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Journal of the Laser and Health Academy
Vol. 2013, No.1; www.laserandhealth.com
ISSN 1855-9913
Quality of Restorations Performed with QSP Mode
Aslihan Usumez
Bezmialem Vakif University Faculty of Dentistry Department of Prosthodontics
SUMMARY
Er:YAG lasers represent a promising technology
with various applications in every field of Dentistry.
Compared with other lasers, Er:YAG can effectively
alter enamel and dentin surface because of its 2940 nm
wavelength emission, which is coincident with the
main absorption band of water and OH- groups in
hydroxyapatite.[1] Laser irradiation parameters define
the exact interaction of the laser on the tissue. Pulse
duration is an important factor for the ability of a laser
to perform surface modification.[2] Active electronic
control of laser pulse duration and amplitude is
possible today with the development of Variable
Square Pulse® technology (Fotona, Ljubljana,
Slovenia). With VSP, the duration of pulses can be
adjusted from 50 μs (super-short pulse) to 100 μs
(very short pulse), 300 μs (short pulse), 600 μs (long
pulse) and 1,000 μs (very long pulse). Because of its
higher energy in the shorter pulses, the energy loss
through heat is lower. As a result of this, ablation
becomes more effective and a thermal effect is not
evident on the tissue.[3]
The Quantum Square Pulse (QSP) mode has also
recently been introduced in Er:YAG laser technology.
In QSP mode, each pulse is split into several shorter
pulses that follow each other at an optimally fast rate.
In this way, absorption and scattering of the laser
beam is avoided and undesirable thermal effects for
the tissues are decreased.4 Lasers operating at this
mode are reported to provide fast and precise hard
dental tissue preparation.[5]
When the effects of different Er:YAG laser pulse
modes (MSP and QSP) on the microleakage of
composite resin restoration (Clearfil Majesty Posterior,
Kuraray) using a self-etch adhesive systems were
evaluated, the cavities etched with Er:YAG laser QSP
mode showed less microleakage than MSP mode
etched and acid-etched surfaces.
The QSP mode is also successful in the etching of
enamel surfaces for orthodontic bonding. Er:YAG
laser etching with QSP mode presents a successful
alternative to acid etching by providing higher or
comparable shear bond strength values. The Scanning
Electron Microscope (SEM), Atomic Force
Microscope (AFM) and surface profilometry utilized
in the study demonstrated successful alterations of the
enamel surface with this technology (Figure 1-3).[6]
Fig. 1: Atomic force microscope scan of an enamel surface
etched with 37% phosphoric acid.
Fig. 2: Atomic force microscope scan of an enamel surface
etched with MSP mode Er:YAG laser.
Fig. 3: Atomic force microscope scan of an enamel surface
etched with QSP mode Er:YAG laser.
To evaluate the microtensile bond strength (μTBS)
of a self-etch adhesive to dentin after treatment with
Er:YAG laser using different pulse durations and
parameters, the dentin surfaces were irradiated with an
Er:YAG laser with the following parameters: (1) energy
output: 200 mJ or 120 mJ; (2) water cooling: 50 ml/min
or 25 ml/min; (3) pulse duration: MSP mode or QSP
mode. The Er:YAG laser irradiation increased the
μTBS of the adhesive-to-dentin surface when compared
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with the results of self-etch adhesive alone. Among the
Er:YAG laser irradiated surfaces, the highest μTBS
result was achieved in the low-energy output and lowwater cooling applied group (Figures 4-7).
Fig. 7: SEM view of the interface between dentin etched
with QSP mode Er:YAG laser and composite resin.
Fig. 4: SEM view of dentin surface etched with MSP mode
Er:YAG laser.
According to the results of the current studies, it
can be concluded that the QSP mode of the Er:YAG
laser is a very effective and promising new pulse mode
for preparing surfaces for the bonding of resin
materials on hard dental tissues.
REFERENCES
1.
2.
3.
Fig. 5: SEM view of the interface between dentin etched
with MSP mode Er:YAG laser and composite resin.
4.
5.
6.
Fig. 6: SEM view of dentin surface etched with QSP mode
Er:YAG laser.
Firat E, Gurgan S, Gutknecht N. Microtensile bond strength of
an etch-and-rinse adhesive to enamel and dentin after Er:YAG
laser pretreatment with different pulse durations. Lasers Med Sci
2012;27:15-21.
Lukac M, Marko M, Ladislav G. Super VSP Er:YAG pulses for
fast and precise cavity preparation. J Oral Laser Applic.
2004;4:171–173.
Grgurevic J, Grgurevic L, Miletic I, Karlovic Z, Jukic Krmek S,
Anic I. In vitro study of the variable square pulse Er:YAG laser
cutting efficacy for apicectomy. Lasers Surg Med. 2005;5:347–
350.
Gutknecht N, Lukac M, Marincek M, Perhavec T, Kazic M. A
Novel Quantum Square Pulse (QSP) Mode Erbium Dental Laser.
J LAHA. 2011;1:15-21.
Lukac M, Primc NM, Pirnat S. Quantum Square Pulse Er:YAG
Lasers for fast and precise hard dental tissue preparation. J
LAHA. 2012;1:14-21.
Sagır S, Usumez A, Ademci A, Usumez S. Effect of enamel laser
irradiation at different pulse settings on shear bond strength of
orthodontic brackets, Angle Orthodontics, In press.
The intent of this Laser and Health Academy publication is to facilitate an exchange
of information on the views, research results, and clinical experiences within the
medical laser community. The contents of this publication are the sole responsibility
of the authors and may not in any circumstances be regarded as official product
information by medical equipment manufacturers. When in doubt, please check with
the manufacturers about whether a specific product or application has been approved
or cleared to be marketed and sold in your country.
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