Efficacy of long pulse Nd:YAG laser versus fractional Er:YAG laser in the treatment of hand wrinkles

There are different modalities for hand rejuvenation. Fractional Er:YAG laser and long pulse Nd:YAG laser were introduced for treating hand wrinkles. We plan to compare fractional Er:YAG laser and long pulse Nd:YAG laser in a randomized controlled double-blind design with multiple sessions and larger sample size in comparison with previous studies. Thirty-three participants with hand wrinkles entered this study. They were randomly allocated to undergo three monthly laser treatments on each hand, one with a fractional Er:YAG laser and the other with a long pulse Nd:YAG laser. The evaluations included assessment of clinical improvement determined by two independent dermatologists not enrolled in the treatment along with measuring skin biomechanical property of hands using a sensitive biometrologic device with the assessment of cutaneous resonance running time (CRRT). Moreover, potential side effects and patients’ satisfaction have been documented at baseline, 1 month after each treatment, and 3 months after the final treatment session. Clinical evaluation revealed both modalities significantly reduce hand wrinkles (p value < 0.05), with no significant difference between two lasers. Mean CRRT values also decreased significantly after the laser treatment compared to those of the baseline in both laser groups. There was no serious persistent side effect after both laser treatments. Both fractional Er:YAG and long pulse Nd:YAG lasers show substantial clinical improvement of hand skin wrinkles with no serious side effects. However, combination treatment by these lasers along with the other modalities such as fat transfer could lead to better outcomes in hand rejuvenation. Trial registration: IRCT2016032020468N4     

Er:YAG Lasers Versus Ultrasonic and Hand Instruments in Periodontal Therapy: Clinical Parameters, Intracrevicular Micro-organism and Leukocyte Counts

Abstract Objective: The aim of this study was to compare the clinical parameters and crevicular cell population, particularly leukocyte counts, changes after initial periodontal therapy with different instruments by a chairside laboratory technique, in severe periodontitis patients. Background data: Although scaling and root planing (SRP) with hand curettes or ultrasonic scalers may alter the subgingival microbial composition and improve clinical parameters, it is known that this effect decreases as the pocket depth (PD) increases. Material and methods: Thirty systemically healthy subjects with severe chronic periodontitis were randomly assigned to three groups (n=10), and were treated either with hand curettes, ultrasonic scalers, or Er:YAG laser alone. Clinical measurements were made before and 90 days after treatment. A total of four subgingival plaque samples were collected from pockets with a PD 4-6 and ≥7?mm and were analyzed with a phase-contrast microscopy for microorganism proportions and leukocyte counts at baseline and 7 and 90 days after treatment. Results: From day 0 to day 90, clinical parameters were significantly improved in all groups (p<0.01), but there were no significant differences among groups. Laboratory assessments revealed significant differences in all groups between baseline, day 7, and day 90. However, considering changes from day 7 to day 90, hand curettes were the most successful for maintaining the levels of micro-organisms and leukocytes. Conclusions: Although Er:YAG lasers are promising in treating periodontitis, the results of this study favor finishing SRP with hand curettes. Moreover, as there is a similar tendency between micro-organism and leukocyte count changes, leukocyte counts may be used as chairside marker to evaluate the efficacy of SRP.     

Comparative efficacy of Er,Cr:YSGG and Er:YAG lasers for etching of composite for orthodontic bracket bonding

