Dental Lasers
Nearly every dental specialty—periodontics, endodontics, orthodontics, and oral andmaxillofacial surgery— can use laser technology to fulfill their respective treatment objectives.
As the digital age moves forward, dentistry follows suit, gradually incorporating state-of-the-art technologies like dental lasers into practice to enhance the prevision and predictability of patient care. Whether to embrace a holistic approach to minimally invasive procedures, or to remain ahead of the curve, dentists incorporating lasers into appropriate treatments understand the benefits of their use, as well as the technology’s limitations.
Over the past 52 years since their introduction, lasers have been developed for use in manufacturing, electronics, consumer, and medical industries.1 Today, several types of lasers are used in dentistry, and their applications range from soft-tissue procedures, hard-tissue (ie, tooth) procedures, diagnostics, intraoral scanning for digital impressions, low-level laser therapy to relieve pain, and tooth whitening.2,3
The FDA marketing clearance for dental lasers is known as a 510(k) and is both device and application specific, explains Don Coluzzi, DDS, clinical professor in the Department of Preventive and Restorative Dental Sciences at the University of California, San Francisco School of Dentistry. A broad clearance for soft-tissue surgery includes incision, excision, and coagulation of intraoral soft tissues. Additional procedures include treating herpetic lesions/aphthous ulcers; sulcular debridement and cementum-mediated new attachment (both specific to periodontics); reducing bacterial level and inflammation; and pulpotomy.
Hard-tissue applications include composite curing; tooth whitening; carious lesion removal and tooth preparation; osseous surgery such as osteotomy and shaping of bone and osseous crown lengthening; and endodontic procedures such as canal debridement, preparation, cleaning, and apicoectomy.
Still, other laser applications in dentistry include photobiomodulation procedures. These include temporary increase in local blood circulation, temporary relief of minor muscle and joint aches, pains, and stiffness, and relaxation of muscles; for muscle spasms, minor pain, and stiffness associated with arthritis; and topical heating for elevating tissue temperature for temporary relief of minor muscle and joint pain. Additionally, there are diagnostic applications, such as detecting carious lesions and calculus, Coluzzi explains.
Dental laser technology is based on specific wavelengths that determine the tissues (eg, hard or soft) on which a particular device can be used.2 Nearly every dental specialty, including periodontics, endodontics, orthodontics, and oral and maxillofacial surgery—among other areas, have dental lasers of different wavelengths available for use to facilitate appropriate procedures.4 Therefore, before purchasing or using a laser in practice, dentists should understand a laser’s mechanism of action, tissue effects, and laser safety, as well as determine the procedures to which they would like to apply laser techniques.5,6 No single wavelength will treat all dental tissues completely.7
"If you understand your treatment objectives and what you’re trying to accomplish, then selecting the appropriate laser to do that becomes very important,” explains Scott Benjamin, DDS, a private practitioner, lecturer, and author from Sidney, New York and associate professor and director of Advanced Technologies and Informatics at Roseman University of Health Sciences, College of Dental Medicine. "A laser very good at one procedure may not be be very good at another.”
According to Steven R. Pohlhaus, DDS, the dental lasers in common use today include erbium, Nd:YAG, diode, and CO2, with each having different biologic effects and procedures associated with them based on their laser wavelengths. The Er:YAG lasers have wavelengths of 2940 nm, and Er,CR:YSGG have wavelengths of 2,780 nm. These lasers are suitable for both hard- and soft-tissue procedures and can be used anywhere a scalpel would be, such as periodontal procedures, gingival contouring, biopsies, frenectomies, or pre-prosthetic procedures.
Nd:YAG lasers are primarily used for periodontal treatments. With wavelengths in the near infrared range of 1,064 nm, this laser’s energy is absorbed by pigment in the soft tissue, primarily hemoglobin and melanin, Pohlhaus explains. Applications include debridement and disinfection, gingivectomy, frenectomy, impression troughing, and biopsy.
Diode lasers, which produce invisible near infrared wavelengths ranging from 805 nm to 1,064 nm, are for soft tissues only. One exception is caries detection lasers (eg, DIAGNOdent, KaVo Dental, www.kavousa.com), which has a visible red wavelength of 655 nm. Pohlhaus says that like other soft-tissue lasers, diode lasers are effective for gingivectomies, biopsies, impression troughing, and frenectomies; they also demonstrate bactericidal effects and can be used for adjunctive periodontal procedures, laser-assisted tooth whitening, and photobiomodulation.
