Download effect of surface treatment on shear bond strength of orthodontic

CLINICAL DENTISTRY AND RESEARCH 2015; 39(3): 110-117 Original Research Article
EFFECT OF SURFACE TREATMENT ON SHEAR BOND STRENGTH
OF ORTHODONTIC BRACKETS
Fidan Alakus Sabuncuoğlu, DDS, PhD
Postgraduate Resident, Department of Orthodontics,
Center for Dental Sciences, Maresal Çakmak Hospital,
Erzurum, Turkey
Seyda Ersahan, DDS, PhD
ABSTRACT
Background and Aim: To compare the effects of different
methods of surface treatment on the shear bond strength (SBS)
and fracture mode of orthodontic brackets.
Postgraduate Resident, Department of Endodontics,
Materials and Methods: Sixty premolars were randomly divided
Center for Dental Sciences, Beytepe Hospital,
into six groups (n=10) according to type of enamel surface
Ankara, Turkey
treatment: I, acid etching; II, Nd:YAG laser; III, Nd:YAG laser+acid-
Ergül Ertürk, DDS, PhD
etching; IV, Er:YAG laser; V, Er:YAG+acid-etching; VI, sandblasting with
Postgraduate Resident, Department of Prosthodontics,
aluminum oxide. Brackets were fixed on the treated enamel surface
Center for Dental Sciences, Maresal Cakmak Hospital,
with adhesive resin and subjected to SBS testing. Specimens were
Erzurum, Turkey
evaluated using the Adhesive Remnant Index (ARI), and failure
modes were quantitatively assessed using a stereomicroscope.
Statistical analysis was performed using one-way analysis of
variance and the post-hoc Tukey test, with the significance level set
at 0.05.
Results: The highest SBS values were observed for Group
V, although the difference between Groups V and III was not
significant. SBS values for the sandblasting group (Group VI) were
significantly lower than all other groups. While Group I, II and IV
exhibited similar bracket failure modes (p>0.05), which were mainly
failures at the enamel-resin interface, with less than 50% of the
adhesive remaining (ARI: 1), Group III and V showed mainly failures
at the enamel-resin interface, with more than 50% of the adhesive
remaining (ARI: 2).
Correspondence
Conclusion: Surface treatment of enamel with a combination of
Fidan Alakuş Sabuncuoğlu, DDS PhD
Er:YAG laser and acid-etching results in significantly higher SBS than
Department of Orthodontics,
acid-etching or laser irradiation alone. Both laser irradiation alone
Center for Dental Sciences,
or in combination with acid-etching can be recommended as viable
Maresal Çakmak Hospital,
treatment alternatives to acid etching.
Erzurum, Turkey
Phone: 0532 7228904
E-mail: [email protected]
110
Clin Dent Res 2015: 39(3): 110-117
Submitted for Publication: 09.24.2015
Keywords: Er-YAG Laser, Nd:YAG Laser, Orthophosphoric Acid,
Accepted for Publication : 12.04.2015
Shear Bond Strength, Sandblasting
CLINICAL DENTISTRY AND RESEARCH 2015; 39(3): 110-117
Orjinal Araştırma
YÜZEY TEDAVİSİNİN ORTODONTIK BRAKETLERİN MAKASLAMA
BAĞLANMA DAYANIMI ÜZERİNE ETKİSİ
Fidan Alakuş Sabuncuoğlu,
Dr, Marasal Cakmak Asker Hastanesi,
Diş Servisi Ortodonti Bölümü,
Erzurum, Türkiye
ÖZ
Amaç: Farklı yüzey tedavi metotlarının ortodontik braketlerin
makaslama bağlanma dayanımı (SBS) ve kırılma tipine etkilerinin
karşılaştırılması.
Seyda Ersahan,
Dr. Beytepe Asker Hastanesi Diş Servisi,
Endodonti Bölümü,
Ankara, Türkiye
Material ve Metod: Mine yüzey tedavi çeşidine göre altmış
premolar rastgele altı gruba ayrıldı (n=10): I, asitle pürüzlendirme; II,
Nd:YAG lazer; III, Nd:YAG lazer+asitle pürüzlendirme; IV, Er:YAG lazer;
V, Er:YAG+asitle pürüzlendirme; VI, alüminyum oksitle kumlama.
