Yttrium Aluminum Garnet Laser Ablation Research Articles

Adhesion Properties of an Apatite Film Deposited on Dentine Using Er:YAG Laser Ablation Method

Tooth enamel cannot be naturally reconstructed once it is destroyed immoderately. Therefore, the restoration of enamel is important in dental treatment. Hydroxyapatite (HAp) can potentially be used for a novel dental biomaterial to repair the enamel. We have proposed a tooth restoration technique with intraoral laser ablation method. A thin layer of HAp was deposited on dentin surface in the atmosphere by ablation phenomenon using an Er:YAG (Erbium: Yttrium-Aluminum-Garnet) laser irradiated to the target of α-tricalcium phosphate (α-TCP). Then, the deposited layer was hydrolyzed by dripping pure water on its surface in order to create HAp film. The adhesive strength between the HAp film and dentin was evaluated by quasi-static tensile tests. As a result of the mechanical evaluation, the adhesive strength was greater than approximately 3.8 MPa. It is clear that the HAp film created by the Er:YAG laser ablation method is attached tightly to the dentin.

Flexible Cystoscopy and Holmium:Yttrium Aluminum Garnet Laser Ablation for Recurrent Nonmuscle Invasive Bladder Carcinoma Under Local Anesthesia

The management of recurrent nonmuscle invasive bladder cancer (NMIBC) post-transurethral resection has been based around electrocautery techniques, either under local or general anesthetic. We determine the long-term outcome of the management of NMIBC recurrences treated with Holmium:Yttrium Aluminum Garnet (Ho:YAG) laser ablation under local anesthetic with a flexible cystoscope. We performed a prospective analysis of 151 consecutive patients, undergoing treatment of 444 tumors, between 2006 and 2011 in a University Teaching Hospital. Median follow-up was 24 months (0-58 months). The primary outcome was local, on-site recurrence rates of NMIBC. The secondary outcome measure included off-site recurrence rates, complications, pain perception, and patient satisfaction. Local, on-site recurrence rates after first treatment for all NMIBC disease were 10%. In patients with low risk NMIBC (G1/2, Ta), this reduced to around 4% post laser treatment. Higher recurrence rates (14%) were seen in those with high-grade (G3, T1) disease. Treatment was more successful with disease around the trigone, posterior and lateral bladder walls, with a significantly higher risk of recurrence for tumor around the ureteric orifice. The median time to local recurrence was 12 months and off-site recurrence was 25 months. Complication rates were low: dysuria (4.2%), frequency (1.5%), and hematuria (1.9%), with no episodes of bladder perforation. Visual analog pain scores were low, mean score 1 (range 0-7). The overall patient satisfaction was 100%. Flexible cystoscopy and Ho:YAG laser therapy should be considered as a first line treatment option for the management of recurrence in low-grade NMIBC (G1/2, Ta/1) throughout the bladder, except around the ureteric orifices. For those with high-grade disease (G3), the recurrences rates are increased, but the procedure still offers an acceptable recurrence rate. It provides good local disease control, low complications, patient acceptability and tolerance.

Sebaceous hyperplasia

Sebaceous hyperplasia is a benign proliferation of sebaceous glands. These benign lesions can be found throughout the integument, but have a greater tendency to occur on the face, upper neck and chest. The use of dermatoscopy helps in the differentiation of these lesions from other disorders, such as molluscum contagiosum, sebaceous adenoma, sebaceous carcinoma and, most importantly, basal cell carcinoma. Multiple pathophysical pathways may play a role in the evolution of sebaceous hyperplasia. Better understanding of the multiple signaling molecules and hormonal changes may lead to less painful and more permanent treatment of these benign lesions that may be troubling to those affected. Current treatment includes shave excision, isotretinoin therapy, bichloroacetic acid, cryotherapy, carbon dioxide laser ablation, electrodessication, erbium or yttrium aluminum garnet laser ablation and pulsed-dye laser photothermolysis.

High Dose-Rate Endobronchial Radiotherapy for Proximal Airway Obstruction Due to Lung Cancer: 8-Year Experience of a Referral Center

