Histological Effects of Er:YAG Laser Irradiation with Snoring Handpiece in the Rat Soft Palate.

OBJECTIVE: The aim of this study was to assess the effects of laser irradiation with a novel snoring handpiece on the histological structures of the soft palate in a rat model. BACKGROUND: Snoring is a common problem and studies have shown that 20-50% of the population is affected. An apnea-hypopnea index of <5/h without daytime somnolence is documented as simple snoring. No snoring treatment should ever be attempted until a sleep study has been completed to rule out sleep apnea. METHODS: Twenty adult Wistar rats, weighing 200-250 g, were used in this study. Rats were randomized into two groups: experimental group (n = 10) and control group (n = 10). Laser energy was delivered in a horizontal direction to the surface of the soft palate of each rat in the experimental group for 2 min with an Er:YAG laser (LightWalker AT; Fotona) with snoring handpiece (PS04) in a noncontact mode (1.15 W, 2 Hz, 1.5 J/cm(2)). The animals were sacrificed after 24 h, 1 week, 3 weeks, or 5 weeks. The soft palate of each rat was removed by excisional biopsy. The specimens underwent histological examination. Contractions and fibrosis were reported as grading from 1+ to 3+, while edema and hyperemia were evaluated according to the absence (0) or presence (1) of any changes. Statistical analysis was done with the Mann-Whitney U and Spearman's rho tests. RESULT: A noticeable contraction of the soft palate occurred immediately after laser application. Inflammatory changes were observed histologically at 3 weeks postoperatively. Keratinization appeared after the procedure in both groups and decreased gradually. Statistically, there was a strong correlation among inflammation and time and also keratinization and time (p < 0.05). CONCLUSIONS: The present study indicates that Er:YAG laser irradiation with snoring handpiece (PS04) causes acute shrinkage of the mucosa. This contraction decreases gradually but is still present at the end of fifth week.

Effect of enamel laser irradiation at different pulse settings on shear bond strength of orthodontic brackets.

OBJECTIVE: To compare the effect of laser irradiation at two different pulse settings and acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel. MATERIALS AND METHODS: Thirty-six premolars were allocated to three groups (n  =  12): (1) 37% phosphoric acid etching, (2) erbium-doped yttrium aluminum garnet (Er:YAG) laser etching with medium-short pulse mode (MSP; 100 µs, 120 mj, 10 Hz, 1.2 W), and (3) Er:YAG laser etching with quantum-square pulse mode (QSP; 120 mj, 10 Hz, 1.2 W). Metallic brackets were bonded with Transbond XT. After photopolymerization, the samples were subjected to 5000 thermal cycles and debonded with a universal testing machine, and the SBS values were recorded. Surface morphology was evaluated with profilometric examination, scanning electron microscopy, and atomic force microscopy. The adhesive remnant index (ARI) was evaluated to assess the remaining adhesive. RESULTS: The results of SBS testing were analyzed by one-way analysis of variance and Tukey honestly significant diffference tests. The mean SBS values of QSP and MSP laser groups were 11.80 ± 2.7 MPa and 10.10 ± 4.5 MPa, respectively, and the QSP group demonstrated significantly higher SBS (P < .01) than that of the acid-etched group (6.6 ± 2.4 MPa). No significant difference was observed between the SBS values of the two laser groups (P < .05). The difference between the ARI scores of the laser groups and the acid-etched group was statistically significant (P < .05). CONCLUSION: Laser etching at MSP and QSP modes present successful alternatives to acid etching; however, long-term clinical studies are required to verify clinical success.