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In Vitro Study of the Soft Tissue Effects of Microsecond-Pulsed CO2 Laser Parameters During Soft Tissue Incision and Sulcular Debridement

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In Vitro Study of the Soft Tissue Effects of Microsecond-Pulsed CO2 Laser Parameters During Soft Tissue Incision and Sulcular Debridement

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Carbon dioxide (CO(2)) lasers are an important part of dental treatment. Advances in laser technology have produced microsecond pulse durations and small beam sizes. The histological effects of porcine intraoral soft tissue with a range of microsecond-pulsed CO(2) laser parameters used for incision and sulcular debridement were evaluated in vitro and compared with historical histologic data. Fresh pig mandibles were used to perform incision and sulcular debridement using a microsecond-pulsed CO(2) laser. lambda = 10,600 nm, articulated arm delivered non-contact with spot size 200 microm, 500 microm, and 1 mm, and focal distance of 1 mm. For sulcular debridement, epithelium within periodontal pocket (6 mm x 6 mm) was removed. Laser parameters for incision were from 30 Hz, 350 microseconds, 28 mJ and energy density of 143 J/cm(2) to 90 Hz, 1,000 microseconds, 60 mJ, and 1,911 J/cm(2). Width and depth of tissue removed, as well as coagulation effects of the tissue treated were measured. These were compared to historical histologic database. Laser-treated surfaces were observed qualitatively using scanning electron microscopy (SEM). All laser parameters studied were able to reach the defined simulation objectives in reasonable amounts of time, less than a minute for incision and <20 seconds for sulcular debridement. The depth of the cut was significantly greater than the historical 95% confidence interval, but equivalent for width, lateral, and deep coagulation to the historical database. Sulcular debridement was achieved with minimal coagulation, <100 microm. SEM analysis did not identify any alteration to enamel, dentin, or bone during sulcular debridement. The treatment objectives of incision and sulcular debridement were achieved with minimal lateral and deep coagulation in reasonable amount of time. Microsecond-pulsed CO(2) lasers can be safely and effectively used for incision and sulcular debridement.
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Lasers in Surgery and Medicine 42:257–263 (2010)
In Vitro Study of the Soft Tissue Effects of
Microsecond-Pulsed CO
2
Laser Parameters During
Soft Tissue Incision and Sulcular Debridement
Ram M. Vaderhobli, DDS,MS,* Joel M. White, DDS,MS, Christine Le, BS, Sunita Ho, PhD,
and Richard Jordan, DDS,PhD
Department of Preventive and Restorative Dental Sciences, Department of Oral Facial Sciences,
University of California San Francisco (UCSF), San Francisco, California 94143
Background and Objectives: Carbon dioxide (CO
2
)
lasers are an important part of dental treatment. Advances
in laser technology have produced microsecond pulse
durations and small beam sizes. The histological effects of
porcine intraoral soft tissue with a range of microsecond-
pulsed CO
2
laser parameters used for incision and sulcular
debridement were evaluated in vitro and compared with
historical histologic data.
Study Design/Materials and Methods: Fresh pig
mandibles were used to perform incision and sulcular
debridement using a microsecond-pulsed CO
2
laser.
l¼10,600 nm, articulated arm delivered non-contact with
spot size 200 mm, 500 mm, and 1 mm, and focal distance of
1 mm. For sulcular debridement, epithelium within perio-
dontal pocket (6 mm6 mm) was removed. Laser parame-
ters for incision were from 30 Hz, 350 microseconds, 28 mJ
and energy density of 143 J/cm
2
to 90 Hz, 1,000 micro-
seconds, 60 mJ, and 1,911 J/cm
2
. Width and depth of tissue
removed, as well as coagulation effects of the tissue treated
were measured. These were compared to historical histo-
logic database. Laser-treated surfaces were observed
qualitatively using scanning electron microscopy (SEM).
Results: All laser parameters studied were able to reach
the defined simulation objectives in reasonable amounts
of time, less than a minute for incision and <20 seconds for
sulcular debridement. The depth of the cut was signifi-
cantly greater than the historical 95% confidence interval,
but equivalent for width, lateral, and deep coagulation to
the historical database. Sulcular debridement was
achieved with minimal coagulation, <100 mm. SEM anal-
ysis did not identify any alteration to enamel, dentin, or
bone during sulcular debridement.
Conclusion: The treatment objectives of incision and
sulcular debridement were achieved with minimal lateral
and deep coagulation in reasonable amount of time. Micro-
second-pulsed CO
2
lasers can be safely and effectively used
for incision and sulcular debridement. Lasers Surg. Med.
42:257– 263, 2010. ß2010 Wiley-Liss, Inc.
Key words: dentistry; laser; in vitro; incision; debride-
ment
INTRODUCTION
Since the development of the first laser in the 1960s,
dental researchers have investigated the effects of laser
radiation on teeth, bone, pulp, and oral mucosal tissues [1].
