The use of the erbium, chromium:yttrium-scandium-gallium-garnet laser in endodontic treatment

Impact of Ligand Substitution and Metal Node Exchange in the Electronic Properties of Scandium Terephthalate Frameworks

The search for sustainable alternatives to established materials is a sensitive topic in materials science. Due to their unique structural and physical characteristics, the composition of metal-organic frameworks (MOFs) can be tuned by the exchange of metal nodes and the functionalization of organic ligands, giving rise to a large configurational space. Considering the case of scandium terephthalate MOFs and adopting an automatized computational framework based on density-functional theory, we explore the impact of metal substitution with the earth-abundant isoelectronic elements Al and Y, and ligand functionalization of varying electronegativity. We find that structural properties are strongly impacted by metal ion substitution and only moderately by ligand functionalization. In contrast, the energetic stability, the charge density distribution, and the electronic properties, including the size of the band gap, are primarily affected by the termination of the linker molecules. Functional groups such as OH and NH2 lead to particularly stable structures thanks to the formation of hydrogen bonds and affect the electronic structure of the MOFs by introducing midgap states.

Comparative Evaluation of Bacterial Reduction by Laser-Activated Irrigation Technique (LAI) With Conventional Needle Irrigation (CNI) in Single-Rooted Teeth With Pulpal Necrosis: A Single-Blinded Randomized Controlled Trial

Aim  To compare the bacterial reduction in single-rooted teeth with pulpal necrosis after laser-activated irrigation technique (LAI) and conventional needle irrigation (CNI). Methodology In this clinical trial (CTRI/2021/09/047767), 32 patients with pulpal necrosis were enrolled. Under complete aseptic conditions, access cavity preparation was done and the baseline sample S1 was collected from the root canal using paper points. After chemo-mechanical preparation they were allocated into two groups, following block randomization; Group A - CNI with 27 gauge side-vented needle, Group B - LAI with pulsed Er,Cr:YSGG (erbium, chromium:yttrium-scandium-gallium-garnet) (2780 nm) laser. After irrigant activation, canals were dried and a second sample S2 was taken using paper points. Microbial analysis using quantitative polymerase chain reaction (qPCR) was done to quantify the bacterial reduction among the two groups. Inter-group and intra-group analysis was done using the independent student t-test and Bonferroni test, respectively. The data was represented in terms of quantification cycle (Cq) values, which are inversely proportional to the microbial count.  Results There was no significant difference in S1 between the two groups (mean difference=0.0205; p=0.912). There was a significant difference in S2 between the two groups for the organisms (mean difference=0.8042; p=0.000). The mean percentage of bacterial reduction in CNI was 10.82% and in LAI it was 25.92%.  There was a significant difference in S1 through S2 within the two groups for the organisms (p=0.000). The mean difference of Cq value is high for LAI compared to CNI (1.3494).  The fold change was calculated by taking the ΔCq value and ΔΔCq value after the logarithmic transformation of the Cq value. LAI showed lower levels of DNA at S2 similar to CNI. There is no significant difference in mean fold change between CNI and LAI (p=0.564).  Conclusion This clinical trial concluded that both LAI and CNI were effective in bacterial reduction. There was greater bacterial reduction with LAI (25.92%) than with the CNI (10.82%) in single-rooted teeth with pulpal necrosis using qPCR analysis.

Investigating the effect of Er,Cr:YSGG laser agitation of sodium hypochlorite on the removal of mature biofilm in the complex root canal systems using atomic force microscopy

Background

Endodontic infections caused by remaining biofilm following disinfection with chemical fluids encourage secondary bacterial infection; hence, employing laser pulses to activate the fluids is advised to improve microbial biofilm clearance. This study investigated the performance of Er,Cr:YSGG laser in photon-induced photoacoustic streaming (PIPS) agitation of 5.25% sodium hypochlorite (NaOCl) to enhance the removal of mature Enterococcus faecalis (E. faecalis) biofilms in complex root canal systems.

Methods

The mesial roots of the lower first and second molars were separated and inoculated with E. faecalis bacteria for 30 days. The roots were irrigated with 5.25% NaOCl, some of them were agitated with passive ultrasonic irrigation (PUI), and the other roots were agitated by Er,Cr:YSGG laser using PIPS at 60 µs/pulse, 5 Hz, and 0.25, 0.5, 0.75, 1, and 1.25 W. An atomic force microscope (AFM) was used as a new method to obtain the results in the isthmus area; the results that have been obtained from each group were compared with each other. ANOVA was utilized to compare the means of the test groups.