Producing wavelengths of 10,600 nm, CO2 lasers have been used in dentistry for more than 25 years and are excellent for incising and excising biopsies, frenectomies, gingivectomies, and other procedures, Pohlhaus notes.
In addition to wavelength, other attributes of dental lasers also affect the applications for which they would be appropriate, explains Benjamin. These include whether or not a laser operates in continuous wave mode (ie, the laser is on the entire time that the unit is powered on) or pulsed mode (ie, the energy is released in bursts); peak power; and ability to control the laser settings—both power and pulse.
"As light energy goes into tissue, if it’s absorbed very readily on the surface, that’s going to vaporize it by raising the temperature until the water in the cells turns to steam, explode, and the tissue is removed,” Benjamin elaborates. "If you want to use a laser for healing, you want to use a wavelength that is not readily absorbed, but is able to penetrate deeper down into the tissue and stimulate a biological response for healing.”
Ashley Goodman, DDS, a private practitioner and lecturer from San Diego, California, offers a good example of why some laser advocates use more than one laser in their practice to accommodate different needs. "For an extraction surgery I recently performed, I used an Erbium laser, after which I went back in with a diode to provide laser therapy to accelerate healing and increase the patient’s comfort,” Goodman explains.
Soft-Tissue Dental Lasers
Within surgical procedures, good hemostasis and a reduced need for sutures is achieved when soft-tissue lasers are used.1,6 Other benefits include selective and exact interaction with tissues, ability to lessen the bacterial load in the surgical field, effectual reduction in inflammation, and stimulating new production of fibroblasts and osteoblasts for improved healing.6 Additionally, lasers have been instrumental for managing gingival tissues for esthetic treatment, non-surgical and surgical periodontal pocket therapy, osseous surgery, and implant therapy.8,9
Comparing a laser to a scalpel, Coluzzi says the laser offers good to excellent coagulation, tremendous reduction of pathogens, temporary sealing of the nerve endings and lymphatic vessels, and possibly less need for sutures. Additionally, there is usually less scar formation.
The characteristics of soft-tissue dental lasers have been beneficial in helping to manage periodontal disease.8 Advocates of lasers in dentistry point to advantages that lasers provide that aren’t possible with other operative techniques.5 Various wavelengths used for treating chronic periodontitis in addition to conventional scaling and root planing have been cited by some as effectively reducing probing depth and subgingival bacterial populations.10
However, other research has shown the need for developing and implementing an evidence-based approach to using lasers for treating chronic periodontitis, common oral soft-tissue problems, root-surface detoxification, and treating chronic periodontitis. While there is evidence to support that lasers are more beneficial than traditional modalities of therapy, there is still insufficient proof as to which specific wavelength is responsible.10
According to Benjamin, when dentists are looking for a laser with soft-tissue applications, they will look for those with wavelengths that are properly absorbed by water, which have high peak power and an ability to control that power, including the use of very short pulses. This will create an environment for healing with the least amount of collateral damage.
Hard-Tissue Dental Lasers
In 1964, the ruby laser was used for hard-tissue ablation and eventually abandoned for dental hard-tissue preparation due to the thermal side effects of the wavelengths, which increased temperatures in dental pulp, caused microcracks, and carbonization.11 Excimer lasers (ultraviolet) and Erbium lasers (infrared) were developed in the late 1980s to provide better-quality temperature control and shallower penetration depths. In the 1990s, smaller devices were produced and new ablation techniques were established, accompanied by greater understanding of how to limit damage to the surrounding tissues.11
Erbium lasers can prepare enamel, dentin, caries, cementum, and bone. In addition, erbium and other hard-tissue lasers can be used for removing bone in crown-lengthening procedures for esthetic enhancements.6 They also can cut soft tissue.12 When used for hard-tissue applications, erbium lasers diminish or eradicate vibrations, the sound of dental drills, microfractures, and alleviate some of the distress that patients correlate with high-speed handpieces.12
The Nd:YAG laser is primarily considered a soft-tissue laser but does have a minimal hard-tissue application. Studies were conducted to determine which laser—the argon or the Nd:YAG—was more effective in caries preventative treatment within enamel. Results indicated that the argon laser was more successful than the Nd:YAG.13 However, the Nd:YAG cannot be used for preparing teeth.
Hard-tissue lasers have been used in conjunction with endodontics since 1971. Laser applications within endodontics have included pulp diagnosis, dental hypersensitivity, pulp capping and pulpotomy, root canal sterilization, root canal shaping, and obturation and apicectomy.14
Comparing the laser to a drill, Coluzzi notes that lasers produce no smear layer on dentin or bone, no microfracturing of enamel rods, and they disinfect the hard-tissue surface.