Many authors have reported the use of carbon dioxide (CO
2
)
lasers for soft tissue applications in dentistry [2,3]. The
Food and Drug Administration (FDA) granted clearance for
marketing CO
2
lasers for soft tissue procedures such as
frenectomy, gingivectomy, biopsies, and removal of benign
and malignant lesions. Specific indications for use in
dentistry include apthous ulcer treatment, coagulation of
extraction sites, sulcular debridement, and intraoral soft
tissue surgeries such as ablating, incising, and excising
(U.S. FDA 510(k) marketing clearance). The original CO
2
lasers were continuous wave or interrupted pulse durations
of about 0.5 seconds to 50 milliseconds with non-contact
delivery and large beam diameters up to 1 mm and larger.
Previous studies with these continuous wave CO
2
lasers
showed a variety of structural and ultrasonic changes of the
hard tooth structure. These included cracking, flaking,
crater formation, charring, melting, and recrystallizaton
due to the highly efficient absorption of CO
2
wavelengths by
the apatite mineral of hard tissues [48]. The thermal
effects of these CO
2
lasers at various parameters have also
been studied extensively [9,10]. These studies indicated
that application of CO
2
laser created unacceptable thermal
damage to adjacent tissue. Because of these reasons early
CO
2
laser system had been limited by their continuous
wave operations and delivery system constraints.
With new technologies, dental laser manufacturers
now claim to have shorter pulse durations (as short as
150-microsecond pulse duration) with beam diameters of
as small as 100 mm. These lasers are now marketed for soft
tissue intraoral procedures as described earlier. The
advantages compared to scalpel wounds include relatively
bloodless surgery with little if any bleeding post-surgery;
site-specific wound sterilization; minimal swelling and
scarring; reduced necessity for suturing; decreased inci-
dence of mechanical trauma; shorter operative time;
Contract grant sponsor: Great Planes Technology, Inc. (GPT,
Fairfield, Nebraska).
*Correspondence to: Ram M. Vaderhobli, DDS, MS, Health
Sciences Assistant Professor, Department of Preventive and
Restorative Dental Sciences, Box# 0758, 707 Parnassus Avenue,
San Francisco, CA 94143. E-mail: ram.vaderhobli@ucsf.edu
Accepted 18 November 2009
Published online 23 March 2010 in Wiley InterScience
(www.interscience.wiley.com).
DOI 10.1002/lsm.20888
ß2010 Wiley-Liss, Inc.
favorable patient acceptance; decreased use of local
anesthesia; and little or no post-operative pain [11,12].
However, little work has been done to study the cutting and
coagulation efficiency of these microsecond pulse CO
2
lasers.
Previous studies determined the boundaries of the 95%
confidence limits for the time of procedure, length, width,
lateral coagulation, and deep coagulation [12]. Due to the
potential for accidental contact with adjacent hard tissue it
also becomes necessary for us to understand the interaction
of lasers with dental hard tissues. The purpose of this study
was to investigate the newer microsecond pulse duration
and smaller diameter delivery system to determine the
histologic effects of CO
2
laser used for: cutting and
coagulation (incision and sulcular debridement) of oral
porcine soft tissue at various power and frequency settings,
in relation to histological histologic databases.
MATERIALS AND METHODS
A microsecond-pulsed CO
2
dental laser (Spectra-
Denta
TM
, Lutronics, Great Planes Technology, Inc., Fair-
field, Nebraska) with a wavelength of 10,600 nm and an
articulated arm non-contact delivery mode was used. Pulse
profile was measured at room temperature using an
HgCdZnTc detector (Boston Electronics, Boston, MA).
The laser tips utilized were micro-0.1, cone-0.2, 0.5, and
1 mm. The defined laser parameters (incision, and sulcular
debridement settings, historical data) functioned as inde-
pendent variables. Dependent variables included histolog-
ical assessment of incision width, depth, lateral and deep
coagulation, adverse events (qualitative assessments), and
accidental exposure to adjacent tissues. Experiments were
conducted on porcine tongue and gingiva that was acquired
within 24 hours of animal sacrifice, from a local slaughter
house through permit of the United States Department of
Agriculture. The tissue specimens were stored during
transit at 48C and 100% humidity to prevent tissue
degradation. Specimens were allowed to return to room
temperature before experiments were conducted. Fifteen
millimeters incisions were performed on the porcine tongue
by an experienced operator at the rate of 2.5 mm per second
and a force of 24 9 g of pressure. One excision 15 mm
excision for each laser parameter was conducted. The
treatment objective was to cut through the epithelium to
the basement membrane. The range of laser parameters is
shown in Table 1.
Following incision, the tissue specimens were bio-
prepared for histologic examination to determine
cutting and degree of histologic coagulation, fixed in
formalin, sectioned at 5 mm, and stained with hemotoxylin
and eosin. The sections were taken from the middle of the
cutting zone to ensure that each specimen represented the
characteristics of that incision. Light microscopy and a
measuring microscope (Olympus BX51), using the 10
objective was used to determine the depth and width of
tissue removed as well as the lateral and deep coagulation
effects at the borders of the incision. Multiple sections of
the most characteristic zone of each tissue specimen were
measured, with a minimum of three measurements made
for each set of specific laser parameters. Measurements
were then compared to the histologic historical database
[13].
