Assessment of multispecies biofilm growth on root canal dentin under different radiation therapy regimens.

OBJECTIVES: To assess the growth of a multispecies biofilm on root canal dentin under different radiotherapy regimens. MATERIALS AND METHODS: Sixty-three human root dentin cylinders were distributed into six groups. In three groups, no biofilm was formed (n = 3): NoRT) non-irradiated dentin; RT55) 55 Gy; and RT70) 70 Gy. In the other three groups (n = 18), a 21-day multispecies biofilm (Enterococcus faecalis, Streptococcus mutans, and Candida albicans) was formed in the canal: NoRT + Bio) non-irradiated + biofilm; RT55 + Bio) 55 Gy + biofilm; and RT70 + Bio) 70 Gy + biofilm. The biofilm was quantified (CFUs/mL). Biofilm microstructure was assessed under SEM. Microbial penetration into dentinal tubules was assessed under CLSM. For the biofilm biomass and dentin microhardness pre- and after biofilm growth assessments, 45 bovine dentin specimens were distributed into three groups (n = 15): NoRT) non-irradiated + biofilm; RT55 + Bio) 55 Gy + biofilm; and RT70 + Bio) 70 Gy + biofilm. RESULTS: Irradiated specimens (70 Gy) had higher quantity of microorganisms than non-irradiated (p = .010). There was gradual increase in biofilm biomass from non-irradiated to 55 Gy and 70 Gy (p < .001). Irradiated specimens had greater reduction in microhardness after biofilm growth. Irradiated dentin led to the growth of a more complex and irregular biofilm. There was microbial penetration into the dentinal tubules, regardless of the radiation regimen. CONCLUSION: Radiotherapy increased the number of microorganisms and biofilm biomass and reduced dentin microhardness. Microbial penetration into dentinal tubules was noticeable. CLINICAL RELEVANCE: Cumulative and potentially irreversible side effects of radiotherapy affect biofilm growth on root dentin. These changes could compromise the success of endodontic treatment in oncological patients undergoing head and neck radiotherapy.

Phase-locked µPIV analysis of flow dynamics in a simulated root canal with different laser-activated irrigations.

PURPOSE: To measure the dynamic characteristics of the flow field in a complex root canal model activated by two laser-activated irrigation (LAI) modalities at different activation energy outputs: photon-induced photoacoustic streaming (PIPS) and microshort pulse (MSP). METHODS: A phase-locked micro-scale Particle Image Velocimetry (µPIV) system was employed to characterise the temporal variations of LAI-induced velocity fields in the root canal following a single laser pulse. The wall shear stress (WSS) in the lateral root canal was subsequently estimated from the phase-averaged velocity fields. RESULTS: Both PIPS and MSP were able to generate the 'breath mode' of the irrigant current under all tested conditions. The transient irrigation flush in the root canal peaked at speeds close to 6 m/s. However, this intense flushing effect persisted for only about 2000 µs (or 3% of a single laser-pulse activation cycle). For MSP, the maximum WSS magnitude was approximately 3.08 Pa at an activation energy of E = 20 mJ/pulse, rising to 9.01 Pa at E = 50 mJ/pulse. In comparison, PIPS elevated the WSS to 10.63 Pa at E = 20 mJ/pulse. CONCLUSION: Elevating the activation energy can boost the peak flushing velocity and the maximum WSS, thereby enhancing irrigation efficiency. Given the same activation energy, PIPS outperforms MSP. Additionally, increasing the activation frequency may be an effective strategy to improve irrigation performance further.

The efficacy of a novel SWEEPS laser-activated irrigation compared to ultrasonic activation in the removal of pulp tissue from an isthmus area in the apical third of the root canal.

This study aimed to evaluate the efficacy of Shock Wave Enhanced Emission Photoacoustic Streaming (SWEEPS) in the removal of remaining pulp tissue from the root canal isthmus area in lower molars and compare it with ultrasonically activated irrigation (UAI) and conventional needle irrigation (NI). Forty-one lower molars with isthmuses between mesial canals were included in the study. The teeth were randomly distributed into experimental groups (n = 12/each) based on the final irrigation protocol (SWEEPS, UAI, or NI) and a control group (C) (n = 5). The traditional access cavity of the mesial part of each tooth was made in all samples. The mesial root canals in the experimental groups were instrumented with a Wave One Gold Primary (25/.07) file using 3% sodium hypochlorite (NaOCl) while the distal canal served as a control for the presence of pulp tissue. No treatment was performed in the C group. Sections from the isthmus region were processed for histopathology to measure the remaining pulp tissue (RPT). The results were analyzed using analysis of variance and the Kruskal-Wallis test (α = 0.05). There were no significant differences in the relative surface area of root canals and isthmus among the groups (p > 0.05). Samples in the SWEEPS group had significantly less RPT than UAI, NI, and C (p = 0.003, 0.014, 0.003, respectively). There were no significant differences between the UAI and NI (p = 0.583). SWEEPS was the most efficient in debridement of the root canal isthmus area. UAI and NI showed similar but lower efficiency.

