Fluoride varnish containing chitosan demonstrated sustained fluoride release

Analysis of dentin wear and biological properties promoted by experimental inoffice desensitizing materials

BACKGROUND

This study aimed to evaluate dentin wear and biological performance of desensitizing materials.

METHODS

Seventy bovine root dentin blocks were sectioned. Half of the surface of each specimen was untreated (control) and the other half was immersed in EDTA and treated with the following desensitizing materials: placebo varnish (PLA), fluoride varnish (FLU), sodium fluoride (NaF) varnish + sodium trimetaphosphate (TMP), universal adhesive (SBU), S-PRG varnish (SPRG), biosilicate (BIOS), and amelotin solution (AMTN). After application, the specimens were submitted to an erosive-abrasive challenge and the wear analyzed by optical profilometer. Serial dilutions of extracts obtained from the culture medium containing discs impregnated with those desensitizers were applied on fibroblasts and odontoblasts-like cells cultures. Cytotoxicity and production of total protein (TP) by colorimetric assays were determined after 24 h. Data were statistically analyzed using Kruskal-Wallis, Dunn's, One-way ANOVA and Tukey tests (p ≤ 0.05).

RESULTS

No dentin wear was observed only for SBU. The lowest dentin wear was observed for AMTN and TMP. Cell viability was significantly reduced after treatment with undiluted extracts of PLA, FLU, TMP and SBU in fibroblasts and TMP and SBU in odontoblast-like cells. SPRG, BIOS and AMTN were cytocompatible at all dilutions tested. Considering TP results, no statistical difference was observed among the groups and high levels for TP were observed after TMP and FLU treatments.

CONCLUSIONS

Universal adhesive system may protect dentin with opened tubules from wear after challenge. Extracts of adhesive and fluoride varnishes presented cytotoxic mainly on fibroblasts. The enamel protein may be a future alternative to treat dentin with opened tubules because it may cause low wear under erosive-abrasive challenge with low cytotoxic effects.

Investigating the efficacy of a varnish containing gallic acid on remineralization of enamel lesions: an in vitro study

This study evaluated the efficacy of a formulated remineralizing gallic acid (GA) varnish in treating artificial enamel caries lesions. Fifty-five intact bovine incisors were collected. Enamel blocks (5 × 9 mm) were prepared. A third of each block's surface remained intact. Primary carious lesions were induced on the middle and bottom thirds of the blocks by immersing the samples in a demineralization solution for 6 h. The bottom third of the blocks were further remineralized by randomly applying 0.5%, 2%, or 8% GA varnishes and 2.26% fluoride varnish (V varnish, Vericom, Seoul, Korea), or the varnish base without active ingredients (n = 11 each). The specimens were immersed in a remineralizing solution for 4 h and then subjected to a 2-hour immersion in the demineralizing solution. After six days of pH cycling, the surface microhardness was measured at depths of 30, 75, and 120 μm. The percentage of surface microhardness recovery (SMHR%) was compared among the groups using the Shapiro-Wilk, ANOVA, and Tukey HSD post-hoc tests (α = 0.05). The SMHR% of all experimental groups was higher than the control group at 30 μm (p < 0.05). The 0.5% GA varnish showed the highest SMHR% at all depths; however, the difference with the other experimental groups was significant at a depth of 30 μm (p < 0.05). The SMHR% of the fluoride and the 2% and 8% GA varnishes was comparable at all depths. All treatments potentially remineralize enamel lesions, with 0.5% GA varnish having the greatest effect, particularly on the top surface layer. As such, this newly developed varnish may emerge as a promising alternative to fluoride varnish.

Preparation and characterization of a nanohydroxyapatite and sodium fluoride loaded chitosan-based in situ forming gel for enamel biomineralization