Using a 3
4universal scaler, the periodontal pockets were
scaled to remove any calculus or foreign particles that
would interfere with sulcular debridement. Sulcular
debridement was then performed on porcine gingiva at five
different laser parameters. The objective was the removal
of the epithelium within the periodontal pocket
(6 mm6 mm) using the same microsecond-pulsed CO
2
laser. Three sulcular debridement procedures were con-
ducted for each laser parameter. The laser parameters for
sulcular debridement are shown in Table 1.
Direct Intentional exposure to the tooth was made during
the incision of porcine oral mucosa. Also, exposure to
adjacent hard tissue during sulcular debridement was
evaluated for the presence of laser tissue interaction.
Scanning electron microscopy (SEM) was utilized with
a charge free anticontamination system, CFAS. Samples
were imaged from 10 to 500magnifications. Qualitia-
tive assessments were made. If there was a visual or
microscopic interaction, then an assessment of ‘‘mild,’’
‘‘moderate,’’ or ‘‘severe’’ during accidental exposure, assess-
ment was made.
Statistical analysis was performed using a multifactorial
randomized analysis of variance (P0.05) for parametric
data of histologic measurements and time. Data were
TABLE 1. Incision Laser Parameters for Selected Tip Types (0.5, 1.0, Cone, and Micro) With Time Taken and
Average Power Output
Tip size
0.5 mm 1.0 mm Cone 0.2 mm Micro 0.1 mm
Time Avg. width Time Avg. width Time Avg. width Time Avg. width
30 Hz/350 microseconds (28 mJ)
a
0.55 0.202 0.55 0.44 1.04 0.61 0.54 0.42
50 Hz/500 microseconds (28 mJ)
a
0.56 0.637 0.53 0.97 0.50 1.34 0.56 0.85
70 Hz/700 microseconds (28 mJ)
a
0.53 0.908 0.50 1.53 0.47 2.13 0.56 1.71
90 Hz/1,000 microseconds (28 mJ) 0.32 1.39 1.11 2.66 0.53 3.54 0.55 2.39
3 W 0.59 1.16 1.03 1.96 1.04 3 0.58 1.78
a
Laser parameters for sulcular debridement.
258 VADERHOBLI ET AL.
compared with the existing extensive histologic database
for lasers, using the established confidence intervals set at
95% so that trends outside this range could be identified.
RESULTS
Pulse Profile
The measured pulse duration confirmed that the pulses
were in the microsecond regime as shown in Figure 1. Pulse
durations were found to be between 40 and 200 micro-
seconds. The range of calculated energy densities studied
for excision were from 36 to 1,911 J/cm
2
and for sulcular
debridement were 143 –270 J/cm
2
, although due to energy
loss at the tip, the actual energy density may be much lower
than the calculated energy density (of similar proportion as
the power loss from the smaller tips).
Histologic Evaluation
Examination of the laser incisions revealed the length
and width of the cut as well as both lateral and deep thermal
coagulation histologically. Figure 2 is a representative
histologic section of porcine tongue after incision with CO
2
laser at 50 Hz/500 microseconds and 1.34 W with a 0.2 mm
cone tip. Epithelium was removed to the basement
membrane; width and depth of cut are easily identified as
are the lateral coagulation and deep coagulation, shown in
Figure 2. The surrounding area adjacent to the cut and
coagulation was histologically normal.
Cutting Efficiency
The length of cuts with the CO
2
laser was significantly
deeper than the historical database and deeper than the
treatment objective (incision through the epithelium to the
basement membrane, about 1 mm) as represented by
Figure 3a. The data points were beyond the upper limit of
the 95% confidence interval. However, the width of the cuts,
lateral coagulation, and deep coagulation were similar to
the historical data and fell within the 95% confidence
intervals as depicted in Figures 3b and 4a,b. The duration of
cuts ranged from 30 seconds to around 2 minutes and was
within the 95% confidence intervals, Figure 5 and Table 1.
Lateral and deep coagulation ranged from 0.2 to 1.2 mm for
all tips. In all cases soft tissue excision began between 0.2
and 1 W. The time taken to make an incision was less than
a minute.
Sulcular Debridement
Sulcular epithelium was removed with minimal coagu-
lation <200 mm as shown in Figure 6 for 0.2 –0.6 W. Figure 7
is a representative section of the specimen prepared for
sulcular debridement histological measurements. No coag-
ulation of the epithelium was observed at 0.1 W. Coagu-
lation increased when power was increased to 1 W. Hand
scalers caused characteristic surface scratches, Figure 8a.
Hard tissue examination of the tooth revealed no visible
alteration to the tooth or to the root attachment at any of the
tested settings as shown in Figure 8b.
Hard Tissue Examination
Direct exposure to dentin and bone at powers >1W
caused visible change revealing bone and dentin ablation.
SEM analysis on these surfaces revealed characteristic
laser melting as shown in Figure 8c.
