Laterally closed tunnel technique with and without adjunctive photobiomodulation therapy for the management of isolated gingival recession-a randomized controlled assessor-blinded clinical trial.

The objective of this prospective randomized controlled single-center clinical trial was to prove the efficacy of adjunctive photobiomodulation in improving selected outcomes following the use of laterally closed tunnel technique for the management of isolated gingival recession. Nineteen participants (with isolated gingival recession) each treated by laterally closed tunnel technique were randomized to either add on treatment with control (sham laser application) or test group (photobiomodulation with 660 nm diode, 3.5 J/cm2 per point of application). The primary outcome variable was change in recession depth and secondary variables included recession width, width of keratinized gingiva, periodontal biotype, and VAS score for pain assessment and EHS index for early wound healing assessment. Analysis was performed using a linear mixed effects model. There were no significant differences in the gingival recession depth (p = 0.8324) and recession width (p-0.969) at 3-month follow-up. The VAS scores were significantly lower for the test (laterally closed tunnel technique + photobiomodulation) group as compared to control (laterally closed tunnel technique + sham laser) over time (p = < 0.0001) as well as per site (p = 0.0006) The Early Wound Healing Index scores were significantly higher in the test (laterally closed tunnel technique + photobiomodulation) group as compared to control (laterally closed tunnel technique + sham laser) group (p < 0.0001). The adjunctive use of photobiomodulation did not show a better outcome concerning recession depth but appears to provide faster healing of the surgical wounds and better patient comfort. The result needs further evaluation in particular with respect to long-term effect and due to limitation in sample size. Clinical Trial Registry of India: CTRI/2019/11/022012.

The effect of low-level laser radiation on improving inferior alveolar nerve damage after sagittal split osteotomy: a systematic review.

Inferior alveolar nerve (IAN) damage is a common complication occurring after sagittal split osteotomy (SSO) and results in sensory disorders of the jaw region. In recent years, published experimental and clinical evidence suggests that low-level laser (LLL) radiation is effective in nerve recovery. Therefore, the aim of the present study was to review clinical trial studies investigating the effect of LLL radiation on improving the sensory defects of IAN after SSO. The keywords associated with SSO and LLL were searched in PubMed, Medline (via Ovid), Web of Science (WOS), Scopus, and Cochrane Library databases. Then, controlled clinical trial studies published before November 2017 regarding LLL radiation conducted on patients with IAN neuropathy due to SSO were investigated. The articles fulfilling the study criteria were further scrutinized and the necessary information was extracted from them. A total of seven papers were included in the study. The diode laser used had a wavelength range of 760-930 nm, radiation power of 20-200 mw, and radiation energy of 10.2-95 J (per point of radiation). In the mentioned studies, the patients underwent 3-20 sessions of laser irradiation and were monitored for an additional 0-23 months after completion of the laser intervention. The tests performed in the mentioned studies dealt with examining the perceptions of superficial touch and pressure, two-point discrimination, stimulus movement on skin, temperature, and pain. Furthermore, the patients' general awareness regarding sensory perception in the mandibular region was gauged. In six studies, laser irradiation caused relative improvement in the IAN sensory disorder for a subjective test as well as for one or more objective tests. In the reviewed clinical trial studies, LLL was generally found to be effective in improving the IAN sensory disturbance resulting from SSO, though there was no placebo effect.

Influence of grape seed extract in adhesion on dentin surfaces conditioned with Er,Cr:YSGG laser.

The proanthocyanidin (PA)-rich grape seed extract (GSE) is a collagen cross-linking agent that can perform a chemical bond with the dentin's collagen. The objective of this study was to evaluate the influence on shear bond strength (SBS) of the pre-conditioning of GSE, on human dentin surfaces conditioned with Er,Cr:YSGG laser. The sample consisted of 64 non-carious human teeth, divided into eight groups, four groups conditioned with Er,Cr:YSGG laser (4.5 W, 50 Hz, 50 µs, 70% air, 90% water) and four prepared with conventional methods (control). In both groups, a GSE solution was applied before using the two adhesives tested: Clearfil™ SE Bond (CSE) and Scotchbond™ Universal (SU). Subsequently, a SBS test, a scanning electron microscopy, and a statistical analysis were performed. In the laser groups, the best SBS mean (20.08 ± 4.01 MPa) was achieved in the group treated with GSE and CSE. The control group with the application of CSE showed the highest SBS mean (24.27 ± 10.28 MPa), and the group treated with laser and SU showed the lowest SBS mean (12.94 ± 6.51 MPa). Between these two groups there was a statistically significant difference (p = 0.05). However, this was not observed among the laser or control groups. The type of dentin surface preparation can influence the SBS. The CSE showed better SBS in laser and control groups. The presence of GSE did not improve the adhesion on surfaces conditioned with laser, but more studies should be carried out in the future to confirm this conclusion.

