Innovative wavelengths in endodontic treatment

Chitosan nanoparticles, Rose Bengal-chitosan activated photodynamic therapy as final irrigant on pushout bond strength, smear layer removal efficacy and antibacterial effectiveness against E.faecalis

AIM

Impact of final root canal disinfectants diode laser (DL), Rose Bengal photosensitizer (RBP), Chitosan Nanoparticles (CNPs), and CNPs modified RBP on Enterococcus faecalis (E.faecalis) survival rate, smear layer (SL) removal efficacy and push out bond strength (PBS) of resin sealer to the radicular dentin.

MATERIAL AND METHOD

Single rooted seventy-five human mandibular premolar teeth were sectioned at a level of cementoenamel (CEJ) and root canal treatment was performed using a ProTaper rotary instrument. To assess the antibacterial efficiency E.faecalis inoculation was performed using a pour plate method. The samples were arbitrarily allocated into five groups based on the final disinfectant received (n = 15) Group-1 (NaOCl+17 % EDTA), Group-2 (NaOCl+DL), Group-3 (NaOCl+CNPs), Group-4 (NaOCl+RBP activated by DL) and Group-5 (NaOCl+CNPs-RBP activated by DL). SEM analysis for SL removal was performed on five specimens from each group. Root canal obturation and sectioning were performed at cervical, middle, and apical levels. PBS and failure mode were analyzed using a universal testing machine (UTM) and stereomicroscope respectively. The data was subjected to analysis using one-way analysis of variance (ANOVA) and Tukey's post hoc test.

RESULT

Group 1 (NaOCl+17 % EDTA) (0.36 ± 0.01 CFU/mL) unveiled the maximum survival rate of tested bacteria. However, Group 5 (NaOCl+CNPs-RBP activated by DL) (0.11 ± 0.01 CFU/mL) displayed minimum survival of E.faecalis. The highest SL removal (1.44 ± 0.11) and bond integrity scores (12.23 ± 0.24 MPa) were recorded in the coronal section of Group 5 (NaOCl+ CNPs-RBP activated by DL) treated roots. However, the lowest removal of SL (3.15 ± 1.09) and PBS (7.24 ± 0.09 MPa) were recorded in Group 4 (NaOCl+RBP activated by DL) treated canals.

CONCLUSION

CNPs-RBP activated by DL as the final irrigant provided satisfactory antibacterial activity, SL removal, and bond strength outcomes compared to other tested groups.

Use of final irrigants MTAD, Salvedora Perscia, Malachite green, and Ti-sapphire laser on push-out bond strength of Zirconia post

AIM

Evaluation of the push-out bond strength (PBS) of zirconia post-bonded to radicular dentin after using different final irrigants (MTAD, Malachite green (MG), Ti-sapphire laser and Salvadora persica (S.persica).

MATERIAL AND METHOD

Forty human permanent single-rooted were decoronated above the cement-enamel junction. An experienced endodontist performed all the root canal instrumentation using ProTaper universal rotary files. Canals were irrigated using 5.25% NaOCl solution followed by EDTA as a final sterilant. Obturation with gutta-percha using AH Plus sealer was performed. Post-space preparation was completed using Gates Glidden and specimens were randomly assigned to four groups based on the final disinfectant received (n=10). Group 1: 5.25% NaOCl + MTAD, group 2: 5.25% NaOCl + MG, group 3: 5.25% NaOCl +Ti-sapphire laser, and group 4: 5.25% NaOCl + S. persica. The chemically polymerized resin was used to lute zirconia posts. PBS and failure mode analysis were performed using a universal testing machine and stereomicroscope at 40X magnification. Data were compared between the two groups with 95% CI using one-way analysis of variance (ANOVA) with the Tukey post hoc test. p=0.05.

RESULTS

Group4(5.25% NaOCl+ S.persica) specimens demonstrated the maximum (8.94±0.14 MPa) bond strength. Conversely, the apical third of Group 2 (5.25% NaOCl+ MG) (2.87±0.15 MPa) samples revealed the minimum bond strength scores. Intergroup comparison exposed that Group 1 (1.3% NaOCl+ MTAD), Group 3 (5.25% NaOCl+Ti-sapphire laser), and Group 4 (5.25% NaOCl+ S. persica) at all three-thirds unveiled no significant difference in PBS (p<0.05).

CONCLUSION

Ti-sapphire laser and Salvedora Persica possess the potential to be used as a final root canal irrigant to improve the push-out bond strength of zirconia post-to-root dentin.

Nd:YAG laser therapy on postoperative pain, swelling, and trismus after mandibular third molar surgery: a randomized double-blinded clinical study

This study aims to evaluate the effect of Nd:YAG laser therapy (NdLT) on postoperative pain, swelling, and trismus after mandibular third molar (M3) surgery. Three hundred patients were randomly divided into the Nd group (n = 100), medication group (n = 100), and Nd+medication (Nd+m) group (n = 100). The WHARFE classification system was used to assess surgical difficulty. After surgery, the Nd group was irradiated by the Nd:YAG laser in very long-pulsed mode (VLP, pulse duration 1 ms, 20 Hz, 4 W, R21-C3) in 6 regions of the extraction socket with a total energy of 300 J. For the medication group, dexamethasone 0.75 mg and loxoprofen 60 mg were prescribed immediately and every 12 h thereafter for 3 days. The Nd+m group received both treatments mentioned above. Pain assessment was performed at 6, 24, 48, and 72 h postoperatively using the visual analog scale (VAS). Swelling was evaluated by changes in the distance from (1) the tragus to the labial commissure, (2) the tragus to the pogonion, and (3) the mandibular angle to the lateral canthus preoperatively and 72 h postoperatively. Trismus was assessed by the change in maximum mouth opening. Groups Nd and Nd+m had lower VAS scores at 6 h, 24 h, and 48 h (F = 13.80, p = 0.00), but the difference between the two groups was not significant (F = 1.34, p = 0.11). However, no significant difference was observed at 72 h (p = 0.10). There was no significant difference in swelling or trismus among the three groups (p > 0.05). NdLT is an effective approach to improve complications after M3 surgery.

Use of final irrigant Potassium Titanyl Phosphate laser; Sapindus Mukorossi and Fotoenticine on the bond values of zirconia post-to-canal dentin

AIMS

Assessment of the efficacy of final root canal irrigants Sapindus mukorossi (SM), Potassium titanyl phosphate laser (KTPL), and Fotoenticine (FTC) on the push-out bond strength (PBS) of zirconia post.

