Effect of Frequency of Sucrose Exposure on Dental Biofilm Composition and Enamel Demineralization in the Presence of Fluoride

Nutritional factors associated with early childhood caries: A systematic review and meta-analysis

Background

Many studies have examined the relationship between nutrition and dental caries. However further studies are needed regarding nutritional factors that can have a strong impact on the incidence of early childhood caries (ECC). Nutrition is one factor that determines caries occurrence. Exposure to carbohydrates in the oral cavity causes carbohydrate fermentation, which produces acids. This acidic substance erodes the enamel surface of teeth, leading to ECC. This systematic review and meta-analysis of cohort studies assessed the aspects of nutrition and diet that contribute to the incidence of ECC in children.

Materials and methods

We conducted a systematic review by extracting data according to Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. A search was conducted of published articles in Scopus, MEDLINE via PubMed, and Science Direct using the keywords "nutrition," "sugar," "carbohydrate," "dietary habit," "dental caries," and "oral health." The protocol was registered at PROSPERO 2023 (Registration ID: CRD42023394583).

Results

The article screening yielded 6 articles that met the inclusion criteria. From the total of 443 studies found. Those that could not determine a correlation between the ECC variables and nutrition and with data analyses that only used a bivariate analysis were excluded. The results of the meta-analysis showed that nutritional factors had the strongest impact on caries including feeding practice (OR 3.64; 95% CI 2.03, 6.55), sugar intake (OR 3.24; 95% CI 2.59, 4.03), and low fruit and vegetable intake (OR 2.71; 95% CI 1.47, 5.01).

Conclusion

Two nutritional factors had the strongest relationship with the risk of ECC: feeding practice and sugar intake. The lowest risk factor for causing ECC was low fruit and vegetable intake.

Influence of Sucrose and Arenga pinnata Solutions on Enamel Surface Demineralization: A Profilometric Study

Background Dental caries is a multifactorial disease that has the potential to impact individuals across various life stages. The influential role of sugar as a contributing risk element in the inception and advancement of dental caries is significantly pronounced.  Aim The research aim was to analyze and compare the enamel surface roughness in teeth exposed to sucrose and Arenga pinnata (palm sugar) solutions by using a stylus profilometer Materials and methods In this investigation, 34 freshly extracted anterior teeth were obtained and they were split into two groups depending on the solution in which they were immersed. Group A consists of 17 teeth immersed in 1% sucrose solution supplemented in brain heart infusion (BHI) broth solution and Group B consists of 17 teeth immersed in 1% Arenga pinnata BHI broth. Each sample served as its own control. Streptococcus mutans was inoculated into these groups and they were immersed in their respective solution for five days. A stylus profilometer was utilized to measure the surface roughness of the teeth in this study. Data analysis involved paired t-tests for intragroup comparisons and independent t-tests for intergroup comparisons using SPSS software version 23. Results After five days of exposure to palm sugar or sucrose, it was observed that there was demineralization of the enamel surface on both samples. Although there was no statistical significance (p<0.05) when an independent t-test was conducted among these samples, there was a visible increase in the numerical values of Ra, Rq, Rz of teeth exposed to sucrose compared to palm sugar with a p-value of 0.529, 0.122 and 0.357, respectively. Conclusion From this study, it was concluded that although both sucrose and Arenga pinnata cause demineralization of enamel, it was shown that the latter caused lesser demineralization when compared to refined sugars to a certain extent. This study establishes a foundation for forthcoming investigations that could potentially explore the utilization of natural sugars as a substitute for sucrose, while also evaluating the mechanistic aspects underlying the impact of these sugars on enamel demineralization.

The Current Antimicrobial and Antibiofilm Activities of Synthetic/Herbal/Biomaterials in Dental Application

Herbal and chemical products are used for oral care and biofilm treatment and also have been reported to be controversial in the massive trials conducted in this regard. The present review is aimed at evaluating the potential of relevant herbal and chemical products and comparing their outcomes to conventional oral care products and summarizing the current state of evidence of the antibiofilm properties of different products by evaluating studies from the past eleven years. Chlorhexidine gluconate (CHX), essential oils (EOs), and acetylpyridinium chloride were, respectively, the most commonly studied agents in the included studies. As confirmed by all systematic reviews, CHX and EO significantly control the plaque formation and gingival indices. Fluoride is another interesting reagent in oral care products that has shown promising results of oral health improvement, but the evidence quality needs to be refined. The synergy between natural plants and chemical products should be targeted in the future to accede to the formation of new, efficient, and healthy anticaries strategies. Moreover, to discover their biofilm-interfering or biofilm-inhibiting activities, effective clinical trials are needed. In this review article, therapeutic applications of herbal/chemical materials in oral biofilm infections are discussed in recent years (2010-2022).

Nonrestorative treatment of initial caries lesion in primary teeth: a systematic review and network meta-analysis

OBJECTIVE

To identify the best available approach to avoid initial caries lesions progression in primary teeth.

MATERIALS AND METHODS

Search was performed in MEDLINE/Pubmed, Web of Science, Embase and CENTRAL databases until March 2021. Studies compared treatment options to avoid the initial caries lesion progression with at least 12 months of follow-up were included. Network meta-analyses were conducted considering the non-progression of caries lesions as an outcome.

RESULTS

Potentially eligible studies were screened (n = 2820) and eleven were included. Six studies evaluated the use of fluoride varnish, resin infiltration, sealing, and toothbrushing/flossing on proximal initial caries lesions. When considering occlusal surfaces, only two studies evaluating the ozone gas, fluoride varnish, resin infiltration, and sealants were included. For buccal/lingual surfaces, three studies evaluating toothbrushing, CPP-ACP paste, fluoride varnish, and resin infiltration were included. For all types of surfaces, the resin infiltration showed the best probability to avoid the progression of initial caries lesions.

CONCLUSION

The limited number of included studies, most with a high risk of bias and lack of hard outcomes, such as frank cavitation, makes it not feasible to recommend a specific management approach for initial caries lesion control in primary teeth with a high certainty of evidence. PROSPERO: #CRD42016037781.

Effect of sweetener containing Stevia on the development of dental caries in enamel and dentin under a microcosm biofilm model

OBJECTIVE

This study compared the effect of commercial and pure sweetener containing stevia to that of aspartame, to sucrose and xylitol on the development of dental caries.

METHODS

228 bovine enamel and root dentin were exposed to microcosm biofilm model using human saliva. From the 2^nd to the 5^th day, the samples were exposed daily to McBain saliva supplemented with 0.2% of the respective sweeteners/sugar, under 5% CO₂ and 37 °C. The lactic acid and the colony-forming units (CFU) were quantified. The demineralization was analyzed by TMR. The data were compared statistically (Kruskal-Wallis/ Dunn, p<0.05).

RESULTS

Pure stevia, pure aspartame, xylitol and control were able to significantly reduce 92% of lactate production compared to sucrose. Stevia finn, aspartame finn and sucrose showed similar production of lactic acid (around 0.45±0.12 g/L and 0.67±0.18 g/L, for enamel and dentin, p<0.0001). With respect to total lactobacilli and S. mutans/S. sobrinus CFU, xylitol and control did not show growth on enamel, while CFU numbers were found in stevia finn, aspartame finn and sucrose groups for both tissues. Enamel and dentin demineralization was significantly reduced for xylitol, control, pure stevia and pure aspartame (85% and 83% reduction, respectively) compared to stevia finn, aspartame finn and sucrose, which in turn did not differ from each other (sucrose ΔZ: 2913.7 ± 646.7 vol%.µm for enamel and 3543.3 ± 432.5 vol%.µm for dentin).

CONCLUSIONS

Commercial sweeteners containing stevia and aspartame proved to be as cariogenic as sucrose, which may be due to the other components, since the pure forms were not cariogenic.

CLINICAL RELEVANCE

Our study showed that some commercial sweeteners (aspartame and stevia) are as cariogenic as sucrose, which may be due to the presence of lactose. The population should be advice about the presence of lactose in such brand names, to avoid their consume.

Effect of Er:YAG Laser Irradiation and Acidulated Phosphate Fluoride Therapy on Re-Mineralization of White Spot Lesions

Statement of the Problem:

Studies on the efficacy of erbium laser for enhancement of enamel resistance to acid attacks and its effects on fluoride uptake by the enamel are limited.

