Differentiation of banding patterns between Streptococcus mutans and Streptococcus sobrinus isolates in rep-PCR using ERIC primer

Streptococcus mutans and Streptococcus sobrinus are considered to be important bacterial species in the initiation of human dental caries. Therefore, the establishment of a reliable genotyping method to distinguish S. mutans from S. sobrinus is of central importance.We assessed the usefulness of repetitive extragenic palindromic polymerase chain reaction (rep-PCR) using ERIC primer banding patterns in differentiating S. mutans and S. sobrinus.Five S. mutans and two S. sobrinus prototype strains and 50 clinical isolates (38 S. mutans serotype c, 4 S. sobrinus serotype d, and 8 S. sobrinus serotype g) were examined. The banding patterns of amplicons generated were compared among the prototype strains and clinical isolates, to find common bands that distinguish S. mutans and S. sobrinus.Multiple banding patterns were seen with all strains tested. The representative strains of S. mutans tested revealed six unique, strong bands at 2,000 bp, 1,700 bp, 1,400 bp, 1,100 bp, 850 bp, and 250 bp, whereas S. sobrinus had seven strong bands at 2,000 bp, 1,800 bp, 1,100 bp, 900 bp, 800 bp, 600 bp, and 550 bp. The band at 1,100 bp was the only band that was observed in both S. mutans and S. sobrinus. Furthermore, most clinical S. mutans isolates revealed identical banding patterns. All S. mutans had amplicons at 1,700 bp, 850 bp, and 250 bp, whereas those of S. sobrinus were at 1,100 bp, 900 bp, and 800 bp.These results indicate that using rep-PCR with the ERIC primers can distinguish between S. mutans and S. sobrinus

Stimulatory Effects of CO2 Laser, Er:YAG Laser and Ga-Al-As Laser on Exposed Dentinal Tubule Orifices

We investigated the effects of lasers irradiation on the exposed dentinal tubule. Human tooth specimens with exposed dentinal tubule orifices were used. Three types of lasers (CO2 laser, Er:YAG laser and Ga-Al-As laser) were employed. The parameters were 1.0 W in continuous-wave mode with an irradiation time of 30 s for the CO2 laser, 30 mJ in continuous-wave mode with an irradiation time of 60 s for the Er:YAG laser, and 1.0 W in continuous-wave mode with an irradiation time of 60 s for the Ga-Al-As laser. A non-irradiated group was used as a control. After laser irradiation, the dentinal surface of each sample was observed using SEM. Afterwards, all samples were immersed in methylene blue dye solution in order to evaluate the penetration of the dye solution and observe the change in dentinal permeability after laser irradiation. SEM observation showed that the control group had numerous exposed dentinal tubule orifices, whereas these orifices were closed in the laser-irradiated groups. There was consistent dye penetration into the pulp chamber in the control group, whereas no dye penetration was evident in the laser-irradiated groups. Therefore, laser appears to be a promising treatment for reducing permeation through exposed dentinal tubules

Stimulatory Effects of CO2 Laser, Er:YAG Laser and Ga-Al-As Laser on Exposed Dentinal Tubule Orifices

We investigated the effects of lasers irradiation on the exposed dentinal tubule. Human tooth specimens with exposed dentinal tubule orifices were used. Three types of lasers (CO2 laser, Er:YAG laser and Ga-Al-As laser) were employed. The parameters were 1.0 W in continuous-wave mode with an irradiation time of 30 s for the CO2 laser, 30 mJ in continuous-wave mode with an irradiation time of 60 s for the Er:YAG laser, and 1.0 W in continuous-wave mode with an irradiation time of 60 s for the Ga-Al-As laser. A non-irradiated group was used as a control. After laser irradiation, the dentinal surface of each sample was observed using SEM. Afterwards, all samples were immersed in methylene blue dye solution in order to evaluate the penetration of the dye solution and observe the change in dentinal permeability after laser irradiation. SEM observation showed that the control group had numerous exposed dentinal tubule orifices, whereas these orifices were closed in the laser-irradiated groups. There was consistent dye penetration into the pulp chamber in the control group, whereas no dye penetration was evident in the laser-irradiated groups. Therefore, laser appears to be a promising treatment for reducing permeation through exposed dentinal tubules