MATERIALS AND METHODS

The root canal procedure was initiated using the 10 K file and the working length was determined on single-rooted human premolar teeth after decoration. The canals were then enlarged using ProTaper universal system and filled using single cone gutta-percha (GP) and AH Plus resin sealer. Post space was prepared by removing 10mm of GP from the canal. All the teeth were then allocated into four groups based on the final irrigating regime used (n=10) Group 1: 5.25% NaOCl+17% EDTA, Group 2: 5.25% NaOCl + KTPL, Group 3: 5.25% NaOCl + FTC and Group 4: 5.25% NaOCl+ SM. Zirconia posts were cemented in the canal space. The specimens were sectioned and implanted in auto-polymerizing acrylic resin. A universal testing machine and stereomicroscope at 40x magnification were used for PBS and failure mode analysis. ANOVA and Tukey post hoc test were used to make group comparisons(p=0.05).

RESULTS

Group 4 (5.25% NaOCl+ SM) coronal section displayed the highest PBS (9.29±0.24 MPa). However, group 3 (5.25% NaOCl+ FTC) apical third (4.08±0.14 MPa) showed the lowest bond values. Group 2 (5.25% NaOCl+ KTP laser) and Group 3 at all three-thirds unveiled no significant difference in PBS(p>0.05). However, Group 1 (5.25% NaOCl+17%EDTA) and Group 4 displayed comparable outcomes of bond strength(p>0.05) CONCLUSION: Sapindus mukorossi has the ability to be used as a final root canal irrigant alternative to EDTA. However, future studies are still required to conclude the outcomes of existing research.

Efficacy of Potassium Titanyl Phosphate Laser and Sodium Hypochlorite on Postoperative Pain Intensity Following Pulpotomy in Teeth with Symptomatic Irreversible Pulpitis: A Randomized Clinical Trial

Introduction: This study evaluated the postoperative pain intensity in permanent teeth with symptomatic irreversible pulpitis treated by pulpotomy using physiological saline, sodium hypochlorite (NaOCl), or the potassium titanyl phosphate (KTP) laser. Materials and methods: Ninety patients diagnosed with symptomatic irreversible pulpitis in permanent molars were randomly divided into three groups according to the pulpotomy procedures. Preoperative pain levels were recorded. Complete hemostasis was achieved with physiological saline (control group), NaOCl, or the KTP laser after initial bleeding control. Patients were asked to mark their pain level on the visual pain scale at 6, 24, 48, and 72 h and 7 and 30 days depending on the severity of pain. The permanent restoration was completed after 7 days. Data were statistically analyzed using Kruskal-Wallis, Mann-Whitney U, Friedman, and Bonferroni tests at a significance level of p < 0.05. Results: According to the present study, the statistical difference between the groups in terms of preoperative pain and percussion pain levels was insignificant (p > 0.05). There was no significant difference between groups in terms of demographic data (p > 0.05). The postoperative pain level of the KTP laser group was significantly lower at 6 h compared with the saline group (p < 0.05). There was no significant difference between groups in terms of the postoperative pain level at other time intervals (p > 0.05). The highest pain scores were observed in all groups at 6 h (p < 0.05). Conclusions: The KTP laser can be preferred primarily for reducing postoperative pain in pulpotomy treatments. The KTP laser or NaOCl-assisted pulpotomy can be an effective treatment for pain reduction in permanent teeth with symptomatic irreversible pulpitis. This report is registered at clinicaltrials.gov (ID: NCT05424796).

Caries-affected dentin disinfection using Triphala, Indocyanine green, and Potassium Titanyl Phosphate laser and their effect on adhesive bond strength

AIM

To assess the impact of new cavity sterilization types using ozone water (OW), Potassium Titanyl Phosphate laser (KTPL), Triphala, and indocyanine green photosensitizer (ICGP) on adhesive bond strength.

MATERIALS AND METHODS

Fifty human permanent molars were included based on the criteria of International Caries Detection and Assessment System (ICDAS) scores 4 and 5 visual examinations, surface hardness valuation, staining by a caries detector solution, and radiographs. Caries-affected dentin (CAD) samples were randomly distributed into groups based on methods of disinfection (n = 10). Group 1: chlorhexidine, group 2: ow, group 3: KTPL, group 4: Triphala, and group 5: ICGP. Following disinfection, specimens were applied with Adper prime and bond NT and then restored with resin composite. All specimens were positioned in a jig of the universal testing machine for shear bond strength (SBS). The debonded samples were analyzed under a stereomicroscope at 40x magnification to determine the type of failure. Analysis of variance (ANOVA) and Tukey HSD tests were used keeping the level of significance p < 0.05.

RESULTS

The highest bond of adhesive resin was displayed by group 2 specimens cleaned using OW (16.71 ± 0.19 MPa). Whereas, the lowest bond integrity was observed by group 5 specimens disinfected using ICGP (11.21 ± 0.16 MPa). It was observed samples disinfected with OW (16.71 ± 0.19 MPa) in group 2 and samples in group 4 (16.09 ± 0.26 MPa) treated with Triphala displayed comparable outcomes of bond strength (p > 0.05). It was observed that group 2 (70%) and 4 (80%) treated specimens accounted mostly for cohesive failure. However, groups 1 (80%), 3 (60%), and 5 (70%) displayed an adhesive failure pattern.

CONCLUSION

OW and Triphala displayed better bond integrity of adhesive resin to CAD and therefore have the potential to be used as a cavity disinfectant in clinical settings. However, ICGP and KTPL displayed weak bonds of adhesive to CAD. More work is needed to extrapolate the findings of the present study.

Disinfection of caries-affected dentin using potassium titanyl phosphate laser, Rose bengal and Ozonated water on shear bond strength of deciduous teeth

AIM

To assess the efficacy of disinfection of caries-effected dentin (CAD) using KTP laser and different decontamination methods using ozonated water (OW), Rose Bengal photosensitizer (RBP), chlorhexidine (CHX), and Er, YAG laser on the shear bond strength (SBS) of adhesive resin bonded to deciduous teeth.

MATERIAL AND METHODS

A total of 50 extracted and radiographically verified carious primary molars were collected and scrutinized according to ICDAS criteria. Specimens were allocated randomly into five groups (n = 10) as per the type of CAD disinfectants. KTP laser, OW, RBP, CHX (control), and Er, YAG laser. After cavity sanitization, a resin adhesive (prime and bond NT) was smeared on the dentinal exterior followed by incremental composite filling. SBS evaluation was performed by employing specimens in the universal testing machine. The debonded surface was assessed under 40x magnification in a stereomicroscope to ascertain fracture mode. Statistical analysis was done by using the ANOVA and the Post Hoc Tukey multiple comparison tests (p < 0.05).

RESULTS

The highest SBS was exhibited by group 2 i.e., when OW was employed for CAD disinfection (10.25 ± 0.24 MPa). Whereas, the lowest SBS bond value was unveiled by samples in group 3 when RBP was applied for dentin surface sanitization (7.85 ± 0.59 MPa).CAD disinfection with KTP laser (8.25 ± 0.41 MPa), CHX (8.19 ± 0.73 MPa), and RBP displayed comparable bond values (p > 0.05).