Comparison of gingival depigmentation with Er,Cr:YSGG laser and surgical stripping, a 12-month follow-up.

Gingival melanin hyperpigmentation is an esthetic concern for many individuals. In this study, we compared the standard surgical removal method with two different Er,Cr:YSGG laser settings in order to find the best treatment method. In 33 dental arches, the following three treatment groups were comparatively evaluated: (1) surgical stripping, (2) removal with laser setting 1 (4.5 W, 50 Hz, 100% water, 80% air, 60 µs, 800 µm Tip; MZ8), and (3) laser setting 2 (2.5 W, 50 Hz, 20% water, 40% air, 700 µs, 800 µm Tip; MZ8). We comparatively evaluated pain, patient satisfaction and wound healing, treatment time, and the amount of bleeding. Re-pigmentation was evaluated after 1 and 12 months by Hedin and Dummet pigmentation scores. Laser setting 1 had the best results regarding pain and patient satisfaction, although not statistically significant (P > 0.05). Wound healing results were better using lasers compared to surgical stripping (P < 0.05). Laser setting 1 was a faster procedure with mild amounts of bleeding. The least amount of bleeding was seen with laser setting 2. After 1 month, only two cases of the laser setting 2-treated areas showed an isolated pigmented area in the papilla; at 12 months, the mean Hedin indexes were still less than 2 and mean Dummett index less than 1 in all treatment techniques, with the lowest scores seen in the laser setting 1 sites. Based on our results, Er,Cr:YSGG laser can be more convenient for gingival depigmentation compared to surgical blade. Although not statistically significant, laser setting 1 with shorter pulse duration and higher water spray showed better overall results. However, laser setting 2, with longer pulse duration and less water spray, resulted in better coagulative effects and can be used to control bleeding wherever necessary in clinical practice.

Effect of radiant heat on conventional glass ionomer cements during setting by using a blue light diode laser system (445 nm).

The aim of this in vitro study was to evaluate the effect of radiant heat on surface hardness of three conventional glass ionomer cements (GICs) by using a blue diode laser system (445 nm) and a light-emitting diode (LED) unit. Additionally, the safety of the laser treatment was evaluated. Thirty disk-shaped specimens were prepared of each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: group 1 was the control group of the study; in group 2, the specimens were irradiated for 60 s at the top surface using a LED light-curing unit; and in group 3, the specimens were irradiated for 60 s at the top surface using a blue light diode laser system (445 nm). Statistical analysis was performed using one-way ANOVA and Tukey post-hoc tests at a level of significance of a = 0.05. Radiant heat treatments, with both laser and LED devices, increased surface hardness (p < 0.05) but in different extent. Blue diode laser treatment was seemed to be more effective compared to LED treatment. There were no alterations in surface morphology or chemical composition after laser treatment. The tested radiant heat treatment with a blue diode laser may be advantageous for the longevity of GIC restorations. The safety of the use of blue diode laser for this application was confirmed.

The effectiveness of the Erbium:Yttrium aluminum garnet PIPS technique in comparison to different chemical solutions in removing the endodontic smear layer-an in vitro profilometric study.

