Laser irradiation prevents root caries: Microhardness and scanning electron microscopy analysis

Context: A promising option for the prevention of dental caries is the use of laser irradiation. Aims: Evaluate the effects of Er:YAG, Nd:YAG, and CO2 laser irradiation, associated or not to 2% sodium fluoride (2% NaF), on root caries prevention. Material and Methods: One hundred and four human root dentin samples were divided in eight groups (n = 13). A 9?mm2?area on each dentin sample was delimited and treated as follows: G1: no treatment (control); G2: 2% NaF; G3: Er:YAG; G4: 2% NaF + Er:YAG; G5: Nd:YAG; G6: 2% NaF + Nd:YAG; G7: CO2; G8: 2% NaF + CO2. When used, the 2% NaF was applied before irradiation for 4 min. The samples were subjected to a 2?week cariogenic challenge, consisted of daily immersion in de?remineralizing solutions for 6 h and 18 h, respectively. Knoop hardness (KHN) were evaluated (10 g and 20 s) at different depths from the dentin surface. The samples (n = 3) were prepared for scanning electron microscopy (SEM). Microhardness data were analysed by one?way analysis of variance (ANOVA) and Fisher’s test (? = 5%). Results: The Er:YAG laser group (KHN = 41.30) promoted an increase in acid resistance of the dentin (P < 0.05) when compared to all groups. There was no synergism between laser irradiation and 2% NaF application. Morphological changes were observed after irradiation with all lasers; carbonization and cracks were also observed, except when Er:YAG were used. Conclusions: Er:YAG laser irradiation can safely increase the acid resistance of the dentin surface of the root, since it promoted a significant increase in surface hardness. The application of 2% NaF did not result in a synergistic effect

Evaluation of Surface Roughness and Bacterial Adhesion on Tooth Enamel Irradiated With High Intensity Lasers

Abstract The aim was to evaluate the surface roughness and bacterial adhesion on enamel irradiated with high intensity lasers, associated or not to a fluoride varnish. Eighty fragments of bovine enamel were equally divided in 8 groups (n=10). Group 1 was not treated and Group 2 received only a 5% fluoride varnish application. The other groups were irradiated with an Er:Cr:YSGG (8.92 J/cm2), an Nd:YAG (84.9 J/cm2) and a diode laser (199.04 J/cm2), associated or not to a 5% fluoride varnish. The surface roughness was measured before and after treatments. Afterward, all samples were incubated in a suspension of S. mutans at 37 °C for 24 h. The colony-forming units (CFU) were counted by a stereoscope and the results were expressed in CFU/mm2. One-way ANOVA and the Tukey´s test compared the roughness data and the Student´s test compared the results obtained in the bacterial adhesion test (a=5%). The results showed that the irradiated samples without varnish presented the same roughness and the same bacterial adhesion that the non-irradiated samples. However, samples irradiated in the presence of fluoride varnish showed higher surface roughness and higher bacterial adhesion than the non-irradiated samples and those irradiated without varnish. Presence of pigments in the varnish increased the lasers’ action on the enamel surface, which produced ablation in this hard tissue and significantly increased its surface roughness. For this reason, the enamel’s susceptibility to bacterial adhesion was higher when the irradiation of the samples was made in presence of fluoride varnish.

Resumo O objetivo foi avaliar a rugosidade superficial e adesão bacteriana no esmalte dental irradiado com lasers de alta intensidade, associados ou não a um verniz fluoretado. Oitenta fragmentos de esmalte foram igualmente divididos em 8 grupos (n= 10). O grupo 1 não recebeu tratamento e o grupo 2 recebeu aplicação de verniz fluoretado a 5%. Os outros grupos foram irradiados com os lasers Er,Cr:YSGG (8,92 J/cm2), Nd:YAG (84,9 J/cm2) e um laser de diodo (199,04 J/cm2), associados ou não ao verniz fluoretado. A rugosidade superficial foi medida antes e após os tratamentos. Depois, todas as amostras foram imersas em suspensão de S. mutans a 37 °C durante 24 h. As unidades formadoras de colônia (UFC) foram contadas utilizando uma lupa estereoscópica, e os resultados foram expressos em UFC/mm2. Os resultados de rugosidade foram analisados por ANOVA e pelo teste de Tukey, e a adesão bacteriana foi analisada pelo teste de Student (a=5%). As amostras irradiadas sem verniz apresentaram a mesma rugosidade superficial e a mesma adesão bacteriana que as amostras não irradiadas. No entanto, as amostras irradiadas na presença do verniz fluoretado apresentaram maior rugosidade superficial e aderência bacteriana do que as amostras não irradiadas e daquelas irradiadas sem o verniz. A presença de pigmentos no verniz aumentou a ação dos lasers na superfície do esmalte, promovendo a ablação do tecido duro e aumentando significativamente a sua rugosidade superficial. Por isso, a adesão bacteriana no esmalte foi maior quando a irradiação foi realizada na presença do verniz fluoretado.

Hipoplasia de esmalte em paciente hebiátrico: relato de caso clínico / Enamel hypoplasia in an adolescent patient: clinical case report

O objetivo deste trabalho foi relatar um caso clínico de hipoplasia de esmalte em paciente hebiátrico, assim como a reabilitação estética dos dentes acometidos. Paciente de 12 anos do sexo masculino procurou a policlínica Getúlio Vargas da Universidade de Uberaba queixando-se de alteração de cor de seus dentes permanentes. Clinicamente, observou-se nos terços médio e incisal dos caninos superiores a presença de manchasamareladas e regiões com perda de estrutura dental, sugerindo lesões de hipoplasia de esmalte. Diante das características das lesões foi proposto o tratamento restaurador dos dentes. As estruturas hipoplásicas nos dentes 13 e 23 foram desgastadas limitando-se à remoção da estrutura dentária afetada. Após o condicionamento ácido e aplicação do sistema adesivo, realizou-se a restauração com resina composta micro-híbrida pela técnicade estratificação da dentina e esmalte, seguido pelo acabamento e polimento das restaurações. O resultado clínico observado mostrou que o tratamento proposto foi capaz de restabelecer a harmonia estética, propiciando significativo impacto positivo à auto-estima do paciente.

The objective of this study was to report a case of enamel hypoplasia in an adolescent patient, as well as the aesthetic rehabilitation of the affected teeth. A 12-year-old male patient came to the Dental Clinic of the University of Uberaba complaining about the discoloration of his permanent teeth. Clinically, it was observed in the middle third of the upper canines the presence of yellow spots and surfaces with small cavities, suggesting lesions of enamel hypoplasia. In face of the characteristics of the lesions, the restorative treatment was proposed. The hypoplastic enamel lesions presented in the upper canines were removed with spherical diamond burs. After etching and application of the adhesive system, a micro-hybrid composite was used to fill the cavities. The polishing was done with silicon burs. The clinical outcomes showed that this treatment was able to restore the color and the shape of the affected teeth, providing significantpositive impact on self-esteem of the patient.