Surface properties and Streptococcus mutans - Streptococcus sanguinis adhesion of fluorotic enamel

New Generation of Orthodontic Elastomeric Ligature to Prevent Enamel Demineralization In Vivo

This study aimed to synthesize a novel elastomeric ligature with dimethylaminohexadecyl methacrylate (DMAHDM) grafted, providing a new strategy for improving the issue of enamel demineralization during fixed orthodontics. DMAHDM was incorporated into elastomeric ligatures at different mass fractions using ultraviolet photochemical grafting. The antibacterial properties were evaluated and the optimal DMAHDM amount was determined based on cytotoxicity assays. Moreover, tests were conducted to evaluate the in vivo changes in the mechanical properties of the elastomeric ligatures. To assess the actual in vivo effectiveness in preventing enamel demineralization, a rat demineralization model was established, with analyses focusing on changes in surface microstructure, elemental composition, and nanomechanical properties. Elastomeric ligatures with 2% DMAHDM showed excellent biocompatibility and the best antibacterial properties, reducing lactic acid production by 65.3% and biofilm bacteria by 50.0% within 24 h, without significant mechanical property differences from the control group (p > 0.05). Most importantly, they effectively prevented enamel demineralization in vivo, enhancing elastic modulus by 73.2% and hardness by 204.8%. Elastomeric ligatures incorporating DMAHDM have shown great potential for application in preventing enamel demineralization, providing a new strategy to solve this issue during fixed orthodontics.

Alleviation of dental caries by use of isolated potential probiotic and its characterization

Streptococcus mutans plays a major role in biofilm formation and pathogenic bacterial adhesion. Here we investigated the abilities of our isolates from diverse conventional sources to characterize the beneficial bacteria for inhibition of S. mutans. Enterobacter cloacae PS-74, a beneficial bacteria isolated from yoghurt, is gram negative, rod shaped, and resistant to acid, bile salt, and amylase. PS-74 cell-free supernatants (CFS) demonstrated highest zone of inhibition of 29 ± 1.7 mm. Further, the minimum inhibitory concentration (MIC) value of CFS PS-74 was recorded to be 10 μL and its minimum bactericidal concentration (MBC) value was found to be 15μL which led to 99.9% log reduction of S. mutans. Moreover, the biofilm formation was reduced by 84.91% at MIC15 of CFS PS-74 which alleviate the dental caries formation by S. mutans. This is the first report on E. cloacae PS-74, which was studied for its probiotic properties to inhibit S. mutans MTCC-890 due to the production of organic acids and employed in oral treatment.

Susceptibility of fluorotic enamel to dental erosion-abrasion

Dental hard tissue conditions can be of pre- or post-eruptive nature, such as enamel fluorosis and erosive tooth wear (ETW), respectively. Dental enamel fluorosis is caused by the chronic and excessive intake of fluoride during enamel development, leading to increased fluoride concentration and increased porosity. ETW has become a common clinical condition and often impairs dental function and aesthetics. This in vitro study tested the hypothesis that fluorotic enamel presents different susceptibility to dental erosion-abrasion. It consisted of a 3×3×2 factorial design, considering a) fluorosis severity: sound (TF0), mild (TF1-2), moderate (TF3-4); b) abrasive challenge: low, medium, and high; and c) erosive challenge: yes or no. A total of 144 human teeth were selected according to the three fluorosis severity levels (n=48), and subdivided into six groups (n = 8) generated by the association of the different erosive and abrasive challenges. Enamel blocks (4×4 mm) were prepared from each tooth and their natural enamel surfaces subjected to an erosion-abrasion cycling model. After cycling, the depth of the lesions in enamel was assessed by profilometry. ANOVA showed that the three-way and two-way interactions among the factors were not significant (p > 0.20). Enamel fluorosis level (p=0.638) and abrasion level (p = 0.390) had no significant effect on lesion depth. Acid exposure caused significantly more enamel surface loss than water (p < 0.001). Considering the limitations of this in vitro study, fluorosis did not affect the susceptibility of enamel to dental erosion-abrasion.

Saliva microbiome alterations in dental fluorosis population

Background

We aimed to explore saliva microbiome alterations in dental fluorosis population.

Methods

The prevalence of dental fluorosis was examined in 957 college students. Dean's fluorosis index was used to evaluate the dental fluorosis status. Changes in the composition of the salivary microbiome were assessed in a subset of these patients (100 healthy controls, 100 dental fluorosis patients).

Results

Dental fluorosis affected 47% of the student sample, and incidence was unrelated to gender. Compared with healthy controls, the microbiota of patients with dental fluorosis exhibited increased diversity, with increased abundance of Treponema lecithinolyticum, Vibrio metschnikovii, Cupriavidus pauculus, Pseudomonas, Pseudomonadaceae, Pseudomonadales, and decreased abundance of Streptococcus mutans, Streptococcus sanguinis, Gemella, and Staphylococcales. Function analyses showed increases in arginine biosynthesis in patients affected by dental fluorosis, together with reductions in amino sugar and nucleotide sugar metabolism, fructose and mannose metabolism, and starch and sucrose metabolism.

