Effects of Er:YAG and Nd:YAG laser irradiation on radicular dentine permeability using different irrigating solutions

BACKGROUND AND OBJECTIVES: To evaluate the effect of Er:YAG and Nd:YAG laser on radicular dentine permeability when using distilled and deionized water and 1% NaClO as irrigating solutions. STUDY DESIGN/MATERIALS AND METHODS: Thirty human maxillary canines were divided randomly into six groups. The root canals were instrumented with K files and the step-back technique. Group I, irrigation with distilled and deionized water; Group II, irrigation with 1% NaClO; Group III, irrigation with distilled and deionized water and Er:YAG laser application (140 mJ input, 61 mJ output 15 Hz, 300 pulses, and 42 J); Group IV, irrigation with 1% NaClO and Er:YAG laser application (same parameters as Group III); Group V, irrigation with distilled and deionized water and Nd:YAG laser application (150 mJ, 15 Hz, 2,25 W); Group VI, irrigation with 1% NaClO and Nd:YAG laser application (same parameters as Group V). During laser application the teeth were always filled with the irrigating solution. The tip was withdrawn gently in helicoidal movement from the apex to the cervical portion. The teeth were processed for histochemical evaluation. RESULTS: The Tukey test showed that the cervical and middle thirds were statistically similar (P > 0.05) and significantly greater than the apical third (P < 0.05). The Scheffé test showed significantly greater dentine permeability in root canals in which water and Er:YAG laser were used and were significantly different from the other treatments (P < 0.05). CONCLUSIONS: The use of distilled and deionized water and Er:YAG laser showed the greater increase of dentine permeability. The use of 1% NaClO with Nd:YAG laser, distilled, and deionized water with Nd:YAG laser and the use of water increased dentine permeability less than the other groups. The use of 1% NaClO with and without Er:YAG laser application were positioned intermediately among the treatments.     

Ultrastructural changes of human dentin after irradiation by Nd:YAG laser

BACKGROUND AND OBJECTIVE: The use of Nd:YAG laser has been proposed for endodontic treatment. However, its ability to reduce dentin permeability, which is important for the success of root canal treatment, remains controversial. STUDY DESIGN/MATERIALS AND METHODS: Nd:YAG laser irradiation was performed in pulsed mode on human dentin. The parameters were: pulse energy (100 mJ), rate (10 pps), and total irradiation time (4 seconds). The crystalline phases, electron diffraction patterns, morphology, and microstructure of specimens after laser irradiation were observed by dark-field emission transmission electron microscope (TEM). RESULTS: Three ultrastructural zones could be delineated in the dentin: (1) an outer zone with an ordered columnar structure composed of hydroxyapatite and beta-tricalcium phosphate, (2) an intermediate zone composed of an amorphous substance (about 40-70 nm in diameter), and (3) an inner zone of well-crystallized hydroxyapatite grains. These three zones were free of pores or voids. CONCLUSIONS: Our study demonstrated that laser-irradiation might be used to reduce dentin permeability.     

Effects of Er:YAG laser and Nd:YAG laser treatment on the root canal dentin of human teeth: a SEM study

The objective of the study was to observe the morphological changes on root canal dentin after Er:YAG laser and Nd:YAG laser treatment. Twenty-one teeth biomechanically prepared were divided into three groups with seven teeth of each. Group A was unlased as a control. In group B, Er:YAG laser and in group C, Nd:YAG laser was applied to the root canal dentin. The roots were split longitudinally and examined using a scanning electron microscopy for the evaluation of debris, smear layer, and recrystallization. There was no statistically significant difference between the groups. This study indicates that laser beam is not effective in removing debris and smear layer.     

Interception of lymphatic drainage by Nd:YAG laser irradiation in rat urinary bladder

Lymphatic drainage can be demonstrated by colloidal indian ink injection. A small intramural indian ink spot in the bladder dome is separated from the rest of the rat urinary bladder by encircling transmural Neodymium-YAG (Nd:YAG) laser irradiation. In untreated animals there is an ink flow via the lymphatic vessels to the regional lymph nodes within several hours. In treated animals, after laser irradiation, the indian ink remains in the bladder dome and a penetration of the irradiated area cannot be found by macroscopic and histologic examination. Indian ink will be found in the regional lymph nodes after the ninth day of absorption of the coagulation necrosis and recanalisation of the intercepted lymphatics. Evidence for the interception of the lymphatic drainage is demonstrated by the distinctly delayed ink flow and the injected ink's remaining in the irradiated area. From this, we conclude that Nd:YAG laser irradiation is especially suitable for tumor coagulation, since simultaneous interception of lymphatic drainage will inhibit the spreading of tumor cells.     