Diagnostic Lasers
Since their conception, diagnostic lasers have gradually become more low-tech and simultaneously more advanced. This is demonstrated within routine clinical examinations using magnification. Fiber-optic transillumination is visible to the naked eye, showing changes in color, shadowing, and craze lines within enamel and dentin.15
Laser-induced fluorescence uses laser light directed at hard dental tissue to determine if there will be a shift in the light wavelength being reflected back from the tooth, depending on the nature and density of the tissue. This spectral shift is not new to dentistry; the argon laser was the first device with these capabilities.16
Digital imaging fiber-optic transillumination (DIFOTI®, Electro-Optical Sciences, Inc., www.eosciences.com) uses a transilluminating camera to identify demineralization and capture images of the illuminated tooth using visible light. The examination can be performed in real time, with the camera moved around the patient’s mouth. This technique can also identify changes in density, even in interproximal areas.16
The challenge with transilluminating technologies is that despite showing zones of change, they are unable to provide data about whether or not the zone is active, inactive, or remineralizing from one single real-time examination.16 Yet, other research suggests that traditional explorer-based examinations provide little overall improvement in diagnostic accuracy compared to a thorough visual examination accomplished with careful drying of dentin, good light, and supplemental magnification. Rather, a sharp explorer used for diagnosing pit-and-fissure caries has low sensitivity and specificity, which could produce a higher rate of false positives, leading to increased rates of unnecessary treatments.15
According to Ron Kaminer, DDS, a private practitioner in New York, the benchmark for diagnostic lasers in dentistry was established with DIAGNOdent, a 655-nm cavity detection laser that uses fluorescence to quantify the presence of decay. The laser caries detection device helps identify pit-and-fissure lesions, provides quantitative data, and offers recommendations for initial surgical intervention for patients.16 DIAGNOdent helps with caries detection and performs successfully under different measurement conditions (eg, naturally wet, dried, and polished/dried surfaces).17
Within the last few years, however, companies such as Air Techniques (Spectra Caries Detection Aid; www.airtechniques.com) and Acteon Group (SOPROLIFE; www.acteongroup.com) have introduced other laser light devices that rely on fluorescence and filters within the unit to differentiate the presence of decay. Spectra uses a 405-nm blue-violet LED or diode laser and image-capturing technology in conjunction with analytical software to capture images of demineralized tooth structure. Areas in green, blue, red, orange, and yellow help objectively provide data regarding the progression of carious lesions or the effectiveness of remineralization therapy.16
"For example, if there is decay in the tooth and there’s Streptococci mutans there, the light will fluoresce the area red and the rest of the tooth will be green, giving the doctor the ability to somewhat be selective during the examination,” Kaminer explains. "We can therefore be more minimally invasive and selective through the use of fluorescent technology, rather than excavating a whole tooth if decay was on the occlusal.”
Acteon’s SOPROLIFE also uses fluorescence to identify decay as red both intraoperatively and preoperatively. During excavation, it can be used to determine if decay is still present and, if so, to direct removal during the operative process.
Another laser diagnostic device is Caries I.D.™ (DENTSPLY Professional, www.cariesid.com), a handheld device and diode/LED laser that uses green wavelength light to identify demineralized areas. This Caries I.D. works by color change, so if a demineralized zone is displayed, the color turns red and beeps. The tip, which is lightweight and portable, can move in light contact with tooth surfaces.16
Lasers for Scanning Intraoral Impressions
With digital impression-taking techniques, dental professionals can circumvent traditional impressions and the materials, time constraints, and handling restrictions linked with them.7 Intraoral scanners based on laser technology oftentimes yield excellent accuracy and a more relaxing experience for patients, as well as a more productive workflow for the dental office.7 However, unless the practice is fabricating restorations in office, realizing the full potential of digital impression-taking requires the dental practice to work with laboratories that can work in a 3-D format so that conventional fabrication skills can be applied in a digital format.18
"Scanning is definitely more accurate using dental laser technology than with conventional crown-and-bridge impression materials” explains Marty Jablow, DMD, a private practitioner in Woodbridge, New Jersey.
A new range of digital intraoral scanners has recently become available, and new technology is expected to continually be introduced.19 Eventually, traditional impression-making will become obsolete, with intraoral scanners rising to the new standard and a new generation of dentists trained in the innovative technology.18
"New laser impression scanners incorporate a series of two lasers similar to what’s used in topography that is very accurate,” explains Goodman. "By passing a wand over the teeth or impression area, the laser produces a topographical reading in great detail of the crown preparation, or of whatever you’re working on.”
