A prospective randomized controlled trial of hybrid laser treatment or transurethral resection of the prostate, with a 1-year follow-up

OBJECTIVE: To compare the clinical outcome after hybrid laser treatment of the prostate, combining potassium titanyl phosphate (KTP) and Nd:YAG lasers, with transurethral resection of the prostate (TURP). PATIENTS AND METHODS: A prospective randomized trial was conducted to compare laser treatment and TURP. The hybrid laser treatment technique involved performing initial 30 W KTP vaporizing bladder neck incisions and prostatotomies followed by a 'free-paint' application of 60 W Nd:YAG coagulation energy. Patients were re-assessed after 6 weeks, 6 months and 1 year, using the International Prostate Symptom Score (IPSS) and uroflowmetry. TURP was conducted using conventional methods. RESULTS: In all, 204 patients were randomized into the study; at 6 weeks there were significant differences between the groups for the IPSS (12.4 vs 9.1, P=0.001) and maximum urinary flow rates (16.1 vs 20.8 mL/S, P<0. 001) in favour of the TURP group. At 6 months and one year this difference had disappeared. Similar numbers of patients in each group complained of bothersome postoperative urinary symptoms (23% vs 19%). Blood transfusions (5% vs none) and urethral strictures (9% vs 2%) were more common after TURP, whereas more early infective complications occurred after hybrid laser treatment (24% vs 5%). Only one patient in each group required re-operation because of poor resolution of symptoms. CONCLUSIONS: At one year, hybrid KTP/Nd:YAG laser treatment of the prostate was equivalent to TURP in the improvements in IPSS, maximum urinary flow rate and post-void residual urine.     

Quality of life changes following KTP/Nd:YAG laser treatment of the prostate and TURP.

OBJECTIVE: To compare health-related quality of life (HRQL) changes in patients receiving hybrid KTP/Nd:YAG laser treatment of the prostate with TURP. PATIENTS AND METHODS: Patients complaining of symptomatic benign prostatic enlargement were studied. Their symptoms (IPSS), disease-specific (BPH Impact Index (BPHII)) and generic HRQL (Short Form-36 (SF-36)) was evaluated before and at 6 weeks, 6 months and 1 year following treatment. RESULTS: 204 patients were randomized into the study. Patients in both groups reported an improvement in IPSS and BPHII at each postoperative assessment, but there were significant differences between the two groups at the 6-week stage in favor of the TURP group. At 6 weeks, patients in the laser group reported significantly worse scores in the SF-36 domains of bodily pain, social function and role emotional when compared to the TURP group. These differences disappeared at both the 6-month and 1-year follow-up assessments. CONCLUSIONS: Although hybrid KTP/Nd:YAG laser treatment and TURP differed in the way they affected patients in the early postoperative period, at 1 year, patients reported similar improvements in symptoms and enjoyed a similar disease-specific and generic HRQL.     

Qualitative microanalysis of ions and ultrastructural changes in dentin exposed to laser irradiation and to metal salts solution

BACKGROUND AND OBJECTIVES: This study evaluated the ultrastructural changes in dentin after treatment with the Nd:YAG laser and/or metal salt solutions and verified the presence of Sn++, Sr++, and F- in dentin structure. STUDY DESIGNS/MATERIALS AND METHODS: Sixty dentin disks were randomly divided into groups (n = 10): (I) control (no treatment), (II) Nd:YAG (1.5 W, 100 mJ, 15 Hz, 125 J/cm2), (III) 10% SnF2 aqueous solution for 30 minutes, (IV) Nd:YAG+10% SnF2 aqueous solution for 30 minutes, (V) 10% SrCl2 toothpaste for 30 minutes, (VI) Nd:YAG+10% SrCl2 toothpaste for 30 minutes. Then, all samples were prepared for scanning electron microscopy (SEM) and the samples from Groups I to IV for the energy dispersive X-ray microanalysis (EDX). RESULTS: SEM evaluation revealed occluded dentinal tubules and a dentin surface altered by the laser irradiation. The EDX microanalysis revealed Sn++ at a depth of 250 microm in Group IV and not deeper than 100 microm in Group III. In Group V, Sr++ was not deeper than 50 microm, but it could be detected at a depth of 500 microm in Group VI. F- was found only in Group IV. CONCLUSIONS: Ultrastructural changes caused by laser irradiation can increase dentin uptake of Sn++, Sr++, and F-.     