This study evaluated the degree of endodontic smear layer removal using the Er:YAG PIPS technique (2.94 µm) in comparison with different irrigants. Sixty-four single-rooted teeth were endodontically prepared up to size #40 and were divided into 8 groups (a-h) (n = 8). Groups a, b, c, and d were irrigated with (3 % NaOCl + 20 % EDTA), (0.9 % NaCl), (3 % NaOCl), and (20 % EDTA), respectively. Groups e, f, g, and h were treated with (3 % NaOCl + 20 % EDTA + PIPS), (0.9 % NaCl + PIPS), (3 % NaOCl + PIPS), and (20 % EDTA + PIPS), respectively. The settings of the Er:YAG PIPS technique were (0.3 W, 20 mJ, 15 Hz, 50 µs, no water and air). The root canals were examined under a profilometer to evaluate the degree of smear layer removal using Hülsmann scores. The smear layer was present in the coronal, middle, and apical thirds of groups b, c, f, and g. Groups a, d, e, and h exhibited open dentinal tubules in the coronal and middle thirds. However, none of the apical thirds showed open dentinal tubules. No significant difference was observed between the groups treated only with irrigants and those treated with Er:YAG PIPS and the same irrigants (p ≥ 0.0018). The Er:YAG PIPS technique did not show any improved results in removing the smear layer when compared to the irrigants alone. Moreover, the open dentinal tubules in some groups were a result of the chelating action of 20 % EDTA.

The effect of transmitted Er:YAG laser energy through a dental ceramic on different types of resin cements.

BACKGROUND AND OBJECTIVE: The laser debonding procedure of adhesively luted all-ceramic restorations is based on the ablation of resin cement due to the transmitted laser energy through the ceramic. The purpose of this study was to determine the effect of Er:YAG laser irradiation transmitted through a dental ceramic on five different resin cements. MATERIALS AND METHODS: Five different resin cements were evaluated in this study: G-Cem LinkAce, Multilink Automix, Variolink II, Panavia F, and Rely X Unicem U100. Disc shaped resin cement specimens (n = 10) were fabricated for each group. A ceramic disc was placed between the resin cement discs and the tip of the handpiece of Er:YAG laser device. The resin cement discs were irradiated through the ceramic and the volume of the resin cement discs were measured using a micro-CT system before and after Er:YAG laser irradiation. The volume loss of the resin cement discs was calculated and analyzed with one-way ANOVA and Tukey-HSD tests. RESULTS: The highest volume loss was determined in G-Cem (1.1 ± 0.6 mm3 ) and Multilink (1.3 ± 0.1 mm3 ) (P < 0.05) groups, and the lowest volume loss was determined in Rely X (0.3 ± 0.07 mm3 ), Variolink (0.4 ± 0.2 mm3 ), and Panavia (0.6 ± 0.2 mm3 ) groups (P < 0.05). All resin cements were affected by the laser irradiation resulting in the volume loss of the cement; however, there are significant differences among different resin cements. CONCLUSIONS: All the resin cements tested in this study were effected by the Er:YAG laser irradiation and there were significant differences among the resin cements with regard to ablation volume. Lasers Surg. Med. 47:602-607, 2015. © 2015 Wiley Periodicals, Inc.

Effects of diode laser on direct pulp capping treatment : a pilot study.

At the present time, evidence-based, best practices have yet to be established for maintaining the vitality of teeth by managing caries-associated pulp exposure in permanent teeth. In terms of biomechanical and esthetic considerations, pulp capping has proven to be more effective than root-canal therapy. Given the low success rate of conventional methods, new techniques, such as laser-assisted repairs, should be developed. The purpose of this study was to compare the effectiveness of conventional and diode laser-assisted methods in direct pulp capping of carious teeth. Ten patients ranging in age from 12 to 40 were assigned randomly to experimental and control groups in this clinical trial in which the participants' teeth were treated with different techniques, i.e., conventional treatment and diode 808-nm, laser-assisted treatment. For each of these groups, five cases were chosen for treatment with the same method under rubber dam isolation. The data were analyzed by the runs test using SPSS software. The success rate was significantly different between conventional (60 %) and diode 808-nm, laser-assisted (100 %) groups after one year (P > 0.05). The laser-assisted procedure proved to be more effective than the conventional technique in enhancing the outcomes of pulp-capping therapy in carious exposures.

Laser treatment of dental ceramic/cement layers: transmitted energy, temperature effects and surface characterisation.

