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In-situ 3D shape and recession measurements of ablative materials in an arc-heated wind tunnel by UV stereo-digital image correlation
摘要： In-situ three-dimensional (3D) ablation shape and recession measurements of ablative materials of hypersonic vehicles in high-temperature wind tunnel tests are essential to understand the ablation performance of these materials, which can provide necessary information for better thermal protection system (TPS) design. In this work, a novel ultraviolet stereo-digital image correlation (UV stereo-DIC) technique is proposed for in-situ measurements of 3D ablation shapes and recession in ablation tests. Specifically, a self-developed UV stereo-DIC system, combing a monochromatic UV illumination, two bandpass filters and two UV cameras, is first established. Using the UV stereo-DIC system, strong thermal radiation emitted from the heated sample and the heating device can be effectively suppressed. Natural textures formed from illuminating the rough sample surface by UV light are used as speckle patterns in stereo-correlation. In-situ 3D ablation shapes of a blunt cone subjected to arc heating were measured with a temperature range of 1000 °C to 1868 °C, and the UV stereo-DIC measurements showed good agreement with post-test measurement of the recession of the test articles. Based on the experimentally measured 3D shapes, several key parameters, such as full-field recession, dynamic recession rate, were calculated. The results demonstrate the efficacy and potential of UV stereo-DIC for 3D shape and recession measurements in ablation tests.
关键词： Recession,High temperature,UV stereo-digital image correlation,Ablation shape
更新于2025-09-23 15:22:29
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CO <sub/>2</sub> Laser De-epithelization Technique for Subepithelial Connective Tissue Graft: A Study of 21 Recessions
摘要： Background/Aim: To report cases in which we achieved sufficient width of the keratinized gingiva using a coronally advanced flap in combination with a subepithelial connective tissue graft (SCTG) obtained by the ‘CO2 laser de-epithelization technique’ (CODE). Patients and Methods: Eleven patients with 21 Miller Class I, II, and III gingival recessions had surgery. To prepare SCTG, free gingival grafts were harvested and de-epithelialized extra-orally. De-epithelialization was conducted by irradiation of CO2 laser. Postoperative examinations were performed at 12 months. Results: At 12 months, statistically highly significant root coverage was achieved in all recessions. Complete root coverage was obtained in 7 of the 21 recessions. The treatment yielded mean root coverage of 41.0%, and was associated with a mean gain of keratinized gingiva of 2.9±0.3 mm. Conclusion: The use of CODE allows harvesting grafts of excellent quality and quantity and increases the keratinization of the overlying mucosal epithelium.
关键词： Gum disease,de-epithelization,CO2 laser,gingival recession,subepithelial connective tissue graft
更新于2025-09-16 10:30:52
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Evaluation of the Effects of Er:YAG Laser for the De-Epithelialization of the Palatal Graft in the Treatment of Multiple Gingival Recessions: A Randomized Clinical Trial
摘要： Objective: The purposes of this split-mouth pilot study were to investigate the efficacy of the Er:YAG laser use for the de-epithelialization of the palatal graft in the treatment of the multiple gingival recessions using the bilaminar procedure and also to evaluate the patient-reported esthetic outcomes after 6 months. Materials and methods: Five systemically healthy participants with total 28 bilateral-multiple adjacent maxillary Miller I recessions were included. The treatment was performed with the bilaminar technique [coronally advanced flap (CAF)+de-epithelialized free gingival graft]. De-epithelialization procedure was done with scalpel (control site) or Er:YAG laser (Versawave, Hoya ConBio, San Francisco, CA; 40 hz, 50 mJ/pulse), under water irrigation, noncontact mode (*1 mm away from the target tissue) in sweeping motion with chisel-type laser (test site). Root coverage and patient-reported outcomes were evaluated at 6 months after the operations. Results: Clinical outcomes of the both treatment sites did not show any statistically significant differences except for the gingival thickness parameter. However, patient-reported outcomes regarding the esthetic appearance of the gingiva was detected in favor of the Er:YAG laser applied sites. Conclusions: Within the limits of the study, it can be concluded that both de-epithelialization techniques were highly effective at 6 months. However, Er:YAG laser-applied grafted sites revealed more uniform and esthetic gingival appearance compared with scalpel-used grafted sites.
关键词： de-epithelialization,Er:YAG laser,bilaminar technique,gingival recession
更新于2025-09-12 10:27:22
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Comparison between 940 nm Laser Diode and Topical 5 % Potassium Nitrate for Tooth Desensitization. Randomized Controlled Clinical trial
摘要： Purpose: To compare the effectiveness of two dental desensitization therapies, 940nm laser diode and potassium nitrate, in patients with dental hypersensitivity (DH) symptoms. Methods: This randomized clinical trial included 30 patients who initially underwent basic periodontal therapy and presented gingival recessions Class I and II (Miller 1985) with symptoms of DH. Subjects were randomly assigned into two groups. The first group (n = 15) received laser 940 nm application for 90 seconds on the surface of the recession and were given a tube of glycerin to be applied daily in order to avoid generating bias. Patients in the second group (n = 15) were exposed to inactive laser simulating the actual application of the laser, and they were given a desensitizing gel containing 0.5 g of potassium nitrate to be applied twice daily during 14 days. Controls were carried out at 15 minutes, 8 days, 15 days, and 4 weeks. Data obtained were filled out in an Excel table. For comparison between groups the Mann Whitney U and t student tests were used (p=0.05). Results: All patients involve in the study experienced reduction in DH (p<0.01) and differences between the two interventions performed. Conclusions: Laser and nitrate therapies were effective to manage DH after basic periodontal therapy. However, a statistically significant higher sensitivity reduction was observed in laser therapy group.
关键词： diode laser,dentinal sensitivity,periodontal disease,gingival recession,potassium nitrate
更新于2025-09-11 14:15:04