Efficacy of a novel remotely-generated ultrasonic root canal irrigation system for removing biofilm-mimicking hydrogel from a simulated isthmus model.

AIM: To evaluate the efficacy of a novel ultrasonic irrigation device, remotely-generated irrigation with a non-invasive sound field enhancement (RINSE) system, in removing biofilm-mimicking hydrogel from a simulated isthmus model and compare it with sonically- and ultrasonically-activated irrigation systems. METHODOLOGY: A polycarbonate root canal model containing two standardized root canals (apical diameter of 0.20 mm, 4% taper, 18 mm long with a coronal reservoir) connected by three isthmuses (0.40 mm deep, 2 mm high, 4 mm long) was used as the test model. The isthmuses were filled with a hydroxyapatite powder-containing hydrogel. The canals were filled with irrigant, and the models were randomly assigned to the following activation groups (n = 15): EndoActivator (EA), ultrasonically activated irrigation (UAI), and RINSE system (RS). Syringe irrigation (SI) with a 30G needle served as the control. Standardized images of the isthmuses were taken before and after irrigation, and the amount of hydrogel removed was determined using image analysis software and compared across groups using anova (p < .05). RESULTS: Hydrogel removal was significantly higher with the RS (83.7%) than with UAI, EA, or SI (p ≤ .01). UAI (69.2%) removed significantly more hydrogel than SI and EA (p < .05), while there was no significant difference between SI (24.3%) and EA (25.7%) (p = .978). CONCLUSIONS: RINSE system resulted in the most hydrogel removal, performing better than UAI or EA. The effect of RS was also not reliant on the insert or tip entering the pulp chamber or root canal, making it particularly useful in conservative endodontics.

Impact of photodynamic therapy on the marginal adaptation of Biodentine used as root-end filling material.

BACKGROUND: The marginal adaptation of root-end filling materials and the effective antibacterial control in a surgical site are crucial for the successful outcome of endodontic surgery. OBJECTIVE: This study aimed to evaluate the effect of retrograde application of photodynamic therapy on the marginal adaptation of Biodentine used as a root-end filling material. METHODS: Twenty single-rooted anterior teeth were selected, instrumented and obturated with gutta-percha and AH Plus. The apical 3 mm of the roots were resected and root-end cavities were prepared with an ultrasonic retro-tip. The teeth were randomly divided into two groups (n = 10). In the first group, photodynamic therapy (PDT) was applied in the retrograde cavity prior to the root-end filling. In the second group retro cavity was filled without PDT. All specimens were obturated with Biodentine and afterwards sectioned longitudinally. The gap width at the material-dentin interface was measured using a scanning electron microscope. The results were statistically analyzed. RESULTS: The produced gap width by Biodentine/PDT was 3.85 µm versus 2.68 µm in the Biodentine control group with significant differences in-between. CONCLUSION: Under the conditions of this study, PDT has a negative effect on the marginal adaptation of Biodentine used as root-end filling material.

Effect of different laser types on bonding strength of CAD/CAM-customized zirconia post to root canal dentin: an experimental study.

