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The aim of this study was to evaluate the effect of the Er:YAG laser and its association with fluoride (1.23% acidulate phosphate fluoride gel) on the prevention of enamel erosion. Sixty specimens were obtained from bovine enamel (4 × 4 mm), which were ground flat, polished, and randomly divided into five groups according to the preventive treatments: control-fluoride application; L--Er:YAG laser; L+F--laser + fluoride; F+L--fluoride + laser; L/F--laser/fluoride simultaneously. Half of the enamel surface was covered with nail varnish (control area), and the other half was pretreated with one of the preventive strategies to subsequently be submitted to erosive challenge. When the laser was applied, it was irradiated for 10 s with a focal length of 4 mm and 60 mJ/2 Hz. Fluoride gel was applied for 4 min. Each specimen was individually exposed to regular Coca-Cola® for 1 min, four times/day, for 5 days. Wear analysis was performed with a profilometer, and demineralization was assessed with an optical microscope. Data were analyzed using the Kruskal-Wallis test (wear)/Dunn test and ANOVA/Fisher's exact tests. The group L/F was similar to control group. The other groups showed higher wear, which did not present differences among them. In the demineralization assessment, the groups F+L and L/F showed lower demineralization in relation to the other groups. It can be concluded that none preventive method was able to inhibit dental wear. The treatments L/F and F+L showed lower enamel demineralization.

A eficiência dos lasers associado ou não a fluoretos no aumento da resistência ácida e na redução da solubilidade do esmalte dentário tem sido confirmada em diversos estudos. Diversos comprimentos de onda têm sido utilizados com esta finalidade, apresentando bons resultados e representando uma abordagem preventiva simples e não invasiva. Apesar do emprego do laser Nd:YAG ter sua ação preventiva bem conhecida, são escassos os estudos em dentes decíduos, principalmente estudos que estabeleçam parâmetros seguros e eficientes, seja associado ao flúor ou isoladamente. Desta forma, o objetivo do presente estudo foi avaliar a resistência ácida e a permeabilidade do esmalte decíduo. Para tanto, foram selecionados 69 molares decíduos humanos, resultando em 132 corpos-de-prova. As variáveis de resposta quantitativa foram a microdureza longitudinal, profundidade da desmineralização e permeabilidade do esmalte, e as variáveis de resposta qualitativa foram morfologia da superfície, presença de íons flúor e análise dos componentes químicos do esmalte. Foram utilizados 60 fragmentos vestibular/lingual para a análise de resistência ácida e midrodureza (n=10), e após preparados e tratados, estes espécimes foram submetidos ao ciclo de desremineralização para formação de lesão de cárie artificial. Para análise da permeabilidade (48 fragmentos n=8), para a análise de MEV e EDX (18 fragmentos n=3) e para DRX (6 dentes n=1) foi realizado apenas o tratamento da superfície em 6 níveis: C- Controle: sem tratamento; FA: aplicação de gel flúor fosfato acidulado 1,23%; FAL: aplicação de gel flúor fosfato acidulado + Laser Nd:YAG 0,5W/10Hz no modo contato; VF: aplicação de verniz fluoretado 5%; VFL: aplicação de verniz fluoretado 5% + Laser Nd:YAG; L: aplicação do Laser Nd:YAG. Os dados de microdureza (%VM) foram avaliados pelo teste de Kruskal-Wallis e os dados de profundidade da desmineralização (PD) e Permeabilidade (P) foram avaliados pelos testes ANOVA e Fisher′s LSD (α=5% para todos os testes). Observou-se que os grupos FAL e FA apresentaram a menor variação de dureza em relação aos outros grupos; menor extensão de desmineralização foi observada nos grupos FA, FAL, VF, VFL e L e menor permeabilidade foi verificada nos grupos FA, FAL, VF, VFL e L em relação ao grupo controle (C). Na MEV observouse ausência de fissuras, crateras ou qualquer alteração indesejável na superfície. Na EDX observou-se incorporação de flúor em todos os grupos experimentais (FA, FAL, VF, VFL), exceto no grupo laser (L). Nenhum composto novo foi encontrado na análise de DRX após a associação do flúor com o laser. O laser utilizado isoladamente ou associado ao flúor levou a alterações ultra-estruturais na superfície do esmalte, o que pode ter sido responsável pelo aumento da resistência ácida e redução da permeabilidade, indicando que o laser isoladamente ou associado ao flúor, nas condições desta pesquisa, foi capaz de inibir a desmineralização do esmalte dental decíduo. The efficiency of lasers associated or not with fluorides, in increasing the acid resistance and decrease of enamel solubility of dental enamel has been confirmed by several studies. Several wavelengths have been used for such purpose, providing good results and representing a simple and non-invasive preventive approach. Although the preventive action of Nd:YAG laser is well known, studies on primary teeth are scarce, especially those that establish safe and efficient parameters, when the laser is either associated with fluoride or used alone. Therefore, the aim of this study was to evaluate the acid resistance and permeability of primary tooth enamel. Sixty-nine human primary molars were used, providing 132 specimens. The quantitative response variables were enamel longitudinal microhardness, demineralization depth and permeability, while the qualitative response variables were surface morphology, presence of fluoride ions and analysis of the chemical components of enamel. Sixty buccal/lingual fragments were used for analysis of acid resistance and microhardness (n=10). After being prepared and treated, thee specimens were subjected to a des-remineralization cycle for artificial caries lesion formation. For analysis of permeability (48 fragments, n=8), SEM and EDX (18 fragments, n=3) and DRX (6 teeth, n=1), only surface treatment was performed in 6 levels: C- Control: no treatment; APF: application of 1.23% acidulated phosphate fluoride gel; APFL: application of 1.23% acidulated phosphate fluoride gel + Nd:YAG laser 0.5W/10Hz in mode contact; FV: application of 5% fluoride varnish; FVL: application of 5%fluoride varnish + Nd:YAG laser; L: application of Nd:YAG laser. Microhardness data (%VM) were analyzed by the Kruskal-Wallis test and demineralization depth (DD) and permeability (P) were analyzed by ANOVA and Fisher′s LSD test (α=5% for all tests). APFL and APF presented the lowest microhardness variation of all groups; lower extension of demineralization was observed in groups APF, APFL, FV, FVL and L, and lower permeability was observed in groups APF, APFL, FV, FVL and L compared to group C. The SEM analysis revealed absence of fissures, craters or any other undesirable surface alteration. The EDX analysis revealed fluoride incorporation in all experimental groups (APF, APFL, FV, FVL), except for the group L. No new compound was found in the DRX analysis when fluoride was associated with the laser. Laser alone or associated with fluoride produced ultrastructural alterations on enamel surface, which might have caused the increase of acid resistance and decrease of permeability, thus indicating that, under the conditions of this study, the Nd:YAG laser used alone or associated with fluoride was capable of inhibiting the demineralization of primary tooth enamel.