Clinical evaluation of enhanced nonablative skin rejuvenation using a combination of a 532 and a 1,064 nm laser

BACKGROUND AND OBJECTIVES: Improvements in the physical signs of photoaging can be achieved by non-invasive laser resurfacing procedures. To evaluate the effectiveness and safety of the Nd:YAG 1,064 nm and KTP 532 nm lasers for non-invasive skin rejuvenation. STUDY DESIGN/PATIENTS AND METHODS: Subjects requesting non-invasive skin rejuvenation underwent two treatments with the 532 nm laser to one side of the face and with both lasers to the other side, followed by three treatments with the 1,064 nm laser to both sides. Skin characteristics were evaluated before, during, and up to 4 months after treatment. RESULTS: A >25% improvement in overall skin condition was observed for >30% of subjects at the 1 month follow-up and >40% of subjects at the 4 month follow-up. The greatest improvements were observed for visual dryness, roughness, and uneven pigmentation. No adverse events were reported. There was a trend for greater improvement in patients who received more 1,064 nm treatments but this was not statistically significant. CONCLUSIONS: The 532 nm KTP and 1,064 nm Nd: YAG lasers can be effectively and safely used for non-invasive skin rejuvenation.     

Limited lung resection using the potassium-titanyl-phosphate laser

BACKGROUND AND OBJECTIVES: Recently, the use of the potassium-titanyl-phosphate (KTP) laser with a wavelength of 532 nm, which is half the wavelength of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, has been expanding in many fields, since this laser offers hemostasis and vaporization with minimal coagulation of the underlying structures. The purpose of this study was to determine the usefulness of the KTP laser in limited lung resection done for pulmonary nodular lesions. STUDY DESIGN/PATIENTS AND METHODS: We used the KTP laser to manage 10 partial resections (Group 1) and 16 segmentectomies (Group 2). The variables that were used to compare the two methods of resection included intra-operative blood loss, mean drainage time, and post-operative morbidity. RESULTS: The mean intra-operative blood loss was smaller in Group 1 (152.8 +/- 65.0 cc, P = 0.002) than in Group 2 (341.9 +/- 178.6 cc). Mean drainage time was shorter in Group 1 (1.8 +/- 1.0 days, P = 0.0141) than in Group 2 (3.6 +/- 2.9 days). The results of both groups with respect to hemostatic and healing effects were satisfactory. On histopathologic evaluation, the KTP laser-irradiated field tissue alteration consisted of two layers with a depth up to 2 mm. CONCLUSIONS: The results of this study suggest that the KTP laser has the potential to become a useful and reliable tool for limited lung resection.     

Transurethral Visual Laser Ablation of the Prostate for Benign Prostatic Hyperplasia Using a KTP/YAG Laser

Background :
Transurethral visual laser ablation of the prostate (VLAP) has been established as an alternative method for the treatment of benign prostatic hyperplasia (BPH). However, most VLAP procedures utilize only a neodymium:yttrium-aluminum-gamet (Nd:YAC) laser. Since a potassiumtitenyl-phosphate (KTP) laser offers limited tissue penetration, KTP can be safely utilized to excise part of the obstructing prostatic tissue. This study assessed the interaction between KTP vaporization and YAG coagulative ablation to determine the safety and efficacy of VLAP utilizing a combined KTP/YAG treatment.
Methods :
Forty patients with bladder outlet obstruction secondary to BPH were treated with VLAP using a KTP/YAG laser. The laser light was delivered by an angle delivery device.
Results :
Most cases demonstrated a significant improvement in routine subjective and objective parameters (AUA symptom score, peak flow rate, average flow rate, and amount of residual urine). No significant complications relating to this procedure were reported, however, 4 patients experienced postoperative acute urinary retention.
Conclusion :
KTP/YAG laser ablation of the prostate is safe and effective for the treatment of BPH.     

