Laser surgery in the larynx. Early clinical experience with continuous CO 2 laser.

The aims of this paper are to briefly describe laser physics, the types of lasers currently available for use on soft tissues focusing primarily on CO2 and Nd:YAG laser energies, the histological effects of lasers on oral tissues, laser safety, the clinical applications of lasers on oral soft tissues, and future directions. Of the two types of lasers currently available for dental applications, both the CO2 and Nd:YAG lasers can be used for frenectomies, ablation of lesions, incisional and excisional biopsies, gingivectomies, gingivoplasties, soft tissue tuberosity reductions, operculum removal, coagulation of graft donor sites, and certain crown lengthening procedures. The advantages of lasers include a relatively bloodless surgical and post-surgical course, minimal swelling and scarring, coagulation, vaporization, and cutting, minimal or no suturing, reduction in surgical time, and, in a majority of cases, much less or no post-surgical pain. CO2 lasers, compared to Nd:YAG are faster for most procedures, with less depth of tissue penetration and a well-documented history. There have been recent reports on the use of the Nd:YAG laser for periodontal scaling, gingival curettage, and root desensitization, but further research needs to be conducted. Both the CO2 and the Nd:YAG laser have limited use in conventional flap therapy.

Current Status of Lasers in Soft Tissue Dental Surgery

The possibility of revascularizing the myocardium with high-energy laser was investigated based on the finding that the laser beam could produce small channels in the tissue of the myocardium that were devoid of debris and scarring. The technique was investigated in 4 groups of 6 mongrel dogs each. In 3 of the groups, the left anterior descending (LAD) coronary artery was ligated above the first diagonal branch and the myocardium was treated with the laser energy according to the protocol of that group. In the fourth control group, the LAD artery was ligated but the myocardium was not subjected to laser treatment. In the first 3 groups, the myocardium was protected by the channels produced by the application of the laser energy. The animals were subsequently sacrificed at various intervals. In the control group, all of the animals died within 20 minutes of ligation of the artery. At autopsy, the epicardial sites of the channels created by the laser were clearly visible and a lack of charring in the channels was demonstrated. The penetration through the endocardial surface could be demonstrated. Microscopically, the channels were patent and endothelialized. It is concluded that the channels created in the myocardium effectively helped to protect the myocardium from acute coronary artery occlusion in this model in dogs.

Revascularization of the heart by laser

We describe the history, guiding mechanism, recent advances, applications, and future prospects for hollow-core negative curvature fibers. We first review one-dimensional slab waveguides, two-dimensional annular core fibers, and negative curvature tube lattice fibers to illustrate the inhibited coupling guiding mechanism. Antiresonance in the glass at the core boundary and a wavenumber mismatch between the core and cladding modes inhibit coupling between the modes and have led to remarkably low loss in negative curvature fibers. We also summarize recent advances in negative curvature fibers that improve the performance of the fibers, including negative curvature that increases confinement, gaps between tubes that increase confinement and bandwidth, additional tubes that decrease mode coupling, tube structures that suppress higher-order modes, nested tubes that increase guidance, and tube parameters that decrease bend loss. Recent applications of negative curvature fibers are also presented, including mid-infrared fiber lasers, micromachining, and surgical procedures. At the end, we discuss the future prospects for negative curvature fibers.

Negative curvature fibers

The management of laryngeal and tracheal stenosis continues to challenge us, despite advances in surgical techniques and better understanding of the wound healing process. Injury to the airway mucosa is the inciting event, regardless of the cause of the stenosis. Mitomycin-C is an antineoplastic antibiotic that acts as an alkylating agent by inhibiting DNA and protein synthesis. It can inhibit cell division, protein synthesis, and fibroblast proliferation. Topical application of mitomycin-C (0.4 mg/mL) was used as an adjuvant treatment in the endoscopic laser management of laryngeal and tracheal stenosis in 15 patients. Fourteen patients (93%) have shown improvement of their airway and resolution of their preoperative symptoms. After a mean follow-up of 18 months, no complication was noted with regard to the application of mitomycin-C. This study gives promising findings on the efficacy and safety of mitomycin-C as an adjuvant treatment in the management of selected cases of laryngeal and tracheal stenosis.

Mitomycin: effects on laryngeal and tracheal stenosis, benefits, and complications.

The characteristics of CO2 lasers that render them interesting for surgical applications are reviewed. An instrument consisting of an integrated CO2 laser and beam manipulator, designed specifically for surgical research work, is descirbed. Operational characteristics of the instrument relevant to such work are reported. An accessory for endoscopic surgery is described and instrumentation for microsurgery is discussed. Surgical researches now in progress with this instrument are mentioned.

Davis Tw

Papers

A CO2 laser for surgical research.