Several scanning impression-taking lasers are available. The intraoral impression-taking scanner for the E4D Dentist System produces 3D images of the oral environment that can allow clinicians to view preparations, surrounding areas, and margins. The Lava™ Chairside Oral Scanner (C.O.S.) (3M ESPE, www.3mespe.com), which can be used in conjunction with other systems, scans a prepared tooth and electronically transfers the data to a manufacturing center, where fabricated models of individual teeth and arches are fabricated. The iTero™ system (Cadent, www.cadent.biz/itero) likewise captures intraoral images, creates a digitized representation of a prepared tooth, and then transfers the information to a manufacturing center for fabrication of a working model that is sent to the prescribed dental laboratory.18
When it comes to digital impression-taking systems, clinical performance depends on the marginal fit and integrity of the restorations and should be the foundation for selecting a particular system.18 CAD/CAM systems are equipped with various improved technologies to facilitate intraoral impression scanning, such as an automatic image-capturing system that verifies the focus of the subject and instantaneously saves the image, eliminating the need to "click” a button or pedal. There is also an anti-shake function with a broad range depth of field inside the auto-capture camera. However, the operating field must still be well isolated during the imaging process to record accurately record margins.9
Among the limitations of some scanning impression devices, red laser technology cannot scan a complete image. A speckled image can ensue and is a consequence of incomplete laser light reflection, requiring multiple pictures to capture the entire tooth.18
A previous disadvantage of the intraoral scanner impressions associated with some CAD/CAM systems was the sensitivity of reflective titanium dioxide powdering step. This step often resulted in inappropriate images and made use of this technology difficult.18 Newer generations of the technology (eg, CEREC AC, Sirona Dental Systems) are less sensitive to underpowered areas and enable operators to capture images much quicker.18 The newly released Sirona Onmicam (Sirona Dental Systems) will replace the CEREC AC, and does not require any powder.
The Lava C.O.S. System uses "3D-in-Motion” continuous 3D video. However, the video file is very large (in terms of gigabytes), requiring an overnight download/upload to the central facility.18
Low Level Lasers
Low-level laser therapy (LLLT), otherwise known as photobiomodulation, has been a treatment modality for the past 30 years. With most research having been performed outside of the United States, Jablow says low-level laser therapy or cold laser therapy has been used for wound healing and muscle repair.
LLLT uses light energy from adenosine triphosphate (ATP) to stimulate the body’s biological responses. This increases cellular energy and alterations in the cell membrane, resulting in pain relief, wound healing, muscle relaxation, immune system modulation, and nerve regeneration.20
Used for decades throughout the world, low-level laser therapy has been incorporated in dental, medical, veterinary, and physiotherapy professions.21 Studies show that by using acupuncture and low-level infrared laser therapy, TMD patients exhibit lower levels of pain and sensitivity to palpation.22 LLLT also has FDA clearance for treating and managing oral mucositis.
While low-level laser therapy has been used with soft tissues, there has recently been added interest in tooth-related or hard-tissue applications, such as treating dentin hypersensitivity and pain arising from the periodontal ligament.23 Research shows laser therapy is advantageous compared to topical medicaments in treating dentin hypersensitivity.24
Controlled clinical studies reveal that while LLLT is effective in treating specific soft-tissue applications, it is not effective in every scenario.23 Research is still needed regarding the mechanisms of low-level laser therapy, as well as for detecting the therapeutic window and how to properly employ cellular phenomena to reach treatment objectives.21
Laser Education and Certification
As with all technologies, it is imperative that all dental professionals have thorough and comprehensive training and understanding of the technology’s functionalities and applications. With dental lasers, it’s also imperative that the entire staff is appropriately trained on the safe and effective use of that device, understand safety standards and government regulations, as well as its applications and limitations, Benjamin explains.
Among the important considerations for dental practices to follow when incorporating dental lasers is the requirement of having a designated Laser Safety Officer (LSO), and often referred to as the LSO in all facilities where a class 3 or 4 laser is in use. It is the LSO’s responsibility to establish the office’s laser procedural and administrative controls and protocols to ensure that the laser healthcare systems are used in a safe and effective manner. Some of the primary duties of the LSO are defining the nominal hazard zone (the danger zone) when a laser is in use and to ensure that all of the practice’s staff members have been adequately educated and trained on laser use and safety to the appropriate level for the duties they provide. A partial list of some of the other LSO’s responsibilities include regular inspection of the laser systems in use and the ancillary components such as labels, signs, and ensuring that laser protective eyewear is appropriate and in good repair; and that ensuring that standards for laser safety and infection control protocols are being followed.
