YAG Laser Technique Research Articles

Nucleation kinetics, growth and characterization of sodium tetraborate decahydrate – second harmonic generation in centrosymmetric crystal

Sodium tetraborate decahydrate single crystals were grown from aqueous solution by slow cooling technique. Nucleation and growth kinetics give valuable information about the crystal growth process, which can be utilized in the growth of large size crystals. Attempt are made to study the nucleation parameters such as solubility, induction period, interfacial tension, Gibbs critical free energy, radius of critical nuclei. The crystal possess positive temperature coefficient of solubility. XRD analysis shows that the crystal crystallizes in monoclinic system with space group C2/c. Thermal stability of the crystal was analyzed by TGA/DTG. From optical studies band gap of the material was found to be 5.64 eV. The existence of SHG was confirmed by Q-switched Nd:YAG laser technique.

Investigations on the nucleation kinetics of γ-glycine single crystal

Single crystals of γ-glycine were grown by slow evaporation technique. The crystalline system was confirmed by single crystal X-ray diffraction analysis. The optical absorption study has shown that the grown crystal possesses lower cut-off wavelength. Solubility and metastable zone width were estimated for different temperatures. The induction period of title compound was determined by varying the temperature and concentration. Nucleation parameters such as Gibbs volume free energy change (ΔGv), interfacial tension (γ), critical free energy change of the nucleus (ΔG⁎), nucleation rate (J), number of molecules in the critical nucleus (i⁎) have been calculated for the aqueous solution grown γ-glycine single crystals. The second harmonic generation (SHG) of γ-glycine was confirmed by Q-switched Nd:YAG laser technique.

Esthetic treatment of gingival hyperpigmentation with Nd:YAG laser or scalpel technique: a 6-month RCT of patient and professional assessment

This double-masked, randomized controlled trial with a split-mouth design aimed to compare patient- and professional-centered outcomes using different therapeutic approaches-neodymium-yttrium aluminum garnet (Nd:YAG) laser or scalpel technique-for gingival depigmentation. Patients presenting bilateral melanin gingival hyperpigmentation and who requested cosmetic therapy were recruited. Contralateral quadrants were randomly assigned to receive Nd:YAG laser (settings: 6W, 60mJ/pulse, and 100Hz) or scalpel technique. Patient morbidity experienced at intratherapy and during the first postoperative week was evaluated. In addition, after 6months, the cosmetic results achieved for the different therapeutic approaches were evaluated by patients and professionals. The chair time of each technique was also calculated. Patient-oriented outcomes concerning intratherapy morbidity did not demonstrate any differences between groups (p > 0.05), although a higher extent of discomfort/pain was experienced in the side treated by the scalpel technique compared to the Nd:YAG laser procedure during the first posttherapy week (p < 0.05). Regarding to cosmetic outcomes, no differences between techniques were observed for patient and professionals (p > 0.05). Significantly higher chair time was required for the scalpel technique than for the Nd:YAG laser therapy (p < 0.05). The Nd:YAG laser or the scalpel technique may be successfully used for the treatment of melanin gingival hyperpigmentation. However, the use of the Nd:YAG laser has presented advantages in terms of less discomfort/pain during the posttherapy period and a reduction of treatment chair time.

Long-term effectiveness of four pulpotomy techniques: 3-year randomised controlled trial

A pulpotomy is the therapy for management of pulp exposures due to caries in symptom-free primary molars. The aim was to longitudinally compare the relative effectiveness of the Er:YAG laser, calcium hydroxide and ferric sulphate techniques with dilute formocresol in retaining symptom-free molars. Two hundred primary molars in 107 healthy children were included and randomly allocated to one technique. The treated teeth were blindly reevaluated after 6, 12, 18, 24 and 36 months. Descriptive data analysis and logistic regression analysis accounting for multiple observations per patient by generalised estimating equation were used. Additionally, various influences including tooth type, upper and lower jaws, type of anaesthesia, operator and the final restoration on treatment success were evaluated (Wald chi-square test). After 36 months, the following total (considering clinical and clinically symptom-free radiographic failures) and clinical success rates were determined (in percent): Formocresol 72 (92), laser 73 (89), calcium hydroxide 46 (75), ferric sulphate 76 (97). No significant differences were detected between formocresol and any other technique after 36 months. However, the odds ratio of failure appeared to be three times higher for calcium hydroxide than for formocresol. No significant differences in total success rates were seen regarding the aforementioned influencing clinical parameters. The correct diagnosis of the pulpal status, bleeding control and the specific technique are highly important for long-term success of pulpotomies in primary molars. According to the presented long-term data, pulpotomies using ferric sulphate revealed the best treatment outcome among the used techniques, while calcium hydroxide resulted in the lowest success rates after 3 years. Therefore, we can recommend ferric sulphate for easy and successful treatment of primary molars with caries-exposed pulps.

