Dederich 204-212.qxd

Background. During the last two
decades, much has been written
in both the scientific litera-
Lasers in dentistry

contouring, caries removal and bleaching.
Overview. Almost one-third of patients
surveyed by the American Dental Associa-
tion in the late 1990s thought it was very
important that their dentists have lasers,
which could put pressure on dentists to
invest in this tool to attract patients. The
Lasers have been used in the dental arena for
more than 20 years—enough time for dentiststo learn, at least in a basic sense, what thistechnology legitimately can do for us as clini- cians and for our patients. However, many practitioners still are unsure about the unique contribu- behind their applications in dentistry.
Conclusion and Clinical
Implications. Although lasers do have
legitimate uses in dentistry, they do not
Before Public perception. In addition to the specu-
take the place of any of the more conven- investing in a lation in professional circles about the contri-
tional tools in the dentist’s armamentarium.
bution of lasers to dentistry, dentists must laser, dentists
Before investing in a laser, dentists should respond to patient’s inquiries and perceptions should fully
about laser technology and its usefulness. A understand the
the various types, including what the scien- differences
tific literature says about their applications.
Dental Association indicates that 31 percent between the of adults consider it very important for a
various types. dental practice to have a laser, 30 percent con-
sider it important and 21 percent consider itsomewhat important.1 Although this survey does not discriminate between laser types and applica- tions, it does highlight the marketability of lasers in dentistry. For some dentists, such public perception, and the perceived marketability that such a tool could lend one’s practice, could create pressure to rush toward Although nearly two-thirds of consumers surveyed1 would like to see lasers available for use in their den- tists’ offices, only about 3.5 percent of dentists surveyed looking for a clinical use for it. The first by the ADA in 2000 used lasers in their practices.2 This relatively small percentage may be due, in part, to the ability to achieve equivalent clinical results with less Philosophy of care. In dentistry, decisions about
incorporating new technologies depend, in part, on one’s Practical Science is prepared by the ADA Council on Scientific Affairs and Division of Science, in coopera-
tion with The Journal of the American Dental Association. The mission of Practical Science is to spotlight
what is known, scientifically, about the issues and challenges facing today’s practicing dentists.

Copyright 2004 American Dental Association. All rights reserved.
technology when decisions are being made about or FDA, but how many dentists understand what In addition, dentists should feel free to FDA clearance. This clearance enables com-
abandon a tool or technology if a new one comes panies to expedite the process of entry to the along that can better serve patients’ needs, but marketplace for products the FDA considers sim- practical matters such as cost and the user’s ilar to devices already on the market. Often, this learning curve can limit this freedom. Thus, after considering the time and money that must be approval, which requires multiple-site testing to invested to make a technology work in the prac- demonstrate safety and efficacy. To obtain 510(k) tice, dentists should rely on the best available sci- clearance, manufacturers must demonstrate only entific evidence when making a decision to pur- results equivalent to those of an existing, chase and incorporate new technologies. Before approved technology.7 From the scientific per- making a commitment, they should consider spective, however, such an abbreviated process what the reliable scientific literature indicates about the technology’s safety, efficacy and State dental boards. Other examples of regu-
Dentists should
consider a number
of factors when
deciding whether to
incorporate laser
systems into their
ment in capital and the need to learn how to use the final word on the subject. Not all therapies the equipment. Dentists and patients also should allowed by state dental boards truly represent realize that laser-induced tissue trauma to the the standard of care. The decision regarding surgical site can add several more days to the whether a treatment modality represents the healing process, and can cause dramatically standard of care is left to good science and the abnormal appearances for up to 10 to 14 days profession itself. We hope and expect that board decisions will reflect the best of science and our This article is an effort to communicate to the profession the uses for lasers in dentistry that The standards of good science, in contrast to enjoy the best scientific support, and to clarify the specific and unique needs and responsibilities where the weaknesses lie for other promoted of the FDA, make a distinction that the FDA’s uses. It is not intended to be a comprehensive lit- 510(k) clearance process does not. Good science erature review; rather, it is meant to arm the distinguishes between stand-alone comparisons practitioner with good science that he or she can and comparisons that use adjunctive therapies.