The development of remineralizing smart biomaterials is a contemporary approach to caries prevention. The present study aimed at formulation preparation and characterization of a thermoresponsive oral gel based on poloxamer and chitosan loaded with sodium fluoride (NaF) and nanohydroxyapatite (nHA) to treat demineralization. The chemical structure and morphology of the formulation were characterized using FTIR and FESEM-EDS tests. Hydrogel texture, rheology, and stability were also examined. The hydrogel was in a sol state at room temperature and became gel after being placed at 37 °C with no significance different in gelation time with the formulation without nHA and NaF as observed by t-test. The FTIR spectrum of nHA/NaF/chitosan-based hydrogel indicated the formation of physical crosslinking without any chemical interactions between the hydrogel components. The FESEM-EDS results demonstrated the uniform distribution of each element within the hydrogel matrix, confirming the successful incorporation of nHA and NaF in the prepared gel. The hardness, hydrogel's adhesiveness, and cohesiveness were 0.9 mJ, 1.7 mJ, and 0.37, respectively, indicating gel stability and the acceptable retention time of hydrogels. The formulation exhibited a non-Newtonian shear-thinning pseudoplastic and thixotropic behavior with absolute physical stability. Within the limitation of in vitro studies, nHA/NaF/chitosan-based in situ forming gel demonstrated favorable properties, which could be trasnsorm into a gel state in oral cavity due to poloxamer and chitosan and can prevent dental caries due to nHA and NaF. We propose this formulation as a promising dental material in tooth surface remineralization.

Enamel remineralization potential and antimicrobial effect of a fluoride varnish containing calcium strontium silicate

OBJECTIVES

To investigate enamel remineralization and antimicrobial effect of sodium fluoride (NaF) varnish containing calcium strontium silicate (CSR).

METHODS

CSR was synthesized by sol-gel process and incorporated in 5 % NaF varnish at three different concentrations (1 %, 2 %, and 4 % w/v). The treatment/control groups were: 1 % CSR+NaF, 2 % CSR+NaF, 4 % CSR+NaF, NaF, and no treatment. Strontium and fluoride release from the varnishes was evaluated. Sound enamel specimens (n = 6) were demineralized, varnish-treated, and subjected to remineralization cycle. Mineral density of enamel specimens was evaluated using micro-CT. Antimicrobial effect of the varnishes on Streptococcus mutans and Lactobacillus acidophilus biofilms was assessed using confocal laser scanning microscopy. The HGF-1 cytotoxicity of the varnishes was examined using CCK-8 assay.

RESULTS

Both 2 % and 4 % CSR+NaF varnishes showed significantly higher F release and remineralization potential than NaF varnish (p < 0.05). Dead bacterial proportion of 4 % CSR+NaF varnish was significantly higher than NaF varnish (p < 0.05). The CFUs values of both S. mutans and L. acidophilus were significantly lower in 4 % CSR+NaF group than NaF group (p < 0.05). No significant difference in cell viability was observed among the groups (p > 0.05).

CONCLUSIONS

Incorporation of 4 % CSR in a NaF varnish significantly enhanced its enamel remineralization and antimicrobial potential with no cytotoxic effect.

CLINICAL SIGNIFICANCE

Dental caries is a major public health problem globally. The study highlights the great potential of CSR-doped NaF varnish as a novel anti-caries agent with synergistic remineralizing and antimicrobial properties to combat early enamel caries lesions in the general population.

Chitosan as a biomaterial for the prevention and treatment of dental caries: antibacterial effect, biomimetic mineralization, and drug delivery

Dental caries is a chronic, progressive disease caused by plaque, influenced by multiple factors and can damage the hard tissues of the teeth. In severe cases, it can also lead to the onset and development of other oral diseases, seriously affecting patients' quality of life. The creation of effective biomaterials for the prevention and treatment of dental caries has become one of the relentless goals of many researchers, with a focus on inhibiting the production of cariogenic plaque and retaining beneficial bacteria, guiding and promoting the reconstruction of dental hard tissues, and delaying the progression of existing caries. Chitosan is a natural cationic polymer extracted from the shells of crustaceans and shellfish. Since its discovery, chitosan has shown to have various biological functions such as antibacterial, biomimetic mineralization, drug delivery, etc., making it one of the most promising biopolymers for new caries prevention and materials of prostheses. Therefore, this article provides an overview of the anti-caries applications of chitosan, which mainly covers the basic research on the application of chitosan in caries prevention and treatment since 2010, with a focus on categorizing and summarizing the following characteristics of chitosan as a caries prevention material, including its antibacterial effect, biomimetic mineralization effect and delivery ability of caries prevention drugs and vaccines. It also explores the limitations of current research on chitosan as a caries prevention biomaterial and the difficulties that need to be focused on and overcome in the future to provide theoretical reference for the clinical implementation of chitosan as a caries prevention biomaterial.

