Computer-assisted evaluation of microleakage after apical resection with laser and conventional techniques

The purpose of this in vitro study was to observe the morphological changes and apical dye penetration at apical dentin surfaces after apicoectomy with conventional techniques and laser beam. Sixty single-rooted extracted teeth were selected for the study. The crowns were resected below the cemento-enamel junction. Then, these teeth were treated endodontically and filled with gutta-percha using AH-26 root canal sealer. The teeth were randomly divided into four groups of 15 teeth in each. The roots were resected perpendicular to its long axis 3 mm from the apex using Er: yttrium–aluminium–garnet (YAG) laser irradiation in groups 1 and 2, and the resected root surfaces were lased with Nd:YAG laser in group 2. The apexes were resected by a high-speed handpiece in groups 3 and 4, and the resected root surfaces were lased with Nd:YAG laser in group 4. Ten teeth in each group were used for leakage studies, and the other five teeth were used for scanning electron microscopic examinations. Seven sections were obtained from each root to assess the microleakage, and the sections were analyzed in a computer-assisted manner. No statistically significant differences were observed between the leakage percentage of groups 1 and 3 and groups 2 and 4 (p > 0.05). Morphological differences were observed between apical dentin surfaces resected with conventional techniques and laser beam.     

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.     

Computer analysis of laser dosimetry data: a method of accurate energy density delivery

In the past, utilization of the laser in medicine has been limited by the lack of accurate quantification of the energies delivered to the tissue. Data obtained in the course of this investigation have demonstrated the relationships which exist between the energy delivered to the tissue and the optical system composed of the fiber and focusing lens. A continuous-wave multimode Nd:YAG laser (1,064 nm) was used in these experiments. Utilizing the beam scan technique previously described, we recorded over 100 beam profiles at various distances from the handpiece (fiber optic and lens). Computer analysis of our data established the mathematical correlation between the surface area of the irradiated spot and the distance of the handpiece to the target, thus allowing us to predict the surface area of the irradiated spot to any desired distance. By duplicating our methods with his particular optical system, the clinician or any laser user has the capacity to determine the energy delivered to the tissue (J/cm2) by knowing the power of the laser (watts), the time of exposure (seconds), and the distance of the handpiece to the treatment site (centimeters).     

Effect of tissue pressure on contact laser insults.

The effect of variations in tissue pressure transmitted through contact laser probes during tissue ablation has been investigated. Weights of 10 and 50 g were transmitted through the tip of the probes onto the gastric and colorectal wall. At all laser energies the depth of tissue vaporization was significantly greater at the higher tissue pressure with perforation of the viscus occurring at laser energies above 10 J. The lateral zones of thermal tissue necrosis were not influenced by tissue pressure. Deformation of the wall of the viscus under the pressure of the probe was identified as a sign of excessive tissue pressure likely to result in perforation of any tissue of similar thickness to the normal gastric or colorectal wall.     

Histologic evaluation of the pulsed Nd:YAG laser for laser lipolysis

BACKGROUND AND OBJECTIVES: Laser lipoplasty with pulsed Nd:YAG laser, widely used in Europe and Latin America, has recently been introduced in Japan and the USA. We report histologic analyses of the effects of the laser on human fat tissue. STUDY DESIGN/MATERIALS AND METHODS: Freshly excised human skin and subcutaneous fat were irradiated with the pulsed Nd:YAG laser (SmartLipo, DEKA, Italy). A 1,064 nm laser at 40 Hz and 150 mJ and 100 microseconds-long pulses were used. Methods of exposure were the same as in the clinical application. In the control group, the specimens were cannulated by the handpiece without irradiation. The tissue was studied by scanning electron microscopy and hematoxylin eosin staining. RESULTS: Scanning electron microscopy after irradiation showed greater destruction of human adipocytes than in the control. Degenerated cell membrane, vaporization, liquefaction, carbonization, and heat-coagulated collagen fibers were observed. CONCLUSIONS: Our study showed that the SmartLipo appeared to be histologically effective for destruction of human fat tissue.     