use when deciding whether to invest in lasers. For example, if one claimed that a laser couldplane roots as well as could curettes, the study GOVERNMENT REGULATION VERSUS
design would compare use of the laser alone SCIENTIFIC STANDARDS
versus the curette alone for root planing. In this The number of regulatory agencies in our country case, the laser would have to produce an “equiva- and their influence on our lives are tremendous, lent” result for this use of the technology to be which can cause some confusion regarding the scientifically justified (assuming safety concerns meaning of some of their proclamations. For example, many lasers now sold in the United By contrast, if a laser is recommended for an States have a 510(k) clearance for marketing adjunctive procedure, such as subgingival curet- through the U.S. Food and Drug Administration, tage after scaling and root planing, the standard Copyright 2004 American Dental Association. All rights reserved.
that must be met is one of “superiority.” This credible information available. We also must be means that after scaling and root planing, the willing to modify our practices to conform to this laser must demonstrate added benefit over new information as it becomes available. We rec- scaling and root planing alone. This standard also ommend caution in cases in which direct evidence applies to other adjunctive therapies, such as of safety, efficacy and effectiveness is not local drug delivery or administration of subantimicrobial-dose doxycycline when used inconjunction with scaling and root planing.

Lasers produce light energy within a narrow fre- Safety. When evaluating any product such as
quency range. For most practical purposes, the lasers for use in patient treatment, one must be light produced by lasers can be considered to be sure that it succeeds in three arenas: safety, effi- monochromatic. Typically, lasers are named cacy and effectiveness. Safety requires that collat- according to the active element within them that eral damage be assessed histologically at several goes through the stimulated quantum transitions, The wavelength of
the light is the
primary determinant
of the degree to
which the light is
absorbed in the
target material.
Efficacy. Efficacy is the degree
beneficial result for the patient under the con- modifications can shift, within limits, the wave- trolled conditions seen in a clinical trial. Ethi- cally, laser treatment must show efficacy and an Laser energy penetration. The wavelength
acceptable risk-benefit ratio for it to be put for- of the light is the primary determinant of the degree to which the light is absorbed in the target Effectiveness. Effectiveness is the degree to
material (in our case, oral tissue).10 Depending on which the therapy provides clinical success in an the tissue, some lasers penetrate deeper than uncontrolled, real-world environment, and repre- others. By contrast, other laser wavelengths are sents the final verdict. It is not uncommon for limited to a shallow penetration and have a sur- products to pass the efficacy test and then fail in face effect on tissue. The deeper the laser energy the subsequent test of effectiveness in the field.
penetrates, the more it is scattered and dis- One should keep in mind that both efficacy and tributed throughout the tissue. The degree to effectiveness are required for the greatest confi- which this occurs also is affected by the power of the laser and exposure duration, but wavelength From an ethical standpoint, it is important to use the best available evidence when making clin- The depth of penetration that is characteristic ical decisions. Sometimes the best evidence comes of a wavelength is a critical feature that can influ- from meta-analyses or from the results of well- ence its utility for any particular application. For conducted clinical trials. Sometimes, however, no example, the CO2 laser penetrates only about 0.03 direct evidence is available to use. In such cases, to 0.1 millimeters into tissue. This provides just inferences sometimes can be made on the basis of enough depth to seal blood vessels, lymph vessels other credible data and biological principles. This and nerve endings measuring up to 0.5 mm in is part of good clinical judgment and constitutes a diameter. The clinical result of this penetration is significant aspect of what we do as clinicians. good hemostasis and minimal postoperative mor- The important principle here, however, is that bidity. By comparison, the Nd:YAG laser pene- we must do all we can to obtain the best and most trates 2 to 5 mm into tissue. While this deeper Copyright 2004 American Dental Association. All rights reserved.
exposure may be desirable for hemostasis in more into account when assessing the thermal risk to vascular tissue such as the liver or kidney, it has caused concern about the risk of collateraldamage in oral sites where bone and other hard WAVELENGTHS USED IN DENTISTRY
Several laser wavelengths are used in dentistry Continuous and pulsed waveform. Wave-
(Table11-31). In this section, we briefly discuss length works in concert with a feature called these wavelengths and the uses that are backed “waveform” to influence the actual tissue effect.