Photoselective vaporization of the prostate: initial experience with a new 80 W KTP laser for the treatment of benign prostatic hyperplasia

PURPOSE: To study the safety and efficacy of a new high-power potassium-titanyl-phosphate laser (KTP/532; Niagara PV trade mark laser system; Laserscope, San Jose, CA) for transurethral photoselective vaporization of benign obstructive prostate tissue. PATIENTS AND METHODS: The KTP/532 laser energy at 80 W was delivered by a 6F side-firing fiber through a 23F continuous-flow cystoscope. Photoselective vaporization of the prostate (PVP) using sterile water irrigation was performed under spinal anesthesia on an outpatient basis in 10 patients with a preoperative mean prostate volume of 41.37 +/- 18.5 cc (range 24-76.3 cc). The mean lasing time was 19.8 +/- 4.9 minutes. RESULTS: Two patients experienced 1 to 7 days of mild dysuria, and one who was taking warfarin had mild transient hematuria, but none had urinary retention or other complications. The mean catheterization time was 17.2 +/- 9.6 hours (range 0-28 hours). At 1 year, the outcomes, which had showed significant improvement sustained throughout the follow-up, were as follows: mean American Urological Association Symptom Score decreased from 23.2 +/- 4.7 to 2.6 +/- 0.5 (88.8%), the mean quality of life score improved from 4.3 +/- 0.7 to 0.4 +/- 0.5 (90.7%), the mean peak urinary flow rate increased from 10.3 +/- 1.4 mL/sec to 30.7 +/- 5.8 mL/sec (198.1%), and the mean postvoiding residual volume decreased from 137.6 +/- 112.2 mL to 3.0 +/- 4.8 mL (97.8%). The mean prostate volume decreased by 27%. CONCLUSIONS: This pilot study indicates that PVP with the new 80 W KTP/532 laser is a simple, safe, and efficacious outpatient procedure for the treatment of obstructive BPH.     

Depth of penetration of the neodymium: yttrium-aluminum-garnet laser in the human prostate and clinical results of high-dose laser energy in 50 patients

Summary We evaluated the treatment of the human prostate with the Nd:YAG laser using a Cytocare Prolase II fiber. We utilized this first in 12 patients prior to radical prostatectomy and then appropriately serially sectioned the prostate to measure the depth of penetration. The studies clearly revealed that 60 W of power and 60 s of pulse duration gave the most consistent depth of penetration in the human prostate model. This depth of penetration averaged 2 cm in the glands that were removed. At the same time there was absolutely no evidence of damage to the neurovascular bundle or to the capsule of the prostate using the above-mentioned dosimetry regime. This study was then transferred to our initial experience in treating 50 patients with benign prostatic hypertrophy and obstructive voiding symptoms. The first 25 patients were also treated with so-called spot radiation of the prostate, whereas the second 25 patients were treated by total photoirradiation of all visible endoscopic tissue. The results reveal that both groups of patients had a fairly highly satisfactory result as measured objectively with American Urological Association (AUA) symptom scores and uroflow studies. In the latter group (photoirradiation of all visible endoscopic tissue) a significantly higher dose of laser energy was utilized and a smaller failure rate was noted on a long-term basis in patients who subsequently came to transurethral resection of the prostate (TURP) because of failure of the laser procedure. At the same time that the patients were treated, all 50 patients underwent multiple random needle biopsies of the peripheral zone of the prostate, and at no time was there any evidence of a laser effect in the capsule of the human prostate from a dosimetry of 60 W and 60 s of pulse duration and total photoirradiation of the entire prostate. Very large doses of energy were used, ranging up to 110,000 J per case. It is our impression that the 60-W/60-s protocol will consistently yield the best results in terms of success of laser prostatectomy as measured objectively with uroflow and AUA symptom score as well as providing total safety in term of the absence of damage to the capsule of the prostate despite photoirradiation of all visible viable tissue at high total doses of energy.     

Photoselective KTP laser vaporization of the prostate: first experiences with 65 procedures

