Dentinal Tubules Sealing by Means of Diode Lasers (810 and 980 nm): A Preliminary In Vitro Study

Article (PDF Available)inPhotomedicine and laser surgery 31(7) · June 2013with246 Reads
DOI: 10.1089/pho.2012.3443 · Source: PubMed
Abstract
Objective: The aim of this study was to evaluate the effect on dentinal surfaces of diode lasers (810 and 980 nm) at different parameters. Materials and methods: Twenty-four caries-free human impacted wisdom teeth were used. The crowns were sectioned transversely in order to expose the dentin. The smear layer was removed by a 1 min application of ethylenediaminetetraacetic acid (EDTA). Each surface was divided into four quadrants irradiated at a different output power setting for each kind of laser: 0.8, 1, 1.6, and 2 W (energy densities: 2547, 3184, 5092, and 6366 J/cm(2), irradiation speed 1 mm/sec; optical fiber diameter: 200 μm; continuous and noncontact mode). Half of the samples were stained with a graphite paste. All specimens were sent for scanning electron microscopic (SEM) analysis. Pulp temperature increases in additional 20 teeth were measured by a thermocouple. Results: Diode laser irradiations at 0.8 and 1 W led to occlusion or narrowing of dentin tubules without provoking fissures or cracks. The application of graphite paste increased the thermal effects in dentin. Measurements of pulp temperature showed that irradiations at 0.8 and 1 W for a period of 10 sec in continuous mode increased pulp temperature (T ≤2°C). Conclusions: Diode lasers (810 and 980 nm) used at 0.8 and 1 W for 10 sec in continuous mode were able to seal the dentin tubules. These parameters can be considered harmless for pulp vitality, and may be effective in the treatment of dentinal hypersensitivity.

Figures

Dentinal Tubules Sealing by Means of Diode Lasers
(810 and 980 nm): A Preliminary In Vitro Study
Monica Umana, DDS,
1
Daniel Heysselaer, DDS,
1
Marc Tielemans, DDS,
1
Philippe Compere, Ing, PhD
2
Toni Zeinoun, DDS,
3
and Samir Nammour, DDS, PhD
1
Abstract
Objective: The aim of this study was to evaluate the effect on dentinal surfaces of diode lasers (810 and 980 nm)
at different parameters. Materials and methods: Twenty-four caries-free human impacted wisdom teeth were
used. The crowns were sectioned transversely in order to expos e the dentin. The smear layer was removed by a
1 min application of ethylenediaminetetraacetic acid (EDTA). Each surface was divided into four quadrants
irradiated at a different output power setting for each kind of laser: 0.8, 1, 1.6, and 2 W (energy densities: 2547,
3184, 5092, and 6366 J/cm
2
, irradiation speed 1 mm/sec; optical fiber diameter: 200 lm; continuous and non-
contact mode). Half of the samples were stained with a graphite paste. All specimens were sent for scanning
electron microscopic (SEM) analysis. Pulp temperature increases in additional 20 teeth were measured by a
thermocouple. Results: Diode laser irradiations at 0.8 and 1 W led to occlusion or narrowing of dentin tubules
without provoking fissures or cracks. The application of graphite paste increased the thermal effects in dentin.
Measurements of pulp temperature showed that irradiations at 0.8 and 1 W for a period of 10 sec in continuous
mode increased pulp temperature (T £ 2C). Conclusions: Diode lasers (810 and 980 nm) used at 0.8 and 1 W for
10 sec in continuous mode were able to seal the dentin tubules. These parameters can be considered harmless for
pulp vitality, and may be effective in the treatment of dentinal hypersensitivity.
Introduction
D
entin hypersensitivity is described as the response
to a stimulus that would not cause pain in a healthy
tooth under normal conditions. It is distinguished by an acute
pain of short duration from the denuded dentin. Its etiology is
unknown,
1
and seems to be a consequence of the presence of
open dentin tubules on the exposed dentin surface.
2
Bra
¨
nn-
stro
¨
m’s hydrodynamic theory
3
states that the movement of
fluid in the dentin tubules stimulates the mechano-receptors
in or near the pulp, which is the reason that the tubules’ oc-
clusion reduces dentin permeability and, proportionally, de-
creases the degree of dentin hypersensitivity.
