Enamel demineralization model in primary teeth: Micro-CT and SEM assessments of artificial incipient lesion.

Many studies have analyzed different tooth demineralization models, which generate artificial incipient lesions; however, most of them are complex, slow, not clear and results could not be employed in both primary and permanent teeth because of chemical content differences among them. This study evaluates a demineralization model on primary enamel, under three incubation periods; quantifying artificial incipient lesions formation, and depth by micro-CT, complementing with SEM for morphological characterization. Sixteen healthy human anterior primary teeth extracted for prolonged retention and orthopedic/orthodontic reasons were included in this study, previous informed consent. The sample was randomly assigned to four groups n = 4: G_Control, G_2D, G_4D, and G_7D. Micro-CT and SEM were performed during two stages: before demineralization (BD) and after demineralization (AD). A t-student test was carried out to determine differences among groups (p ≤ .05). No incipient lesions were observed in control group. Artificial lesion depth was similar among experimental groups; values were from 38.16 ± 05.40 µm to 42.61 ± 04.75 µm. An amount of 14 to 17 artificial incipient lesions were formed per group, the extension and distribution were different for each incubation period. Five erosive lesions were produced in G_7D. All experimental groups were able to form incipient artificial lesions in primary enamel. SEM characterization revealed more pronounced changes on the enamel surface, as the days of immersion in the demineralization solution increased. The 4-day incubation period is the most recommended for the demineralization model, due to the formation of incipient lesions only and its extension, which facilitates their assessment.

The influence of light-curing time on fluoride release, surface topography, and bacterial adhesion in resin-modified glass ionomer cements: AFM and SEM in vitro study.

Reinforced glass ionomer cements have been widely used in pediatric dentistry to prevent dental caries. However, the influence of biomaterial light-curing and its anti-cariogenic effects remain unclear. This study evaluates the influence of the light-curing time on fluoride release, surface topography, and bacterial adhesion in two types of resin-modified glass ionomer cements (RMGICs). One hundred disks were made, and samples were divided into two groups (n = 50 per group), according to each dental material (Vitremer™ and Ketac™ N100), and also divided into different light-cured times (10, 20, 30, 40, and 60 s). They were placed in phosphate-buffered saline solution (PBS) to measure the fluoride release. Subsequently, an independent sample of RMGICs per group was examined using atomic force microscopy (AFM). Four disks per group were incubated in a brain heart infusion (BHI) medium that was inoculated with Streptococcus mutans GS5 to evaluate the bacterial adhesion by 3-4, [5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide cell viability assay (MTT assay). The fluoride release was related to the light-curing time and gradually decreased as the light-curing time increased in both materials. Surface topography in Vitremer™ presents more irregular surfaces than Ketac™ N100. For S. mutans adhesion, the smallest number of cells per milliliter (cell/ml) was found at 40 s for Vitremer™ and at 30 s for Ketac™ N100. Thus, the shorter light-curing times allowed for major fluoride release in both materials. However, the RMGICs showed different patterns of bacterial adhesion according to the brand and light-curing time.

Acid resistance of dental enamel treated with remineralizing agents, Er:YAG laser and combined treatments.

BACKGROUND: It has been reported that lasers can increase resistance to enamel acids, and when it is associated with fluoride, both are reported to work in synergy, achieving a reduction of the solubility of enamel. Currently, other remineralizing agents have been shown to effectively inhibit enamel demineralization. OBJECTIVES: The aim of the study was to evaluate acid resistance in the occlusal surface of permanent teeth, treated with remineralizing agents, erbium-doped yttrium aluminum garnet (Er:YAG) laser and combined treatments. MATERIAL AND METHODS: Eighty samples of enamel were randomly assigned to 8 groups (n = 10): a control group, and groups treated with sodium fluoride (NaF), casein phosphopeptide-amorphous calcium phosphate with NaF (CPP-ACPF), hydroxyapatite-NaF-xylitol (HA-NaF-X), Er:YAG laser (L), L+NaF, L+CPP-ACPF, and L+HA-NaF-X. The samples were placed in an acid solution and the released calcium (Ca) was quantified by atomic absorption spectrometry. RESULTS: In the groups treated with NaF and L+NaF, a lower loss of Ca was observed - 15.27 ±5.17 mg/L and 15.20 ±3.85 mg/L, respectively - compared to the control group, which had the highest Ca loss: 21.93 ±13.24 mg/L. CONCLUSIONS: Although the combination of Er:YAG laser plus NaF and the single application of NaF showed values suggesting superior resistance to demineralization of dental enamel compared to all the other groups in the study, no statistically significant differences were found to support this assertion.