Results

Based on the AFM and SEM analyses, laser agitation and passive ultrasonic activation groups have shown higher antimicrobial efficacy than the conventional syringe irrigation group (P<0.05).

Conclusion

Based on the findings of this investigation, the agitation of 5.25% NaOCl solution by Er,Cr:YSGG laser in PIPS at (60 µs/pulse, 5 Hz, 1.25 W) offers better mature bacterial biofilm removal in the mesial root of lower human molars than the same irrigant with syringe irrigation and passive ultrasonic activation technique.

Effect of preparation size on the removal of accumulated hard-tissue debris from the mesial root canal system of mandibular molars using SWEEPS technology

OBJECTIVES

This study assessed the influence of preparation size on the efficacy of shock wave-enhanced emission photoacoustic streaming (SWEEPS) and conventional irrigation (CI) on removal of accumulated hard tissue debris (AHTD) from isthmus-containing mandibular molars using micro-computed tomographic analysis.

MATERIALS AND METHODS

Sixty extracted mandibular molars with two mesial canals connected by an isthmus were selected. Canals were shaped with Mtwo instruments (VDW, Munich, Germany) up to sizes 25/.06, 40/.04 or 40/.06 (n = 20), and specimens were distributed into 2 final irrigation groups (n = 10): SWEEPS and CI. Roots were scanned at a resolution of 10.5 µm before and after preparation and final irrigation. Data sets were co-registered, and the percentage reduction of AHTD calculated for each specimen was statistically compared using analysis of variance with a of 5% significance level.

RESULTS

The preparation size did not significantly influence the percentage reduction of AHTD (p < 0.05), whereas the final irrigation technique had a significant effect on debris removal (p < 0.05). A significant reduction of AHTD was achieved after final irrigation in all groups (p < 0.05); however, SWEEPS was associated with a significantly greater percentage reduction of debris than CI (p < 0.05). None of the specimens presented a completely clean isthmus.

CONCLUSIONS

Removal of AHTD was not significantly affected by the preparation size. SWEEPS was associated with significantly less debris than CI.

CLINICAL RELEVANCE

SWEEPS performed significantly better than CI regarding the removal of AHTD from isthmus-containing mandibular molars irrespective of the preparation size.

In Vitro Comparison of the Wettability of a Bioceramic Root Canal Sealer on Dentin With and Without Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) Laser Irradiation

Introduction: To evaluate and compare the wettability of bioceramic root canal sealer (BioRoot™ RCS, Septodont, Saint-Maur-des-Fossés, France) on dentin with and without erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation using different frequencies and energies.

Methods: A hundred single-rooted tooth samples were divided into five groups of 20 samples each. Each group was treated with different methods before sealer application as follows: Group 1: Treated with 2 ml 17% ethylenediaminetetraacetic acid (EDTA) irrigant for one minute (control group); group 2: Irradiated with Er:YAG laser for one minute (8 Hz frequency and 200mJ energy); group 3: Irradiated with Er:YAG laser for one minute (8 Hz frequency and 400mJ energy); group 4: Irradiated with Er:YAG laser for one minute (16 Hz frequency and 200mJ energy); group 5: (n=20) samples irradiated with Er:YAG laser for one minute (16 Hz frequency and 400mJ energy). Bioceramic root canal sealer application was done onto the treated dentin specimen using a micropipette. The contact angle of the drop of the sealer with the dentin surface was measured after five minutes using a contact angle analyzer.

Results: There was no significant difference in wettability between Er:YAG laser using 8Hz frequency and 200mJ energy and Er:YAG laser using 8Hz frequency and 400mJ energy. However, there was a significant difference between the other two groups of Er:YAG laser using 16Hz frequency and 400mJ energy and Er: YAG laser using 16Hz frequency and 200mJ energy.

Conclusion: Contact angle was found to be lowest in the group that was irradiated with Er:YAG laser for one minute (16 Hz frequency and 400mJ energy) before the sealer application. The test findings demonstrated that the control group had the highest contact angle (low wettability) and it was statistically significant with all other groups.

