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PubMed1995

Prevention of pharyngocutaneous fistulas by means of laser-weld techniques.

Although much has been written on methods of dealing with pharyngocutaneous fistulas once they have formed, there are few reports of methods of preventing fistula formation from occurring. We examined the use of laser-weld techniques with the neodymium:yttrium aluminum garnet (Nd:YAG) and diode lasers to seal pharyngotomy closures. Laser-weld techniques have been used successfully in many other tissues, but reports documenting use in the upper aerodigestive tract are minimal. Indocyanine-green dye-enhanced collagen and fibrinogen were studied as laser solder materials for the diode laser. Twenty-nine experimental animals were studied. Neither the Nd:YAG nor the diode laser was successful in preventing fistula formation. Tensiometric studies documented significant strength of the laser welds ex vivo, but this finding was not clinically significant.

Anastomosis, Surgical↗
PubMed2006

Bowel welding technique in dogs and cats using a diode laser: an experimental study.

A laser bowel welding technique for dogs and cats was developed. The bowel was pinched using a special clamp having an opening on the body developed for this experiment (LW clamp). Using the 2 different types of contact probe (blunt tip: Laser Bipolar Dissector (LBD); sharp tip: Super Scalpel Dissector (SSD)), the laser passed through the hole in the LW clamp to cut the bowels, while at the same time, sealing the cut portion. The results obtained in this study showed that the optimum laser output using LBD was 6-10 W in dog and cat ileum, and 8-10 W in dog and cat colon. Optimum laser output using SSD was 6-8 W in dog ileum, 8-10 W in dog colon, 10 W in cat ileum and 6-8 W in cat colon. No marked differences were observed between ileum and colon when using either LBD or SSD. At the same power, burst pressure tended to be slightly higher with LBD than with SSD, although there were not significant differences between them. Histologically, complete sealing of the welded site was seen. Welding and cutting of bowel in dogs and cats was thus confirmed to be possible using the LW clamp in combination with LBD or SSD probes under a diode laser output of approximately 8 W for 50-80 s (400-640 J/cm). Thus, we can expect that this method is applicable to clinical veterinary medicine.

Animals↗
PubMed2005

Optical techniques for real-time penetration monitoring for laser welding.

Optical techniques for real-time full-penetration monitoring for Nd:YAG laser welding have been investigated. Coaxial light emission from the keyhole is imaged onto three photodiodes and a camera. We describe the spectral and statistical analyses from photodiode signals, which indicate the presence of a full penetration. Two image processing techniques based on the keyhole shape recognition and the keyhole image intensity profile along the welding path are presented. An intensity ratio parameter is used to determine the extent of opening at the rear of a fully opened keyhole. We show that this parameter clearly interprets a hole in formation or a lack of penetration when welding is performed on workpieces with variable thicknesses at constant laser power.

Journal Article↗
PubMedDate not supplied

Immediate implant-supported oral rehabilitation using a photocurable plastic skull model and laser welding. A technical note on the screw-retained type: Part 1.

PURPOSE: This article describes a new procedure for immediate implant-supported oral rehabilitation using a photocurable resin skull model and a laser-welding apparatus. MATERIALS AND METHODS: Preoperatively, the framework was fabricated on a photocurable resin skull model produced from a CT scan and individually designed guide template. The implants were immediately placed using the guide template; laser welding connected the components of framework. RESULTS: Despite the custom-made prosthesis, the total treatment from implant placement to superstructure placement can be completed within only 1 day. CONCLUSION: This procedure for immediate implant-supported oral rehabilitation using a photocurable resin skull model and a laser-welding apparatus may be useful for any implant system and patient.

Dental Articulators↗
PubMedDate not supplied

Implant-supported welded titanium frameworks in the edentulous maxilla: a 5-year prospective multicenter study.

PURPOSE: This study evaluated the 5-year clinical and radiographic performance of fixed implant-supported maxillary prostheses with either welded titanium or conventional cast-gold alloy frameworks. MATERIALS AND METHODS: Fifty-eight consecutive patients were provided with 349 osseointegrated Brånemark system implants in the edentulous maxilla at six different implant centers. Twenty-eight of the patients received, at random, prostheses with laser-welded titanium frameworks, and the remaining 30 patients had prostheses with conventional cast-gold alloy frameworks. Clinical and radiographic data were collected for 5 years after prosthesis placement. RESULTS: The titanium and cast-gold framework groups exhibited similar cumulative survival and success rates (CSR). The 5-year implant CSR from time of placement was 91.4% and 94.0%, respectively, and from prosthesis delivery the rate was 94.9% and 95.6%, respectively. The corresponding 5-year prosthesis CSRs were 96.4% and 93.3%. One patient from each group lost all the implants and turned to complete dentures within the first year of function. Another patient with a cast-gold framework had the prosthesis replaced after 4 years, basically because of problems with the veneering material. No fractures of implant components were observed during the follow-up period. Bone loss was on average 0.59 mm (SD 0.97 mm) during 5 years, with no statistical difference between the two groups. CONCLUSION: Welded titanium frameworks presented a similar favorable clinical performance as conventional cast-gold alloy frameworks in fixed implant-supported prostheses in the edentulous maxilla after 5 years in function. Implant failures were concentrated in only a few patients in each study group.

