For an effective Doppler Global Velocimeter (DGV), there is a requirement to accurately record and tune the frequency content of the laser used. The laser used for this experiment was an ND:YAG. Adjusting the mean frequency of the ND:YAG is accomplished by controlling the seed laser diode output, which also narrows the bandwidth of the laser to below 20 MHz. The exact frequency of operation is critical for the operation of the system. Standard interferometry techniques that measure laser frequency content, such as Fabre-Perot and grating based systems, are not able to provide an adequate spectrum resolution for the 9 ns pulse duration of the ND:YAG laser. A method was developed that employs a CCD line camera and a laser reference cell to effectively and cost efficiently solve this problem. The hardware and software for this real time monitoring system were developed and used with a real time feedback loop to stabilize the laser operating frequency at a specified value. The receiving optics of this DGV system were upgraded with 12 bit CCD cameras and a temperature controlled laser reference cell to decrease the uncertainty to the velocity measurement from over 4 m/s to less than 1 m/s. Recommendations to the effectiveness of the system and future improvements are provided.

The rapid developments in optical and electronic technologies have accelerated developments of solid state laser technology. The diode-pumped solid state laser has the merits of the diode laser, such as compactness, low cost, and the merits of the solid state laser, such as high laser quality, high conversion efficiency, long lifetime, and simple structure. There use in laser applications is very cost-effective in terms of material consumption, which is typically one-thousandth that of bulk material. In addition, heat dissipation in the gain medium can be significantly alleviated because highly heat-conductive material can be applied to the circumference of the crystal fiber. So, it was applicated in electronics, communication and medicine widely. The laser-heated pedestal growth (LHPG) method is now a well-established technique for the growth of single-crystal fibers. It is crucible free and can therefore produce high-purity, low-defect-density single crystals. Interface loss is one of the dominant factors that reduce the efficiency of crystal fiber lasers, although cladding with a dielectric coating or in-diffusion of the gain core has been utilized to suppress this interface loss. Using a gradient-index Nd:YAG crystal fiber with peak Nd concentration up to 1.6-atm.%, we recently demonstrated a laser power of 145 mW and slope efficiency 28.9%. Peak Nd concentration up to 3.6-atm.% Nd:YAG crystal fiber with a 20-um core was grown, which could eliminate the interface loss and enhance the efficiency of crystal fiber lasers to be compatible with bulk solid-state lasers.

Vários experimentos têm demonstrado que pulsos ultra curtos no domínio de subpicossegundos promovem uma combinação de efeitos termomecânicos que superam algumas das objeções ao uso de um laser como instrumento removedor. Usando os parâmetros apropriados de operação, lasers com pulsos ultra curtos podem se comportar melhor do que instrumentos convencionais, incluindo alguns dos lasers pulsados comercialmente já disponíveis na Odontologia. A exploração e otimização nos parâmetros dos lasers disponíveis podem promover a remoção de certas objeções ao amplo uso dos lasers. O uso de lasers de pulsos ultra-curtos para ablação de dentes previne o superaquecimento e é uma alternativa para a remoção mecânica de material; além de minimizar o volume desse material removido. Através de estudos morfológicos e químicos, são apresentadas as características de interação laser pulsado - tecido duro dental, com relação a sua largura de pulso - nano ou picossegundos. O objetivo principal é dar início a um novo sistema para ablação de esmalte e dentina humanos: o laser de Nd:YAG no regime de picossegundos. A eficiência da ablação com laser através de um regime de picossegundos minimiza a destruição do material adjacente devido a formação de plasma e ataque. Isso previne a geração excessiva de ondas de choque e promove uma considerável diminuição nos efeitos mecânicos. A diminuição das ondas de choque provavelmente também poderá reduzir a vibração e conseqüentemente a sensação de dor, se aplicado clinicamente. Apesar da baixa taxa de ablação, os resultados mostram a real possibilidade para usar um sistema laser comercial relativamente simples para pulsos em picossegundos que poderia promover a Dentística Operatória Puntual e Seletiva, em outras palavras, seria possível tratar apenas o tecido alterado com seletividade e sem remover tecido sadio ou mesmo promover danos aos tecidos ao redor. Na maioria dos experimentos aqui apresentados, o laser de pulso ultra-curtos apresentou aumento na proporção Ca/P, melhorando a resistência química da superfície irradiada. Além disso, os cortes precisos resultam em superfícies mais lisas, que é importante para prevenir a colonização do biofilme. Outros estudos in vitro são necessários, mudando os parâmetros de energia e simulando situações clínicas para propor o uso efetivo desse sistema in vivo, mas, de