In the present paper, we investigate the behaviour of different dental materials under laser irradiation. We have used e.max Ceram, e.max ZirCAD, and e.max Press dental ceramics and glass ionomer cement Ketac Cem in the present study. The dental ceramics were prepared in the form of samples with thickness of 0.5-2 mm. We used two lasers [solid-state laser (Er:YAG, Fidelis III+, Fotona) and an 810- nm diode laser (FOX, A.R.C)] for the transillumination of ceramic samples. It has been shown that the laser energy transmitted through the ceramic material decreases to 30-40% of the original values along with an increase in the thickness of the irradiated sample. Pigmented ceramic samples show more laser energy loss compared to the samples containing no pigment. We investigated the temperature evolution in composite sandwiched ceramic/cement samples under laser treatment. The increase in the irradiation time and laser power led to a temperature increase of up to 80 °C. The surfaces of irradiated ceramic samples were examined with X-ray photoelectron spectroscopy to evaluate changes in chemical composition, such as a decrease in the C signal, accompanied by a strong increase in the Zr peak for the Er:YAG laser, while the 810-nm diode laser showed no change in the ratio of elements on the surface.

Investigations of radicular dentin permeability and ultrastructural changes after irradiation with Er,Cr:YSGG laser and dual wavelength (2780 and 940 nm) laser.

The aim of this study was to assess the effectiveness of dual wavelength (2780 nm Er,Cr:YSGG, 940 nm diode) laser in elimination of smear layer comparing it with Er,Cr:YSGG laser in terms of radicular dentin permeability and ultrastructural changes of root canal walls. Fifty-one sound single-rooted extracted teeth were instrumented up to size F4 and divided into three groups: group Co, non-irradiated samples; group A, irradiated with Er,Cr:YSGG laser; group B, irradiated with the dual wavelength laser. Afterward, the roots were made externally impermeable, filled with 2% methylene blue dye, divided horizontally into three segments reflecting the cervical, middle, and apical thirds then examined under microscope. Using analytical software, the root section area and dye penetration area were measured, and then, the percentage of net dye penetration area was calculated. Additionally, scanning electron microscope investigations were accomplished. Analysis of variance (ANOVA) showed significant differences between all groups over the three root thirds. Dye permeation in dual wavelength laser group was significantly higher over the whole root length: cervical, middle, and apical compared to Er,Cr:YSGG laser group and non-irradiated samples (p < 0.001). Scanning electron micrographs of dual wavelength irradiated samples showed a distinctive removal of smear layer with preservation of the annular structure of dentinal tubules. Er,Cr:YSGG laser root canal irradiation produced uneven removal of smear layer, in efficient cleanliness especially in the apical third. There was no sign of melting and carbonization. Within the studied parameters, root canal irradiation with dual wavelength laser increased dentin permeability.

Effects of Er:YAG and Er,Cr:YSGG laser irradiation on the adhesion to eroded dentin.

Limited information is available regarding the adhesion to eroded dentin. This study aims to evaluate the effect of different surface treatments on eroded dentin morphology and on microtensile bond strength (µTBS) of adhesive systems to this substrate. Ninety-six extracted third molars were randomly divided into eight groups (n = 12) according to the type of surface treatment and the adhesive system: G1 = Control + Clearfil SE Bond [SE], G2 = Diamond bur [DB] + SE, G3 = Er:YAG laser (60 mJ, 2 Hz, 0.12 W, 19.3 J/ cm(2)) + SE, G4 = Er,Cr:YSGG laser (50 mJ, 30 Hz, 1.5 W, 4.5 J/ cm(2)) + SE, G5 = Control + Single Bond [SB], G6 = DB + SB, G7 = Er:YAG + SB, G8 = Er,Cr:YSGG + SB. The erosive cycling was performed by immersion in 0.05 M citric acid (pH 2.3, 10 min, 6x/day) and in supersaturated solution (pH 7.0, 1 h, between acid attacks), during 5 days. Blocks of composite were bonded to the samples according to the manufacturers' instructions. After 24 h-storage in distilled/deionized water (37 °C), stick-shaped samples were obtained and submitted to µTBS test. Each surface treatment was analyzed under scanning electron microscopy (n = 4) and the bond strength values (megapascal) were analyzed by two-way ANOVA and Tukey tests (α = 0.05). All surface treatments lead to changes on eroded dentin. G4 showed the highest bond strength mean (28.3 ± 9.2 MPa), which was statistically significant higher than all the other groups (p < 0.05). The surface treatment with Er,Cr:YSGG laser irradiation (4.5 J/cm(2)/50 mJ/30 Hz/140 µs) prior to bonding with a self-etching adhesive system significantly increases adhesion to eroded dentin, as compared to conventional treatment.