CONCLUSION

Ozonated water and Er, YAG laser could be employed as cavity disinfectants in primary teeth as they demonstrated better shear bond strength without jeopardizing the adhesive binding capacity of restorative resins bonded to caries-affected dentin.

Adjunctive use of Er, Cr: YSGG laser, Potassium titanyl Phosphate laser, and photosensitizer on extrusion bond strength of radicular dentin to bioceramic sealers

AIM

To assess the impact of adjunctive final root canal disinfection regime curcumin photosensitizer (CP) activated by Photodynamic therapy (PDT), Er, Cr: YSGG laser (ECL), and Potassium titanyl Phosphate (KTP) laser on the bond integrity of two endodontic Bioceramic (BC) sealers.

MATERIALS AND METHOD

Decoration of eighty human single-rooted teeth was performed up to a cementoenamel junction. After instrumentation, all samples were irrigated with 2.25% NaOCl solution followed by 17% EDTA. The specimens were divided arbitrarily into 8 groups (n = 10) based on the adjunctive final irrigation method used. Group 1 and 5 (Control): No adjunctive regime, cleaned using 2.25% NaOCl + 17% EDTA, group 2 and group 6: CP activated by PDT, Group 3 and Group 7 using ECL, Group 4 and Group 8: KTP laser. Following disinfection samples in groups 1, 2, 3, and 4 were obturated using Sankin apatite root canal sealer (SARS). Specimens in groups 5, 6, 7, and 8 were obturated using Pro-root endo sealer (PRES). Sectioning of samples was performed. The sectioned specimens were subjected to a compressive loading exerted via a steel plunger moving at a 0.5 mm/min crosshead speed till debonding. Means and standard deviations (SD) of EBS of BC sealer with the root canal dentin were assessed using one-way analysis of variance (ANOVA) and Post Hoc Tukey multiple comparison tests. The level of significance was measured at p = 0.05.

RESULTS

The coronal section of samples in group 5 (Na-E-PRES) exhibited the highest bond value. The lowest PBS was displayed by the middle third of specimens in group 6. Group 1 (Na-E-SARS), group 3 (Na-E-ECL-SARS), group 5 (Na-E-PRES), and group 7 (Na-E-ECL-PRES) exhibited comparable bond values (p>0.05). Whereas, group 2 (Na-E-PDT-SARS) and group 4 (Na-E-PTPL-SARS), group 6 (Na-E-PDT-PRES), and group 8 (Na-E-PTPL-PRES) were found to be comparable (p>0.05).

CONCLUSION

Adjunctive use of Er, Cr: YSGG laser displayed better extrusion bond strength with BC root canal sealer compared to CP activated by PDT and KTP laser. Bond strength is influenced by the type of irrigation.

Gingival Melanin Depigmentation Using a Diode 808-nm Laser: A Case Series

Introduction: Gingival hyperpigmentation is caused by an increase in the amount of melanin production or the number of melanocytes in the epithelium, which can impair smile esthetics. The current study aimed to report the experience of using a diode laser for gingival depigmentation of three different patients. Case Presentation: Three adult patients are presented with hyperpigmentation in labial gingivae of both jaws. The depigmentation was done using a diode laser at a wavelength of 808 nm, fiber diameter of 300 μm, and power of 1 W and in continuous mode. All three patients showed proper resolution of hyperpigmented areas in short- and long-term follow-up sessions. However, degrees of recurrence were noticeable in two cases. Conclusion: The 808-nm diode laser can be utilized safely and efficiently in gingival depigmentation, resulting in an acceptable cosmetic outcome.

Antibacterial efficiency of adjuvant photodynamic therapy and high-power diode laser in the treatment of young permanent teeth with chronic periapical periodontitis. A prospective clinical study

BACKGROUND

The study aimed at determining antibacterial efficiency of adjuvant photodynamic therapy (PDT) and high-power diode laser (DL) in the treatment of chronic periapical periodontitis (CPP) in young permanent teeth.

METHODS

Forty-four young permanent teeth with CPP were randomly divided into three groups (PDT, DL and control). Each tooth underwent standard chemo-mechanical treatment, while within tested groups was additionally treated by PDT or DL. Bacterial identification and quantification were provided by MALDI-TOF spectrometry and plate counting assay, performed after accessing the canal, following chemo-mechanical preparation, and after PDT or DL procedure where applicable.

RESULTS

Thirty-nine young permanent teeth with CCP (patients age 9.77 ± 1.43) completed the study. Before the treatments, 202 isolates belonging to 13 genera/species, including Streptococcus (36), Actinomyces (34), Peptostreptococcus micros (27), Veillonella (25) and Enterococcus faecalis (22), were recovered. Chemo-mechanical treatment reduced CFU count in the all three groups (p < 0.001), but complete eradication was not observed for any of isolated species. Adjuvant PDT and DL completely eradicated isolates of 8 and 6 bacterial genera/species, resulting in complete bacterial elimination from 53.8% and 30.8% of root canals, respectively. In the rest canals, total Δlog CFUs were 4.71 and 4.58.

CONCLUSION

The results indicated that both PDT and DL could be performed as adjuvants to standard endodontic treatment of the young permanent teeth with CPP.

Influence of Laser Irradiation Settings, during Diode-Assisted Endodontics, on the Intraradicular Adhesion of Self-Etch and Self-Curing Luting Cement during Restoration-An Ex Vivo Study

Background: Diode-assisted endodontics is nowadays utilized for pulp space disinfection, but little is known on the bonding potential of this lased root dentin when the tooth is restored with an intracanal polymer post. Objectives: to investigate the influence of diode laser irradiation settings, in laser-assisted endodontics, on the intraradicular bonding of composite materials. Methods: Sixteen two-rooted, maxillary first premolars were collected, prepared up to F4 (Protaper Universal. Dentsply-Maillefer, Ballaigues, Switzerland), and randomly assigned in two groups: group A (chopped mode or short pulse), diode irradiated according to protocol, pulse 25 ms, power 2.5 W, and group B (microchopped mode or ultrashort pulse), pulse 25 μs, peak power 12 W (both groups GentleRay. KaVo Dental, Biberach an der Riss, Germany). Buccal canals were irradiated, palatal ones served as controls. Canals were then obturated, post space was created in all canals, and quartz-fiber posts (ICE light Danville. Danville Materials, San Ramon, CA, USA) were cemented by self-etch self-curing cement (Max Cem Elite. Kerr, West Collins Orange, CA, USA) (Max Cem Elite. Kerr, Brea, CA, USA). A week later, teeth were sectioned horizontally in 1 mm increments. Push-out test was conducted in a Zwick testing machine (Zwick Roell, Ulm, Germany) at 1 mm/min speed, and the force required to dislodge the post from each specimen (F-max) was recorded. Weibull regression models were applied for statistical analyses. Results: Differences in F-max by group (control vs. chopped mode vs. microchopped mode) and height (meaning the apical-to-coronal position of each specimen along the root) were statistically significant (p < 0.05 in all cases). Conclusions: Short pulses (or chopped mode) had a profound positive effect on the quality of intraradicular bonding, while Ultrashort pulses (or microchopped mode) affected it negatively. In addition, apically positioned bonding proved weaker compared with more coronally located specimens.