Effects of different contact laser scalpels on skin and subcutaneous fat

The tissue effects of different Nd:YAG contact laser scalpels on pig skin and subcutaneous fat were studied using various power settings. Three different laser scalpels were tested: 0.2 mm nonfrosted (LR2), 0.6 mm nonfrosted (LR6), and 1.0 mm frosted (LRP10), using 3 different power settings (8 W, 14 W, 18 W). The tissue effects of a steel scalpel were used as reference. Incisions on pig loin (40/pig) were made at randomized sites. Specimens were taken at postoperative days 0 and 14. The depth of tissue damage was measured using a light microscope. The amount of time required for making each incision was recorded. Significant differences between the LR2 and the LR6 were observed in the skin at 2 weeks (P less than .05) at all power settings used, indicating superiority of the smaller scalpel for use in skin incisions. The LRP10 did not cause more tissue damage than did the LR6 in any of the power settings used. In subcutaneous fat the smallest scalpel (LR2) caused significantly less tissue damage evident at 2 weeks postoperatively (P less than .05) than did the other two laser scalpels, whereas the effects of the different power settings were minor. The incision time in skin decreased by more than 50% when the power was increased from 8 W to 18 W for all laser scalpels studied.     

Clinical application of Nd:YAG laser for the treatment of small hepatocellular carcinoma with new shaped laser probe

BACKGROUND AND OBJECTIVES: Surgical resection of hepatocellular carcinoma (HCC) is not always regarded as the first choice of treatment, because most HCCs develop in cirrhotic liver. It becomes adaptation of minimally invasive treatments for HCC. In animal experiments, we previously reported that our newly developed neodymium:yttrium aluminum garnet (Nd:YAG) laser system could ablate liver tissue in short periods. STUDY DESIGN/PATIENTS AND METHODS: Six HCC cases (mean diameter; 16.3 +/- 3.50 mm) were enrolled. The Nd:YAG laser generator with a wavelength of 1,064 nm at 10 W of power emitted the laser in a forward fashion and in all patients the laser beam safely irradiated the target lesion. RESULTS: There was no recurrence of HCC in the laser-ablated area in six patients for duration of 21.8+/- 4.35 months. A local recurrence was found in only one patient. CONCLUSIONS: This study showed the clinical usefulness of laser ablation in the treatment of HCC.     

大功率钬激光治疗膀胱结石初步临床研究

目的 研究大功率（６０Ｗ以上）钬激光粉碎结石的性能及其有效合理的碎石参数。方法：（１）体外实验，将１２枚泌尿系结石（结石成分为尿酸结石，草酸结石，磷酸结石，大小１．０～２．０ｃｍ）浸于生理盐水中，在不同钬激光参数设置下，用钬激光粉碎结石（结石粉碎至〈０．５ｍｍ）观察钬激光碎石能力，合理有效的参数设置及对不同成分结石的碎石情况等。（２）临床应用，经耻骨上穿刺，用大功率钬激光治疗膀胱结石６例，结石成分     

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.     

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.     

Histologic evaluation of rat mammary tumor necrosis by interstitial Nd:YAG laser hyperthermia.

The extent of coagulative necrosis caused by interstitial laser hyperthermia was measured for different quantities of laser energy in a rat mammary tumor model. Continuous wave Nd:YAG laser at a power level of 5 W was focused onto a 600 mu diameter bare tip quartz fiber and placed inside a 19-gauge needle, which allowed the para-axial flow of normal saline at 1 cc/min. A microthermocouple soldered to the outside of the probe continuously provided the interstitial temperature. After the probe was inserted into the tumor, it was withdrawn as laser energy was administered at a rate sufficient to maintain the temperature within 42-45 degrees C. Tumors were excised after 48 hours, fixed in formalin, cut in 3 mm slices, and the coagulated surfaces measured microscopically. Laser fiber transmission loss was 1% per 1,000 J of laser energy and the average time required to coagulate 1 cc of tumor was 2 minutes. There was a statistically significant correlation between the volume of tumor necrosis and the level of laser irradiation (r = 0.71, P less than 0.001). It is concluded that the described technique is an efficient method of tumor coagulation by interstitial laser hyperthermia and proportionally larger volumes of necrosis are created with greater amounts of laser energy.     

Effective outpatient treatment of Kaposi's sarcoma of the urethral meatus using the neodymium:YAG laser

An unusual presentation of acquired immunodeficiency syndrome (AIDS)--a case of Kaposi's sarcoma involving the glans penis and fossa navicularis--was treated palliatively with neodymium:YAG (Nd:YAG) laser photoablation. A single outpatient treatment removed the two lesions and restored the patient's ability to void normally. The Nd:YAG laser proved extremely useful, providing effective outpatient therapy with minimal morbidity and excellent local results.     

Endoscopic laser therapy of the watermelon stomach.