4,5
Although many substances are available to treat dentin
hypersensitivity,
6–9
they have turned out to be ineffective
over the long term, and/or studies
10,11
have revealed con-
tradictory results. An ideal desensitizing agent should allow
occlusion of dentinal tubules without endangering the pulp,
should be relatively painless, easily applied, rapid, and
permanently effective, and should not discolor the teeth.
6,7
The results from research regarding the effect of lasers on
the treatment of dentin hypersensitivity vary, and so do the
irradiation parameters, wavelengths, and application tech-
niques.
12
In some studies, the dentin is irradiated at low
energy densities (*4 J/cm)
13,14
with the aim of stimulating
the production of tertiary dentin by the odontoblasts. On the
contrary, several studies use higher energy densities in order
to provoke a dentinal melting and occlude dentinal tubules,
but this practice can induce significant thermal effects, if laser
parameters are inadequately controlled. Studies reported
that Nd:YAG, Er:YAG, CO
2
and diode lasers produce an
efficient desensitizing effect;
7,15–18
however, subsequent fur-
ther research seems necessary
19
to define the optimal irra-
diation conditions for harmlessness to pulp and tubule
occlusion.
The aim of our study was to evaluate the alterations in dentin
irradiated with diode laser beams (810 and 980 nm) at different
parameters. We sought to establish the best laser parameter
settings to achieve a reduction in the diameter of dentin tubules
with the aim of finding a future clinical application for diode
lasers in the treatment of dentin hypersensitivity.
Materials and Methods
The approval of the local research ethics committee is not
required in our University for this kind of protocol.
1
Department of Dental Sciences, Faculty of Medicine, University of Lie
`
ge, Quai Godfroid Kurth, Lie
`
ge, Belgium.
2
Unit of Ultra-structural Morphology, Laboratory of Evolutive and Functional Morphology, Lie
`
ge, Belgium.
3
Department of Dental Sciences, Faculty of Medicine, University of Lie
`
ge, Quai Lie
`
ge, Belgium.
Photomedicine and Laser Surgery
Volume 31, Number 7, 2013
ª Mary Ann Liebert, Inc.
Pp. 1–8
DOI: 10.1089/pho.2012.3443
1
Twenty-four caries free adult (18–25 years of age) human
impacted wisdom teeth extracted by surgery were kept in
balanced salt solution
20
at 4C during 1 week. The external
surfaces were cleaned using a scaler, and, immediately, teeth
were sectioned transversely at the mid-level of the crowns at
a low speed (300 rpm) using a precision sectioning 20 LC
diamond blade (Isomet
Low Speed Saw, Buehler
Ltd.,
Lake Bluff, IL) in order to totally expose the dentin. The
exposed dentinal surfaces of these discs were polished with
Soft-Lex discs 3M Espe (coarse-grit disc and medium-grit)
using a handpiece speed of 12,000 rpm for 20 sec. Then they
were rinsed with cool water and dried with a 5 sec air blast.
21
Each exposed dentinal surface was divided into four
quadrants with a 10 mm long, standard grit diamond bur
(C4, 10 mm long, standard grit, Crosstech Diamond Instru-
ments Ltd., Thailand) under cooling water.
The smear layer was removed by a 1 min application of
18% ethylenediaminetetraacetic acid (EDTA) (Ultradent
Products, Inc, USA). Teeth were rinsed with distilled water
and immediately irradiated at different energy densities for
each kind of laser.
The first group was irradiated with the 810 nm diode
(Elexxion Claros Nano, Germany), whereas we used the
980 nm diode laser (Biolitec, Germany) for the second group.
The parameters used for both groups were the following:
continuous, tangential, noncontact mode (the distance between
the optical fiber and the irradiated surface was 1 mm), deliv-
ered energy densities per second 2547, 3184, 5092, and 6366 J/
cm
2
for the following output power settings: 0.8, 1, 1.6, and
2 W. The optical fiber diameter was 200 lm. Irradiation speed
was 1 mm/sec. Specimens were placed on a flat surface; the
optical fiber was moved by the operator tangentially (45 de-
gree angle) at *1 mm/sec speed. The tangency of irradiation
and the speed were controlled and appreciated by the operator
with possible human error.