Laser energy can be delivered in two waveforms, CO2. CO2 lasers operate at a wavelength of
continuous and pulsed, which can result in dif- 10.6 µm. They can be operated in a gated wave- ferent tissue effects. Continuous-wave lasers can deliver large amounts of energy to the tissue in a CO2 lasers can be used for a number of soft- steady, uninterrupted stream, usually at low-to- tissue applications,32 including the following: moderate intensities. Methods of interrupting, or gating, this continuous-wave beam also exist.
This usually is done to deliver short, precisely timed, low-to-moderate–intensity exposures, either singly or in a train of exposures, with a cooling-off period in between. Pulsed lasers typi- dde-epithelialization of gingival tissue during cally deliver smaller amounts of energy to the periodontal regenerative procedures.
tissue in interrupted bursts, often at much higher The CO2 laser offers a number of advantages intensities than those with continuous or gated for such applications. It provides excellent hemostasis, offering the dentist a clear operating The optical properties of the tissue come into field and allowing for instant visual feedback. In play only with laser wavelengths that have low addition, the CO2 laser removes tissue efficiently absorption (or, conversely, high penetration) in and quickly and causes negligible concern about tissue. Transmission and scattering of energy to subsurface tissue damage, as the effect is on the deeper areas can take place only before ab- surface only.33 Postoperative pain usually is min- sorption occurs. Thus, they seldom occur with lasers whose energies are highly (or quickly) As with any piece of equipment, the CO2 laser also has some disadvantages. For example, Once the light from dental lasers is absorbed, it wound healing can be delayed for a few days.33 In is converted to heat. The thermal effects of this addition, there is a lack of tactile feedback, heat depend, in large part, on tissue composition because only the laser light (not a fiber tip) (that is, the amount of water and organic and impinges on the tissue. However, feedback to the inorganic components in the tissue) and the clinician is visual and typically excellent, because length of time the beam is focused on the target tissue. The duration of exposure results in tem- Dentists should be aware that CO2-treated perature increases that may cause the tissue to tissue will have a black/brown appearance, which change in structure and composition. These is caused by a carbon residue that will easily changes may range from denaturation to vapor- rinse off within the first few days after the pro- ization and carbonization, and even melting fol- cedure. The exposed area can go through color lowed by recrystallization in the case of hard changes for 10 to 14 days, eventually resulting in In addition to the heat generated by a laser Nd:YAG. The Nd:YAG laser operates at a
beam, dentists should be aware that heat can be wavelength of 1.064 µm in a high-intensity pulsed generated from the laser unit itself. For example, contact-tip pulsed Nd:YAG lasers deliver heat to Like the CO2 laser, the Nd:YAG laser can be the tissue from two sources: surface heat from used to perform a number of soft-tissue applica- the hot fiber tip and internal heat from the absorption that occurs after penetration and scattering of the light energy that passes beyond the fiber tip. Dentists must take both sources Copyright 2004 American Dental Association. All rights reserved.
Carbon Dioxide
de-epithelialization of gingiva during periodontal regenerative procedures Neodymium:Yttrium-
Soft-tissue incision and ablation*; incip- Aluminum-Garnet
enamel and dentin12; U.S. FDA† clearancefor use on cementum and bone; root canalpreparation13,14 Erbium, Chromium:
Enamel etching15-17; caries removal18,19; Yttrium-Selenium-
cavity preparation18-20; cutting bone in vitro Gallium-Garnet
with no burning, melting or alteration ofthe calcium:phosphorus ratio21,22;root canal preparation23 Curing resins24-30; soft-tissue incision and Holmium:Yttrium-
(or Diode)
* Including gingival troughing, esthetic contouring of gingiva, treatment of oral ulcers, frenectomy and gingivectomy.