Purpose:

This study sought to assess and compare the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation and application of acidulated phosphate fluoride (APF) gel (alone and in combination) on remineralization of artificial white spot lesions (WSLs).

Materials and Method:

This in vitro, experimental study evaluated 90 buccal and lingual slabs of extracted human premolars. The specimens underwent pH cycling to induce WSLs. They were then randomly divided into 6 groups of caries-free positive control (c+), negative control with WSLs (ws), 1.23% APF gel applied on the enamel (F), Er:YAG laser irradiation (80 mJ, 10 Hz, and 8 J/cm²) of enamel (L), APF gel application followed by laser irradiation (FL), and laser irradiation followed by fluoride gel application (LF). The fluoride ion content of specimens was measured before and after the intervention using a potentiometer. Data were analyzed by ANOVA (p< 0.05).

Results:

APF gel application before/after laser irradiation maximally increased the fluoride uptake by the enamel (p= 0.000). Application of APF gel in group F and laser irradiation in group L increased fluoride uptake by the enamel, compared with groups 1 and 2 (p= 0.000). Laser- treated (L) and APF-treated (F) groups had no significant difference in this respect (p= 0.945). Maximum fluoride concentration was noted in combined laser and fluoride groups (FL=332.07ppm and LF=341.27ppm) with no significant difference between the two (p= 1.000).

Conclusion:

Er:YAG laser irradiation changes the chemical composition of enamel and probably promote its remineralization, especially when combined with APF gel application, which highlights its cariostatic potential.

Modelling the impact of increase in sugar prices on dental caries in India

OBJECTIVES

This study aims to assess the impact of raising the price of sugar and/or sugar-sweetened beverages (SSBs) on caries incidence in the Indian population.

METHODS

A tooth-level decision-analytic model was developed to evaluate a change in caries increment after increasing the price of Sugar and SSBs. The transition of a tooth from a caries-free state to the state of tooth loss in both scenarios was modelled with the help of a Markov model for a time horizon of 63 years, ranging from 2021 to 2083 for the 12-year-old population cohort of India. A conceptual framework was designed to implicate the possible effects of an increase in sugar prices on the reduction of caries incidence. Health effects were estimated in terms of the number of carious lesions and tooth-loss in both the scenarios and modelled as a product of the dose-response relationship between sugar intake and caries incidence. The model was thus used to establish the number of caries lesions prevented, and tooth-loss avoided. Uncertainties in the parameters were assessed using probabilistic sensitivity analysis. The Monte Carlo method was used for simulating the results 999 times.

RESULTS

A 20% rise in the price of sugar is expected to result in the prevention of an average of 1.32 teeth in a lifetime of an individual and prevent 27.96 million tooth-loss incidents among the population cohort of India that will eventually lead to a saving of INR (₹) 3116.32 billion (US$ 42.69 billion) on account of dental caries treatment. Similarly, increasing-price of SSBs by 20% will lead to a 0.86% reduction in carious teeth incidence in an individual's lifetime.

CONCLUSION

Increasing the cost of sugar and/or SSBs will reduce the daily intake of sugar, which will reduce caries incidence and subsequent progression, thereby preventing caries-attributed tooth-loss and saving treatment costs.

In situ evaluation of 200 ppm fluoride toothpaste content trimetaphosphate, xylitol and erythritol on enamel demineralization and dental biofilm

OBJECTIVE

To evaluate the effect of low-fluoride (F^-) toothpaste and sodium trimetaphosphate (TMP) associated with xylitol and erythritol (XE) on enamel demineralization and biofilm composition.

METHODS

This crossover double-blind in situ study consisted of five phases (seven days each), in which 14 volunteers wore oral appliances containing four enamel bovine blocks. The cariogenic challenge was performed by exposure to a 30% sucrose solution (6x/day). The toothpaste treatments (3x/day) were as follows: placebo (no F^-/TMP/XE); 200 ppm F^- (NaF) (200F); 1,100 ppm F^- (1100F); 16% Xylitol and 4% Erythritol (XE); and 200 ppm F^-, 0.2% TMP, 16% xylitol, and 4% erythritol (200F-TMP-XE). Percentage of surface hardness loss (%SH) and integrated loss of subsurface hardness (ΔKHN), and calcium (Ca²⁺), phosphate (PO₄^3-), and F^- on enamel and biofilm were determined; as well as insoluble extracellular polysaccharide (EPS).

RESULTS

XE and 1100F groups showed no significant difference for %SH and ΔKHN values (p = 0.220 and p = 0.886), and the 200F-TMP-XE group had the lowest mineral loss (p < 0.001). Ca²⁺ and PO₄^3- in the enamel showed the highest values (p < 0.001) for the 200F-TMP-XE group. Higher values of F^- in the enamel and biofilm were observed for the 1100F group (p < 0.001). There was no difference for Ca²⁺ (p = 1.00) and EPS (p =0.918) values between XE and 200-TMP-XE groups in the biofilm, but their values were higher and lower than the 1100F (p = 0.002 and p = 0.029), respectively.

CONCLUSIONS

200F-TMP-XE promoted a greater protective effect against enamel demineralization and significantly affected the composition of biofilm formed in situ compared to 1100F toothpaste.

CLINICAL SIGNIFICANCE

Low-F^- toothpaste containing TMP and polyols can be considered an effective and safe measure to improve the oral health of individuals, especially patients with high caries activity.

Relationship between sucrose concentration and bacteria proportion in a multispecies biofilm: : Sucrose challenges to a multispecies biofilm

Objective: The aim of this study was to evaluate the relationship between sucrose concentration and bacteria proportion in a multispecies biofilm model. Methods: Streptococcus mutans (S. mutans), Streptococcus oralis (S. oralis), and Actinomyces naeslundii (A. naeslundii) were chose to form a multispecies biofilm. Different concentration (0-40%) of sucrose was introduced to the multispecies biofilm 3 times per day (30 min per time). And then the bacteria proportion and acid production of the biofilms were analyzed. Results: Increasing sucrose level increased CFU count of S. mutans up to a certain concentration (5% sucrose), after which the number of S. mutans slightly decreased, but the CFU counts of S. oralis and A. naeslundii continually decreased with sucrose concentration increase, especially, from 5% sucrose, the reduction was significant, and S. mutans became the dominant species in the biofilms. Furthermore, the acid production ability of the multispecies biofilm gradually increased and slightly decreased with sucrose concentration increased, and the turning concentration was 5%. Conclusion: Our findings suggest that increasing sucrose level could increase the competitiveness of S. mutans in the multispecies biofilm, which may shift the biofilm to a more cariogenic one, and 5% sucrose formed a most cariogenic biofilm in this study.

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.

Effect of S. mutans combinations with bifidobacteria/lactobacilli on biofilm and enamel demineralization

The present study evaluated the ability of Bifidobacterium and Lactobacillus species associated with streptococci to increase insoluble extracellular polysaccharide (EPS) production and initial caries lesion progression. Bovine enamel blocks (n = 190; 4 mm x 4 mm) were prepared, selected according to initial surface hardness (SH), and divided into two groups: a) double combinations: S. mutans with Bifidobacterium or Lactobacillus, and b) triple combinations: S. mutans and S. sobrinus with Bifidobacterium or Lactobacillus species. The blocks were exposed to the bacterial associations for 7 days. Subsequently, quantity of EPS from biofilms and caries lesion depth were determined by means of colorimetric and cross-sectional enamel hardness (ΔKHN) analysis. The data were submitted to one-way analysis of variance, followed by the Bonferroni test (p < 0.05). S. mutans with B. animalis or B. dentium produced a higher quantity of EPS; S. mutans + B. animalis led to the highest ∆KHN. S. mutans + S. sobrinus + B. longum induced greater EPS and ∆KHN values. In conclusion, associations of B. animalis and B. longum with streptococci promoted EPS production and caries lesion progression.