DISCUSSION
This study determined the safety and effectiveness of a
microsecond-pulsed CO
2
laser. The study confirmed the
microsecond pulse duration and small spot size of this new
laser device and delivery system and determined its
histological effects in an in vitro model. The histological
method used in this study is commonly used for measuring
immediate histologic cutting and coagulation of oral
tissues. The 10.6 mm microsecond-pulsed CO
2
laser tested
yielded comparable results. The histologic model utilized,
Fig. 1. Pulse profile depicting the pulse duration in the
microsecond regime. [Figure can be viewed in color online via
www.interscience.wiley.com.]
Fig. 2. Measurement sites for histologic evaluation: W, width
of incision; D, incision depth; LC, lateral coagulation; DC, deep
coagulation. [Figure can be viewed in color online via
www.interscience.wiley.com.]
MICROSECOND-PULSED CO
2
LASER PARAMETERS 259
tongue, and gingival tissues in vitro, are the standard for
testing the cutting efficiency of dental lasers. Histologic
measurements are widely used to measure the coagulation
effects [12]. Wilder Smith et al. [14] used the same model as
was utilized in the present study, and determined the
histological and incisional effects using a continuous wave
9.3 and 10.6 mmCO
2
laser in soft tissues. These tests
confirm in an in vitro model, that the laser parameters used
reach the treatment objective and result in acceptable
levels of coagulation. The treatment objective as defined
by years of laser research is the incision of the epithelium
through to the basement membrane. The applied science
approach undertaken in this study defines specific laser
parameters that result in specific tissue changes, which
include both lateral and deep coagulation.
In this study, the aims were to characterizing the specific
effects of various powers, frequencies on soft tissue
excision, sulcular debridement and hard tissue effects in
order to apply the newer microsecond pulse CO
2
laser
technology in the safest, most efficient manner. As the
pulse duration increases, so does the interaction times and
coagulation effects. This study found that the depths of
incision for these laser parameters and delivery system
were deeper than historical data. This could have impor-
tant clinical ramifications, as in the oral cavity, oral
mucosa, and gingival can be <1 mm in thickness. Based
on the depth of cut data reported here, clinicians are
encouraged to use the minimum parameters which reach
Fig. 4. a: The lateral coagulation were the same as our
historical data. b: Deep coagulation of cuts were the same as
historical data.
Fig. 3. a: Length of cuts were significantly deeper than
historical data. b: Width of cuts was same as our historical
data and mostly fell within the 95% confidence intervals.
260 VADERHOBLI ET AL.
the treatment objective and to carefully observe the tissue
being removed so as not to perforate thin, delicate oral
tissues.
In this controlled laboratory model, laser incisions were
done to manually simulate the clinical settings. Using an in
vitro model, either with porcine or bovine tissues, has its
own advantages in being able to evaluate many laser
parameters including high power, which would not be
utilized in vivo. Using a 15 mm incision provides sufficient
variability and samples for histologic analysis. Because
these lasers are very accurate in the production of laser
energy, there is little need to do multiple repetitions, as a
single incision is sufficient to obtain a large number of
histologic sections. Multiple incisions of the same param-
eters do not provide any additional information, and are
costly and time consuming to conduct the histologic
examination. Therefore, one 15 mm incision was used
and then sampled this incision multiple times for histologic
analysis. For the sulcular debridement technique a
6mm6 mm area was exposed within the periodontal
sulcus, with three repetitions per laser parameter. This
provided three individual tissue specimens for each laser
parameter, which was then sampled multiple times for
histologic analysis. Similarly, the entire root surface
adjacent to the sulcular debridement laser-treated site
was inspected. This experimental technique provides a
large amount of tissue specimens for multiple sectioning
and histologic analysis and a large area of root surface for
inspection.
The zone of coagulation adjacent to the laser incision was
kept to a minimum and compared well to historical
histological data. This signifies good wound healing
capabilities clinically with minimum damage to the vitality
of underlying tooth structures such as periodontium and
pulp. Depth of incision, although larger than historical
data, correlated well with average power. During incision,
the width of cut, lateral and deep coagulation, all correlated
with historical data.
This study also investigated the use of this device for
sulcular debridement. This technique is advocated in
conjunction with conventional scaling and root planning
for treatment of periodontal disease. This investigation
found that epithelium is removed within the periodontal
sulcus with minimal coagulation in a reasonable amount
of time. It is generally understood that complete epithelium
removal is a critical factor in obtaining a connective tissue
attachment during healing. Epithelium remaining within
the periodontal sulcus proliferates faster than connective
tissue and results in a weaker long junctional epithelial
attachment. There is a significant concern raised regarding
the use of lasers within the periodontal sulcus. The primary
concerns are either too extensive coagulation, with necrosis
of soft tissue, or accidental exposure and damage to the
Fig. 7. Representative histologic specimen for sulcular
debridement with measurements of coagulation. [Figure can
be viewed in color online via www.interscience.wiley.com.]
Fig. 6. For sulcular debridement the minimal coagulation was
<200 mm. [Figure can be viewed in color online via www.inter-
science.wiley.com.]
Fig. 5. Duration of cuts were within the 95% confidence
interval.