Experimental study of partial liver resection with a combined CO2 and Nd:YAG laser

The use of the CO₂ laser in liver surgery is mainly limited by the lack of coagulation of the larger vessels. In an experimental study, partial liver resections were performed on pigs with a Nd:YAG as well as with a combined CO₂ and Nd: YAG laser. The best cutting efficiency was obtained with the CO₂ laser. On the other hand, the Nd:YAG laser and the combined laser sources showed excellent hemostasis at the cutting edge corresponding with a width of necrosis at about 5 mm in histomorphometric examination and zones with histologically different characteristics. Rebleedings from the resection lines were avoided in all cases using the combined CO₂ and Nd:YAG laser.     

Clinical application of the Nd:YAG laser endoscopy

We report here our clinical experiences with Nd:YAG laser therapy, and evaluate the results of this treatment. From July 1980 to December 1981, we carried out endoscopic laser treatment for 31 patients with 33 lesions. Bleeding gastric ulcers except stomal ulcers were treated successfully. For mucosal lesions of the stomach, Nd:YAG laser irradiation was effective in extirpating them. In advanced gastric cancers, symptoms of cardiac stenosis could be relieved in 80% of the cases. Endoscopic laser therapy was also effective in 80% of postoperative stenosis in the gastrointestinal tract. It is concluded that endoscopic irradiation with the Nd:YAG laser is useful for hemostasis and also for the treatment of malignant tumors and stenosis of the gastrointestinal tract.     

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目的 探讨弥漫性海绵状血管瘤治疗的新方法。方法 采用自行设计的治疗弥漫性海绵状血管瘤的新方法，即先以外科手术翻瓣显露血管瘤瘤体，应用Nd:YAG激光照射凝固血管瘤病灶，然后直接缝合创面，共收治22例四肢或躯干的弥漫性海绵状血管瘤。结果 22例病人术后无肢体功能障碍或切口大出血等并发症，经随访1－38个月，显效18例，占81.8％；有效4例，占18.2%；总有效率100％，无血管瘤复发情况。结论 手术联合Nd:YAG激光治疗弥漫性海绵状血管瘤具有操作简便，组织损伤小，出血少，疗效确切，并发症少等优点，为海绵状血管瘤治疗提供了新途径。     

CO2激光结合Nd:YAG激光治疗色素痣的临床观察

目的：评价CO2激光结合Nd：YAG激光治疗色素痣的疗效。方法：先用CO2激光选择连续脉冲，小功率输出，烧灼皮损到周围正常皮肤水平，继之用Nd：YAG激光治疗，治疗面部色素痣128例、768个皮损。结果：Ⅰ、Ⅱ级(痊愈 显效)率为96．76％。治疗次数平均为1.32次。结论：采用CO2激光结合Nd：YAG激光治疗面部色素痣疗效肯定，治愈率高，疗程短。多数患者无明显瘢痕形成。     

Preliminary study of the Nd:YAG laser in canine partial nephrectomy

Partial nephrectomy is effective in the treatment of segmental renal disease but hemostasis remains a challenge. In this preliminary investigation the Nd:YAG laser was used alone or as an adjunct to the scalpel in partial nephrectomies to determine if hemostasis could be improved. A technique of 100-W laser transection with occlusion of the renal artery was effective for partial nephrectomy and achieved complete hemostasis. Conditions of patent renal artery flow or renal cooling were associated with a reduction in necrosis depth with 100-W laser partial nephrectomies. All techniques were compatible with survival over the 5-day study period.     

Nd:YAG laser irradiation of an eye model: experimental analysis

This work reviews a series of experiments performed on an eye model to study physical effect relevant for a safe and effective use of the Q-switched Nd:YAG laser in ophthalmic microsurgery. The breakdown probability per laser pulse has been found to depend exponentially on the reciprocal laser field. This indicates that, as in transparent solids, electron avalanche ionization is likely the main mechanism for optical breakdown in liquids. Shielding of the retina, by the laser-induced plasma, is not very effective, but an appreciable degree of shielding is present, in burst operation, even after membrane disruption. A backscattered beam, which presents the typical properties of stimulated Brillouin scattering, has been observed in the eye model, with a threshold of approximately 5 X 10(9) W/cm2. This beam, which presents an irregular spatial structure with peaks of irradiance well above the average value, may produce damage of the internal wall of the cornea.     