Adult↗
PubMed1998

[Dental welding titanium and its clinical usage].

Due to its excellent biocompatibility, desirable chemical and mechanical properties, Titanium has been used for implant denture, RPD and FPD, where welding techniques were indispensable. This paper introduces 5 useful modern ways to weld Titanium and their clinical usage. They are: laser, plasma welding, TIG, infraned brazing and Hruska electrowelding.

Dental Soldering↗
PubMedDate not supplied

Implant-supported laser-welded titanium and conventional cast frameworks in the partially edentulous law: a 5-year prospective multicenter study.

PURPOSE: This study evaluated and compared the clinical performance of laser-welded titanium fixed partial implant-supported prostheses with that of conventional cast frameworks in the partially edentulous jaw. MATERIALS AND METHODS: Forty-two patients provided with Brånemark system implants were arranged into two groups. Twenty-one patients (group A) were provided with a conventional cast ceramometal framework in one side of the jaw and a laser-welded titanium framework with low-fusing porcelain in the other side. In group B, 21 patients received a titanium framework prosthesis to replace a conventional implant prosthesis. Clinical and radiographic data were collected for 5 years. RESULTS: Four implants and one titanium framework were lost during the follow-up period. The two framework designs did not show any significant differences with regard to implant or prosthesis survival (P > .05). Few clinical complications were observed. In group A, marginal bone loss after 5 years was similar for both prosthesis designs, with an average of 0.1 mm and 0.3 mm in the maxilla and mandible, respectively. Basically, no bone loss was observed on average in group B. Furthermore, no significant relationship was observed between marginal bone loss and placement of prosthesis margin or prosthesis design. CONCLUSION: Except for an insignificant tendency toward a slightly higher incidence of small chips of porcelain veneers, laser-welded titanium frameworks presented an overall similar clinical performance as conventional cast frameworks in partial implant situations after 5 years.

Adult↗
PubMed2004

[Experimental substantiation of the method of biological tissue welding in surgical hepatology].

Application of the welding method for biological tissues in hepatobiliary surgery was experimentally substantiated. In 14 pigs (25-30 kg body mass) resection of one hepatic lobe, using electric welding method, was done. In control group (4 pigs) the similar operative intervention was accomplished, using conventional method. Application of the electric welding method guarantees secure hemostasis and cholestasis, do not causes specific pathological changes in the adjacent region of affection tissues, speed of restoration of the structures damaged exceeds such in application of the suturing method.

Animals↗
PubMed1992

Evaluation of the CO2 laser for endodontic root apex welding.

A low-wattage carbon dioxide laser was tested as a means of welding (sealing) the apices of unfilled, endodontically prepared teeth. Thirty-five teeth were filed and lased using a variety of power settings. Apical seals were examined microscopically, radiographically, and mechanically for complete welds. Accurately directed laser exposures of 15 or more watts with a 0.5 second duration will completely seal the apical openings of anterior teeth. The ideal treatment for endodontically compromised teeth has always been a completely sealed tooth apex. Usually amalgam, gutta-percha, or resin sealers are used after a lengthy and tedious preparation of the exposed root area. The carbon dioxide laser is designed for soft tissue dental surgery but is capable of melting enamel and dentin which recrystallizes in a dense solid as it cools (fig. 1). The laser, with its potential for accurately delivering a great quantity of energy to a small, exposed surface, appears to be an excellent tool for quick, direct sealing of open apices. This paper will investigate the practicality and best methods of spot welding root apices.

Humans↗
PubMed2006

[Pulmonary tissue welding--the method of nonresectional intervention for spontaneous pneumothorax].