† FDA: Food and Drug Administration.
‡ Extinction length in water: 1.0 µm (90 percent absorption depth).
point occurs (that is, the point at which the tissue In addition, the Nd:YAG laser can be used to begins to vaporize). To enhance the surface remove incipient enamel caries,35 although not as absorption of the energy (and shorten this lag efficiently as can the erbium:YAG, or Er:YAG, or time), some have recommended the topical appli- erbium, chromium:yttrium-selenium-gallium- cation of photoabsorbing black dyes to the tissue.36 Direct exposure of the pulp by Nd:YAG laser The Nd:YAG laser also offers good hemostasis light can occur when this wavelength of energy is during soft-tissue procedures, which facilitates a directed at either the crown or the root of the clear operating field. In addition, the Nd:YAG tooth. Pulpal damage (such as denaturation and laser offers a flexible fiber delivery system, disruption of the vascular and neuronal tissue) avoiding the need for cumbersome articulated- from this laser can occur, and is associated with a decrease in pulpal function (that is, sensi- The Nd:YAG laser has a number of disadvan- tivity).37,38 Although decreasing sensitivity may be tages, however. It has the greatest depth of pene- popular from the patient’s perspective, it is tration of all the available dental surgical laser important to realize that we do not know if this systems, which means that tissues under the sur- laser-induced pulpal damage will result in the face are exposed to laser energy. This is cause for need for endodontic therapy. One would expect concern because of the risk of unwanted collateral that a compromised vasculature would decrease damage, especially in the underlying bone or the pulpal life expectancy. Finally, wound healing in dental pulp, as well as the associated postopera- soft tissue can be delayed for a few days or more In addition, the diminished localization of the Er:YAG. The Er:YAG laser operates at a wave-
energy on the tissue’s surface makes vaporization length of 2.94 µm and in a pulsed waveform. The of soft tissue with an Nd:YAG laser slower than FDA has cleared it for use on cementum and with the better-absorbed laser wavelengths, such bone, and it has a variety of hard-tissue applica- as those produced by the CO2 laser. Tissue vapor- ization can require a lag time until the activation Copyright 2004 American Dental Association. All rights reserved.
dcavity preparation in both enamel and dentin12; involve the etching results. With this laser, enamel etching produces bonds with a wide range The Er:YAG laser has a number of advantages.
of strengths, which can be unreliable.53 To mini- It produces clean, sharp margins in enamel and mize leakage in resins, clinicians may need to dentin. In addition, pulpal safety is not a signifi- acid-etch enamel after preparing cavities with the cant concern,39 because the depth of energy pene- tration is negligible.40,41 One study42 suggested that pulps may respond even better to prepara- Er,Cr:YSGG laser include the fact that melting tions done with the Er:YAG laser than those done enamel with this laser increases resistance to with the bur. When the Er:YAG laser is used for acid demineralization.54 In addition, dentists caries removal, the patient usually does not should realize that changing the characteristics of require local anesthesia.43 The laser is antimicro- the air/water spray influences the tissue effect bial when used within root canals44 and on root surfaces,45 and it removes endotoxins from root Argon. The argon laser operates at a wave-
surfaces.46 Finally, vibration from the Er:YAG length of 457 to 502 nanometers, using a pulsed Argon lasers do not
necessarily produce a
resin with physical
properties superior to
those of resins cured
with traditional
halogen curing lights.