Half of the specimens of each group were stained with a
graphite paste obtained by mixing distilled water and fine
grain (particle size 25–50 lm) graphite powder (Pressol,
Nuremberg, Germany) as an enhancer. Subsequently, these
samples were carefully rinsed with distilled water in order to
eliminate the residual graphite that could be easily removed
because its particle size is larger than average diameter of
dentinal tubules.
Scanning electron microscopy (SEM) analysis
The specimens were dehydrated in blue silicon (with a
humidity indicator) at room temperature. At that point, they
were attached to aluminum stubs and metallized with a
layer of gold (25 nm thick), using vacuum evaporation in a
metallizer (model SCD 005, Bautec, Berlin, Germany).
22
The
samples were analyzed by SEM (Jeol JSM 840-A, Japan) and
were observed under 1500x magnification.
Pulp temperature increase measurements
To assess temperature variations, 20 additional teeth were ir-
radiated. Half of them were lased with an 810 nm diode laser and
the other half were irradiated by a 980 nm diode laser. Five
measurements with and without graphite paste were per-
formed per tooth in each group. The irradiation parameters were:
0.8, 1, 1.6, and 2 W. Fiber diameter was 200 lm. Delivered energ y
densities per second were 2547, 3184, 5092, and 6366 J/cm
2
.
Scanning speed was 1 mm/sec. Continuous and noncontact
modes were used for 10 sec.
We followed the protocol used in previous studies for the
measurements of pulp temperature increase during laser ir-
radiation.
23–29
The thickness of the dentin between the ex-
posed dentinal surfaces and the pulp roof was 1 mm, and
this measurement was further confirmed by radiography
complemented by a millimeter grid.
The pulp chamber was filled with a thermoconductor paste
(Prosilican thermal compound: warme Leitpaste WPN 10;
Austerlitz electronic, Nuremberg 1, Germany). It was injected
by a Lentulo compactor into the cameral pulp cavity to ensure
optimal contact and maximal thermal conduction between the
sensor tip of the thermocouple probe and the roof of the
cameral pulp. The thermal conductivity of the paste amoun-
ted to 0.4 cal s
- 1
m
- 1
K
- 1
. This is comparable to the ther-
mal conductivity of soft tissues (0.2 0.5 cal s
- 1
m
- 1
K
- 1
depending upon hydration).
30
The temperature at the roof of the cameral pulp and that
of the room were compared in order to record the variations
of temperature (D TC).
AtypeKthermocouplewasused(ModelTM–946,4
channels, Lutron, Taiwan), with an accuracy of 0.01C.
One thermocouple probe was placed in close contact with
the roof of the cameral pulp. A secon d probe was placed
at room temperature to compare temperat ure changes
at the roof of t he cameral pulp with changes in room
temperature.
Once the base pulp temperature became stable after 30 sec,
we started measuring the temperature variations. Pulp
temperature was recorded every second for 180 sec after the
end of the irradiation. Five records were repeated for each
irradiation parameter.
The considered temperatures (Dt) were calculated as the
difference between recorded temperatures at the roof of the
cameral pulp (Tcp) and recorded room temperatures (TRT):
Dt = Tcp - TRT.
The mean of recorded temperatures (Dt) and the standard
deviation for each irradiation condition were calculated.
FIG. 1. Scanning electron microscopic (SEM) view of un-
lased dentin (control) treated only with ethylenediaminete-
traacetic acid (EDTA) (18%). The dentin is not covered by the
smear layer. The tubules are open. Magnification: 1500 · .
2 UMANA ET AL.
Normality tests were performed using the Kolmogorov and
Smirnov (KS) test.
Results
The nonirradiated control group presented open tubules,
absence of the smear layer, and a regular aspect, which is a
standard pattern of dentin treated with EDTA
29,30
(Fig. 1).
SEM analysis of the irradiated dentin surface showed
surface structural changes caused by laser irradiation.
A narrowing of the dentinal tubules was observed at
delivered output powers of 0.8–1.6 W for 810 nm diode
laser ( Figs. 2 and 3) and 0.8–1 W for 980 nm diode laser
(Fig. 4).
The dentin showed melting areas and a total occlusion of
tubules at 2 W for 810 nm diode laser (Fig. 3) and at 1.6–2 W
for 980 nm diode laser (Fig. 5). At 2 W, 980 nm diode laser
irradiation provoked some areas of dentinal ablation and
destruction (Fig. 5).