Evaluation of the Effect of Long-term Use of Three Intracanal Medicaments on the Radicular Dentin Microhardness and Fracture Resistance: An in vitro study

Objectives

The aim of this research was to evaluate the effect of long-term use of three intracanal medicaments on the radicular dentin microhardness and fracture resistance.

Material and methods

A chemomechanical preparation was done using the Protaper rotary instruments up to F3. The teeth were stored in an incubator at 37°C at 100% humidity and were categorized in three groups by random allocation, namely: Triple Antibiotic Paste (TAP), Calcium hydroxide paste (Apexcal) and Ledermix. Following medicament application, the access openings of all teeth were sealed with 4 mm thickness of cavit. The samples were stored for periods of 1 week, 1 month and 3months. Two dentin cylinders measuring 5mm and 3mm were obtained from each sample. The cervical third was used for fracture resistance and the middle third was used for micro hardness evaluation. The microhardness testing was done using a Knoop microhardness tester, and the fracture resistance testing was done using the universal testing machine.

Results

Calcium hydroxide showed maximally negative effect on the physical properties of radicular dentin compared to TAP (p= 0.0100 at one month and Ledermix (p=0.0001 at one month). With an increase in the application time, there was an increased deterioration in the physical properties of radicular dentin.

Conclusion

Long-term placement of calcium hydroxide, Triple Antibiotic Paste, and Ledermix (p= 0.0001at 3 months) significantly affects the microhardness and fracture resistance of radicular dentin.

Effects of laser modalities on shear bond strengths of composite superstructure to zirconia and PEEK infrastructures: an in vitro study

In the last decade, demand for metal-free esthetic restorations has grown considerably due to the development of materials to fulfill the need for an esthetic prosthesis. We examined the effects of erbium-doped yttrium aluminum garnet (Er:YAG), neodymium-doped yttrium aluminum garnet (Nd:YAG), and potassium titanyl phosphate (KTP) laser applications on the shear bond strength (SBS) of nanohybrid composite superstructures to zirconia and PEEK infrastructures. Zirconia and PEEK specimens were prepared with CAD/CAM technology in accordance with ISO 11405 standards. The disc-shaped samples were randomly separated into four groups (n = 8) according to applied laser type: no treatment and Er:YAG, Nd:YAG, and KTP lasers. Nanohybrid composite resin was applied as a veneering material to each infrastructure. After surface treatment of infrastructures by the lasers, the SBS test was carried out to determine the bonding of infrastructures, which were also examined with a stereomicroscope. The SBS were significantly higher in the PEEK specimens treated with the studied lasers. Nd:YAG laser was the most effective method, followed by Er:YAG laser and KTP laser. The lowest SBS value was obtained in the no-treatment group. Stereomicroscopically, the studied lasers produced different irregularities on the infrastructures. PEEK as a framework provides meaningfully higher bonding strength to composite resins compared to zirconia. Nd:YAG, Er:YAG, and KTP, in descending order, are efficacious in increasing the attachment of studied structures.

Histological Ex Vivo Evaluation of the Suitability of a 976 nm Diode Laser in Oral Soft Tissue Biopsies

INTRODUCTION

Laser-induced thermal effects can preclude a safe histological evaluation of biopsy resection margins. The aim of this study was to evaluate the suitability of a 976 nm diode laser in oral soft tissue biopsies in an ex vivo study.

MATERIALS AND METHODS

A 976 nm diode laser (Solase®, Lazon Medical Laser, China) has been used in the contact mode, using a 400 μm fiber tip, at different parameters from 4 to 6 W in the continuous wave (CW), with a fluence between 3184 and 4777 J/cm2, and pulsed wave (PW) mode, with a fluence between 318,4 and 477,7 J/cm2, to obtain 30 samples from fresh pig cadaver tongues. All specimens were subdivided into 6 groups (from A to F), and each group consisted of 5 samples. Two sections were obtained from each sample. A histological analysis was performed using an optical microscope at magnifications of 5x and 10x. Statistical analysis was carried out using Kruskal-Wallis and Dunn's tests.

RESULTS

The results showed that histological readability was optimal in all the samples. The thermal damage was negligible in all groups. The average thermal damage was 208.40 ± 133.81 μm in the epithelial tissue and 330.14 ± 147.45 μm in the connective tissue. The statistical analysis showed no differences between the groups (p > 0.05).

CONCLUSION

A 976 nm diode laser demonstrated good surgical effectiveness that provoked little peripheral damage in the cut edges and allowed a safe histological diagnosis. Clinical Relevance. In oral pathology, many times, there is fear in using the laser to remove some lesions due to its thermal effect on the tissues close to the lesion. This effect is always present in the use of the laser, but the intent is to minimize this effect to have as little alteration as possible on the surrounding tissues.

Bactericidal effect of Er,Cr:YSGG laser irradiation on endodontic biofilm: An ex vivo study

AIM

This ex vivo study aimed to evaluate the of Er,Cr:YSGG laser effectiveness in the decontamination of an endodontic biofilm.

MATERIALS AND METHODS

Seventy-three single rooted human teeth, freshly were chosen. Each tooth was exposed to four associated species in an endodontic biofilm (Enterococcus faecalis, Streptococcus salivarius, Porphyromonas gingivalis, and Prevotella intermedia) and randomly allocated to one of the seven experimental groups. The group 1 (7 teeth) was used to finalize the reliable biofilm-forming technique. The groups 2 and 3 (15 teeth each group) were irradiated with two different Er;Cr:YSGG laser settings (0,75 W - 40 Hz and 4 W - 40 Hz, respectively). The groups 4 and 5 (15 teeth each group) were irrigated with two different solutions and laser irradiated with the same settings (1,5 W - 15 Hz). The group 6 (6 teeth) was the control group treated only with 4 ml 2,5% NaOCl irrigation during 60 s.

RESULTS

The observations of group 2 and 3 specimens showed the ripeness of the biofilm with the presence of Enterococcus faecalis and Streptococcus salivarius in chains but in group 3 thermal edge effects produced by the optic fiber in the canal walls were present. The group 4 specimens observation showed an average cleaning of the root canal walls while on the canal walls of group 5 samples the apical third presented several debris and smear layer and in the centre cracks and melting dentin of the radicular wall were observed.

CONCLUSION

In those experimental conditions, this study, demonstrated that Er,Cr:YSGG laser has a canals decontamination ability when associated to NaOCl irrigation.