The influence of the energy density and other clinical parameters on bond strength of Er:YAG-conditioned dentin compared to conventional dentin adhesion.

The aim of this in vitro study was to optimise clinical parameters and the energy density of Er:YAG laser-conditioned dentin for class V fillings. Shear tests in three test series were conducted with 24 freshly extracted human third molars as samples for each series. For every sample, two orofacial and two approximal dentin surfaces were prepared. The study design included different laser energies, a thin vs a thick bond layer, the influence of adhesives as well as one-time- vs two-time treatment. The best results with Er:YAG-conditioned dentin were obtained with fluences just above the ablation threshold (5.3 J/cm(2)) in combination with a self-etch adhesive, a thin bond layer and when bond and composite were two-time cured. Dentin conditioned this way reached an averaged bond strength of 23.32 MPa (SD 5.3) and 24.37 MPa (SD 6.06) for two independent test surfaces while showing no statistical significance to conventional dentin adhesion and two-time treatment with averaged bond strength of 24.93 MPa (SD 11.51). Significant reduction of bond strength with Er:YAG-conditioned dentin was obtained when using either a thick bond layer, twice the laser energy (fluence 10.6 J/cm(2)) or with no dentin adhesive. The discussion showed clearly that in altered (sclerotic) dentin, e.g. for class V fillings of elderly patients, bond strengths in conventional dentin adhesion are constantly reduced due to the change of the responsibles, bond giving dentin structures, whereas for Er:YAG-conditioned dentin, the only way to get an optimal microretentive bond pattern is a laser fluence just above the ablation threshold of sclerotic dentin.

Rapid debonding of polycrystalline ceramic orthodontic brackets with an Er:YAG laser: an in vitro study.

The usefulness of erbium-doped yttrium aluminum garnet laser irradiation for debonding ceramic brackets is assessed using a single laser pulse. Damon Clear brackets were chosen for their 85% transmission of 2.94 µm radiation and were bonded to 20 human third molars using the Blugloo adhesive system. Laser parameters comprised of 600 mJ pulse energy with 800 µs duration, 1.3 mm fiber tip. Light microscopy was used to assess Adhesive Remnant Index (ARI) scores, and scanning electron microscope (SEM) images were taken of the cross-section of the enamel-adhesive interface. Nineteen brackets (95%) were successfully debonded with a single laser pulse, while one bracket (5%) required eight pulses for debonding. For all teeth, the SEM analysis showed no signs of damage to the enamel, and ARI scores of three were observed, supporting the result that the laser effect is confined in the adhesive. The presented laser parameters are able to rapidly debond suitable brackets. The debonding mechanism was concluded to be thermomechanical ablation for single pulse debonding.

Shear strength of composite bonded to Er:YAG laser-prepared enamel: an in vitro comparative study.

UNLABELLED: The primary objective of this study is to investigate the adhesion properties between four current generations of bonding systems and enamel surface conditioned by Er:YAG laser, using an energy density comparable to the ablation threshold of enamel. By including an energy density comparable to published adhesion studies, the secondary objective is to compare the adhesion effects of these selected laser conditioning parameters on enamel with other similar published studies. MATERIAL AND METHODS: Buccal sides of randomly selected human molars (N=117) were prepared and divided into nine experimental groups depending on the generations of bonding system represented by the corresponding number (G4, G5, G6, G7) and the additional laser conditioning on the enamel surface represented by laser etch (LE) and laser etch with a higher pulse energy, followed by acid etch (AE), if required. The bonding resin systems and their specific requirements were applied after the enamel surfaces were laser conditioned following a specific set of laser parameters. Composite posts of 1.6 mm in diameter and approximately 6 mm in length were then restored on each of the sample surfaces. After 48 h, the composite assemblies were tested to failure under compression using a knife edge loading head at a cross head speed of 1 mm/min until the composite cylinders were separated from the surface. The data collected were then analyzed using one-way analysis of variance and SAS software program (9.1, TS1M3). RESULTS: No significant difference was found among these groups: AE+G4/LEAE+G4, G6/LE+G6, and G7/LE+G7. Significant differences were found in the remaining groups: AE+G5/LEAE+G5, AE+G5/LEAE-H+G5, and LEAE+G5/LEAE-H+G5. The bond strength results were compared among similar published data and possible influences from different laser parameters, bonding systems, and their combined impact on the enamel surface and its adhesion properties were analyzed. CONCLUSION: Under our specific settings, additional laser conditioning after phosphoric acid etch is beneficial to one generation of bonding resin (G5). There is no significant change or detrimental effect to the other three groups (G4, G6, and G7) of bonding resins with respect to their final bond strength. The published reports of lower bond strength after additional laser conditioning may be related to thermal damage or unfavorable alteration to the enamel surface by excessive laser energy and the chemistry of bonding systems studied. These factors will affect the overall wettability and the subsequent adhesion properties of the enamel surface.