Dentinal Tubule Penetration and Dislocation Resistance of a New Bioactive Root Canal Sealer Following Root Canal Medicament Removal Using Sonic Agitation or Laser-Activated Irrigation

Objective:

To investigate the influence of sonic agitation or laser-activated irrigation techniques on the removal chlorhexidine (CHX) and modified triple antibiotic paste (mTAP) on the sealer penetration depth and dislocation resistance of Guttaflow Bioseal.

Methods:

Single-rooted mandibular premolars (n=96) were prepared with rotary nickel titanium instruments and randomly divided into two groups (n=48) based on the intracanal medicaments used: Group 1, mTAP; Group 2, CHX gel. After 7 days, the specimens in each group were divided into three subgroups (n=16) based on the supplementary irrigation technique used to remove the medicaments: laser activated irrigation (Er, Cr: YSGG laser, Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA), sonic agitation (EndoActivator, Dentslpy Sirona Endodontics, PA, USA) and syringe-and-needle irrigation (control) techniques. Canals were filled with single matched-taper gutta-percha cone and a calcium silicate-based sealer (GuttaFlow® Bioseal, Coltène/Whaledent, Langenau, Germany). At the end of three weeks, sealer penetration was investigated using confocal microscopy (n=6), and dislocation resistance was calculated by measuring the push-out bond strength (n=10). Statistical analysis was performed using three-way analysis of variance (ANOVA) and Tukey post-hoc test (P=0.05).

Results:

Laser activated irrigation resulted in significantly higher depth of sealer penetration compared to sonic agitation and syringe irrigation (P<0.01). The average sealer penetration depths were recorded as 846.6 µm, 786.5 µm and 505 µm in the Er, Cr: YSGG laser, EndoActivator and control groups, respectively. The mean bond strength obtained in group 3 (syringe-and-needle irrigation) was significantly less than the other groups (P<0.05). The mean values were 9.08 in the Er, Cr: YSGG laser group, 8.44 in the EndoActivator group and 5.08 in the needle group.

Conclusion:

Er,Cr;YSGG laser irrigation to remove the medicaments was advantageous to other irrigation techniques in sealer penetration and dislocation resistance of the sealer.

Evaluation of Antimicrobial Efficacy and Penetration Depth of Various Irrigants into the Dentinal Tubules with and without Lasers: A Stereomicroscopic Study

Aim

To evaluate and compare the antibacterial efficacy and horizontal depth of penetration of various irrigants into the dentinal tubules when used alone and when combined with lasers.

Materials and methods

An experimental study was done on 42 single-rooted teeth. Access cavity preparation was done and the canals were enlarged up to a ProTaper file size F2 of length 25 mm. They were inoculated with 0.1 mL of Enterococcus faecalis and the samples were randomly assigned into six different groups of seven teeth each. The following irrigation systems were used individually and in combinations—normal saline, sodium hypochlorite, chlorhexidine gluconate, diode laser and erbium, chromium: ytrrium scandium gallium garnet laser (Er,Cr:YSGG laser). The colony-forming units (CFU) of bacteria before and after disinfection and the penetration depth of different groups were determined. Statistical analysis was done by an ANOVA test.

Results

The highest number of CFU of bacteria was shown by the group where saline was used and it also showed the least penetration depth compared to that of the Er,Cr:YSGG laser group.

Conclusion

Er,Cr:YSGG laser when used along with sodium hypochlorite and chlorhexidine gluconate showed the highest reduction in the CFU of bacteria and the greatest penetration depth when observed under a stereomicroscope.

Clinical significance

Laser-assisted irrigation regimes have a high antibacterial efficacy and more penetration depth into the dentinal tubules.

How to cite this article

Subramani SM, Anjana G, et al. Evaluation of Antimicrobial Efficacy and Penetration Depth of Various Irrigants into the Dentinal Tubules with and without Lasers: A Stereomicroscopic Study. Int J Clin Pediatr Dent 2019;12(4):273–279.