The efficacy of high dose-rate endobronchial radiotherapy (HDERT) against proximal airway obstruction that results from lung cancer has not been thoroughly evaluated. This study retrospectively reviewed tumor/obstruction characteristics prior to therapy, interventions applied, symptoms before and after intervention, complications, and survival of all patients with proximal airway obstruction resulting from lung cancer who received HDERT between 1995 and 2003 in a tertiary teaching center. Thirty-four (34) patients received HDERT, while 28 had additional treatment (external radiotherapy = 23, neodymium yttrium aluminum garnet laser ablation = 9, stenting = 7, electrosurgery = 5, cryosurgery = 3, and photodynamic therapy = 1). Sixteen (16) patients developed complications, the most frequent being respiratory failure and bronchial-wall necrosis, while 19 experienced symptomatic relief. The median (95% confidence interval) survival of these 34 patients was 7.8 (5.9-9.8) months, significantly longer (p = 0.004) than a historic control of 3.9 (3.7-7.1) months from the Cleveland Clinic Foundation, in Cleveland, OH, and comparable to other previous reports. No single factor predicted complications or symptomatic relief. However, female gender, presence of only one symptom, absence of fatigue/weight loss, >1 HDERT sessions, and postprocedure symptom relief were associated with improved survival. Contemporary HDERT with or without additional treatment modalities is effective against central airway compromise resulting from lung cancer.

The influence of erbium:yttrium–aluminum–garnet laser ablation with variable pulse width on morphology and microleakage of composite restorations

The objective of this study was to evaluate the influence of various pulse widths with different energy parameters of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mum) on the morphology and microleakage of cavities restored with composite resin. Identically sized class V cavities were prepared on the buccal surfaces of 54 bovine teeth by high-speed drill (n = 6, control, group 1) and prepared by Er:YAG laser (Fidelis 320A, Fotona, Slovenia) with irradiation parameters of 350 mJ/ 4 Hz or 400 mJ/2 Hz and pulse width: group 2, very short pulse (VSP); group 3, short pulse (SP); group 4, long pulse (LP); group 5, very long pulse (VLP). All cavities were filled with composite resin (Z-250-3 M), stored at 37 degrees C in distilled water, polished after 24 h, and thermally stressed (700 cycles/5-55 degrees C). The teeth were impermeabilized, immersed in 50% silver nitrate solution for 8 h, sectioned longitudinally, and exposed to Photoflood light for 10 min to reveal the stain. The leakage was evaluated under stereomicroscope by three different examiners, in a double-blind fashion, and scored (0-3). The results were analyzed by Kruskal-Wallis test (P > 0.05) and showed that there was no significant differences between the groups tested. Under scanning electron microscopy (SEM) the morphology of the cavities prepared by laser showed irregular enamel margins and dentin internal walls, and a more conservative pattern than that of conventional cavities. The different power settings and pulse widths of Er:YAG laser in cavity preparation had no influence on microleakage of composite resin restorations.

The vibrational spectrum of fanlike ScC3 in solid Ar

Fourier transform infrared spectra of fanlike (C(2v)) ScC(3) have been obtained by trapping the vapor from the Nd:YAG (yttrium aluminum garnet) laser ablation of (13)C-enriched graphite and Sc rods in solid Ar at approximately 10 K. Three vibrational fundamentals, the nu(5)(b(2))=1478.0 cm(-1) asymmetric carbon stretch, the nu(3)(a(1))=557.0 cm(-1) symmetric metal-carbon stretch, and the nu(1)(a(1))=1190.7 cm(-1) symmetric carbon stretch have been observed for the first time. The measured isotopic spectra are in good agreement with DFT-B3LYP/6-311G(3df,3pd) simulated spectra and indicate a (2)A(2) ground state rather than (4)B(1) as suggested by other theoretical calculations. The frequency of the nu(3)(a(1)) fundamental is consistent with a frequency of 560+/-30 cm(-1) reported in a photoelectron spectroscopy investigation of ScC(3).

Efficacy of percutaneous treatment of biliary tract calculi using the holmium:YAG laser

Few Western studies have focused on percutaneous techniques using percutaneous transhepatic choledochoscopy (PTHC) and holmium:yttrium-aluminum-garnet (YAG) laser to ablate biliary calculi in patients unable or unwilling to undergo endoscopic or surgical removal of the calculi. The authors report the efficacy of the holmium:YAG laser in clearing complex biliary calculi using percutaneous access techniques. This study retrospectively reviewed 13 non-Asian patients with complex secondary biliary calculi treated percutaneously using holmium:YAG laser. Percutaneous access was accomplished via left, right, or bilateral hepatic ducts and upsized for passage of a 7-Fr video choledochoscope. Lithotripsy was performed under choledochoscopic vision using a holmium:YAG laser with 200- or 365-microm fibers generating 0.6 to 1.0 joules at 8 to 15 Hz. Patients underwent treatment until stone clearance was confirmed by PTHC. Downsizing and subsequent removal of percutaneous catheters completed the treatment course. Seven men and six women with an average age of 69 years underwent treatment. All the patients had their biliary tract stones cleared successfully. Of the 13 patients, 3 were treated solely as outpatients. The average length of percutaneous access was 108 days. At this writing, one patient still has a catheter in place. The average number of holmium:YAG laser treatments required for stone clearance was 1.6, with no patients requiring more than 3 treatments. Of the 13 patients, 8 underwent a single holmium:YAG laser treatment to clear their calculi. Prior unsuccessful attempts at endoscopic removal of the calculi had been experienced by 7 of the 13 patients. Five patients underwent percutaneous access and subsequent stone removal as their sole therapy for biliary stones. Five patients were cleared of their calculi after percutaneous laser ablation of large stones and percutaneous basket retrieval of the remaining stone fragments. There was one complication of pain requiring admission, and no deaths. The use of PTHC with holmium:YAG laser ablation is safe and efficacious, but requires prolonged biliary access and often multiple procedures to ensure clearance of all calculi.