Targeting implant-associated infections: titanium surface loaded with antimicrobial

Implant devices have = proven a successful treatment modality in reconstructive surgeries. However, increasing rates of peri-implant diseases demand further examination of their pathogenesis. Polymicrobial biofilm formation on titanium surfaces has been considered the main risk factor for inflammatory processes on tissues surrounding implant devices, which often lead to implant failure. To overcome microbial accumulation on titanium surfaces biofilm targeting strategies have been developed to modify the surface and incorporate antimicrobial coatings. Because antibiotics are widely used to treat polymicrobial infections, these agents have recently started to be incorporated on titanium surface. This review discusses the biofilm formation on titanium dental implants and key factors to be considered in therapeutic and preventative strategies. Moreover, a systematic review was conducted on coatings developed for titanium surfaces using different antibiotics. This review will also shed light on potential alternative strategies aiming to reduce microbial loads and control polymicrobial infection on implanted devices.

Dose-Response Effect of Fluoride Dentifrices on De-/Remineralization of Root Dentine in situ

The present study aimed to evaluate the effect of fluoride (F) dentifrice with different F concentrations on root dentine de-/remineralization. Ten healthy volunteers took part in this randomized, double-blinded, cross-over, and split-mouth in situ experimental study. During 4 phases of 7 days, they wore a palatal appliance containing 4 bovine dentine blocks (2 sound and 2 with caries) of 4 × 4 × 2 mm. Treatments were performed with silica-based dentifrices containing 0, 700, 1,300, and 5,000 µg F/g (F as NaF). To provide a cariogenic challenge, a 20% sucrose solution was dripped 3 and 8 times daily on the carious-like and sound blocks, respectively. After each experimental phase, the percentage of surface hardness loss (%SHL) or recovery (%SHR) was calculated and the fluoride concentration in the biofilm was determined. The statistical analysis was performed using ANOVA and the Tukey post hoc test with p at 5%. The relationship between variables was analyzed by linear regression. The results showed a lower %SHL when 5,000 µg F/g dentifrice was used but without a statistically significant difference from the conventional one (1,300 µg F/g). Regarding remineralization and F in biofilms, the high-fluoride dentifrice was expressively superior in mineral replacement on the surface and in the F concentration in the biofilms, respectively, compared to the other 3 products (p < 0.05). Also, a significant linear fit between mineral loss/gain, F in biofilms, and fluoride concentration in the dentifrices could be observed. In conclusion, a dose-response F effect was observed, and the high-fluoride dentifrice was effective in enhancing root dentine remineralization in this short-term in situ study.

Novel Nanocomposite Inhibiting Caries at the Enamel Restoration Margins in an In Vitro Saliva-Derived Biofilm Secondary Caries Model

Secondary caries often occurs at the tooth-composite margins. This study developed a novel bioactive composite containing DMAHDM (dimethylaminohexadecyl methacrylate) and NACP (nanoparticles of amorphous calcium phosphate), inhibiting caries at the enamel restoration margins in an in vitro saliva-derived biofilm secondary caries model for the first time. Four composites were tested: (1) Heliomolar nanocomposite, (2) 0% DMAHDM + 0% NACP, (3) 3% DMAHDM + 0% NACP, (D) 3% DMAHDM + 30% NACP. Saliva-derived biofilms were tested for antibacterial effects of the composites. Bovine enamel restorations were cultured with biofilms, Ca and P ion release of nanocomposite and enamel hardness at the enamel restoration margins was measured. Incorporation of DMAHDM and NACP into composite did not affect the mechanical properties (p > 0.05). The biofilms’ CFU (colony-forming units) were reduced by 2 logs via DMAHDM (p < 0.05). Ca and P ion release of the nanocomposite was increased at cariogenic low pH. Enamel hardness at the margins for DMAHDM group was 25% higher than control (p < 0.05). With DMAHDM + NACP, the enamel hardness was the greatest and about 50% higher than control (p < 0.05). Therefore, the novel composite containing DMAHDM and NACP was strongly antibacterial and inhibited enamel demineralization, resulting in enamel hardness at the margins under biofilms that approached the hardness of healthy enamel.

In vitro evaluation of composite containing DMAHDM and calcium phosphate nanoparticles on recurrent caries inhibition at bovine enamel-restoration margins

OBJECTIVE

Recurrent caries is a primary reason for restoration failure caused by biofilm acids. The objectives of this study were to: (1) develop a novel multifunctional composite with antibacterial function and calcium (Ca) and phosphate (P) ion release, and (2) investigate the effects on enamel demineralization and hardness at the margins under biofilms.

METHODS

Dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) were incorporated into composite. Four groups were tested: (1) Commercial control (Heliomolar), (2) Experimental control (0% DMAHDM + 0% NACP), (3) antibacterial group (3% DMAHDM + 0% NACP), (D) antibacterial and remineralizing group (3% DMAHDM + 30% NACP). Mechanical properties and Ca and P ion release were measured. Colony-forming units (CFU), lactic acid and polysaccharide of Streptococcus mutans (S. mutans) biofilms were evaluated. Demineralization of bovine enamel with restorations was induced via S. mutans, and enamel hardness was measured. Data were analyzed via one-way and two-way analyses of variance and Tukey's multiple comparison tests.

RESULTS

Adding DMAHDM and NACP into composite did not compromise the mechanical properties (P > 0.05). Ca and P ion release of 3% DMAHDM + 30% NACP was increased at cariogenic low pH. Biofilm lactic acid and polysaccharides were greatly decreased via DMAHDM, and CFU was reduced by 4 logs (P < 0.05). Under biofilm acids, enamel hardness at the margins was decreased to about 0.5 GPa for control; it was about 1 GPa for antibacterial group, and 1.3 GPa for antibacterial and remineralizing group (P < 0.05).

CONCLUSIONS

The novel 3% DMAHDM + 30% NACP composite had strong antibacterial effects. It substantially reduced enamel demineralization adjacent to restorations under biofilm acid attacks, yielding enamel hardness that was 2-fold greater than that of control composites. The novel multifunctional composite is promising to inhibit recurrent caries.

On the release of fluoride from biofilm reservoirs during a cariogenic challenge: an in situ study

Biofilm fluoride reservoirs may be a source of fluoride to the fluid phase during a sugar challenge reducing tooth mineral loss. However, the evidence for that is conflicting and has not been studied in biofilms containing different fluoride levels. In order to test fluoride release from biofilms with distinct fluoride concentrations, biofilms were grown in situ exposed to a combination of placebo, calcium and fluoride rinses forming biofilms with no (fluoride-free rinses), low (fluoride-only rinses) or high (calcium followed by fluoride rinses) fluoride concentrations, and collected before and 5 min after a sucrose challenge. Rinsing with fluoride increased fluoride concentration in the biofilm (p < 0.05), mainly when a calcium pre-rinse was used before the fluoride (p < 0.05). However, after a sugar challenge, no significant increase in the biofilm fluid fluoride concentration was observed, even in the fluoride-rich biofilms (p > 0.05). Fluoride-rich biofilms do not release fluoride to the fluid phase during a sugar challenge.

Plaque Fluoride Levels as a Predictor of Caries Development in Early Childhood with High Sugar Exposure - A Preliminary Study

Objective

This longitudinal study aimed to investigate if the plaque fluoride (PF) concentration can predict the early childhood caries onset. Design: As part of a larger study, 188 preschoolers were clinically evaluated for early childhood caries diagnosis, at baseline and after 1-year follow-up. After that, the final sample comprised: 1. children who had already caries at baseline (decayed, missing or filled surfaces, as well as white chalky white spot lesions adjacent to gingival margins) and developed at least one more cavitation after one year (n=16), and 2. children who never had or developed any caries lesions, including active white spots lesions (n=15). Before the clinical examinations, dental plaque was collected. PF concentration was determined with an ion-specific electrode. A chart was used to estimate the mean daily sugar exposure. The results were statistically analyzed by Spearman correlation and logistic regression analyses (α=0.05).

Results

After one year, a positive significant correlation between caries development and liquid sucrose, total sugar and total sucrose consumption increments was found (p<0.05). Moreover, the solid sugar, solid sucrose and total sugar exposure at baseline were positively correlated with the presence of dental plaque at follow-up (p<0.05). To top it all, children with PF concentrations ≤0.1 μg/mg at baseline were 10 times more likely to develop caries.

Conclusion

In conclusion, this study demonstrated for the first time in vivo that low PF concentration is a predictor of caries development in primary teeth.

