A Comparison of Er:YAG Laser with Photon-Initiated Photoacoustic Streaming, Nd:YAG Laser, and Conventional Irrigation on the Eradication of Root Dentinal Tubule Infection by Enterococcus faecalis Biofilms: A Scanning Electron Microscopy Study.

This study evaluated the antimicrobial efficacy of Er:YAG laser activation with photon-initiated photoacoustic streaming (PIPS), Nd:YAG laser disinfection, and conventional irrigation on Enterococcus faecalis biofilms using scanning electron microscopy (SEM). Biofilms were grown on 110 root halves and divided into the following: Groups 1 and 2 (saline and 1% NaOCl with apical position of PIPS, resp.), Groups 3 and 4 (saline and 1% NaOCl with coronal position of PIPS, resp.), Groups 5 and 6 (Nd:YAG laser after saline and 1% NaOCl irrigation, resp.) and Groups 7, 8, and 9 (conventional irrigation with 1% NaOCl, 6% NaOCl, and saline, resp.). SEM images of the apical, middle, and coronal levels were examined using a scoring system. Score differences between Groups 1 and 2 were insignificant at all levels in the remaining biofilm. Group 4 had significantly greater bacterial elimination than Group 3 at all levels. Differences in Nd:YAG laser irradiation between Groups 5 and 6 were insignificant. Groups 7 and 8 were insignificantly different, except at the middle level. Saline group had a higher percentage of biofilms than the others. In this study, PIPS activation with NaOCl eliminates more E. faecalis biofilms in all root canals regardless of the position of the fiber tip.

The Effect of Diode Laser on Planktonic Enterococcus faecalis in Infected Root Canals in an Ex Vivo Model.

OBJECTIVE: This study examined the bactericidal effect of diode laser irradiation against intracanal Enterococcus faecalis. METHODS AND MATERIALS: m total of 128 extracted single-rooted and single-canal teeth were treated with ProTaper instruments (Dentsply Maillefer, Ballaigues, Switzerland). A total of 120 root canals were inoculated with E. faecalis for 21 days, and the samples were randomly divided into five groups: Group 1 (n = 24) samples were irrigated with only saline solution (positive controls); Group 2 (n = 24) was treated with only 5.25% sodium hypochlorite; Group 3 (n = 24) was irrigated with saline solutions activated by diode laser; Group 4 (n = 24) was treated with 5.25% sodium hypochlorite activated by diode laser; and Group 5 (n = 24) was irrigated with saline solution with methylene blue dye activated by the diode laser Fox (Sweden & Martina, Padova, Italy); additionally, eight teeth were not contaminated and their canals were irrigated with saline solution and used as a negative control. The Uro-Quick system was used to determine the microbial residual charge. The data were analyzed using Pearson's chi-square test (p < 0.001). RESULTS: A statistically significant reduction in bacterial count was observed in Group 2 and Group 4 (p < 0.001). There were no statistically significant differences among the other groups (p > 0.001). CONCLUSIONS: Evidence indicates that the diode laser was not more effective than sodium hypochlorite in reducing free bacteria.

Radiation inactivation of Paenibacillus larvae and sterilization of American Foul Brood (AFB) infected hives using Co-60 gamma rays.

The effectiveness of gamma radiation in inactivating the Philippine isolate of Paenibacillus larvae was investigated. Spores of P. larvae were irradiated at incremental doses (0.1, 0.2, 0.4, 0.8 and 1.6 kGy) of gamma radiation emitted by a 6°Co source. Surviving spores were counted and used to estimate the decimal reduction (D10) value. A dose of 0.2 kGy was sufficient to inactivate 90% of the total recoverable spores from an initial count of 105- 9 × 10³ spores per glass plate. The sterilizing effect of high doses of gamma radiation on the spores of P. larvae in infected hives was determined. In this study, a minimum dose (D(min)) of 15 kGy was tested. Beehives with sub-clinical infections of AFB were irradiated and examined for sterility. All the materials were found to be free of P. larvae indicating its susceptibility to γ-rays. After irradiation, there were no visible changes in the physical appearance of the hives' body, wax and frames. Thus, a dose of 15 kGy is effective enough for sterilization of AFB-infected materials.