Lipoma treatment with a subdermal Nd:YAG laser technique

Lipoma is the most common benign mesenchymal tumor composed of mature fat cells. The standard treatment for lipoma is excision. Many treatments have been described in order to minimize the scars produced by surgical excision. The treatment of lipoma using a subdermal laser produces an effective disruption of fat cells and results in a small scar. To evaluate the efficacy of subcutaneous intralesional application of a pulsed Nd:YAG laser as an option for the treatment of lipoma. From January 2001 to November 2007, 20 patients (11 women and nine men) with lipomas were treated using a subdermal, pulsed, 1064-nm Nd:YAG laser. After laser treatment, the oily solution, the product of laser action, was removed with a 2-mm cannula using a negative pressure of 350 mmHg. Histology and cytology of the treated tissue were used to analyze the effects of the laser on the fat cells. Ultrasound was performed in some subjects before and after laser treatment. Subdermal lipoma treatment using a 1064-nm Nd:YAG laser resulted in complete or almost complete removal of the tumor in 100% of patients. Four partial relapses were observed that were treated successfully by the same procedure. Adverse effects were mild and temporary. The combination of a 1064-nm Nd:YAG laser and removal of the cell debris by a suction cannula presented an effective therapeutic option for patients with lipoma. The treatment of lipoma using a 1064-nm Nd:YAG laser is a minor invasive procedure which does not result in large scars. Laser treatment is an effective and safe option for cellular disruption.

Therapy of peri‐implantitis: a systematic review

The objective of this study was to provide a systematic review of randomized controlled and/or comparative clinical trials published in the international peer-reviewed literature in the English language, up to and including July 2007, concerning the efficacy of all treatment modalities implemented for the therapy of peri-implantitis. PubMed and The Cochrane Library databases were searched electronically and numerous journals were examined manually. In the first phase of selection, the titles and abstracts, and in the second phase, complete papers were screened independently and in duplicate by three reviewers (S. K., I. K. K. and M. T.). The search yielded 1304 possibly relevant titles and abstracts. After the first phase of selection, 13 publications were singled out for a rigorous evaluation. Following the second phase, five studies were selected. The selected studies are too limited in number and exhibit small sample sizes and short follow-up periods. Therefore, there is a definite need for more well-designed, preferably longitudinal, randomized controlled clinical trials. Within the limitations of the selected studies, mechanical debridement combined with antiseptic/antibiotic therapy, the Er:YAG laser or regenerative techniques may be used for treating peri-implantitis, but the indications for each of these techniques have not been delineated clearly.

Evaluation of Patient Perceptions of Frenectomy: A Comparison of Nd:YAG Laser and Conventional Techniques

The aim of the randomized controlled clinical trial described here was to determine the anxiety levels of patients prior to frenectomy using the Nd:YAG laser and conventional technique, and to compare the effects of these two methods on the degree of postoperative pain, discomfort, and functional complications (eating and speech). Forty patients with mucogingival problems due to labial frenums (both maxillary and mandibular) were included in the study. Ratings of preoperative fear and postoperative pain and functional complications for each patient were recorded using a visual analog scale at 3 h, 1 d, and 1 wk post-surgery. The results indicated that patients treated with the Nd:YAG laser had less postoperative pain and fewer functional complications (p < 0.05). The results suggest that in the population studied, Nd:YAG laser treatment of soft tissue disorders provides better patient perceptions of success than those seen with conventional surgery.

Effectiveness of 4 Pulpotomy Techniques—Randomized Controlled Trial

Pulpotomy is the accepted therapy for the management of cariously exposed pulps in symptom-free primary molars; however, evidence is lacking about the most appropriate technique. The aim of this study was to compare the relative effectiveness of the Er:YAG laser, calcium hydroxide, and ferric sulfate techniques with that of dilute formocresol in retaining such molars symptom-free. Two hundred primary molars in 107 healthy children were included and randomly allocated to one of the techniques. The treated teeth were blindly re-evaluated after 6, 12, 18, and 24 months. Descriptive data analysis and logistic regression analysis, accounting for each patient's effect by a generalized estimating equation (GEE), were used. After 24 months, the following total and clinical success rates were determined (%): formocresol 85 (96), laser 78 (93), calcium hydroxide 53 (87), and ferric sulfate 86 (100). Only calcium hydroxide performed significantly worse than formocresol (p = 0.001, odds ratio = 5.6, 95% confidence interval 2.0-15.5). In conclusion, calcium hydroxide is less appropriate for pulpotomies than is formocresol.