Several techniques have been proposed to obtain a durable bond, and the efficacy of these techniques is assessed by measuring parameters such as bond strength. Laser has provided a bond strength as high as that of acid etching in vitro and has simpler use with shorter clinical time compared to acid etching. This study aimed to compare the efficacy of Er:YAG and Er,Cr:YSGG lasers for etching and bonding of composite to orthodontic brackets. No previous study has evaluated the effect of these particular types of laser. A total of 70 composite blocks were randomly divided into five groups (n?=?14): group 1, etching with phosphoric acid for 20 s; group 2, Er:YAG laser irradiation with 2 W power for 10 s; group 3, Er:YAG laser with 3 W power for 10 s; group 4, Er,Cr:YSGG laser with 2 W power for 10 s; group 5, Er,Cr:YSGG laser with 3 W power for 10 s. Metal brackets were then bonded to composites, and after 5000 thermal cycles, they were subjected to shear bond strength test in a universal testing machine after 24 h of water storage. One sample of each group was evaluated under a scanning electron microscope (SEM) to assess changes in composite surface after etching. The adhesive remnant index (ARI) was calculated under a stereomicroscope. Data were statistically analyzed. The mean and standard deviation of shear bond strength were 18.65?±?3.36, 19.68?±?5.34, 21.31?±?4.03, 17.38?±?6.94, and 16.45?±?4.26 MPa in groups 1–5, respectively. The ARI scores showed that the bond failure mode in all groups was mainly mixed. The groups were not significantly different in terms of shear bond strength. Er:YAG and Er,Cr:YSGG lasers with the mentioned parameters yield optimal shear bond strength and can be used as an alternative to acid etching for bracket bond to composite.     

Nd:YAG laser as an adjunctive treatment to nonsurgical periodontal therapy

A meta-analysis was conducted to investigate whether the use of Nd:YAG laser adjunctive to scaling root planing (SRP) could provide additional benefits compared to SRP alone in patients with chronic periodontitis. The meta-analysis was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analysis) statement and the recommendations of the Cochrane Collaboration. A literature search was performed on seven databases, followed by a manual search. Weighted mean differences and 95 % confidence intervals were calculated for the clinical attachment level (CAL), probing depth (PD), and changes in plaque index (PI) and gingival crevicular fluid (GCF). Inter-study heterogeneity was assessed by the I ² test, and publication bias was analyzed by the visual inspection of the funnel plot for asymmetry, Egger’s regression test, and trim-and-fill method. All outcomes were evaluated from baseline to the end of follow-up. Significant differences in PD and GCF reduction were observed in favor of SRP?+?Nd:YAG; no significant differences were observed in CAL gain or PI change. The findings of this meta-analysis suggest that use of the Nd:YAG laser as an adjunctive therapy to conventional nonsurgical periodontal therapy could potentially provide additional benefits. However, all included studies were not at low risk of bias, and only three studies were included in the meta-analysis. As a result, the evidence is insufficient to support the effectiveness of adjunctive Nd:YAG to SRP. Future long-term well-designed parallel randomized clinical trials are required to assess the effectiveness of the adjunctive use of Nd:YAG laser. These trials should also include microbiological and adverse events analyses.     

Bond strengths of brackets bonded to enamel surfaces conditioned with femtosecond and Er:YAG laser systems

The aim of this study was to compare femtosecond and Er:YAG laser systems with regard to enamel demineralization and bracket bond strength. Human-extracted premolars were randomized to three groups (n?=?17) depending on the conditioning treatment used for the buccal surfaces: 37 % orthophosphoric acid, Er:YAG laser etching (MSP mode 120 mJ, 10 Hz, 1.2 W), and femtosecond laser etching (0.4 W, 800 nm, 90 fs/pulse, 1 kHz). Metal brackets were bonded with Transbond XT to the conditioned surfaces and light cured for 20 s. The samples were thermocycled (5000 cycles, 5–55 °C) and subjected to shear bond strength (SBS) testing using a universal testing machine. Failure types were analyzed under an optical stereomicroscope and SEM. The adhesive remnant index (ARI) was evaluated to assess residual adhesive on the enamel surface. The results revealed no significant differences in SBS between the Er:YAG laser (7.2?±?3.3 MPa) and acid etching groups (7.3?±?2.7 MPa; p?<?0.05), whereas a significant difference was observed between the femtosecond laser etching group (3.3?±?1.2 MPa) and the other two groups (p?<?0.01). ARI scores were significantly different among the three groups. The results of our study suggest that laser conditioning with an Er:YAG system results in successful etching, similar to that obtained with acid. The sole use of a femtosecond laser system may not provide an adequate bond strength at the bracket–enamel interface.     