Effectiveness of low concentration of sodium hypochlorite activated by Er,Cr:YSGG laser against Enterococcus faecalis biofilm

Bacteria living in biofilms exhibit altered growth phenotypes, while the biofilm provides benefits, the foremost of which is a certain protection against both immune system and killing effect by antimicrobials. Laser-activated irrigation (LAI) and passive ultrasonic irrigation (PUI) have been proposed as alternative methods for cleaning and disinfecting the root canal, as an adjuvant to conventional chemo-mechanical preparation in order to improve debridement and disinfection. Nevertheless, the potential antibacterial effect of LAI using 0.5% of sodium hypochlorite (NaOCl) has received little attention. Glass Pasteur pipettes were used to mimic single-tooth root canal and to build Enterococcus faecalis biofilm. Several irrigants and treatments were assayed for 60 s including (I) Saline, (II) NaOCl 0.5%, (III) NaOCl 5%, (IV) Er,Cr:YSGG, (V) Saline + LAI, (VI) NaOCl 0.5% + LAI, (VII) Saline + PUI, and (VIII) NaOCl 0.5% + PUI. Bacterial reduction was measured by counting the colony-forming units (CFUs). Additionally, AFM visualization and measurement of nano-roughness parameters were used to evaluate LAI effect on bacteria. NaOCl 5% unpowered and NaOCl 0.5% + LAI were capable of eliminating all bacteria, whereas non-activated saline solution and NaOCl 0.5% failed to eliminate E. faecalis. Lower efficiencies were achieved by PUI. Surface analysis by AFM revealed apparent alterations in NaOCl + LAI-treated cells. The Er,Cr:YSGG laser-activated irrigation (LAI) increased the bactericidal efficiency of 0.5% NaOCl against E. faecalis biofilm.

Comparative study of debris and smear layer removal with EDTA and Er,Cr:YSGG laser

Background

To evaluate in vitro, the ability in removing debris and Smear Layer of 17% EDTA and Er,Cr:YSGG laser.

Material and Methods

58 unirradicular teeth were instrumented with MTwo® and divided into 3 groups according to irrigation protocol: 17%EDTA, laser and a combination of 17%EDTA and laser. All samples were analyzed in the apical and middle third with Scanning Electron Microscope. The Chi-cuadrado and McNemar tests were used to determine the statistical analysis and data processing and analysis was performed with the statistical package StatGraphics Centurion XVI.

Results

Debris analysis showed statistical significant differences when compared EDTA vs laser and EDTA vs EDTA+laser in the middle third. The Smear Layer removal showed statistical significant differences in the middle third when compared EDTA vs laser and EDTA vs EDTA+laser.

Conclusions

Laser showed a greater cleaning capacity than EDTA in the middle third; the cleanliness was even better when combined laser with EDTA, so the effect is accumulative.

Key words:Root canal treatment, Smear Layer, Er,Cr:YSGG laser, debridement.

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.

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.

Laser-based Disinfection of the Root Canal System: An Update

Microorganisms have been considered to have played a critical role in the initiation and development of pulpo-periapical diseases. Some evidences have shown that mechanical instrumentation may leave considerable portions of canal surfaces undebrided. Therefore, some supplemental methods, such as the use of chemical solutions and/or lasers, have been introduced to further disinfect the complicated canal anatomy and destroy as many microorganisms as possible. The purpose of this review was to address a brief review of characteristics of lasers and their effects to disinfect the root canal in endodontics.

Endodontic Treatment of an Autogenous Transplanted Tooth Using an Er,Cr:YSGG Laser and Radial Firing Tips: Case Report

OBJECTIVE AND BACKGROUND

Although several surgical techniques have been reported, no study has yet reported alternative strategies for endodontic treatment of autogenous transplanted teeth. Therefore, the aim of this clinical report is to present the long-term endodontic outcome of a nonvital autogenously transplanted third molar treated with an Er,Cr:YSGG laser and radial firing tips (RFTs).

CASE REPORT

Autogenous tooth transplantation can be considered an alternative to restore edentulous areas and, in donor's teeth with complete root formation, root canal treatment should be performed up to 14 days following transplantation. In the present case report, the patient returned only after 6 months, with clinical and radiological signs of apical periodontitis (AP) associated with the transplanted tooth.

METHODS

Instead of traditional endodontic chemical irrigants or medications, the protocol for smear-layer removal and root canal disinfection was based on intracanal irradiation with an Er,Cr:YSGG laser and RFTs.

RESULTS

After 3-years' follow-up, the complete reestablishment of the periodontal ligament and the arrest of the resorptive process could be noticed.

