By Noel Berger, DVM, MS; Martin Kaplan, DMD; and Peter Vitruk, PhD For The Education Center
Originally Published In Veterinary Practice News, September 2018 –Download as a PDF
Surgical lasers have been widely used in both human and veterinary medicine for nearly three decades. The physics of light absorption by the soft tissue’s four main chromophores—water, melanin, hemoglobin, and oxyhemoglobin— helps to explain the science and safety of the surgical lasers. For instance, for water, the strongly absorbed wavelength of CO2 surgical lasers (circa 10,000 nm) allows for efficient photothermal vaporization and coagulation of the soft tissue at the same time, which simplifies many soft tissue surgeries and makes them more enjoyable for practitioners. The weaker-absorbed wavelengths of laser diodes (circa 1,000 nm) make them highly inefficient cutters but excellent coagulators (diode’s hot fiber tips can cut soft tissue thermomechanically, similar to electrocautery). These and other aspects of laser-tissue interaction (e.g. the depths of cut and coagulation) are at the heart of surgical laser education and training through American Laser Study Club (ALSC).
Human laser dentistry
The CO2 laser is widely used in a variety of areas of human soft tissue dentistry for a wide array of indications, including gingivectomy/gingivoplasty; removal of epulis, fibromas, and mucoceles; raising mucoperiosteal flaps; operculectomy; exposure of impacted teeth; treatment of aphthous ulcers; and others. The laser is especially beneficial in highly vascularized areas or zones where precise cutting is important for aesthetics (for instance, during gingival recontouring).
In the hands of an experienced clinician, the appropriate CO2 laser settings (such as spot size, power, and pulsing characteristics) and hand speed can result in small, less than 100-micron-thick zones of thermal tissue change. Patients reported less postoperative pain and discomfort with laser surgery than with scalpel surgery. Healing following CO2 laser surgery is enhanced and less painful than with cryosurgery or electrosurgery. Moreover, studies have demonstrated that compared to conventional scalpel surgery, CO2 laser surgery is associated with a diminished risk of scarring and wound contraction.
The case sequences in Figures 1 and 2 demonstrate the ability of a flexible fiber CO2 laser to efficiently incise oral soft tissue while simultaneously coagulating it. Thus in Figure 1, a flexible fiber CO2 laser (LightScalpel, Bothell, Wash.) was used to release the lingual frenum in a 68-year-old patient (Figure 1a). The laser enabled the clinician to ablate the frenal tissue and spare the underlying blood vessel (Figure 1b). Figure 2 shows laser gingivectomy and gingival recontouring in a 9-year-old patient. In this case, the LightScalpel CO2 laser allowed the clinician to precisely remove hyperplastic gingival tissue while sparing the underlying hard tissue and effectively managing hemorrhage (Figure 2b). Healing progressed without complications, and Figure 2c shows the surgical site with excellent cosmesis.
Veterinary laser dentistry
The mouths of dogs and cats have a rich blood supply and are extremely well innervated. The epithelial lining of the oral cavity is composed mostly of water, making the tissue an ideal target for CO2 laser surgery. The coefficient of absorption of CO2 laser light by water is very high, meaning the energy is efficiently absorbed by water in oral tissues. Veterinary laser surgeons can use these properties to create precise incisions and ablations with minimal collateral damage to adjacent tissues, thus preserving the integrity of vital structures. Veterinary dentistry performed with sharpened metallic instruments causes a significant amount of bleeding and pain; however, when procedures are performed with a CO2 laser there is less postoperative pain and there is coagulation of capillaries that provide hemostasis and enhanced surgical visualization.
A common indication for the use of CO2 laser energy in tooth extraction is the creation of a mucoperiosteal flap. Some prefer to use the SuperPulse mode for this procedure to minimize any heat conduction to surrounding tissue. When a beam diameter of 0.25 mm is used, 2-3 W is all that is required to produce a full-thickness incision through the oral epithelium and underlying connective tissue without affecting the jaw bone (Figures 3a-c). The efficient absorption of CO2 laser energy by the water in oral tissues prevents undesired damage beyond 0.1 mm from the edge of the incision. Care must be taken not to irreversibly target a tooth, or to use excessive power, which will create too deep of an incision and thus burn the underlying bone. As power and incisional depth are directly related, using an appropriate power setting for the patient’s size will prevent damage. The benefits of using a CO2 laser for mucoperiosteal flap creation are the enhanced surgical visualization and postoperative pain reduction compared to using a scalpel.