Mucopolysaccharidosis type IIIB (MPS IIIB) is an autosomal recessive disorder caused by deficiency of the lysosomal enzyme a-N-acetylglucosaminidase. Affected subjects present developmental delay, attention deficit disorder, uncontrollable hyperactivity, and aggressive behavior, followed by progressive dementia and death in late adolescence. The purpose of this paper is to report the dental findings and treatment in a child with MPS IIIB. His primary molars and permanent mandibular incisors presented obliterated pulp chambers and root canals, which may be a clinical manifestation of this disorder.

Most studies dealing with the caries preventive action of Nd:YAG laser have been done in permanent teeth and studies on primary teeth are still lacking. The aim of this study was to evaluate in vitro the effect of Nd:YAG laser combined or not with fluoride sources on the acid resistance of primary tooth enamel after artificial caries induction by assessing longitudinal microhardness and demineralization depth. Sixty enamel blocks obtained from the buccal/lingual surface of exfoliated human primary molars were coated with nail polish/wax, leaving only a 9 mm² area exposed on the outer enamel surface, and randomly assigned to 6 groups (n=10) according to the type of treatment: C-control (no treatment); APF: 1.23% acidulated phosphate fluoride gel; FV: 5% fluoride varnish; L: Nd:YAG laser 0.5 W/10 Hz in contact mode; APFL: fluoride gel + laser; FVL: fluoride varnish + laser. After treatment, the specimens were subjected to a des-remineralization cycle for induction of artificial caries lesions. Longitudinal microhardness data (%LMC) were analyzed by the Kruskal-Wallis test and demineralization depth data were analyzed by oneway ANOVA and Fisher’s LSD test (á=0.05). APFL and APF groups presented the lowest percentage of microhardness change (p