PURPOSE: To study the feasibility and efficacy of 80 W potassium-titanyl-phosphate (KTP) laser vaporization (GreenLight PV; Laserscope) of the prostate in patients suffering from voiding dysfunction secondary to benign prostatic hyperplasia (BPH) or known locally advanced prostate cancer (CaP). PATIENTS AND METHODS: Sixty-five patients with symptomatic BPH (N=57) or obstructive voiding secondary to CaP (N=8) with a mean age of 70 +/- 10 years (range 46-93 years) underwent photoselective 80 W KTP laser vaporization of the prostate. All consecutive patients, including 34 with a history of chronic urinary retention or indwelling catheter, were enrolled. Prostate specific antigen (PSA) values, prostate volume as measured by transrectal ultrasonography, urinary peak flow measurement (Qmax), postvoiding residual volume (PVR) measured transvesically, and International Prostate Symptom Score (IPSS) were assessed preoperatively, on the day of discharge, and 1 month and 3 months postoperatively. The mean preoperative prostate volume was 49 +/- 32 cc (range 15-250 cc). RESULTS: In all 65 patients, KTP laser vaporization was performed successfully, with a mean operating time of 57 +/- 25 minutes (range 10-160 minutes). No major complication occurred intraoperatively or postoperatively, and no transfusions were necessary. All patients were catheter free after 1 month. At 1 month and 3 months, the urinary peak flow had increased from 7.7 +/- 2.8 mL/sec preoperatively to 20.9 +/- 11.6 mL/sec (+171%) and 18.2 +/- 6.3 mL/sec (+136%), respectively. The IPSS decreased from 18.5 +/- 6.7 to 9.2 +/- 7.7 (-50%) and 7.2 +/- 5.9 (-61%) at 1 and 3 months, respectively. CONCLUSIONS: A 80 W KTP laser vaporization of the prostate technique instantly removes obstructive tissue. A transurethral resection-like visible cavity is the endpoint. Immediate symptom relief is achieved in a truly minimally invasive way with a very low postoperative complication rate within 3 months' follow-up.     

Color vision deficits and laser eyewear protection for soft tissue laser applications

PURPOSE: Laser safety considerations require urologists to wear laser eye protection. Laser eye protection devices block transmittance of specific light wavelengths and may distort color perception. We tested whether urologists risk color confusion when wearing laser eye protection devices for laser soft tissue applications. MATERIALS AND METHODS: Subjects were tested with the Farnsworth-Munsell 100-Hue Test without (controls) and with laser eye protection devices for carbon dioxide, potassium titanyl phosphate (KTP), neodymium (Nd):YAG and holmium:YAG lasers. Color deficits were characterized by error scores, polar graphs, confusion angles, confusion index, scatter index and color axes. Laser eye protection device spectral transmittance was tested with spectrophotometry. RESULTS: Mean total error scores plus or minus standard deviation were 13+/-5 for controls, and 44+/-31 for carbon dioxide, 273+/-26 for KTP, 22+/-6 for Nd:YAG and 14+/-8 for holmium:YAG devices (p <0.001). The KTP laser eye protection polar graphs, and confusion and scatter indexes revealed moderate blue-yellow and red-green color confusion. Color axes indicated no significant deficits for controls, or carbon dioxide, Nd:YAG or holmium:YAG laser eye protection in any subject compared to blue-yellow color vision deficits in 8 of 8 tested with KTP laser eye protection (p <0.001). Spectrophotometry demonstrated that light was blocked with laser eye protection devices for carbon dioxide less than 380, holmium:YAG greater than 850, Nd:YAG less than 350 and greater than 950, and KTP less than 550 and greater than 750 nm. CONCLUSIONS: The laser eye protection device for KTP causes significant blue-yellow and red-green color confusion. Laser eye protection devices for carbon dioxide, holmium:YAG and Nd:YAG cause no significant color confusion compared to controls. The differences are explained by laser eye protection spectrophotometry characteristics and visual physiology.     

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.     

Free-beam and contact laser ablation of benign prostatic hyperplasia with the KTP/Nd:YAG laser: efficacy and versatility

Summary This report details the use of the free-beam Nd: YAG laser alone and in combination with contact vaporization for treatment of benign prostatic hyperplasia. Improvements in urinary flow rates and symptoms were noted along with a high degree of patient satisfaction. The portable KTP/Nd:YAG laser wavelengths and the variety of optical fiber configurations provide versatility to the surgeon. This study further supports the use of laser energy as a means to treat urinary outflow obstruction from prostatic enlargement in selected cases.     