In clinical dentistry, the strength of bonding zirconia posts to root canal dentinal walls currently needs enhancement, and laser application can be an important contribution owing to its features that accommodate adjustable modifications on dental materials. Herein, the effect of different laser treatments applied to dentin surfaces on the strength of bonding zirconia posts to root canal dentinal walls is evaluated by using the pull-out bond strength test in a laboratory setting. A total of 40 single-rooted permanent mandibular premolar teeth that were freshly extracted were used here. The root canal preparation steps were performed using the crown-down technique. Custom-made zirconia posts were produced using CAD/CAM technology. Prior to the application of resin cement, the internal surfaces of the root canals were irradiated using Nd:YAG, Er:YAG, and KTP lasers. Pull-out tests were performed on each specimen by using a universal testing machine. One-way analysis of variance and Tukey post hoc tests were used to compare the pull-out bond strength data. The bond strengths of the laser-treated specimens were greater than those of the untreated controls (p < 0.05). While the value of the pull-out bond strength after Nd:YAG laser treatment was significantly higher than the values obtained after the applications of the Er:YAG and KTP lasers (p < 0.05), the pull-out bond strength after Er:YAG laser treatment was considerably greater than that after KTP laser treatment (p < 0.05). The bond strength between the root canal dentin and the CAD/CAM custom-made zirconia post was improved upon using all the laser modalities in current laboratory settings, among which, application of the Nd:YAG laser was the most successful.

Debris and Smear Layer Removal in Curved Root Canals Using the Dual Wavelength Er,Cr:YSGG/Diode 940 nm Laser and the XP-Endoshaper and Finisher Technique.

Objective: To validate the capability of the dual wavelength laser (Er,Cr:YSGG and diode 940 nm) and the XP-Endoshaper and finisher in removing the smear layer from curved canals. Methods: Forty curved root canals were prepared using the R25 file of the Reciproc® system. The teeth were randomly divided into five groups: G1: negative control irrigated with distilled water, G2: positive control irrigated with EDTA 17% and a final rinse of NaOCl 3%, G3: XP-Endoshaper and finisher with EDTA 17%, G4: dual wavelength Er,Cr:YSGG (1.25 W, 50 Hz, 50 µs) and diode 940 nm (2 W, 50% DC), and G5: dual wavelength Er,Cr:YSGG (2 W, 20 Hz, 50 µs) and diode 940 nm (2 W, 50% DC). Laser scanning microscope images (1000 × ) were scored with the Hülsmann scoring system. Results: Superior smear layer removal was observed in G5 in comparison with G4, especially in the apical third of the canal. Furthermore, the XP-Endoshaper and finisher exhibited positive results in all parts of the canal. Conclusions: The higher power output of the Er,Cr:YSGG in the dual wavelength laser may be a suitable approach to remove the smear layer from the apical third of curved canals. Moreover, the XP-Endoshaper and finisher with EDTA could expose the dentinal tubules, however, the negative side effects of applying EDTA 17% for longer periods must be taken into consideration. This work is clinically significant as it addresses the main aim of endodontic treatment and provides a suitable method to remove the debris, smear layer, and bacterial remnants from the clinically challenging curved root canals.

Efficacy of Er,Cr:YSGG Laser with Different Output Powers on Removing Smear Layer After Retreatment of Two Different Obturation Techniques.

Objective: This study was designed to evaluate the effects of an Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet (Er,Cr:YSGG) laser on removing the filling residues and smear layer (SL) after retreatment using rotary files. Background: Er,Cr:YSGG laser has been proposed as an additional protocol to improve root canal cleaning and removal of the filling remnants. Methods: Eighty-four mandibular premolars were divided into six groups (n = 14). Groups 1, 2, and 3 were obturated using a cold lateral compaction technique, and groups 4, 5, and 6 were obturated using a thermoplasticized injectable technique. The retreatment procedures were performed in all of the groups using a rotary system before applying Er,Cr:YSGG laser at 1.5 W for groups 2 and 5, and at 3.0 W for groups 3 and 6. Then, the teeth were split longitudinally into two halves and observed under a stereomicroscope and a scanning electron microscope. The SL and residual filling materials were evaluated at the coronal, middle, and apical thirds of the root canal. The data were statistically analyzed using three-way analysis of variance and Tukey tests. Results: The 3.0 W Er,Cr:YSGG laser was significantly more effective in removing SL than the other retreatment procedures in the coronal and middle thirds, but there was no significant difference in the apical third (p > 0.05). However, carbonization was observed in some of the specimens in the 3.0 W laser groups. Conclusions: None of the retreatment procedures completely removed the filling remnants from the root canal. However, the additional use of lasers improved the canal cleaning after retreatment.

Comparison of apical irrigant solution extrusion among conventional and laser-activated endodontic irrigation.