CONCLUSIONS

This protocol has shown to be effective for the endodontic treatment of a transplanted multi-rooted tooth with AP. Further randomized clinical trials should be conducted to clearly demonstrate the effectiveness of this laser-assisted endodontic protocol.

Photoactivated disinfection (PAD) of dental root canal system - An ex-vivo study

AIM

To investigate the efficacy of photo activated disinfection (PAD) in reducing colony-forming unit (CFU) counts of Enterococcus faecalis (E. faecalis) in infected dental root canals. The study compared the efficacy of PAD with conventional endodontic treatment (CET) and also a combination of CET along with PAD.

MATERIAL AND METHODS

53 maxillary incisors were taken for the study. Teeth were divided into 3 groups, CET (Group I) (n = 11), PAD (Group II) (n = 21), and a combination of CET and PAD (Group III) which consisted of (n = 21) samples, Group II and Group III were further divided into 2 subgroups, Group IIa, IIb and Group IIIa, IIIb. Strains of E. faecalis were inoculated in all the root canals. CET group samples were treated by chemo-mechanical preparation (CMP) alone, PAD samples were treated with laser alone at 2 different exposure time (4 min and 2 min). In the combination treatment, samples were treated initially by CET and then by PAD for a time period of 4 min and 2 min. Contents of the root canal were aspirated, diluted and plated in Tryptone Soya Broth (TSB) and plates were incubated for 24 h to observe the bacterial regrowth.

RESULTS

Showed PAD used along with CMP reduced the bacterial load of E. faecalis by 99.5% at 4 min and 98.89% at 2 min.

CONCLUSION

PAD may be an adjunctive procedure to kill residual bacteria in the dental root canal systems after standard endodontic root canal preparation.

An in-vitro evaluation of the effect of 980 nm diode laser irradiation on intra-canal dentin surface and dentinal tubule openings after biomechanical preparation: Scanning electron microscopic study

Context:

Very recently, diode laser has been used for disinfecting the root canals in endodontic treatment and increasing its success rate and longevity utilizing the thermal effect of laser on surrounding tissues.

Aims:

The aim of this study is to evaluate the effect of 980 nm laser irradiation on intra-canal dentin surface – scanning electron microscopic (SEM) - in-vitro study.

Methods:

A total of 40 single-rooted freshly extracted permanent teeth were collected. Teeth were sectioned at the cemento-enamel junction using diamond disc. Root canals of all samples were prepared using hand ProTaper, which were randomly assigned into two groups (n = 20 each). Group 1: Receiving no treatment after biomechanical preparation; Group 2: 980 nm diode laser-treated root canals. Teeth were prepared for SEM analysis to check the size of intra-canal dentinal tubule openings.

Statistical Analysis Used:

Data were analyzed using SPSS V.16 software and compared using Levene's and independent t-test.

Results:

On statistical analysis, width of intracanal dentinal tubule openings in Group 1 (control) was significantly higher than those observed in Group 2 (diode laser-treated) (P < 0.001).

Conclusion:

This study showed that the application of 980 nm diode laser on intra-radicular dentin resulted in ultrastructural alterations resulting in melting of dentin.

Effect of Er,Cr:YSGG laser irradiation with radial firing tips on Candida albicans in experimentally infected root canals

Aim. To compare the disinfection effect of Er,Cr:YSGG laser using radial firing tips with NaOCI in root canals infected with C. albicans and to evaluate the irradiation effect on the dentinal surfaces. Material and Methods. In total seventy-six mandibular premolar teeth were used. In order to standardize the incubation and sterilization procedure, eight teeth were used. Sixty-eight of the root canals were incubated with C. albicans suspension for 72 hours. The specimens were divided into 5 experimental groups. Two groups were constituted as Group 1 was irradiated with 1.5 W laser (n = 8) and group 2, which was irradiated with 2 W laser (n = 8). Two more groups were formed as Group 3 (2 W laser (n = 25) and Group 4 NaOCI (5%) (n = 25). Group 5 (n = 2) did not receive any treatment. Mann-Whitney U and Kruskal-Wallis H tests were used to compare the different laser output powers. Wilcoxon Signed Ranks Test was used in order to compare the Candida cfu/ml levels according to treatment protocols (P < 0.05). Results. Both 1.5 W and 2 W laser resulted in a major reduction of C. albicans without a significant difference. The comparison of the dentin surfaces irradiated with Er,Cr:YSGG laser at two power settings resulted in similar morphological changes. However, NaOCI was found to be more effective in reduction of C. albicans than 2 W laser application. Conclusion. According to the results of the present study, the Er,Cr:YSGG laser with radial firing tips presented less antifungal effects on C. albicans in root canals of infected teeth than NaOCl solution.