Evaluation of the effects of Er:YAG laser,Nd:YAG laser,and two different desensitizers on dentin permeability: in vitro study

The purpose of this in vitro study was to evaluate and compare the efficacy of erbium-doped yttrium aluminum garnet (Er:YAG) laser, neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, PrevDent nano-hydroxyapatite toothpaste plus Repairing Serum Kit (PNH), and NUPRO Sensodyne Prophylaxis Paste with NovaMin (NPP) on dentin permeability reduction. Forty dentin discs obtained from bovine incisors were divided into four study groups: Er:YAG laser-treated (2940 nm; 0.2 W, 80 mJ/pulse, 3 Hz); Nd:YAG laser-treated (1064 nm; 1 W, 10 Hz); PNH-treated; and NPP-treated groups. The quantitative changes in permeability of each dentin disc were measured using a computerized fluid filtration method (CFFM) before and after desensitizer treatments. The data were analyzed using the Wilcoxon, paired-samples t, Kruskal-Wallis, and Mann-Whitney U tests. The dentin surfaces and tubules were also morphologically detected by scanning electron microscopy (SEM). In all groups, dentin permeability was significantly reduced after the desensitizer and laser treatments (p?<?0.05). Among the groups, we detected a significant difference in only when comparing the Er:YAG laser- and NPP-treated groups (p?=?0.034). SEM analysis revealed physical changes in the dentin surface in all groups. This in vitro study shows that all tested desensitizers and laser treatments reduced dentin permeability. Also, surface changes, such as complete or partial occlusion or shrinkage of dentin tubules, were observed in all groups. Although the laser groups performed best, the PNH protocol can be considered as an alternative therapeutic product. In addition, clinical and laboratory studies should be performed for this product, and their efficacy should be assessed by combined therapy with lasers.     

Nonsurgical periodontal therapy with/without diode laser modulates metabolic control of type 2 diabetics with periodontitis: a randomized clinical trial

In order to evaluate whether nonsurgical periodontal treatment with/without diode laser (DL) decontamination improves clinical parameters, the levels of IL-1β, IL-6, IL-8, intercellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) in gingival crevicular fluid and metabolic control (HbA1c) in chronic periodontitis (CP) patients with diabetes mellitus type 2 (DM2). Sixty patients with DM2 and CP were randomly assigned into two groups to receive scaling and root planing (SRP, n?=?30) or SRP followed by diode laser application (SRP?+?DL, n?=?30). Clinical periodontal and gingival crevicular fluid (GCF) parameters were assessed at baseline, 1, and 3 months after periodontal treatment. HbA1c levels were evaluated at baseline and 3 months post-therapy. Total amounts of cytokines and molecules were analyzed by ELISA. Nonsurgical periodontal treatment with/without DL appeared to improve clinical, biochemical parameters, and glycemic control in DM2 patients (BMI?<?25 kg/m²) with CP. The SRP?+?DL group provided better reductions in probing depth (PD) and clinical attachment level (CAL) parameters compared to the SRP group (P?<?0.05). Significant reductions were found in the total amounts of GCF levels of IL-1, IL-6, IL-8, ICAM, and VCAM after treatment (P?<?0.05). HbA1c levels decreased significantly at 3 months after treatment (P?<?0.05). SRP?+?DL reduced HbA1c levels more significantly compared to SRP alone (0.41 vs. 0.22 %, P?<?0.05). SRP, especially in combination with DL, shows improvement of glycemic control for DM2 patients with CP.     

A comparative SEM study between hand instrument and Er:YAG laser scaling and root planing

Scaling and root planing are one of the most commonly used procedures for the treatment of periodontal diseases. Removal of calculus using conventional hand instruments is incomplete and rather time-consuming. In search for more efficient and less difficult instrumentation, investigators have proposed lasers as alternatives or adjuncts for scaling and root planing. The aim of the present study was to compare the effectiveness of subgingival scaling and root planing with erbium: yttrium, aluminium, garnet (Er:YAG) laser and hand instrumentation in vitro. The mesial and distal surfaces of 15 periodontal loosed extracted teeth were treated randomly either by hand instrumentation or by Er:YAG laser irradiation. After choosing the “very long pulse mode” (pulse duration of about 700 μs), the output energy of 160 mJ with 920-μm beam diameter (RO7 Perio tip, Fidelis, Fotona, Slovenia) and frequency of 12 Hz were selected, both according to the best results of past studies. In addition, air water spray was used during the procedures. The morphology of the root surface was evaluated by three observers with a scanning electron microscopy in magnifications of 50× and 400×. The result of this setting showed that the rate of remained roughness on treated root surfaces in two groups of hand instruments and Er:YAG laser had a meaningful difference: The surface roughness in Er:YAG laser group was more than in hand instruments group. The present study could demonstrate the in vitro capability of the Er:YAG laser for scaling and root planing in periodontitis, although the effectiveness of this setting did not reach that achieved by hand instrumentation. It could be concluded that lower frequency and long pulse duration maybe more suitable for the micro-morphology of root surface after treatment. This theory is going to be tested with the same laser instrument in the next study.     

