Oral Health Group
Feature

Lasers in Dentistry: An Application That Found its Purpose

March 1, 2011
by Dr. Glenn A. van As


INTRODUCTION

In 2008, Dr. Gordon Christensen wrote an article in JADA comparing the soft tissue cutting ability of diode lasers versus that of electrosurgery (radiosurgery) units.1 In that article, he compared these two technologies against each other, and cited advantages and disadvantages of each alternative. In this article, Christensen cited that although both technologies were effective that lasers were more accepted by the general public, and that diode lasers offered advantages over electrosurge including being able to be used around metal objects (amalgam, gold, braces and implants), not harming hard tissue (bone) or soft tissue (pulp) and that lasers are antibacterial and could be used more often with only topical anesthetic. The big negative cited by Dr. Christensen was that at that time, electrosurgical units were “far less expensive than the least expensive diode lasers” and he questioned whether “the advantages of the diode laser wer significant enough to compensate for the additional cost.”

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Now, less than three years later, a tremendous surge in diode laser interest has occurred. This is in due in no small part to the drop in the price range of diode lasers from around the 10-12 thousand dollars in 2008 for the least expensive diode semiconductor lasers to a price range of CD$3000.00 (AMD Laser’s Picasso Lite and Picasso World disrtibuted in Canada by Oral Science – www.oralscience.ca/en). This dramatic price drop of over 75% in the price of these units has caused many clinicians to look at soft tissue lasers as an alternative to traditional methodologies. As more dentists discover the cost effectiveness of soft tissue lasers, there has been an additional growth in the discovery of clinical situations where lasers offer either unparalleled ease of use.

Soft Tissue Laser Applications

Diode lasers are popular for many simple soft tissue procedures including gingivectomies, crown troughing, frenectomies, fibroma removal and the treatment of oral lesions (Aphthous ulcers, Herpetic lesions, denture sore spots). These simple procedures are made easier with the laser, in that they allow for soft tissue surgery to be done in a clean bloodless field with less reliance on anesthetic as compared to either scalpel or electrosurgery. Postoperative pain and post operative inflammation are purported to be less with lasers than with electrosurgery.2-5 Many of the procedures that can be completed by the dentist are similar to those that can be done with traditional methodologies but with less reliance on anesthetic, at times improved healing, and with greater visibility due to the dry field that is provided. Given todays emphasis on resin bonding for so many of our cosmetic procedures it is extremely valuable to complete soft tissue procedures in a dry field.

Tissue Troughing with the diode laser

The diode laser has recently become a popular technology as an alternative for tissue management compared to the traditional methodology of placing a single or double retraction cord in the sulcus or in using electrosurge (radiosurge). The diode laser can be used in almost all instances to produce gingival retraction as an alternative to cord with excellent results both in terms of tissue management (retraction), and in margin delineation for the laboratory. Diode lasers, unlike electrosurgical units where recession can be an issue, as can postoperative pain, offer the clinician the ability to precisely remove overhanging, inflamed tissue while creating a gingival trough that is not likely to cause damage to bone, cementum, or pulp tissue like electrosurgical units can.

As with any technology, there is a short learning curve to understanding how to use soft tissue lasers. All lasers are end cutting so the typical dentist needs to learn how to make slower and shorter movements with the tip of the laser. Unlike a bur or scalpel where the sides of the instrument can be used in a dragging motion, lasers require a deft and soft touch with short brush like strokes using the tip to ablate tissue. Once the short learning curve is conquered, many clinicians will replace cord and use the laser almost exclusively for tissue management for their indirect restorations in their practice.

The safety of lasers for gingival retraction procedures has been documented in the literature by Gherlone et al6 who found that lasers (diode and NdYAG) when compared to the conventional techniques of double cord or electrosurgery yielded less gingival bleeding, and also less gingival recession. Their interesting conclusion was that although both techniques are satisfactory that the laser techniques were in fact “less traumatic to the periodontal tissues”.

In situations where esthetics is crucial and where thin tissue genotypes exist, or if the patient is changing the color of the tooth significantly from the existing stump shade, then extra care must be taken when using the diode to trough for impressions.. In the author’s experience, with the introduction of adequate levels of magnification (e.g. Loupes of 4.0X or greater or an operating microscope) and the careful use of lower powers on the diode laser (for example 0.6-0.9 watts of power in Continuous Wave), the diode laser tissue management can be done with confidence in not having gingival recession occur post-operatively, and often can be done with only topical anesthetics which can be useful when troughing around endodontically treated teeth.

Diode Laser Usage around Metals

The diode laser has an added benefit of being able to be used with less concern over damage to hard or soft dental tissues, or damage to dental prosthesis that can occur with the less expensive monopolar electrosurgery units.7-9 The diode laser can be used safely around metal including amalgam, braces, gold, and implants without fear of iatrogenic damage to the implant or bone.10-11 In new research there are suggestions that the diode lasers when used at lower levels of power (Low Level Laser Therapy) may in fact improve the early healing of tissues and in also be used in cases of peri-implantitis.12-17 Lasers can be used in several areas of implant dentistry including initial site preparation with a surgical stent or removing redundant tissue during implant placement. At 2nd stage, during the uncovering of the implant, lasers can be used to safely remove overlying tissue in a dry field with a high degree of visibility. Lasers can be used to provide a clear view of the cover screw after the typical healing period for osseointegration. In addition, at times soft tissue and even bone (in subcrestal implant placement) will be present on top of the implant itself, after removal of the cover screw. In these cases, soft tissue diode lasers can be used to remove overlying tissue and erbium hard tissue lasers can be used to remove bone safely to allow for easier impression taking. Soft tissue can be removed often with only topical anesthetic, and it is vital to not take an accurate impression of the implant to prevent chronic inflammation that can occur if soft tissue is not completely removed off the implant fixture. Additionally, soft tissue can impede the complete seating of the implant crown during the final stage of the implant restoration. Again the simplicity and safety of using a laser around both metal and Zirconium structures can make a difficult scenario much easier (Figs. 10-14). Finally, lasers are becoming more commonly used to help treat the failing implant by removing granulation tissue, being bactericidal, selectively used to remove hydroxyapatite coatings all of which can help to try and salvage cases where potential loss of the implant itself is possible.

