDW), maltodextrin (M), sucrose + maltodextrin (S+M), or sucrose (S). At the end of each experimental period, biofilms were collected and analyzed for microbiological (mutans streptococci, lactobacilli, and total microorganisms counts) and biochemical (calcium, inorganic phosphate, fluoride, and insoluble extracellular polysaccharides concentrations) compositions. The enamel demineralization was assessed by microhardness. Treatments S and S+M resulted in a lower inorganic composition and higher concentration of insoluble extracellular polysaccharides in the biofilms, and higher enamel mineral loss compared to DDW and M. It can be concluded that the cariogenic potential of sucrose is not changed when this carbohydrate is associated with maltodextrin (dextrose equivalent 13-17).

Validation of a Cariogenic Biofilm Model to Evaluate the Effect of Fluoride on Enamel and Root Dentine Demineralization

Due to gingival recession both enamel and root dentine are at risk of developing caries. Both tissues are exposed to a similar environment, however there is not a validated model to evaluate the effect of fluoride on these dental substrates simultaneously. Hence, this study aimed to validate a caries model to evaluate the effect of fluoride to prevent demineralization on enamel and root-dentine. Streptococcus mutans UA159 biofilms were formed on saliva-coated bovine enamel and root dentine slabs (n = 12 per group) mounted in the same well of culture plates. The biofilms were exposed 8×/day to 10% sucrose and treated 2×/day with fluoridated solutions containing 0, 150, 450, or 1,350 ppm F; thus, simulating the use of low to high fluoride concentration toothpastes. The pH values of the culture medium was monitored 2×/day as a biofilm acidogenicity indicator. After 96 h, biofilms were collected for fluoride concentration analysis. The percentage of surface hardness loss (%SHL) was calculated for slabs. The fluoride uptake by the enamel and dentine was also determined. The model showed a dose-response because the biofilm and fluoride uptake increased and %SHL decreased at increasing fluoride concentrations (p < 0.05). Fluoride in the biofilm formed on dentine and fluoride uptake by dentine were higher than those for enamel. With the same fluoride concentration treatment, the percentage of reduction of demineralization was lower for dentine than for enamel. In conclusion, the model was validated in terms of a dose-response effect of fluoride on enamel and root dentine. Furthermore, the findings support the clinical data, suggesting that higher fluoride concentrations are necessary to control caries of root dentine than of enamel.

A systematic methodology to estimate added sugar content of foods

BACKGROUND/OBJECTIVES

The effect of added sugar on health is a topical area of research. However, there is currently no analytical or other method to easily distinguish between added sugars and naturally occurring sugars in foods. This study aimed to develop a systematic methodology to estimate added sugar values on the basis of analytical data and ingredients of foods.

SUBJECTS/METHODS

A 10-step, stepwise protocol was developed, starting with objective measures (six steps) and followed by more subjective estimation (four steps) if insufficient objective data are available. The method developed was applied to an Australian food composition database (AUSNUT2007) as an example.

RESULTS

Out of the 3874 foods available in AUSNUT2007, 2977 foods (77%) were assigned an estimated value on the basis of objective measures (steps 1-6), and 897 (23%) were assigned a subjectively estimated value (steps 7-10). Repeatability analysis showed good repeatability for estimated values in this method.

CONCLUSIONS

We propose that this method can be considered as a standardised approach for the estimation of added sugar content of foods to improve cross-study comparison.

Effects of lactose-containing stevioside sweeteners on dental biofilm acidogenicity

The aim of this study was to evaluate the effect of a commercial lactose-containing stevioside sweetener on biofilm acidogenicity in vivo. Nine volunteers refrained from brushing their teeth for 3 days in five phases. On the 4th day of each phase, the pH of the biofilm was measured by the "Strip method". Interproximal plaque pH was measured before and up to 60 minutes after a 10 mL mouthrinse for 1 minute with the test solutions: I - sweetener with 93% lactose and 7% stevioside; II - sweetener with 6.8% saccharin, 13.6% cyclamate, and 0.82% stevioside; III - 18% sucrose solution (positive control); IV - mineral water (negative control); and V- 93% lactose solution. The results revealed that the most pronounced pH fall was found with sucrose (positive control), followed by the 93% lactose solution, the sweetener with lactose + stevioside, the sweetener with saccharin + cyclamate + stevioside, and finally water (negative control). According to the area under the curve, the two sweeteners containing stevioside were significantly different, and the sweetener with lactose + stevioside was significantly different from water but not from sucrose. The critical pH for dentin demineralization (pH ≤ 6.5) was reached by all volunteers after rinsing with sucrose solution, lactose solution, and the stevioside + lactose sweetener. Analysis of the data suggests that lactose-containing stevioside sweeteners may be cariogenic, especially to dentin.

Evaluation of cariogenic potential of dry powder inhalers: A case-control study

Objective:

Dry powder inhalers (DPIs) are commonly employed in the management of asthma and other diseases with airway obstruction. A causal relationship of DPI use and occurrence of dental caries has been speculated. The present case-control study was therefore designed to examine the potential link between dental caries and specific use of dry powder inhalers in patients with bronchial asthma.

Materials and Methods:

The present study was conducted on 100 asthmatic patients aged between 10 and 45 years who were using DPIs for at least one year. The control group (n = 100) was selected from non-asthmatic individuals and were matched with the study group with respect to age, gender, and socio-economic status.