Morphological and chemical changes of deciduous enamel produced by Er:YAG laser, fluoride, and combined treatment.

OBJECTIVE: The purpose of this study was to evaluate in vitro morphological and chemical changes on human deciduous enamel produced by Er:YAG laser irradiation, fluoride application, combined treatment, and acid dissolution. BACKGROUND DATA: Er:YAG laser has been proposed as a potential preventive dental caries strategy. There is scarce information regarding deciduous enamel. METHODS: Eighty enamel samples were assigned to eight groups (n=10): G1, control; G2, G3, and G4, Er:YAG laser irradiation at 7.5, 12.7, and 39.8 J/cm(2), respectively; G5, fluoride application; G6, G7, and G8, irradiation at previous densities plus fluoride application. Morphology was evaluated by scanning electron microscopy, and chemical composition was determined by energy dispersive X-ray spectroscopy before treatment (BT), after treatment (AT), and after acid dissolution (AAD). One way and repeated measures analysis of variance (ANOVA) were used (p≤0.05). RESULTS: Morphology of lased surfaces included craters, exposed prisms, fractures, and melting. No morphological modifications appeared after fluoride application, or AAD. Chemically, AT: C atomic percentage (at%) decreased in G3, G4, and G8; O at% decreased in G5-G8; F content was higher for G7; trace elements remained under 1.0 at%; Ca at % increased in G4, G7, and G8; there were increments in P at% in G4 and G8; and Ca/P increased in G4, G7, and G8. AAD: F at% dropped to 0.00 in G5-G8; and P at% increased in G7. CONCLUSIONS: Morphological changes of Er:YAG irradiated enamel represented mild to severe damages. Conditions employed in this study are not recommended for deciduous caries prevention. Er:YAG energy density influenced chemical changes in enamel to enhance its structure. Acid dissolution removed fluoride from enamel surface.

Evaluation of self-etching adhesive and Er:YAG laser conditioning on the shear bond strength of orthodontic brackets.

The purpose of this study was to evaluate the shear bond strength, the adhesive remnant index scores, and etch surface of teeth prepared for orthodontic bracket bonding with self-etching primer and Er:YAG laser conditioning. One hundred and twenty bovine incisors were randomly divided into four groups. In Group I (Control), the teeth were conditioned with 35% phosphoric acid for 15 seconds. In Group II the teeth were conditioned with Transbond Plus SEP (5 sec); III and IV were irradiated with the Er:YAG 150 mJ (11.0 J/cm²), 150 mJ (19.1 J/cm²), respectively, at 7-12 Hz with water spray. After surface preparation, upper central incisor stainless steel brackets were bonded with Transbond Plus Color Change Adhesive. The teeth were stored in water at 37°C for 24 hours and shear bond strengths were measured, and adhesive remnant index (ARI) was determined. The conditioned surface was observed under a scanning electron microscope. One-way ANOVA and chi-square test were used. Group I showed the significantly highest values of bond strength with a mean value of 8.2 megapascals (MPa). The lesser amount of adhesive remnant was found in Group III. The results of this study suggest that Er:YAG laser irradiation could not be an option for enamel conditioning.

Prevalencia de caries y conocimientos sobre salud-enfermedad bucal de niños 3 a 12 años en el Estado de México / Caries prevalence and knowledges about oral health-disease in 3-12-year-old children of the Mexico State

El propósito del presente trabajo fue determinar la prevalencia de caries y conocimientos de salud-enfermedad bucal en preescolares y escolares; y obtener una línea basal en los de nuevo ingreso. Se examinaron un total de 634 alumnos de 3 a 12 años de dos jardines de niños y cuatro escuelas primarias pertenecientes a los municipios de Toluca y Metepec del Estado de México. La prevalencia de caries se evaluó de acuerdo a los criterios de la OMS. El conocimiento salud-enfermedad bucal se evaluó mediante encuestas que fueron diseñadas por grado escolar y características psicopedagógicas. Los resultados mostraron que el 74 por ciento de los escolares presentaron caries dental en ambas denticiones. El índice cpos fue de 7.5 y CPOS de 0.6. El componente cariado representó 4.7 superficies en promedio en la dentición temporal y 0.5 en la permanente. La superficie que con mayor frecuencia se encontró cariada y obturada fue la oclusal. No se encontraron diferencias estadísticamente significativas entre ambos sexos al aplicar el análisis lineal multivariado. El 58 por ciento de los preescolares y escolares mostraron un nivel de conocimiento bueno. La población requiere de la aplicación de medidas preventivas adicionales y un programa restaurativo.