In Vitro Biocompatibility of CPP-ACP and Fluoride-containing Desensitizers on Human Gingival Cells

OBJECTIVES

To analyze the biocompatibility of different desensitizers containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride in their composition: MI Varnish (MV), Clinpro White Varnish (3M Oral Care), Profluorid Varnish (VOCO), Duraphat (Colgate) and Embrace Varnish (Pulpdent) on human gingival fibroblast cells (hGF).

METHODS AND MATERIALS

Human gingival fibroblast (hGF) cells were exposed to several desensitizer extracts at different concentrations (0.1%, 1%, and 4% eluates). Then, in vitro biocompatibility was studied by analyzing the IC50 value, cell proliferation (MTT assay and cell cycle), cell migration (wound healing assay), cell morphology and F-actin content (immunocytofluorescence), and induction of apoptosis/necrosis (flow cytometry). Data were analyzed by one-way analysis of variance (ANOVA) followed by Tukey test.

RESULTS

The lowest cell viability and IC50 were observed in all concentrations of Embrace Varnish-treated hGFs (p<0.001), whereas the highest were exhibited by those treated with Clinpro White Varnish. Similar effects were evidenced when induction of apoptosis/necrosis and cell migration assays were assessed. Finally, MI Varnish, Profluorid Varnish, Duraphat, and Embrace Varnish extracts showed lower numbers of attached cells, some of them with an unusual fibroblastic morphology when cultured with 4% concentration of the varnishes, while Clinpro White Varnish exhibited a similar number of cells with an evident actin cytoskeleton compared to the control group.

CONCLUSIONS

The results obtained in this study indicate that hGFs show better in vitro biocompatibility after exposure to Clinpro White Varnish, even at the highest concentration employed, making it the most eligible for topical applications. In contrast, Embrace Varnish exhibited a high cytotoxicity towards hGFs that could potentially delay the healing process and regeneration of the oral mucosa, although more studies are needed to confirm this hypothesis.

Biomineralization induced by chitosan and collagen-based materials with fluoride for dentin coverage: Chemical and morphological analysis

The prevention and treatment of erosive tooth wear are becoming increasingly important due to its increasing prevalence. The use of natural solutions to modify dental surfaces has become an area of research. Organic materials such as chitosan and hydrolyzed collagen may be a promising option to treat dentin. This in vitro study aimed to evaluate the influence of chitosan or hydrolyzed collagen, alone or combined with acidulated phosphate fluoride (APF) gel, on the composition and morphology of dentin after erosion. Bovine dentin samples were prepared (n = 84) and treated with artificial saliva (AS, negative control); APF gel (F, positive control); chitosan solution (Chi); hydrolyzed collagen solution (Col); fluoride/chitosan composition (F_Chi); and fluoride/hydrolyzed collagen composition (F_Col). Erosive cycles (six cycles of immersion in orange juice for 1 min, followed by immersion in AS for 1 hr) were performed. The materials were characterized by their morphology, composition, and particle size distribution. Micro-energy dispersive X-ray fluorescence spectroscopy and scanning electron were used to evaluate the dentin's inorganic chemical composition and morphology. The F_Col and F groups had a reduction in calcium loss by 17 and 26%, respectively (p < .001). Both of these groups still had a covering layer of agglomerates at the dentin surface after the erosive cycles. The fluoridated chitosan or collagen solutions improved the dentin resistance to erosion as a novel hybrid-fluoride-based material approach to provide surface protection from erosion.

The Application of Chitosan Nanostructures in Stomatology

Chitosan (CS) is a natural polymer with a positive charge, a deacetylated derivative of chitin. Chitosan nanostructures (nano-CS) have received increasing interest due to their potential applications and remarkable properties. They offer advantages in stomatology due to their excellent biocompatibility, their antibacterial properties, and their biodegradability. Nano-CSs can be applied as drug carriers for soft tissue diseases, bone tissue engineering and dental hard tissue remineralization; furthermore, they have been used in endodontics due to their antibacterial properties; and, finally, nano-CS can improve the adhesion and mechanical properties of dental-restorative materials due to their physical blend and chemical combinations. In this review, recent developments in the application of nano-CS for stomatology are summarized, with an emphasis on nano-CS’s performance characteristics in different application fields. Moreover, the challenges posed by and the future trends in its application are assessed.