Samples stained with graphite paste
The graphite absorbed the laser beam intensely. This ab-
sorption generated an important source of heat and in-
creased the effect of the diode beam. Therefore, the dentin
surfac2e presented areas of fusion, melting, and cracks.
At 0.8–1 W, 810 nm diode laser irradiation reduced the
diameter of the dentinal tubules (Fig. 6). Higher output
powers (1.6 and 2 W) produced dentinal melting, craters,
and loss of substance (Fig. 7).
At 0.8–1 W, 980 nm diode laser irradiation, the dentinal
surface appeared irregular and scaly with a total occlusion of
dentinal tubules (Fig. 8). At higher output powers (1.6 and
2 W), melted dentinal areas with loss of substances were
noticed (Fig. 9).
FIG. 2. Scanning electron microscopic (SEM) views of treated dentin by diode laser (810 nm) at (a) 0.8 W and (b) 1W.
A znarrowing of dentinal tubules can be noted (arrows). Magnification: 1500 · .
FIG. 3. Scanning electron microscopic (SEM) views of treated dentin by diode laser (810 nm) at (a) 1.6 W and (b) 2W.
A narrowing of dentinal tubules can be noted at 1.6 W (arrow), whereas at 2 W, some tubules are completely occluded
(arrow). Magnification: 1500 · .
DETINAL TUBULES SEALING BY MEANS OF DIODE LASERS 3
Measurements of temperature
After 10 sec of irradiation (1 mm/sec; power range: 1–2
W), the means and standard deviations of temperature
increases at the roof of the cameral pulp were between
0.8–2.30C and 0.4–1.3C, respectively, for the irradiation
using a diode laser (980 nm) with and without graphite. The
cameral pulp temperature rise ranged from 1.7C to 3.5C
and from 0.9Cto2C, respectively, for the diode laser
(810 nm) irradiations with and without graphite.
Pulp temperature recordings showed that the samples ir-
radiated by 810 nm diode laser at 2 W (with graphite) pre-
sented the highest values, 3.26 0.251C (higher than the
safety level of 3 C for pulp injury).
Tables 1 and 2 show the mean, minimal, and maximal
values of pulp temperature increase for each group.
All samples in each group passed the normality test (KS)
with a p value > 0.05.
Discussion
Diode lasers provide an abundance of available wave-
lengths in the visible and infrared spectrum. Near infrared
(NIR) lasers are characterized by a high absorption in chro-
mophore found in soft tissue. For this study, we selected the
810 and 980 nm wavelengths, the most commonly used
wavelengths in dentistry, especially in endodontics and
periodontics.
12,31
They can be modulated in continuous wave
(CW) or pulsed mode.
12,31
The wavelength of a laser determines its level of absorption
and interaction with the tissue. The absorption coefficient is a
measure of the level of absorption that occurs in a specific
tissue by a specific wavelength. A high absorption coefficient
means that less energy is needed to get the same local heating
effect.
12
The coefficient la(cm- 1) characterizes the absorption.
The absorption coefficients of diode lasers in dental tissues are
low: *0.1 cm
- 1
in dentin and 10 cm
- 1
in the pulp.
32
FIG. 4. Scanning electron microscopic(SEM) views of treated dentin by diode laser (980 nm) at (a) 0.8W and (b) 1 W. A narrowing
of the dentinal tubules can be noted (arrow). At 1 W, some tubules are occluded (arrow). Magnification: 1500 and 1200 · .
FIG. 5. Scanning electron microscopic (SEM) views of treated dentin by diode laser (980 nm) at (a) 1.6 W and (b) 2W.At1.6
W, some tubules are completely occluded (arrow), whereas at 2 W, some areas with dentinal ablation can be noted (arrows).
Magnification: 1500 · .
4 UMANA ET AL.
FIG. 6. Scanning electron microscopic (SEM) views of treated and graphite-stained dentin by diode laser (810 nm). At (a) 0.8
W and (b) 1 W, a narrowing of dentinal tubules can be noted (arrows). Magnification: 1500 · .
FIG. 7. Scanning electron microscopic (SEM) views of
treated and graphite-stained dentin by diode laser (810 nm)
at (a) 1.6 W and (b) 2 W. Some tubules are completely oc-
cluded, whereas some areas with dentinal ablation can be
noted (narrows). Magnification: 1500 · .