Two-year follow-up results of a prospective randomized trial comparing hybrid laser prostatectomy with TURP in the treatment of big benign prostates

OBJECTIVE: We compared conventional transurethral electroresection of the prostate (TURP) and hybrid laser treatment in patients with symptomatic bladder outflow obstruction caused by a benign prostate bigger than 40 ml. MATERIAL AND METHODS: Forty-six patients with symptomatic urodynamically confirmed outflow obstruction caused by benign prostate hyperplasia bigger than 40 ml were accepted to the prospective trial and were randomized to receive hybrid laser treatment or TURP. The hybrid laser technique involved initial non-contact Nd:YAG coagulation followed by contact Nd:YAG vaporization to open the prostatic urethra. Patients were re-assessed after 3, 6, 12 and 24 months. RESULTS: Of the 46 patients, 37 (80%) were available at the 24-month follow-up. The re-operation rate was 14.3% in the hybrid laser group and 8.3% in the TURP group. The decrease in DanPSS-1 symptom score from baseline at 24 months was 51.0% in the hybrid laser group (p<0.01) and 80.0% in the TURP group (p<0.001), with no statistically significant differences between the groups. Early improvement in objective urinary parameters of peak urinary flow rate and residual urinary volume showed deterioration in hybrid laser group during longer follow-up, whereas in TURP group the improvement of these variables was sustained. Comparison between groups showed TURP to be superior in peak urinary flow rate (p < 0.001) and residual urinary volume (p < 0.01) at the 24-month follow-up visit. CONCLUSIONS: Both hybrid laser treatment and TURP give good symptomatic relief lasting at least 2 years in the treatment of big obstructing prostates, but hybrid laser treatment is associated with a higher re-operation rate because of inadequate initial prostate tissue removal and with inferior outcome in objective urinary parameters compared with TURP.     

Transcutaneous laser treatment of leg veins

Leg telangiectasias and reticular veins are a common complaint affecting more than 80 % of the population to some extent. To date, the gold standard remains sclerotherapy for most patients. However, there may be some specific situations, where sclerotherapy is contraindicated such as needle phobia, allergy to certain sclerosing agents, and the presence of vessels smaller than the diameter of a 30-gauge needle (including telangiectatic matting). In these cases, transcutaneous laser therapy is a valuable alternative. Currently, different laser modalities have been proposed for the management of leg veins. The aim of this article is to present an overview of the basic principles of transcutaneous laser therapy of leg veins and to review the existing literature on this subject, including the most recent developments. The 532-nm potassium titanyl phosphate (KTP) laser, the 585–600-nm pulsed dye laser, the 755-nm alexandrite laser, various 800–983-nm diode lasers, and the 1,064-nm neodymium yttrium–aluminum–garnet (Nd:YAG) laser and various intense pulsed light sources have been investigated for this indication. The KTP and pulsed dye laser are an effective treatment option for small vessels (<1 mm). The side effect profile is usually favorable to that of longer wavelength modalities. For larger veins, the use of a longer wavelength is required. According to the scarce evidence available, the Nd:YAG laser produces better clinical results than the alexandrite and diode laser. Penetration depth is high, whereas absorption by melanin is low, making the Nd:YAG laser suitable for the treatment of larger and deeply located veins and for the treatment of patients with dark skin types. Clinical outcome of Nd:YAG laser therapy approximates that of sclerotherapy, although the latter is associated with less pain. New developments include (1) the use of a nonuniform pulse sequence or a dual-wavelength modality, inducing methemoglobin formation and enhancing the optical absorption properties of the target structure, (2) pulse stacking and multiple pass laser treatment, (3) combination of laser therapy with sclerotherapy or radiofrequency, and (4) indocyanin green enhanced laser therapy. Future studies will have to confirm the role of these developments in the treatment of leg veins. The literature still lacks double-blind controlled clinical trials comparing the different laser modalities with each other and with sclerotherapy. Such trials should be the focus of future research.     

Comparative evaluation of the effects of Nd:YAG and Er:YAG laser in dentin hypersensitivity treatment

