Bactericidal Effects of 2.94μm and 1.67μm Laser

Abstract

The bactericidal effects of lasers with wavelengths of 1.67 and 2.94m on cariogenic Streptococcus mutans were investigated. Temperature during irradiation was also measured to determine the mechanism underlying the bactericidal effects of the lasers. An aliquot of 2l cell suspension of S. mutans JC-2 strain was placed on anhydrous quartz or dentin plate, covering an area of approximately 5.0 mm in diameter to a depth of approximately 0.1 mm. Cell suspension was then irradiated at a power of 0.8 W (3.1 J/cm 2 ) at a rate of 40 pps for 30 sec. After irradiation, the plate was put into a bottle containing PBS and vigorously voltated. Solution was serially diluted and inoculated on MS agar. After incubation anaerobically for 72 hr, colony forming units on the agar were counted. The experimental group, the number of bacteria decreased significantly compared to the control group under all conditions. No significant differences were observed in effect of wavelength or plate on bactericidal activity. In conclusion, laser irradiation at a wavelength of 1.67m for 30 sec showed a bactericidal effect on S. mutans, suggesting that this wavelength is more useful than 2.94m due to greater tissue penetration.

Influência da quitosana na biomodificação da dentina após remoção seletiva da lesão de cárie utilizando laser de ER:YAG. Análise clínica, da adaptação marginal da réplica da restauração e microbiológica

“…De acordo com Kukidome et al (2010), devido à baixa penetrância do seu comprimento de onda, a energia do laser de Er:YAG é absorvida pela smear layer e pode não ser capaz de atingir os tecidos mais profundos. Portanto, seria benéfica a incorporação de biomateriais à terapia laser para promover a inativação dos microorganismos remanescentes viáveis.…”