length that is absorbed by hemoglobin, which pro- Er,Cr:YSGG. The Er,Cr:YSGG operates at a
wavelength of 2.78 µm, with an extinction length Dentists should be aware that, when used for in water of 1.0 µm (a measure that translates into resin curing, argon lasers do not necessarily pro- a depth of 90 percent absorption). The waveform duce a resin with physical properties superior to those of resins cured with traditional halogen The Er,Cr:YSGG laser has several hard-tissue curing lights.58,59 In addition, some resins contain multiple initiators that activate at different wave- lengths. This suggests that the relatively narrow spectrum of a laser might not be the best din vitro bone cutting with no burning, melting Holmium:yttrium-aluminum-garnet, or
or alteration of the calcium:phosphorus ratio21,22; Ho:YAG. The Ho:YAG laser operates at a wave-
length of 2.1 µm, and uses a pulsed waveform. The Er,Cr:YSGG laser has a number of advan- This laser is used for soft-tissue incision and tages. Multiple uses for the Er,Cr:YSGG laser ablation procedures, including the following: make the economics of providing laser therapy more feasible. The laser produces a rough surface cracking. In dentin, no smear layer remains, which suggests good results with bonding.16 The The advantages of the Ho:YAG laser center on Er,Cr:YSGG laser is safe for the pulp.51,52 When its surface effect on tissue. The Ho:YAG laser is using the Er,Cr:YSGG laser, the dentist often less penetrating than the Nd:YAG laser and, does not need to administer local anesthetic for therefore, is faster than the Nd:YAG at cutting caries removal and cavity preparation.
The disadvantages of the Er,Cr:YSGG laser Although the Ho:YAG laser is bactericidal,62 it Copyright 2004 American Dental Association. All rights reserved.
should not be used to decontaminate implants tium, laser curettage appears to be neither scien- because it damages the implant surface.63 Gallium-arsenide (or diode). The diode laser
operates at a wavelength of 904 nm, and uses apulsed or continuous waveform.
In October 1998, the ADA Council on Scientific The diode laser has proven to be successful Affairs reviewed laser-assisted bleaching 70 The with soft-tissue incision and ablation. This laser council concluded that because of concerns regarding pulpal safety and a lack of controlled clinical studies, the CO2 laser could not be recom- mended for tooth-whitening applications. The council indicated, however, that the argon laser might be an acceptable replacement for the con- We should point out that the diode laser does ventional curing light if the manufacturer’s sug- not affect the inflammatory function of monocytes gested procedures are followed carefully.
or endothelial cells, or the adhesion of endothelial According to an ADA survey,2 about 3.3 percent cells.64 In addition, it can kill some microbes in the of dentists who have lasers use them for acti- presence of a photosensitizer,65 as well as some vating bleaching solutions for tooth-whitening Laser curettage
appears to be neither
scientifically nor
ethically justified.
mention. Both the Nd:YAG and gallium-arsenide methods of caries detection in occlusal fis- (or diode) lasers are promoted for curettage. A sures.71-74 However, some have voiced concern that critical review of the best available evidence, how- while laser fluorescence has demonstrated good ever, strongly indicates that there is no added sensitivity and excellent reproducibility, it is not benefit to the patient when this procedure is per- able to quantify the extent of decay.72 Laser fluo- formed after traditional mechanical scaling and rescence also has performed well in the detection root planing.68 Furthermore, the American of residual caries.75 While safety is not a concern Academy of Periodontology recently issued a with this low-power laser application, more data statement that curettage adds no benefit as an are required to aid in the clinical interpretation of adjunctive procedure, regardless of how it is per- the results and to develop a clinically useful sense formed (that is, mechanically, chemically or with laser energy), and that the profession as a whole DISCUSSION
considers curettage to have no clinical value.69 Proponents of laser curettage point to the With the exception of laser fluorescence for caries ability of these lasers to kill microorganisms.
detection, little evidence exists to support the Although the data indicate that this effect is pos- notion that lasers currently produce superior sible albeit inconsistent, it has not been corre- results to those for procedures that have been lated with an improvement in periodontal attach- cleared by the FDA. Some features of laser use, however, are attractive with regard to patient effectiveness of a periodontal therapy such as root appeal. For example, postoperative healing after planing is its effect on the attachment level.