FIG. 8. Scanning electron microscopic (SEM) views of
treated and graphite-stained dentin by diode laser (980 nm)
at (a) 0.8 W and (b) 1 W. The tubules are completely oc-
cluded, whereas multiple areas with dentinal ablation can be
noted at 1 W (arrow). Magnification: 1500 · .
DETINAL TUBULES SEALING BY MEANS OF DIODE LASERS 5
A laser wavelength of between 800 and 980 nm is poorly
absorbed in water and hydroxyapatite.
12,32
This low ab-
sorption in dental tissues allows propagation, scattering, or
diffused transmission of the laser radiation through the
dentin, and important thermal effects.
32–34
The energy ab-
sorbed by the dentin surface provokes a sufficient increase in
temperature to obtain a melting effect and reduce or close the
dentinal tubules.
In our research, the chosen parameters were selected after
prior tests. According to literature, diode lasers are able to
seal dentinal tubules in a far lesser degree than other lasers
(Er; Cr: YSGG, and CO
2
) with negligible effects on desensi-
tization.
35
A previous study showed that the irradiation of
980 nm diode laser in dentin at different output powers and
delivery modes produced changes that ranged from smear
layer removal to dentine fusion.
36,37
Continuous wave mode was employed because it is easier
for the operator to scan the whole dentin surface in this way.
Nevertheless, pulsed mode can also be useful because it
enables the target tissue to cool between successive pulses,
but this should be the objective of future studies. We selected
the noncontact mode to protect the optical fiber from the
graphite paste. The tangentially mode (45 degree angle) was
preferred in the aim to avoid a direct pulp exposure by the
part of the beam not absorbed by dentin.
The action mechanism of the diode laser (980 nm) in
dentin substrate is approximately similar to the Nd:YAG
laser (1064 nm). As both systems are in the NIR portion of the
electromagnetic spectrum,
38
part of the energy is absorbed
by the mineral structures of dentin such as phosphate and
carbonate, disarranging the crystalline arrangement because
of thermochemical ablation and provoking melting of the
dentin tissue.
39,40
These transformations are more intense
when higher parameters are used.
41
SEM analysis was used
to verify ultrastructural changes of the irradiated dentine.
Oral tissues contain several chromophores: hemoglobin,
melanin, and other pigmented proteins and (carbonated)
hydroxyapatite. The absorption coefficients for the listed
chromophores with regard to the wavelengths used in
dental lasers is variable. Generally, pigmented tissues will
better absorb visible or NIR wavelengths, whereas un-
pigmented tissues absorb longer wavelengths. Diode lasers
are more absorbed in melanin and other pigments than in
dentin.
In the present study, it was found that the diode laser
beam absorption could be highly increased in a pigmented
surface. We stained half of the samples with a graphite paste
(graphite powder and water). The application of graphite
paste enhances the effects of the diodes on the dentin surface.
It provokes an important increase of temperature to reduce or
close the dentinal tubules by a melting effect, but it can also
provoke cracks and destruction at highest energy densities.
The wavelength of 980 nm was absorbed the most by
water but the 810 nm had a greater absorption in melanin.
The higher absorption by dentinal water of the 980 nm diode
laser may explain its lower pulp temperature increase com-
pared with the 810 nm diode laser.
42–44
FIG. 9. Scanning electron microscopic (SEM) views of
treated and graphite-stained dentin by diode laser (980 nm)
at (a) 1.6 W and (b) 2 W. The tubules are completely oc-
cluded, whereas many areas with dentinal ablation can be
noted (arrows). Magnification: 1500 · .
Table 1. Pulp Temperature Increase Following
Different Diode Laser (980 nm) Irradiation Settings
1W1W–G*1.6W1.6W–G*2W2W–G*
Minimum 0.4 0.8 0.7 1.4 1.1 1.8
Maximum 0.7 1.2 0.8 1.6 1.3 2.3
Mean 0.58 1.03 0.77 1.53 1.18 2.1
Std.
deviation
0.13 0.21 0.06 0.12 0.1 0.24
G*, dentinal surface smeared with graphite.