Microtensile bond strength of an etch-and-rinse adhesive to enamel and dentin after Er:YAG laser pretreatment with different pulse durations.

The purpose of this study is to evaluate microtensile bond strength (µTBS) of an etch-and-rinse adhesive to enamel and dentin after treatment with Er:YAG laser using different pulse durations. Extracted human molars were flattened to obtain enamel or dentin surfaces. The enamel specimens (E) were divided into nine groups and the dentin (D) specimens were divided into seven groups according to the surface treatments (n = 6). E-C: acid was applied according to the manufacturer's instructions and used as control, E-SSP: 120 mJ, 10 Hz, SSP (50 µs), E-SSP-A: 120 mJ,10 Hz, SSP+acid, E-VSP: 120 mJ, 10 Hz, VSP (100 µs), E-VSP-A: 120 mJ, 10 Hz, VSP+acid, E-SP: 120 mJ, 10 Hz, SP (150 µs), E-SP-A:120 mJ,10 Hz, SP+acid, E-LP:120 mJ,10 Hz, LP (300 µs), E-LP-A:120 mJ,10 Hz, LP+acid; D-C: acid was applied and used as control, D-SSP: 80 mJ, 10 Hz, SSP, D-SSP-A: 80 mJ, 10 Hz, SSP+acid, D-VSP: 80 mJ, 10 Hz, VSP, D-VSP-A: 80 mJ, 10 Hz, VSP+acid, D-SP: 80 mJ, 10 Hz, SP, D-SP-A: 80 mJ, 10 Hz, SP+acid. After application of etch-and-rinse adhesive, composite built-ups were created with a nanoceramic composite. Specimens were sectioned into serial 1-mm(2) sticks, and µTBS was measured in five sticks from each tooth randomly selected (n = 30). Failure modes were determined under a stereomicroscope. µTBS test data were analyzed by Welch-ANOVA followed by Dunnett's T3 tests and failure mode distributions were analyzed by Pearson Chi-square test (p = 0.05). µTBS was higher for enamel and dentin after additional acid etching than laser irradiation alone. E-SSP-A group exhibited the highest µTBS for enamel (p < 0.05). The D-SP-A group showed the highest value but the difference was not significant in comparison to D-C (p > 0.05). The µTBS of laser-irradiated but not acid-etched groups decreased when longer pulse durations were used. Laser treatment could enhance or impair the µTBS to enamel and dentin depending on the pulse duration used and additional acid application.

The effect of an Er,Cr:YSGG laser on the micro-shear bond strength of composite to the enamel and dentin of human permanent teeth.