The aim of this study was to determine the amount of extruded endodontic irrigant among needle-syringe irrigation (NSI) and laser-activated irrigation (LAI) regimens. Twenty extracted maxillary central incisors were prepared utilizing GT professional rotary files (size 40, taper 0.06). Irrigation was performed with two 27 G irrigation needles (notched open ended (ON) and single side vented (SV)) each at two different irrigant volumetric flow rates (VFR)-0.05 ml/s (3 ml/min) and 0.10 ml/s (6 ml/min). LAI was performed with Er:YAG (erbium-doped yttrium aluminum garnet) using different fiber types (X-Pulse-14/400 cylindrical tip, Preciso- 14/300 flat cylindrical tip, PIPS- 14/400 quartz tapered tip). The Er:YAG laser with a wavelength of 2940 nm (Lightwalker AT, Fotona, Ljubljana, Slovenia) was used according to the following protocol: 10 mJ per pulse, 15 Hz, pulse duration 50 µs. Irrigation time was 60 s for all protocols. Precision syringe pump (PSP) maintained constant irrigant volumetric flow rate. Apically extruded irrigant was collected and net weighed for each protocol (N = 10). Data were analyzed by t tests and Kruskal-Wallis. All LAI regimens had statistically significant lower irrigant extrusion compared with NSI except for the SV 27 G needle used with 0.05 ml/s VFR when compared with the Preciso fiber tip (p = 0,230). The largest amount of extruded irrigant was with the ON 27 G needle at the 0.10 ml/s VFR, while the smallest was after LAI with PIPS fiber tip. The lower quantity of apically extruded irrigant during LAI (X-Pulse and PIPS) points out a safer endodontic irrigation method compared with conventional irrigations.

Effect of Photodynamic Therapy, Er,Cr:YSGG, and Nd:YAG Laser on the Push-Out Bond Strength of Fiber Post to Root Dentin.

Objective: To evaluate the push-out bond strength and modes of failure of fiber post to root dentin by using photodynamic therapy (PDT), Er,Cr:YSGG, Nd:YAG laser, and conventional cleaning and shaping (CCS). Materials and methods: Eighty anterior teeth were sectioned in a horizontal manner being 2 mm incisal to the cementoenamel junction, and root canal was prepared for post space. After post space was made, fiber posts were placed inside the root canal system. The fiber posts were subjected to PDT, Er,Cr:YSGG laser, Nd:YAG laser, and conventional cleaning and shaping (CSS) with 20 specimens in each group. Cervical and apical sections were obtained from the specimens. For performing the push-out test, the universal testing machine was used. The formula used for calculating the push-out bond strength was σ = N/mm2. Results: PDT group (8.16 ± 2.19 MPa) achieved the highest mean push-out bond strength, whereas Er,Cr:YSGG (7.24 ± 1.27 MPa) reported the lowest value in the specimens. Among the experimental groups, the ANOVA test expressed statistical difference (p = 0.481). In the cervical segments, the mean push-out bond strength was found to be higher in all of the experimental groups. For the cervical segments, the independent t-test results showed higher mean push-out bond strength values than the apical segments in PDT, Er,Cr:YSGG, Nd:YAG, and CSS groups, respectively (p < 0.05). Twenty failures were observed at the interface level between the adhesive and surface of dentin. Seven failures were found at the interface between mixed and the adhesive and post, respectively. Conclusions: Push-out bond strength to root canal dentin was not affected by PDT, Er,Cr:YSGG, and Nd:YAG laser compared with CCS. However, PDT produced the smallest number of failure modes and slightly higher push-out bond strength to root dentin. Laser treatment using PDT and Er,Cr:YSGG appeared to be clinically efficient showing acceptable push-out bond strength of fiber post with less number of failures at different regions of the root dentin.

Er,Cr:YSGG Laser-Activated Irrigation and Passive Ultrasonic Irrigation: Comparison of Two Strategies for Root Canal Disinfection.

