Robert Levine, DDS; Alan Dalessandro, DDS; David Garber, DMD; and Robert Lowe, DDS, FAGD, FICD, FADI, FACD, FIADE, FASDA
Q: In which applications of dentistry can we expect to see an expansion in the use of lasers?
A: Dr. Levine
As Director of Laser Dentistry at the Arizona School of Dentistry and Oral Health, I am constantly asked by my students about the future of lasers in dentistry. I usually respond by saying that “the sky’s the limit.” The technology first came to the forefront in 1960, when Theodore Maiman was able to produce laser light from a red ruby crystal. It took almost 30 years to get approval for the first dedicated laser for dental use, which was the Nd:YAG laser in 1989 by Meyers and Meyers. Now, 26 years later, there are both hard and soft-tissue lasers available to the dentist in a variety of wavelengths. Lasers have always had the ability to cut tissues (ablate, vaporize, incise, excise, etc.); however, I feel that our next frontier will be in the arena of therapeutic lasers. To define a therapeutic laser, I think it is only fair to compare it to our traditional photothermal lasers. For a laser to be considered therapeutic, it cannot generate enough heat to break down tissue; therefore, photothermal lasers are not therapeutic. Therapeutic lasers, as defined, are meant to heal.
Low-level laser therapies (LLLT) have been used to treat inflammation, edema, and to repair superficial lesions. The latest models work in modes that are synergistic in nature. Our LEDs, which are monochromatic but not as coherent as are the photothermal laser, are the low-power density models that act fast on inflammation. In low IR range, there are high-power density (HPD) lasers, which have an immediate effect on pain. The HPD laser is in a range where it does not break down tissue, and energy transfer must not be thermal. When used properly, each mode will reciprocally reinforce the other.
It is also important to understand the physiology of the laser process. Pathology in a cell occurs when the balance of adenosine triphosphate (ATP) formation and various metabolic processes lead to pathology in a cell. The cell then passes from an optimal energy state to utilizing its energy to fight off pathology. As a result, the cell becomes stressed, needs to get oxygen back into the metabolic process, and therefore returns to a normal balance.
Tissue inflammation occurs when “ischemic tissue” or “stressed tissue” produces mitochondrial nitric oxide (MTNO). Cytochrome c oxidase (CCO) is a major absorber of red light and near-IR invisible range light. The light absorbed by CCO photo-disassociates the MTNO bond and allows O2 back into the metabolic system. Thus, we can see an increase in ATP formation and return to cellular balance.
One last aside would be to see the effects a super-pulsed O2 laser would have on peri-implantitis and laser-supported periodontal therapy. Diode lasers and Nd:YAG lasers are already two big players in this treatment area.
Speaking from a periodontist’s viewpoint, periodontal therapy has always been very evidence-based. So, this had caused the periodontist to overlook the benefits of lasers until recently, as several studies have shown the efficacy of Nd:YAG and Er:YAG lasers in treating periodontitis and peri-implantitis. Several studies show that a combination of both can be very beneficial for enhancing results in traditional and flapless periodontal therapy. The Nd:YAG laser has the benefit of killing black-pigmented bacteria, separating connective tissue from epithelium in the periodontal pocket, and creating a fibrin clot that can contain a host of growth factors. The Er:YAG laser, with the chromophores being more water and hydroxyapatite, can work on root surfaces to clean, detoxify, and actually remove calculus and break apart the walls of bacteria; on implant surfaces, it can also remove calculus, detoxify, and make the surfaces biologically acceptable once again. So, with the advent of both wavelengths, periodontal therapy has been pushed to a new level.
Er:YAG lasers are also used to help de-epithelialize flaps and papillas in gingival grafting, while Nd:YAG lasers can create fibrin clots to enhance bone and soft-tissue healing. Er:YAG lasers have been used in extraction sockets to decorticate and detoxify, and are also very helpful in removing granulation tissue. They can also be used in implant osteotomies to decorticate, detoxify, and stimulate blood flow so that the implant has a good base for healing. The Nd:YAG laser has been used for photobiomodulation, which is otherwise known as low-level laser therapy, in treating postoperative discomfort or myofascial pain and discomfort. Numerous studies have shown how effective it is to reduce oxidative tissue stress in the cells, stimulate ATP, increase blood supply to the area, and help the lymph nodes to become more efficient. This will become bigger and bigger as people realize its benefits. The Er:YAG laser, on the other hand, has been used non-ablatively on the tonsillar pillars, soft palate, and uvula to cause shrinkage of the collagen, thus stopping or reducing snoring. This procedure is called NightLase® therapy (Fotona, www.fotona.com); it is very effective and now very much in demand.
