Influence of photobiomodulation therapy on root development of rat molars with open apex and pulp necrosis.

This study aimed to evaluate the role of photobiomodulation (PBM) in apexification and apexogenesis of necrotic rat molars with an open apex. Rat molars were exposed to the oral environment for 3 weeks. Canals were rinsed with 2.5% NaOCl and 17% EDTA, filled with antibiotic paste and sealed. After 7 days, canals were rinsed and divided into six groups (n=6): mineral trioxide aggregate (MTA); blood clot (BC); human dental pulp stem cells (hDPSC); MTA+PBM; BC+PBM; and hDPSC+PBM. In hDPSC groups, a 1% agarose gel scaffold was used. Two groups were not exposed: healthy tooth+PBM (n = 6), healthy tooth (n = 3); and one was exposed throughout the experiment: necrotic tooth (n = 3). In PBM groups, irradiation was performed with aluminum gallium indium phosphide (InGaAlP) diode laser for 30 days within 24-h intervals. After that, the specimens were processed for histological and immunohistochemical analyses. Necrotic tooth showed greater neutrophil infiltrate (p < 0.05). Necrotic tooth, healthy tooth, and healthy tooth+PBM groups showed absence of a thin layer of fibrous condensation in the periapical area. All the other groups stimulated the formation of a thicker layer of fibers (p < 0.05). All groups formed more mineralized tissue than necrotic tooth (p < 0.05). PBM associated with MTA, BC, or hDPSC formed more mineralized tissue (p < 0.05). MTA+PBM induced apexification (p < 0.05). Rabbit polyclonal anti-bone sialoprotein (BSP) antibody confirmed the histological findings of mineralized tissue formation, and hDPSC groups exhibited higher percentage of BSP-positive cells. It can be concluded that PBM improved apexification and favored apexogenesis in necrotic rat molars with an open apex.

Efficacy of low-level laser therapy in pain management after root canal treatment or retreatment: a systematic review.

The aim of this study was to assess the effectiveness of low-level laser therapy (LLLT) for pain management after root canal treatment or retreatment. An electronic search for randomized controlled trials was conducted prior to November 2018, through PubMed, EMBASE, the Cochrane library (CENTRAL), and Web of Science. After filtering, seven articles were included, five related to root canal therapy (RCT) and two related to root canal retreatment (RCR). Six of the included studies presented a moderate risk of bias and a one low risk of bias, based on the Cochrane tool of risk of bias evaluation. The laser treatment included diode laser and indium-gallium-aluminum laser. LLLT was compared with placebo, blank, and ibuprofen treatment. Clinical outcome variables included the prevalence of pain, pain intensity, and need for analgesics after treatment. Three studies showed LLLT could reduce the prevalence of pain significantly after RCT or RCR. Although the effect of LLLT on pain intensity varied at different observation time points and among different studies, most of them found patients had lower pain intensity in the LLLT group. Of the three studies that assessed the need for analgesics after treatment, two studies showed significant benefits. Based on the current evidence, the use of LLLT for pain control in postendodontic therapy may be promising. However, solid conclusions should not be drawn definitely, given that more high-quality randomized controlled trials are required to further evaluate the efficacy of LLLT for pain management after RCT and RCR.

Influence of photobiomodulation therapy on root development of rat molars with open apex and pulp necrosis