Objective: To compare the antibacterial effectiveness of 0.5% sodium hypochlorite (NaOCl) activated by the Er,Cr:YSGG laser-activated irrigation (LAI) and passive ultrasonic irrigation (PUI) against a 10-day-old intracanal Enterococcus faecalis biofilm. Background: LAI and PUI are regarded as alternative methods to release the irrigant in the inner regions of the root canal system achieving enhanced cleaning ability. Nevertheless, little evidence regarding the activation of low concentrations of NaOCl has been reported. Materials and methods: Seventy-two single-rooted teeth were instrumented, inoculated (E. faecalis ATCC 29212), and incubated for 10 days to allow biofilm formation. Specimens were randomly divided into six groups (n = 12 each): (1) 0.5% NaOCl+Er,Cr:YSGG LAI, (2) saline+Er,Cr:YSGG LAI, (3) 0.5% NaOCl+PUI, (4) saline+PUI, (5) positive control (no treatment), and (6) negative control (no bacteria). The activation time was distributed as follows: 30 sec of activation, followed by a rest phase of 30 sec, and ending with 30 sec of activation. The number of bacterial survivors was determined by plate counting. Results: Both irrigation regimens LAI and PUI reduced the number of colony-forming unit. Moreover, LAI +0.5% NaOCl and the rest of groups significantly differ (p < 0.001 for all comparisons). Conclusions: Er,Cr:YSGG LAI proved to be more effective than PUI in enhancing the antimicrobial activity of 0.5% NaOCl against 10-day-old intracanal E. faecalis biofilms.

Antimicrobial efficacy of photodynamic therapy, diode laser, and sodium hypochlorite and their combinations on endodontic pathogens.

BACKGROUND: Sterilization of the root canal system is of prime importance for a successful root canal therapy. Lasers and photodynamic therapy (PDT) have become the latest choice to eradicate microorganisms in the root canal. OBJECTIVE(S): To evaluate and compare the antimicrobial activity of diode laser, photodynamic therapy, and sodium hypochlorite along with their combinations on endodontic pathogens: Enterococcus faecalis and Streptococcus mutans. METHODS: A total of 120 uniradicular teeth were stored in 5.2% NaOCl solution to remove organic residues and the crowns were sectioned at the cemento-enamel junction (CEJ) to obtain root canal length of 15 mm. Canals were shaped using step-back technique up to #40 K-file and were autoclaved. The selected teeth (specimen) were randomly divided into two equal groups with sixty teeth being inoculated with E. faecalis (Group E) and remaining sixty teeth with S. mutans (Group S). Further, the groups were subdivided according to the disinfection technique used. Ten teeth from each subgroup were disinfected with a diode laser, photo activated disinfection (PAD), sodium hypochlorite, a combination of sodium hypochlorite and diode laser, a combination of sodium hypochlorite and photo activated disinfection respectively. Ten teeth in each group served as control without any disinfection. The treated specimens were transferred to test tubes containing 5 ml sterile Luria Bertani broth, incubated and the bacterial count, optical density in each root specimen was calculated and compared. The pairwise comparison of colonies across the subgroups was done by the Kruskal-Wallis test and within the subgroups was carried out using the Mann-Whitney U test. The statistical implication was tested at 5% and the study was performed using SPSS 18.0 ver. (SPSS Inc.). RESULTS: A significant reduction (98%) in the E. faecalis count was observed when the NaOCl was used in combination with the diode laser or PAD. PAD along with 3% NaOCl presents the advantage of utilizing a lower wavelength laser beam. Hence, PAD in combination with NaOCl can be an alternative and better option for root canal disinfection for both the endodontic pathogens, E. faecalis and S. mutans.

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.

Evaluation of Apical Extrusion During Novel Er:YAG Laser-Activated Irrigation Modality.

Objective: To evaluate apical extrusion during a novel erbium-doped yttrium aluminum garnet (Er:YAG) laser-activated irrigation (LAI) modality. Background data: A novel double-pulse Er:YAG modality (AutoSWEEPS) was introduced recently, replacing a single laser pulse with two micropulses that are separated by a varying time delay (which is continuously "swept" between 300 and 600 µsec). Although the proposed method demonstrated increased efficacy, no data were yet available on extrusion. Methods: The extrusion was evaluated on simulated canals (n = 6) using particle imaging velocimetry. In the first two groups, the irrigation device was a syringe coupled to either a 30-G open-ended or side-vented needle, with flow rates of 1, 2, 5, and 15 mL/min. In the second two groups, irrigant activation was performed with an Er:YAG laser, using either a super-short pulse (SSP) or AutoSWEEPS modality. The pulse energies were 5, 10, 20, 30, and 40 mJ and the frequency was 10 Hz. Results: The measured extrusion was most prominent during the open-ended needle irrigation, followed by the vented needle irrigation. Compared with the conventional needle irrigation (CNI), all the studied LAI modalities resulted in ∼3-20 times less extrusion. The AutoSWEEPS modality induced the smallest extrusion rate, which was always <1.5 mm3/sec and was also independent of the laser energy. Conclusions: Within the limitations of the study, our results demonstrate that the SSP and AutoSWEEPS laser-assisted irrigation methods exhibited less extrusion in comparison with CNI methods.