Ergül Ertürk,
Braketler işlem görmüş mine yüzeyine adeziv rezinle yapıştırıldı ve
Dr. Marasal Cakmak Asker Hastanesi,
SBS testi uygulandı. Örnekler artık adeziv indeksi (ARI) kullanılarak
Diş Servisi Protez Bölümü,
Erzurum, Türkiye
incelendi ve kırılma tipleri stereomikroskop kullanarak sayısal olarak
belirlendi. İstatistiksel analiz tek yönlü varyans analizi ve Tukey
karşılaştırma testi ile anlamlılık seviyesi 0.05’de sabitlenerek yapıldı.
Bulgular: V. ve III. gruplar arasında anlamlı fark olmadığı halde, en
yüksek SBS değerleri V. grup için gözlendi. Kumlama grubu (VI.
grup) için SBS değerleri diğer tüm gruplardan anlamlı derecede
düşüktü. 1.,2. ve 4. gruplar genelde mine rezin arayüzeyinde adezivin
%50’sinden azının yüzeyde kalması ile benzer kırılma modları
gösterirken (ARI: 1) (p>0.05), 3.ve 5. gruplar mine rezin arayüzeyinde
yüzeyin %50’sinden fazlasının adezivle kaplı olduğu kırılmaları
gösterdi (ARI: 2).
Sonuç:
Minenin
Er:YAG
lazer
ve
asitle
pürüzlendirme
kombinasyonuyla yüzey tedavisi, tek başına asitle pürüzlendirme
veya lazer irradyasyonundan anlamlı derecede daha yüksek SBS
değerleri ile sonuçlandı. Lazer irradyasyonu hem tek başına hem
Sorumlu Yazar
Fidan Alakus Sabuncuoğlu
de asitle pürüzlendirme kombinasyonuyla, asitle pürüzlendirmeye
geçerli tedavi alternatifleri olarak önerilebilir.
Mareşal Çakmak Asker Hastanesi
Diş Servisi Ortodonti Bölümü, Erzurum,Türkiye
Telefon: 0532 7228904
E-mail: [email protected]
Clin Dent Res 2015: 39(3): 110-117
Anahtar Kelimeler: Er-YAG Lazer, Nd:YAG Lazer, Ortofosforik
Yayın Başvuru Tarihi :24.09.2015
Asit, Makaslama Bağlanma Dayanımı, Kumlama,
Yayına Kabul Tarihi : 04.12.2015
111
CLINICAL DENTISTRY AND RESEARCH
INTRODUCTION
The strength of the bond between the orthodontic bracket
and the enamel surface depends on 3 factors: the bracketbase retention mechanism, the adhesive or bonding resin, and
the preparation of the tooth surface.1 A variety of different
surface treatment methods are available for orthodontic
use.2-9 Orthophosphoric acid etching has been widely used
to prepare tooth enamel for bonding resins and orthodontic
attachments since it was first introduced by Buonocore1 in
1955. Sandblasting, which was introduced in 1940 for cavity
preparation, was later recommended for use in orthodontic
bonding as well.10 More recently, erbium:yttrium-aluminumgarnet (Er:YAG) and neodymium:yttrium-aluminum-garnet
(Nd:YAG) lasers have been proposed as alternatives to
both phosphoric acid etching and sandblasting.8,11,12 The
main advantage of laser etching is that it creates an acidresistant enamel surface with increased resistance to caries
attack.13,14 Moreover, the fractured, uneven surface created
by laser etching of enamel is ideal for adhesion. Adhesive
components are able to penetrate the numerous pores and
small, bubble-like inclusions that result from the melting and
recrystallization of enamel exposed to laser light. Previous
studies have attributed the ability of Er:YAG and Nd:YAG
lasers to effectively ablate enamel and dentine to the high
degree of efficiency with which they absorb both water and
hydroxyapatite.13-15
Although some studies have indicated the bond strength
of acid-etched teeth to be significantly higher than laseretched teeth,15-18 others have demonstrated laser etching
to produce a bond strength comparable or even stronger
than that of acid etching.19,20 Despite this current lack of
consensus regarding what surface conditioning method
will secure optimal bond strength for bonding orthodontic
brackets to dental tissue, there is no study in the literature
comparing the effects of surface conditioning method on
bracket adhesion to enamel. Therefore, this study compared
the effects of different surface treatment methods (acid
etching, laser etching, laser and acid etching in combination,
and sandblasting) on the shear bond strength (SBS) and
fracture mode of orthodontic brackets.