Effect of high-fluoride dentifrice and bracket bonding composite material on enamel demineralization in situ

OBJECTIVE

This in situ study evaluated the effect of high-fluoride dentifrice (5000 μg F^-/g) and fluoride-containing bonding composite resin on enamel demineralization adjacent to orthodontic brackets.

METHODS

Ten volunteers wore palatal appliances containing bovine enamel blocks with metallic brackets bonded with fluoride-free or fluoride-containing composite resin. During three phases of 14 days each, three dentifrices with different fluoride concentrations (0, 1100, and 5000 μg F^-/g) were tested. The cariogenic challenge consisted of 20% sucrose solution dripped 8x/day onto the dental blocks. At the end of each phase, biofilm formed was collected for fluoride analysis. Cross section hardness was performed in enamel blocks, and the lesion area was calculated. Data were analyzed by two-way ANOVA followed by Tukey post hoc test (α = 5%).

RESULTS

The only signicant factor for all the variables under study was the dentifrice. Smaller lesion area and higher fluoride concentration on biofilm were found in 5000 μg F^-/g group, irrespective of bonding composite resin (p < 0.001). Neither bracket-bonding composite resin nor the interaction between the factors was statistically significant (p > 0.05) for all the variables.

CONCLUSION

High-fluoride dentifrice is effective in reducing demineralization on enamel adjacent to orthodontic brackets, while the fluoride-containing bonding composite resin does not influence it.

CLINICAL SIGNIFICANCE

Since high-fluoride dentifrice was able to reduce demineralization adjacent to brackets, it can be an option to caries management in orthodontics patients.

Targeting S. mutans biofilms: a perspective on preventing dental caries

The prevalence of biofilm diseases, and dental caries in particular, have encouraged extensive research on S. mutans biofilms, including methods of preventing its formation. Numerous small molecules with specific anti-biofilm activity against this pathogen have been isolated and synthesized. Generally, these molecules can be characterized into three categories: sucrose-dependent anti-adhesion, sucrose-independent anti-adhesion and cellular signaling interference. This review aims to provide an overview of the current small molecule strategies used for targeting S. mutans biofilms, and a perspective of the future for the field.

Root dentine demineralisation according to frequency of sucrose exposure using high-fluoride dentifrice

OBJECTIVE

To evaluate root dentine demineralisation, biomass and loosely bound fluoride (CaF₂ ) concentration according to different frequencies of sucrose exposure using a high-fluoride dentifrice.

BACKGROUND

Although high-fluoride dentifrice has been recommended to arrest root dentine lesions, it is not clear whether it can protect dentine from increased frequencies of sucrose exposure.

METHODS

An in situ, crossover, split-mouth study was conducted in 3 phases with 7 days each, in which 10 volunteers used a palatal device containing 4 bovine root dentine slabs (2 on each side) with predetermined initial hardness. Cariogenic challenge consisted in dripping a 20% sucrose solution 0 (control), 2, 4, 6, 8 or 10 times/d in each block. Volunteers used high-fluoride dentifrice (NaF, 5000 µg F/g) 3 times/d. After each phase, final hardness was measured and the percentage of surface hardness loss (%SHL) calculated. Also, biomass and CaF₂ concentration on dentine were determined. The data were processed and analysed by ANOVA and Tukey test with significance level set at 5%. The relationship between the variables was analysed by linear regression and Pearson correlation (r).

RESULTS

%SHL and biomass were significantly greater than control for sucrose frequencies higher than 6 times/d (P < 0.001), while CaF₂ concentration decreased from sucrose frequency higher than 2 times/d (P < 0.001). Regression analysis data showed a significant linear fit between sucrose exposure frequency and the studied variables with a strong correlation (r) for %SHL and CaF₂ and moderate for biomass (P < 0.05).

CONCLUSION

High-fluoride dentifrice is able to reduce root dentine demineralisation if sucrose consumption is not higher than 6 times/d.

Novel dental composite with capability to suppress cariogenic species and promote non-cariogenic species in oral biofilms

Recurrent caries often occurs and is a primary reason for the failure of dental composite restorations. The objectives of this study were to: (1) develop a bioactive composite containing dimethylaminohexadecyl methacrylate (DMAHDM), (2) investigate its antibacterial effects and suppression on biofilm growth, and (3) investigate its ability to modulate biofilm species composition for the first time. DMAHDM was incorporated into a composite at mass% of 0%, 0.75%, 1.5%, 2.25% and 3%. A commercial composite Heliomolar served as a comparative control. A biofilm model consisting of Streptococcus mutans (S. mutans), Streptococcus sanguinis (S. sanguinis) and Streptococcus gordonii (S. gordonii) was tested by growing biofilms for 48 h and 72 h on composites. Colony-forming units (CFUs), metabolic activity and live/dead staining were evaluated. Lactic acid and polysaccharide productions were measured to assess biofilm cariogenicity. TaqMan real-time polymerase chain reaction was used to determine the proportion of each species in the biofilm. DMAHDM-containing composite had a strong anti-biofilm function, reducing biofilm CFU by 2-3 orders of magnitude, compared to control composite. Biofilm metabolic activity, lactic acid and polysaccharides were decreased substantially, compared to control (p < 0.05). At 72 h, the cariogenic S. mutans proportion in the biofilm on the composite with 3% DMAHDM was 19.9%. In contrast, an overwhelming S. mutans proportion of 92.2% and 91.2% existed in biofilms on commercial control and 0% DMAHDM, respectively. In conclusion, incorporating DMAHDM into dental composite: (1) yielded potent anti-biofilm properties; (2) modulated the biofilm species composition toward a non-cariogenic tendency. The new DMAHDM composite is promising for applications in a wide range of tooth cavity restorations to modulate oral biofilm species and combat caries.

Anticaries effect of toothpaste with nano-sized sodium hexametaphosphate

OBJECTIVE

To evaluate the effect of a fluoride toothpaste containing nano-sized sodium hexametaphosphate (HMPnano) on enamel demineralization on the biochemical composition and insoluble extracellular polysaccharide (EPS) in biofilm formed in situ.

METHODS

This crossover double-blind study consisted of four phases (7 days each), in which 12 volunteers wore intraoral appliances containing four enamel bovine blocks. The cariogenic challenge was performed using 30% sucrose solution (6×/day). Blocks were treated 3×/day with the following toothpastes: no F/HMP/HMPnano (Placebo), conventional fluoride toothpaste, 1100 ppm F (1100F), 1100F + 0.5% micrometric HMP (1100F/HMP), and 1100F + 0.5% nano-sized HMP (1100F/HMPnano). The percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), and enamel calcium (Ca), phosphorus (P), and fluoride (F) were determined. Moreover, biofilms formed on the blocks were analyzed for F, Ca, P, and insoluble extracellular polysaccharide (EPS) concentrations. Data were analyzed using one-way ANOVA, followed by Student-Newman-Keuls' test (p < 0.001).

RESULTS

1100F/HMPnano promoted the lowest %SH and ΔKHN among all groups (p < 0.001). The addition of HMPnano to 1100F significantly increased Ca concentrations (p < 0.001). The 1100F/HMPnano promoted lower values of EPS when compared with 1100F (~ 70%) (p < 0.001) and higher values of fluoride and calcium in the biofilms (p < 0.001).

CONCLUSION

1100F/HMPnano demonstrated a greater protective effect against enamel demineralization and on the composition of biofilm in situ when compared to 1100F toothpaste.

CLINICAL RELEVANCE

This toothpaste could be a viable alternative to patients at high risk of caries.

Factors related to dental caries in 10-year-old Vietnamese schoolchildren

BACKGROUND

In Vietnam, research is required to provide a clearer understanding of the factors associated with dental caries. This will allow paediatric dentists and physicians to provide appropriate care to children.

AIM

To determine the factors related to dental caries and to evaluate the association between dental caries and nutritional status in 10-year-old schoolchildren.

METHOD

In 2015, 1,079 10-year-old children were randomly selected from 16 public schools in Ho Chi Minh City. Information on self-reported oral health, dental habits, eating, drinking and physical activity behaviours was obtained via a questionnaire. Anthropometric measurements (height and weight) were also taken. Body mass index (BMI) was calculated, and nutritional classification of children was conducted using the BMI-for-age percentile. Dental plaque and dental caries (decayed and filled teeth) were recorded for both primary and permanent teeth.