Table 2. Pulp Temperature Increase Following
Different Diode Laser (810 nm) Irradiation Settings
1W
1W–
G* 1.6 W
1.6 W
G* 2 W
2W–
G*
Minimum 0.9000 1.7000 1.4000 2.1000 1.8000 2.9000
Maximum 1.0000 1.9000 1.7000 3.0000 2.0000 3.5000
Mean 0.9800 1.8200 1.5330 2.4400 1.9330 3.2600
Std.
deviation
0.0447 0.0837 0.1528 0.3362 0.1155 0.2510
G*, dentinal surface smeared with graphite.
6 UMANA ET AL.
A 2.5C temperature threshold for the survival of the
pulp tissue was established in classical study of Zach
and Cohen.
45
Nowadays, an increase in temperature of
3C is deemed to be the maximum ceiling to not produce
irreversible pulpal damage.
46
On the one hand, the temperature measurements revealed
that 810 and 980 nm diode laser irradiation up to 2 W cannot
be dangerous to the pulp tissues, but on the other hand, the
application of graphite produces temperature elevations,
which could exceed the safety level for irradiation by the
810 nm diode laser.
This in vitro study provides an approximate assessment of
the temperature increase at the level of the pulp roof. The
degree of water content in dentin is certainly different from
in in vivo conditions. The laser beam was stopped at the
surface of the exposed dentin and the thermocouple was
placed at a 1 mm distance from it. The possibility of elec-
tromagnetic interference of lasers on the thermocouple is an
inherent difficulty of this type of in vitro measurement of
temperature increases.
Our preliminary in vitro study aimed to verify the possi-
bility of narrowing or occluding dentinal tubules by means
of diode lasers 810 and 980 nm.
Nevertheless, as demonstrated by other authors,
19
further
clinical studies need to be conducted in order to confirm
these in vitro results before definitive conclusions can be
drawn and before use in the treatment of dentin hypersen-
sitivity.
Conclusions
Our results confirmed that 810 and 980 nm diode laser
irradiation (0.8–1 W, continuous mode, irradiation speed:
1 mm/sec for 10 sec, laser fiber diameter: 200 lm) can lead to
dentinal melting and to the narrowing of dentinal tubules.
Higher energy densities (1.6–2 W) produce an important
destruction of the dentinal surface and hence damage the
dental pulp.
The application of a chromophore (graphite paste) en-
hances the thermal effects of the diodes on the dentin surface;
it increases the areas of fusion and destruction at high energy
densities (1.6–2 W).
Author Disclosure Statement
No competing financial interests exist.
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Address correspondence to:
Monica Umana
37, rue Duranton
75015 Paris
France
E-mail: m18m94@hotmail.com
8 UMANA ET AL.
    • "Kim et al. [20] demonstrated the feasibility of tubules occlusion by using a CO 2 laser and nanocarbonate apatite, while Han et al. [21] also succeeded in occluding dentinal tubules by replacing the CO 2 laser by an Er:YAG laser. Umana et al. [19] succeeded in occluding dentinal tubules using diode lasers (810 nm and 980 nm) in combination with graphite paste. Farmakis et al. [22] showed the possibility to occlude tubules using the combination of bioglass and Nd:YAG laser. "
    [Show abstract] [Hide abstract] ABSTRACT: Objective. The aim of this study is to evaluate the effectiveness of Nd:YAP laser to seal dentinal tubules at different parameters. Material and Methods. 24 caries-free human wisdom impacted molars were used. The crowns were sectioned transversally in order to totally expose the dentin. The smear layer was removed by a 1 min application of EDTA. Each surface was divided into four quadrants, but only three quadrants were irradiated at a different output power setting (irradiation speed: 1 mm/sec; optical fiber diameter: 320 µm; tangential incidence of beam and in noncontact mode). Samples were smeared with a graphite paste prior to laser irradiation. All specimens were sent for SEM analysis. Pulp temperature increases in additional twenty teeth were measured by a thermocouple. Results. Morphological changes in dentin surfaces depend on the value of used energy density. Higher energy densities (2 W–4 W; 200–400 mJ; pulse duration: 100 m sec.; and 10 Hz) induce higher dentin modifications. Our results confirmed that Nd:YAP laser irradiations can lead to total or partial occlusion of dentin tubules without provoking fissures or cracks. Measurements of pulp temperature increases showed that Nd:YAP laser beam can be considered as harmless for pulp vitality for following irradiation conditions: 2 W (200 mJ) to 4 W (400 mJ) with an irradiation speed of 1 mm/sec; fiber diameter: 320 micrometers; 10 Hz; pulse duration: 100 m sec; noncontact mode and in tangential incidence to exposed dentin. The perpendicular incidence of the laser beam on exposed dentin may injure pulp vitality even at low output power of 3 W. Conclusions. Nd:YAP laser beam was able to seal the dentin tubules without damaging dentinal surfaces and without harming pulp vitality. Nd:YAP laser is effective and may be safely used for future in vivo treatments of dentinal hypersensitivity under certain conditions.