Dentin hypersensitivity (DH) is one of the most common complications that affect patients after periodontal therapy. So far, many investigators have successfully used different types of laser on DH treatment. The aim of this study was to evaluate the comparative effect of Nd:YAG laser and Er:YAG laser on human teeth desensitization. A group of nine patients with a total of 63 chronic hypersensitive teeth were selected. Each one of them should at least have three hypersensitive teeth. These teeth were randomly allocated into three groups. Group 1, Nd:YAG laser (1 W, 15 Hz, 60 s, two times); group 2, Er:YAG laser (100 mJ, 3 Hz, 60 s, two times); and group 3 serves as control group without any treatment. Assessment of pain was performed by a visual analysing scale (VAS) after stimulation of sensitive tooth by using the sharp tip of an explorer. This test was performed before treatment, immediately after that and at 1-, 3- and 6-month intervals after treatment by one blinded examiner. Analysis of VAS score between the three groups at the time of treatment did not show any significant difference (p = 0.506). However, by using repeated-measurement analysis of variance test, significant differences were seen in the three groups between before-treatment VAS score and after treatment (p < 0.0005). This statistically significant difference in the control group demonstrated a placebo effect. However, the effect of using Nd:YAG and Er:YAG lasers was stronger than this placebo effect, so that after removing the effect of the placebo, differences immediately after, 1, 3 and 6 months post treatment between all three groups still were statistically highly significant (p < 0.0005). Compared to the Er:YAG laser group, using Nd:YAG laser resulted in a significant reduction of VAS score at each follow-up examination (p < 0.0005). Although using Nd:YAG and Er:YAG laser in desensitization of hypersensitive teeth showed a placebo effect limited to a short time, results of this study demonstrated that both of these lasers have an acceptable therapeutic effect. The observed effects seemed to last for at least 6 months. It was concluded that Nd:YAG laser is more effective than Er:YAG laser in reduction of patients’ pain.     

Morphologic changes and removal of debris on apical dentin surfaces after Nd:YAG laser and diode laser irradiation

OBJECTIVE: To verify the effects of laser energy on intracanal dentin surfaces, by analyzing the morphologic changes and removal of debris in the apical third of 30 extracted human teeth, prepared and irradiated with the Nd:YAG laser and diode laser. BACKGROUND DATA: Lasers have been widely used in endodontics. The morphologic changes in dentin walls caused by Nd:YAG and diode laser irradiation could improve apical seals and cleanliness. MATERIALS AND METHODS: The protocol used for Nd:YAG laser irradiation was 1.5 W, 100 mJ, and 15 Hz, in pulsed mode, and for diode laser was 2.5 W in continuous mode. Each specimen was irradiated four times at a speed of 2 mm/sec with a 20-sec interval between applications. Five calibrated examiners scored the morphologic changes and debris removal on a 4-point scale. RESULTS: In analyzing the scores, there were no statistically significant differences between the two types of laser for either parameter, according to Kruskal-Wallis testing at p = 0.05. The SEM images showed fusion and resolidification of the dentin surface, with partial removal of debris on the specimens irradiated with the Nd:YAG laser and the diode laser, compared with controls. CONCLUSION: Both lasers promote morphologic changes and debris removal. These alterations of the dentin surface appeared to be more evident in the Nd:YAG laser group, but the diode laser group showed more uniform changes.     

Argon and Nd:YAG Lasers for Caries Prevention in Enamel

Abstract Objective: The aim of this study was to investigate the effect of Nd:YAG and argon laser irradiations on enamel demineralization after two different models to induce artificial caries. Background data: It is believed that the use of the high-intensity laser on the dental structure can lead to a more acid-resistant surface. Materials and methods: Twenty-one extracted human third molars were sectioned into tooth quarters. The quarters were distributed in three groups: Group I (control), untreated; Group II, Nd:YAG laser (60?mJ, 15?pps, 47.77?J/cm(2), 30?sec); and Group III, argon laser (250?mW, 12?J/cm(2), 48?sec). Tooth quarters from each group were subjected to two different demineralization models: cycle 1, a 14 day demineralization (pH 4.5; 6?h) and remineralization (pH 7.0; 18?h) solutions, 37°C and cycle 2, 48?h in demineralization solution (pH 4.5). Samples were prepared in slices (60-100?μm thick) to be evaluated under polarized light microscopy. Demineralization areas were measured (mm(2)) (n=11). Data were analyzed by ANOVA and Tukey's test (p<0.05). Results: Means followed by different letters are significantly different: 0.25 A (control, cycle 48?h); 0.18 AB (control, cycle 14 days); 0.17 AB (Nd:YAG, cycle 14 days); 0.14 BC (argon, cycle 48?h); 0.09 BC (Nd:YAG, cycle 48?h), and 0.06 C (argon, cycle 14 days). Conclusions: The argon laser was more effective for caries preventive treatment than Nd:YAG laser, showing a smaller demineralization area in enamel.     