MICROSECOND-PULSED CO
2
LASER PARAMETERS 261
cementum, dentin or bone of the tooth, and periodontium.
The results found with these CO
2
laser parameters are
within the range of reported coagulation from fiberoptic
delivered Nd:YAG, diode, Er:YAG, and Er,Cr:YSGG lasers,
as demonstrated by the 95% confidence intervals reported
from historical data. For the sulcular debridement portion
of the study, it was confirmed that epithelium was removed
without detrimental effects to adjacent tissues, which has
been shown with Nd:YAG, diode, Er:YAG, and Er,Cr:YSGG
lasers. Nothing specific was done to limit or control the
thermal side effects of CO
2
laser parameters studied. The
device used has a low volume air flow at the tip, primarily to
keep ablation products from entering and clogging the tip.
There was no air or water spray used, and the tissue
specimens were irradiated in a moist condition, not wet and
not with a water stream or immersed in a water bath. This
study demonstrated in an in vitro model, epithelium
removal, with minimal coagulation and no evidence of
alteration of the cementum, dentin, or bone. This was due
primarily because the beam was aimed at the soft tissue to
be removed, away from the hard tissues, and the technique
utilized was to keep the delivery system moving. No
damage to adjacent tissues was seen on inspection of the
multiple repetitions of the sulcular debridement techni-
ques. On intentional exposure, directly to the tooth surface,
and no movement of the delivery system, damage to the
adjacent hard tissues was found. This moderate damage
was characteristic charring of the dentin surface, which can
be seen visually and by SEM. By comparison, scaling and
root planning with hand instrumentation caused moderate
changes to the tooth surface, not visible without magnifi-
cation. Direct intentional exposure of these lasers at high
power output results in damage to the hard tissue.
However, when the proper technique and laser parameters
are used for sulcular debridement, no evidence of hard
tissue alteration is seen. It is theorized that inadvertent
exposure would produce similar results clinically, resulting
in visible charring of the root surface. This is clinically
important because of the need to avoid surface charring
when performing sulcular debridement and soft tissue
surgery around teeth.
The histologic model allows for the determination of the
cutting and coagulation in vitro. It is easy to obtain fresh
tissues and allows for multiple laser parameters to be
tested at relatively low cost. In order to measure the
inflammation and healing events, then an in vivo model
must be utilized. In vivo experimentation is expensive and
very time consuming. It is preferable to utilize the in vitro
model first to survey a large number of laser parameters
and evaluate the tissue effects. If needed, an in vivo model
can then be utilized, with less parameters studied and
greater costs, but will allow for healing events to be
determined.
CONCLUSION
All laser parameters studied were able to reach the
defined simulation objectives in reasonable amounts of
time, less than a minute for excision and are equivalent to
other lasers tested previously. This study also provides
preclinical safety and effectiveness data for the use of
microsecond-pulsed CO
2
lasers for incision and sulcular
debridement. Sulcular debridement with microsecond
pulses and small beam diameters is possible with newer
CO
2
lasers. Direct exposure to tooth and root surface should
be avoided.
ACKNOWLEDGMENTS
This work was partially supported by a research grant
from Great Planes Technology, Inc. (GPT, Fairfield,
Nebraska). We are thankful to Dr. Dan Fried for the pulse
duration measurements, Larry Watanabe for the scanning
electron microscopy analysis.
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MICROSECOND-PULSED CO
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LASER PARAMETERS 263
... Arashiro et al. [14] found that the width of the coagulation layer in an incision of porcine skin with the CO 2 laser continuous mode at 6 W was 100-300 µm. Similarly, Vaderhobli et al. [15] and Cercadillo-Ibarguren et al. [16] reported a width <200 μm in an incision of porcine tongue with the microsecond pulsedmode CO 2 laser at 0.2-3.5 W. Therefore, the use of ultrapulsed CO 2 laser can permit true "micron-level" tissue debridement, achieving wound treatment with an unprecedented precision. Meanwhile, CO 2 laser may play a role in hemostasis, and control of local infection during the treatment of skin wounds [6][7][8][9] to promote faster wound healing. ...