Adjunctive Nd:YAG laser application in chronic periodontitis: clinical,immunological, and microbiological aspects

In recent years, the use of laser radiation has been investigated as an alternative or adjunctive tool to conventional procedures employed in the treatment of periodontal disease. Various beneficial characteristics of Nd:YAG laser radiation, such as hemostatic and bactericidal effects, might lead to improved treatment outcomes. The objective of the present study was to examine the clinical, microbiological, and anti-inflammatory efficacy of Nd:YAG laser periodontal pocket irradiation as an adjunct to scaling and root planing (SRP). Thirty patients with chronic periodontitis (CP) were randomly assigned in parallel groups to receive SRP alone or SRP followed by Nd:YAG laser (λ = 1,064 nm) (SRP+NDL). Probing pocket depth (PPD), bleeding on probing (BOP), and plaque index (PI) were recorded, and samples of gingival crevicular fluid (GCF) and subgingival microbiota were taken at baseline and post-therapy (4 and 8 weeks after treatment). The laser therapy was performed 1 day after the SRP procedure. The GCF samples were analyzed for interleukin-1beta (IL-1β), tumor necrosis factor alpha (TNF-α), and total antioxidative status (TAS). Microbiological samples were cultured and analyzed for ten bacteria. No statistically significant differences were detected for clinical or microbiological variables between SRP and SRP+NDL treatments. However, levels of IL-1 β in GCF were significantly lower after SRP+NDL treatment when compared to IL-1 β levels obtained by SRP alone after 4 weeks of treatment. Levels of TNF-α were significantly lower after the SRP+NDL treatment during post-therapy. TAS of GCF increased during post-therapy after the SRP+NDL treatment. However, after SRP alone, it remained constant. In this short-term clinical study Nd:YAG laser radiation in the treatment of CP is showed to be a potential adjunct to conventional SRP.     

Efficacy of Er:YAG laser in the treatment of chronic periodontitis: systematic review and meta-analysis

Scaling root planing (SRP) has been proven efficacious as the traditional treatment approach for chronic periodontitis. However, important limitations such as difficult access in deep pockets, grooves, and furcations have led to the development of new therapeutic strategies. The erbium-doped:yttrium-aluminium-garnet (Er:YAG) laser is one of the most promising laser types for periodontal therapy. Its efficacy in radicular debris removal and root smoothing has been proven in vitro. However, the clinical effectiveness of the Er:YAG laser remains controversial. The aim of the present systematic review was to systemically assess the scientific evidence for the effectiveness of Er:YAG laser compared to SRP in the treatment of chronic periodontitis. Electronic database searches of MEDLINE, Cochrane Controlled Clinical Trial Register, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, CINAHL, Science Direct, ISI Web of Science, and SCOPUS were performed, as well as hand-searching of relevant journals through December 23, 2010. Quality assessment was made according to the CONSORT guidelines. The systematic review was performed according to the QUOROM statement and Cochrane Collaboration recommendations. Meta-analyses of the clinical attachment level gain, probing depth reduction, and changes in gingival recession were performed using weighted mean differences for continuous data with 95% confidence intervals, nested in a random effect model. No statistically significant differences were found in any of the investigated clinical parameters among the five random controlled trials (RCTs) entered into the study, indicating that there was no evidence of effectiveness. However, significant heterogeneity, a high risk of bias in three of the five included studies, and methodological shortcomings indicate that the results should be considered with caution. Future long-term, well-designed RCTs are needed to assess the scientific evidence of Er:YAG laser efficacy as an alternative treatment strategy to SRP.     