Abstract This study aimed to evaluate the role of photobiomodulation (PBM) in apexification and apexogenesis of necrotic rat molars with an open apex. Rat molars were exposed to the oral environment for 3 weeks. Canals were rinsed with 2.5% NaOCl and 17% EDTA, filled with antibiotic paste and sealed. After 7 days, canals were rinsed and divided into six groups (n=6): mineral trioxide aggregate (MTA); blood clot (BC); human dental pulp stem cells (hDPSC); MTA+PBM; BC+PBM; and hDPSC+PBM. In hDPSC groups, a 1% agarose gel scaffold was used. Two groups were not exposed: healthy tooth+PBM (n = 6), healthy tooth (n = 3); and one was exposed throughout the experiment: necrotic tooth (n = 3). In PBM groups, irradiation was performed with aluminum gallium indium phosphide (InGaAlP) diode laser for 30 days within 24-h intervals. After that, the specimens were processed for histological and immunohistochemical analyses. Necrotic tooth showed greater neutrophil infiltrate (p < 0.05). Necrotic tooth, healthy tooth, and healthy tooth+PBM groups showed absence of a thin layer of fibrous condensation in the periapical area. All the other groups stimulated the formation of a thicker layer of fibers (p < 0.05). All groups formed more mineralized tissue than necrotic tooth (p < 0.05). PBM associated with MTA, BC, or hDPSC formed more mineralized tissue (p < 0.05). MTA+PBM induced apexification (p < 0.05). Rabbit polyclonal anti-bone sialoprotein (BSP) antibody confirmed the histological findings of mineralized tissue formation, and hDPSC groups exhibited higher percentage of BSP-positive cells. It can be concluded that PBM improved apexification and favored apexogenesis in necrotic rat molars with an open apex.

Antibacterial and Smear Layer Removal Efficacy of Er:YAG Laser Irradiation by Photon-Induced Photoacoustic Streaming in Primary Molar Root Canals: A Preliminary Study.

OBJECTIVE: The objective of this study was to compare antibacterial and smear layer removal efficacy of the erbium:yttrium-aluminium-garnet (Er:YAG) laser irradiation by photon-induced photoacoustic streaming (PIPS), neodymium:yttrium-aluminium-garnet (Nd:YAG), and diode lasers and conventional irrigation agent in primary molar root canals. BACKGROUND: The selection, application, and activation of the irrigant are important factors affecting the success of the endodontic treatment. MATERIALS AND METHODS: Distal root canals of human primary mandibular molar teeth used for antimicrobial efficacy evaluation were first inoculated with Enterococcus faecalis (n = 25). Smear layer removal efficacy was evaluated on the noninoculated specimens (n = 20). The root canals in the first treatment groups were irrigated with a conventional technique using 5% sodium hypochlorite (NaOCl). In the laser groups, the root canals were irradiated with either Nd:YAG (1064 nm) or diode lasers (940 nm) followed by NaOCl irrigation agent. In the fourth groups, the NaOCl irrigation agent was activated with an Er:YAG laser (2940 nm) by PIPS tip using nonablative settings. Antibacterial efficacy was determined by viable counts of E. faecalis after treatments. The treated root canals were examined by scanning electron microscopy to determine the smear layer removal efficacy of treatments. RESULTS: Statistically significant (p < 0.05) reductions in the number of E. faecalis were achieved in Nd:YAG and diode laser groups and Er:YAG laser by PIPS-activated irrigation groups compared to the NaOCl group. Er:YAG laser by PIPS-activated irrigation resulted in more cleaning of the root canal walls and a higher quantity of open tubules. CONCLUSIONS: These findings suggest that Er:YAG laser by PIPS-activated irrigation can be considered as an effective irrigant agitation technique in pediatric endodontics.

The effect of the KTP laser on smear layer and temperature change: an in vitro study.

The purpose of this study was to evaluate the effects of potassium-titanyl-phosphate (KTP) laser irradiation on smear layer removal and temperature changes of the root surfaces. Two hundred four extracted single-root human premolars were included. The canals were instrumented and divided into two main groups: group A (smear layer examination n:119) and group B (temperature change examination n:85). Each group was divided into subgroups (n:17) according to the different five laser power settings: A1, B1: 1 W-5.33 J/cm2; A2, B2: 1.5 W-7.52 J/cm2; A3, B3: 2 W-10.3 J/cm2; A4, B4: 3 W-15.5 J/cm2, A5, B5: 4 W-20.1 J/cm2, A6: positive control no laser irradiation-irrigated 2 mL for 2 min 2.5% NaOCl + 2 mL distilled water and A7: negative control groups no laser irradiation irrigated 2 mL for 2 min 17% EDTA + 2 mL for 2 min 2.5% NaOCl + 2 mL distilled water. The temperature elevations were measured with an infrared thermographic camera and smear layer examined by scanning electron microscope. According to Kruskal-Wallis and Tukey's tests, in all groups the highest smear scores were in the apical third. In all areas, there were statistically significant differences between negative control group (17% EDTA) and all other groups (p < 0.05). The highest smear scores were determined in 1 W KTP laser and positive control (2.5% NaOCl) groups. Statistically, in all thirds, the differences the 3 W and 4 W KTP laser groups between each other and all other groups were significant (p < 0.05). After the end of the use of the laser, increase in temperature values in all groups were found to be below 10 °C in 20 s.

