A Scanning Electron Microscopic Study of Enamel Surfaces of Incipient Caries

Dynamics of Dental Enamel Surface Remineralization under the Action of Toothpastes with Substituted Hydroxyapatite and Birch Extract

To address tooth enamel demineralization resulting from factors such as acid erosion, abrasion, and chronic illness treatments, it is important to develop effective daily dental care products promoting enamel preservation and surface remineralization. This study focused on formulating four toothpastes, each containing calcined synthetic hydroxyapatite (HAP) in distinct compositions, each at 4%, along with 1.3% birch extract. Substitution elements were introduced within the HAP structure to enhance enamel remineralization. The efficacy of each toothpaste formulation was evaluated for repairing enamel and for establishing the dynamic of the remineralization. This was performed by using an in vitro assessment of artificially demineralized enamel slices. The structural HAP features explored by XRD and enamel surface quality by AFM revealed notable restorative properties of these toothpastes. Topographic images and the self-assembly of HAP nanoparticles into thin films on enamel surfaces showcased the formulations' effectiveness. Surface roughness was evaluated through statistical analysis using one-way ANOVA followed by post-test Bonferroni's multiple comparison test with a p value < 0.05 significance setting. Remarkably, enamel nanostructure normalization was observed within a short 10-day period of toothpaste treatment. Optimal remineralization for all toothpastes was reached after about 30 days of treatment. These toothpastes containing birch extract also have a dual function of mineralizing enamel while simultaneously promoting enamel health and restoration.

Carboxymethyl Chitosan-Fluoride-doped Amorphous Calcium Phosphate: A Novel Remineralizing Gel

Background

There is a need for innovative remineralizing gel formulations based on calcium and phosphates that can slowly release fluoride ions and enhance the formation of fluorapatite crystals that are more resistant to dissolution in an acidic environment.

Aim

The aim of the work was to formulate a remineralizing agent that remineralizes enamel through the release of Ca2+, PO₄³-, and F- ions for a prolonged period of time.

Materials and methods

The gel was based on carboxymethyl chitosan (CMC) as a bioinspired gelling agent and on Fluoride-doped Amorphous Calcium Phosphate (F-ACP) as a remineralizing agent. This gel was tested in vitro on the enamel of extracted premolars after demineralization with methacrylic acid gel.

Results

When compared to the control group and demineralized enamel group, the enamel slabs remineralized with CMC/F-ACP showed a higher calcium phosphate ratio in Energy-Dispersive X-ray (EDX) and better surface morphology under scanning electron microscope (SEM).

Conclusion

Remineralization tests performed on demineralized human permanent teeth proved that CMC/F-ACP gel has excellent efficacy, inducing a complete remineralization of the outermost layers of enamel as well as a full restoration of lost mineral content.

How to cite this article

Nimbeni BS, Nimbeni SB, Divakar DD, et al. Carboxymethyl Chitosan-Fluoride-doped Amorphous Calcium Phosphate: A Novel Remineralizing Gel. Int J Clin Pediatr Dent 2023;16(5):734-739.

Qualitative and quantitative assessment of the potential effect of cigarette smoking on enamel of human smokers' teeth

OBJECTIVE

This study aimed to examine the potential changes in enamel surface of human smokers' teeth.

MATERIALS AND METHODS

Forty extracted permanent, human, noncarious anterior teeth were used in this study. Half of these teeth were obtained from heavy smokers, while the other half of teeth were collected from nonsmokers (control teeth). The teeth were then subjected for scanning electron microscopic examination together with energy dispersive X ray and micro-hardness analysis to evaluate the qualitative and quantitative effect of smoking respectively.

RESULTS

SEM of smokers' teeth showed variable degrees of destruction from small areas of demineralization as holes and pits to destruction and deterioration of the organizational pattern of the rod substance. Moreover, areas of defective remineralization were detected. The microhardness, calcium and phosphorus weight % significantly decreased whereas the Ca/P ratio was significantly increased.

CONCLUSION

Cigarette smoking adversely affected the ultrastructure and mechanical properties of enamel and even hindered the normal remineralization process thus cigarette smoking cessation should be promoted in the dental office daily practices.

