P R A C T I C A L A B S T R A C T Background. During the last two decades, much has been written in both the scientific litera- Lasers in dentistry DOUGLAS N. DEDERICH, B.S.E.E., D.D.S., M.Sc., Ph.D.; RONALD D. BUSHICK, D.M.D., Ph.D., M.S.
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 BACKGROUND 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. P R A C T I C A L
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 practices.
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. P R A C T I C A L
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. LASER-INDUCED INTERACTION BETWEEN LIGHT AND TISSUE SAFETY, EFFICACY AND EFFECTIVENESS
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. P R A C T I C A L
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. P R A C T I C A L CHARACTERISTICS OF LASERS USED IN DENTISTRY. LASER TYPE WAVELENGTH WAVEFORM APPLICATIONS Carbon Dioxide
de-epithelialization of gingiva during periodontal regenerative procedures
Neodymium:Yttrium-
Soft-tissue incision and ablation*; incip-
Aluminum-Garnet Erbium:Yttrium- 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- Aluminum-Garnet Gallium-Arsenide (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. P R A C T I C A L
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. P R A C T I C A L
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 LASER BLEACHING
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. LASER CURETTAGE LASER CARIES DETECTION
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. P R A C T I C A L
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
“www.fda.gov/cdrh/devadvice/314.html”. 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
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Copyright 2004 American Dental Association. All rights reserved.
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