Background and aim: Physical and chemical composition of dentin is subject to modification when irradiated with Er:YAG laser. Temperature rise causes water evaporation and micro-mechanical ablation of dentin. The misuse of laser parameters could affect negatively dentin collagen fibers leading to failure in bonded composite restorations. The aim of this in vitro study was to evaluate the effect of Er:YAG laser radiation at different levels of energy on the morphology of thermally affected dentin layer. Materials and methods: Forty-eight freshly extracted human third molars were randomly divided into six groups (n = 8). In all groups, except for the control groups, dentin was subject to irradiation with H02 handpiece Er:YAG laser in non-contact mode (SSP mode = 50 μs; 10 Hz; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min) with the following levels of energy (40, 60, 80, 100, and 120 mJ) respectively. Teeth were sliced longitudinally. Photo-ablated cavities were observed. The cavity depth and dentin fiber collagen deterioration were measured. Results: Laser irradiation increased the depth of dentinal crater from 46.57 μm to 178.2 μm, when energy level increased from 40 mJ to 120 mJ. A superficial black layer, representing dentinal affected collagen fibers, was present in all groups except for control group. When comparing the thickness of the black layer, there was no significant difference between groups. It increased at 40 mJ to 28.17 μm then decreased to 15.19 μm at 60 mJ and then increased again for 80 mJ to 19.93 μm, 100 mJ to 22.87 μm and 120 mJ to 28.53 μm. Only one group (60 mJ) showed low values and significant difference as compared to the other irradiated groups, when multiple comparisons tests (ANOVA) were made using Newman-Keuls test. Conclusions: Dentin organic matrix presented the minimum alteration when Er:YAG laser is used specifically at an appropriate level of energy (60 mJ).
Background and aims: Physiologic gingival pigmentation (PGP) is the most common type of gingival pigmentation causing esthetic concerns particularly in gummy smile patients. Laser therapy is an effective and noninvasive treatment modality for such patients. This study aimed to evaluate the efficacy of diode laser for treatment of PGP Subjects and methods: This quasi-experimental study (one-group pretest-post-test design) was conducted on 20 patients complaining of gingival melanin pigmentation. The gingiva of the anterior segment of the arch was ablated with 810 nm diode laser until the entire visible pigmentation was removed. Clinical observations for the intensity of pigmentation were made at baseline, one month and three months, postoperatively. Data were analyzed using SPSS and Friedman test. Results: Preoperatively, the mean score of gingival melanin pigmentation in the maxilla and mandible was 2.95. At one month postoperatively, the mean scores of the maxilla and mandible were 1.53 and 1.55, respectively. After three months, the mean rank of scores of the maxilla and mandible was 1.53 and 1.50, respectively. The difference between the pre- and postoperative mean scores was statistically significant (P < 0.001). Conclusion: Diode laser therapy is an effective and minimally invasive modality for gingival depigmentation. But further investigations with long-term follow ups are warranted in this respect.
Background and Aim: An important surgical goal is to provide a first intention wound healing without trauma produced by sutures and for this aim in the past several methods have been tested. The aim of this ex vivo preliminary study was to demonstrate the capacity of a 1070 nm pulsed fiber laser to treat the dental fractures by enamel and dentine melting with the apposition of hydroxyapatite nanoparticles as filler. Methods: Out of thirty freshly-extracted human third molars, decay-free, twenty-four cylinders of 5 mm thickness were obtained to perform the test. The device used was a 1070 nm Yb-doped pulsed fiber laser: this source has a maximum average output power of 20 W and a fixed pulse duration of 100 ns, while the repetition rate ranges from 20 kHz to 100 kHz. The samples were divided in three groups (a, b, c) of eight teeth and each specimen, with the two portions strictly placed side by side, was put inside the box and irradiated three times, the first and the second at 30 kW and the last at 10 kW peak power (average powers of 60 and 20 W). The repetition rate was maintained at 20 kHz for all the tests as well as the speed of the beam at 10 mm/sec. The samples of the group a were irradiated without apposition, in the group b nanoparticles (< 200 nm) of hydroxyapatite were put in the gap between the two portions while in the group c, a powder of hydroxyapatite was employed. Results: Only the specimens of the group b showed a real process of welding of the two parts, while specimens of groups a and c did not reach a complete welding process. Conclusions: This ex vivo preliminary study, based on the enamel and dentine welding obtained by a 1070 nm pulsed fiber laser associated to the hydroxyapatite nanoparticles, may represent a new and original approach for the treatment of the fractured teeth, even if further studies will be necessary to confirm these results.