Effect of Laser Etching on Glass Fiber Posts Cemented with Different Adhesive Systems.

BACKGROUND: Glass fiber-reinforced posts have been preferred frequently because of some physical properties similar to the dentin, chemically bonding to dentin, biocompatibility, and esthetics. OBJECTIVE: This study aimed to evaluate the microleakage and bond strength of glass fiber posts cemented with various adhesive systems on laser-etched root canal walls. METHODS: Roots of 120 human mandibular premolars were divided into two groups for push-out bond strength test and the microleakage test (n = 60). Erbium-doped yttrium-aluminum-garnet (Er:YAG) laser etching of the root canal walls was carried out on half of the specimens in both test groups. The laser-treated and laser-nontreated groups were divided again into three subgroups (n = 10). Glass fiber posts (everStick Post) were luted using three different resin cements: total-etch (Variolink N), self-etch (Panavia F 2.0), and self-adhesive (Rely X Unicem). Three dentin discs were obtained from each root, and the bond strength of the glass fiber posts was measured by push-out tests. The dye penetration method was used to investigate coronal microleakage. In addition, surface treatments and the bonding interfaces were observed using scanning electron microscope. RESULTS: The highest bond strengths were observed for the total-etch and self-adhesive resin cement groups with laser etching (p < 0.05), and the lowest bond strength was obtained for the self-etch resin cement group (p < 0.05). There were no statistically significant differences in terms of microleakage (p > 0.05), except for the self-adhesive resin cement group (p < 0.05). CONCLUSIONS: Er:YAG laser etching enhances the bonding strength of glass fiber posts. In addition, laser etching can reduce microleakage of self-adhesive resin cement.

Erbium:Yttrium Aluminum Garnet Laser-Activated Sodium Hypochlorite Irrigation: A Promising Procedure for Minimally Invasive Endodontics.

OBJECTIVE: This study was to evaluate the potential of Erbium:Yttrium Aluminum Garnet laser-activated sodium hypochlorite irrigation (Er:YAG + NaOCl) for minimally invasive endodontics (MIE). BACKGROUND DATA: Er:YAG laser irradiation can dramatically enhance the penetration of NaOCl, which may be a promising protocol for MIE. METHODS: Extracted human teeth were contaminated with Enterococcus faecalis for 4 weeks. The infected canals were then shaped to different apical terminal working widths (ATWW, 15#/0.04, 20#/0.04, 25#/0.04, 30#/0.04, and 40#/0.04) and treated with either Er:YAG + NaOCl (0.3 W, 20 sec) or NaOCl alone. Then, the ATWW were fixed at 15#/0.04, and the canals were treated with Er:YAG + NaOCl at 0.3 W for 40 and 60 sec, or at 0.5 and 1.0 W for 20 sec. Finally, bacterial reductions were evaluated using the cell count method. RESULTS: Er:YAG + NaOCl showed a higher disinfection efficacy at each ATWW compared with NaOCl alone (p < 0.001). The maximum bacterial reduction was 99.9% for the 40#/Er:YAG + NaOCl group and 93.6% for the 40#/NaOCl group. To achieve similar disinfection efficacy, the Er:YAG + NaOCl group needed a smaller ATWW than the NaOCl group. At a fixed ATWW, increasing the output power of the Er:YAG laser was more effective than increasing the radiation time to improve the disinfection efficacy of Er:YAG + NaOCl. The 15#/Er:YAG + NaOCl group reached the maximum bacterial reduction of 99.2% when the Er:YAG laser was activated at 1.0 W for 20 sec. CONCLUSIONS: The 15#/Er:YAG + NaOCl with the Er:YAG laser irradiation at 1.0 W for 20 sec may be considered a promising procedure for MIE.