MATERIALS AND METHODS
Specimen Preparation
The study was conducted with 60 extracted human
maxillary first premolars. The teeth were obtained from
orthodontic patients aged between 13 and 20 years of
112
age and were free of caries, restorations and enamel cracks.
Teeth were cleaned by water flushing, disinfected in 0.1
percent (weight/volume) thymol solution to inhibit microbial
growth and transformed to distilled water. Immediately prior
to the experiment, teeth anatomic crowns were transversely
sectioned at the cement-enamel junction of the buccal
aspect using a high-speed grinder (Demco high-speed
grinder; CMP Industries LLC, Albany, NY) under water coolant
and then mounted in self-curing acrylic resin (GC America,
Alsip, Ill). Buccal enamel surfaces were pumiced, washed
and dried before enamel conditioning. A 4x6 mm window
was cut in an acrylic resin plate that was used to limit the
area of enamel to be treated to the exact dimensions of the
orthodontic brackets. This plate also enabled the clinician
to standardize the area to be conditioned in teeth with
different crown lengths. One operator held the acrylic plate
over the tooth surface while a second operator applied
the surface conditioning to the area within the window.
Specimens were randomly divided into six groups (n=10) for
enamel treatment, as follows:
Group I (acid etching): Teeth were etched for 15 s with a
37% orthophosphoric acid gel (ORMCO, USA), rinsed for 15
s, and dried with an oil-free source for 15 s. Acid etching
was observed to produce a frosted white appearance to the
enamel surface.
Group II (Nd:YAG laser irradiation): An Nd:YAG laser device
(2970-nm wavelength; LightWalker, Fotona, Slovenia) with
an output of 1.5W was used in medium-short pulse mode
(MSP; 100 ms, 120 mj, 10 Hz, 1.5 W). The device uses a fiberoptic system to deliver laser energy to a sapphire tip that is
bathed in an adjustable air/water spray. The laser beam was
directed perpendicular to the enamel at a distance of 1 mm
from the tooth surface and applied for 15 s, with air and
water levels set at 90% and 80%, respectively.
Group III (Nd:YAG laser+acid etching): Samples were treated
with Nd:YAG laser irradiation as described above for Group II
followed by acid etching with 37% orthophosphoric acid as
described above for Group I.
Group IV (Er:YAG laser irradiation): An Er:YAG laser device
(2970-nm wavelength; LightWalker, Fotona, Slovenia) with
an output of 1.5 W was used in medium-short pulse mode
(MSP; 100 ms, 120 mj, 10 Hz, 1.5 W). The device uses a fiberoptic system to deliver laser energy to a sapphire tip that is
bathed in an adjustable air/water spray. The laser beam was
directed perpendicular to the enamel at a distance of 1 mm
from the tooth surface and applied for 15 s, with air and
EVALUATION OF SBS AFTER DIFFERENT ENAMEL ETCHING
water levels set at 90% and 80%, respectively.
Group V (Er-YAG laser irradiation+acid etching): Samples
were treated with Er:YAG laser irradiation as described
above for Group IV followed by acid etching with 37%
orthophosphoric acid as described above for Group I.
Group VI (Aluminium oxide sandblasting): Teeth were
sandblasted with a micro-etcher (Micro-Etcher ERC II,
Danville Engineering, San Ramon, California, USA) using
50 μm aluminium oxide particles at 60 psi for 3 seconds.