Pulsed dye laser versus Nd:YAG laser in the treatment of plantar warts: a comparative study

Plantar warts are common viral infection that are usually challenging in treatment. Conventional treatment methods are usually invasive, have low efficacy, and need long recovery periods. In this study, we compared pulsed dye laser (PDL) and neodymium yttrium aluminum garnet (Nd:YAG) lasers in the treatment of recalcitrant plantar warts. The study included 46 patients with multiple plantar warts. In each patient, lesions were divided into two groups: one treated with Nd:YAG (spot size, 7 mm; energy, 100 J/cm²; and pulse duration, 20 ms) and the other with PDL (spot size, 7 mm; energy, 8 J/cm²; and pulse duration, 0.5 ms). Laser sessions were applied every 2 weeks with maximum of six sessions. The study included 63 % males and 37 % females with a mean age of 29.6?±?7.34 years. The cure rate was 73.9 % with PDL with no significant difference (p?=?0.87) from Nd:YAG (78.3 %). The number of sessions required was more in PDL (mean, 5.05?±?0.2) compared with Nd:YAG (mean, 4.65?±?0.5) but without significant difference. Complications were significantly higher with Nd:YAG (43.5 %) compared with PDL (8.7 %). Hematoma was the most common complication recorded by Nd:YAG (28.3 %), and it was significantly higher (p?=?0.002) than PDL (2.2 %). Relapse was recorded in 8.7 % with Nd:YAG compared with 13 % in PDL with no significant difference (p?=?0.74). Our results suggested that PDL and Nd:YAG lasers are effective in the treatment of resistant plantar warts. PDL is safer and less painful but needs more sessions, while Nd:YAG is more painful and shows more complications.     

A split-face,evaluator-blind randomized study on the early effects of Q-switched Nd:YAG laser plus Er:YAG micropeel (combined therapy) versus Q-switched Nd:YAG alone in light solar lentigines in Asians

Solar lentigines are a common sign of aging in Asians, who often asked for treatment. Various lasers, including Q-switched Nd:YAG and Er:YAG, have been adopted, but the results are not always satisfactory, especially for those who are relatively light in color. Our objective was to compare the early effects as well as side effects of Q-switched Nd:YAG laser plus Er:YAG micropeel (combined therapy) with those of Q-switched Nd:YAG laser (QSNY) alone in light solar lentigines in Asians. This was a split-face, evaluator-blind, randomized controlled study. A single session of treatment was performed on Asian patients with light facial lentigines. A combined treatment with QSNY and Er:YAG micropeel was allocated to one half of the face, and QSNY alone to the other half. The response to therapy was evaluated by two independent dermatologists, with standardized photographs taken 2 weeks and 1 month after the laser treatment. Patients’ satisfaction and preference in treatment were also assessed. Fifteen patients completed the study and were analyzed. Overall, a reduction in pigment was observed with both treatment arms during the study period. The degree of pigment reduction following combined therapy and QSNY alone was similar at 2 weeks’ follow-up (P?=?0.433). However, due to the higher incidence of postinflammatory hyperpigmentation (PIH) with combined therapy (73.3 vs 40 %), the degree of pigment reduction in the combined side of the face was found significantly lower than that of the QSNY-alone side at 1-month follow-up (P?=?0.014). Although our study results show that both combined therapy and QSNY alone are capable of reducing pigmentation, QSNY alone is considered to have more favorable qualities than combined treatment for light solar lentigines in Asians.     