fato, o sistema laser em picossegundos pode melhorar a qualidade da Dentística Operatória num futuro breve. / In several already demonstrated experiments, ultrashort laser pulses on the subpicosecond range have been shown to produce a strong thermo-mechanical effect, in several different situations. Even been out side dentistry, the general aspects of subpicosecond pulses interaction with matter are of broad applications on can be used as general references. This strong thermo-mechanical effect has created objections toward the use of such lasers as a material removal too1. On the other hand, using the appropriated parameters of operation, ultra short laser pulses of subnanosecond duration could present better performance than conventional lasers operating at nanosecond regime in several aspects. Through chemical and morphological studies, they are presented the main features from interaction between pulsed laser and dental hard tissue, considering pulse width - nano or picosecond pulse. The main objective is starting to use a new system to ablate human enamel and dentin: Nd:YAG picosecond laser system. Efficient laser ablation in the picosecond regime minimizes destruction of adjacent material due to a plasma formation and etching. This avoids an excessive generation of shock waves and promotes a considerable decrease in mechanical effects. The decreasing of shock waves also reduces vibration and consequently the sensation of pain, if clinically used. Despite the small ablation rate, our results show the real possibility to use a relative simple commercial laser system for picosecond pulses to be use effectively in Dentistry. The real clinical use of a picosecond laser system could promote the Punctual and Selective Operative Dentistry, in other words, we could treat just the decayed tissue with selectivity without remove sound tissue or even promote damage to tissues around. Besides, the precise cuts maybe give us a smoother surface, which is important to prevent biofilm colonization. We need to evaluate more in vitro studies, changing parameters and simulating clinical situations to propose the effective use of this system in vivo, but in fact, we believe that the picosecond laser system can improve the quality of Operative Dentistry in a brief future.

As endotoxinas são responsáveis por importantes reações sistêmicas e locais, podendo comprometer o sucesso do tratamento endodôntico. O hidróxido de cálcio, mesmo com limitações, mostra-se como opção única efetiva entre as soluções irrigadoras e as medicações intracanal na redução das endotoxinas nos túbulos dentinários. O experimento realizado avaliou a eficiência do laser de Nd:YAG frente à uma endotoxina inoculada no canal radicular pela utilização de duas cinemáticas de irradiação. Após um período de incubação, confirmada a passagem da endotoxina inoculada no canal radicular através da dentina e do cemento radicular, a irradiação foi realizada ou com cinemática oscilatória ou com cinemática helicoidal, para posterior leitura e comparação com os grupos controle. Os parâmetros utilizados na irradiação com o laser de Nd:YAG de comprimento de onda de 1064 nm foram: 100mJ, 15 Hz, 1,5 W, diâmetro do núcleo da fibra 320 ?m, fluência do pulso 124 J/cm2, largura do pulso 120 ?s e intervalo de relaxação térmica 30 s. Os dados foram comparados pelo método ANOVA, complementado pelo teste de Tukey. As concentrações de endotoxina nos espécimes dos grupos irradiados (helicoidal e oscilatório) foram similares. Além disso, elas também foram similares às dos espécimes controle negativo e significantemente menores (p=0,0271) que as do controle positivo, que não sofreram irradiação. A irradiação com laser de Nd: YAG, nas condições deste experimento é efetiva na inativação da endotoxina da dentina radicular. / The endotoxins are responsible for important systemic and local reactions that could compromise the endodontic success. The calcium hydroxide even with limitations is the only effective option among the irrigant solutions and intracanal medications on the endotoxin reduction in the dentinal tubules. This experiment evaluated the Nd:YAG laser efficacy regarding the inoculated endotoxin in the root canal with two cinematic irradiation procedures. The irradiation was accomplished using an oscillatory and helicoidal technique after an incubation period where the passage of the inoculated endotoxin inside the root canal through dentin and cement was confirmed. Following this the analysis and comparison among the groups was performed. The Nd:YAG laser (?=1064 nm) irradiation, used parameters were: 100mJ, 15 Hz, 1,5 W, core fiber diameter of 320 ?m, pulse fluency of 124 J/cm2, pulse width of 120 ?s and relaxation time interval of 30 s. The data were statistically compared by ANOVA complemented by the Tukey\'s test (p<=0,005). The endotoxin concentration at the irradiated samples, regardless the techniques applied were similar. Moreover these concentrations were also similar to those of negative controls and significantly smaller than those of positive controls that were not irratiated (p=0,0271). The Nd:YAG laser irradiation under this experiment conditions was effective on the root canal endotoxin inactivation.