The sandblasting apparatus was directed perpendicular
to the enamel surface at a distance of 1 mm. Following
sandblasting, samples were washed with water for 20
seconds and air-dried.
Orthodontic Bracket Bonding
Stainless steel brackets (Rocky Mountain Denver, USA) of
approximately the same shape and adhesion area (height
2 mm, base area 3.5x2.0 mm) as those used for maxillary
premolars were used in this study. A bonding agent (Ortho
Solo Sealant, Ormco) was applied to the enamel surfaces
and air-thinned, and adhesive resin (Enlight Light Cure
Adhesive, Ormco) was prepared and applied to enamel
according to the manufacturer’s instructions. Excess resin
was removed with an explorer. Specimens were lightcured for 40 s (Demetron LC, SDS Kerr; light output: 400
mW/cm2 ), stored in deionized water at 37°C for 24 hours,
and thermocycled in water baths between 5°C and 55°C
for 30-second cycles for a total of 500 cycles to simulate
conditions in the oral cavity. Specimens were stored at room
temperature in distilled water for 1 week until SBS testing.
Shear Bond Strength (SBS) Testing
Shear bond strength testing was performed using a universal
testing machine (Shimadzu AG-X, Tokyo, Japan) operated
at a speed of 0.5 mm/min. A knife-edged shearing blade
was secured on the crosshead with the direction of force
parallel to the labial surface and the bracket interface and
struck flush against the edge of the bracket base without
touching the enamel. Values were recorded in Newtons (N)
and converted into megapascals (MPa) by dividing the value
N by the surface area of the bracket base. After debonding,
each specimen was examined under a stereomicroscope
(Olympus SZ61; Olympus Optical Co, Tokyo, Japan) at 10x
magnification to identify the location of bond failure, which
was classified using the Adhesive Remnant Index (ARI), as
follows: 0, no residual adhesive remaining on the enamel; 1,
less than 50% of the adhesive remaining; 2, more than 50%
of the adhesive remaining; 3, all of the adhesive remaining,
with a distinct impression of the bracket base.
Statistical Analysis
Statistical analysis was performed using the Statistical
Package for Social Sciences, Windows v. 10.0.0 (SPSS
Inc., Chicago, Illinois, USA). Descriptive statistics including
means, standard deviations and minimum and maximum
values were calculated for each group. A KolmogorovSmirnov normality test was applied and showed normality
of distribution; thus, one-way analysis of variance (ANOVA)
and post-hoc Tukey tests were used to identify differences
in SBS among groups, and the Fisher Exact χ2 test was
used to evaluate differences in ARI scores between groups,
with the level of significance set at p< 0.05.
RESULTS
Mean SBS values for each group were as follows: I, 9.39±093;
II, 8.78±0.71; III, 13.41±1.63; IV, 8.97±1.02; V, 13.53±1.37; VI,
3.12±0.67 (Table 1). ANOVA showed significant differences
among groups (Table 2; p<0.05). Multiple paired comparisons
(Tukey test) showed no differences between groups III and V
(p= 0.99) and both groups to have significantly higher bond
strengths than the other groups and Group VI (sandblasting) to
have significantly lower bond strengths than the other groups
(p<0.05). No statistically significant difference was observed
between Groups I and II (p: 0.820), Groups I and IV (p: 0.959), or
Groups II and IV (p: 0.999).
The distribution of failure modes as expressed by ARI scores is
given in Table 3. While Group I, II and IV exhibited similar bracket
failure modes, which were mainly failures at the enamel-resin
interface, with less than 50% of the adhesive remaining (ARI:
1), Group III and V showed mainly failures at the enamel-resin
interface, with more than 50% of the adhesive remaining
(ARI: 2). Fisher Exact test results showed that Group VI had
significantly different ARI scores from all other groups (p<
0.001). On the other hand, no significant differences were
observed in ARI scores between Group III and V (p= 1.00),
between Group I and II (p= 0.322), between Group I and IV (p=
0.582), between Group II and III (p= 0.103), and between Group
IV and V (p= 0.024). No enamel fractures were observed in any
of the tested specimens.
