Morphological and porosity changes in primary enamel surface after an in vitro demineralization model.

In vitro models are very useful in dentistry, especially to evaluate preventive methods against dental caries. Although they have been used for more than 30 years, specific demineralization models have not been established for primary enamel, which is more prone to demineralization than permanent enamel. This study evaluates porosity changes in primary enamel surface after a demineralization model through a scientifically validated analytical tool. Nine healthy human anterior primary teeth extracted for therapeutic reasons were included in this study, previous informed consent. The samples were randomly assigned to three groups n = 3: G1_2D, G2_4D, and G3_7D. Scanning electron microscopy (SEM) images at ×200 and ×1000 were taken during two stages: before demineralization (BD) and after demineralization (AD). Morphological characterization was observed at ×1000, while porosity (pore count and perimeter) was analyzed by the ImageJ program, using ×200 SEM images previously converted. Several statistical analyses were used to determine differences (p ≤ .05). Morphological characterization AD revealed new pits and cracks on the enamel surface in G1_2D and G2_4D groups. Localized eroded enamel areas were observed in G3_7D. Pore count of enamel surface BD ranged from 64.26 ± 37.62 to 97.93 ± 34.25 and AD ranged from 150.06 ± 64.86 to 256 ± 58.14. AD, G_4D exhibited a decrease in pore perimeter contrary to G_2D and G_7D. Significant differences were observed. Finally, morphological changes were more evident as days of demineralization increased; 7 days of immersion could be employed as an enamel erosive model. The pore count increased after the demineralization model, BD pores perimeter was heterogeneous, and AD varied according to the immersion period. Morphological changes were more evident as days of demineralization increased. Seven days of immersion could be employed as an enamel erosive model. The initial porosity seems to be a determining factor for the final porousness. The pore perimeter of the primary enamel varied according to the immersion period on the demineralization model.

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.

Effect of Er:YAG and Fluoride Varnishes for Preventing Primary Enamel Demineralisation.

PURPOSE: To measure the demineralisation changes on human deciduous enamel produced by pH cycling after preventive treatment with Er:YAG laser irradiation, fluoride varnish application and a combination of the two. MATERIALS AND METHODS: Sixty extracted human anterior primary teeth were assigned to six groups (n = 10). Group C: untreated; group L: Er:YAG laser; group TCP-NaF: Clinpro White (5% sodium fluoride and modified tricalcium phosphate); group CPP-ACP-NaF: MI varnish (5% sodium fluoride with casein phosphopeptide-amorphous and calcium phosphate); group L+TCP-NaF: Er:YAG + 5% sodium fluoride + modified tricalcium phosphate; group L+ CPP-ACP-NaF: Er:YAG + 5% sodium fluoride with casein phosphopeptide-amorphous and calcium phosphate. The samples were subjected to a 10-day pH-cycling regimen to create caries-like lesions, with 8 h in demineralising solution and 16 h in remineralising solution at 37°C. Enamel demineralisation was evaluated by laser fluorescence (DIAGNOdent) before and after pH cycling. The Mann-Whitney U-test and Wilcoxon tests were performed with statistical significance set at p ≤ 0.05. RESULTS: The Wilcoxon test revealed statistically significant differences at baseline and after pH cycling in groups C (p = 0.02), L (p = 0.034) and L+TCP-NaF (p = 0.025) and the lowest percentage of healthy tooth substance compared to the other groups. CONCLUSIONS: The results suggest that the treatment protocols employed in groups TCP-NaF, CPP-ACP-NaF, and L+ CPP-ACP-NaF had similar effects in terms of preventing demineralisation, as reflected in a higher percentage of healthy dental structure maintained. Hence, these treatments are recommended for clinical use as an effective preventive measure.