soft-tissue surgery with the CO2 laser typically Other adjunctive therapies, such as local drug involves much less morbidity than that after tra- delivery or subantimicrobial-dose doxycycline, ditional scalpel surgery. It is interesting that have been shown to improve the attachment some early evidence suggests that Er:YAG laser level. Curettage, with or without a laser, has not.
energy can produce superior attachment levels With no demonstrable benefit and with a sig- after root débridement compared with mechanical nificant risk of collateral damage to the periodon- root planing.48 Such novel techniques, while Copyright 2004 American Dental Association. All rights reserved.
requiring further development and testing, hold and cup forceps stripping. Otolaryngol Head Neck Surg 1986;95(3 part1):273-7.
4. Callahan DJ. Osseous healing after CO2 laser osteotomy. Foot What is perhaps the most important recent 5. Friesen LR, Cobb CM, Rapley JW, Forgas-Brockman L, Spencer P.
development in laser dentistry is the advent of Laser irradiation of bone, part II: healing response following treatment the Er,Cr:YSGG laser, which is used with a water by CO2 and Nd:YAG lasers. J Periodontol 1999;70(1):75-83.
6. Park GC, Wiseman JB, Hayes DK. The evaluation of rhytidectomy spray. This laser is capable of multiple applica- flap healing after CO2 laser resurfacing in a pig model. Otolaryngol tions because its interaction with tissue is 7. U.S. Food and Drug Administration, Center for Devices and Radio- strongly influenced by variations in the air-to- logical Health. Premarket notification [510(k)]. Available at: water ratio of the spray. It can be used on soft “”. Accessed Aug. 21, 2003.
8. Stanley HR. Design for a human pulp study, part I. Oral Surg Oral tissue, enamel, dentin and bone, and its shallow interaction minimizes the risk of collateral 9. Stanley HR. Design for a human pulp study, part II. Oral Surg Oral Med Oral Pathol 1968;25:756-64.
damage. Also, the ability to be used for multiple 10. Dederich DN. Laser/tissue interaction: what happens to laser applications improves the economic feasibility of light when it strikes tissue? JADA 1993;124(2):57-61.
11. Pelagalli J, Gimbel CB, Hansen RT, Swett A, Winn DW 2nd.
this laser. Another significant benefit of this laser Investigational study of the use of Er:YAG laser versus dental drill for is that it does not necessitate the use of local caries removal and cavity preparation: phase I. J Clin Laser Med Surg1997;15(3):109-15.
anesthestic in many operative procedures. 12. Keller U, Hibst R. Effects of Er:YAG laser in caries treatment: a However, traditional methods of performing clinical pilot study. Lasers Surg Med 1997;20(1):32-8.
13. Takeda FH, Harashima T, Kimura Y, Matsumoto K. Efficacy of the same procedures still are more economical on Er:YAG laser irradiation in removing debris and smear layer on root a per-patient basis. Recent innovations to canal walls. J Endod 1998;24:548-51.
14. Kimura Y, Yonaga K, Yokoyama K, Matsuoka E, Sakai K, improve patient appeal and the multiple-use Matsumoto K. Apical leakage of obturated canals prepared by Er:YAG capability while achieving equivalent results 15. Gutknecht N, Apel C, Schafer C, Lampert F. Microleakage of com- posite fillings in Er,Cr:YSGG laser-prepared Class II cavities. Lasers 16. Hossain M, Nakamura Y, Yamada Y, et al. Analysis of surface roughness of enamel and dentin after Er,Cr:YSGG laser irradiation. J CONCLUSION
Clin Laser Med Surg 2001;19:297-303.
17. Hossain M, Nakamura Y, Yamada Y, Murakami Y, Matsumoto K.
The development of novel techniques to produce Microleakage of composite resin restoration in cavities prepared by results that are superior to those of traditional Er,Cr:YSGG laser irradiation and etched bur cavities in primary teeth.