Determining the optimal dose of 1940-nm thulium fiber laser for assisting the endodontic treatment.

Insufficient cleaning, the complex anatomy of the root canal system, inaccessible accessory canals, and inadequate penetration of irrigants through dentinal tubules minimizes the success of the conventional endodontic treatment. Laser-assisted endodontic treatment enhances the quality of conventional treatment, but each laser wavelength has its own its own limitations. The optimal parameters for the antibacterial efficiency of a new wavelength, 1940-nm Thulium Fiber Laser, were firstly investigated in this study. This paper comprises of two preliminary analyses and one main experimental study, presents data about thermal effects of 1940-nm laser application on root canal tissue, effective sterilization parameters for bacteria, Enterococcus faecalis, and finally the antibacterial effectiveness of this 1940-nm Thulium Fiber Laser irradiation in single root canal. Based on these results, the optimal parameter range for safe laser-assisted root canal treatment was investigated in the main experiments. Comparing the antibacterial effects of four laser powers on an E. faecalis bacteria culture in vitro in 96-well plates showed that the most effective group was the one irradiated with 1 W of laser power (antibacterial effect corresponding to a log kill of 3). After the optimal laser power was determined, varying irradiation durations (15, 30, and 60 s) were compared in disinfecting E. faecalis. Laser application caused significant reduction in colony-forming unit values (CFU) compared with control samples in the 17% ethylenediaminetetraacetic acid (EDTA) group. The results of bacteria counts showed that 1 W with 30 s of irradiation with a 1940-nm thulium fiber laser was the optimal dose for safely achieving maximal bactericidal effect.

Analysis of Human Tooth Pulp Chamber Temperature After 670 nm Laser Irradiation: In Vitro Study.

OBJECTIVE: One of the limiting factors of employing laser radiation on dental therapies is the potential of causing thermal injuries to pulp tissues. The purpose of this study was to evaluate intra-chamber temperature increase on extracted human teeth exposed to 670 nm wavelength InGaAlP laser diode radiation. MATERIALS AND METHODS: In vitro intra-chamber temperature measurements of 12 standardized human teeth (incisors, canines, premolars, and molars; n = 3) were taken both before and after laser radiation. A type-K thermocouple fast-response thermocouple wire with a 0.5 mm diameter probe was inserted into the tooth pulp chamber (ICEL-Manaus-brand). The laser device Lasotronic-brand InGaAlP laser diode was used to irradiate tooth enamel, perpendicularly to the external surface for 30 sec, with power of levels of 340, 272, 204, 136, and 68 mW. The measurements were taken at three time points: 0, 30 sec, and 3 min after the laser irradiation. Measurements were repeated 24 h after removal and reinsertion of the probe in the pulp chamber. The temperature gradient (ΔT in °C) was calculated (ΔT = final temperature-initial temperature) for each group. Data of ΔT were statistically analyzed by two-way analysis of variance (ANOVA) at the 95% confidence level and compared by Tukey post hoc test (α = 0.05). RESULTS: ANOVA showed statistically significant differences to the interaction of factors (p < 0.05). The highest ΔT values obtained were observed to incisors with 340 mW, 272 mW; 204 mW of power (respectively 4.7°C, 4.2°C, and 3.1°C); and canines presented the lowest ΔT (0.8°C-0.3°C) with no influence of power output. CONCLUSIONS: Since the thermal increase was observed in this study, especially in incisors, attention should be paid to avoid pulpal damage.

Effect of Passive Ultrasonic Activation on Organic Tissue Dissolution from Simulated Grooves in Root Canals Using Sodium Hypochlorite with or without Surfactants and EDTA.