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Background and Objectives Chronic wound repair is a major problem in wound treatment. Recently, several studies have suggested that carbon dioxide (CO2) laser can be used to improve the healing of chronic wounds. The aim of the present study was to preliminarily investigate the efficacy of laser debridement in treating chronic wound through a comparison of traditional instrument/surgical debridement with the ultrapulsed CO2 laser debridement in terms of wound healing, wound infection control, and wound blood perfusion. Study Design/Materials and Methods Patients with chronic wound admitted to the Wound Repair Clinic at The Affiliated Hospital of Southwest Medical University (Luzhou, China) between February 2019 and May 2019 were enrolled. They were randomly divided into two groups. The patients in one group were treated with traditional sharp instrument/surgical debridement (RT group; number of wounds: 28), while the patients in the other group were treated with ultrapulsed CO2 laser debridement (LT group; number of wounds: 26). An intergroup comparison was performed based on parameters, such as wound healing, wound infection control, and changes in wound blood perfusion. Results The wound healing rate and the total time to achieve healing were significantly better in the LT group versus the RT group at 7, 14, 21, and 28 days after treatment. The wound exudation scores were significantly higher in the LT group versus the RT group at 7, 14, and 28 days after treatment. The positive rate of pre‐debridement bacterial culture was significantly lower in the LT group versus the RD group at 14 and 28 days after treatment. The percentage of wound perfusion/normal periwound skin perfusion was significantly higher in the LT group versus the RT group at 1, 7, and 14 days after treatment. Conclusion For the treatment of chronic refractory wounds, the ultrapulsed CO2 laser exhibits higher accuracy, more effectively controls wound infection, promotes an increase in wound blood perfusion, and achieves faster wound healing compared with traditional sharp instrument/surgical debridement. Lasers Surg. Med. © 2020 Wiley Periodicals LLC
... Specific indications for use in dentistry include apthous ulcer treatment, coagulation of extraction sites, sulcular debridement, and intraoral soft tissue surgeries such as ablating, incising, and excising. The benefits of using laser versus scalpel during soft tissue surgery, include relatively bloodless surgery with little if any bleeding post-surgery; site-specific wound sterilization; minimal swelling and scarring; reduced necessity for suturing; decreased incidence of mechanical trauma; shorter operative time; favorable patient acceptance; decreased use of local anesthesia; and little or no post-operative pain (Vaderhobli, et al 2010). ...
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CO 2 laser (10.6 µm) is the most often used laser in the oral surgery due to its high absorption by water of the oral tissues. Several benefits of the use of CO 2 laser have been reported for oral surgical procedures. This study aims to evaluate the effect of CO 2 laser on soft and hard oral tissues (in vitro study). This study was done on fresh tissues from sheep's head. CO 2 Surgical Laser with different operation modes was used; 0.2 mm spot size using different laser parameters on the tongue, and bone making holes, incisions and cutting. The depths and widths of holes and incisions were measured using endodontic file under magnification. The speed of incisions was calculated and the required time for cutting was measured using sport clock. The depths of holes and incisions were increasing with increasing the power density and pulse duration from 90 µs to 1.7 ms in 100 µs increments and so in CW mode (for holes 2.5 mm at 15W, for incisions 6mm at 20W). Also the diameter of holes was increasing with power (1.2 mm at 15W) .The required time for cutting was decreasing as the power increased (14.14 sec. at 25W). The use of CO 2 laser can be considered practical, effective and easy to carry out holes, incisions, and cuttings.
... Therefore, the CO 2 laser produces a relatively thin layer of coagulation around the ablated site. Arashiro et al. (26) reported that the width of the coagulation layer was 100-300 lm in an incision of porcine skin with the continuous-mode CO 2 laser at 6 W, and Vaderhobli et al. (329) reported YAG laser penetrates the hard tissues superficially (A) and water molecules and organic molecules within the hard tissues are selectively vaporized by thermal effects as they readily absorb the laser energy, thus increasing the intratissue pressure, producing vapor within the tissue and provoking "micro-explosions" (B) that cause mechanical tissue to break down by inducing micro-crack propagation and micro-fragmentation (C) and physically contribute to the water-mediated explosive ablation process (D), leaving a minimally affected layer with microstructures on the lased surface (E). Thus, the mechanism of hardtissue ablation with the Er:YAG laser has been speculated as a "photo-mechanical" or a "thermo-mechanical" effect. ...
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Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO2 , neodymium-doped yttrium-aluminium-garnet (Nd:YAG) and diode lasers have mainly been used for periodontal soft-tissue management. With development of the erbium-doped yttrium-aluminium-garnet (Er:YAG) and erbium, chromium-doped yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft-tissue management to hard-tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri-implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti-inflammatory agents, phototherapy using lasers and light-emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low- and high-level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri-implant diseases. This article discusses the outcomes of laser therapy in soft-tissue management, periodontal nonsurgical and surgical treatment, osseous surgery and peri-implant treatment, focusing on postoperative wound healing of periodontal and peri-implant tissues, based on scientific evidence from currently available basic and clinical studies, as well as on case reports. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
... The carbon dioxide (CO2) laser has been used extensively in dermatological surgery departments and is currently recognized as the gold standard for vaporization of the soft tissues [4, 5]. In the following paper, we report our experience in comparison with data already published in this field [6–45]. ...
Article
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The CO(2) laser has been used extensively in dermatological surgery over the past 30 years and is now recognised as the gold standard for soft tissue vaporization. Considering that the continuous wave CO(2) laser delivery system and the newer "superpulsed" and scanned CO(2) systems have progressively changed our practice and patient satisfaction, a long range documentation can be useful. Our experience has demonstrated that the use of CO(2) laser involves a reduced healing time, an infrequent need for anaesthesia, reduced thermal damage, less bleeding, less inflammation, the possibility of intra-operative histologic and/or cytologic examination, and easy access to anatomically difficult areas. Immediate side effects have been pain, erythema, edema, typically see with older methods, using higher power. The percentage of after-treatment keloids and hypertrophic scars observed was very low (~1%) especially upon the usage of lower parameters. The recurrence of viral lesions (condylomas and warts) have been not more frequent than those due to other techniques. Tumor recurrence is minor compared with radiotherapy or surgery. This method is a valid alternative to surgery and/or diathermocoagulation for microsurgery of soft tissues. Our results are at times not consistent with those published in the literature, stressing the concept that multicentric studies that harmonization methodology and the patient selection are vital.