"There is much confusion among dental professionals about the type of education required for using class 3B and 4 lasers (therapeutic and surgical lasers) in the dental practice. Regulations on whether a dental hygienist may or may not use a laser, and the type of training required, varies from state to state,” Benjamin elaborates. "It is imperative that all clinicians refer to their state’s dental practice act regarding the utilization, education required, and scope of practice before using a laser.”
Regardless of whether a clinician’s state dental board requires laser-specific education and training, the American National Standard (ANSI) for the Safe Use of Lasers Z136.1-2007 and American National Standard (ANSI) for the Safe Use of Lasers in Health Care Z136.3-2011 states that licensed dental professionals must be properly trained and use a laser within their scope of practice and in a manner where the procedure is safe, effective, and consistent with the clinician’s education, training, and experience; the hands-on training needs to be focused specifically for the device the clinician is using and the procedures being performed. The curriculum guidelines established by the Academy of Laser Dentistry (ALD) is the foundation for the content of the information provided in these training courses and is cited in the z136.3 standard. The ANSI standard is considered the standard of care and education that healthcare professionals are held accountable to in the case of medical-legal action, making it imperative that all clinicians receive device-specific hands-on training. Clinicians are encouraged to think of the legal implications of stating that they learned how to perform laser surgery on the Internet, Benjamin cautions.
"There is also a great amount of confusion about what these educational experiences should be called. The ADA CERP and AGD PACE continuing education programs forbid the use of the term "certification” for any continuing dental education course, as this term is reserved specifically for the nine ADA CODA-approved specialties (eg, endodontics, periodontics, prosthodontics, etc.),” Benjamin continues. "The reason is to protect the public from misleading statements and avoid misinterpretation by the public or professional colleagues. Appropriate wording following the ADA CERP and AGD PACE guidelines is similar to the "verification of completion of a training course.”
"Most companies offer some training, although some just have a DVD and others have additional hands-on simulations,” explains Coluzzi. "A few states require different courses for re-licensure and other states are considering similar curriculum.”
Coluzzi’s personal opinion after using different lasers for 22 years is that dentists considering purchasing lasers should have a basic understanding of laser fundamentals, be very familiar with the operation of their instruments, take a hands-on simulation course first, and then continue the educational process at every opportunity. They also should obtain a competency "certificate,” preferably from academia, not from a company.
"I would certainly encourage dentists and team members to review their own state’s dental practice act before they consider using a laser, because you want to ensure you’re within your scope of practice,” emphasizes Charles R. Hoopingarner, DDS, past chairman of regulatory affairs for the ALD. "Laser courses for training are given at many universities and at many dental association meetings, and the American Dental Association every year has several courses in proper use of dental lasers.”
He also highly recommends courses through the ALD, which aren’t associated with any particular manufacturer and whose mission is to study and learn how to use lasers better and more effectively. Courses organized and offered by the ALD ensure safe and optimum use of various wavelengths and lasers, he says.
Conclusion
From soft-tissue lasers to those designed for hard-tissue applications, and from lasers used for dental diagnostics to those approved for marketing for therapeutic indications, dental lasers today can serve many beneficial roles when used by properly trained professionals.
"Remember that there is more than one way to do things,” advises Francis Serio, DMD, MS, MBA, interim vice dean and professor and associate dean for clinical affairs at East Carolina University School of Dental Medicine. "Whatever laser you buy, it is incumbent upon you to understand everything you need to about that laser, how it works, what the wavelength is, what it will do for you, and what it will not do for you.”
That said, considerable progress remains to be achieved and clinical research conducted in order for dental lasers to reach their full potential within the profession. As progress, clinical experience, and scientific investigations continue, dental lasers may contribute to the development of new dental adhesives and composite systems, new methods for managing caries, and new endodontic treatments, among other advancements.1
"We’ve gone from about 5% of the profession using lasers to about 25%, and it’s growing rapidly. Many of the newer diode lasers are being pulsed or have on/off settings that allow procedures to be done even more comfortably, and I think we’re going to see much expansion in that technology over the next several years,” Hoopingarner predicts. "There has even been research conducted into using lasers to re-mineralize enamel and eliminate enamel defects for caries prevention. We’re just starting to see some of the non-traditional benefits of lasers come into view, and so it’s going to be an exciting next 10 or 15 years.”
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