RESULTS

Dental caries was experienced on primary and permanent teeth by 60.7% and 39.6%, respectively, of subjects. The factors significantly related to primary tooth decay were school location [odds ratio (OR) = 1.78], self-reported dental caries (OR = 1.36), frequency of tooth self-checking (OR = 1.32), toothbrushing habits (OR = 1.31) and nutritional status (OR = 1.77); however, the factors associated with permanent tooth decay were school location (OR = 2.66), self-reported dental caries (OR = 1.34), frequency of tooth self-checking (OR = 1.37), frequency of dental check-ups (OR = 1.35), toothbrushing habits (OR = 1.31) and nutritional status (OR = 1.39 and 1.74) (P < 0.05).

CONCLUSION

Dental caries was associated with school location, dental-related behaviours and nutritional status in 10-year-old schoolchildren in Ho Chi Minh City, Vietnam.

Effect of sucrose on biofilm formed in situ on titanium material

BACKGROUND

Because sucrose may change the composition of biofilms formed on dental surfaces, the aim of this study was to evaluate in situ the effect of this dietary sugar on biofilm formation on titanium surface.

METHODS

In this blind, crossover, in situ study, 10 volunteers wore, in 3 phases of 7 days each, a palatal appliance containing titanium specimens. In each phase, the specimens were treated extraorally with 20% sucrose solution at a frequency of 4 or 8 times per day. As control, no treatment was rendered (0×). At the end of each phase, the biofilms were collected for biochemical analysis of biofilm wet weight (biomass), protein concentration, soluble (S-EPS), and insoluble (I-EPS) extracellular polysaccharides and intracellular polysaccharides (IPS), and for microbiologic analysis by checkerboard DNA-DNA hybridization (for levels and proportions of 40 bacterial species). Biochemical data were analyzed by linear regression and microbiological findings by Friedman and Dunn tests (α = .05).

RESULTS

A positive significant linear relationship was found among sucrose exposure (0×, 4×, and 8×) and biomass, S-EPS, I-EPS and IPS (p < 0.05). The biofilms treated with sucrose (4× and/or 8×) presented higher mean total levels of the 40 bacterial species evaluated, higher proportions of red complex species and lower proportions of the host-compatible green complex species, in comparison with the control group (p < 0.05).

CONCLUSION

The findings of the present study suggest that daily sucrose exposure has a harmful effect on the composition of biofilms formed on titanium surfaces.

Fluoride Penetration and Clearance Are Higher in Exopolysaccharide-Containing Bacterial Pellets

Extracellular polysaccharides (EPS) could increase the penetration of fluoride through dental biofilm, reducing its cariogenicity. We measured the concentration of fluoride in EPS-containing (EPS+) or not-containing (EPS-) Streptococcus mutans bacterial pellets resembling test biofilms, before and up to 60 min after a 0.05% NaF rinse in situ. Fluoride penetration and clearance were higher in EPS+ bacterial pellets. The data suggest that EPS enhances fluoride penetration, but also accelerates fluoride clearance from dental biofilms.

In situ Effect of Arginine-Containing Dentifrice on Plaque Composition and on Enamel Demineralization under Distinct Cariogenic Conditions

There is limited evidence that arginine-containing fluoridated dentifrices (AFD) have a better anticaries effect than regular fluoridated dentifrices (FD), especially in subjects at a higher risk for caries development. This study aimed to assess the effect of AFD on enamel demineralization and on the microbial and biochemical compositions of biofilm formed under different frequencies of sucrose exposure. It consisted of an in situ split-mouth design, where 12 adult volunteers who used FD for at least 2 months prior to the beginning of this study wore acrylic palatal appliances containing 4 bovine enamel specimens (1 pair at each side of the appliance) during 2 phases of 14 days each. FD slurry (3×/day) and 20% sucrose solution (4× and 8×/day) were dripped on the specimens during the first experimental phase. The same volunteers then used AFD during a 2-month washout period, followed by a second experimental phase where the AFD slurry and sucrose solution were applied onto a new subset of specimens. The percentage of enamel surface hardness loss (%SHL), the lesion depth (LD), the integrated mineral loss (IML), microbial counts on biofilms, the biomass, and inorganic and insoluble extracellular polysaccharide (IEPS) biofilm concentrations were determined. Higher %SHL, biomass, and IEPS and lower fluoride values were found at sucrose 8×/day exposure. Lower IEPS were found in the presence of AFD compared to FD. Similar %SHL, LD, and IML values were found between FD and AFD, irrespectively of the cariogenic challenge. The results suggest that AFD have an anticaries effect similar to that of regular FD.

Ecological Approaches to Dental Caries Prevention: Paradigm Shift or Shibboleth?

Contemporary paradigms of dental caries aetiology focus on the ecology of the dental plaque biofilm and how local environmental factors can modulate this to cause disease. The crucial role that a healthy oral microbiome plays in preventing caries and promoting oral health is also being increasingly recognized. Based on these concepts, several ecological preventive approaches have been developed that could potentially broaden the arsenal of currently available caries-preventive measures. Many of these ecological approaches aim for long-term caries control by either disrupting cariogenic virulence factors without affecting bacterial viability, or include measures that can enhance the growth of health-associated, microbially diverse communities in the oral microbiome. This paper argues for the need to develop ecological preventive measures that go beyond conventional caries-preventive methods, and discusses whether these ecological approaches can be effective in reducing the severity of caries by promoting stable, health-associated oral biofilm communities.

In situ effect of the combination of fluoridated toothpaste and fluoridated gel containing sodium trimetaphosphate on enamel demineralization

OBJECTIVE

This in situ study evaluated the effect of the association of low-F (4500μg F/g) gel containing TMP and FT (1100μg F/g) on enamel demineralization.

METHODS

This crossover and double-blind study consisted of five phases of seven days each. Volunteers (n=12) wore palatal appliances containing four enamel blocks. The cariogenic challenge was performed with 30% sucrose solution (six times/day). Treatments were: placebo toothpaste (PT, no fluoride/TMP); 1100μg F/g toothpaste (FT); FT+4500μg F/g+5%TMP gel (FT+TMP gel); FT+9000μg F/g gel (FT+9000 gel) and FT+12,300μg F/g (FT+Acid gel). After topical application of treatments for one min, two blocks were removed for analysis of loosely bound fluoride (CaF₂), calcium (Ca), phosphorus (P) and firmly bound fluoride (FA) formed in enamel. After the seven-day experimental periods, the percentage of surface hardness loss (%SH), integrated subsurface hardness loss (ΔKHN), CaF₂, Ca, P and FA retained were determined. Moreover, the biofilms formed on the blocks were analyzed for F, Ca, P and insoluble extracellular polysaccharide (EPS) concentrations.

RESULTS

FT+TMP gel promoted the lowest%SH and ΔKHN (p<0.001). The highest concentration of CaF₂ formed was observed for the FT+Acid gel (p<0.001), followed by FT+9000 gel > FT+TMP gel > FT > PT. CaF₂ retained on the blocks was reduced across all groups (p<0.001). Similar values were observed for the Ca/P/F and EPS in enamel and biofilm for all fluoride groups.

CONCLUSION

The association of FT+TMP gel significantly reduced enamel demineralization in situ.

CLINICAL SIGNIFICANCE

The association of treatments may be an alternative for patients with high caries risk.

Sugars and beyond. The role of sugars and the other nutrients and their potential impact on caries

The traditional concept of caries as a multifactorial transmittable and infectious disease has been challenged. Novel conceptual ideas have come to add to the complexity of this highly prevalent disease worldwide. Current etiological understanding of the disease has emphasized the pivotal role of sugars in caries. In fact, current definition points toward an ecological disease caused by the commensal microbiota that under ecological imbalances, mainly due to high and or frequent sugars consumption, creates a state of dysbiosis in the dental biofilm. This modern conceptual idea, however, tends to underrate a key issue. As humans are omnivore and consume a mix diet composed by a multitude of substances, the role of the diet in caries must not be restricted only to the presence of fermentable sugars. This review explores the contribution of other food components, ubiquitous to the diet, mostly as potentially protective factors. Anticaries nutrients might determine an environmental change, affecting the ecology of the oral microbiome and partially mitigating the effect of sugars. Understanding the function of the food usually consumed by the people will contribute new knowledge on the mechanisms associated with the onset of caries, on new caries risk variables and on potential novel strategies for the prevention and treatment of the disease.