In this study, the SEM evaluation of the samples
after debonding showed differences in the surface
characteristics of the teeth in the 6 groups. Scanning
electron photomicrographs of enamel conditioned with
different methods were presented in Figures 1a-f. Figure 1a
shows the enamel surface after phosphoric acid treatment
113
CLINICAL DENTISTRY AND RESEARCH
with regular rough surface and spaces. Dissolution of
hydroxyapatite by phosphoric acid produced tags and
rough surface that afforded the mechanical lock for resin.
The acid-etched sample had a regular and slightly rough
surface, whereas both of the laser samples (Group II and
IV) had irregular and severely rough surfaces (Figure 1b
and c). A honeycomb-like appearance was observed in the
Er:YAG laser-etched group with microcracks on the laser
ablated surfaces, which aid the penetration of resin (Figure
1b). The surfaces treated by Nd:YAG laser showed irregular,
micro porous surfaces and also melting areas could be
observed (Figure1c). The photomicrographs obtained for
group VI showed physical roughness of the enamel surface,
indicating that chemical demineralization did not occur with
sandblasting (Figure 1d). Photomicrograph of the enamel
surface after laser irradiation and then acid treatment
revealed honeycomb-like appearance with more microcracks
than laser alone groups, and the surface destruction
was more prominent (Figure1e, Er:YAG+asit; Figure 1f,
Nd:YAG+asit). Photomicrograph of the enamel surface
after Nd:YAG laser and then acid treatment revealed that
the entire enamel surface was coated with resin, thereby
indicating good enamel-resin bonding (Figure 1f).
DISCUSSION
There is much current research devoted to identifying a viable
alternative to acid etching for the bonding of orthodontic
brackets. One possible solution, laser ablation, has received
conflicting reports.12 Therefore, this study measured the shear
bond strength of specimens after laser irradiation alone and in
combination with acid etching and compared the results with
those of acid etching alone and sandblasting, two other widely
used methods of enamel surface preparation. One drawback of
this study was the low sample size.
The results of this study showed both Nd and Er laser etching
alone (Groups II and IV) produced bond strengths comparable
to those of chemical etching. Although bond strengths of acidetched specimens were higher than those of laser-etched
specimens, the differences were not statistically significant.
These findings concur with those of many studies,11,13,16,19,21-27
but conflict with numerous others.8,17,21,23,28-31 Vissuri et al.13,
Hossain et al.23 and Lee et al.27 reported Er:YAG laser etching
and acid etching to result in similar bond strength. Krishnan et
al.28 found laser etching with 2W/20 Hz and etching with 37%
phosphoric acid to produce similar SBSs. Moreover, the authors
reported all the laser power outputs tested (1.5 W/10 Hz, 1.5
W/20 Hz, 2 W/10 Hz and 2 W/20 Hz) to produce SBSs of levels
114
clinically acceptable for orthodontic bonding, i.e. above 6-8
MPa, the clinically acceptable limits described by Reynolds.29
In contrast, Fraunhofer et al.21 found the shear bond strength
for brackets and Nd:YAG laser-etched enamel to be similar to
that for acid-etched enamel only when the maximum output
of the laser was used, and Usumez et al.8 stated that laser
etching yielded similar but lower and less predictable bond
strengths than acid etching, with bond strengths increasing
with increases in laser power output. The variations in findings
can be attributed to differences in laser type and irradiation
parameters (e.g. wavelength, power output, application
distances, etc.), which affect laser-hard tissue interaction. In
the present study, laser irradiation with 1.5 W/10 Hz Nd:YAG
and Er:YAG lasers alone both yielded bond strengths sufficient
for bonding brackets to enamel.
