The development of dental laser technology can be compared to the evolution of rotary dental handpieces. When faced with the opportunity to move from a high-speed rotary handpiece or even soft-tissue laser to hard-tissue laser, I have witnessed some resistance from my colleagues. I would imagine that similar retorts were offered in the 1950s, when the new Borden air rotor (the first air-turbine handpiece) was introduced as an alternative to its belt-driven counterparts. Despite the obvious benefits to both the dentist and patient in moving from 600 rpm to 250,000 rpm, our predecessors were slow to embrace the new technology of air-driven devices.
Today, we are faced with the introduction of a new paradigm. During the past two and a half decades, forward-thinking clinicians have added soft- tissue lasers to their high-tech armamentaria. I believe it is now time to move forward to the next logical step in patient care; an all-tissue dental laser. In this piece, we will look specifically at what most laser dentists consider to be the most critical reasons to perform laserassisted dentistry in general dental practice.
Fig. 1-Etched YSGG laser preparation, including caries removal using a low-speed round bur. This can routinely be completed without local anesthetic
Much has already been published in the dental literature on the history and fundamentals of lasers in dentistry, however, a brief overview of hard-tissue laser wavelengths is warranted.1,2 Most soft-tissue lasers that are commercially available reside in the range from 800 nm to 1000 nm in the electromagnetic spectrum. The exception to this is carbon dioxide lasers around 10,600 nm.
Fig. 2-Finished composite restoration of a "laser filling."
Hard-tissue lasers, on the other hand, operate in the midinfrared range of 3,000 nm. This article relates specifically to the Er,Cr:YSGG (Waterlase MD, Biolase Technology, Irvine, CA), which operates at 2780 nm. This wavelength is highly absorbed by both water and hydroxyapatite, but has little effect in pigment.
Fig. 3 – Class II cavity preparation completed using the YSGG laser only. Note that there is no damage to the adjacent tooth. With proper training and practice, laser cavity preparations can be precisely refined.
As general dentists, much of our day is consumed with the cutting of enamel and dentin. The YSGG laser is well suited for this purpose.3,4 First, cutting is produced without vibration, unlike cutting with a rotary handpiece. This eliminates all vibratory pain stimuli to the tooth, which is useful in general, but especially beneficial in teeth exhibiting pulpitis, which is often painful to treat, even under local anesthetic.5 The precise cutting produced with the YSGG laser has been shown to leave no traces of a smear layer on the prepared surface.6 Absence of any debris allows for completely open dentinal tubules and more complete adhesion of restorative materials, resulting in longerlasting restorations with less postoperative sensitivity.7,8 Because of the laser’s ability to strengthen the peritubular dentin, researchers have found that there is a decrease in the risk of recurrent caries in laser-prepared cavity preparations.9 In addition, numerous clinicians have reported that there is an analgesic effect when using a laser.
Fig. 4-Immediate post-op view of surgery completed without local anesthesia. Note hemostasis achieved with a Er,Cr:YSGG laser.
Although the mechanism of action has not yet been adequately identified, there is ongoing independent research to help explain this phenomenon and anecdotal evidence abounds. Although dubbed “hard-tissue” lasers, what makes this device of such great value is the fact that it can also be used very effectively to perform soft-tissue procedures, including incisions, excisions,10 and periodontal and bone surgery. The triple role makes this technology especially valuable to a general practice that already offers, or would like to offer, procedures that require cutting both hard- and soft-tissues plus bone. Switching from one tissue type to the other is easily accomplished with only a small change in settings rather than a replacement of handpiece or fiber tip. Thus, moving from hard- to soft-tissue to bone— and back again—is a highly ergonomic function.
FIg. 5-Presentation at one week post-op.
Earlier in this discussion it was stated that the YSGG laser was not well absorbed into pigment. Since that is precisely how softtissue lasers affect the tissue, there may be some confusion at this time. Soft tissue is composed almost entirely of water, placing it well within the effective range for absorption of the “hard-tissue” laser wavelength. Water absorbs the laser energy almost completely. As a result, there is a rise in tissue temperature and then vaporization, making ablation of soft tissue by erbium lasers very efficient.
Fig. 6-Severe ankyloglossia preoperative view.
The Waterlase MD offers an alternative pulse mode specifically created with soft tissue in mind. This second pulse duration, which is as much as ten times the length of the hard-tissue cutting pulse, increases the energy applied to the tissue surface. The increase in total energy coupled with a shorter thermal relaxation time provides the ability to effectively achieve hemostasis in soft-tissue procedures (Figs. 4 & 7).
Fig. 7-Immediately postoperative view of lingual frenulectomy completed without local anesthetic.
The realm of using an all-tissue laser has changed the dental laser landscape forever. There are valid reasons to owning more than one laser wavelength, however, the benefits of adding an “all-tissue” laser wavelength to a contemporary general practice are many. Improved efficiency and better postoperative outcomes, fewer adverse side-effects, along with improved clinical results, higher patient satisfaction, and an increased competitive edge, are only a few ways a laser will positively manifest itself in your business. Practice growth, patient influx, and the renewed enjoyment from my profession that I personally have experienced, is a testament to the positive effect lasers have had upon my dental practice.
I truly hope that this brief discussion will pique your curiosity enough for you to set your belt-driven handpiece aside and explore the possibilities an all-tissue laser will offer to you, your patients, and your practice.
Dr. Christopher Walinski is Adjunct Faculty at The Ohio State University College of Dentistry; has a part-time private practice; and is the program director for the New England Laser Training Center in Fall River, Massachusetts. His e-mail address is gobux27@yahoo.com.
References
1. Walsh, LJ. The current status of laser applications in dentistry. Aust Dent J. 2003 Sep;48(3):146-55; quiz 198. 2. Stabholz, A, et al. The use of lasers in dentistry: principles of operation and clinical applications. Compend Contin Educ Dent. 2003 Dec;24(12):935-48; quiz 949. 3. Kimura, Y, et al. Effects of Er, Cr:YSGG laser irradiation on root surface: morphological and atomic analytic studies. J Clin Laser Med Surg. 2001 Apr;19(2):69-72. 4. Hossain, M, et al. Effects of Er, Cr:YSGG laser irradiation in human enamel and dentin: ablation and morphological studies. J Clin Laser Med Surg. 1999;17(4):155-9. 5. Takamori, K, et al. Basic study on vibrations during tooth preparations caused by high-speed drilling and Er:YAG laser irradiation. Lasers Surg Med. 2003;32(1):25-31. 6. Altundasar, E, et al. Ultramorphological and histochemical changes after Er, Cr:YSGG laser irradiation and two different irrigation regimes. J Endod. 2006 May;32(5):465-8. 7. Sung, EC, et al. Composite resin bond strength to primary dentin prepared with Er,Cr:YSGG laser. J Clin Pediatr Dent. 2005 Fall;30(1);45-9. 8. Schwarz, F, et al. Desensitizing effects of an Er:YAG laser on hypersensitive dentine. J Clin Periodontol. 2002 Mar;29(3):211-5. 9. Hossain, M, et al. A study on acquired acid resistance of enamel and dentin irradiated by Er,Cr:YSGG laser. J Clin Laser Med Surg. 2001 June;19(3):159-63. 10. Walinski, CJ. Irritation fibroma removal: a comparison of two laser wavelengths. General Dentistry 2004 May-June;52(3):236-8.