In Vitro Comparison of Fluoride, Magnesium, and Calcium Phosphate Materials on Prevention of White Spot Lesions around Orthodontic Brackets

One common negative side effect of orthodontic treatment with fixed appliances is the development of white spot lesions (WSLs) around brackets. This study is aimed at comparing the efficacy of various oral hygiene practices in preventing enamel demineralization around orthodontic brackets under similar in vitro conditions. The study included 90 extracted bovine incisors, which were randomized into six groups: fluoride toothpaste (FT), nonfluoride toothpaste (NFT), fluoride varnish plus fluoride toothpaste (FV+FT), CPP-ACP varnish plus fluoride toothpaste (CPP-ACP+FT), medical minerals gel plus nonfluoride toothpaste (MMG+NFT), and no intervention (control). All groups were subjected to demineralization and remineralization cycles. Visual appraisals were used to evaluate the changes in the enamel surface appearance at the beginning and end of the experiment. The changes in the demineralization degree were evaluated by measuring the Ca⁺² concentration in the demineralization solution at different time points. The majority of teeth in the CPP-ACP+FT group exhibited no shift in appearance, whereas in the other groups, a slight change in enamel translucency was observed. At all the time points, the Ca⁺² concentration in the demineralization solution in the CPP-ACP+FT group was the least among all other groups. At day 5, MMG+NFT's preventive efficacy was significantly higher than FV+FT's, but at days 10, 15, and 19, their efficacy was similar. However, at all the time points, MMG+NFT's efficacy was significantly higher than that of control, whereas FV+FT's efficacy was decreased at days 10, 15, and 19 and was close to the efficacy of control. To fight WSLs, early diagnosis was of great importance and examination of the tooth surface after air-drying for 5 s was recommended.

On the method of revealing enamel structure by acid etching. Aspects of optimization and interpretation

The study aimed at finding an optimal combination of acid concentration and etching time when nitric acid is used as etchant for the study of the finer details of human dental enamel structure. Four hundred 2-3-mm-thick segments of facio-lingually sectioned human third molar crowns were assigned to 20 groups with 20 specimens in each group, each group differing with respect to acid concentration (0.1, 1, 2.5, and 5%) and etching time (15, 30, 45, 90, and 180 s). After etching and preparation, specimens were observed in the scanning electron microscope (SEM). Surface roughness/topography increased with increasing acid concentration and increasing etching time, but not in a linear fashion; generally, prisms tended to go from flat-surfaced to cone-shaped and prism sheaths from fissure-like to wedge-shaped. Intragroup variations and intergroup similarities were considerable. The two major enamel factors determining the etch effect are crystal orientation and prism sheath properties. Other factors, such as distribution of porosities and crystal quality, also contribute probably. Slight to moderate topography is best for observing the finer enamel structure, for example, etching with concentrations in the range 0.1-1% and with etching times in the range 15-90 s, the stronger the acid, the shorter the time. The depth effect of nitric acid is judged to be relatively small. Considerable variations in expression of prism cross-striations were observed. SEM observations of acid-etched enamel in carefully selected planes are a powerful method for the study of enamel structure, bearing in mind the artifactual aspects of the observed surface.

Effects of Fluoride and Calcium Phosphate Materials on Remineralization of Mild and Severe White Spot Lesions

Fixed orthodontic treatments often lead to enamel demineralization and cause white spot lesions (WSLs). The aim of this study was to evaluate the mineralization degree of 2 types of WSLs based on ICDAS index and compare the remineralizing efficacy of 3 oral hygiene practices after 1 month and 3 months. 80 mild demineralized and 80 severe demineralized enamel specimens were randomized into three treatments: fluoride toothpaste (FT), fluoride varnish plus fluoride toothpaste (FV+FT), and CPP-ACP plus fluoride toothpaste (CPP-ACP+FT). Microhardness tester, DIAGNODent Pen 2190, and scanning electron microscope were used to evaluate the changes of mineralization degree. Both qualitative and quantitative indicators suggested that the mild and severe white spot lesions were different in the degree of mineralization. Severe WSLs demineralized much more seriously than mild lesions even after 3 months of treatment. Despite the variation in severity, both lesions had the same variation trend after each measure was applied: FT had weak therapeutic effect, FV + FT and CPP-ACP + FT were effective for remineralization. Their remineralizing efficacy was similar after 1 month, and combined use of CPP-ACP plus F toothpaste was more effective after 3 months. In order to fight WSLs, early diagnosis was of great importance, and examination of the tooth surface after air-dry for 5 seconds was recommended. Also, when WSLs were found, added remineralizing treatments were required.