Vários experimentos têm demonstrado que pulsos ultra curtos no domínio de subpicossegundos promovem uma combinação de efeitos termomecânicos que superam algumas das objeções ao uso de um laser como instrumento removedor. Usando os parâmetros apropriados de operação, lasers com pulsos ultra curtos podem se comportar melhor do que instrumentos convencionais, incluindo alguns dos lasers pulsados comercialmente já disponíveis na Odontologia. A exploração e otimização nos parâmetros dos lasers disponíveis podem promover a remoção de certas objeções ao amplo uso dos lasers. O uso de lasers de pulsos ultra-curtos para ablação de dentes previne o superaquecimento e é uma alternativa para a remoção mecânica de material; além de minimizar o volume desse material removido. Através de estudos morfológicos e químicos, são apresentadas as características de interação laser pulsado - tecido duro dental, com relação a sua largura de pulso - nano ou picossegundos. O objetivo principal é dar início a um novo sistema para ablação de esmalte e dentina humanos: o laser de Nd:YAG no regime de picossegundos. A eficiência da ablação com laser através de um regime de picossegundos minimiza a destruição do material adjacente devido a formação de plasma e ataque. Isso previne a geração excessiva de ondas de choque e promove uma considerável diminuição nos efeitos mecânicos. A diminuição das ondas de choque provavelmente também poderá reduzir a vibração e conseqüentemente a sensação de dor, se aplicado clinicamente. Apesar da baixa taxa de ablação, os resultados mostram a real possibilidade para usar um sistema laser comercial relativamente simples para pulsos em picossegundos que poderia promover a Dentística Operatória Puntual e Seletiva, em outras palavras, seria possível tratar apenas o tecido alterado com seletividade e sem remover tecido sadio ou mesmo promover danos aos tecidos ao redor. Na maioria dos experimentos aqui apresentados, o laser de pulso ultra-curtos apresentou aumento na proporção Ca/P, melhorando a resistência química da superfície irradiada. Além disso, os cortes precisos resultam em superfícies mais lisas, que é importante para prevenir a colonização do biofilme. Outros estudos in vitro são necessários, mudando os parâmetros de energia e simulando situações clínicas para propor o uso efetivo desse sistema in vivo, mas, de fato, o sistema laser em picossegundos pode melhorar a qualidade da Dentística Operatória num futuro breve. / In several already demonstrated experiments, ultrashort laser pulses on the subpicosecond range have been shown to produce a strong thermo-mechanical effect, in several different situations. Even been out side dentistry, the general aspects of subpicosecond pulses interaction with matter are of broad applications on can be used as general references. This strong thermo-mechanical effect has created objections toward the use of such lasers as a material removal too1. On the other hand, using the appropriated parameters of operation, ultra short laser pulses of subnanosecond duration could present better performance than conventional lasers operating at nanosecond regime in several aspects. Through chemical and morphological studies, they are presented the main features from interaction between pulsed laser and dental hard tissue, considering pulse width - nano or picosecond pulse. The main objective is starting to use a new system to ablate human enamel and dentin: Nd:YAG picosecond laser system. Efficient laser ablation in the picosecond regime minimizes destruction of adjacent material due to a plasma formation and etching. This avoids an excessive generation of shock waves and promotes a considerable decrease in mechanical effects. The decreasing of shock waves also reduces vibration and consequently the sensation of pain, if clinically used. Despite the small ablation rate, our results show the real possibility to use a relative simple commercial laser system for picosecond pulses to be use effectively in Dentistry. The real clinical use of a picosecond laser system could promote the Punctual and Selective Operative Dentistry, in other words, we could treat just the decayed tissue with selectivity without remove sound tissue or even promote damage to tissues around. Besides, the precise cuts maybe give us a smoother surface, which is important to prevent biofilm colonization. We need to evaluate more in vitro studies, changing parameters and simulating clinical situations to propose the effective use of this system in vivo, but in fact, we believe that the picosecond laser system can improve the quality of Operative Dentistry in a brief future.