Use of Nd:YAG laser in pancreatic resections with duodenal preservation in the dog

The trend in recent years for treatment of pancreatic carcinoma and occasionally for pancreatitis has been towards total pancreatectomy. The pancreas is also now being harvested for transplantation. Any operative technique that can reduce operating time, blood loss, and associated morbidity and mortality would be of tremendous advantage. The aim of this study was to undertake a total pancreatectomy using the Nd:YAG laser (wavelength 1,060 nm) with a helium neon laser (wavelength 628 nm) incorporated to provide a marker beam. The laser beam was passed into a 400 micron flexible glass fiber enclosed in a 2.5 mm polyethylene cannula, which also served as a conduit for coaxial CO2. The laser was operated in a continuous wave mode, and the fiber exit beam had a divergence of 10 degrees. For photocoagulation and tissue vaporization, peak powers of 50 W were used with 0.5-1 sec pulses. The total pancreatectomy using the Nd:YAG laser was performed in eight dogs, and ten dogs undergoing the conventional operative procedure served as controls. The findings indicate that the Nd:YAG laser could be used effectively and safely. The operating time was considerably diminished (P less than 0.01); the number of ligatures used was smaller; blood loss, graft survival, and duodenal viability were similar. The Nd:YAG laser offers a new therapeutic modality in the performance of tedious and often difficult pancreatic surgery.     

Effect of HeNe and pulsed Nd:YAG laser irradiation on intradental nerve responses to mechanical stimulation of dentine

BACKGROUND AND OBJECTIVE: Our study aimed to determine how lasing affected intradental nerve responses to dentine stimulation. Study Design/Materials and Methods Intradental nerve activity was recorded from canine teeth of anaesthetised ferrets. Dentine exposed at the tip of the tooth was stimulated with a glass probe. After determining baseline responses to mechanical stimulation, dentine was lased using a pulsed Nd:YAG laser at 60-150mJ/pulse and 10-30 pulses/sec (total power = 0.3-3.0 W). RESULTS: The HeNe aiming beam alone and Nd:YAG laser at 0.3 W (+ HeNe) had no effect on intradental nerve responses to dentine stimulation. Lasing at 0.6-1. 5 W could either enhance or suppress intradental nerve responses. Lasing at more than or equal to 2.0 W or repeated lasing at lower intensities depressed intradental nerve responses. Lasing often induced intradental nerve firing. CONCLUSION: HeNe lasing had no effect on intradental nerve excitability. The Nd:YAG laser could depress intradental nerve responses to dentine stimulation.     

Nd:YAG laser versus traditional scalpel. A preliminary histological analysis of specimens from the human oral mucosa

Hyperplastic fibro-epithelial lesions are the most common tumor-like swellings in the mouth. The neodymium yttrium aluminium garnet (Nd:YAG) laser appears to be useful for the surgical treatment of these lesions. Some controversies of laser surgery concern the accuracy of pathological diagnosis as well as the control of thermal damage on the target tissue. The aim of this study was to establish if the thermal changes induced by the Nd:YAG laser may affect the histopathological diagnosis and the evaluation of the resection margins. Furthermore, we compared the histological features of oral benign fibro-epithelial lesions excised through Nd:YAG laser and traditional scalpel. Twenty-six benign fibro-epithelial oral lesions from 26 patients, localized in the same oral subsites (cheek and buccal mucosa), were collected at the Unit of Oral Pathology and Oral Laser-assisted Surgery of the Academic Hospital of the University of Parma, Italy. Specimens were subclassified into three groups according to the tool used for the surgical excision. Group 1 included six specimens excised through Nd:YAG laser with an output power of 3.5 W and a frequency of 60 Hz (power density 488,281 W/cm²); Group 2 included nine specimens excised through Nd:YAG laser with an output power of 5 W and a frequency of 30 Hz; Group 3 included 11 specimens excised through a Bard-Parker scalpel blade no. 15c. Epithelial changes, connective tissue modifications, presence of vascular modifications, incision morphology and the overall width of tissue modification were evaluated. Differences between specimens removed with two different parameters of Nd:YAG laser were not significant with regard to stromal changes (p = 0.4828) and vascular stasis (p = 0.2104). Analysis of regularity of incision revealed a difference which was not statistically significant (p = 1.000) between group 1 and group 2. Epithelial and stromal changes were significantly more frequent in specimens with a mean size less than 7 mm (p < 0.0001). Nd:YAG laser induced serious thermal effects in small specimens (mean size less than 7 mm) independently from the frequency and power employed. The quality of incision was better and the width of overall tissue injuries was less in the specimens obtained with higher frequency and lower power (group 1: Nd:YAG laser at 3.5 W and 60 Hz).