INTRODUCTION: The aim of this study was to evaluate the porcine palatal mucosa dissolution from artificial grooves using a final rinse with sodium hypochlorite (NaOCl) with or without a surfactant or ultrasonic activation (PUI). METHODS: The root canals of 130 human maxillary central incisors were chemomechanically prepared and the teeth split. A standardized longitudinal intracanal groove was created in 1 of the root halves. One hundred thirty porcine palatal mucosa samples were collected, adapted in order to fit into the grooves, and weighed. The reassembled specimens were randomly divided in 3 experimental groups (n = 40) based on their irrigation protocol (ie, positive pressure [PP] and PUI during 15 [PUI-15] or 30 seconds [PUI-30]) and divided in subgroups according to the NaOCl preparation used: Vista 6% plain (Vista Dental Products, Racine, WI) or Chlor-XTRA (Vista Dental Products) (containing surfactant). An EDTA intermediate rinse was included. Palatal mucosa weights were measured after the assays. The intergroup weight changes were statistically analyzed. RESULTS: Complete dissolution did not occur in any sample. Chlor-XTRA subgroups were associated with increased weight reduction compared with Vista 6% plain subgroups; however, the differences were significant (P < .05) only for PP and PUI-15. PUI-30 increased weight reduction compared with PP for both hypochlorites and PUI-15 using Vista 6% plain (P < .05). PUI-30 with Vista 6% plain performed significantly better than PP with Chlor-XTRA (P < .05). CONCLUSIONS: The addition of a surfactant to NaOCl and/or PUI activation increased palatal mucosa dissolution within artificial grooves in the root canal of incisor teeth. PUI agitation was often able to compensate for the absence of surfactants.

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.

Temperature Development on the External Root Surface During Laser-Assisted Endodontic Treatment Applying a Microchopped Mode of a 980 nm Diode Laser.

OBJECTIVE: The aim of this article was to investigate the temperature increase of the external root surface during laser-assisted endodontic treatment using a diode laser (980 nm) in a microchopped mode. METHODS: Ten freshly extracted, human maxillary incisors with mature apices were collected, prepared to size F4 at working length (ProTaper; Dentsply Maillefer, Ballaigues, Switzerland), mounted to a holder, and irradiated (using spiral movements in coronal direction) with a diode laser (GENTLEray 980 Classic Plus; KaVo, Biberach, Germany) with a 200 µm fiber in four different treatment groups: Group 1 (control group) was irradiated in six cycles of 5-sec irradiation/20-sec pause with 2.5 W in the pulse mode. Groups 2 to 4 were irradiated at six cycles of 5-sec irradiation/20-sec pause in the microchopped mode (Group 2-1.6 W; Group 3-2.0 W; Group 4-2.5 W). The applied mode was 25 ms on/25 ms off. Within the on period, the laser delivered an intermittent sequence of energy complexes and the maximum output was equal to the nominated output of the device (12 W). Canals were kept moist by sterile saline irrigation in between irradiations, and temperature changes were continuously measured using a thermal imaging camera. Recordings were analyzed by a mixed model (analysis of variance [ANOVA] for repeated measurements). RESULTS: The highest mean of temperature rise, 1.94°C ± 1.07°C, was measured in Group 4, followed by Group 3 (1.74°C ± 1.22°C) and Group 2 (1.58°C ± 1.18°C). The lowest increase occurred in Group 1 (1.06°C ± 1.20°C). There was a significant difference (p = 0.041) between the groups. Significant differences were found between Groups 1 and 4 (p = 0.007) and 1 and 2 (p = 0.035). In addition, a marginally significant difference between Groups 1 and 2 (p = 0.052) was noted. There was no significant difference between Groups 2, 3, and 4. Despite the low mean values reported, the highest temperature increase (+5.7°C) was measured in one of the specimens of treatment Group 2 at the middle third. CONCLUSIONS: Under the conditions used and within the limitations of the study, the microchopped diode laser irradiation is a safe possible treatment option in laser-assisted endodontic treatment, concerning the temperature elevation on the external root surface.

Which is the most effective disinfection method in primary root canals: Conventional or newly developed ones?