Effect of TiF4/NaF and chitosan solutions on biofilm formation and prevention of dentin demineralization

OBJECTIVE

This study evaluated the effect of experimental solutions containing TiF₄/NaF and chitosan on bacterial species of microcosm biofilm and on dentin demineralization.

DESIGN

Microcosm biofilm was produced from human saliva mixed with McBain medium (0.2% sucrose) on bovine dentin for 5 days, under 5% CO₂ and 37 °C. From the 2nd day to 5th day, the treatments were applied (1×60s/day) as following: (1) NaF (500 ppm F^-, positive control); (2) TiF₄ and NaF (TiF₄: 190 ppm Ti⁴⁺ and 300 ppm F^-; NaF: 190 ppm F^-); (3) similar to 2 plus 0.5% chitosan (Ch 500 mPa.s, 75% deacetylation); (4) phosphate buffer solution (negative control); and (5) 0.5% chitosan (Ch 500 mPa.s, 75% deacetylation). CFU counting was performed for total microorganism, total streptococci, total lactobacilli and mutans streptococci. Dentin demineralization was measured by transverse microradiography-TMR. The data were compared using ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p < 0.05).

RESULTS

No differences were found between the treatments with respect to CFU counting (p > 0.05). Dentin treated with TiF₄/NaF plus chitosan solution presented the lowest demineralization compared to the negative control and pure chitosan solution. On the other hand, this experimental solution did not significantly differ from TiF₄/NaF solution, being both able to significantly reduce mineral loss.

CONCLUSION

TiF₄/NaF plus chitosan solution, at suitable pH to be clinically applicable, had no antimicrobial effect, but it was able to reduce dentin caries development under this model.

Drug Delivery (Nano)Platforms for Oral and Dental Applications: Tissue Regeneration, Infection Control, and Cancer Management

The oral cavity and oropharynx are complex environments that are susceptible to physical, chemical, and microbiological insults. They are also common sites for pathological and cancerous changes. The effectiveness of conventional locally-administered medications against diseases affecting these oral milieus may be compromised by constant salivary flow. For systemically-administered medications, drug resistance and adverse side-effects are issues that need to be resolved. New strategies for drug delivery have been investigated over the last decade to overcome these obstacles. Synthesis of nanoparticle-containing agents that promote healing represents a quantum leap in ensuring safe, efficient drug delivery to the affected tissues. Micro/nanoencapsulants with unique structures and properties function as more favorable drug-release platforms than conventional treatment approaches. The present review provides an overview of newly-developed nanocarriers and discusses their potential applications and limitations in various fields of dentistry and oral medicine.

Do viscosity and wettability of fluoride varnishes affect their fluoride release?

Background

There are several brands of fluoride varnishes in the market, but the dynamics of fluoride release from each one might be different. The purpose of this study was to evaluate in vitro the release of fluorides by fluoride varnishes and to determine the correlation with viscosity and wettability.

Material and Methods

Forty four enamel blocks 5x5 mm were randomly divided into 4 groups (n=11) ((Duraphat®, Clinpro™ White Varnish, Flúor Protector® and control). We applied 30 milligrams of fluoride varnish to each specimen. The specimens were immersed in a Calcium Phosphate solution at a pH= 6.0. We evaluated the release of fluoride, by using a selective fluoride electrode, during 6 weeks. Viscosity was measured using an Oswald Viscosimeter and the wettability was determined by measuring the contact angle between the varnish and the enamel slab. The statistical analysis was performed using Analysis of variance.

Results

Duraphat showed the highest fluoride release from the second weekend beyond (p<0.001) and Clinpro the greatest rate of release. Duraphat release was the steadiest throughout the experiment. Duraphat showed the highest viscosity and the lowest wettability (p<0.001) and Fluor Protector showed the highest wettability (p<0.001). There was a positive correlation between the release of fluoride and the viscosity and a negative correlation between fluoride release and wettability (r>0.7).

Conclusions

Viscosity and wettability influence the release of fluoride from fluoride varnishes.

Key words:Fluorides topical, viscosity, wettability.

Harnessing biomolecules for bioinspired dental biomaterials

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.