Effect of a 980-nm diode laser on post-operative pain after endodontic treatment in teeth with apical periodontitis: a randomized clinical trial

BACKGROUND

This study aimed to assess the effect of a 980-nm diode laser following chemomechanical root canal preparation on the severity of post-operative pain (PP) after root canal treatment (RCT).

METHODS

This study included asymptomatic, single-rooted teeth with a periapical index (PAI) score of 3 or 4. All the patients received RCT, including dressing with calcium hydroxide (Ca(OH)₂), during two visits. The patients were randomly divided into two groups (n:30): a control group, in which the final irrigation was performed using 5 ml of 2.5% sodium hypochlorite (NaOCI), followed by 5 ml of 17% and ethylenediaminetetraacetic acid (EDTA) and 5 ml of distilled water, and a laser group, in which the root canals were irradiated using a 980-nm diode laser after the final irrigation at both visits. The pain levels after both visits were evaluated using a visual analogue scale (VAS) after 8 h, 24 h, 48 h and 7 d. In addition, the time intervals to medication intake were recorded. The collected data were statistically analysed using the chi-square and Mann-Whitney U test (p < 0.05).

RESULTS

The average pain level in the control group 24 h after the first visit was significantly higher than that in the laser group (p < 0.05). The average pain level 24 h and 48 h after the second visit was significantly higher in the control group (p < 0.05). The levels of PP 24 h after the first visit were higher than those after the second visit only in the control group (p < 0.05). After the first visit, analgesic use in the control group was significantly higher after 8 h (40%) and 24 h (23%) as compared with that in the laser group (p < 0.05).

CONCLUSIONS

Root canal irradiation with a diode laser may reduce PP after RCT in single-rooted teeth with a PAI score of 3 or 4.

TRIAL REGISTRATION

Effect of the Diode Laser on Post-operative Pain After Endodontic Treatment in Teeth with Apical Periodontitis: NCT04486196. Registered 24 July 2020-Retrospectively registered, http://clinicaltrials.gov/ct2/show/NCT04486196.

Gingival Melanin Depigmentation by 808 nm Diode Laser: Report of a Case

Gingival hyperpigmentation frequently poses an aesthetic problem, especially in patients with gingival smile. This paper presents the use of a 808 nm pulsed diode laser for gingival depigmentation in a 22-year-old male patient, with a frequency of 20,000 Hz, a peak power of 5 W, and a pulse width of 26 microseconds, using a 400 nm flexible optic fiber. The hyperpigmented gingival tissue was removed without bleeding or postoperative pain. Three weeks later, the gum resumed its normal, firm, and pink appearance. No significant recurrence was noted after a follow-up of 4 months. However, perfect control of this device is necessary to avoid certain consequences such as bone exposure or gingival fenestrations.

Q-Switch Nd:YAG Laser-Assisted Elimination of Multi-Species Biofilm on Titanium Surfaces

(1) Background: The relatively high prevalence of peri-implantitis (PI) and the lack of a standard method for decontamination of the dental implant surface have pushed us to conduct further research in the field. Bacterial biofilms were found to play a primordial role in the etiology of PI. Therefore, the aim is to evaluate the efficacy of a laser-assisted elimination of biofilm protocol in the removal of a multi-species biofilm on titanium surfaces. (2) Methods: In total, 52 titanium discs (grade 4) were used. The study group consisted of 13 titanium disks contaminated with multi-species biofilms and subsequently irradiated with the laser (T + BF + L). The control groups consisted of the following types of titanium disks: 13 contaminated with multi-species biofilms (T + BF), 13 sterile and irradiated (T + L), 13 sterile and untreated (T). Q-Switch Nd:YAG laser Irradiation parameters were the following: energy density equal to 0.597 J/cm² per pulse, power equal to 270 milliwatt per pulse, 2.4 mm of spot diameter, and 10 Hz repetition rate for pulse duration of six nanoseconds (ns). The laser irradiation was made during 2 s of total time in non-contact and at 0.5 mm away from the titanium disc surface. After treatment, presence of biofilms on the disks was evaluated by staining with crystal violet (CV), which was measured as optical density at six hundred thirty nm, and statistical analyses were done. (3) Results: the optical density values were 0.004 ± 0.004 for the study group T + BF + L, 0.120 ± 0.039 for group T + BF, 0.006 ± 0.003 for group T + L, and 0.007 ± 0.007 for group T. For the study group, laser treatment resulted in a total elimination of the biofilm, with mean values statistically significantly lower than those of contaminated titanium surfaces and similar to those of sterile titanium surfaces. (4) Conclusions: Our irradiation protocol provided a significant elimination of the multi-species biofilm on titanium surfaces. Laser treated titanium surfaces were biofilm-free, similar to the sterile ones.

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.

The Effect of Diode and Er,Cr:YSGG Lasers on the Bond Strength of Fiber Posts

Background: Laser irradiation modifies the topography and composition of dentin surface aiming to increase the retention of bonded posts. Objective: To assess the effect of dentin irradiation with Er,Cr:YSGG or diode lasers on the bond strength of fiber posts using self-adhesive resin cement. Materials and methods: Sixty bovine root canals were root-canal treated, post spaces were prepared, and subsequently fiber posts were cemented. The samples were distributed according to the surface treatment: distilled water (control), Er,Cr:YSGG (1.5 W, 20 sec), or diode (1.5 W, 20 sec) lasers. Bond strengths were assessed by pull-out (n = 10) or push-out testing (n = 10). Pearson's correlation was calculated. Failure mode after testing and the depth of tags in the dentinal tubules were analyzed by confocal laser microscopy. Data were submitted to analysis of variance and Tukey's test. A p < 0.05 was considered significant. Results: In the push-out test, Er,Cr:YSGG laser had significantly different higher values (5.43 ± 0.10 MPa) compared to the control (4.79 ± 0.05 MPa). Diode laser values were not significantly different from the other groups (5.12 ± 0.27 MPa). In the pull-out test, there were no significant differences between Er,Cr:YSGG (6.86 ± 2.16 MPa) and diode (8.43 ± 1.77 MPa) lasers, and both had significant differences compared to the control (4.18 ± 1.29 MPa). No correlation was found. Adhesive failures were predominant in all groups, and no significant differences in tag penetration among the groups were found. Conclusions: The Er,Cr:YSGG laser increases the bond strength of resin cement and fiber post to dentin in both tests, compared to control group without laser treatment. Diode laser only enhanced bonding for pull-out test.