Feeding frequency in infancy and dental caries in childhood: a prospective cohort study

OBJECTIVES

Feeding patterns in infancy are plausible contributors to dental caries later in childhood, yet relatively few cohort studies have examined potential dietary risk factors at this age. This study aimed to investigate the associations between feeding frequency at age 12 months and caries prevalence at age 3 years.

METHODS

In this prospective birth cohort of 345 Brazilian children, all foods and drinks consumed at age 12 months, including bottle-use and breastfeeding, were recorded using two 24-hour infant dietary recalls with mothers. The prevalence of early childhood caries (ECC) and severe ECC (S-ECC) at age 38 months were compared in groups defined according to 12-month feeding frequency, using regression models to adjust for sociodemographic characteristics and total carbohydrate intake.

RESULTS

Independent of other variables, compared with children with infrequent bottle-use and breastfeeding at 12 months, at 38 months the ECC prevalence was 1.8-times higher in children breastfed more than three times/day (P = 0.001), 1.4-times higher in children bottle-fed more than three times/day (P = 0.07) and 1.5-times higher with combined high frequency of bottle and breastfeeding together (P = 0.04), but the association with consumption of other foods or drinks more than five times/day [risk ratio (RR) = 1.2; P = 0.10] was not statistically significant. Prevalence of S-ECC was significantly associated with frequent breastfeeding (RR = 2.4; P < 0.001) and with greater frequency of consumption of other foods or drinks (RR = 1.7, P = 0.001).

CONCLUSIONS

High-frequency feeding in late infancy, including both bottle use and breastfeeding, were positively associated with dental caries in early childhood, suggesting possible early-life targets for caries prevention.

Fluoride in saliva and dental biofilm after 1500 and 5000 ppm fluoride exposure

OBJECTIVES

The aim of this randomized, double-blind, crossover study was to measure fluoride in saliva and 7-day-old biofilm fluid and biofilm solids after rinsing three times per day for 3 weeks with 0, 1500, or 5000 ppm fluoride (NaF).

MATERIALS AND METHODS

Following the 3-week wash-in/wash-out period, including 1 week of biofilm accumulation, saliva and biofilm samples were collected from 12 participants immediately before (background fluoride), and 10, 30, and 60 min after a single rinse. Biofilm samples were separated into fluid and solids, and samples were analyzed using a fluoride electrode (microanalysis).

RESULTS

The background fluoride concentration was statistically significantly higher in the 5000 compared to the 1500 ppm F rinse group in all three compartments (22.3 and 8.1 μM in saliva, 126.8 and 58.5 μM in biofilm fluid, and 10,940 and 4837 μmol/kg in biofilm solids). The 1-h fluoride accumulation for the 5000 ppm F rinse was higher than for the 1500 ppm F rinse in all three compartments, although not statistically significant for saliva and biofilm solids.

CONCLUSION

Regular exposure to 5000 ppm fluoride elevates background fluoride concentrations in saliva, biofilm fluid, and biofilm solids compared to 1500 ppm fluoride. Increasing the fluoride concentration almost 3.5 times (from 1500 to 5000 ppm) only elevates the background fluoride concentrations in saliva, biofilm fluid, and biofilm solids twofold.

CLINICAL RELEVANCE

Even though fluoride toothpaste may be diluted by saliva, the results of the present study indicate that use of 5000 ppm fluoride toothpaste might lead to improved caries control.

Fluoride in Dental Biofilm Varies across Intra-Oral Regions

Information on differences in biofilm fluoride concentration across intra-oral regions may help explain the distribution of caries within the dentition. The aim of this cross-sectional study was to describe the fluoride concentration in saliva and in biofilm fluid and biofilm solids across 6 intra-oral regions. Unstimulated whole saliva was collected from 42 participants and biofilm harvested from the buccal sites in the 4 molar and 2 anterior regions. Samples were collected at least 1 h after use of fluoride dentifrice. No attempt was made to control the participants' food consumption or use of other topical agents. Centrifuged saliva, biofilm fluid, and biofilm solids were analysed for fluoride using a fluoride ion-selective electrode, adapted for microanalysis. Fluoride in biofilm varied across intra-oral regions. The mean biofilm fluid fluoride concentrations across the oral cavity ranged from 11.6 to 16.8 µM, being statistically significantly higher in the upper anterior region than in any other region. In all regions the fluoride concentration in biofilm fluid was higher than in saliva. For biofilm solids the fluoride concentration was highest in the lower anterior region (2,461 μmol/kg) and lowest in the lower molar regions (388 and 406 μmol/kg, respectively). Within biofilm, the solids contained most of the fluoride (81 to >99%). The biofilm fluid fluoride concentration was significantly positively associated with salivary fluoride and only marginally associated with that of biofilm solids. In conclusion, this study has shown pronounced differences in fluoride distribution across intra-oral regions and compartments. This shows that the sampling site is a crucial factor for studies of biofilm fluoride.

Role of Candida species from HIV infected children in enamel caries lesions: an in vitro study

Objectives

This study analyzed the capacity of Candida spp. from dental biofilm of HIV infected (HIV+) children to demineralize primary molar enamel in vitro by Transversal Microhardness (TMH), Polarized Light Microscopy (PLM) and the quantity of calcium ions (Ca²⁺) released from the enamel.

Material and Methods

Candida spp. samples were isolated from the supragingival biofilm of HIV+ children. A hundred and forty (140) enamel blocks were randomly assigned to six groups: biofilm formed by C. albicans (Group 1); mixed biofilm formed by C. albicans and C. tropicalis (Group 2); mixed biofilm formed by C. albicans and C. parapsilosis (Group 3); mixed biofilm formed by C. albicans, C. parapsilosis and C. glabrata (Group 4); biofilm formed by C. albicans ATCC (Group 5) and medium without Candida (Group 6). Enamel blocks from each group were removed on days 3, 5, 8 and 15 after biofilm formation to evaluate the TMH and images of enamel were analyzed by PLM. The quantity of Ca²⁺ released, from Groups 1 and 6, was determined using an Atomic Absorption Spectrophotometer. The SPSS program was used for statistical analysis and the significance level was 5%.

Results

TMH showed a gradual reduction in enamel hardness (p<0.05) from the 1^st to 15^th day, but mainly five days after biofilm formation in all groups. The PLM showed superficial lesions indicating an increase in porosity. C. albicans caused the release of Ca²⁺ into suspension during biofilm formation.

Conclusion

Candida species from dental biofilm of HIV+ children can cause demineralization of primary enamel in vitro.

Toothpaste with Nanosized Trimetaphosphate Reduces Enamel Demineralization

This double-blind crossover study assessed the effects of a low-fluoride (low-F) dentifrice containing nanosized sodium trimetaphosphate (TMP) on enamel demineralization in situ. Nineteen subjects wore palatal appliances containing 4 blocks of bovine enamel and were randomly assigned to brush their teeth with placebo (without F/TMP), 250-ppm F (250F), 250F plus 0.05% nanosized TMP (250F-TMPnano), and 1,100-ppm F (1,100F) dentifrices during 7 d, under cariogenic challenge. Enamel surface hardness and cross-sectional hardness (ΔKHN [Knoop hardness number]), as well as F, calcium (Ca), and phosphorus (P) concentrations, were determined. Also, biofilm that formed on the blocks was analyzed for F, Ca, P, and insoluble extracellular polysaccharide concentrations. Data were submitted to analysis-of-variance models and Student-Newman-Keuls test ( P < 0.05). The 250F-TMPnano dentifrice promoted the lowest ΔKHN among all groups ( P < 0.001), while the percentage of surface hardness loss was similar to 1,100F. Also, similar F, Ca, and P concentrations in enamel were observed for 1,100F and 250F-TMPnano. In the biofilm, the highest F content was observed for 1,100F; Ca content was similar between 1,100F and 250F-TMPnano; and P content was similar among all groups. Similar extracellular polysaccharide values were observed for 250F-TMPnano and 1,100F ( P < 0.001), ionic activity of CaHPO40, CaF+, and HF0 ( P < 0.05) and degree of saturation of hydroxyapatite and CaF2 ( P < 0.05). It was concluded that the protective effect of 250F-TMPnano dentifrice was similar to a conventional dentifrice for most of the variables studied, having a more pronounced effect on the subsurface lesion when compared with the conventional toothpaste (1,100F).