Remodelage et photoréjuvénation

Resurfacing by CO 2 or Er:YAG laser techniques in the treatment of facial rhytids has traditionally involved ablative methods with, however, associated complications and limitations due to the epidermis “sacrifice”. Recently, rhytid improvement and dermal remodelling have been observed, with the utilization of non-ablative approaches. The underlying principle of non-ablative laser remodelling is to induce a controlled injury to the collagen in the dermis, while completely sparing the epidermis from damage. As dermal collagen heals and remodels under an undamaged outer layer, the skin tightens and smoothes, thus improving it’s appearance. Two classes of lasers are used for non-ablative laser remodelling : i) visible light lasers, including green and yellow light lasers adapted or modified from their original use as treatments for vascular lesions. 532nm (green) and 585nm (yellow) light are strongly absorbed by oxyhemoglobin and melanin in the epidermis and upper dermis. The heating effect in these skin layers triggers the release of various growth factors that stimulate collagen remodelling and tightening. ii) infrared lasers, emitting at 980nm, 1320nm, 1450nm and 1540nm produce invisible light that is absorbed by primarily by water, which heats the superficial layers of the skin. These lasers use contact or non-contact skin cooling to limit the heating effect to the dermis, creating a controlled injury to the dermal collagen, with subsequent remodelling and tightening. More recently, non-ablative photorejuvenation with intense pulsed light (IPL) has been introduced. Several clinical studies on non-ablative lasers, using objective evaluations (silicone imprints, cutometer, ultrasound imaging) have clearly demonstrated a progressive improvement over months. Histological examinations of the treated areas have clearly showed a superficial dermal band of well organized elastin and collagen fibres replacing pre-treatment elastic tissue. This improvement of the skin was not associated with any adverse effects. Concerning intense pulsed light, only a few clinical studies have reported varied clinical results with non-ablative photorejuvenation.

Wedge turbinectomy: a new combined photocoagulative Nd:YAG laser technique.

To demonstrate that Nd:YAG laser photocoagulation using a combination of interstitial and contact approaches in the surgical treatment of inferior turbinate hypertrophy yields improved results in terms of postoperative nasal patency, complications, and relapse. A group of 121 patients with symptoms of nasal obstruction due to hypertrophied inferior turbinates were treated between January 1994 and December 1997 at the Otolaryngology-Head and Neck Surgery Unit of the Main Military Hospital of Rome using the wedge turbinectomy, a new endonasal laser technique. This is a combined photocoagulative procedure performed under local anesthesia. In the first surgical step we perform interstitial photocoagulation using Nd:YAG laser and in the second step we use a contact approach, making two strips of photocoagulated mucosa running side by side from the tail to the head of turbinate. At 1-year follow-up, the complication rate in all our patients treated with this laser technique was very low and we achieved a steady improvement in nasal patency in 104 patients (85.9%). The relapse rate was approximately 14%, but we observed that 65% of the patients who experienced long-term failure were affected by allergic rhinitis. An accurate preoperative evaluation of the cause of the turbinate hypertrophy is fundamental to achieving better results after laser turbinectomy and reducing the risk of relapse.

Treatment of Fibrinous Pupillary Membrane Occlusion Following Cataract Surgery with Microruptor Laser

A 79-year-old female with rheumatoid arthritis suffered from severe induced iritis with dense fibrinous pupillary membrane occlusion and high intraocular pressure (57 mmHg) following cataract surgery. We used a Nd:YAG laser technique to dissect and move the dense pupillary membrane away and avoid invasive surgical procedures. Postoperatively, we recorded IOP 14 mmHg and visual acuity 20/30.

Effect of a modified Nd:YAG laser technique on neuroma formation: An experimental study in rat sciatic nerve.