Other oral surgical procedures actually are improved by the use of CO2 laser energy, especially when considering brachycephalic breeds (dog or cat). Elongated soft palate resection is a commonly performed procedure that helps these patients to have a larger diameter airway. Patient selection is important to avoid overcorrecting redundant uvular tissue. A long and thick soft palate can be trimmed back if it extends over the epiglottis beyond the level of the caudal pole of the tonsils (Figure 4). Tonsillectomy is sometimes performed simultaneously in severely affected patients. Using continuous wave exposure, unnecessary tissue is removed under tension. Some thermal necrosis is required to coagulate capillaries of the soft palate during the excision. Excessive heat should be avoided to prevent damage to the palatine artery exiting the hard palate into the soft palate. Because power density and beam diameter are inversely related, using a larger diameter beam may require using higher power settings to perform the procedure rapidly.
Another preferred use of CO2 laser energy in the mouth of cats is to manage oropharyngeal inflammation. This is a complex disease that is debilitating to its victims. Multiple therapeutic combinations are required to achieve success, including thorough and accurate diagnosis, full mouth dental extractions, antibiotic therapy, anti-inflammatory medication, nutritional management, and CO2 laser treatment of the affected gingiva. Once the foul oral tissue has been debulked, the CO2 laser can be used to ablate away the remaining tissue. This means to target the diseased tissue at low power and evacuate the carbonized tissue in the resultant smoke plume. The goal is to remove the epithelial tissue and allow firmer, organized, connective tissue to grow in its place.
The CO2 laser wavelength, SuperPulse settings, and a variety of focal spot sizes and shapes enable the clinician to perform a char-free, bloodless surgery with well-controlled speed and depth of vaporization, with a dynamic range from micrometers to millimeters. The CO2 laser surgery learning curve is fairly short, and the laser settings are easy to adjust. The authors strongly suggest that in order to use the surgical laser safely and confidently, the clinician should seriously consider pursuing education, training, and certification, e.g. through the ALSC.
Martin Kaplan, DMD, is a part-time adjunct clinical instructor in the pediatric postgraduate department at Tufts University School of Dental medicine in Boston. He has been an early adopter of laser dentistry and has been standard certified by the Academy of Laser dentistry since 2004. He recently earned his Fellowship status at the Academy of Laser Dentistry. He has lectured nationally and internationally, has co-authored several articles, and has been a contributing author of the unique, first of its kind, Color Atlas of Infant Tongue-Tie and Lip-Tie Laser Frenectomy. Dr. Kaplan is the developer of the first in the country comprehensive Infant Laser Frenotomy class at Tufts University Dental/Medical Center in Boston. He is a Diplomate of the American Board of Laser Surgery (ABLS) and the director of Dental Laser Education and Development for ABLS.
Noel Berger, DVM, graduated in 1988 from the New York State College of Veterinary Medicine, and also earned the MS degree in veterinary clinical sciences in 1989 from Cornell University. Following a residency in pathology, he entered private small animal veterinary practice; since that time he has been a clinician and successful business owner. He was certified by the American Board of Laser Surgery in veterinary surgery, physics, and safety in 2000 and provided leadership in the practical use of surgical and therapeutic lasers. He was a charter member of the Veterinary Surgical Laser Society and served as its president in 2002. He is the first author of several peer-reviewed papers in veterinary laser surgery, laboratory diagnostics, and regenerative medicine. He has co-authored several book chapters and published a textbook of small animal laser surgery. He is an internationally recognized speaker, having instructed hundreds of veterinarians and technicians on how to use therapeutic and surgical lasers. Dr. Berger delights in teaching the theory and safe techniques required to minimize post-surgical pain and inflammation using lasers.
Peter Vitruk, PhD, is a founder of AescuLight-LightScalpel LLC in Bothell, Wash. He is a member of The Institute of Physics and the founder of American Laser Study Club. Dr. Vitruk can be reached at 866-589-2722 or [email protected]
This Education Center article was underwritten by Aesculight of Bothell, Wash., the manufacturer of the only American-made CO2 laser.