A randomized controlled clinical and histopathological trial comparing excisional biopsies of oral fibrous hyperplasias using CO<Subscript>2</Subscript> and Er:YAG laser

This study was conducted in order to compare clinical and histopathological outcomes for excisional biopsies when using pulsed CO₂ laser versus Er:YAG laser. Patients (n?=?32) with a fibrous hyperplasia in the buccal mucosa were randomly allocated to the CO₂ (140 Hz, 400 μs, 33 mJ) or the Er:YAG laser (35 Hz, 297 μs, 200 mJ) group. The duration of excision, intraoperative bleeding and methods to stop the bleeding, postoperative pain (VAS; ranging 0–100), the use of analgesics, and the width of the thermal damage zone (μm) were recorded and compared between the two groups. The median duration of the intervention was 209 s, and there was no significant difference between the two methods. Intraoperative bleeding occurred in 100% of the excisions with Er:YAG and 56% with CO₂ laser (p?=?0.007). The median thermal damage zone was 74.9 μm for CO₂ and 34.0 μm for Er:YAG laser (p?<?0.0001). The median VAS score on the evening after surgery was 5 for the CO₂ laser and 3 for the Er:YAG group. To excise oral soft tissue lesions, CO₂ and Er:YAG lasers are both valuable tools with a short time of intervention and postoperative low pain. More bleeding occurs with the Er:YAG than CO₂ laser, but the lower thermal effect of Er:YAG laser seems advantageous for histopathological evaluation.     

Effect of dental surface treatment with Nd:YAG and Er:YAG lasers on bond strength of resin composite to recently bleached enamel

The aim of this work is to evaluate the effect of surface treatment with Er:YAG and Nd:YAG lasers on resin composite bond strength to recently bleached enamel. In this study, 120 bovine incisors were distributed into two groups: group C: without bleaching treatment; group B: bleached with 35% hydrogen peroxide. Each group was divided into three subgroups: subgroup N: without laser treatment; subgroup Nd: irradiation with Nd:YAG laser; subgroup Er: irradiation with Er:YAG laser. The adhesive system (Adper Single Bond 2) was then applied and composite buildups were constructed with Filtek Supreme composite. The teeth were sectioned to obtain enamel-resin sticks (1 × 1 mm) and submitted to microtensile bond testing. The data were statistically analyzed by the ANOVA and Tukey tests. The bond strength values in the bleached control group (5.57 MPa) presented a significant difference in comparison to the group bleached and irradiated with Er:YAG laser (13.18 MPa) or Nd:YAG (25.67 MPa). The non-bleached control group presented mean values of 30.92 MPa, with statistical difference of all the others groups. The use of Nd:YAG and Er:YAG lasers on bleached specimens was able to improve the bond strengths of them.     

Ab-interno neodymium:YAG versus erbium:YAG laser sclerostomies in a rabbit model.

This study was undertaken to determine whether thermally-induced tissue necrosis was a factor in ab-interno contact-laser sclerostomy failure. A rabbit model was used to compare the continuous-wave Neodymium (Nd):YAG with the pulsed Erbium (Er):YAG laser with respect to such failure. Laser energy was focused into a fused-silica fiber optic (400 microns) for the Nd:YAG laser (12 W; 3 to 5 seconds), and into a single-crystal, uncladded sapphire fiber optic (250 microns) for the Er:YAG laser (7 to 8 mJ; 250 microseconds; 6 to 8 pulses). The Nd:YAG and Er:YAG lasers required from 21 to 35 J and from 42 to 64 mJ, respectively, to create the sclerostomies. Filtering blebs and intraocular pressure reduction lasted longer (log-rank test; P less than .03) and surgical complications were fewer in the Er:YAG group than in the Nd:YAG group. By creating sclerostomies with minimal thermal damage, the Er:YAG laser may offer significant clinical advantages over lasers producing larger thermal effects.     