Thermal Changes in Root Surface of Primary Teeth During Root Canal Treatment With Diode Lasers: An In Vitro Study

Introduction: Increased temperature due to the application of laser during root canal disinfection may damage periodontium, alveolar bone, and permanent dental germ. The aim of this study was to evaluate the temperature increase of the external surface of primary roots due to the application of 810 nm and 980 nm diode lasers. Methods: A total of 58 extracted human primary teeth were prepared and randomly divided into two groups: (a) 810 nm diode laser and (b) 980 nm diode laser. Then, each group was divided into 4 subgroups based on the location of the temperature measurement, including subgroup 1: external root surface of primary anterior roots (A); subgroup 2: external root surface of posterior teeth at inter-root space (IS); subgroup 3: external root surface of posterior teeth at outer-root space (OS) and subgroup 4: external surface of furcation area of posterior teeth (F). Results: The mean temperature rise in group a (7.02±2.95ºC) was less than that of group b (10.62±4.59ºC) (P<0.001). Also, a significant difference was found between the laser groups in terms of the mean temperature rise of the external root surface at IS, OS and F, with higher temperature increase occurring in all points in laser b. The comparison of irradiation points in each laser showed a higher mean temperature rise for IS than OS, but this difference was only significant in group b (P<0.001). Conclusion: Within the studied parameters, 810 nm and 980 nm diode lasers should be used cautiously in primary root canals because of their temperature rise during their application.

In Vitro Effect of Er:YAG Laser on Different Single and Mixed Microorganisms Being Associated with Endodontic Infections

Objective: The purpose of this in vitro study was to evaluate the antimicrobial effect of activated irrigation with different modes of erbium-doped yttrium aluminum garnet (Er:YAG) laser application on microorganisms related to secondary endodontic infection. Background: Er:YAG laser has been recommended as an adjuvant tool for root canal disinfection during endodontic treatment. Materials and methods: Laser-activated irrigation (LAI) with 300 or 600 μm tips were tested with or without intermittent irrigation with 0.9% sodium chloride (NaCl) solution against different microorganisms (five single strains and dual species (Streptococcus gordonii combined with Actinomyces oris or Fusobacterium nucleatum) in root canals after 3 days of incubation. In a 21-day infection model, LAI was used together with intermittent rinsing with sodium hypochlorite (NaOCl) against the dual-species mixtures; here the incidence of microbial regrowth after up to 7 days was monitored. Results: In the 3-day root infection model, LAI protocols did not show any significant reduction of the microbial load when compared with manual irrigation with saline solution. In the 21-day infection, S. gordonii combined with A. oris were not detectable anymore after applying the LAI protocol with a 600 μm tip (30 mJ/10 pps) up to 7 days after treatment. Conclusions: Application of LAI with a 600 μm tip by using an Er:YAG laser might be advantageous in treatment of endodontic infections.

Evaluation of chemical and morphological changes in radicular dentin after different final surface treatments

The aim of this study was to evaluate the chemical and morphological effects of different lasers as a final surface treatment for endodontic therapy through energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. Twenty-five maxillary canines were selected and instrumented with K3 system. Roots were randomly distributed into five groups (n = 5) according to the surface treatment: GI (distilled water), GII (NaOCl + EDTA), GIII (NaOCl + EDTA + 980 nm diode laser), GIV (NaOCl + EDTA+ 1,064 nm Nd:YAG laser), and GV (NaOCl + EDTA+ 2,780 nm Er, Cr:YSGG laser). Lasers were applied for 20 s and samples were bisected, exposing the treated surface and then subjected to elements quantification by EDS and morphological evaluation by scanning electron microscope (SEM). EDS data were submitted to ANOVA-two way, and SEM scores were submitted to two-way Kruskal-Wallis and Dunn's tests. The EDS analysis showed no difference for the chemical elements and Ca/P ratio between groups (p > .05). Statistical analysis showed more intense results for GV and less intense results for GI (p < .05). The GIII showed an amorphous organic matrix surface, while GV provided greater removal of intertubular dentin forming craters, and GIV promoted dentin fusion. The EDS method used in this study was not able to verify any chemical changes in root canal dentin; Nd:YAG, Er, Cr:YSGG, and 980 nm diode laser were capable of modifying the dentin morphology, correlating characteristics features for each one, which are essential clinical knowledge to establish the correct indication for each case. RESEARCH HIGHLIGHTS: EDS was not able to verify any chemical changes in root canal dentin after 980 nm diode, Nd:YAG and Er;Cr:YSGG laser treatments Nd:YAG, Er, Cr:YSGG, and 980 nm diode laser modified dentin morphology, correlating characteristics features for each one.

The Effect of Er:YAG Laser on Entroccocus faecalis Bacterium in the Pulpectomy of Anterior Primary Teeth

Introduction: Successful root canal therapy depends on the complete elimination of microorganisms such as Entroccocus faecalis, which is impossible to achieve with the traditional methods. Lasers are recently introduced as a new method to solve the problem. The present study is planned and performed to examining the antibacterial effect of Er: YAG laser. Methods: Sixty extracted anterior primary teeth were prepared and sterilized. E. faecalis bacterium was cultured in canals. Samples were randomly divided into two groups. The first group was disinfected by NaOCl 5/25% and Er: YAG laser and the second group just by NaOCl 5/25%. Samples of canal contents were cultured and colony counts were calculated. The results were analyzed statistically by SPSS software and Mann Whitney test. Results: There was no significant difference between colony counts in both groups (P=0.142). But the number of colonies in the first group was lower than in the second group. Conclusion: Although, Er: YAG laser cannot completely eliminate E. faecalis bacterium, its simultaneous use with NaOCl decreases E. faecalis.

Diode Laser Irradiation in Endodontic Therapy through Cycles - in vitro Study

Background/Aim: The aim of this in vitro study was to investigate the influence of irradiation cycles and resting periods, on thermal effects on the external root surface during root canal irradiation of two diode laser systems (940 nm and 975 nm), at output powers of 1 W and 2 W in continuous mode. In previous studies the rising of temperature above 7°C has been reported as biologically accepted to avoid periodontal damage on the external root surface. Material and Methods: Twenty human inferior incisors were randomly distributed into four groups, the 940 nm, and the 975 nm diode laser irradiation, both with an output power of 1 W and 2 W, in continuous mode. The thermographic camera was used to detect temperature variations on the external root surface. Digital radiography of the samples was made. Results: After three cycles of irradiation, at apical third of the root, mean temperature variation by 940 nm diode laser irradiation was 2.88°C for output power of 1 W, and 6.52°C for output power of 2 W. The 975 nm laser caused a higher temperature increase in the apical region, with temperature variation of 13.56°C by an output power of 1 W, and 30.60°C at 2 W, with a statistical significance of p ≤ 0.0001 between two laser systems compared for the same power. The resting periods of 20 s between cycles were enough to lower temperature under 7°C in the case of 1 W and 2 W for 940 nm diode laser, while for 975 nm laser, after three irradiation cycles overheating occurred at both output power rates. Conclusion: Three cycles irradiation of 940 nm diode laser, with resting periods of 20 seconds, allowed safe usage of 1 W and 2 W in CW for endodontic treatment. For 975 nm at a power rate of 1 W, the last resting period drop the temperature near the safe limit and it came under 7°C in a period less than a minute, while at the power of 2 W the resting periods were not long enough for the safe temperature decrease.