As endotoxinas são responsáveis por importantes reações sistêmicas e locais, podendo comprometer o sucesso do tratamento endodôntico. O hidróxido de cálcio, mesmo com limitações, mostra-se como opção única efetiva entre as soluções irrigadoras e as medicações intracanal na redução das endotoxinas nos túbulos dentinários. O experimento realizado avaliou a eficiência do laser de Nd:YAG frente à uma endotoxina inoculada no canal radicular pela utilização de duas cinemáticas de irradiação. Após um período de incubação, confirmada a passagem da endotoxina inoculada no canal radicular através da dentina e do cemento radicular, a irradiação foi realizada ou com cinemática oscilatória ou com cinemática helicoidal, para posterior leitura e comparação com os grupos controle. Os parâmetros utilizados na irradiação com o laser de Nd:YAG de comprimento de onda de 1064 nm foram: 100mJ, 15 Hz, 1,5 W, diâmetro do núcleo da fibra 320 ?m, fluência do pulso 124 J/cm2, largura do pulso 120 ?s e intervalo de relaxação térmica 30 s. Os dados foram comparados pelo método ANOVA, complementado pelo teste de Tukey. As concentrações de endotoxina nos espécimes dos grupos irradiados (helicoidal e oscilatório) foram similares. Além disso, elas também foram similares às dos espécimes controle negativo e significantemente menores (p=0,0271) que as do controle positivo, que não sofreram irradiação. A irradiação com laser de Nd: YAG, nas condições deste experimento é efetiva na inativação da endotoxina da dentina radicular. / The endotoxins are responsible for important systemic and local reactions that could compromise the endodontic success. The calcium hydroxide even with limitations is the only effective option among the irrigant solutions and intracanal medications on the endotoxin reduction in the dentinal tubules. This experiment evaluated the Nd:YAG laser efficacy regarding the inoculated endotoxin in the root canal with two cinematic irradiation procedures. The irradiation was accomplished using an oscillatory and helicoidal technique after an incubation period where the passage of the inoculated endotoxin inside the root canal through dentin and cement was confirmed. Following this the analysis and comparison among the groups was performed. The Nd:YAG laser (?=1064 nm) irradiation, used parameters were: 100mJ, 15 Hz, 1,5 W, core fiber diameter of 320 ?m, pulse fluency of 124 J/cm2, pulse width of 120 ?s and relaxation time interval of 30 s. The data were statistically compared by ANOVA complemented by the Tukey\'s test (p<=0,005). The endotoxin concentration at the irradiated samples, regardless the techniques applied were similar. Moreover these concentrations were also similar to those of negative controls and significantly smaller than those of positive controls that were not irratiated (p=0,0271). The Nd:YAG laser irradiation under this experiment conditions was effective on the root canal endotoxin inactivation.

No description available.

No description available.

O objetivo desse estudo foi avaliar in vitro, a ação dos lasers de alta potência (Nd:YAG e diodo 980nm), associados ao carvão mineral como fotopotencializador, sobre a adesividade do cimento endodôntico, por meio do teste de pushout, e na interface dentina/material obturador, por meio de microscopia confocal a laser. 50 caninos foram instrumentados com sistema Mtwo até #50.04 e irrigados com hipoclorito a 1% a cada troca dos instrumentos. Os espécimes foram distribuídos em 5 grupos (n=10): GI - controle EDTAC, GII - EDTAC e laser Nd:YAG, GIII - EDTAC e laser diodo 980 nm, GIV - EDTAC, laser Nd:YAG e carvão mineral 5 g/100mL, e GV - EDTAC, laser diodo 980 nm e carvão mineral 5 g/100 mL. As aplicações de laser foram na potência de 1.5 W, frequência de 100 Hz pulsátil e fibra de 200&mu;m, por 16 segundos em movimentos elípticos (8 s no sentido coroa-ápice e 8 s no sentido ápice-coroa). Após, os espécimes foram obturados com cimento AH Plus, pela técnica de condensação lateral ativa. As raízes foram seccionadas no sentido transversal, em slices de 1mm de espessura, e submetidas ao teste de pushout em máquina universal de ensaios e o tipo de falha foi analisado em microscópio confocal a laser, e se determinou a profundidade e a uniformidade dos tags de cimento na interface dentina/material obturador. Os dados foram analisados por meio do teste ANOVA a nível de significância de 5%, seguidos dos testes de Kruskal-Wallis, Dunn e Tukey (para a comparação dos grupos). O GI apresentou a maior a resistência de união do cimento à dentina que o tratamento