In vitro inactivation of endodontic pathogens with Nd:YAG and Er:YAG lasers

Both Nd:YAG and Er:YAG lasers have been suggested as root canal disinfection aids. The aim of this in vitro study is to compare both wavelengths in terms of irradiation dose required for microbial inactivation, to quantify these irradiation doses and to investigate the influence of certain (laser) parameters on the antimicrobial efficacy. Agar plates containing a uniform layer of Enterococcus faecalis, Candida albicans or Propionibacterium acnes were mounted perpendicularly underneath the laser handpieces (5?mm spot). The Er:YAG laser was operated in single-pulse mode. Pulse energies of 40–400?mJ and pulse lengths of 100, 300, 600, and 1,000?μs were tested. After incubation at 37°C for 48?h, growth on the plates was scored. The pulse energy yielding complete absence of growth over the entire spot area was taken as the total inhibition threshold (TIT). TITs were determined for every species and pulse length. The Nd:YAG laser was operated with pulse trains because single pulses were ineffective. Output power was 15?W and frequency was 100?Hz. Spots were irradiated for 5–120?s. After incubation, the diameters of the inhibition zones were measured. For the Er:YAG laser, TITs varied between 100 and 210?mJ, and differed significantly between species and pulse lengths. Using Nd:YAG irradiation, TITs were around 5,300?J/cm² for C. albicans and 7,100?J/cm² for P. acnes. No inhibition was observed for E. faecalis. Er:YAG irradiation was superior to Nd:YAG in inactivating microorganisms on agar surfaces.     

Effects of different lasers on organic/inorganic ratio of radicular dentin

The aim of this study was to evaluate the chemical stability of endodontic-treated root dentin after different laser irradiations through Raman spectroscopy. Fifty maxillary canines were selected and prepared with K3 system. Roots were randomly distributed into five groups (n?=?10) according to the surface treatment: GI (water), GII (NaOCl?+?EDTA), GIII (NaOCl?+?EDTA?+?980 nm Diode laser), GIV (NaOCl?+?EDTA+ 1064 nm Nd: YAG laser) and GV (NaOCl?+?EDTA+ 2780 nm Er,Cr: YSGG laser). Lasers were applied for 20 s. Samples were bisected, and the organic and inorganic content of dentin was analyzed by Raman spectroscopy. Data were submitted to ANOVA and Tukey tests (p?<?0.05). None of the surface treatments alter the inorganic content (cts) (p?=?0.183). Roots irradiated with Er,Cr: YSGG laser had a reduced collagen content (GV-290.7?±?41.7) compared with the water-treated roots (GI-328.3?±?63.5) and those treated with NaOCl?+?EDTA (GII-333.9?±?55.8). Roots irradiated with Er,Cr: YSGG laser also showed a higher inorganic/organic ratio (GV-9.5?±?1.1) than roots treated with water (GI-7.7?±?1.5), NaOCl?+?EDTA (GII-8.0?±?1.4) and diode laser (GIII-8.2?±?1.6). Both organic and inorganic contents increased from cervical to apical thirds in all groups. None of the surface treatments were able to promote changes in the inorganic content of the root dentin; treatment with NaOCl?+?EDTA combined with Er,Cr: YSGG altered collagen.     

Efficacy and safety of fractional CO<Subscript>2</Subscript> laser versus fractional Er:YAG laser in the treatment of facial skin wrinkles

Ablative fractional lasers were introduced for treating facial rhytides. Few studies have compared fractional CO₂ and Er:YAG lasers on cutaneous photodamages by a split trial. The aim of the present study was to compare these modalities in a randomized controlled double-blind split-face design with multiple sessions and larger sample size compared to previous studies done before. Forty patients with facial wrinkles were enrolled. Patients were randomly assigned to receive three monthly treatments on each side of the face, one with a fractional CO₂ and one with a fractional Er:YAG laser. The evaluations included investigating clinical outcome determined by two independent dermatologists not enrolled in the treatment along with measuring skin biomechanical property of cheeks using a sensitive biometrologic device with the assessment of cutaneous resonance running time (CRRT). Moreover, possible side effects and patients’ satisfaction have been recorded at baseline, 1 month after each treatment, and 3 months after the last treatment session. Clinical assessment showed both modalities significantly reduce facial wrinkles (p value?<?0.05), with no appreciable difference between two lasers. Mean CRRT values also decreased significantly after the laser treatment compared to the baseline in both laser groups. There was no serious long-standing adverse effect after both laser treatments, but the discomfort was more pronounced by the participants after CO₂ laser treatment. According to the present study, both fractional CO₂ and fractional Er:YAG lasers show considerable clinical improvement of facial skin wrinkles with no serious adverse effects, but post-treatment discomfort seems to be lower with Er:YAG laser.     