J Clin Pediatr Dent 2002;26:263-8.
methods, or to produce results not possible at all 18. Hadley J, Young DA, Eversole LR, Gornbein JA. A laser-powered by current methods, would improve the case for hydrokinetic system for caries removal and cavity preparation. JADA2000;131:777-85.
use of lasers in dentistry. However, until the laser 19. Hossain M, Nakamura Y, Yamada Y, Murakami Y, Matsumoto K.
is shown scientifically to bring about results that Compositional and structural changes of human dentin following cariesremoval by Er,Cr:YSGG laser irradiation in primary teeth. J Clin are superior to those achieved with conventional means for a significant number of applications, 20. Matsumoto K, Hossain M, Hossain MM, Kawano H, Kimura Y.
Clinical assessment of Er,Cr:YSGG laser application for cavity prepa- dentists who choose not to use lasers should not ration. J Clin Laser Med Surg 2002;20(1):17-21.
consider themselves to be lesser practitioners for 21. Wang X, Ishizaki NT, Suzuki N, Kimura Y, Matsumoto K. Morphological changes of bovine mandibular bone irradiated by Er,Cr:YSGG laser: an in vitro study. J Clin Laser Med Surg2002;20:245-50.
Dr. Dederich is a member of the ADA Council on Scientific Affairs 22. Kimura Y, Yu DG, Fujita A, Yamashita A, Murakami Y, and is head, Department of Periodontics, Louisiana State University Matsumoto K. Effects of erbium,chromium:YSGG laser irradiation on School of Dentistry, 1100 Florida Ave., Box 138, New Orleans, La.
canine mandibular bone. J Periodontol 2001;72:1178-82.
70119-2799, e-mail “[email protected]”. Address reprint requests to 23. Yamazaki R, Goya C, Yu DG, Kimura Y, Matsumoto K. Effects of erbium,chromium:YSGG laser irradiation on root canal walls: a scan-ning electron microscopic and thermographic study. J Endod Dr. Bushick is second vice president of the American Dental Associa- tion. At the time this article was written, Dr. Bushick was a member of 24. Hinoura K, Miyazaki M, Onose H. Influence of argon laser curing the ADA Council on Scientific Affairs. He is in private practice in on resin bond strength. Am J Dent 1993;6(2):69-71.
25. Shanthala BM, Munshi AK. Laser vs. visible-light cured com- Although Practical Science is developed in cooperation with the ADA posite resin: an in vitro shear bond study. J Clin Pediatr Dent 1995; Council on Scientific Affairs and the Division of Science, the opinions expressed in this article are those of the authors and do not necessarily 26. Powell GL, Anderson JR, Blankenau RJ. Laser and curing light reflect the views and positions of the Council, the Division or the induced in vitro pulpal temperature changes. J Clin Laser Med Surg 27. Cobb DS, Dederich DN, Gardner TV. In vitro temperature change 1. American Dental Association, Survey Center. Survey of consumer at the dentin/pulpal interface by using conventional visible light versus attitudes and behaviors regarding dental issues. Chicago: American argon laser. Lasers Surg Med 2000;26:386-97.
28. Lalani N, Foley TF, Voth R, Banting D, Mamandras A. Polymer- 2. American Dental Association, Survey Center. The 2000 survey of ization with the argon laser: curing time and shear bond strength.
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29. Talbot TQ, Blankenau RJ, Zobitz ME, Weaver AL, Lohse CM, 3. Durkin GE, Duncavage JA, Toohill RJ, Tieu TM, Caya JG. Wound Rebellato J. Effect of argon laser irradiation on shear bond strength of healing of true vocal cord squamous epithelium after CO2 laser ablation orthodontic brackets: an in vitro study. Am J Orthod Dentofacial Copyright 2004 American Dental Association. All rights reserved.