Results:

The results revealed that asthmatic subjects exhibited higher occurrence of dental caries in comparison to control group, but the difference was statistically non-significant. The mean decayed, missing, and filled teeth (DMFT) indices scores in asthmatic and control group were found to be 1.71 ± 2.34 SD and 1.46 ± 1.89 SD (P = 0.408), respectively. Likewise, the mean decayed, missing, and filled surfaces (DMFS) indices scores in both the groups were 2.41 ± 3.84 SD and 2.34 ± 4.48 SD (P = 0.90). However, increased frequency of DPI use was associated with significant risk of caries (P = 0.01). It has been observed that oral rinsing after an inhaler use limited the occurrence of dental caries to a certain extent although was non significant.

Conclusions:

Dry powder inhaler use in patients with bronchial asthma was not associated with significant risk of dental caries.

Influence of fluoride-releasing restorative material on root dentine secondary caries in situ

The usefulness of fluoride-releasing restorations in secondary caries prevention may be questioned because of the presence of other common sources of fluoride and because of ageing of the restorations. This study tested the hypothesis that glass-ionomer cement restorations, either aged or unaged, do not prevent secondary root caries, when fluoride dentifrice is frequently used. Sixteen volunteers wore palatal appliances in two phases of 14 days, according to a 2 x 2 crossover design. In each phase the appliance was loaded with bovine root dentine slabs restored with either glass-ionomer or resin composite, either aged or unaged. Specimens were exposed to cariogenic challenge 4 times/day and to fluoridated dentifrice 3 times/day. The fluoride content in the biofilm (FB) formed on slabs and the mineral loss (DeltaZ) around the restorations were analysed. No differences were found between restorative materials regarding the FB and the DeltaZ, for either aged (p = 0.792 and p = 0.645, respectively) or unaged (p = 1.00 and p = 0.278, respectively) groups. Under the cariogenic and fluoride dentifrice exposure conditions of this study, the glass-ionomer restoration, either aged or unaged, did not provide additional protection against secondary root caries.

Experts’ Opinions on the Role of Diet in Caries Prevention

A questionnaire was sent to 54 experts in preventive dentistry in 23 European countries in order to make an inventory of existing national dietary guidelines for the prevention of dental caries. In addition, the experts were asked to give their personal opinion on several issues concerning the relationship between diet and dental caries. Forty-five experts from 20 countries returned the questionnaire. In 13 European countries dietary guidelines for caries prevention were available issued by a National (Dental) Association or a Government Body. All guidelines emphasised a reduction of the frequency of intakes of cariogenic foods. Two of them included a threshold level for the amount of sugar. When asked for their personal opinions, almost all experts mentioned reduction of frequency of 'cariogenic' intakes as the principal dietary messages for caries prevention. Four experts, however, explicitly mentioned that proper oral hygiene with fluoride toothpaste is more important. There was no agreement among the experts about a daily number of cariogenic intakes in between meals that can be regarded as safe, nor whether the message: 'Use products with sugar substitutes' should be part of the dietary guidelines for the prevention of dental caries. There was no agreement amongst experts on preventive dentistry in Europe on the contemporary validity of the paradigm: 'Sucrose is the arch criminal of dental caries.' Taking the variation in opinions into account and the fact that a balanced diet may lead to a moderate eating and snacking frequency, the authors propose that the emphasis on good versus bad foods for caries prevention should be replaced by an emphasis on good versus bad diets.

Caries progression and inhibition in human and bovine root dentine in situ

Since the use of bovine instead of human dentine to evaluate cariogenic and anticariogenic substances is not well established, this in situ study was conducted. Eleven volunteers wore palatal acrylic devices containing 4 dentine slabs (2 human and 2 bovine). Sucrose solution (20%) was dripped over all slabs 4 times a day, simulating a cariogenic challenge. Dentifrice slurries, fluoridated or not, were dripped over specified dentine slabs 3 times a day to evaluate caries reduction. After 14 days, the biofilm formed on the dentine slabs was collected for microbiological analysis. In dentine, mineral loss (DeltaZ) and lesion depth (LD) were determined by cross-sectional microhardness and by polarized light microscopy, respectively. The total streptococci and mutans streptococci counts in the biofilm formed either on human or on bovine slabs, whether treated or not with fluoride dentifrice, were not statistically different. The DeltaZ and the LD values of dentine treated with fluoride dentifrice were significantly lower than the values of dentine treated with non-fluoride dentifrice. The differences in the DeltaZ and LD values between the human and bovine dentine were not statistically significant. The results suggest that bovine dentine can be used instead of human to evaluate caries development and inhibition.

A modified pH-cycling model to evaluate fluoride effect on enamel demineralization

Since in vitro pH-cycling models are widely used to study dental caries, they should allow evaluations of fluoride effect on early stages of caries development. Therefore, acid etching on enamel surface must be avoided, enabling surface microhardness (SMH) analysis. In the present study, the pH-cycling model originally described by Featherstone et al.9 (1986) was modified to preserve the enamel surface and to produce early carious lesions that could be evaluated using SMH and cross-sectional microhardness (CSMH) measurements. In order to validate this modified model, a dose-response evaluation with fluoride was made. Human enamel blocks with known SMH were submitted to such regimen with the following treatments: distilled deionized water (DDW; control) and solutions containing 70, 140 and 280 ppm F. Data from %SMH change and deltaZ (mineral loss) showed a statistically significant negative correlation between F concentration in treatment solutions and mineral loss. In conclusion, the modified pH-cycling model allowed the evaluation of changes on the outermost enamel layer during caries development, and a dose-response effect of fluoride reducing enamel demineralization was observed.