Background and aims: Data are limited about the effect of ceramic primers on the bond of zirconia to restorative resin composite. The aim of this study was to assess the effect of different surface treatments and two ceramic primers on shear bond strength (SBS) of zirconia to restorative resin composite. Materials and methods: 100 samples of zirconium ceramic blocks were randomly divided into 5 groups (n = 20) and received the following surface treatments:Type of surface preparation significantly affected the bond strength. a) Control group b) AL2O3 abrasion c) Nd:YAG laser d) Er:YAG laser e) Bur preparation Next, each group was divided into two subgroups of 20. In ten out of 20 specimens in each group, monobond plus and Tetric ceram composite resin were applied on the surface. ZPrime Plus and Elite composite were applied on the surfaces of the remaining 10 specimens in each group. Samples were then subjected to shear bond strength test in a universal testing machine until fracture. The mean SBS were calculated and statistically analyzed by two-way ANOVA and T-Test. P < 0.05 was considered statistically significant. Results: In ZPrime plus subgroups, diamond bur yielded the highest bond strength. Laser groups showed no significant difference with the control group. In monobond plus subgroups, SBS of air abrasion and diamond bur subgroups was highest and Nd:YAG laser showed the lowest SBS. The lowest bond strength belonged to the Nd:YAG laser subgroup of monobond plus group. Conclusions: Type of surface preparation significantly affected the bond strength.
Background and aims: This study was done to compare the antibacterial effect of Photodynamic therapy (PDT) on streptococcus mutans (S. mutans) using two different light sources and photosensitizers (PS). Materials and methods: Five groups were studied in this research:no light and no toluidine blue ortho (TBO) as PS for control group, irradiation only (CO2 laser or Nd:YAG laser), and irradiation with PS (CO2 laser and TBO or Nd:YAG laser and TBO). Standard suspensions of S. mutans, based on the type of group, were used in different PDTs. Bacterial suspension from each treatment was subcultured onto the surface of Mueller-Hinton agar plates, and bacterial growth was assessed. The results were analyzed by analysis of variance (ANOVA). Results: There was a statistically significant reduction in the viability of S. mutans in TBO with CO2 laser and TBO with Nd:YAG laser groups (p value < 0.05). However, there was no significant difference between control and groups treated with lasers only. The highest number of the colonies of S. mutans in treated groups was observed in CO2laser irradiation only and the lowest number was seen in CO2 laser with TBO. In the groups irradiated alone (without TBO), no significant reduction of colonies was observed. There was no significant difference between the experimental groups. Conclusions: The colonies of S. mutans were susceptible to either CO2 laser or Nd:YAG laser in the presence of TBO with no significant difference. So these lasers with this photosensitizer may be useful in prevention of dental caries and antimicrobial treatment protocols.
Background and aims: Adhesion durability of resin adhesives with Er,Cr:YSGG laser irradiated-enamel has been rarely investigated in the literature. Thus, the present study evaluated the influence of long-term water storage (12-month) on resin bond strength with the enamel irradiated with Er,Cr:YSGG laser irradiation deployed different settings. Materials and methods: The flattened enamel samples of 35 bovine teeth, which were embedded into acrylic blocks, were randomly divided into 7 groups (n = 5), according to surface treatments using Er,Cr:YSGG laser with different parameters 6 W/20 Hz, 6 W/35 Hz, 6 W/50 Hz, 3 W/20 Hz, 3 W/35 Hz, 3 W/50 Hz or no laser treatment (Bur-treating as a control). Adper Single Bond 2 was applied to the prepared enamel and the composites were placed and cured. Resin-enamel sticks with an approximate cross-sectional area of 0.8 mm2 were obtained, and microtensile bond strength (μTBS) tests were performed at 24-hour and 12-month of water storage after bonding. The μTBS data were analyzed with twoway ANOVA and Tukey tests (p < 0.05). Results : 24-hour water storage after bonding, the μTBS to laser-irradiated enamel in the 6W/ 20 Hz group was significantly lower than those of bur-treated. However, 3 W/50 Hz showed significantly higher μTBS than those of bur-treated. Two-way ANOVA revealed that 12-month water storage did not influenced μTBS. Conclusions: It may be concluded that, initial bond strength to Er,Cr:YSGG laser irradiated-enamel might be significantly influenced by power and pulse frequency settings. However, resin bonding to laser-irradiated enamel was stable over 12-month water storage regardless of tested laser parameters.
