In situ remineralisation response of different artificial caries-like enamel lesions to home-care and professional fluoride treatments

Development and effect of orodispersible film incorporated with Biosilicate for remineralization of dental enamel subjected to cariogenic and erosive challenge

OBJECTIVES

The objective of this in vitro study was to assess the efficiency of incorporating Biosilicate particles (30 and 50 mg) into an experimental orodispersible film and its efficacy in the remineralization process of bovine dental enamel under cariogenic and erosive challenges.

METHODS

Ninety-nine intact incisors, devoid of cracks or fractures, yielding 198 samples (6 × 6 × 2 mm) via vestibular sectioning using a low-speed diamond disc under water cooling. After flattening the enamel surface with 600, 1200, and 2000 grit sandpaper, the samples were divided into two groups based on the challenges they underwent: cariogenic (0.1 M lactic acid at pH 5.0) or erosive (0.05 M citric acid solution at pH 2.3). Samples from each challenge were further categorized into 11 groups (n = 9) according to the duration of cariogenic (3, 7, and 14 days) or erosive (3, 7, and 10 days) challenge, along with positive control groups (fragments untreated with challenges and treated with different Biosilicate concentrations) and negative controls (fragments treated with artificial saliva for the same periods established for cariogenic and erosive challenges). Treatments with orodispersible films containing Biosilicate (30 and 50 mg) were administered for 2 min per day for 15 days.

RESULTS

The highest remineralizing potential was observed in samples treated with Biosilicate after 14 days of cariogenic challenge, irrespective of the concentration tested. For samples subjected to erosive challenge, erosion time did not affect Biosilicate's remineralizing potential.

CONCLUSION

Biosilicate shows promise in terms of remineralizing potential in enamel subjected to cariogenic challenge due to its ability to form hydroxycarbonapatite in mineralized tissues.

Aesthetic impact of resin infiltration and its mechanical effect on ceramic bonding for white spot lesions

BACKGROUND

Treating white spot lesions (WSLs) with resin infiltration alone may not be sufficient, raising questions about its compatibility with other treatments amid controversial or incomplete data. Therefore, this study aimed to assess the aesthetic feasibility of resin infiltration combined with bleaching, as well as its potential mechanical effect on ceramic bonding to WSLs.

METHODS

One hundred and fifty flat enamel surfaces of bovine incisors were prepared. Ninety specimens were deminerailized and randomly assigned to three groups(n = 30): post-bleaching resin infiltration (Bl-R), pre-bleaching resin infiltration (R-Bl), and only resin infiltration (R). Color, surface roughness and microhardness were assessed in immediate, thermocycling and pigmentation tests. The remaining sixty samples were randomly assigned to three groups (n = 20): control (Ctrl), bonding (Bo), pre-bonding resin infiltration (R-Bo). Shear bonding strength, failure mode, micro-leakage depth and interface morphology were evaluated after ceramic bonding. The Tukey test and analysis of variance (ANOVA) were used for statistical analysis.

RESULTS

For the effect of resin infiltration and bleaching on WSLs, the R-Bl group showed the worst chromic masking ability, with the highest |ΔL|, |Δa|, |Δb|, and ΔE values after treatment. Compared with those in the Bl-R group, the R-Bl and R groups showed significant time-dependent staining, which is possibly attributed to their surface roughness. For the effect of resin infiltration on the adhesive properties of WSLs, resin infiltration reduced the staining penetration depth of WSLs from 2393.54 ± 1118.86 μm to 188.46 ± 89.96 μm (P < 0.05) while reducing WSLs porosity in SEM observation.

CONCLUSIONS

Post-bleaching resin infiltration proved to be advantageous in the aesthetic treatment of WSLs. Resin infiltration did not compromise bonding strength but it did reduce microleakage and enhance marginal sealing. Overall, resin infiltration can effectively enhance the chromatic results of treated WSLs and prevent long-term bonding failure between ceramics and enamel. Based on these findings, the use of post-bleaching resin infiltration is recommended, and resin infiltration before ceramic bonding is deemed viable in clinical practice.

Remineralization, color stability and surface roughness of tooth enamel brushed with activated charcoal-based products

OBJECTIVE

To evaluate the effect of activated charcoal-based (AC) products on color alteration, remineralizing potential and surface roughness of dental enamel.

MATERIALS AND METHODS

Bovine incisors were cut into 6 × 6 × 2 mm fragments. Initial color (EasyShade, Vita) and surface roughness (Surfcorder SE1700, Kosakalab) readings were performed. Fragments were separated into five groups (n = 17) according to the treatment: Control: Fluoride toothpaste (Colgate Total 12, Colgate); Charcoal + NaF: AC toothpaste (ACT) with sodium fluoride (Colgate Natural Extracts, Colgate); Charcoal + MFP + n-HA: ACT with sodium monofluorophosphate and nanohydroxyapatite (Black is White, Curaprox); Charcoal: Fluoride-free ACT (ProActive, Hinode); and Charcoal powder: AC powder. Simulated toothbrushing was performed and final color and surface roughness readings were obtained. Fragments were then polished, and initial microhardness (HMV-2, Shimatzu) readings were done. Samples were artificially demineralized and brushed again. Final microhardness readings were taken. Data were statistically analyzed.