52. Rizoiu I, Kohanghadosh F, Kimmel AI, Eversole LR. Pulpal 30. St-Georges AJ, Swift EJ Jr, Thompson JY, Heymann HO. Curing thermal responses to an erbium,chromium: YSGG pulsed laser light intensity effects on wear resistance of two resin composites. Oper hydrokinetic system. Oral Surg Oral Med Oral Pathol Oral Radiol 31. Baik JW, Rueggeberg FA, Liewehr FR. Effect of light-enhanced 53. Usumez S, Orhan M, Usumez A. Laser etching of enamel for bleaching on in vitro surface and intrapulpal temperature rise. J direct bonding with an Er,Cr:YSGG hydrokinetic laser system. Am J Orthod Dentofacial Orthop 2002;122:649-56.
32. Research, Science and Therapy Committee of the American 54. Hossain M, Kimura Y, Nakamura Y, Yamada Y, Kinoshita JI, Academy of Periodontology. Lasers in periodontics. J Periodontol Matsumoto K. A study on acquired acid resistance of enamel and dentin irradiated by Er,Cr:YSGG laser. J Clin Laser Med Surg 33. Fisher SE, Frame JW, Browne RM, Tranter RM. A comparative histological study of wound healing following CO2 laser and conven- 55. Hossain M, Nakamura Y, Yamada Y, Kimura Y, Matsumoto N, tional surgical excision of canine buccal mucosa. Arch Oral Biol Matsumoto K. Effects of Er,Cr:YSGG laser irradiation in human enamel and dentin: ablation and morphological studies. J Clin Laser 34. Pick RM, Colvard MD. Current status of lasers in soft tissue dental surgery. J Periodontol 1993;64:589-602.
56. Passes H, Furman M, Rosenfeld D, Jurim A. A case study of 35. White JM, Goodis HE, Setcos JC, Eakle S, Hulscher BE, Rose CL.
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36. Jennett E, Motamedi M, Rastegar S, Frederickson C, Arcoria C, 58. Puppala R, Hegde A, Munshi AK. Laser and light cured composite Powers JM. Dye-enhanced ablation of enamel by pulsed lasers. J Dent resin restorations: in-vitro comparison of isotope and dye penetrations.
37. Tokita Y, Sunakawa M, Suda H. Pulsed Nd:YAG laser irradiation 59. Fleming MG, Maillet WA. Photopolymerization of composite resin of the tooth pulp in the cat, part I: effect of spot lasing. Lasers Surg using the argon laser. J Can Dent Assoc 1999;65:447-50.
60. Blankenau R, Erickson RL, Rueggeberg F. New light curing 38. Sunakawa M, Tokita Y, Suda H. Pulsed Nd:YAG laser irradiation options for composite resin restorations. Compend Contin Educ Dent of the tooth pulp in the cat, part II: effect of scanning lasing. Lasers 61. Brenner M, Wong H, Yoong B, et al. Comparison of Ho:YAG 39. Nair PN, Baltensperger MM, Luder HU, Eyrich GK. Pulpal versus Nd:YAG thoracoscopic laser treatment of pulmonary bullae in a response to Er:YAG laser drilling of dentine in healthy human third rabbit model. J Clin Laser Med Surg 1997;15(3):103-8.
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Mayo Medical Laboratories Test Catalog [Previous Drugs Detectable by Drug Screen This test specifically screens for each of the drugs listed below. Results for drugs indicated by # are quantitative in plasma, all others are qualitative. All results are qualitative in urine and gastric fluid. Plasma (and Gastric) Analgesics: Acetaminophen (Tylenol )# Acetylsalicylate


BCMP 207: Study Questions for Discussion of February 24, 2000 The two papers for this discussion take genetic approaches. The first paper uses amodel organism, C. elegans, to examine potential targets for a famous, but poorly understooddrug, fluoxetine (a.k.a Prozac). Aside from raising the question -- Do worms get depressed? --it illustrates this approach and its potential advantages and disa

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