Bactericidal effect of Nd:YAG and Er:YAG lasers in experimentally infected curved root canals.

OBJECTIVE: The purpose of this study was to evaluate the bactericidal efficacy of Nd:YAG and Er:YAG laser in the experimentally infected curved root canals. BACKGROUND DATA: Previous studies revealed that laser systems have a significant bactericidal effect in both human and bovine infected straight root canals. MATERIALS AND METHODS: Sixty extracted single-rooted teeth with single root canals were selected and then instrumented with endodontic files to a size 60 (K-type file). The degree of root curvature was determined according to modified Schneider's method. Each of the specimens was incubated in a sterile centrifuge tube with 1 mL of the Enterococcus faecalis suspension at 37°C for 2 weeks under aerobic conditions. After laser irradiation at each of the two settings, 50 mJ, 10 pps (0.5 W) or 100 mJ, 10 pps (1.0 W), the number of E. faecalis in each root canal was examined. RESULTS: In the straight root canals, the Er:YAG laser showed higher bactericidal effects by 6.4-10.8% than did the Nd:YAG laser. Conversely, the bactericidal effect of Er:YAG laser in the curved root canals was higher by 1.5-3.1% than was that with the Nd:YAG laser. The bactericidal effect of the Er:YAG laser in the curved root canal is significantly lower than that in the straight root canal (p < 0.05). CONCLUSION: These results suggest that further development in the endodontic laser tip and technique is required to ensure its success in curved root canals sterilization.

Bactericidal activity of erbium, chromium:yttrium-scandium-gallium-garnet laser in root canals.

The aim of this study was to investigate the effectiveness of the erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser by measuring its bactericidal effect inside root canals experimentally colonized with Enterococcus faecalis. We also determined the optimal conditions for the Er,Cr:YSGG laser to achieve the maximal bactericidal effect. An Er,Cr:YSGG Waterlase laser was used, and its antimicrobial effect was compared with that of sodium hypochlorite (NaOCl) at various concentrations as widely used in clinics. This laser emits photons at a wavelength of 2.78 microm. It is a pulsed laser operating at 20 Hz (20 pulses/s). Significant differences between measurements in the different groups (P < 0.05) were observed, depending on time and power used. The use of NaOCl 5% was the most effective procedure, with NaOCl 0.5% being the least effective; however, laser treatment was as effective as NaOCl 5% when applied at 2 W for 60 s.

The role of pulsed light and heat energy (LHE) in acne clearance.

BACKGROUND: Propionibacterium acnes synthesize and store a large amount of porphyrins. Once the porphyrin is exposed to visible light it becomes chemically active and transfers to an excited state, resulting in the formation of singlet oxygen, which combines with cell membranes to destroy the P. acnes. This process is dependent on the rate of production of excited porphyrin molecules, which is influenced by the concentration of porphyrins, the concentration of photons, the temperature, and the wavelength of the photons. METHODS: Nineteen patients with mild to moderate acne underwent bi-weekly treatments for 4 weeks using the ClearTouch system. During each treatment, pulses of light and heat were applied. Each pulse used an average energy density of 3.5 J/cm(2), a pulse width of 35 ms, and a wavelength between 430 and 1100 nm. RESULTS: At the end of the eighth treatment, acne clearance for the non-inflammatory and inflammatory lesions was 63 +/- 21% and 50 +/- 32%, respectively. One month after the last treatment, the acne clearance for non-inflammatory and inflammatory lesions was 79 +/- 22% and 74 +/- 20%, respectively, with further improvement in acne clearance at 2 months after the last treatment (85 +/- 17% and 87 +/- 25%, respectively). CONCLUSION: ClearTouch pulsed light and heat energy (LHE) technology is effective and safe for the treatment of acne vulgaris.