... Additionally CO2 laser use has shown mixed results when used for periodontal pocket debridement in addition to mechanical debridement, pocket reduction, attachment gain, decreased microorganisms, and guided tissue regeneration cases (Convissar & Goldstein, 2003;Matthews, 2010;Wigdor et al., 1995). Porcine mandible study evaluating efficacy of newer micropulse 10.6um CO2 laser showed clinically acceptable results in coagulation, incision depth and width, time required to perform procedure, with minimal hard tissue damage on accidental exposure but surface melting with direct exposure to laser (Vaderhobli, White, Le, Ho, & Jordan, 2010). Other studies have also reported thermal side effects like dentin cracking, carbonization, and melting following CO2 laser use on root surfaces (Matthews, 2010). ...
Article
Oral surgery can be assisted by surgical lasers: diode, erbium, CO2, Nd:YAG. The surgical lasers are used in various procedures on oral soft and bone tissues: aesthetic procedures (gingival recontouring, gingival depigmentation); operculectomy; pro-prosthetic surgical procedures (remodeling of mucosa on edentulous sites, dental crown lengthening, frenectomies, vestibuloplasty); excision of gingival or mucosa hyperplasia; peri-implantitis treatment; the removal of small exophytic lesions; the removal of oral benign lesions (ranula, mucocele, pyogenic granuloma, fibrous hyperplasia, epulis fissuratum, hemangioma). For optimum effects at the level of the target oral tissues, the laser energy parameters should be set in relation to the wavelength, the type of intervention, the nature of the inflammatory process (acutechronic), the tissue penetration depth, tissue pigmentation, and systemic status. The oral surgical procedures performed by surgical lasers are recommended in modern dentistry due to lower risk of soft and hard tissues necrosis, decreased rate of complications, higher patients’ compliance (decreased postoperative pain and discomfort) and the acceleration of the healing processes.
Chapter
The main goal in the treatment of periodontitis is the removal of subgingival biofilm, bacterial endotoxins, and calculus, which are localized in the hard tissues, such as cementum, enamel, and exposed dentin. Dental lasers may contribute to the field of periodontology, where other types of therapy and protocols cannot achieve the best clinical outcome. There are two terms important for laser‐assisted periodontal therapy: laser decontamination, which defines bacteria reduction within the inflamed periodontium, implant surfaces, and the beneficial effects in the biofilm; and laser coagulation, which means sealing of the blood vessels, capillaries, and lymphatic vessels in the inflamed tissues after laser decontamination. Specifically, the following aims should be considered in the application of lasers during periodontal therapy: bacteria reduction in the periodontal pockets, removal of dental calculus and subgingival hard deposits, root planning, removal of periodontal pocket epithelium and inflamed granulation tissue, retardation of the epithelial downgrowth in the defect.
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A variety of lasers are used for many oral soft tissue procedures. Each dental laser has specific parameters giving a wide range of operation. Lasers such as the carbon dioxide, argon and diode operate in continuous wave, while Nd:YAG, Er:YAG, Ho:YAG, and Er,Cr:YSGG are free-running pulsed lasers with high peak power and very short pulse duration. Laser tissue interaction is basically a photothermal effect and the biologic effect is dependent on the laser operating parameters, such as emission wavelength, power, emission mode, pulse duration, energy/pulse, energy density, duration of exposure, total energy and tissue characteristics. This article reviews current knowledge of laser parameters, laser-tissue interaction and applied preclinical and clinical safety and effectiveness scientific support.
Article
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The use of lasers in dentistry has been considered for over 20 years. Higher-energy density lasers were shown to fuse enamel but were potentially unsafe. Subsequently, low-energy density laser radiation was shown to affect artificial caries lesion formation. Recent studies have shown that carbon dioxide lasers can successfully be used at low-energy densities to fuse enamel, dentin, and apatite. Our studies have shown that specific wavelengths are highly efficient. These wavelengths are directly related to the infrared absorption regions of apatite. We have conducted studies with enamel and dentin, using pulsed CO2 laser radiation in the 9.32-μm to 10.49-μm region with energy densities in the 10 to 50 J.cm ⁻² range. This laser treatment caused surface fusion and inhibition of subsequent lesion progression and markedly improved the bonding strength of a composite resin to dentin. Similar studies have shown no pulpal damage or permanent deleterious effect on soft tissues. This improved understanding of the scientific rationale for the interaction of CO2 lasers with teeth can lead to several clinical applications. This will depend, however, on the development of a technology to direct a specific frequency laser beam precisely to a desired site.