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.

Selective photoantisepsis

BACKGROUND AND OBJECTIVE

Selective killing of pathogens by laser is possible due to the difference in absorption of photon energy by pathogens and host tissues. The optical properties of pathogenic microorganisms are used along with the known optical properties of soft tissues in calculations of the laser-induced thermal response of pathogen colonies embedded in a tissue model. The objective is to define the laser parameters that optimize pathogen destruction and depth of the bactericidal effect.

MATERIALS AND METHODS

The virtual periodontium is a computational model of the optical and time-dependent thermal properties of infected periodontal tissues. The model simulates the periodontal procedure: Laser Sulcular Debridement.¹ Virtual pathogen colonies are placed at different depths in the virtual periodontium to determine the depth for effective bactericidal effects given various laser parameters (wavelength, peak power, pulse duration, scan rate, fluence rate) and differences in pathogen sensitivities.

RESULTS

Accumulated background heat from multiple passes increases the depth of the bactericidal effect. In visible and near-IR wavelengths the large difference in absorption between normal soft tissue and Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi) results in selective destruction. Diode laser (810 nm) efficacy and depth of the bactericidal effect are variable and dependent on hemin availability. Both pulsed-Nd:YAG and the 810 nm diode lasers achieve a 2-3 mm deep damage zone for pigmented Pg and Pi in soft tissue without surface damage (selective photoantisepsis). The model predicts no selectivity for the Er:YAG laser (2,940 nm). Depth of the bactericidal effect is highly dependent on pathogen absorption coefficient. Highly sensitive pathogens may be destroyed as deep as 5-6 mm in soft tissue. Short pulse durations enable confinement of the thermal event to the target. Temporal selectivity is achieved by adjusting pulse duration based on target size.

CONCLUSION

The scatter-limited phototherapy model of the infected periodontium is applied to develop a proper dosimetry for selective photoantisepsis. Dosimetry planning is essential to the development of a new treatment modality. Lasers Surg. Med. 48:763-773, 2016. © 2016 Wiley Periodicals, Inc.

Laser Application in Dentistry: Irradiation Effects of Nd:YAG 1064 nm and Diode 810 nm and 980 nm in Infected Root Canals-A Literature Overview

Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria. Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment.

Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System -An in vitro study

Background and aim: Use of laser technology in endodontics has greatly increased in the recent years due to the introduction of new wavelengths and methods and optimal antimicrobial and smear layer removal properties of lasers. This in vitro study aimed to compare the antibacterial effects of diode lasers of 810 nm and 980 nm wavelength on Enterococcus faecalis (E. faecalis) biofilm in the root canal system. Materials and methods: Fifty single-canal human anterior teeth were cleaned, shaped, sterilized and randomly divided into four groups namely two experimental, one positive and one negative control group. The experimental and positive control groups were inoculated with E. faecalis and incubated for two weeks. The experimental group one (n=20) received 810 nm diode laser irradiation (1.5W) while the experimental group two (n=20) was subjected to 980 nm diode laser irradiation (1.5W). The E. faecalis colony forming units (CFUs) were counted in each root canal before and after laser irradiation. Results: Laser irradiation significantly decreased the bacterial colony count in both experimental groups. The reduction in microbial count was significantly greater in 810 nm laser group compared to 980 nm laser group. Conclusion: Irradiation of both 810 and 980 nm lasers significantly decreased the E. faecalis count in the root canal system; 810 nm laser was more effective in decreasing the intracanal microbial load.

In Vitro Evaluation of Dentin Hydraulic Conductance After 980 nm Diode Laser Irradiation

BACKGROUND

Dentin hypersensitivity treatments are based on the physical obliteration of the dentinal tubules to reduce hydraulic conductance. The aim of the present study is to evaluate the hydraulic conductance of bovine root dentin after irradiation with a 980-nm diode laser, with or without associated fluoride varnish.

METHODS

Sixty bovine root dentin specimens were divided into six groups (n = 10 in each group): G1, G3, and G5 (0.5 W, 0.7 W, and 1 W diode laser, respectively); G2, G4, and G6 (fluoride varnish application + 0.5 W, 0.7 W, and 1 W diode laser, respectively). The dentin hydraulic conductance was evaluated at four time periods with a fluxmeter: 1) with smear layer, 2) after 37% phosphoric acid etching, 3) after the treatments, and 4) after 6% citric acid challenge. After the dentinal fluid flow measurements, specimens were also evaluated for mineral composition using energy dispersive X-ray spectroscopy (EDS).

RESULTS

Analysis demonstrated a better result with increased irradiation power (P < 0.001), especially if the diode laser irradiation was associated with the application of fluoride varnish (P < 0.001), ensuring a greater reduction in permeability. Considering the groups treated only with laser irradiation, the 1 W group was superior when compared with the 0.5 W and 0.7 W irradiated groups immediately after treatment (P < 0.001). After citric acid testing, all groups showed similar results, except when comparing the 1 W groups with the 0.5 W groups (P = 0.04). EDS results of the irradiated groups showed an increase in the proportion of calcium and phosphorus ions, which demonstrates a superficial composition modification after laser treatments.

CONCLUSION

Laser irradiation of exposed dentin promoted significant reduction in the dentin hydraulic conductance, mainly with higher energy densities and association with fluoride varnish.

Effects of KTP Laser Bleaching on Traumatized Tooth Enamel

BACKGROUND

Bleaching of traumatized discolored teeth is considered an important issue in esthetic dentistry. Various methods have been introduced for bleaching, some of which may have adverse effects on soft or hard tissues of the tooth.

OBJECTIVES

The objective of the study was to evaluate the effects of KTP laser bleaching on enamel of traumatized teeth.

MATERIALS AND METHODS

A square of 36 mm(2) was chosen on the labial surface of 32 extracted teeth. The corners were drilled in order to indicate the location precisely. The shade of each sample was recorded and the teeth were divided into four groups, each with eight teeth: group A (Smartbleach with KTP laser for 30 seconds), group B (Smartbleach with G-Light for 5 minutes), group C (only Smartbleach for 10 minutes) and group D (control group with no bleaching). After one session of bleaching, shade assessment was performed again. In another experiment on nine teeth, Smartbleach with KTP laser was used for 150 seconds to 1500 seconds. The samples were critically processed and observed by using scanning electron microscope (SEM) to assess enamel damage. Data was statistically analyzed using Kruskal-Wallis test (confidence interval level were set at 95%).

RESULTS

Smartbleach was highly effective when used with KTP laser (P = 0.0419). Enamel damage was observed after frequent KTP bleaching and 750 seconds of KTP bleaching was recognized as the limit by morphological evaluation via SEM, indicating a major difference between under and over 750 seconds of bleaching.

