Location of Streptococcus mutans in the Dentinal Tubules of Open Infected Root Canals

Kouchi, Yasuhide; Ninomiya, Jun; Yasuda, Hideyuki; Fukui, Kiichi; Moriyama, Takafumi; Okamoto, Hitoshi

doi:10.1177/00220345800590120301

Cited by 66 publications

(42 citation statements)

References 19 publications

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“…4). Although the study examining the maximal penetration depth of bacteria in residual infected dentin has not been reported, the depth of S. mutans in the dentinal tubules of open infected root canals was found to reach 1,100 mm [21]. Therefore, the thorough removal of soft dentin is encouraged to decrease the thickness effect on laser irradiation.…”

Section: Discussionmentioning

confidence: 99%

Bactericidal effects of diode laser on Streptococcus mutans after irradiation through different thickness of dentin

et al. 2006

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Background and Objectives: A reliable method to eradicate the bacteria of residual carious dentin has not yet been developed. The aim of this study was to evaluate the antibacterial effect of a diode laser on Streptococcus mutans through different thickness (500, 1,000, and 2,000 mm) of human dentin. The thermal effect of laser irradiation was also investigated. Study Design/Materials and Methods: Dentin specimens were inoculated with 2 ml of S. mutans on one side and irradiated by a diode laser on the other side with a power output ranging from 0.5 to 7 W. The laser tip was swept with the whole irradiation area of 7 mmÂ3 mm at a speed of about 10 mm/second with a total irradiation time of 30 seconds. Cooling with distilled water (30 ml/minute) was applied simultaneously during laser irradiation. After laser irradiation, the bacteria was removed from the dentin surfaces and cultured for 48 hours at 378C anaerobically to assess the colony forming units (CFU) per ml. The morphology of the lased bacteria and the temperature rise during laser irradiation were observed by scanning electron microscope (SEM) and measured by thermocouple, respectively. Results: The results revealed that 7 W of laser power could kill 97.7% of CFU through 500 mm thickness of dentin. However, the bactericidal efficiency was significantly reduced as the dentin thickness was increased. The morphological changes of lased bacteria ranged from less affected such as loss of their wall bands and existence of minicells to more severely degenerated, such as disintegration and fusion of cells with pores on the cell wall. Only the dentin specimens with a thickness of 500 mm exhibited a temperature rise greater than 5.58C after receiving 5 or 7 W of laser irradiation. Conclusions: A diode laser can eliminate the Streptococcus mutans of the residual carious dentin without inducing high pulpal temperature rise when the remaining dentin thickness is greater than 1 mm.

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Section: Discussionmentioning

confidence: 99%

Bactericidal effects of diode laser on Streptococcus mutans after irradiation through different thickness of dentin

et al. 2006

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“…Root canal irrigants have limited capability to penetrate into the dentinal tubules and often fail to completely remove the smear layer and eliminate the intracanal infection 2) . Bacterial colonies lodge in the dentinal tubules to a depth of 1150 µm while irrigating solutions can only penetrate into the dentinal tubules for approximately 100 µm 2,3) . In the past two decades, laser technology has gained the spotlight as an adjunct treatment in endodontics.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System-An <i>in vitro</i> study

Asnaashari

Ebad²,

Shojaeian

2016

LASER THERAPY

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Background and aim:Use of laser technology in endodontics has greatly increased in the recent years due to the introduction of new wavelengths and methods and optimal antimicrobial and smear layer removal properties of lasers. This in vitro study aimed to compare the antibacterial effects of diode lasers of 810 nm and 980 nm wavelength on Enterococcus faecalis (E. faecalis) biofilm in the root canal system. Materials and methods: Fifty single-canal human anterior teeth were cleaned, shaped, sterilized and randomly divided into four groups namely two experimental, one positive and one negative control group. The experimental and positive control groups were inoculated with E. faecalis and incubated for two weeks. The experimental group one (n=20) received 810 nm diode laser irradiation (1.5W) while the experimental group two (n=20) was subjected to 980 nm diode laser irradiation (1.5W). The E. faecalis colony forming units (CFUs) were counted in each root canal before and after laser irradiation. Results: Laser irradiation significantly decreased the bacterial colony count in both experimental groups. The reduction in microbial count was significantly greater in 810 nm laser group compared to 980 nm laser group. Conclusion: Irradiation of both 810 and 980 nm lasers significantly decreased the E. faecalis count in the root canal system; 810 nm laser was more effective in decreasing the intracanal microbial load.

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“…It has been shown that the penetration of toluidine blue and methylene blue in healthy dentin are, respectively, 130 and 190 µm, 26 and this penetration is even smaller in the carious dentin, only 52.6 µm below the surface. 27 Therefore, the altered structure of the carious dentin may not allow adequate penetration of the photosensitizer 28,14 and its interaction with microorganisms such as the ones in the mutans group, which have been observed in dental tubules at depths of 200 µm or more from the dentinal surface. 29 The study of new parameters such as the type and concentration of the dyes may give new perspectives for an antimicrobial effect of PDT.…”

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confidence: 99%

Clinical effect of photodynamic therapy on primary carious dentin after partial caries removal

et al. 2016

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This study was conducted to assess the clinical effect of photodynamic therapy (PDT) in the decontamination of the deep dentin of deciduous molars submitted to partial removal of carious tissue. After cavity preparation, dentin samples were taken from the pulp wall of nineteen deciduous molars before and after PDT application. Remaining dentin was treated with 0.01% methylene blue dye followed by irradiation with an InGaAlP diode laser (λ -660 nm; 40 mW; 120 J/cm 2 ; 120 s). Dentin samples were microbiologically assessed for the enumeration of total microorganisms, Lactobacillus spp. and mutans streptococci. There was no significant difference in the number of colony-forming units (CFU) for any of the microorganisms assessed (p > 0.05). Photodynamic therapy, using 0.01% methylene blue dye at a dosimetry of 120 J/cm 2 would not be a viable clinical alternative to reduce bacterial contamination in deep dentin.

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Location of Streptococcus mutans in the Dentinal Tubules of Open Infected Root Canals

Cited by 66 publications

References 19 publications

Bactericidal effects of diode laser on Streptococcus mutans after irradiation through different thickness of dentin

Bactericidal effects of diode laser on Streptococcus mutans after irradiation through different thickness of dentin

Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System-An <i>in vitro</i> study

Clinical effect of photodynamic therapy on primary carious dentin after partial caries removal

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