Morphological, chemical and structural characterisation of deciduous enamel: SEM, EDS, XRD, FTIR and XPS analysis.

AIM: The purpose of this study was to characterise the enamel surface of sound deciduous teeth in terms of morphology, chemical composition, structure and crystalline phases. MATERIALS AND METHODS: The enamel of 30 human deciduous teeth was examined by: Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Chemical differences between incisors and canines were statistically evaluated using the Mann-Whitney U test (p ≤ 0.05). RESULTS: Three enamel patterns were observed by SEM: 'mostly smooth with some groves', 'abundant microporosities' and 'exposed prisms'. The average Ca/P molar ratios were 1.37 and 1.03 by EDS and XPS, respectively. The crystallite size determined by XRD was 210.82 ± 16.78 Å. The mean ratio between Ca bonded to phosphate and Ca bonded to hydroxyl was approximately 10:1. CONCLUSION: The enamel of sound deciduous teeth showed two main patterns: 'mostly smooth with some groves' and 'abundant microporosities'. 'Exposed prisms' was a secondary pattern. There were slight variations among the Ca/P molar ratios found by EDS and XPS, suggesting differences in the mineral content from the enamel surface to the interior. The crystalline phases found in enamel were hydroxyapatite and carbonate apatite, with major type B than type A carbonate incorporation.

Using self-etch adhesive agents with pit and fissure sealants. In vitro analysis of shear bond strength, adhesive remnant index and enamel etching patterns.

PURPOSE: The aim of this study was to evaluate in vitro, the shear bond strength (SBS) and adhesive remnant index (ARI) of pit and fissure sealants (PFS) after enamel conditioning with different new-generation self-etching (SE) agents; additionally, enamel etching patterns were assessed. METHODS: Healthy unerupted third molars surgically removed for therapeutic reasons (n = 25p/g), were randomly assigned to six groups. Conventional etching (CE) or SE was applied prior to pit and fissure sealants bonding. Enamel conditioned surfaces were evaluated by SEM at × 500, × 1000, and × 2000 magnification to determine etching patterns. Subsequently, 25 PFS blocks (3 × 2 × 1.5 mm) p/g were bonded to enamel surface. Samples were stored in water at 37 °C for 24 h, previous to SBS and ARI test. One-way ANOVA and Tamhane statistic tests were used for SBS; while Mann-Whitney U and Kruskal-Wallis were employed for ARI (p ≤ 0.05). RESULTS: For SBS test, CE_PFS_3M and SE1_PFS_Shofu groups showed the lowest values (8.74 ± 4.02 and 8.75 ± 3.90, respectively). The highest scores were observed in SE_PFS_Kuraray group (13.46 ± 5.83). Significant differences in SBS and ARI assessments were found. All experimental groups showed type 1 etching pattern. CONCLUSION: The etching pattern was less pronounced in self-etching groups, which showed an equal or superior in vitro performance compared to conventional etching agents. The clinical use of self-etching agents could be recommended before pit and fissure sealants application in new dental protocols. The best in vitro performance was observed when both applied materials, self-etching agent and pit and fissure sealant have 10-methacryloyloxydecyl dihydrogen phosphate in their chemical composition.

Dental caries and treatment needs in street children in Toluca, Mexico.

OBJECTIVE: To assess dental caries (deft and DMFT) and treatment needs, in street children from the city of Toluca in Mexico. METHODS: After informed consent from their parents, guardian or legal representative, 310 street children, 0 to 17 years of age, from Toluca in the state of Mexico, were evaluated. Caries and treatment needs were recorded according to 1997 WHO criteria. The oral examination was carried out on site in daylight. RESULTS: For the population from which the sample was derived, the caries prevalence was 94.96%, the mean DMFT was 6.0 +/- 4.6 (5.8 decayed), while deft was 3.5 +/- 3.7 (3.4 decayed). Treatment needs in the deciduous dentition revealed that 43.9% of teeth did not require any treatment, 20% needed fissure sealants, 19% required one surface restoration and 13.19% needed restoration in two or more surfaces. In the permanent dentition, the treatment needs were as follows: 51.2% teeth did not need any treatment, 22.9% needed fissure sealants, 18.4% required one surface restoration and 5.3% needed restoration in two or more surfaces. CONCLUSIONS: These findings illustrate the high prevalence of caries in street children in the city of Toluca. There is an enormous need for dental treatment; sealant applications were the treatment most in need. The data can serve as a platform to implement preventive and restorative dental health programmes that meet the needs of Mexican street children,