Effect of ultrasonic and Nd: Yag laser activation on irrigants on the push-out bond strength of fiber post to the root canal.

OBJECTIVE: This in vitro study aimed to compare the efficacy of irrigants using various irrigation activation methods to the push-out bond strengths of fiber post to root canal luted with self-adhesive resin cement (SARC). METHODOLOGY: Forty-eight decoronated human canines were used. The specimens were divided into four groups corresponding with the post-space irrigation process and were treated as follows: distilled water (DW) (Control) group received 15 mL of DW; sodium hypochlorite (NaOCl)+ethylenediaminetetraacetic acid (EDTA) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW; passive ultrasonic irrigation (PUI) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW, and each irrigant was agitated with an ultrasonic file; and laser activated irrigation (LAI) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW, and each irrigant was irradiated with Nd: YAG laser. Fiber posts were luted with SARC, and a push-out test was performed. Data was analyzed using one-way analysis of variance and Tukey HSD test. RESULTS: The bond strength values for the groups obtained were as follows: Control (10.04 MPa), NaOCl+EDTA (11.07 MPa), PUI (11.85 MPa), and LAI (11.63 MPa). No statistically significant differences were found among all experimental groups (p>0.05). The coronal (12.66 MPa) and middle (11.63 MPa) root regions indicated a significantly higher bond strength compared with the apical (9.16 MPa) region (p<0.05). CONCLUSIONS: Irrigant activation methods did not increase the bond strength of fiber post to canal.

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.

Dentinal tubule penetration of endodontic sealers after nonthermal plasma treatment: A confocal laser scanning microscopy study.

One of the factors affecting the success of endodontic treatment is to fill the root canal system hermetically. The aim of this in vitro study was to evaluate the effect of nonthermal plasma (NP) on dentinal tubule penetration of root canal sealers using confocal laser scanning microscopy. Forty mandibular premolar teeth were selected and the root canals were prepared with large-Waveone-Gold rotary-files. Specimens were divided into four experimental groups according to sealer and NP treatment (n = 10). G1: AH-Plus (AH) G2: nonthermal plasma application + AH-Plus(AH-P) G3: Endosequence-BC(BC) G4: nonthermal plasma application + Endosequence-BC(BC-P). Cold lateral-condensation technique was used for the obturation of root canals. The roots were sectioned horizontally and the sections were examined under confocal laser scanning microscopy. The maximum tubule penetration and percentage of penetration values were obtained from the microscopy images and were statistically analyzed with repeated measurements-ANOVA and the Tukey (HSD) test (p < 0.05). The percentages of dentinal tubule penetration of the groups were not statistically different. The maximum tubule penetration of the AH-P was statistically lower than that of the BC-P (p < 0.05). Plasma application had no affect on the percentage of dentinal tubule penetration. Under the conditions of this in vitro Endosequence-BC sealer showed higher maximum tubule penetration values than AH-Plus after NP treatment. Percentage of dentinal tubule penetration values of experimental groups was similar.

Evaluation of Intra Root Canal Er,Cr:YSGG Laser Irradiation on Prosthetic Post Adherence.

PURPOSE: In clinical prosthetics procedures, including endodontics and post fixation, the presence of a smear layer can reduce the post bond strength. An Er,Cr:YSGG laser, which emits at 2780 nm, can promote a smear-layer-free surface due to the ablation process. Considering these aspects, the purpose of this work was to evaluate the influence of Er,Cr:YSGG laser irradiation using either a radial or an axial fiber tip on the bond strength of three resin cements to the fiber-reinforced composite posts. MATERIALS AND METHODS: Ninety recently extracted single rooted human teeth had their root canal instrumented and were randomly distributed into nine experimental groups, in which three resin cements (total-etching Variolink II, self-etching Panavia F, and self-adhesive RelyX Unicem Aplicap) and three root canal treatments (no treatment, laser irradiation using the radial fiber tip, laser irradiation using the axial fiber tip) were used. Specimens were then sectioned into three sections (cervical, middle, and apical thirds) with two slices on each section. A push-out test was performed on each slice, and the values were recorded as MPa. The push-out data were analyzed by a Ryan-Joiner normality test followed by a two-way ANOVA test and Tukey pairwise comparison. The statistical analysis was performed on each third section separately, with a 5% significance level. RESULTS: Laser irradiation with axial fiber tip significantly increased the post bond strength of RelyX Unicem Aplicap on middle third of specimens (p < 0.001) when compared to other root canal treatments (unlased or irradiated with radial tip). Considering the Panavia resin cement, laser irradiation with either axial or radial tips promoted a significant increase on the post bond strength of middle third when compared to unlased specimens (p < 0.001); however, laser irradiation did not influence the post bond strength of Variolink resin cement. CONCLUSIONS: The use of the Er,Cr:YSGG laser for clinical prosthetics procedures enhances the post bond strength of Panavia and RelyX Unicem Aplicap resin cements, mainly at middle third of roots, and does not interfere with the bond strength of Variolink resin cement. For the RelyX Unicem Aplicap system, the use of axial tip is most advantageous and can be recommended for future clinical application.