Conclusions

These results suggest that there are striking differences in salivary microbiome between healthy controls and dental fluorosis patients. Dental fluorosis may contribute to periodontitis and systemic lung diseases. There is a need for cohort studies to determine whether altering the salivary microbiota in dental fluorosis patients can alter the development of oral or systemic diseases.

Effect of Surface Roughness of Deciduous and Permanent Tooth Enamel on Bacterial Adhesion

The adhesion of some bacteria has been attributed to critical levels of roughness in hard tissues, which increases the risk of developing caries. The objective of this work was to assess the effect of deciduous and permanent tooth enamel surface roughness on bacterial adhesion. One hundred and eight samples of deciduous and permanent enamel were divided into two groups (n = 54). G1_DE deciduous enamel and G2_PE permanent enamel. The surface roughness was measured by profilometry and atomic force microscopy (AFM). Subsequently, the evaluation of bacterial adherence was carried out in triplicate by means of the XTT cell viability test. Additionally, bacterial adhesion was observed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The average values of the micrometric roughness in both groups were similar; however, in the nanometric scale they presented significant differences. Additionally, the G1_DE group showed the highest amount of adhered S. mutans and S. sanguinis compared to the G2_EP group. Although the roughness of deciduous and permanent enamel showed contrasting results according to the evaluation technique (area and scale of analysis), bacterial adhesion was greater in deciduous enamel; hence, enamel roughness may not be a determining factor in the bacterial adhesion phenomenon.

Effects of Charcoal Toothpaste on the Surface Roughness, Color Stability, and Marginal Staining of Resin Composites

OBJECTIVE

This study was designed to evaluate the effects of charcoal toothpaste on the surface roughness, color stability, and marginal staining of resin composite restorations.

METHODS

A total of 100 bovine incisors was collected. The crowns were sectioned and randomly divided into 10 groups (n=10) according to two study factors: toothpaste groups and nanoparticle resin composite groups. Five toothpastes-Bianco Pro Clinical (Bianco Oral Care, Uberlândia, MG, Brazil) - Control group; Bianco Carbon (Bianco Oral Care); NAT, Natural Suavetex Carvão Ativado (Suavetex, Uberlândia, MG, Brazil); Nano Action Black Be Emotion (Polishop, Jundiaí, SP, Brazil); and BIW, Black is White (Curaprox, Curaden AG, Kriens, Switzerland)-and two resin composites-Z350XT, Filtek Z350XT (3M Oral Care) and Vittra, Vittra APS (FGM, Joinville, SC, Brazil)-were used. Circular cavities with a diameter of 4 mm and a depth of 1 mm were prepared on the buccal face of the tooth crowns and restored with resin composites. The specimens were subjected to three months of simulated toothbrushing. The surface roughness (right angle [Ra], in micrometers [μm]) of the resin composites was measured before and after toothbrushing in five areas per specimen. The resin composite color and luminosity changes (ΔE and ΔL, respectively) were measured using reflectance spectroscopy (Vita EasyShade). Macro photographs were taken before and after toothbrushing to qualitatively analyze the marginal staining (MSt) of the resin composite restorations. Scanning electron microscopy (SEM) was performed before and after the simulated toothbrushing. Ra data were analyzed using two-way analysis of variance with repeated measures and the Tukey HSD test; MSt was analyzed using Kruskal-Wallis and Dunn tests (α=0.05), and the resin composite color change was analyzed using the clinically unacceptable level of ΔE > 3.3.

RESULTS

Simulated brushing increased Ra irrespective of the resin composite or toothpaste used. No significant differences were found in Ra between the control group and all groups on which the charcoal toothpastes were tested. A clinically unacceptable level of resin composite color change (ΔE>3.3) was found after the use of most charcoal toothpastes. Use of Bianco Carbon resulted in marginal staining similar to that of the control group and was lower than that of the other charcoal toothpastes. Vittra brushed with black toothpaste showed the highest marginal staining.

CONCLUSION

Use of charcoal toothpaste resulted in Ra values of resin composites similar to those found with conventional toothpastes. Charcoal toothpaste generally resulted in clinical resin composite color changes (ΔE). All charcoal toothpastes, except Bianco Carbon, caused marginal staining of the resin composite restorations.

A Qualitative and Comprehensive Analysis of Caries Susceptibility for Dental Fluorosis Patients

Dental fluorosis (DF) is an endemic disease caused by excessive fluoride exposure during childhood. Previous studies mainly focused on the acid resistance of fluorotic enamel and failed to reach a consensus on the topic of the caries susceptibility of DF patients. In this review, we discuss the role of DF classification in assessing this susceptibility and follow the “four factors theory” in weighing the pros and cons of DF classification in terms of host factor (dental enamel and saliva), food factor, bacteria factor, and DF treatment factor. From our analysis, we find that susceptibility is possibly determined by various factors such as the extent of structural and chemical changes in fluorotic enamel, eating habits, fluoride levels in diets and in the oral cavity, changes in quantity and quality of saliva, and/or oral hygiene. Thus, a universal conclusion regarding caries susceptibility might not exist, instead depending on each individual’s situation.