BACKGROUND: The aim of the study was to evaluate the antimicrobial activity of the-potassium-titanyl-phosphate--the KTP laser and ozone in of primary root canals. MATERIALS AND METHODS: Sixty primary incisor teeth were selected. The specimens were inoculated with 10 mL Enterococcus faecalis (E. faecalis). Groups: The KTP laser (1,5 W); gaseous ozone (150 s); sodium hypochlorite (NaOCl); saline group. Sterile paper points used to sample bacteria from the canals to tubes containing 5 mL of brain heart infusion broth. Then, 10 mL suspension was incubated in culture media for 24 h. Data were analyzed statistically using Kruskal-Wallis and Mann-Whitney U-test. RESULTS: There were statistically significant differences between all groups (P<0.05). Complete sterilization was achieved in the 2.5% NaOCl group. The number of bacteria were significantly reduced in experimental groups in comparison to the saline group. CONCLUSION: The KTP laser and ozone application provided a significant antibacterial effect in primary root canals; however, 2.5% NaOCl was superior.

Photodynamic therapy in root canals contaminated with Enterococcus faecalis using curcumin as photosensitizer.

The aim of the study was to evaluate the photodynamic therapy (PDT) effect on root canals contaminated with Enterococcus faecalis using a light emitting diode (LED) light and a curcumin solution (CUR) as photosensitizer (PS). Eighty root canals from uniradicular human teeth were prepared with Protaper Universal rotary system and contaminated with E. faecalis for 21 days. They were divided as: GIa-PDT (CUR, pre-irradiation for 5 + 5 min of irradiation); GIb-PDT (CUR, pre-irradiation for 5 + 10 min of irradiation); GIIa-(CUR, pre-irradiation for 5 + 5 min without irradiation); GIIb-(CUR pre-irradiation for 5 + 10 min of irradiation); GIIIa-(physiological solution and irradiation for 5 min); and GIIIb-(physiological solution and irradiation for 10 min); positive and negative control groups. Collections from root canals were made at time intervals of 21 days after contamination, immediately after treatment, and 7 days after treatment, and submitted to colony forming units per milliter (CFU mL(-1)) counts. The data were submitted to ANOVA and Tukey multiple comparison tests, at a level of significance of 5 %. In the immediate post-treatment collection, group GIa showed greater bacterial reduction in comparison with GIIa, GIIb, GIIIa, GIIIb, and positive control (P < 0.05). At 7 days post-treatment, GIa showed significant bacterial reduction only in comparison with GIIIa (P < 0.05). Curcumin as sensitizer was effective by 5 min LED irradiation but not by 10 min irradiation PDT using LED light, and curcumin as PS was not effective in eliminating E. faecalis. No difference was observed for periods of irradiation.

Treatment of dentinal hypersensitivity by means of Nd:YAP Laser: a preliminary in vitro study.

OBJECTIVE: The aim of this study is to evaluate the effectiveness of Nd:YAP laser to seal dentinal tubules at different parameters. MATERIAL AND METHODS: 24 caries-free human wisdom impacted molars were used. The crowns were sectioned transversally in order to totally expose the dentin. The smear layer was removed by a 1 min application of EDTA. Each surface was divided into four quadrants, but only three quadrants were irradiated at a different output power setting (irradiation speed: 1 mm/sec; optical fiber diameter: 320 µm; tangential incidence of beam and in noncontact mode). Samples were smeared with a graphite paste prior to laser irradiation. All specimens were sent for SEM analysis. Pulp temperature increases in additional twenty teeth were measured by a thermocouple. RESULTS: Morphological changes in dentin surfaces depend on the value of used energy density. Higher energy densities (2 W-4 W; 200-400 mJ; pulse duration: 100 m sec.; and 10 Hz) induce higher dentin modifications. Our results confirmed that Nd:YAP laser irradiations can lead to total or partial occlusion of dentin tubules without provoking fissures or cracks. Measurements of pulp temperature increases showed that Nd:YAP laser beam can be considered as harmless for pulp vitality for following irradiation conditions: 2 W (200 mJ) to 4 W (400 mJ) with an irradiation speed of 1 mm/sec; fiber diameter: 320 micrometers; 10 Hz; pulse duration: 100 m sec; noncontact mode and in tangential incidence to exposed dentin. The perpendicular incidence of the laser beam on exposed dentin may injure pulp vitality even at low output power of 3 W. CONCLUSIONS: Nd:YAP laser beam was able to seal the dentin tubules without damaging dentinal surfaces and without harming pulp vitality. Nd:YAP laser is effective and may be safely used for future in vivo treatments of dentinal hypersensitivity under certain conditions.