CONCLUSIONS

Application of KTP laser may increase the bleaching effect of Smartbleach, nevertheless it may cause some enamel damage.

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.

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.

Dentinal tubules sealing by means of diode lasers (810 and 980 nm): a preliminary in vitro study

OBJECTIVE

The aim of this study was to evaluate the effect on dentinal surfaces of diode lasers (810 and 980 nm) at different parameters.

MATERIALS AND METHODS

Twenty-four caries-free human impacted wisdom teeth were used. The crowns were sectioned transversely in order to expose the dentin. The smear layer was removed by a 1 min application of ethylenediaminetetraacetic acid (EDTA). Each surface was divided into four quadrants irradiated at a different output power setting for each kind of laser: 0.8, 1, 1.6, and 2 W (energy densities: 2547, 3184, 5092, and 6366 J/cm(2), irradiation speed 1 mm/sec; optical fiber diameter: 200 μm; continuous and noncontact mode). Half of the samples were stained with a graphite paste. All specimens were sent for scanning electron microscopic (SEM) analysis. Pulp temperature increases in additional 20 teeth were measured by a thermocouple.

RESULTS

Diode laser irradiations at 0.8 and 1 W led to occlusion or narrowing of dentin tubules without provoking fissures or cracks. The application of graphite paste increased the thermal effects in dentin. Measurements of pulp temperature showed that irradiations at 0.8 and 1 W for a period of 10 sec in continuous mode increased pulp temperature (T ≤2°C).

CONCLUSIONS

Diode lasers (810 and 980 nm) used at 0.8 and 1 W for 10 sec in continuous mode were able to seal the dentin tubules. These parameters can be considered harmless for pulp vitality, and may be effective in the treatment of dentinal hypersensitivity.

Evaluation of bacterial microleakage of root canals irrigated with different irrigation solutions and KTP laser system

OBJECTIVE

The aim of this study was to evaluate bacterial microleakage of the root canals irrigated with different irrigation solutions and the potassium-titanyl-phosphate (KTP) laser system and filled with gutta-percha and AH26 root canal sealer. In addition, the effect of the irrigation solutions on dentin surface was evaluated with a scanning electron microscope (SEM).

BACKGROUND DATA

A few studies have reported that KTP laser has the capacity to remove the smear layer. Many researchers have demonstrated that propolis has a bactericidal effect. Both are important effects on root canal treatments.

MATERIALS AND METHODS

One hundred and twenty single-root single-canal mandibular premolar teeth were used for this study. The root canals were prepared by Dentaport Root ZX and ProTaper rotary instruments with the crown-down technique. The specimens were randomly divided into five groups of 20 teeth each. Each group was irrigated with 17% ethylenediaminetetraacetic acid (EDTA), 20% propolis, 2.5% sodium hypochlorite (NaOCl), 2% chlorhexidine gluconate (CHX), and KTP laser, respectively. A total of 20 teeth were used as controls-10 positive controls and 10 negative controls-which were irrigated with distilled water. The root canals were filled with gutta-percha and AH-26. The external surfaces of specimens were covered with three layers of nail varnish except the apical third. The teeth were inserted into Eppendorf plastic tubes and suspended in glass bottles containing sterile broth. All specimens were inoculated every 5 days with Enterococcus faecalis. The contamination onset time was continuously recorded, as turbidity was the first indication of contamination in a period of 30 days.

RESULTS

All statistical analysis was performed using the SPSS for Windows version 15.0 software. A χ(2) test was computed and the statistical significance was set at p<0.05. The controls behaved as expected.

CONCLUSIONS

This study showed that different irrigation solutions and KTP laser allowed microleakage of E. faecalis.

Effects of three different irrigating solutions and KTP laser irradiation on apical leakage: an electrochemical study

OBJECTIVE

The purpose of this study was to evaluate the effect of three different irrigating solutions (17% EDTA, 10% citric acid and 2.5% NaOCl) and KTP laser irradiation on apical leakage using an electrochemical method.

MATERIALS AND METHODS

Sixty extracted single-rooted human teeth with mature apices were instrumented up to a size 35 K-file. After using each file and before proceeding to the next, canals were irrigated with 2 ml of 2.5% NaOCl. All teeth were then randomly divided into four groups. In group 1, the root canals were irrigated with a final flush of 17% EDTA. In group 2, the root canals were irrigated with a final flush of 10% citric acid. In group 3, the root canals were irradiated with KTP laser at 1 W, 4.45 J/cm(2). In group 4, the root canals were irrigated with a final flush of 2.5% NaOCl. The root canals were then filled using the cold lateral condensation method. Apical leakage was evaluated using an electrochemical method over a period of 10 days. Data were analysed using Tukey HSD and Friedmann tests with p = 0.05 as the level for statistical significance.

RESULTS

The 17% EDTA and 10% citric acid groups had statistically less apical leakage than the 2.5% NaOCl group at days 7, 8, 9 and 10 (p < 0.05); however, no significant differences were found between the tested groups at the other time intervals (p > 0.05). No significant difference was found between the KTP laser group and other groups tested at all time intervals (p > 0.05).

CONCLUSION

All groups were unable to eliminate apical leakage. However, final irrigation with 17% EDTA and 10% citric acid following root canal preparation reduced postobturation apical leakage compared with 2.5% NaOCl irrigation. When KTP laser and the other three irrigants were compared, no significant difference was found.

Low energy KTP laser in oral soft tissue surgery: A 52 patients clinical study

Objectives: Since 1962 laser appliances have been used for soft tissues surgery of oral cavity with significant advantages compared to the traditional instruments: excellent bleeding control, possibility to avoid the use of suture, good patient compliance thanks to a decrease of intra- and post-operative discomfort and biostimulating effect. Unfortunately, the wavelengths so far used have been seen to cause, in association with an excellent ablation capacity, heat damage of the tissues that can decrease healing process and cause a greater discomfort to patients. The aim of this study was to evaluate the laser-assisted KTP laser surgery at low power in terms of characteristics of intervention and patients compliance. Study design: In this study, we describe the application of a new and recently introduced in dentistry wavelength, the KTP laser (532 nm), used with low power (1 Watt - CW), evaluating the time of interventions and, by a Numerical Rating Scale, the intra and postoperative pain. Results: KTP laser used at low power permits to obtain good pain control during operations that were carried out with only a topic anaesthetic (EMLA, Astratech), as shown in VAS tests. Good healing with limited or absent burning areas in treated portion of tissue. Conclusions: These preliminary study allows us to affirm that KTP laser with low parameters permits to perform oral surgery with good pain control and good wound healing. A greater number of clinical cases are however necessary to confirm the result obtained.

Key words: Laser, KTP, oral surgery, thermal increase.

Apical microleakage and SEM analysis of dentin surface after 980 nm diode laser irradiation

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.