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Studies of the effects of carbon dioxide (CO2) lasers on dental enamel have demonstrated that surface changes can be produced at low fluences (< 10 J/cm2) if wavelengths are used which are efficiently absorbed by the hard tissues. In this study, scanning electron microscopy (SEM) was used to characterize the wavelength dependence of surface changes in dental enamel after exposure to an extensive range of CO2 laser conditions. Bovine and human enamel were irradiated by a tunable, pulsed CO2 laser (9.3, 9.6, 10.3, 10.6 microns), with 5, 25, or 100 pulses, at absorbed fluences of 2, 5, 10, or 20 J/cm2, and pulse widths of 50, 100, 200, 500 microseconds. SEM micrographs revealed evidence of melting, crystal fusion, and exfoliation in a wavelength-dependent manner. Crystal fusion occurred at absorbed fluences as low as 5 J/cm2 per pulse at 9.3, 9.6, and 10.3 microns, in contrast to no crystal fusion at 10.6 microns (< or = 20 J/cm2). Longer pulses at constant fluence conditions decreased the extent of surface melting and crystal fusion. The total number of laser pulses delivered to the tissue did not significantly affect surface changes as long as a minimum of 5 to 10 pulses was used. Within the four easily accessible wavelengths of the CO2 laser, there are dramatic differences in the observed surface changes of dental hard tissue.
Article
This study was motivated by the desire to define damage thresholds if lasers are used for preventive dentistry techniques. A large group of extracted teeth was exposed to manually pulsed bursts of energy of varying durations from a cw CO//2 laser. The teeth were examined photographically under magnification before and after irradiation, using fluorescent dye to facilitate observation of cracks in the tooth surface. In an attempt to understand the cracking phenomena, predictions of the temperatures and thermal stresses were made. The tooth surface in the vicinity of the focused beam impingement was assumed to behave as a semi-infinite solid for the short periods of time considered. Estimated stresses where cracking occurred are compared to measured values of the ultimate strength of tooth enamel. Results are shown to be in reasonable agreement with predictions. Based on this work, a criterion is given for minimizing surface damage to the tooth.
Article
A variety of lasers are used for many oral soft tissue procedures. Each dental laser has specific parameters giving a wide range of operation. Lasers such as the carbon dioxide, argon and diode operate in continuous wave, while Nd:YAG, Er:YAG, Ho:YAG, and Er,Cr:YSGG are free-running pulsed lasers with high peak power and very short pulse duration. Laser tissue interaction is basically a photothermal effect and the biologic effect is dependent on the laser operating parameters, such as emission wavelength, power, emission mode, pulse duration, energy/pulse, energy density, duration of exposure, total energy and tissue characteristics. This article reviews current knowledge of laser parameters, laser-tissue interaction and applied preclinical and clinical safety and effectiveness scientific support.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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The use of the carbon dioxide laser for the removal of soft tissue lesions in the oral cavity is presented. The laser was used to remove numerous benign lesions and growths, for incisional and excisional biopsies, and for the removal of microinvasive and macroinvasive carcinomas. Owing to its coagulation properties, the laser was used effectively in treating patients with oral lesions compounded by blood dyscrasias. Because of the advantages of a relatively bloodless surgery; decreased postoperative discomfort; minimal swelling and scarring; and the laser's ability to coagulate, vaporize, or cut, the CO2 surgical laser offers the dental surgeon a viable and in many cases an improved alternative to the scalpel. Laser techniques and several case reports are discussed.
Article
Scanning electron microscopic observations of the pulsed carbon dioxide laser effect on human enamel support microradiographic findings and indicate that this laser is significantly more efficient than the ruby laser within the limits of this investigation. Surface changes which were suggestive of fusion occurred between energy densities of 13 to 50 joules per square centimeter.
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It was the aim of this study to determine thermal and histologic events resulting from soft tissue incision with three CO2 lasers: one emitting light energy via a hollow waveguide at 9.3 microns; the others emitting light energy at 10.6 microns, one via a hollow waveguide, the other through an articulated arm delivery system. Thirty standardized incisions were made in the oral mucosa of pig's mandibles with three different lasers at actual power levels of 1, 4 and 12 W. Thermal events were recorded with thermocouples, and a histologic examination was performed to determine vertical and horizontal tissue damage as well as incision depth and width. Thermal and histologic results were related to parameters and beam characteristics rather than wavelength. In addition to wavelength, many variables can contribute to the surgical characteristics of a laser.
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Dentistry has entered the 1990s, an era of high technology. The dental laser offers the dentist not only a window, but a door into this high-tech arena. All of the advantages lasers offer, from bloodless procedures to minimal postoperative pain and from reduction of operative time to high patient acceptance, indicate that lasers are great dental instruments for today and the future. As a futuristic idea, the ideal laser for dentistry would be able to work well, not only in soft tissue, but in hard tissue. Envision a laser with multiple wavelengths in the same unit: one for incision, another for removal of hard tissue, and yet still another for making tissue "sticky" for flap placement and tissue welding. So often dentists are associated with pain, fear, and the noise of the high-speed drill. The laser certainly helps to dispel these stereotypes and apprehensions, and to bring dentistry into a new era.