Traumatic transection of a peripheral nerve is inherently associated with the development of neuroma at the end of the proximal stump, often leading to therapy-resistant pain. This study was designed to evaluate whether the neodymium:yttrium aluminum garnet (Nd:YAG) laser could prevent neuroma formation after neurectomy. The sciatic nerves of 14 rats were diffuse coagulated by defocused Nd:YAG laser (12 W power), and subsequently transected with additional focused laser energy. The control group consisted of contralateral nerves transected by microscissors. The nerves were reexposed at different time intervals up to 9 weeks after surgery, and evaluation consisted of macroscopy, and light and transmission electron microscopy. True neuroma formation could not be observed after laser transection, and only five nerves formed a neuromatous bulb, with minimal adhesions to surrounding tissue. Microscissor transection resulted in widespread amputation neuromas, consisting of regenerating axons and connective tissue, and nervous tissue regenerating into surrounding tissue. Laser-transected nerves showed degenerative changes of the axons and myelin, while proliferation of Schwann cells could not be observed. No outgrowth of axons could be observed outside the coagulated proximal stump. An epi/perineurial layer was present, covering the nerve stumps. Microscissor-transected nerves showed proliferation of fibroblasts and Schwann cells, forming minifascicles, and vigorous outgrowth of axons into the tissue and even into the distal nerve stump. Within the limitations of this study it is concluded that the formation of amputation neuromas is suppressed by Nd:YAG laser application by thermal coagulation of the nerve and suppression of Schwann-cell proliferation.

Endoscopic evaluation and management of the lacrimal sump syndrome.

Failed dacryocystorhinostomy caused by the presence of residual lacrimal sac has been termed the "lacrimal sump syndrome." Epiphora occurs when tears collect in this residual pouch and lacrimal drainage is delayed. Irrigation into the nose may seem normal. This condition can be easily diagnosed with nasal endoscopy and has a characteristic radiologic appearance. Six patients with failed dacryocystorhinostomy caused by lacrimal sump syndrome were successfully treated with an endoscopic contact Nd:YAG laser technique. Endoscopic dacryocystorhinostomy using the contact Nd:YAG laser is an effective method for treating patients who have persistent epiphora or dacryocystitis after failed dacryocystorhinostomy.

Effects of Er:YAG laser trabecular ablation on outflow facility in cadaver porcine eyes.

Mid-infrared laser technology opens new perspectives in experimental glaucoma surgery. The aim of this study was to establish the effectiveness of Er:YAG laser photoablation of the trabecular meshwork in increasing outflow facility in cadaver porcine eyes. Eye cups of 20 freshly enucleated cadaver porcine eyes were fixed in an anterior segment perfusion system, measuring outflow facility under constant pressure conditions (7-13 mmHg) over a period of 45 min. Trabecular ablation was performed using a pulsed Er:YAG (2.94 microns) laser. Radiation was delivered in a single 4-mJ pulse of 200 microseconds duration by means of an articulated zirconium fluoride optical fibre and a 320-microns quartz-fibre tip. Er:YAG laser treatment yielded reproducible ablation areas confined to the trabecular meshwork, with a diameter corresponding to that of the fibre tip. Collateral thermal damage extended up to a depth of 30 microns. Outflow facility measurements revealed an increase (mean +/- SD) from 0.128 +/- 0.041 microliter min-1 mmHg-1 in control eyes (n = 11) to 0.308 +/- 0.093 microliter min-1 mmHg-1 in treated ones (n = 9). Application of the photoablative Er:YAG laser technique in non-fistulating trabecular surgery produces patent trabecular perforation with minimal collateral tissue damage and effects a significant reduction (79%) in outflow resistance.

A comparison of endometrial ablation using the Nd:YAG laser or electrosurgical techniques

Study Objective. To compare the results of endometrial ablations performed either with the neodymium:yttriumaluminum-garnet (Nd:YAG) laser or electrosurgically. Study Design. Retrospective study, with 4-year follow-up of 82 of 98 patients. Setting. Gynecology departments of teaching, community, and proprietary hospitals. Patients. One hundred sixty-six women requiring surgical treatment for menorrhagia between March 1986 and October 1992. Interventions. Fifty-eight women were treated with a Nd:YAG laser, 11 with a rollerball electrode, and 97 with a wire loop electrode. Concomitant resection of submucous leiomyomata was performed in 54 (32.5%) of the patients. Measurements and Main Results. The mean operating times, complication rates, mean volume of fluid absorption, concomitant surgery, morbidity, duration of hospital stay, and results of laser and electrosurgical endometrial ablations were similar. Thirty-nine women (69.9%) undergoing laser endometrial ablation became amenorrhetion became amenorrheic, and 10 (90.9%) had satisfactory results. Sixty-one women (70.9%) who underwent wire loop resection became amenorrheic, with 83 (96.5%) attaining satisfactory results. Four years postoperatively, 85.4% of the patients continued to have statisfactory results. Conclusion. Laser and electrosurgical endometrial ablations are similarly effective treatment for patients suffering from chronic menorrhagia. This preliminary study should be followed by a randomized, controlled, prospective study to evaluate the two techniques more fully.

