RESUMO
OBJECTIVE: This study evaluated the clinical effectiveness of two exposure times of microwave irradiation on the disinfection of complete dentures. METHODS: Biofilm samples were collected from dentures of 30 patients, who were randomly divided into two experimental groups of 15 subjects each: Group 1-patients had their maxillary denture microwaved for 3 min (650W); Group 2-patients had their maxillary denture microwaved for 2 min (650W). Denture biofilm samples were taken with swabs, before (left side surfaces) and after (right side surfaces) microwave irradiation. All microbial material was plated on selective media for Candida spp., Staphylococcus spp., mutans streptococci and a non-selective media. After incubation (48 h/37 degrees C), the number of colony-forming units (cfu/mL) was counted. Microorganisms which grew on selective media were identified using biochemical methods. The data were statistically analyzed by Kruskal-Wallis test, followed by Dunn's post-test (alpha=0.05). RESULTS: Microwave irradiation for 3 min (Group 1) resulted in sterilization of all dentures evaluated. After microwave irradiation for 2 min (Group 2), a significant decrease in Candida spp. (P=0.0062), Staphylococcus spp. (P=0.0178), mutans streptococci (P=0.0047) and non-identified species (P<0.0001) was achieved in comparison with the cfu/mL obtained before irradiation. The colonies grown after 2 min of microwave irradiation were identified as Candida albicans, non-aureus Staphylococci and Streptococcus mutans. CONCLUSION: Microwave irradiation for 3 min may be a potential treatment to prevent cross-contamination.
Assuntos
Prótese Total Superior/microbiologia , Desinfecção/métodos , Controle de Infecções Dentárias/métodos , Micro-Ondas , Idoso , Idoso de 80 Anos ou mais , Biofilmes/efeitos da radiação , Candida albicans/efeitos da radiação , Contagem de Colônia Microbiana , Humanos , Pessoa de Meia-Idade , Staphylococcus/efeitos da radiação , Streptococcus mutans/efeitos da radiação , Fatores de TempoRESUMO
Laguna (L.) Negra and L. Verde are high altitude Andean lakes located at the 4,400 m altitude in the Andean desert (Puna) in the Argentine northwest. Both lakes are exposed to extreme weather conditions but differ in salinity contents (salinity 6.7% for L. Negra and 0.27% for L. Verde). The aim of this work was to isolate ultraviolet B fraction (UV-B) resistant bacteria under UV-stress in order to determine, a possible connection, between resistance to UV-B and tolerance to salinity. DNA damage was determined by measuring CPDs accumulation. Connection among pigmentation production and UV resistance was also studied. Water samples were exposed to artificial UV-B radiation for 24 h. Water aliquots were plated along the exposition on different media, with different salinity and carbon source content (Lake medium (LM) done with the lake water plus agar and LB). CFU were counted and DNA damage accumulation was determined. Isolated bacteria were identified by 16S rDNA sequence. Their salinity tolerance, were measured at 1, 5 and 10% NaCl and their pigment production in both media was determined. In general it was found that UV resistance and pigment production were the optimum in Lake Medium done with lake water which maintained similar salinity. The most resistant bacteria in L. Negra were different strains of Exiguobacterium sp. and, in L. Verde, Staphylococcus sp. and Stenotrophomonas maltophilia. These bacteria showed the production and increase of UV-Vis absorbing compounds under UV stress and in LM. Bacterial communities from both lakes were well adapted to high UV-B exposure under the experimental conditions, and in many cases UV-B even stimulated growth. The idea that resistance to UV-B could be related to adaptation to high salinity is still an open question that has to be answered with future experiments.
Assuntos
Altitude , Bactérias/isolamento & purificação , Bactérias/efeitos da radiação , Água Doce/microbiologia , Cloreto de Sódio , Raios Ultravioleta , Argentina , Bactérias/classificação , Bactérias/genética , Contagem de Colônia Microbiana , Meios de Cultura , Ecossistema , Água Doce/química , Tolerância a Radiação , Análise de Sequência de DNA , Cloreto de Sódio/análise , Cloreto de Sódio/farmacologia , Staphylococcus/genética , Staphylococcus/isolamento & purificação , Staphylococcus/efeitos da radiação , Stenotrophomonas/genética , Stenotrophomonas/isolamento & purificação , Stenotrophomonas/efeitos da radiaçãoRESUMO
Inúmeras áreas da atividade médica e odontológica têm sido beneficiadas pela utilização do raio laser. O objetivo do presente trabalho foi de avaliar ação bactericida do raio laser de bioestimulação em colônias de Streptococcus e Staphylococcus. Os resultados obtidos demonstram a capacidade do raio laser modificar a viabilidade do número de células bacterianas, tanto sobre Streptococcus quanto sobre Staphylococcus. O efeito bactericida do raio laser mostrou-se proporcional ao tempo de irradiação empregado, com resultados mais satisfatórios aos seis e 12 minutos