Background: The effects of Low Level Light Therapy (LLLT) on cellular function arise predominantly from stimulation of ATP production and reduction of oxidative stress. These effects are dose dependent and a function of beam irradiance and irradiation time. Human sperm motility has been shown to increase with LLLT irradiation. The objective of this study was to investigate the effects of laser and Light Emitting Diode (LED) LLLT photobiomodulation on human spermatozoa motility and DNA integrity. Methods: An in-vitro controlled trial was performed within an IVF clinic laboratory using three human semen specimens, one fresh and two frozen. Sperm were exposed to light from a GaAlAs single laser (810 nm 200 mW) and an LED cluster (660 nm and 850 nm total power 2 W) for various irradiation times. Sperm motility for the test and control aliquots was assessed using a SQA-IIB analyser, but fertilizing ability was not. Sperm chromatin integrity was tested using the Sperm Chromatin Structure Assay. Results: The Sperm Motility Index and Total Functional Sperm Count increased up to four fold compared to controls with inhibitory effects observed at higher doses (longer irradiation times). The maximum effect varied with irradiance and irradiation time and whether the sample was fresh or frozen.. Discussion: Human sperm motility is modified by exposure to LLLT and this motility modification is dependent upon beam irradiance and irradiation time as well as the condition of the sample. A higher stimulatory dose provides a rapid increase in motility that is short in duration, while a lower stimulatory dose provides a slower increase in motility. An inhibitory does causes reduced motility. Future research could consider animal models, such as the mouse, to test fertilization capacity and the safety of resulting fetuses.
Background: Hemorrhoids are a common anorectal condition with a major medical and socioeconomic impact. Owing to the high incidence of symptomatic hemorrhoids in the adult population together with the risk of complications of traditional surgery, researchers are seeking less invasive methods of hemorrhoidal treatment. The aim of this study was to present our experience with the mini-invasive Doppler guided hemorrhoidal laser procedure (HeLP) in symptomatic 2nd and 3rd degree hemorrhoids with absent or minimal mucosal prolapse. Methods: The cohort included 62 patients with symptomatic hemorrhoids who underwent the HeLP at a tertiary medical center in 2014-2016. Data were collected on clinical and perioperative characteristics and outcome. Findings were compared between patients with second- and third-degree hemorrhoids. Results: The cohort included 41 male and 21 female patients of mean age 41.5 years. Fifty-one had bleeding and 11 had hemorrhoidal syndrome. Mean operative time was 16.6 ± 3.7 minutes. A total of 8-12 arterial branches were treated. Patients were discharged home within a mean of 91.95 ± 20.48 minutes and allowed to resume normal activities. Compared to patients with second-degree hemorrhoids, patients with third-degree hemorrhoids had a significantly higher rate of recto-anal repair (18.2% vs 0, p < 0.05), intraoperative bleeding (11.3% vs 5%, p < 0.05), and thrombus formation in the hemorrhoids (11.3 % vs 0, p < 0.01). At the six-month follow-up, no complications were reported, and there was significant improvement in symptoms. Using the visual analog scale, no pain was reported by 82.3% of patients at one week after surgery and 95.2% of patients at one month after surgery. Conclusion: Patients with hemorrhoids treated with Doppler-guided laser had an excellent outcome in terms of resolution of symptoms and postoperative pain. Only Minor short-term complications were noted. Doppler-guided laser seems to be an effective and painless technique for the treatment of symptomatic second- to third grade hemorrhoids with minimal mucosal prolapse.