somente com EDTAC 17% (17,21 ± 21,75 MPa), sendo semelhante ao GII (12,21 ± 18,20 MPa) e ao GIV (14,92 ± 28,06 MPa), ambos tratados com laser Nd:YAG, com exceção do GIV, que foi adicionado de carvão mineral. O GV (8,75 ± 13,42 MPa) apresentou resultados similares aos dos grupos GII e GIV, mas a mesma similaridade foi observada quando comparado ao GIII (7,11 + 11,28 MPa), que apresentou os piores resultados. O terço apical (23,27 ± 29,21 MPa) apresentou valor de resistência de união maior que o cervical (5,92 ± 5,33 MPa) e médio (6,93 ± 7,11MPa), que foram semelhantes entre si (p>0,05). Houve predominância de falhas mistas, seguidas das coesivas. O GII (86,27&micro;m) apresentou os maiores valores de penetração de tags, com diferença estatisticamente significante em relação aos GIII (51,57&micro;m), IV (36,77&micro;m) e V (32,37&micro;m) (p<0,05). O GI (71,63&micro;m) não apresentou diferenças estatisticamente significantes em relação ao II e III (p>0,05). O GIV apresentou os menores valores, sem diferenças do III e V, (p>0,05). O terço cervical (58,44&micro;m) apresentou os melhores valores, seguidos dos terços médio (45,02&micro;m) e apical (42,24&micro;m) (p>0,05). Concluiu-se que o tratamento com laser Nd:YAG associado ou não ao carvão mineral, apresentou melhores resultados de força adesiva que o tratamento com laser diodo 980nm, exceto quando esse foi adicionado do carvão mineral. O grupo controle e o laser diodo 980nm apresentaram menores quantidades de falhas adesivas e maiores quantidades de falhas mistas comparados aos demais grupos. Ambos os lasers não interferiram de maneira negativa na penetração de cimento se comparados ao grupo controle, no que se relaciona à resistência adesiva do cimento obturador. / The aim of this study was to evaluate in vitro the influence of high-power lasers (Nd:YAG and diode 980nm) associated with mineral coal as fotopotencializer on Bond strenght of an epoxy resin-based root canal sealer to root dentin, using the push-out test, and on the dentin/filling material interface, using confocal laser microscopy. For this purposes, 50 canines were instrumented with Mtwo Rotary system up to #50.04 instrument, irrigating with sodium hypoclorite 1% at each instrument exchange. The specimens were randomly assigned to 5 groups (n=10), according the treatment of root canal dentin: group I - control EDTAC, group II - EDTAC and Nd:YAG laser, group III - EDTAC and diode laser 980 nm, group IV - EDTAC, Nd:YAG laser and mineral coal 5 g/100 mL, and group V - EDTAC, diode laser 980 nm and mineral coal 5 g/100 mL. All the lasers application was assigned according to the parameters: 1.5 W of power, 100 Hz pulsatile frequency and 200 &micro;m fiber, for 16 seconds in eliptical movements (8 s crown-down direction and 8 s apex-crown direction). Following irradiation, the canals were filled with active lateral condensation of AH Plus sealer and gutta-percha cones. After, the roots were sectioned transversally to obtain 1mm-thick slices. One of two slices from each third were subjected to a push-out test in a universal testing machine and the failure mode was analyzed with confocal laser microscopy and classified as: adhesive to the filling material, adhesive to dentin, cohesive in the filling material and mixed. The remaining slice was analyzed by confocal laser microscopy to evaluate the penetration and homogeneity of the perimeter of the root canal cross-section with sealer tags, at the dentin/filling material interface. All data were analyzed by ANOVA (at 5% significance level) following the Kruskal-Wallis, Dunn and Tukey tests (for groups comparation). Any of the proposing treatments increased more Bond strength of the sealer to root dentin that treatment with only EDTAC 17% (17.21 ± 21.75 MPa), similar to the group II (12.21 ± 18.20 MPa) and group IV (14.92 ± 28.06 MPa), both treated with Nd: YAG laser, with the exception of group IV, which was added to mineral coal. The group V (8.75 ± 13.42 MPa) had similar results to the groups II and IV, but the same similiarity were found when compared with group III (7.11 + 11.28 MPa), with lower results. Regarding the root thirds, the apical third (23.27 ± 29.21 MPa) presented a statistically higher value on Bond strenght than the cervical third (5.92 ± 5.33 MPa) and middle third (6.93 ± 7, 11 MPa) (p> 0.05). It was observed in general that there was a predominance of mixed failures, followed by cohesive failures. The lowest amount were the adhesive failures. Group II (86.27&micro;m) showed the highest tags penetration values, with a