Activation of ethylenediaminetetraacetic acid by a 940 nm diode laser for enhanced removal of smear layer

Laser enhancement of ethylenediaminetetraacetic acid with cetrimide (EDTAC) has previously been shown to increase removal of smear layer, for middle-infrared erbium lasers. This study evaluated the efficiency of EDTAC activation using a near-infrared-pulsed 940 nm laser delivered by plain fibre tips into 15% EDTAC or 3% hydrogen peroxide. Root canals in 4 groups of 10 single roots were prepared using rotary files, with controls for the presence and absence of smear layer. After laser treatment (80 mJ pulse(-1) , 50 Hz, 6 cycles of 10 s), roots were split and the apical, middle and coronal thirds of the canal were examined using scanning electron microscopy, with the area of dentine tubules determined by a validated quantitative image analysis method. Lasing EDTAC considerably improved smear layer removal, while lasing into peroxide gave minimal smear layer removal. The laser protocol used was more effective for smear layer removal than the 'gold standard' protocol using EDTAC with sodium hypochlorite (NaOCl). In addition, lasers may also provide a benefit through photothermal disinfection. Further research is needed to optimise irrigant activation protocols using near-infrared diode lasers of other wavelengths.

Minimally Invasive Periodontal Treatment Using the Er,Cr: YSGG Laser. A 2-year Retrospective Preliminary Clinical Study

Minimally invasive surgery (MIS) using the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser (Waterlase MD, Biolase, Irvine, CA) to treat moderate to advanced periodontal disease is presented as an alternative to conventional therapies. To date, there are few short- or long-term studies to demonstrate the effects of this laser in treating and maintaining periodontal health. Electronic clinical records from 16 patients – total of 126 teeth, with pocket depths ranging from 4 mm to 9 mm – were treated with the same protocol using the Er,Cr:YSGG laser. The mean baseline probing depths (PD) were 5 mm and clinical attachment levels (CAL) were 5 mm in the 4 - 6 mm pretreated laser group. The mean baseline probing depths were 7.5 and 7.6 mm for PD and CAL respectfully in the 7 – 9 mm pretreatment laser group. At the 2 year mark, the average PD was 3.2 ± 1.1 mm for the 4-6 mm pocket group and the 7-9 mm pocket group had a mean PD of 3.7 ± 1.2 mm. mean CAL was 3.1 ± 1.1 mm for the 4-6 mm group and 3.6 ± 1.2 for the 7-9 mm group with an overall reduction of 1.9 mm and 4.0 mm respectively. At one and two years, both groups remained stable with PD comparable to the three-month gains. The CAL measurements at one and two years were also comparable to the three-month gains.

Technologic advances in endodontics

This article addresses technologic advances in endodontics pertaining to new and emerging technology. Cone-beam computed tomography and optical occurrence tomography are 2 new imaging technologies that can assist the practitioner in the diagnosis of pulpal disease. The self-adjusting file and the Apexum device can be used for instrumentation and bulk debridement of an apical lesion, respectively. Neodymium:yttrium-aluminum-garnet laser, erbium:chromium:yttrium-scandium-gallium-garnet laser, EndoActivator, EndoVac, and light-activated disinfection may assist the practitioner in cleaning the root canal system. Computed tomography-guided surgery shows promise in making endodontic surgery easier, as does mineral trioxide aggregate cement for regenerative endodontic procedures.