When I teach laser sciences, I always teach the doctors that they need to be brilliant on basic biology, the procedures they intend to perform, and the physics of lasers and their potential. They could then use a laser as a tool to create a better result than ever before. When this is done, the types of uses are limitless, and the results improve dramatically. So, in the future, my suggestion is to have an open mind, sit back, and watch the body take over with healing from the benefits of laser therapy.
Recent FDA approval of 9.3-µ CO2 lasers for use in dentistry, along with beam manipulation technologies commonly used in other industries ranging from tattoo removal to marking plastic bottles, will drive more applications and accelerated adoption of lasers in dentistry.
The original research with 9.3-µ CO2 lasers conducted at UCSF over 30 years ago was focused on preventing cavities rather than treating them. Now that the FDA has approved the wavelength for cavity treatment, it is only a matter of time until we see the same wavelength used to facilitate long-term cavity prevention.
Because the 9.3-µ laser is so highly absorbed in hydroxyapatite, it can also ablate tooth structure at speeds nearing that of the drill when delivered at higher power levels. Because slow cutting was a major barrier to adoption of previous hard tissue laser technologies, one can expect to see adoption increase dramatically now that that problem is solved. The combination of speed and anesthesia-free treatments saves a lot of time, facilitates multi-quadrant dentistry, and sends the patients home smiling. I have to imagine that as more dentists experience this, adoption will increase dramatically.
CO2 has long been seen as the gold standard for soft-tissue cutting, but it was hard to rationalize the expense with low-cost diodes and other alternatives. Now that CO2 can be used on both hard and soft tissue without switching tools, it makes economical sense to have it in the operatory. It is wonderful to simply push a button and switch from bloodless soft-tissue ablation to high-speed enamel ablation without having to administer anesthesia.
Lasers have been utilized in dentistry for almost two decades, and in medicine and ophthalmology even longer. The minimally invasive nature of lasers, along with improved tissue response and healing, has made them a very attractive technology for dental procedures accomplished in the microenvironment of the oral cavity.
So, where in dentistry can we expect to see an expansion in the use of lasers in the near future? Personally, I have used lasers in my practice since the early 2000s. I cannot imagine practicing restorative dentistry without them. For contouring soft tissue with little to no necrosis, soft-tissue crown lengthening for restorative access, and minor hard-tissue re-contouring for biologic width violation (Erbium wavelengths only), lasers make the work easier and the outcomes better than many of the “conventional” therapies. Accessibility and affordability of laser technology will continue to drive adoption with dentists, providing wider access to laser care for patients; if you follow almost all other technology trends, especially in dentistry, things come down in price and settle in at a price point that equates the device’s value, eg, intraoral cameras, digital x-ray sensors, etc. In the case of lasers, diodes have already realized this trend, with a drop in price over the last 5 to 10 years that has driven the adoption rate as high as 50% of all dentists. All-tissue lasers remain a niche product, but one can expect some laser manufacturer to break through with an economical, practical version, which will drive widespread adoption, as it did with diodes, especially as general dentists continue to understand the excellent outcomes all-tissue lasers offer.
Also, as research with lasers continues, there will be more step-by-step protocols for specialists and general dentists to simplify the delivery of laser care to patients. One emerging trend is that of peri-implantitis treatment and the rescue of failing implants. Inflammatory tissue can be safely removed from the implant surface with an Erbium wavelength laser allowing the dentist to bone graft and potentially recover from implant failures.
Also, one of the most appealing applications of an all-tissue dental laser is the notion of performing cavity preparations without using a high-speed drill and local anesthesia. Despite claims from various manufacturers through the years, it is still a fact that performing a cavity preparation without a handpiece and local is not universal or predictable enough to incite widespread adoption, yet. In general, laser technology that is designed to ablate enamel, dentin and bone has seen numerous advances since the notion of cutting a cavity preparation with a laser was first investigated in the late 1980s and early 1990s, but this application needs further innovation, which, according to many laser companies, remains a major focus in their research and development efforts. I would expect scientific and technological innovation that will move cavity preparations toward no-shot, no-drill reality.
About the Authors
Robert Levine, DDS
Director of Laser Dentistry
Arizona School of Dentistry and Oral Health
Alan Dalessandro, DDS
Hoffman Estates, Illinois
David Garber, DMD
Clinical Professor in the Department of Periodontics
Medical College of Georgia School of Dentistry
Clinical Professor in the Department of Oral Rehabilitation
Medical College of Georgia School of Dentistry
Robert Lowe, DDS, FAGD, FICD, FADI, FACD, FIADE, FASDA
Charlotte, North Carolina