RESULTS

Fluoride-free charcoal presented the lowest surface roughness alteration (p < 0.05). Charcoal powder had the lowest color change (p < 0.05) and negative values for whiteness index for dentistry alteration. All the groups presented values below whiteness acceptability threshold and negative relative microhardness values. Control showed the highest remineralizing potential (p < 0.05).

CONCLUSIONS

ACPs did not produce color alteration different from the fluoride toothpaste, except for Charcoal powder that caused less color change. ACPs caused surface roughness alteration similar to the fluoride toothpaste. ACT with fluoride and AC powder did not have remineralizing potential.

CLINICAL SIGNIFICANCE

Activated charcoal-based products (ACP) promise effective tooth whitening and quick results, without teeth damage. In addition, some ACPs contain fluoride in toothpaste composition and promise rehardening potential. However, ACPs are not as effective as other whitening agents and can alter the surface roughness of the enamel. Even if the ACPs contain fluoride or other remineralizing agents, they might be ineffective.

Factors predicting oral health behaviors among students age 13-15 years in Shushtar city, Iran

BACKGROUND

Tooth decay and other oral health (periodontal) diseases are highly prevalent worldwide and present a significant economic burden. Oral health is particularly important for adolescents, as the World Health Organization has identified tooth decay as one of the most pressing global health issues. This study aims to identify predictors of oral health behaviors among students aged 13-15 years in the city of Shushtar, Iran.

METHODS

The present research is a cross-sectional study that was conducted during the summer of 2022 on 415 adolescents from the first secondary school in Shushtar. Two standard questionnaires were used to collect data, consisting of demographic information and questions related to measuring awareness, attitude, performance, and self-efficacy regarding oral health behaviors among adolescents. The collected data was analyzed using SPSS 22 statistical software through descriptive statistics, Pearson correlation, and regression analysis.

RESULTS

The average scores for awareness, attitude, self-efficacy in brushing teeth, self-efficacy in flossing, self-efficacy in going to the dentist, and adolescents' performance on oral health behaviors are 5.72 ± 2.06, 36.40 ± 6.36, 25.40 ± 7.49, 14.15 ± 6.06, 15.80 ± 5.59, and 14.01 ± 4.02, respectively.

CONCLUSION

Based on the results of this study, it can be concluded that adolescents have low levels of awareness, performance, self-efficacy, and a positive attitude towards oral health. Considering the significance of adolescence as a stage for shaping oral health behaviors and their impact on adulthood, it is recommended to increase awareness among adolescents and improve their health behaviors by conducting educational classes in schools.

Enamel Subsurface Caries-Like Lesions Induced in Human Teeth By Different Solutions: A TMR Analysis

This study assessed the effectiveness of models for developing subsurface caries lesions in vitro and verified mineral changes by transverse microradiography (TMR). Enamel blocks from permanent (n=5) and deciduous teeth (n=5) were submitted to lesion induction by immersion in demineralizing solutions during 96 h, followed by pH cycles of demineralization (de) and remineralization (re) for 10 days. Two de-/re solutions were tested. Demineralizing solution "A" was composed by 2.2 mM CaCl2, 2.2 mM KH2PO4, 0.05 M acetic acid, with pH 4.4 adjusted by 1 M KOH. Demineralizing solution "B" was composed by 2.2 mM CaCl2, 2.2 mM NaH2PO4, 0.05 M acetic acid and 0.25 ppmF, with pH 4.5 adjusted by 1M KOH. Solution "A" produced cavitated lesions in permanent teeth, whereas solution "B" led to subsurface lesions in deciduous teeth. Solution "B" was then tested in enamel blocks from permanent teeth (n=5) and subsurface lesions were obtained, so that solution "B" was employed for both substrates, and the blocks were treated with slurries of a fluoride dentifrice (1450 ppm F, as NaF, n=5) or a fluoride-free dentifrice (n=5). Solution "B" produced subsurface lesions in permanent and primary teeth of an average (±SD) depth of 88.4µm (±14.3) and 89.3µm (±15.8), respectively. TMR analysis demonstrated that lesions treated with fluoride-free dentifrice had significantly greater mineral loss. This study concluded that solution "B" developed subsurface lesions after pH cycling, and that mineral changes were successfully assessed by TMR.