Bactericidal efficacy of three parameters of Nd:YAP laser irradiation against Enterococcus faecalis compared with NaOCl irrigation.

The success of endodontic treatment depends on the thorough removal of microorganisms from the root canal system. The search for new ways to eliminate the microorganisms is therefore justified. Nd:YAP is a laser that uses yttrium aluminum perovskite, doped with neodymium crystal, as active laser medium. We used the Nd:YAP laser in an in vitro experiment to evaluate the bactericidal effect of three parameters of Nd:YAP laser-activated irrigation on biofilms of Enterococcus faecalis in root canals. The canals of 45 extracted human single-root teeth were prepared on a #35 Mtwo instrument and contaminated with E. faecalis for 14 days. Forty infected single-root teeth were then randomly divided into four groups according to the irrigation agitation protocols as follows: 5.25% sodium hypochlorite (NaOCl), Nd:YAP laser (180 mJ) + NaOCl, Nd:YAP laser (280 mJ) + NaOCl, and Nd:YAP laser (360 mJ) + NaOCl. The remaining bacteria were counted immediately using the cell count method. Teeth were firstly spilt and one half examined by scanning electron microscopy (SEM). The other half involved examination of bacterial colonization in dentinal tubules using confocal laser scanning microscopy (CLSM). Nd:YAP laser (280 mJ) + NaOCl and Nd:YAP laser (360 mJ) + NaOCl completely removed the E. faecalis biofilms from the root canal walls and made it the cleanest among the treatment groups. Bacterial reductions in the treatment groups for dentinal tubules are presented in a descending order as follows: Nd:YAP laser (360 mJ) (53.7%), Nd:YAP laser (280 mJ) (51.5%) > Nd:YAP laser (180 mJ) (45.3%) > 5.25% NaOCl (31.9%) > control (19.3%) (p < 0.05). Nd:YAP laser of 280 mJ and 360 mJ showed effective bactericidal effect in removing E. faecalis biofilm from the root canal walls and dentinal tubules.

Effect of ultrasonic and Nd: Yag laser activation on irrigants on the push-out bond strength of fiber post to the root canal

Abstract Objective: This in vitro study aimed to compare the efficacy of irrigants using various irrigation activation methods to the push-out bond strengths of fiber post to root canal luted with self-adhesive resin cement (SARC). Methodology: Forty-eight decoronated human canines were used. The specimens were divided into four groups corresponding with the post-space irrigation process and were treated as follows: distilled water (DW) (Control) group received 15 mL of DW; sodium hypochlorite (NaOCl)+ethylenediaminetetraacetic acid (EDTA) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW; passive ultrasonic irrigation (PUI) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW, and each irrigant was agitated with an ultrasonic file; and laser activated irrigation (LAI) group was treated with 5 mL of 5.25% NaOCl, 5 mL of 17% EDTA, and 5 mL of DW, and each irrigant was irradiated with Nd: YAG laser. Fiber posts were luted with SARC, and a push-out test was performed. Data was analyzed using one-way analysis of variance and Tukey HSD test. Results: The bond strength values for the groups obtained were as follows: Control (10.04 MPa), NaOCl+EDTA (11.07 MPa), PUI (11.85 MPa), and LAI (11.63 MPa). No statistically significant differences were found among all experimental groups (p>0.05). The coronal (12.66 MPa) and middle (11.63 MPa) root regions indicated a significantly higher bond strength compared with the apical (9.16 MPa) region (p<0.05). Conclusions: Irrigant activation methods did not increase the bond strength of fiber post to canal.