The State of the Art of Lasers
Q&A with Robert Levine, DDS
Inside Dentistry interviews Robert Levine, DDS, Director of Laser Dentistry, Arizona School of Dentistry and Oral Health and President of Global Laser Oral Health, LLC, an ADA CERP-recognized provider for online laser training.
Inside Dentistry (ID): How has the use of lasers in dentistry evolved in recent years?
Robert Levine, DDS (RL): Early on, lasers replaced electrosurgical devices for the microsurgical removal of tissue. Dentists used them frequently for troughing, uncovering crown margins without placing cord, and performing frenectomies. Eventually, lasers were applied to periodontal therapy, which utilizes the technology in a different dynamic—a non-cutting mode. In today’s environment where dentistry increasingly utilizes digital technology, clean margins without bleeding have become more important, and lasers help to provide that.
ID: What are the most popular types of lasers, and what characteristics/applications differentiate each one?
RL: There are four main wavelengths of diode lasers that work in a single mode or that can be gated: 801 nm or 808 nm, 940 nm, 980 nm, and 1064 nm. In addition, there are two super-pulsed diode lasers (single wavelength and bi-wavelength), two types of CO2 lasers (10,600 nm for soft tissue only and 9,300 nm for hard and soft tissue), and two erbium classes of lasers (for hard and soft tissue, respectively).
For the diode lasers, their varying wavelengths will result in different levels of water absorption. These lasers have a very poor coefficient of absorption of color when they are utilized in a non-cutting mode. Cutting with a diode laser requires activating the tip. With increased wattage, more heat penetrates to the tip. That heat can be applied in different ways, including in a continuous mode, a gated mode, or a super-pulsed mode—the last of which entails working not in seconds or half-seconds, but in milliseconds. Super-pulsing allows for significant relaxation time considering the total amount of time for which the laser is being used. For example, if each pulse is 20 milliseconds, a laser in the super-pulse mode will only work for approximately 2 to 3 milliseconds, leaving a gap time of 17 to 18 milliseconds. This process, known as pulse spacing, allows the tissue to cool down significantly before the next impulse of energy is delivered by the unit.
This is very similar to the concept of the super-pulse CO2 laser; however, unlike diode lasers, CO2 lasers utilize ablation and vaporization to cut out-of-contact instead of being placed in direct contact with the tissue that requires treatment.
Several considerations are involved with the purchase of a laser, including cost, mobility within the office, and the procedures for which it will be utilized. For example, a dentist working frequently on babies might want a unit that works faster, but also offers some thermal spacing (cooling of the tissue) to minimize collateral damage to the adjacent tissues.
ID: Regarding application, in what areas does disagreement or controversy exist among dentists?
RL: The biggest controversy had been one surrounding the different diode laser wavelengths and how effective each was in terms of its ability to absorb both pigment and water. Diode lasers have a very poor absorption coefficient for pigmentation, which became evident only after extensive research. Initially, these lasers were being tested on 100% color, but because human tissue is only 10% to 15% chromophore, there is insufficient color present for the laser energy to absorb and work effectively. This was a big problem, so activation of the tip became necessary to generate enough heat for cutting in the contact mode. Now, I think we are mostly in agreement as to the physics of diode laser function. The diode lasers have a wide variety of procedural applications. In essence, they function as very controlled micro-electro-surgery units.
Controversies also persist about the wavelengths of CO2 lasers. The 10.6 CO2 laser is an excellent soft tissue laser, and the 9.3 can be utilized to cut both hard and soft tissue. In the earlier years, CO2 lasers got a bad reputation due to the excessive collateral heat generated when used in the continuous wave mode. Now, the lasers are used in super-pulsed and micro-pulsed modes, which has eliminated that issue. So the controversial opinions are mostly based on a lack of understanding of basic CO2 laser physics. Controversy also exists regarding which wavelength is best suited for treating peri-implantitis. We know that CO2 lasers offer the lowest absorption by titanium when energy is applied to the surface.
Laser-assisted periodontics is becoming a very popular application. Lasers can be used in several ways for these treatments, but no conclusive research exists demonstrating the relative effectiveness when compared with conventional periodontal therapies. When performing laser-assisted periodontics, practitioners should be aware that FDA has never approved the use of a hot tip inside the pocket. An activated tip in the periodontal pocket can generate from 400° C to 500° C; therefore, the only tips that should be used in the pocket are non-activated ones. Controlling the amount of heat is paramount, but realistically, it is very difficult to control the actual effects of energy in the pocket. The pre-sets established by each company for their particular lasers help keep dentists in the safety zone.
Additional uses for lasers include controlling bleeding and swelling. Based on the energy being used, dentists can also use them to achieve some biostimulation. They can also be used to seal off nerve endings and lymphatics, so as a supportive technology, they offer many benefits.
With respect to the use of lasers in the treatment of peri-implantitis, more research needed to determine the most effective type and wavelength.
ID: What types of developments are next on the horizon?
RL: One of the most exciting new developments is a timing device, which I expect to see on one of the new lasers coming to the market by the end of the year. When dentists are performing laser-assisted periodontal procedures, they can set the laser for the amount of time that they want to stay in the pocket. When they press on the pedal, the laser will only operate for that set amount of time.
Lasers designed to effectively remove bonded orthodontic brackets without cutting tooth structure as well as ones for performing pulpal vaporization are in development at the present time. These will require the use of new wavelengths.
Low-level laser technology is also coming to the forefront, but has yet to gain much traction in dentistry. This technology is utilized in bi-wavelength lasers that feature two waves working synergistically. For example, one wave can be reducing inflammation while the other wave is providing immediate pain relief. In the future, this technology could allow us to achieve better results when working on patients who are undergoing chemotherapy and consequently have mucositis in their mouths. The key is getting a sufficient level of oxygen to the tissue to effectively support healing. Red light has been shown to do this effectively, so low-level lasers will probably be a leader for this application.
Beyond these advancements, a variety of new wavelengths for different applications are in development as well. And I anticipate that any new lasers brought to market will be more compact and cost-effective, which should lead to increased utilization in the dental office.
About the Author
Robert Levine, DDS
Director of Laser Dentistry
Arizona School of Dentistry and
Global Laser Oral Health, LLC