Structural and bonding properties of carbon nitride films synthesized by low energy nitrogen-ion-beam-assisted pulsed laser deposition with different laser fluences

Carbon nitride films were deposited by pulsed Nd:yttrium–aluminum–garnet laser ablation of graphite with assistance of low energy nitrogen-ion-beam bombardment. The nitrogen to carbon (N/C) atomic ratio, surface morphology, bonding state, and microstructure of the deposited carbon nitride films were characterized by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy, atomic force microscopy (AFM), and x-ray diffraction. The influence of laser fluence on the synthesis of carbon nitride films was investigated. The N/C atomic ratio of the carbon nitride films can reach the maximum at the highest laser fluence. XPS and FTIR analyses indicated that the bonding state between the carbon and nitrogen in the deposited films was significantly influenced by the laser fluence during deposition. The carbon–nitrogen bonding of C–N and C=N were observed in the films. In addition, α and β C3N4 phases were found to coexist in the carbon nitride films with relative low degree of ordering in the crystal lattice. AFM results indicated that the laser fluence also had a critical effect on the surface structure of the carbon nitride films.

Use of the holmium yttrium aluminum garnet laser for percutaneous thoracolumbar intervertebral disk ablation in dogs

Objective To evaluate a laser ablation technique for treatment of thoracolumbar intervertebral disk disease in dogs. Design Prospective case series. Animals 33 dogs with signs of recurrent back pain associated with intervertebral disk disease after the initial episode had been managed conservatively for a minimum of 2 weeks. Procedure Spinal needles were placed percutaneously through the annulus fibroses to permit delivery of an optical fiber into the nucleus pulposes of thoracolumbar intervertebral disks T10-11 through L3-4. Fluoroscopy was used to guide needle placement. Holmium yttrium aluminum garnet laser energy then was used to ablate the contents of each selected intervertebral disk. Intervals from time of treatment to time of assessment ranged from 3 to 114 weeks. Results All dogs recovered without complication. Results of follow-up radiography and histologic evaluation indicated that percutaneous holmium yttrium aluminum garnet laser ablation reduces the volume of nucleus pulposus in treated disks. Clinical Implications Used as a clinical treatment and prophylactically, this minimally invasive procedure should prevent further extrusion of partially herniated disks and should reduce the chances of subsequent herniation of disks at other treatment sites. (J Am Vet Med Assoc 1996;208:1263–1267)

In vitro study of ablated lung tissue in Nd:YAG laser irradiation

Neodymium:yttrium-aluminum garnet lasers are used to reduce lung volume. An assessment of the relationship between the histologic and gross findings in the lung irradiated by a laser would be helpful in laser-assisted pneumoplastic procedures. In vitro lung lobes surgically resected for pulmonary carcinomas were irradiated with a neodymium:yttrium-aluminum garnet laser at three energy levels in three modes: contact rubbing, contact pointing, and noncontact. Pleural degeneration in 216 samples from 24 lobes was classified as coagulative, amorphous, or destructive. At all energy levels, the laser was applied for 1.5 seconds. Noncontact mode at 7.5 W or 15 W and contact rubbing at 5 W caused coagulative or amorphous degeneration but no destructive degeneration. The energy level correlated with the color of the degenerated pleura. The incidence of destructive pleural degeneration, which led to air leaks as revealed by an air inflation test, was 0% in pink and white samples, 59% in brown samples, and 100% in black samples (p < 0.0001, white versus brown samples). In neodymium:yttrium-aluminum garnet laser ablation of lung tissue, the color of the degenerated pleura correlates with the intensity of the applied laser energy and the degree of pleural degeneration.

Superconducting thin films of Y-Ba-Cu-O produced by neodymium:yttrium aluminum garnet laser ablation

Superconducting thin films of Y-Ba-Cu-O produced by laser ablation of nonsuperconducting targets by 1064 nm neodymium:yttrium aluminum garnet radiation in an oxygen ambient are described. Deposition rates of 100 Å/s were achieved for 1 J pulses at 30 Hz. Scanning Auger microscopy indicates phase segregated films. Optical probing of ablated flux suggests it consists of atomic and molecular fragments.