Performance assessment of novel side firing safe tips for endodontic applications

During root canal or periodontal treatment, directing laser energy onto the walls of the root canal is essential for effective disinfection. This study assessed the performance of four different fiber modifications that have increased lateral emission, including three designs with safe tips to reduce irradiation directed toward the root apex. Free-running pulsed infrared lasers (Nd:YAG, Er:YAG, and Er,Cr:YSGG) and a diode laser (980 nm) were used in combination with plain ended (forward emitting) laser fibers; conical laser fibers, side firing honeycomb pattern fibers without a safe end; honeycomb fibers with silver coated ends, conical fibers with selectively abraded tips, and selectively abraded honeycomb fibers with silver coated tips (20 fibers for each laser type). Laser emissions forward and laterally were measured, and digital photographs and thermally sensitive paper used to record the emission profiles. Thermochromic dyes painted onto the root surface of an extracted tooth were used to explore the distribution of laser energy with different tips designs. All three safe tipped ends gave reduced emissions in the forward direction (range 17-59%), but had similar lateral emission characteristics. Fiber designs with reduced forward emission may be useful for various dental laser procedures.

Evaluation of antifungal efficacy of erbium, chromium: yttrium-scandium-gallium-garnet laser against Candida albicans

OBJECTIVE

The purpose of this in vitro study was to investigate the ability of Er,Cr:YSGG laser irradiation at different energy settings to eliminate Candida albicans, either with or without 5.25% sodium hypochlorite (NaOCl) treatment.

METHODS

In total, 90 extracted human single-rooted teeth were shaped by using a crown-down technique with HERO Shaper rotary instruments and irrigated with 1 mL of 2.5% NaOCl between each instrument. The specimens were autoclaved and incubated with a suspension of C. albicans (ATCC 90028). Then the specimens were divided into six treatment groups (n = 15 per group): group 1, NaOCl + 1-W laser; group 2, 1-W laser; group 3, NaOCl + 0.75-W laser; group 4, 0.75-W laser, group 5, NaOCl; and group 6, no treatment. Aliquots of the experimental teeth were transferred onto Sabouraud's dextrose agar plates with paper points, and colony-forming units (CFUs) were counted as a measure of antifungal activity. One root from each group, which was not submitted to the sampling procedure, was fixed in glutaraldehyde, split into two halves, and evaluated with scanning electron microscopy (SEM). Statistical analysis was performed by using analysis of variance (ANOVA) and the Dunnett t test. Significance was set at alpha = 0.05.

RESULTS

All the treatment groups resulted in a significant reduction of C. albicans, but no sterilization, and all the groups were significantly different from each other (p < 0.0001). Group 1 (NaOCl and 1-W laser combination) exhibited the greatest reduction, whereas group 5 (NaOCl) resulted in a minimal reduction in CFUs of C. albicans. The SEM observations were in accordance with the microbiologic analysis.

CONCLUSIONS

The 5.25% NaOCl and 1-W laser treatment combination may be a valuable cleaning tool for root canals infected with C. albicans.

Temperature variation on the external root surface during intracanal Er:YAG laser irradiation

OBJECTIVE

To evaluate the temperature changes on the root's external surface during Er:YAG laser irradiation with different tips and pulse repetition rates.

BACKGROUND DATA

There have been limited reports that correlate temperature variations with Er:YAG laser irradiation using different tips and pulse repetition rates.

MATERIALS AND METHODS

Sixty roots of central incisors were sectioned 10 mm from the apex, biomechanically prepared, embedded in acrylic resin, and randomly distributed into six groups: the teeth in group I, group II, and group III were irradiated with an Opus 20 laser with a sapphire tip at 8, 10, and 15 Hz, respectively; the teeth in group IV, group V, and group VI were irradiated with the fiberoptic tip of a Kavo Key laser at 6, 10, and 15 Hz, respectively. Laser irradiation was applied for 20 sec to all teeth and temperature changes were recorded with thermocouples in the root surfaces.

RESULTS

There were significant differences (p < 0.05) among pulse repetition rates: 6 and 8 Hz (2.36 degrees +/- 0.91 degrees C), 10 Hz (4.92 degrees +/- 1.60 degrees C), and 15 Hz (8.23 degrees +/- 2.78 degrees C); and radicular thirds: apical (8.33 degrees +/- 2.69 degrees C), middle (4.70 degrees +/- 1.60 degrees C), and cervical (2.48 degrees +/- 0.83 degrees C). No significant differences were seen between the two types of laser tips used (p > 0.05).

CONCLUSION

The temperature changes on root external surfaces remained above the critical threshold (13 degrees C) during Er:YAG laser irradiation, except for irradiation with 15 Hz in the apical third. However, the type of Er:YAG laser tip used (sapphire or fiberoptic) did not affect the temperature variation.