I was initially excited to read Drs. Douglas Dederich and Ronald Bushick’s article, "Lasers in Dentistry: Separating Science From Hype," in February JADA. However, after careful scrutiny of the text, I wish to offer some comments and an invitation.
By way of disclosure, I am one of the past presidents of the Academy of Laser Dentistry, or ALD, an 11-year-old international organization of clinicians, academicians and researchers. I have been honored to have presented on lasers at an ADA annual session, and also to have shared the podium several times with one of the authors of the article, Dr. Dederich. I also have just completed a four-year term as co-editor of Wavelengths, the quarterly journal of the ALD.
The call for a scientific discussion about dental lasers is quite noble; the abstract and several of the opening paragraphs serve that end well. However, as the article continues, there are several statements that are misleading and/or inaccurate. There are some sentences that state opinions with no basis in fact, and there are several references that do not provide any reinforcement to the written words.
Here are a few examples:
The statement that, "the [Nd:YAG laser] has the greatest depth of penetration" is untrue, incomplete and an opinion. Since no reference was given for the statement, I’ll offer one from a scientific syllabus1 showing an absorption depth in water of an 800-nanometer diode laser to be almost 10 times greater than that of the Nd:YAG.
The statement that Nd:YAG laser light damages the pulp is backed up by two references.2,3 Careful reading of those citations shows an experiment using a cat cuspid and holding the Nd:YAG laser on the enamel at right angles to the surface with tremendous power density, way more than would be used for normal soft-tissue excisional surgery. To extrapolate those results to humans is ludicrous. In fact, the author of the article concludes that the "spot irradiation with the laser produced severe damage in the pulp tissue in a dose-dependent manner." There are two points here: 1) the Nd:YAG laser has no indication for use on healthy enamel (meaning, according to the manufacturer’s direction, it must not be used in that manner); and 2) the ALD consistently teaches clinicians to prudently choose the lowest power to accomplish the treatment objective.
The Nd:YAG fiber does not act as a hot tip, which once again is an opinion. The fact is that the temperature at the tip of an Nd:YAG fiber does not appreciably rise from room temperature.4 Surgical byproduct debris can accumulate on the tip of any wavelength laser, and the clinician must remove it before continuing.
The wound healing statement about Nd:YAG is from a study about vocal chord epithelial ablation with a CO2 laser.5 It has nothing to do with intraoral use of the Nd:YAG device, and is very embarrassing for a scientific journal article.
The melting or alteration of the Er,Cr:YSGG calcium: phosphorus ratio references6,7 are in vitro animal studies, and both of those conclusions state that much more work is necessary before human significance is found.
The statement about Er:YAG comfort has a reference,8 but the Er,CR:YSGG does not, again offering an opinion.
Three paragraphs are devoted to a gallium-arsenide laser with a wavelength of 904 nm. That particular laser is a low-level laser, with a power output of about 4 milliwatts and is used to treat inflammation. The dental surgical diode lasers are either aluminum-gallium-arsenide, emitting a wavelength of approximately 830 nm, or indium-gallium-arsenide, emitting a wavelength of 980 nm. This is a serious manuscript error, and it is repeated in the "Characteristics of Lasers Used in Dentistry" table.
The discussion section offers several opinions about the Er,Cr:YSGG device, without mentioning that the Er:YAG laser is also used with the same exact water spray.
The conclusion belies the "science" of the article, since there are several well-referenced sentences (in spite of those I’ve pointed out above), showing superior results.
My invitation to JADA is to offer the wealth of knowledge of the Academy of Laser Dentistry and its Communications Committee to assist in reviewing, or perhaps authoring, any articles about the use of lasers in dentistry. JADA should publish information that is scientifically and editorially correct. I’m proud of my ADA membership, but very disappointed in this article.
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