In vitro bond strength of an epoxy resin-based root canal sealer to root dentin irradiated with high-power lasers and adhesive interface analyses

The aim of this study was to evaluate in vitro the influence of high-power lasers (Nd:YAG and diode 980 nm) associated with mineral coal as fotopotencializer on bond strength of an epoxy resin-based root canal sealer to root dentin, using the pushout test, and on the dentin/filling material interface, using confocal laser microscopy. For this purposes, 50 canines were instrumented with Mtwo rotary system up to #50.04 instrument and randomly assigned to five groups (n = 10): group I—control EDTAC; group II—EDTAC and Nd:YAG laser; group III—EDTAC and diode laser 980 nm; group IV—EDTAC, Nd:YAG laser and mineral coal 5 g/100 mL; and group V—EDTAC, diode laser 980 nm and mineral coal 5 g/100 mL. All data were analyzed by ANOVA (at 5% significance level) following the Kruskal-Wallis, Dunn and Tukey tests. The group I increased more bond strength of the sealer to root dentin that treated with only EDTAC 17% (17.21 ± 21.75 MPa), similar to the group II (12.21 ± 18.20 MPa) and group IV (14.92 ± 28.06 MPa), both treated with Nd:YAG laser, with the exception of group IV, which was added to mineral coal. The group V (8.75 ± 13.42 MPa) had similar results to the groups II and IV, but the same similarity were found when compared with group III (7.11 + 11.28 MPa), with lower results. Regarding the root thirds, the apical third (23.27 ± 29.21 MPa) presented a statistically higher value on bond strength than the cervical third (5.92 ± 5.33 MPa) and middle third (6.93 ± 7, 11 MPa) (p > 0.05). Group II (86.27 μm) showed the highest tags penetration values, with a statistically difference to the group III (51.57 μm), IV (36.77 μm) and V (32.37 μm) (p < 0.05). Group I (71.63 μm) was statistically similar to groups II and III (p > 0.05). Group IV had the lowest values and was statistically similarity to groups III and V (p > 0.05). It was concluded that the treatment with Nd:YAG laser provides better results than the diode 980 nm laser, except when was added mineral coal. The control and diode 980 nm laser groups presented less adhesive failures and more mists failures than the other groups. Both lasers did not interfere negatively compared to the control group.     

Comparative evaluation of the effects of Nd:YAG and Er:YAG laser in dentin hypersensitivity treatment

Dentin hypersensitivity (DH) is one of the most common complications that affect patients after periodontal therapy. So far, many investigators have successfully used different types of laser on DH treatment. The aim of this study was to evaluate the comparative effect of Nd:YAG laser and Er:YAG laser on human teeth desensitization. A group of nine patients with a total of 63 chronic hypersensitive teeth were selected. Each one of them should at least have three hypersensitive teeth. These teeth were randomly allocated into three groups. Group 1, Nd:YAG laser (1 W, 15 Hz, 60 s, two times); group 2, Er:YAG laser (100 mJ, 3 Hz, 60 s, two times); and group 3 serves as control group without any treatment. Assessment of pain was performed by a visual analysing scale (VAS) after stimulation of sensitive tooth by using the sharp tip of an explorer. This test was performed before treatment, immediately after that and at 1-, 3- and 6-month intervals after treatment by one blinded examiner. Analysis of VAS score between the three groups at the time of treatment did not show any significant difference (p = 0.506). However, by using repeated-measurement analysis of variance test, significant differences were seen in the three groups between before-treatment VAS score and after treatment (p < 0.0005). This statistically significant difference in the control group demonstrated a placebo effect. However, the effect of using Nd:YAG and Er:YAG lasers was stronger than this placebo effect, so that after removing the effect of the placebo, differences immediately after, 1, 3 and 6 months post treatment between all three groups still were statistically highly significant (p < 0.0005). Compared to the Er:YAG laser group, using Nd:YAG laser resulted in a significant reduction of VAS score at each follow-up examination (p < 0.0005). Although using Nd:YAG and Er:YAG laser in desensitization of hypersensitive teeth showed a placebo effect limited to a short time, results of this study demonstrated that both of these lasers have an acceptable therapeutic effect. The observed effects seemed to last for at least 6 months. It was concluded that Nd:YAG laser is more effective than Er:YAG laser in reduction of patients’ pain.