Photodynamic therapy versus ultrasonic irrigation: interaction with endodontic microbial biofilm, an ex vivo study.

INTRODUCTION: Photodynamic therapy was introduced as an adjuvant to conventional chemo-mechanical debridement during endodontic treatment to overcome the persistence of biofilms. The aim of this study was to evaluate the ability of photodynamic therapy (PDT) to disrupt an experimental microbial biofilm inside the root canal in a clinically applicable working time. MATERIALS AND METHODS: Thirty extracted teeth were prepared and then divided in three groups. All samples were infected with an artificially formed biofilm made of Enterococcus faecalis, Streptococcus salivarius, Porphyromonas gingivalis and Prevotella intermedia bacteria. First group was treated with Aseptim Plus® photo-activated (LED) disinfection system, second group by a 650 nm Diode Laser and Toluidine blue as photosensitizer, and the third group, as control group, by ultrasonic irrigation (PUI) using EDTA 17% and NaOCl 2.6% solutions. The working time for all three groups was fixed at 3 min. Presence or absence of biofilm was assessed by aerobic and anaerobic cultures. RESULTS: There was no statistically significant difference between results obtained from groups treated by Aseptim Plus® and Diode Laser (P<0.6267). In cultures of both groups there was a maximal bacterial growth. The group that was treated by ultrasonic irrigation and NaOCl and EDTA solutions had the best results (P<0.0001): there was a statistically significant reduction of bacterial load and destruction of microbial biofilm. CONCLUSION: Under the condition of this study, Photodynamic therapy could not disrupt endodontic artificial microbial biofilm and could not inhibit bacterial growth in a clinically favorable working time.

Effect of 1440-nanometer neodymium:yttrium-aluminum-garnet laser irradiation on pain and neuropeptide reduction: a randomized prospective clinical trial.

INTRODUCTION: The purpose of this study was to investigate the efficacy of a 1440-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser on relieving pain in relation to the levels of inflammatory cytokine and neuropeptides in the root canal exudates of teeth with persistent symptomatic apical periodontitis. METHODS: Forty teeth with persistent symptomatic apical periodontitis were randomly assigned to treatment groups: group L, intracanal irradiation of 1440-nm Nd:YAG laser with a 300-µm-diameter fiberoptic tip in addition to conventional root canal retreatment, and group C, conventional root canal re-treatment. The degrees of both spontaneous pain and the pain on percussion before and after treatment were recorded, and root canal exudate samples were collected to quantify the associated levels of substance P, calcitonin gene-related peptide (CGRP), and matrix metalloproteinase (MMP)-8 by immunoassay. RESULTS: All of the measured parameters were significantly reduced in group L (P < .05), whereas the level of pain on percussion, CGRP, and MMP-8 were significantly reduced in group C (P < .05). The 1440-nm Nd:YAG laser had significantly better effect on the relief of pain on percussion and the reduction of substance P, CGRP, and MMP-8 levels. The visual analog scale scores of perceived pain correlated with pain-related neuropeptides and inflammatory cytokine levels in root canal exudates. CONCLUSIONS: The 1440-nm Nd:YAG laser irradiation via fiberoptic tip to the teeth with persistent apical periodontitis provided promising consequences of pain and inflammation modulation.

The efficiency of root canal disinfection using a diode laser: in vitro study.