Knowledge Transfer Statement: Although toothpastes containing ≥1,000-ppm fluoride are more effective than low-fluoride formulations against dental caries, their early use can lead to side effects. This has prompted intensive research on alternatives to increase the anticaries effect of low-fluoride toothpastes. The present in situ study demonstrated that the addition of sodium trimetaphosphate nanoparticles to toothpastes containing 250-ppm fluoride significantly enhances the protective effect of this formulation against enamel demineralization to levels comparable to a 1,100-ppm fluoride toothpaste in terms of most of the variables studied. Most important, this formulation promoted the lowest loss of subsurface hardness among all groups, suggesting that caries lesions would take longer to develop under clinical conditions when compared with a conventional (1,100-fluoride) toothpaste.

Tooth demineralization and associated factors in patients on fixed orthodontic treatment

Dental demineralization was determined in patients at three time points during fixed orthodontic treatment. A multiple cross-sectional study included 108 patients divided into three different groups: (1) beginning of orthodontic treatment; (2) one year into treatment; and (3) two years into treatment. Demineralization was estimated using a DIAGNOdent pen. We obtained data from multiple tooth-by-tooth demineralization readings combined with salivary pH and patients' oral hygienic and dietary behaviors. A t-test for independent samples and Spearman´s correlation were performed. No demineralizations differences were found between the initial stage and one year into treatment. Between one and two years small differences were observed, but demineralization increased between the initial stage and second treatment year, predominating in upper right central incisors (p = 0.056), upper left lateral incisors (p = 0.040), both upper canines (p = 0.055 and p = 0.040, respectively) and first left premolars (p = 0.034 and p = 0.053, respectively). We did not find associations between oral hygiene and dietary behaviours or salivary pH. In conclusion, demineralization occurred in first year of treatment and increased during second year, predominating in the upper arch and the left side mainly in upper right central incisors, upper left lateral incisors, both upper canines, and first left premolars.

Effect of Fluoride Concentration on Reduction of Enamel Demineralization According to the Cariogenic Challenge

Abstract Fluoride present in toothpaste at 1,100 µg/g is considered effective on caries control. However, under high cariogenic challenge due to increasing sugar exposure, higher fluoride concentration (5,000 µg/g) could be necessary to compensate the unbalance on caries process. This was tested in a pH-cycling regimen, which evaluated the effect of fluoride concentration relative to toothpaste on reduction of enamel demineralization under conditions of two levels of cariogenic challenge. Enamel slabs (n=20) were subjected to two pH-cycling regimens, simulating 8x and 16x/day sugar exposure and were treated with solutions containing: 0 (no fluoride), 275 or 1,250 µg F/mL, resulting in 6 treatment groups: 4-h/0-F; 8-h/0-F; 4-h/275-F; 8-h/275-F; 4-h/1,250-F and 8-h/1,250-F. The 275 and 1,250 µg F/mL concentrations simulate mouth salivary dilution when 1,100 and 5,000 µg/g toothpastes are used. Enamel demineralization was assessed by surface (%SHL) and cross-sectional hardness. Fluoride taken up by enamel was also evaluated. Data were analyzed by ANOVA one-way and Tukey's test. The treatment with 1,250 µg F/mL significantly reduced %SHL compared with 275 µg F/mL (p<0.05), irrespective the level of cariogenic challenge (4-h/1,250-F vs. 4-h/275-F and 8-h/1,250-F vs 8-h/275-F comparisons, respectively). These data were supported by fluoride concentration found in enamel. These findings suggest that higher fluoride concentrations could partly compensate the greater caries risk under higher cariogenic challenge due to increasing sugar exposure.

Frequency of sucrose exposure on the cariogenicity of a biofilm-caries model

OBJECTIVE

Although sucrose is considered the most cariogenic carbohydrate in the human diet, the question of how many exposures are needed to induce damage on the hard dental tissues remains unclear. To approach this question, different frequencies of daily sucrose exposure were tested on a relevant biological caries model.

MATERIALS AND METHODS

Biofilms of the Streptococcus mutans were formed on enamel slabs and exposed to cariogenic challenges with 10% sucrose for 5 min at 0, 1, 3, 5, 8, or 10 times per day. After 5 days, biofilms were retrieved to analyze biomass, protein content, viable bacteria, and polysaccharide formation. Enamel demineralization was evaluated by percentage of microhardness loss (percentage surface hardness loss [%SHL]).

RESULTS

Biomass, protein content, polysaccharide production, acidogenicity of the biofilm, and %SHL proportionally increased with the number of daily exposures to sucrose (P < 0.05). One daily sucrose exposure was enough to induce 20% more demineralization than the negative unexposed control. Higher frequencies induced greater demineralization and more virulent biofilms, but eight and ten exposures were not different between them in most of the analyzed variables (P > 0.05).

CONCLUSIONS

Higher sucrose exposure seems to increase cariogenicity, in a frequency-dependent manner, by the modification of bacterial virulent properties.

Calcium Prerinse before Fluoride Rinse Reduces Enamel Demineralization: An in situ Caries Study

A calcium (Ca) prerinse before a fluoride (F) rinse has been shown to increase oral F levels. We tested the anticaries effect of this combination in a dose-response in situ caries model. In a double-blind, crossover experiment, 10 volunteers carried enamel slabs in palatal appliances for 14 days, during which they rinsed twice/day with one of four rinse combinations: (1) a placebo prerinse (150 mM sodium lactate) followed by a distilled water rinse (negative control); (2) a placebo prerinse followed by a 250 ppm F rinse; (3) a placebo prerinse followed by a 1,000 ppm F rinse, or (4) a Ca prerinse (150 mM Ca, as calcium lactate) followed by a 250 ppm F rinse. Sucrose solution was dripped onto the slabs 8×/day to simulate a high cariogenic challenge. The percent surface hardness loss (%SHL) was significantly lower in the Ca prerinse used with the 250 ppm F rinse group (%SHL = 38.0 ± 21.0) when compared with the F rinse alone (%SHL = 59.5 ± 24.1) and similar to the 1,000 ppm F rinse group (%SHL = 42.0 ± 18.3). Compared with the 250 ppm F rinse, the Ca prerinse increased biofilm fluid F only twice (nonsignificant). However, it greatly increased F in biofilm solids (∼22×). The Ca prerinse had little effect on loosely or firmly bound enamel F. The results showed an increased level of protection against demineralization by the use of a Ca prerinse, which seems to be caused by the enhancement of F concentration in the biofilm.

Functional Relationship between Sucrose and a Cariogenic Biofilm Formation

Sucrose is an important dietary factor in cariogenic biofilm formation and subsequent initiation of dental caries. This study investigated the functional relationships between sucrose concentration and Streptococcus mutans adherence and biofilm formation. Changes in morphological characteristics of the biofilms with increasing sucrose concentration were also evaluated. S. mutans biofilms were formed on saliva-coated hydroxyapatite discs in culture medium containing 0, 0.05, 0.1, 0.5, 1, 2, 5, 10, 20, or 40% (w/v) sucrose. The adherence (in 4-hour biofilms) and biofilm composition (in 46-hour biofilms) of the biofilms were analyzed using microbiological, biochemical, laser scanning confocal fluorescence microscopic, and scanning electron microscopic methods. To determine the relationships, 2nd order polynomial curve fitting was performed. In this study, the influence of sucrose on bacterial adhesion, biofilm composition (dry weight, bacterial counts, and water-insoluble extracellular polysaccharide (EPS) content), and acidogenicity followed a 2nd order polynomial curve with concentration dependence, and the maximum effective concentrations (MECs) of sucrose ranged from 0.45 to 2.4%. The bacterial and EPS bio-volume and thickness in the biofilms also gradually increased and then decreased as sucrose concentration increased. Furthermore, the size and shape of the micro-colonies of the biofilms depended on the sucrose concentration. Around the MECs, the micro-colonies were bigger and more homogeneous than those at 0 and 40%, and were surrounded by enough EPSs to support their structure. These results suggest that the relationship between sucrose concentration and cariogenic biofilm formation in the oral cavity could be described by a functional relationship.