Treatment of Oral Lesions

One of the advantages of a diode laser is the ability to help both palliatively and in lessening the recurrence of oral lesions including Recurrent Aphthous Ulcers (RAU), a
nd Herpetic Lesions. (Figs. 15-21) Research has shown that lasers can be safely used to treat these lesions,18-19 and in addition it is possible that if caught early during the prodromal stage that the lesions can be aborted or significantly reduced in terms of length of time they are present.20 In addition, its been the authors experience that once treated with the laser, the lesions are often less likely to reappear in the same area.

Hemangiomas (often referred to as Venous Lake lesions) of the lower lip have been traditionally one of the more difficult lesions to treat. There is a growing body of evidence to show that a diode laser can often completely eliminate these purplish lesions in one single treatment, often without an injection.21-24

Cosmetic “Smile Lifts” and Removal of Veneers

DIode Lasers have been shown to be effective in cosmetic dentistry cases in that they are capable of recontouring gingiva in conjunction with cosmetic dentistry.25-28 Care must be taken to ensure that adequate biologic width is retained after the gingivectomies are completed. Typically, only a small amount of keratinized tissue can be removed without creating a problem where continual inflammation of the final restorative result occurs. Therefore diode lasers can usually only be used to recontour small asymmetries.

One benefit of hard tissue erbium lasers is their ability to be used to assist in “gummy smile” cases where an excessive or asymmetrical amount of soft tissue appears in a smile. All too often, we as dentists focus on the “white” parts of the smile and fail to observe gingival asymmetries (pink part of the smile) which, if corrected, could significantly improve the overall aesthetic outcome of the case. Conventional periodontal surgery consists of full or partial thickness flaps, and osseous surgery to remove bone, followed by sutures and a minimum of 12-16 weeks of healing. There is nothing wrong with viewing the overall architecture of the underlying biology of bone, roots and soft tissue, however there are times when more minimally invasive techniques may be used with equally impressive results and with perhaps a much quicker healing time. Osseous surgery either in a full flap scenario or at times with closed flap laser techniques using both diode and erbium lasers, can provide tremendous results for the patient with shortened healing times.29-31

In addition, with the fact that porcelain veneers have been available for almost 3 decades32-33 now there are instances where removal and replacement of these veneers is necessary. Due to the nature of the tremendous color matching abilities of both resin bonding cements and the veneers themselves, the removal of veneers without damage to the underlying natural tooth can be difficult. Erbium lasers can be used with energy settings of around 4-5 watts to remove many porcelain veneers, often within 30 seconds. Many times the veneers will fracture and fall off with the erbium laser or they are loosened by the laser and then they can be removed with a curette. The mechanism of action is suspected to be that the erbium laser interacts with the OH molecule in the silane bond. With this in mind, often the veneers are removed while leaving the cement loosened on the tooth. This procedure is both predictable, efficient, safe and documented now in the literature.34-35 In addition, the removal of veneers is documented in videos online by several clinicians including this author ( http:// www.youtube.com/watch?v=wofVKNpZHKg) and in the case below which shows a combination of erbium laser crown lengthening and subsequent veneer removal with the same hard tissue laser. (http://www.youtube.com/watch?)

Anti-bacterial Capabilities of Lasers

Many articles in the literature have demonstrated the tremendous ability of all lasers to be both anti-bacterial and they can even have anti-fungal reduction capabilities.36-43 The bacterial reduction feature alone makes lasers effective and desirable in many areas in the oral cavity where the risk of postoperative infection may be reduced with lasers. Particular interest is now occurring in the role of lasers in endodontic, periodontic and peri-implantitis cases where the need to reduce bacterial loads without such a great deal of reliance on antibiotics might be exciting. Although more research is needed on how the bactericidal capabilities of the diode laser might be beneficial in these areas, there is no debating that all lasers can help healing through decreasing the risk of infection through laser light alone. In addition, there is a growing body of research has demonstrated that the risk of high bacterial loads in periodontal pockets and in particular in endodontics situations may be reduced by lasers. These newer articles in the last several years have implications for improving traditional methodologies locally where used, and in helping to reduce the potential greater systemic health risks generally. The role of lasers continues to be researched today, but present research has shown that diode and erbium lasers can be used safely within root canals with minimal fear of developing iatrogenic complications when conservative settings are used44-51 (Figs. 29-32).

Conclusion

In the last three years, diode lasers have become a vital part of many dental practices for their cost effective solution to many clinical problems that are seen daily in private practice. The laser as an “electrosurgery replacement” has become a reality with these newer units which provide numerous advantages to every day dentistry.

The advantages of diode lasers tissue troughing as a replacement in many instances for cord, in being safely used around metals (implants, amalgam, gold, orthodontic brackets) cannot be overlooked. OH

Dr. Glenn A. van As graduated from UBC Faculty of Dentistry in 1987 and has maintained a full-time private practice emphasizing cosmetic, laser and microscopic dentistry since then. He is an active member of the Academy of Laser Dentistry (ALD), and former Leon Goldman award winner for clinical excellence in the field of laser dentistry (2006). He discloses an affiliation with AMD Lasers (www.amdlasers.com), Global Microscopes ( www.globalsurgical.com) and Oral Science (http://www.oralscience.ca/en/). References available upon request


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