Effectiveness of polyacrylic acid-bioactive glass air abrasion preconditioning with NovaMin remineralization on the microhardness of incipient enamel-like lesion

Background:

Bioactive glass (BAG) remineralization is a promising method for dental hard tissue regeneration. The aim of this study was to evaluate the microhardness of incipient enamel-like lesions with or without preconditioning by air abrasion using polyacrylic acid (PAA)-BAG before application of NovaMin remineralizing agent.

Materials and Methods:

Forty extracted human molars were selected, sectioned mesiodistally obtaining buccal and lingual halves, and embedded in resin molds. Specimens were randomly assigned to four groups (n = 10) according to the remineralization protocol: G1 (control, artificial saliva), G2 (preconditioning), G3 (NovaMin), and G4 (preconditioning and NovaMin). Enamel windows 4 mm × 4 mm were done on the buccal and lingual surfaces. Specimens were immersed in a daily renewed demineralizing solution to create white spot lesions. Remineralizing agents were applied according to the manufacturer's instructions, and specimens were stored in a daily renewed artificial saliva. Microhardness was assessed using Vickers hardness number (VHN) at baseline (positive control), after demineralization (negative control), and after 24-h and 1-month remineralization.

Results:

The preconditioning/NovaMin group after 1 month showed a statistically significant high VHN, with no statistically significant difference between it and the positive control. This was followed by the NovaMin group after 1 month, while the lowest VHN was found in the demineralized group, with no statistically significant difference between it and the preconditioning group, whether after 24 h or 1 month.

Conclusions:

Enamel preconditioning with PAA-BAG air abrasion play a major role in enhancement of remineralization when it is accompanied with NovaMin. Furthermore, an extended period of time had helped to attain more benefits from NovaMin remineralization.

Clinical Significance:

Enamel remineralization with NovaMin after conditioning by bioactive glass air abrasion, provides the patients with a fast and durable treatment of incipient enamel lesions, which would reduce the possibility of future progression of demineralization and caries occurrence.

Remineralisation of enamel with silver diamine fluoride and sodium fluoride

OBJECTIVE

To evaluate the remineralising effect of the adjunctive application of 38% silver diamine fluoride (SDF) solution and 5% sodium fluoride (NaF) varnish on artificial enamel caries lesions.

METHODS

Forty-eight demineralised enamel specimens were allocated into four groups. Group 1 received 38% SDF and 5% NaF; Group 2 received 38% SDF; Group 3 received 5% NaF; and Group 4 received deionized water. After pH cycling, the surface morphology and fluoride content of the specimens were studied via scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS). The lesion depth and crystal characteristics were assessed using micro-computed tomography and X-ray diffraction (XRD) respectively. The crystallization reaction was performed by incubating hydroxyapatite powder with NaF or SDF for 48h. The precipitates were studied via transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).

RESULTS

SEM demonstrated the destruction of the enamel surface in Group 4. EDS revealed that the mean fluoride weight percentage of Groups 1-4 were 1.28±0.15, 1.33±0.19, 1.03±0.09 and 0.87±0.04 respectively. The mean lesion depths of Groups 1-4 were 129±14μm, 131±16μm, 153±10μm and 181±21μm respectively. The addition of NaF to SDF did not reduce the lesion depths (p=0.779). XRD revealed that silver chloride formed as a main product in Groups 1 and 2. Meanwhile, TEM analysis indicated that silver nanoparticles were incorporated into hydroxyapatite crystal in SDF-treated hydroxyapatite. XPS spectra suggested that the chemical state of the silver was metallic.

SIGNIFICANCE

The adjunctive application of SDF and NaF varnish had a similar remineralising effect to that of SDF on enamel caries.

In vitro effect of a resin infiltrant on different artificial caries-like enamel lesions

OBJECTIVES

A resin infiltrant was employed for the treatment of active white spot lesions due to its ability to penetrate into the enamel pores and prevent the progression of the lesion. However, limited information is available about its mechanical effect on different artificial enamel lesions as well as on its resistance to further demineralization. Therefore, this study aimed to evaluate the effects of the Icon® infiltrant on different artificial caries-like enamel lesions and its resistance to new acid challenges.

DESIGN

Artificial lesions were produced in bovine enamel using three different protocols (demineralization/remineralization cycling, DE-RE; 8% methylcellulose gel, MC; and methyl ethyl diphosphonate solution, MHDP; n = 13). The specimens were treated with Icon® and subjected to a new acid challenge using DE-RE cycling. The surface and cross-sectional hardness were evaluated in sound, demineralized, treated and further demineralized enamel areas. Data were statistically analyzed using ANOVA and Tukey's test (p < 0.05).

RESULTS

All of the demineralizing protocols produced subsurface artificial caries lesions. The infiltrant was able to partially recover the surface hardness and prevent further surface hardness loss in enamel previously demineralized using the DE-RE and MHDP protocols. In regard to cross-sectional hardness, no positive effect was found.

CONCLUSIONS

The effect of the infiltrant depends on the type of lesion created in vitro, and its action is limited to the lesion surface.