    Full-text · Article · Oct 2014
  • [Show abstract] [Hide abstract] ABSTRACT: Dentin hypersensitivity (DH) is one of the most frequent problems causing patients' complaints following stimulation of cervically exposed dentin. Studies have shown that different lasers have various occluding effects on dentinal tubules. This study is aimed at evaluating the occluding effects of Er;Cr:YSGG (P:0.25W,F:20Hz,Pd:140μS), Nd:YAG (P:1W,F:20Hz), CO(2) (P:1W, Pd:50μs), and 810-nm diode (P:2 W, Pd:30ms) lasers on dentinal tubules. Fifteen human third molars were collected and ground-sectioned vertically on the buccal and lingual surfaces to yield two dentin disks of 2-mm thickness. Then, four sites for laser irradiation and one control site were marked in the cervical areas of the dentin disks. Before laser application, specimens were exposed to a 14% EDTA solution to expose dentinal tubules and were then evaluated by scanning electron microscopy (SEM). The tubules' entrance diameters were determined by "scale-bar" software (Phillips Scale-Bar, Phillips, Amsterdam, The Netherlands), which is specifically designed for SEM. The mean diameters for the tubules were then estimated for each site and analyzed statistically. The mean dentinal tubule entrance diameters for Er;Cr:YSGG, 810-nm diode, CO(2), and Nd:YAG, were 1.73, 3.27, 2.10, and 1.64 microns, respectively, compared with 3.52 microns before laser irradiation. Overall, the furthest reduction in mean tubule diameter resulted from the Nd: YAG laser (53%). However, tubular diameter reduction in all laser groups (p<0.05) was found to be statistically significant. In all laser groups, melting of the peritubular dentin was the dominant observed phenomenon. Our results indicate that Nd: YAG, Er; Cr: YSGG, and CO(2) lasers, through their ability to melt peritubular dentin, can occlude dentinal tubules partially or totally, and therefore reduce patients' hypersensitivity symptoms. The 810-nm diode laser sealed tubules to a far lesser degree, with negligible effects on desensitization.
    Article · Feb 2011
  • [Show abstract] [Hide abstract] ABSTRACT: Dentin hypersensitivity is one of the most common complications that affect patients after periodontal therapy. Recently low level laser therapy has been introduced as a new treatment modality and has produced beneficial results. The purpose of this study is to evaluate the effect of low level laser therapy toothbrushes in reduction of dentin hypersensitivity. In this pilot interventional controlled clinical trial, 40 patients suffering from dentin hypersensitivity were selected using simple randomization. Half of the patients were given laser toothbrushes and the other half was given non-laser sensodyne toothbrushes. Primary dentin hypersensitivity was recorded by visual analogue scale (VAS) score and ice spray. Then dentin hypersensitivity was measured right after the treatment as well az in the intervals of 1 month and 2 months after initiation of the study. Data were compared using Statistical Package for the Social Sciences (SPSS) software and Analysis of variance (ANOVA) paired T test. The results of this study showed that there was a significant difference in each of the two kinds of tooth brushes separately for all time intervals (P < 0.001). Also the effect of the type of toothbrush was investigated using before treatment VAS with covariance analyses. P values for immediately, 1 month and 2 months after treatment were calculated to be 0.078, 0.02, 0.01 respectfully. Also the effect of the toothbrush type was significant in the manner that laser toothbrushes reduce dentin hypersensitivity more than ordinary toothbrushes (P< 0.05). Both sensodyne and laser tooth brushes improve dentin hypersensitivity, although the laser toothbrush led to better results in short.
    Article · May 2015
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