New method of the viable tissues welding was applied for spontaneous pneumothorax treatment. There was presented first experience of pulmonary tissue welding without its resection. Since January, 2005 there were performed 17 operations of restricted thoracotomy in randomly selected patients with spontaneous pneumothorax. During the operation there were revealed solitary disseminated bullas in 4 (23.5%) observations, intrapulmonary and superficial--in 8 (47%), thin-wall bullas conglomerate--in 5 (29.5%). In 6 patients up to the operation performance the air passage was preserved. In all the patients the parts of emphysematously changed pulmonary tissue were processed using bipolar set up of original construction. In all the patients there were achieved the bullas electroablation and pulmonary tissue closure without usage of suturing devices or manual suturing. The pneumothorax recurrence, bleeding, durable passage of air, infection complications were not observed. The authors consider the method of emphysematously changed tissue welding a secure one in treatment of spontaneous pneumothorax, omitting pulmonary tissue resection.

Adolescent↗
PubMed1991

Tissue welding with lasers.

Over the last several years, several exciting developments have occurred that may facilitate the use of the laser in reconstructive surgery. The goal of future research should be to make the procedure less operator-dependent (dye enhanced or automated welding). Another avenue of research would be to give the operator instantaneous feedback to assess parameters at the weld site to allow modification of the energy delivered. Currently, only color change of the tissue and experience provide the endpoints. With future research into these and other areas, laser welding continues to hold promise to become a useful adjunct in reconstructive surgery.

Animals↗
PubMedDate not supplied

[Application of the technic of laser welding to creation of extra-intracranial microanastomoses].

A method for joining vessels by means of argon laser, i. e. by "laser welding" was developed. It was proved in experiment that endothelium formation is more adequate in a vascular microsuture formed by laser welding than in the formed by the traditional thread method. Forty one operations for creating an extraintracranial microanastomosis were found by laser welding. The prospective clinical effect was positive in 36 patients. Control angiograms demonstrated good patency of the created microvascular anastomosis.

Adult↗
PubMed1997

Effect of laser wavelength and protein solder concentration on acute tissue repair using laser welding: initial results in a canine ureter model.

Successful tissue approximation can be performed using low power laser energy combined with human albumin solder. In vitro studies were undertaken to investigate the acute repair strengths achieved using different laser wavelengths. Furthermore, we evaluated the change in repair strength with that resulted from changes in protein solder concentration. Intraluminal bursting pressure following ureterotomy repair was measured for the following laser wavelengths: 532, 808, 1,320, 2,100, and 10,600 nm. The tissue absorption characteristics of the 808-nm diode and the KTP-532-nm lasers required the addition of the exogenous chromophores indocyanine green and fluorescein, respectively. A 40% human albumin solder was incorporated in the repair of a 1.0-cm longitudinal defect in the canine ureter. Following determination of an optimal welding wavelength, human albumin solder of varying concentrations (25%, 38%, 45%, and 50%) were prepared and tested. The 1,320-nm YAG laser achieved the highest acute bursting pressure and was the most effective in this model. Of the concentrations of albumin tested, 50% human albumin yielded the greatest bursting pressures. We conclude that of the laser wavelengths evaluated, the 1,320-nm YAG achieves the strongest tissue weld in the acute ex vivo dog ureter model. In addition, when this laser system is used, the acute strength of a photothermal weld appears to be directly proportional to the concentration of human albumin solder in the range of 25 to 50%.

Albumins↗
PubMed1987

Bronchocarcinogenic properties of welding and thermal spraying fumes containing chromium in the rat.

The possible bronchocarcinogenic effects of fumes released during the shielded metal arc welding of stainless steel and the thermal spraying of chromium oxide (Cr2O3) have been studied on the rat. The fume particles were shown to contain tri- and hexavalent chromium in soluble and low soluble forms; they were collected and implanted as pellets in the bronchi of groups of 100 rats by the method of Laskin et al. A negative control group of 100 rats was included, as well as positive controls receiving pellets containing benz(a)pyrene. The experiment was continued for 34 months; no differences of biological significance were noted between the growth rates, survival times, and terminal organ weights of the test and negative control groups. At autopsy, the macroscopic and microscopic appearance of the organs in the three groups, including the local reaction to the implanted pellet, were similar. No precancerous changes were observed at the implantation sites; one rat, who received a pellet containing welding fumes, showed squamous cell carcinoma remote from the implantation site and not associated with the bronchus. It had the appearance of a metastasis. All three benz(a)pyrene control rats developed cancer at the implantation site. The occupational health implications of these findings are discussed.

Air Pollutants, Occupational↗
PubMed1992

Hard metal interstitial pulmonary disease associated with a form of welding in a metal parts coating plant.