statistically difference to the group III (51.57 &micro;m), IV (36.77 &micro;m) and V (32.37 &micro;m) (p < 0.05). Group I (71.63 &micro;m) was statistically similar to groups II and III (p> 0.05). Group IV had the lowest values and was statistically similarity to groups III and V (p> 0.05). The cervical third (58.44 &micro;m) showed best values, followed by the middle third (45.02mm) and apical third (42.24 &micro;m) (p> 0.05). It was concluded that the treatment with Nd:YAG laser provides better results than the diode 980 nm laser, except when was added mineral coal. The control and diode 980 nm laser groups presented less adhesive failures and more mists failures than the other groups. Both lasers did not interfere negatively compared to the control group

[Abstract]: This thesis investigates the feasibility of closing wounds in skin tissue by laser welding as a substitute for suturing. Such a process would provide advantages in some surgical procedures. The investigation revised available theory on the action of lasers on skin tissue as a basis for the experimental program. The results of experiments using rat skin are then reported. In addition a thorough investigation of the normal (uninjured) tensile strength of rat skin was undertaken to provide a base line comparison. Laser systems permit very high-energy radiation of a single wavelength to be focused on a tiny spot, and have found application in many areas of engineering. They are also currently used in many branches of medicine including ophthalmology, gynaecology, dermatology, otolaryngology, and gastroenterology. These medical applications employ argon, YAG, and carbon dioxide type lasers. In many cases, lasers have been found to be more effective than conventional treatment methods with advantages including reduced blood loss, more accurate removal of unwanted tissue, shorter operating times and less postoperative pain and care (Gibson and Kernohan, 1993). Tissue welding using laser energy represents a small but growing area of medical research and is largely focused on anastomosis. This thesis investigates, using a specific experimental program, the feasibility of the bipolar contact Nd:YAG laser to weld cutaneous tissue. No similar published research has been identified in this area. The available literature focuses on non-contact lasers of various types and settings and mainly in the area of anastomosis. The experimental methodology and the specific technique for the bipolar contact laser is developed, tested and evaluated as part of this project. The welding techniques developed in this project overcome the previous difficulties of tissue alignment. The use of the bipolar laser probes substantially improves the ability to align the tissue edges to be joined. The probes give tactile feedback to the user and the pressure effect of the probes may assist with the welding process. The developed technique was no faster or easier than suturing. Viable welds and a useable technique for welding skin on rats were developed and tested. The resultant healing was comparable with published literature and both sutured and welded wounds returned to full strength as compared with the baseline data collected. All wounds had returned to full strength within 91 days. At 75 days there was not significant difference between laser welded and sutured wounds and they had achieved approximately 90 percent of full strength. Time to half strength was approximately 42 days and there was a larger standard deviation for both laser welded and sutured wounds. The most significant increase in strength and therefore healing occurred in the first 42 days. Simhon et al, 2001 states that a tensile strength of 0.6 N plus/minus 0.4 N was sufficient to hold tissue together. By day 7 the strength of the wound (laser welded) was more than twice the strength needed to maintain closure. There may have been sufficient healing for this to occur earlier but there were insufficient animals to allow for testing of this theory. In conclusion this experimental program and investigation has reviewed the available literature on the current use of lasers in medicine and their specific laser-tissue interaction which leads to tissue welding. It has provided a large database of tensile strength measurements collected with a reproducible methodology and reported in a standardised format. The developed technique for laser tissue welding using a bipolar contact Nd:YAG laser has been established and verified. It produces viable welds comparable in strength and healing rates to sutures.