Frequency of Fluoride Dentifrice Use and Caries Lesions Inhibition and Repair

The clinical relevance of the frequency of fluoride dentifrice (FD) use on enamel caries is based on evidence. However, the relative effect of FD on reduction of demineralization or enhancement of remineralization is unknown and the effect of frequency on root dentine caries has not been explored. The aim of this double-blind, crossover, in situ study, which was conducted in 4 phases of 14 days each, was to evaluate the relationship between the frequency of FD use and enamel and root dentine de- and remineralization. Eighteen volunteers wore palatal appliances containing enamel and root dentine slabs, either sound or carious. Biofilm accumulation on the slab surface was allowed, and 20% sucrose solution was dripped 3 or 8 times per day on the carious and sound slabs, respectively. Volunteers used FD (1,100 μg F/g) in the frequencies 0 (fluoride-placebo dentifrice), 1, 2 and 3 times per day. The demineralization and remineralization that occurred in sound or carious slabs was estimated by the percentage of surface hardness loss (%SHL) or recovery (%SHR). Loosely (CaF2) and firmly (FAp) bound fluoride concentrations were also determined. The relationship between the variables was analyzed by linear regression. The %SHL, CaF2 and FAp concentrations were a function of the frequency of FD use for enamel and dentine, but the %SHR was a function of the frequency of FD use only for enamel (p < 0.05). The results suggest that demineralization in enamel and root dentine is reduced in proportion to the frequency of FD use, but for remineralization the effect of the frequency of FD use was relevant only to enamel.

Monitoring of caries disease by risk assessments and activity

ABSTRACT Dental caries is a non-communicable disease and is considered a public health problem. For diagnosis and correct treatment, the study of risk assessment and caries activity is necessary. The caries risk assessment is a way to formalize the balance and imbalance of predictably disease to diagnose dental caries. Therefore, the caries risk assessment is performed through different evaluation systems. Another parameter of great importance to be studied is the activity of caries, because through it is done the correct treatment decision for the patient. The objective of this article is to inform the reader about: the concepts and caries risk factors; the different caries risk assessment systems described in the literature; and which systems are validated. In addition, this literature review provides for identification and evaluation of risk factors and activity of caries lesions in order to enable greater objectivity in the diagnosis and facilitate the decisions of a successful treatment.

Effect of dietary sugars on dual-species biofilms of Streptococcus mutans and Streptococcus sobrinus – a pilot study

Abstract Introduction Frequent consumption of sugars and the presence of Streptococcus mutans and Streptococcus sobrinus are correlated with higher caries experience. Objective The aim of this pilot study was to elucidate the effect of different fermentable carbohydrates on biomass formation and acidogenicity of S. mutans and S. sobrinus biofilms. Material and method Single and dual-species biofilms of S. mutans ATCC 25175 and S. sobrinus ATCC 27607 were grown at the bottom of microtiter plates at equal concentrations for 24 h at 37 °C under micro-aerobic atmosphere. Carbohydrates were added at 2% concentration: maltose, sucrose, glucose and lactose. BHI Broth (0.2% glucose) was used as negative control. Acidogenicity was assessed by measuring the pH of spent culture medium after 24 h, immediately after refreshing the culture medium and for the next 1 h and 2 h. Crystal violet staining was used as an indicator of the total attached biofilm biomass after 24 h incubation. Data were analyzed by two-way ANOVA followed by Bonferroni post hoc test. Significance level was set at 5%. Result All carbohydrates resulted in higher biomass formation in single- and dual-species biofilms when compared to the control group. Sucrose, lactose and maltose showed higher acidogenicity than the control group in both single- and dual-species biofilms after 24 h. Conclusion These findings indicate that the type of biofilm (single- or dual-species) and the carbohydrate used may influence the amount of biomass formed and rate of pH reduction.

Evaluation of caries-associated virulence of biofilms from Candida albicans isolated from saliva of pediatric patients with sickle-cell anemia

A previous study demonstrated that the amount of Candida spp. in saliva is higher in children with sickle-cell disease. The results from a recent study demonstrate its participation in the etiology of dental caries.

Diet and Dental Caries: The Pivotal Role of Free Sugars Reemphasized

The importance of sugars as a cause of caries is underemphasized and not prominent in preventive strategies. This is despite overwhelming evidence of its unique role in causing a worldwide caries epidemic. Why this neglect? One reason is that researchers mistakenly consider caries to be a multifactorial disease; they also concentrate mainly on mitigating factors, particularly fluoride. However, this is to misunderstand that the only cause of caries is dietary sugars. These provide a substrate for cariogenic oral bacteria to flourish and to generate enamel-demineralizing acids. Modifying factors such as fluoride and dental hygiene would not be needed if we tackled the single cause--sugars. In this article, we demonstrate the sensitivity of cariogenesis to even very low sugars intakes. Quantitative analyses show a log-linear dose-response relationship between the sucrose or its monosaccharide intakes and the progressive lifelong development of caries. This results in a substantial dental health burden throughout life. Processed starches have cariogenic potential when accompanying sucrose, but human studies do not provide unequivocal data of their cariogenicity. The long-standing failure to identify the need for drastic national reductions in sugars intakes reflects scientific confusion partly induced by pressure from major industrial sugar interests.

Can insoluble polysaccharide concentration in dental plaque, sugar exposure and cariogenic microorganisms predict early childhood caries? A follow-up study

BACKGROUND

Insoluble polysaccharide (IP) has been associated with caries prevalence in young children. However, the power of IP to predict ECC needs to be demonstrated.

AIMS

To assess the relationships between early childhood caries (ECC) and extracellular insoluble polysaccharides (IP) in dental plaque, sugar exposure and cariogenic microorganisms.

DESIGN

Visible plaque on maxillary incisors was recorded, followed by caries diagnosis in 65 preschoolers (3-4 years) at baseline and after 1 year. Plaque was collected for mutans streptococci (MS), total microorganism (TM) and lactobacilli (LB) enumerations in selective media, as well as for IP analysis, which was later assessed by colorimetry. Sugar/sucrose exposure was assessed by a diet chart.

RESULTS

Positive correlations were found among the prevalence of caries and MS, TM, LB, solid sucrose and visible dental plaque. Additionally, children with IP concentrations in dental plaque higher than 2.36 μg/mg (odds ratio-OR=6.8), with visible plaque on maxillary incisors (OR=4.3), harbouring LB (OR=13) and exposed to solid sugar more than twice/day (OR=5) showed higher risk of developing caries (p<0.05).

CONCLUSION

Extracellular insoluble polysaccharides, solid sugar/sucrose, visible dental plaque and cariogenic microorganisms could predict caries development, partially explaining the ECC pattern.

Oral health concerns with sweetened medicaments: Pediatricians' acuity

BACKGROUND

Administration of sweetened medicaments poses many oral health related problems in children due to the lack of awareness among the pediatricians regarding their ill effects.

PURPOSE

To assess pediatricians' awareness and attitudes toward the use of liquid pediatric medicines and their relationship with dental caries and erosion.

MATERIALS AND METHODS

A cross-sectional descriptive study was conducted among the pediatricians residing in Nellore city. Data were obtained from 55 pediatricians using questionnaires.

RESULTS

Among the respondents, 95.6% prescribed liquid medicaments, 51.1% expressed that they may be associated with dental effects, 60% were not aware regarding the sweetness of medicaments, whereas majority of them (77.8%) opined that children complained regarding the taste, 73.3% stated that sugar substitutes were used as sweetening agents, 70.9% believed that they were not acidic, 68.9% did not recommend brushing after intake of medicines, 90% failed to deliver oral health instructions, and 54.5% believed that lack of oral hygiene was a contributing factor for development of dental caries.

CONCLUSION

Majority of the respondents prescribed liquid medicaments and were unaware regarding the sweetening agents and acidity, which cause ill effects on the dental hard tissues. Most of them neither recommended nor delivered oral hygiene instructions (OHI) after prescribing sweetened liquid medicaments. Hence, OHI should be delivered to enhance the oral health related quality of life in children.