The bond strength of resin composite to Er,Cr:YSGG laser-irradiated enamel and dentin has been evaluated in only a few studies. Therefore, we measured and compared the micro-shear bond strength of composite restorations to enamel and dentin using two different cavity-preparation tools and conditioning methods. One hundred and seventy-five caries-free human third molars were sectioned longitudinally into two different thicknesses and randomly assigned to seven subgroups (n = 25). Enamel groups included laser-cut without etching (LO), laser-cut and laser-etched (LL), laser-cut and acid-etched (LA), bur-cut and laser-etched (BL1), and bur-cut and acid-etched (BA1-comparison group). Dentinal groups included bur-cut and laser-etched (BL2) and bur-cut and acid-etched (BA2-comparison group). The specimens were bonded by Single Bond and Tygon tubes and were restored with Z100 composite. Failure patterns were evaluated using a stereomicroscope, and a shear bond test was performed at 0.5 mm/min. The mean shear bond strength values (MPa) for the LO, LL, LA, BL1 and BA1 enamel groups were 23.14, 23.77, 23.51, 19.30, and 28.99, respectively, whereas for the BL and BA dentinal groups, these values were 22.44 and 26.15, respectively. In enamel specimens, BA1 and LL groups presented the highest shear bond strength values, and the bur-cut and laser-etched (BL1) group showed the lowest values. In the laser-etched groups, bond strength values for bur-cut surfaces were significantly higher than those for laser-cut surfaces. Moreover, there was a significant difference between the BL2 and BA2 dentinal groups. The results of this study indicate that re-etching with acid phosphoric would be recommended if an Er,Cr:YSGG laser is used for tooth preparation or surface treatment.

Effect of Low-Level Er: YAG (2940 nm) laser irradiation on the photobiomodulation of mitogen-activated protein kinase cellular signaling pathway of rodent cementoblasts.

BACKGROUNDS: Dental avulsion due to trauma, especially in young patients, is a worldwide problem, requiring tooth replacement. Delayed replantation could cause tooth loss when the cementum is severely damaged. A small number of studies has reported that photobiomodulation (PBM) therapy using Er: YAG laser irradiation activates cellular signaling responses in different cell types, resulting in a variety of favorable biological effects. The aim of this in vitro study was to evaluate the potential biostimulatory effect of low-level Er: YAG laser irradiation on the biological responses of cultured mouse cementoblasts (OCCM-30), including the mitogen-activated protein kinases (MAPKs). METHODS: OCCM-30 cells were exposed to 2940 nm Er: YAG laser irradiation for 15 s at 0.34 W (pulse duration of 100 or 1000 µs, 17 mJ/pulse) at energy densities of 1 or 2 J/cm2. Irradiated and non-irradiated OCCM-30 cells were tested for migration (Scratch assay), proliferation (MTS assay) and functional differentiation (Alizarin Red S assay). Lumican (Lum) and Fibromodulin (Fmod) gene expression, and activation of MAPKs, were assessed by RT-PCR and Western blotting, respectively. RESULTS: Low-level Er: YAG laser irradiation at 2 J/cm2 and pulse duration of 1000 µs resulted in the highest migration rate and proliferation. Moreover, the pulse duration irradiation of 100 µs increased Lum expression. Fmod expression was increased after 1000 µs pulse duration laser stimulation. Low-level Er: YAG laser irradiation increased the mineralization of OCCM-30 cells after 7 days and activated ERK1/2, P38 and JNK signaling. CONCLUSIONS: Low-level Er: YAG laser irradiation induces OCCM-30 cell migration, proliferation and differentiation, and activates the MAPK signaling pathway.

Bactericidal effect of a Nd:YAG laser on Enterococcus faecalis at pulse durations of 15 and 25 ms in dentine depths of 500 and 1,000 µm.

The success of endodontic treatment depends on the effective elimination of microorganisms from the root canal, and lasers provide more effective disinfection than conventional treatment using rinsing solutions. The objective of this in vitro study was to determine the bactericidal effect of laser irradiation in dentine of various depths at a wavelength of 1,064 nm and pulse durations of 15 and 25 ms. A total of 90 dentine slices were cut from bovine incisors and divided into two groups (45 slices each) of thickness 500 and 1,000 µm. All were inoculated with a suspension of Enterococcus faecalis (5.07 × 10(9) bacteria/ml). Based on the clinically accepted dose (approximately 300 J/cm(2)), the following laser settings were chosen for this study: 1.75 W, 0.7 Hz for 4 s, three repetitions. The two groups were divided into two subgroups of 15 slices each to be irradiated with pulse durations of 15 and 25 ms. The remaining 15 slices per group were not irradiated to serve as a control. After irradiation, the colony-forming units (CFU) were counted and evaluated. To determine the bactericidal effect of irradiation with different pulse durations, the results in the different groups were compared statistically. For all irradiated subgroups a bactericidal effect was observed at pulse durations of 15 and 25 ms (p=0.0085 and p<0.0001). The corresponding average log kills were 0.29 (15 ms) and 0.52 (25 ms) for 500 µm and 0.15 and 0.3 for 1,000 µm, respectively. The results of this in vitro study showed that Nd:YAG laser irradiation with a pulse duration of 15 ms eliminated an average of 49% and 29% of E. faecalis at dentine depths of 500 µm and 1,000 µm, respectively, and irradiation with a pulse duration of 25 ms eliminated 70% (500 µm) and 50% (1,000 µm). However, these values are lower than those achieved with the established protocol using microsecond pulses.