AIMS: The aim of this study is to verify the disinfection of diode laser, following chemo-mechanical procedures against Enterococcus fecalis. MATERIALS AND METHODS: Crowns of 30 extracted premolar teeth were sectioned at the cemento- enamel junction. The canals were shaped using step-back technique to K-file #40. The teeth were randomly assigned to three groups and placed into nutrient broth containing bacterial suspension of Enterococcus fecalis. Group A received no laser radiation. Specimens of group B and C were treated with diode laser (Sirona) with energy set at 1.5 and 3 W, respectively. After laser irradiation, the teeth were placed in vials, which contained 2 mL of the nutrient broth. The vials were incubated at 37°C for 24 h. Grown colonies were identified by standard methods. STATISTICAL ANALYSIS USED: Statistical analysis used was the nonparametric Kruskal-Wallis test, with comparison using the Bonferroni methods of means. RESULTS: Higher mean CFU/mL is recorded in Group A (without laser disinfection) followed by Group B (with 1.5 W laser disinfection) and Group C (with 3 W laser disinfection), respectively. The difference in CFU/mL between the three groups is found to be statistically significant ( P < 0.001). CONCLUSIONS: The results of this research show that the 980 nm diode laser can eliminate bacteria that has immigrated into dentin, thus being able to increase the success rate in endodontic therapy.

Er:YAG laser activation of sodium hypochlorite for root canal soft tissue dissolution.

BACKGROUND AND OBJECTIVE: The aim of this in vitro study was to investigate the effect of Er:YAG laser irradiation on the ability of sodium hypochlorite (NaOCl) to dissolve soft tissue during endodontic procedures. MATERIALS AND METHODS: Two acrylic glass plates, each containing a semi-canal, were bolted together to form a complete canal. This geometry permitted one semi-canal to be filled with fine liver sausage of bovine origin dyed by methylene blue and the other with NaOCl (4.00-4.99% available chlorine; Sigma-Aldrich Corporation, St. Louis, MA), which was then activated by Er:YAG laser irradiation (KEY Laser 3; KaVo, Biberach, Germany) using a plain-ended fiber tip and a range of output energy and repetition rate. To achieve relatively low output energy from high input energy, the laser beam was attenuated by placing glass slides in the beam path. The resultant images acquired were analyzed using pixel-based analysis. Samples were statistically analyzed (two-way ANOVA, P < 0.05, univariate, bifactorial; IBM SPSS Statistics 19, SPSS Inc., Chicago, IL). RESULTS: Both output energy and repetition rate significantly influenced the tissue dissolution ability of NaOCl (P < 0.05). CONCLUSION: Within the limitations of this in vitro study, we conclude that laser activation of NaOCl at 200 mW output power leads to effective soft tissue dissolution. This finding can be of use to endodontists pursuing effective soft tissue dissolution from their irrigants.

Temperature changes in the pulpal chamber and the sealing performance of various methods of direct pulp capping of primary teeth.

AIM: To compare changes in pulpal chamber temperature during the visible-light curing of direct pulp capping compounds and various modes of diode laser irradiation without prior placement of a pulp capping compound and the resultant seals. MATERIALS AND METHODS: Pulp exposure holes were made in 100 extracted human primary first molars, which were randomly assigned to ten equal groups. The holes were sealed by (a= Group 1, 2, 3, 4, 5, 6 and 7) different pulp capping compounds which were cured using various types of visible-light curing units or (b=Group 8, 9 and 10) diode laser irradiation without prior application of a pulp capping compound. Pulpal chamber temperatures were recorded during the procedure, and the resultant seals were examined under a scanning electron microscope. RESULTS: Visible-light curing of the pulp capping compounds and diode laser irradiation at a 0.7 W output power can cause non-injurious temperature rises in the pulpal chamber. At higher output powers of the diode laser, the temperature rises are sufficient to cause thermal injury. The seals were complete when pulp capping compounds were used for direct pulp capping, but were incomplete when laser irradiation without prior placement of a pulp capping compound was used for the identical purpose. CONCLUSION: The visible-light curing of pulp capping compounds is not harmful to vital pulp, and provides an effective seal of the pulp exposure hole. Laser irradiation is not an effective sealant, and can cause thermal injury to vital pulp at high output powers.