We describe two cases of hard metal pulmonary disease (one fatal) in workers employed in the same area of a metal coating plant using the detonation gun process for applying a durable metal surface to metal parts. In this form of welding, a mixture of powdered metals, including tungsten carbide and cobalt, is heated by ignition of a flammable gas and propelled from the end of the "gun" at high temperature and velocity to form a welded metal coating. This process is done in an enclosed chamber and with each application, large volumes of fine aerosols are created. Inhalation exposure to hard metal may occur during the mounting and removal of the metal parts between applications, in spite of engineering controls and industrial hygiene surveillance. One of the cases presented with minimal chest x-ray abnormalities and an obstructive pattern on pulmonary function testing, although subsequent open lung biopsy showed diffuse interstitial pulmonary fibrosis. The fact that two cases of hard metal pulmonary interstitial disease occurred where thorough exposure control procedures and a surveillance program for cobalt were in place may indicate the need for revisions of the current technology used when hard metal is applied in the detonation gun process.

Adult↗
PubMed2006

Assessment of occupational exposure to welding fumes by inductively coupled plasma-mass spectroscopy and by the alkaline Comet assay.

Welding fumes are classified as possibly carcinogenic to humans (Group 2B) by the International Agency for Research on Cancer. In the current study, blood and urine concentrations of aluminum (Al), cadmium (Cd), cobalt (Co), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were monitored by inductively coupled plasma-mass spectrometry (ICP-MS) in 30 welders and in 22 controls. In addition, DNA damage was examined in the lymphocytes of these subjects by the alkaline Comet assay. Two biological samples were taken from the welders at the beginning (BW) and at the end (EW) of a work week. In controls, collection of samples was limited to BW. Blood concentrations of Cd, Co, Cr, Ni, and Pb were higher in the welders than in the control group while higher concentrations of Al, Cd, Co, Cr, Ni, and Pb were detected in welder urines. There was no significant difference in the metal concentrations for the BW and EW welder samples. Increased levels of DNA damage were found in lymphocytes from welders as compared to the controls, and 20/30 welders had higher levels of DNA lesions in the EW than in the BW samples. Age had a significant effect on DNA damage in the control group. Spearman's rank correlation analysis indicated that there were positive correlations between blood concentrations of Al, Co, Ni, and Pb and the levels of DNA damage. A negative correlation was found between DNA damage and Mn in blood, while there was a positive correlation between urinary Mn concentration and DNA damage. These data indicate that occupational exposure to welding fumes increases DNA damage in lymphocytes.

Adult↗
PubMed2002

Tissue welding with biodegradable polymer films-demonstration of acute strength reinforcement in vivo.

BACKGROUND AND OBJECTIVES: To demonstrate, in vivo, acute strength reinforcement benefits of polymer film patches. STUDY DESIGN/MATERIALS AND METHODS: Full thickness incisions created in a dorsal skin flap of Sprague-Dawley rats were closed by laser-tissue welding: albumin solder was topically applied to the incision on the dermal surface, and a poly(lactic-co-glycolic acid) (PLGA) polymer film placed on the solder as a patch (controls had no film). Breaking strength was tested acutely (15-20 minutes after sacrifice). RESULTS: The patched incisions were statistically stronger than the controls (ANOVA, P < 0.05). CONCLUSIONS: Polymer film patches may be a viable method to increase acute breaking strengths of welds using topically applied solder.

Animals↗
PubMed1984

Pneumoconiotic effects of welding-fume particles from mild and stainless steel deposited in the lung of the rat.

Rats were exposed to single periods of inhalation of fumes generated by arc welding. Two processes were compared: either manual metal arc (MMA) using flux-coated mild steel (MS) electrodes or metal inert-gas (MIG) welding with stainless steel (SS). Widespread but small deposits of fume particles were cleared effectively from alveoli and airways. Peribronchial and subpleural aggregates of particle-laden macrophages remained. More massive and persistent lung-burdens were established by intratracheal administration of suspensions of fume-particles (10 mg and 50 mg, single doses). Initial pneumonitis was attributed to irritant gases or soluble toxic components of particles. MIG-SS particle deposits were more persistent and lesions more severe, inhibition of phagocytosis or clearance and damage to epithelial cells being associated with possible toxic effects in macrophages. Both types of particle caused alveolar epithelial thickening, with proliferation of granular pneumocytes and exudation of lamellar material. Foam cells appeared in alveoli. Long-term effects (80-300 days) involved formation of nodular aggregates of particle-laden macrophages. Giant cells were formed. Nodules containing MIG-SS material were irregular and surrounded by collapsed and thickened epithelium. Soluble chromium or nickel constituents are cited as probable active agents producing effects resembling those of cytotoxic non-fibrogenic dusts, e.g., soluble silicas . MMA-MS particles produced low-grade fibrotic ( collagenised ) changes.

Acute Disease↗