Evaluation of the effects of CO2 laser on debonding of orthodontics porcelain brackets vs. the conventional method.

Debonding of ceramic brackets due to their high bond strength and low fracture toughness is one of the clinician's complications. The purpose of this study is to evaluate the effect of a laser on shear bond strength, site of debonding, and ARI index during debonding of ceramic brackets and then compare it to the conventional method used for this procedure. Thirty polycrystalline alumina (G & H Series, Germany) brackets were bonded to 30 intact extracted first and second maxillary premolars and stored in a 1% thymol solution. A chemically cured orthodontic composite resin (No-mix, Unitek, USA) was used for bonding the brackets to the enamel surface on all teeth. All brackets were positioned 4 mm from the incisal edge of the teeth with an orthodontic bracket-positioning device. Then the teeth with bonded brackets were embedded in auto-polymerized polymethylmethacrylate (2.2.3 cm) blocks using a special device to make their slots horizontally parallel. These 30 teeth were then divided into two subgroups: control or no-lased (n = 15) and super pulse CO(2) laser (n = 15). To characterize the peak of SBS in two groups, we used an Instron machine while its blade was moving at a constant speed of 1 mm/min. For evaluating the site of debonding and the adhesive remnant index (ARI index), a light microscope and the Photoshop program were used. Means and standard deviations of the SBS in two subgroups shows that in the control group, the teeth have definitely higher values in comparison to the experimental group. The results of the two groups drew no substantial differences with respect to the surface of debonding, which was mostly within the adhesive. However, observing the results of ARI presented a significant distinction between the control and experimental group. This index denoted that the debonding site in the control group was closer to the enamel adhesive interface and, consequently, the rate of enamel damage in this group would be greater. The present study shows that a CO(2) laser has the potential to replace the conventional method for debonding ceramic brackets due to less debonding force and more adhesive remnant index on the tooth surface.

The Photobiomodulation Effect of 940nm Laser Irradiation on Enterococcus faecalis in Human Root Dentin Slices of Varying Thicknesses.

Introduction: An increase in dentine thickness could result in an inadequate depth of laser energy penetration. This study aimed to evaluate the effect of a 940 nm laser on Enterococcus faecalis through varying thicknesses of human root dentin slices. Methods: Thirty-five dentin slices of root dentin with thicknesses ranging between 500 and 3000 µm were produced. Six experimental groups (500, 1000, 1500, 2000, 2500, and 3000 µm (n=5 each) were lased and the seventh, non-lased group served as the positive control with a dentine thickness of 2000 µm. The slices were inoculated with 2 µL of E. faecalis suspension of 1.5 × 108 E. faecalis cells/mL. All the lased slices were lased from the opposing side of the inoculation. A non-initiated 200 µm bare end fibre at the power of 1 W, in a continuous wave was used. Four doses of laser irradiation of 5 seconds with a side to side movement with the tip held at a 5º angle to the dentine slice were performed. The colony-forming units of E. faecalis were determined and the bacterial photobiomodulation effect analysed using one-way ANOVA with a Bonferroni and Holm post hoc test at a significance level of P > 0.05. Results: There were statistical differences between the dentin slices of 500, 1000, and 1500 µm treated with the laser compared to the positive control (P < 0.01). However, there were no statistical differences between the lased 2000 and 2500 µm slices compared to the positive control. There was significantly more photobiomodulation of the E. faecalis for the dentine slices of 3000 µm than the positive control (P < 0.01). Conclusion: Laser treatment through dentine slices of 2000 µm and thinner significantly reduced bacterial growth. The photobiomodulation effects started to occur in dentine slices thicker than 2500 µm compared to the positive control.