Endoscopic laser therapy has been used in the treatment of vascular lesions throughout the gastrointestinal tract. The "watermelon stomach" is a pattern of vascular ectasia in the gastric antrum that results in chronic gastrointestinal blood loss and iron deficiency anemia. We have treated 7 transfusion dependent patients with a watermelon stomach using endoscopic laser therapy. Four of these patients were treated with the argon laser and 3 with the Nd:YAG laser. Patient age and prior transfusion requirements were similar in both groups. The mean number of treatments to obliterate vascular lesions and eliminate the need for transfusions was 5.75 +/- 0.89 (SEM) for the argon laser and 2.33 +/- 0.27 for the Nd:YAG laser (P < 0.05). Lesions recurred and required retreatment in 1 patient treated with the Nd:YAG laser and 3 patients treated with the argon laser (mean follow-up of 35 months). We conclude that endoscopic laser therapy with either the argon or Nd:YAG laser is an effective treatment modality for antral vascular ectasia (watermelon stomach). The Nd:YAG laser requires fewer treatment sessions than the argon laser to obliterate the lesions without increased risk of complications.     

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.     

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。     

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.     

1064nm长脉冲激光联合曲安奈德治疗瘢痕疙瘩

目的 探讨1064 nm长脉冲激光联合曲安奈德局部注射治疗瘢痕疙瘩的临床疗效.方法 将78例患者随机分为两组:治疗组41例,采用1064 nm长脉冲钕∶钇-铝-石榴石(Nd∶ YAG)激光联合曲安奈德注射液局部注射;对照组37例,仅局部注射曲安奈德.复诊每隔3周1次,未痊愈及复发者继续治疗,4次为1个疗程,共观察2个疗程.分别于第1、第2个疗程结束后判断疗效和不良反应,随访1年以验证复发情况.结果 第1个疗程后治疗组痊愈率21.95％,有效率73.17％;对照组痊愈率10.81％,有效率45.95％,治疗组有效率明显高于对照组(P＜0.05);第2个疗程后治疗组痊愈率70.73％,有效率100％,对照组痊愈率45.95％,有效率83.78％,治疗组痊愈率及有效率均明显高于对照组(P＜0.05).结论 长脉冲1064 nm激光联合曲安奈德局部注射治疗瘢痕疙瘩见效快,副作用小、治愈率高,疗效确切.     

Nd:YAG laser excision of a giant gingival pyogenic granuloma of pregnancy

A 19-year-old Hispanic nullipara experienced the rapid growth of an oral lesion on the right lower gingiva which she had first noticed at 29 weeks gestation. The lesion interfered with oral hygiene and eating. At surgery, the lesion measured 3.5 × 2.5 × 2.0 cm. Biopsy confirmed a pyogenic granuloma (“granuloma gravidarum”). Panorex films showed no bony invasion. The lesion was excised using the Nd:YAG laser under general anesthesia when the patient had reached 36 3/7 weeks gestation. We chose the Nd:YAG laser over the CO₂ laser for the removal of this very vascular lesion, because of its superior coagulation characteristics. This technique results in removal of the lesion with less danger of bleeding than with any other surgical technique. The patient did well postoperatively, delivered a healthy 3,884 g infant at 40 6/7 weeks gestation, and has had no recurrence after 15 months of follow-up. © 1994 Wiley-Liss, Inc.     

Hemostasis and healing of superficial splenic injuries using Nd:YAG laser and nonsuture techniques: Preliminary report

This study was designed to compare Nd:YAG laser to fibrin glue, electrocautery, and avitene in the management of superficial splenic injury. Six dogs were submitted to laparotomy. A #11 blade scalpel was used to sharply excise the splenic capsule inflicting four 1″ × 1″ superficial injuries on each spleen. The lesions were treated. All animals had a second laparotomy (“first relaparotomy”); 2 dogs each were reexplored on postop days 3, 7, and 14. Morphologic and histologic observations were made. A third and final relaparotomy was performed on all dogs at 21 days with repeated morphologic and histologic assessments. Hemostatic times, grades of adhesions, and microscopic changes were not significantly different among the various treatments (P > 0.25). Capsular plaque formations were significantly different at the first relaparotomy (P < 0.01) and at final relaparotomy (P < 0.05). Both adhesions and capsular plaque formation were least at fibrin glue-treated sites, whereas Nd:YAG (1.06 μm) was most effective for average hemostatic time (mean = 109.67 s). Electrocautery produced the greatest necrosis at treatment sites. We conclude that all modalities are effective in controlling hemorrhage. © 1994 Wiley-Liss, Inc.