ABSTRACT
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.
Subject(s)
Animals , Cattle , Streptococcus mutans/radiation effects , Bacterial Adhesion/radiation effects , Lasers, Solid-State , Streptococcus mutans/isolation & purification , Streptococcus mutans/physiology , Surface Properties , In Vitro Techniques , Colony Count, Microbial , Dental Enamel/radiation effectsABSTRACT
The aim of this study was to examine Streptococcus mutans biofilm growth on both aged and non-aged restorative dental resins, which were submitted to therapeutic irradiation. Sixty-four disks of an esthetic restorative material (Filtek Supreme) were divided into 2 groups: aged group (AG) and a non-aged group (NAG). Each group was subdivided into 4 subgroups: non-irradiated and irradiated with 10Gy, 35Gy, and 70Gy. The biofilms were produced by Streptococcus mutans UA159 growing on both AG and NAG surfaces. The colony-forming units per mL (CFU/mL) were evaluated by the ANOVA and the Tukey LSD tests (α=0.05). AG presented smaller amounts of CFU/mL than the NAG before irradiation and after 10Gy of irradiation (p<0.05). AG irradiated with 35 and 70Gy showed increased amount of bacterial biofilm when compared to non-irradiated and 10Gy-irradiated disks (p<0.05). The exposure to ionizing radiation at therapeutic doses promoted changes in bacterial adherence of aged dental restorative material.
O objetivo deste estudo foi avaliar a formação do biofilme de Streptococcus mutans crescido em resina restauradora envelhecida e não-envelhecida, submetidas à radiação terapêutica. Sessenta e quatro discos do material restaurador Filtek Supreme foram divididos em 2 grupos: grupo envelhecido (AG) e grupo não-envelhecido (NAG) e cada grupo foi dividido em 4 sub-grupos: não-irradiado e irradiado com 10Gy, 35Gy e 70Gy. O biofilme de S. mutans UA159 foi produzido na superfície de ambos os discos AG e NAG. As unidades formadoras de colônia/mL (UFC/mL) foram avaliadas por ANOVA e teste de Tukey (α=0,05). O grupo AG demonstrou menores quantidades de UFC/mL que o grupo NAG antes da radiação e após a radiação de 10Gy (p<0,05). Os sub-grupos AG irradiados com 35 e 70Gy demonstraram aumento na quantidade de biofilme quando comparado aos não irradiados e irradiados com 10Gy (p<0,05). A exposição à radiação ionizante nas doses terapêuticas promoveu mudanças na aderência bacteriana no material restaurador.
Subject(s)
Bacterial Adhesion/radiation effects , Composite Resins/radiation effects , Dental Pellicle/radiation effects , Radiotherapy , Streptococcus mutans/radiation effects , Analysis of Variance , Biofilms/radiation effects , Dose-Response Relationship, Radiation , Dental Materials/radiation effects , Dental Pellicle/microbiology , Dental Restoration, Permanent/methods , Light-Curing of Dental Adhesives , Statistics, Nonparametric , Time FactorsABSTRACT
Efficiency of ultraviolet (UV) radiation in reducing the cell number of Staphylococcus aureus ATCC 25923 and Escherichia coli K-12 adhered to low-density polyethylene (LDPE) films was evaluated. The microorganisms were let to adhere to the surface of LPDE bags for 12h at 18liC, and then submitted to UV radiation at an intensity 196 icW.cm-2, 254nm, for 2 seconds. Staphylococcus aureus was less resistant to UV radiation than E. coli, and the efficiency increased with the increase of the concentration of microbial suspension. After 1500 hours of use the UV radiation intensity of the lamp was reduced from 288 to 78 icW.cm-2, and the higher decrease occurred in the first 100 hours of use. Also, the efficiency of the UV radiation decreased after 1500 hours of use. The number of mesophilic aerobes on the surface of LDPE films was reduced by 90 percent after irradiation with 137 icW.cm-2 for 2 seconds. Atomic force microscopy revealed cracks and crevices and protuberances on the LDPE surface, a topography that can protect the cells from UV radiation, reducing the efficiency of the process. The results showed that UV radiation can be a useful technique for reducing the microbiota adhered to LDPE films.