Endoscopic Diagnosis and Treatment of Early Gastric Cancer

Endoscopic diagnosis and treatment for early carcinoma of the stomach is discussed. Endoscopic ultrasonography (EUS) for diagnosing the depth of cancer invasion is investigated. Accuracy rate was 79% for 268 lesions. Mucosal cancer diagnosed by EUS was correctly determined in 91%. Endoscopic treatment by YAG laser irradiation and mucosal resection were evaluated by pretreatment and posttreatment EUS examination. With the incorporation of EUS for staging and the use of mucosal resection and YAG laser techniques, initial results of endoscopic curative therapy for early gastric cancer appear promising.

Renal Function after Partial Nephrectomy with the Nd‐YAG Laser Experimental Study in Piglets

Twelve partial nephrectomies were performed in 12 piglets using either the combination (contact and non-contact) Nd:YAG laser technique or a steel scalpel. Additional haemostasis was attempted with ligatures. The renal artery was not clamped and renal cooling was not attempted. Total nephrectomy was performed on the contralateral side. Serum creatinine and urea levels were measured, and 99mTc-DTPA renography was performed pre-operatively and 1 and 2 weeks post-operatively. One week post-operatively the mean serum creatinine level was 35% higher than the pre-operative level in the laser group and 30% higher in the steel scalpel group. Two weeks post-operatively the respective differences were 34 and 24%. The mean urea level 1 week after operation was 50% higher than the pre-operative level in the laser group and 17% higher in the steel scalpel group. Two weeks post-operatively the respective differences were 38% in the laser group and 20% in the steel scalpel group. The mean DTPA disappearance rate was 34% lower 1 week after operation in the laser group and 23% lower in the steel scalpel group when compared with the preoperative state. Two weeks post-operatively the respective changes were 48 and 25%. These data indicate that there is no significant difference in renal function when the Nd: YAG combination laser technique is used in partial nephrectomy as compared with the steel scapel.

Efficacy and Complications of the ND:YAG Laser in Partial Nephrectomy: Experimental Study in Piglets

Twenty-four partial nephrectomies were performed in 18 piglets using either the combination Nd:YAG laser technique (contact and noncontact) or a steel scalpel. Additional haemostasis was attempted with ligatures. Blood loss, operation time, and number of ligatures were compared in the two treatment groups. Twelve piglets had a two-week follow-up. The mean blood loss with the laser was 72 +/- 10 g and 83 +/- 13 g with the steel scalpel (no significant difference). The resection time until complete haemostasis was 9.8 +/- 0.9 min with the laser and 14.3 +/- 1.3 min with the steel scalpel (p = 0.0076). The number of ligatures needed for complete haemostasis was 2.8 +/- 0.4 with the laser and 7.5 +/- 1.0 with the steel scalpel (p = 0.0051). Three piglets in the steel scalpel group developed urinomas. There were two perirenal abscesses, one in each group. In the steel scalpel group there was one intussusception. In conclusion, it seems that the combination Nd:YAG laser method offers no definitive advantage over the standard technique for partial nephrectomies in the pig.

The contact Nd:YAG laser: a new technique for conservation of the fallopian tube in unruptured ectopic pregnancy

Between August 1986 and April 1988, 22 women with unruptured tubal pregnancy were treated by laparoscopy in the Department of Gynaecology and Obstetrics at the University of Ulm. Linear salpingotomy was performed using the contact Nd:YAG laser technique. The laser beam was delivered by special sapphire probes attached to a standard optical fibre for incision and coagulation. Two different shapes of sapphire probes were used. The specific laser properties and the application of vasopressin enabled treatment without any other incision instruments or coagulation agents. In one patient subsequent laparoscopy became necessary due to persisting trophoblastic tissue. Sixteen women were assessed subsequently by second-look laparoscopy or hysterosalpingography for tubal patency and possible formation of adhesions. In 14 (88%) women the tubes were patent, and in two women adhesions were seen.

Combined thermal-photodisruptive iridotomy using the argon and neodymium:YAG laser

With the combined thermal-photodisruptive laser technique a large iridotomy of controllable size can be performed without any major complications. Using the Wise 103 diopter contact lens, primary coagulation is performed with short-duration argon laser burns. Subsequently, multiple low-energy single pulses are applied with the Nd:YAG. The iris can thus be perforated step by step. Compared with the pure Nd:YAG laser technique, this procedure reduces the risk of bleeding. Compared with the pure argon laser technique, each iris can be perforated easily, regardless of its color and thickness. The present paper reports on experience gathered in a first group of 50 eyes.