Histological evaluations following 1,064-nm Nd:YAG laser resurfacing

BACKGROUND AND OBJECTIVES: The long pulse 1,064-nm Nd:YAG laser is used clinically to decrease rhytid formation. The dermal level at which this change occurs has not been established. This study attempts to answer these questions using a porcine skin model. STUDY DESIGN/MATERIALS AND METHODS: Non-randomized prospective experimental trial involving the domestic piglet treated serially with the long pulse 1,064-nm Nd:YAG laser. RESULTS: Collagen formation occurred at the level of the reticular dermis. After one laser treatment, a significant level of collagen formation was induced in the reticular dermis compared to controls. The greatest gain was observed after four laser treatments. Energy levels of 20, 30, 40, and 50 J/cm2 were evaluated. Although not statistically significant, 30 J/cm2 had the greatest effect on collagen formation. However, at 50 J/cm2, marked ablative changes to the epidermis were observed. CONCLUSIONS: The long pulse 1,064-nm Nd:YAG laser induces collagen formation in the reticular dermis in porcine skin.     

Nd:YAG laser irradiation to intraluminal mass lesions of the superior vena cava under laser balloon angioscopy in an experimental canine model

A laser balloon angioscopic procedure was developed in a canine model for intraluminal mass lesions in the superior vena cava, using an endoscope bearing a very thin balloon through which Nd:YAG laser could penetrate. The balloon was made from artificially modified natural latex rubber and well expanded with saline infused through a biopsy channel. The endoscopic image of the object obtained through direct contact of the balloon expanded with saline was clear enough to observe the internal surface or branches in not only normal, but also pathological conditions of the canine SVC. The Nd:YAG laser was able to be successfully irradiated through the balloon using this procedure which, although still in its preliminary state, may be a useful clinical, diagnostic and therapeutic tool of the future.     

倍频Nd:YAG激光治疗毛细血管扩张133例

目的:观察Versapulse可调长脉宽倍频Nd:YAG532nm激光(VPW532)治疗毛细血管扩张的疗效及安全性。方法:使用VPW532激光治疗毛细血管扩张133例,观察其疗效和不良反应。结果:133例患者中,应用VPW532激光治疗1～3次后,治愈104例,显效20例,有效9例,总有效率达93.2%。仅有6例出现暂时性色素沉着,均无瘢痕形成。结论:VPW532激光治疗毛细血管扩张疗效显著,副作用轻微。     

The Nd:YAG laser in neurological surgery

The Nd:YAG laser has been applied in microneuro-surgery and has been found to be quite effective in removing had and hemorrhagic tumors such as meningiomas, tumors of the deep skull base, or tumors deep in the ventricle. Another indication for the use of the Nd:YAG laser is to open the thick sellar floor in transsphenoidal operations.     

手术联合Nd:YAG激光治疗弥漫性海绵状血管瘤(附87例报告)

目的:探讨弥漫性海绵状血管瘤治疗的新方法。方法:作者设计了一种治疗弥漫型海绵状血管瘤的新方法,即先以外科手术翻瓣显露血管瘤瘤体,应用Nd:YAG激光照射凝固血管瘤病灶,然后直接缝合创面。1998年1月～2003年10月,共收治87例四肢或躯干的弥漫性海绵状血管瘤病人。结果:所有病人术后无肢体功能障碍或切口大出血等并发症。随访1～63个月,经临床及影像学检查评估,达显效者71例(81.6%);有效者16例(18.4%);总有效率为100%。无血管瘤复发情况。结论:手术联合Nd:YAG激光治疗弥漫性海绵状血管瘤具有操作简便、组织损伤小、出血少、疗效确切和并发症少等优点,为本病的治疗提供了新途径。     

Treatment of benign, semimalignant, and malignant skin tumors with the Nd:YAG laser

Reported are first experiences with Nd:YAG laser treatment of benign, semimalignant, and malignant skin tumors in 90 patients. Treated lesions included condylomata acuminata, basal cell carcinomas, solar keratosis, squamous cell carcinomas, and secondary malignant skin tumors. First clinical and histological results are promising, but long-term follow-up is required to judge the definite efficacy of this therapeutical modality.     

Temperature rise in biological tissue during Nd:YAG laser irradiation

Few data are available about temperature distribution in tissue during Nd:YAG laser irradiation. To study the heat distribution that produces tissue coagulation, we used a thermographic camera aimed orthogonally to the laser beam axis to obtain thermal maps. Immediately after surgical resection, specimens of human stomach were irradiated near the resected edge, and the heat emitted sideways was detected by an infrared image system. A magnifying lens mounted on the camera enabled us to obtain 0.1 mm spatial resolution of the isothermic curves. The thermal analysis showed that the maximum depth where the increase in temperature reached 25 degrees C (corresponding to a coagulation temperature of about 60 degrees C) was never greater than 3 mm, irrespective of the power and exposure time used. Moreover, the bidimensional thermal maps showed that the temperature did not decrease in a purely exponential fashion along the beam axis, but reached a maximum at about 1 mm beneath the surface. This fact, which confirms the decrepitation theorem, could explain the explosion inside the tissues observed in surgical application of the Nd:YAG laser.