This section is intended to provide dental professionals with a comprehensive overview of laser dentistry, with a focus on periodontal and surgical treatment.
Lasers: An Introduction
The NYLI recommends that dentists read the following informative articles featured on the website of the Academy of Laser Dentistry:
Types of Lasers Used in Dentistry
Ophthalmologists began using the ruby laser, developed by Maiman, in the early 1960’s. Today, numerous lasers are available for medical and dental use, including the CO2, Nd:YAG, Er:YAG, Er,Cr:YSGG, Diode and others.
Initially, the CO2 and Nd:YAG were the most commonly used lasers for surgical dental procedures. Since the beams for both are infrared and invisible, the manufacturers often add a quartz fiber with a red laser to provide the user with a visible aiming beam.
The laser energy from the Nd:YAG is transmitted through fiber-optics into a handpiece, while the laser energy from the CO2 is transmitted through a series of mirrors in an articulating arm and focusing lenses into a handpiece. Hollow wave guide technology through a flexible tube is also available to increase versatility.
Substantial data exists supporting the use of both the CO2 and Nd:YAG laser for soft tissue surgery. The CO2 laser received FDA clearance in 1976.
Carbon Dioxide (CO2) Laser
The CO2 laser causes a rapid rise in cellular temperature, leading to cellular rupture and the release of vapor and debris. Debris at the site of laser impact is carbonized tissue, called the char. During pulsed or gated modes, char formation is slower than during the continuous wave mode. Proper use of the laser requires continuous removal of the char during surgery.
Water readily absorbs the CO2 laser wavelength. In soft tissue, almost all of the energy is converted to heat and absorbed at the surface. The scattering or penetration of heat is minimal. The zone of coagulation necrosis is narrow. This laser operates without contacting the tissue. When the laser is defocused, blood vessels up to a 0.5mm diameter are sealed. This hemostasis provides a dry field for improved visibility.
Higher energy levels vaporize and remove tissue, while lower energy is used for hemostasis and coagulation.
Neodymium:YAG (Nd:YAG) Laser
Nd:YAG laser energy is scattered in soft tissue, as opposed to the CO2 Laser, where the laser energy is absorbed at the surface. The Nd:YAG wavelength seeks pigments, therefore inflamed tissue with a high hemoglobin count favors absorption. This thermal effect is ideal for ablation of hemorrhagic tissue and for hemostasis of small vessels. The scattering effect makes it difficult to control the depth of laser penetration. The depth of thermal tissue damage can be as high as 3mm in soft tissue.
The Nd:YAG Laser utilizes flexible optical fibers and are commonly used in endoscopy and arthroscopic surgery. Newer sapphire and ceramic tips for contact use have been developed that allow for greater precision at lower wattage settings. Contact tips provide surgeons with tactile feedback. FDA clearance for use of the Nd:YAG Laser on oral soft tissues was granted in 1990.
Erbium:YAG (Er:YAG) Laser
In 1997, the FDA granted safety clearance for the use of Er:YAG lasers on oral hard tissues. The Er:YAG wavelength is ideal for absorption by hydroxyapatite and water, making it efficient at enamel, dentin and bone ablation. Water evaporates into steam in irradiated tissues, resulting in micro-explosions of hard tissues. Very little heat is generated in the surrounding tissues. Er:YAG laser energy is absorbed by water 15,000 times more than that absorbed by the Nd:YAG. Tissue ablation by Er:YAG is not caused by heat.
A fiber-optic system delivers Er:YAG laser energy to a handpiece, along with a water spray, which is necessary to achieve maximum cutting efficiency.
In 1998, the YSGG laser obtained FDA clearance for use on all oral tissues. It uses a patented combination of laser energy, water and air to safely and effectively ablate enamel and dentin. The wavelengths of the YSGG and the Er:YAG are very similar. When the water spray is minimized, the laser effectively cuts and coagulates soft tissues. By 2000, the FDA expanded its clearances to include soft tissue indications.
A series of additional FDA clearances followed: endodontics (2002), cutting oral osseous tissues (2003) and periodontal therapy, including laser “curettage” and hard-tissue crown lenthening (2004).
Diode lasers received FDA safety clearance around 1996. They also transmit laser energy through flexible fiber-optics in a handpiece. Diode energy is absorbed by pigmentation in the soft tissues. When in contact mode, the diode laser can be used for soft tissue removal and hemostasis. The diode laser has similar applications as the Nd:YAG laser, with less thermal effects.
Cold Lasers – Low Level Laser Therapy (LLLT) / Biostimulation
Diode laser energy, as well as residual energy from the other dental lasers, is thought to penetrate deeper into tissues with no heating effect or damage. The energy is directed deep into the targeted area, stimulating the body’s cells, which in turn, convert the energy into chemical energy to promote natural healing.
Cold lasers are often compared to “acupuncture with a laser beam.” In most LLLT treatments, the laser beam is used to stimulate the body’s acupoints or damaged area in an attempt to increase the blood supply and mitochondrial activity. One manufacturer has developed the OsseoPulse for enhancing bone regeneration and implant healing. Further studies are necessary to validate these claims.
Laser studies focusing on use in periodontal treatment began to appear in the mid-1990’s. Earlier studies looked at CO2 and Nd:YAG lasers for soft tissue procedures, with evidence of less bleeding and less pain than with a scalpel. Some studies also suggested that laser wounds heal more quickly and produce less scars. Early reports also suggested that low-level laser irradiation improved wound healing.
In the past decade, numerous studies seem to clearly substantiate many of these earlier claims.
Periodontal and Hard Tissue Applications
An important aspect of periodontal treatment is the effect of laser energy in root debridement. Nd:YAG laser application to root surfaces seems to result in protein and mineral alterations, a reduction in fibroblast attachment, and alteration of the smear layer following scaling and root planing. Neither the diode nor the Nd:YAG laser showed efficacy in removing calculus.
The Erbium lasers demonstrate the best results when used directly on hard tissues, creating a biocompatible surface for soft tissue attachment. These lasers have the ability to remove bacterial toxins, calculus and diseased cementum from the root surface. Unlike with the Nd:YAG and CO2 lasers, melting, charring and carbonization does not occur. Root conditioning and removal of the smear layer from hand instrumentation also seem to be effective.
The YSGG Waterlase has received FDA clearance for laser cutting, contouring and resection of intraoral bone. Few published reports on periodontal use exist, though, it is reasonable to extrapolate YSGG benefits from Er:YAG studies because their wavelengths and tissue absorption properties are very similar.
Soft Tissue Applications
Lasers benefit almost all soft tissue ablative procedures, including techniques related to implant therapy and mucogingival surgery. The CO2 and Erbium lasers can enhance periodontal and regenerative therapy through de-epithelialization, a technique for epithelial exclusion.
The diode and Nd:YAG lasers have been recommended for subgingival curettage and “new attachment” procedures. The LANAP procedure is a proprietary protocol that is performed with the Periolase Nd:YAG Laser. Based on one human clinical study, the laser manufacturer claims superior results. Though minimal evidence exists to support the claim that these procedures are superior to conventional treatment and some studies demonstrate the presence of root surface damage.
Recently, the YSGG laser has received FDA approval for it’s own protocol, called Deep Pocket Therapy with New Attachment. New side-firing laser tips deliver laser energy in all directions. Long term human studies have been completed and are awaiting publication. Given the YSGG’s positive safety profile on root surfaces and periodontal tissue, the results are potentially very promising.