Among the protocols tested in the present study, Er:YAG laser
followed by acid etching showed the highest bond strength
values. Moreover, the combination of laser and acid etching
produced significantly higher bond strengths than the use
of acid etching alone. The high bond strength of specimens
treated by a combination of laser and acid etching may be
attributed to the laser’s ability to melt and recrystallize the
enamel surface, which is then dissolved by acid etching. To
date, studies on laser etching have addressed various issues,
such as power output, power setting, pulse repetition
rate and application distance. Only one study, conducted
by Türköz and Ulusoy,22 has compared all known enamelconditioning techniques (with the exeption of Nd:YAG). In
that study, specimens irradiated with Er:YAG laser followed
by acid etching had higher SBS values than specimens
treated by acid-etching alone as well as specimens treated
by Er:YAG laser-etching. These findings are in line with
those of the present study. In addition to the higher bond
strength achieved with laser etching, laser etching also
reduces susceptibility to caries attack,14 shortens chair
time8 and is less sensitive to moisture during the etching
process than acid etching.23 Despite these advantages,
laser ethching could cause intrapulpal temperature rise. It
was reported that as long as the heat increase at the pulp
room does not go over the acceptable limits determined by
Zach and Cohen (5.5 0C)32, it would not cause a permanent
damage in the pulp. Although intrapulpal temperature rise
was not measured in the present study, laser system was
used under water-cooling and only for a short time.
With the exception of sandblasting, all methods tested had
bond strengths values considered to be clinically acceptable
(5.9-7.8 MPa) according to Reynolds.29 The low SBS value for
EVALUATION OF SBS AFTER DIFFERENT ENAMEL ETCHING
Table 1. Mean bond strength values (MPa) and descriptive statistics
SBS (MPa)
n
Mean ±Std.
Dev.
Median
Group I
10
9.39 ±093
Group II
10
Group III
95% Confidence Interval for Mean
Lower Bound
Upper Bound
Min.
(MPa)
Max.
(MPa)
9.06
8.72
10.06
8.01
11.06
8.78 ±0.71
8.42
8.26
9.29
8.03
10.16
10
13.41 ±1.63
13.05
12.24
14.58
10.88
15.89
Group IV
10
8.97 ±1.02
8.43
8.24
9.71
8.01
11.16
Group V
10
13.53 ±1.37
13.24
12.55
14.51
11.54
15.70
Group VI
10
3.12 ±0.67
2.89
2.64
3.60
2.12
3.92
Table 2. Multiple comparison testing for groups.
Groups
Group I
Group II
Group III
Group IV
Group V
Group VI
Group I
-
NS(0.82)
*
NS(0.95)
*
*
Group II
NS(0.82)
-
*
NS(0.99)
*
*
Group III
*
*
-
*
NS(0.99)
*
Group IV
NS(0.95)
NS(0.99)
*
-
*
*
Group V
*
*
NS(0.99)
*
-
*
Group VI
*
*
*
*
*
-
*The mean difference is significant at the 0.05 level. NS: Not significant.
Table 3. The distribution of failure modes as expressed by ARI scores is given in percentage in Table 3 (Fisher Exact test χ2: 66,43 p<0.001.)
Groups
0
1
2
3
χ2
Group I
2(%20)
7(%70)
1(%10)
0
9.95a
Group II
0
7(%70)
3(%30)
0
16.5b
Group III
0
2(%20)
6(%60)
2(%20)
17.33c
Group IV
0
8(%80)
2(%20)
0
16.44d
Group V
0
2(%20)
5(%50)
3(%30)
17.33e
Group VI
9(%90)
1(%10)
0
0
p
p<0.001
a, χ2 value for the comparison of Group I and VI; b, χ2 value for the comparison of Group II and VI; c, χ2 value for the comparison of Group III
and VI; d, χ2 value for the comparison of Group IV and VI; e, χ2 value for the comparison of Group V and VI.
the sandblasting group (3.12±0.67 MPa) is consistent with
other studies evaluating the use of sandblasting for enamel
conditioning10,33,34 and indicates sandblasting to be the only
form of macro-etching33 insufficient for bonding orthodontic
brackets to enamel. A further disadvantage of sandblasting is
that the aerosol used contains aluminium oxide that may be
swallowed or inhaled by the patient or doctor.
In addition to the type of surface preparation used, the strength
of the bond between dental tissue and orthodontic brackets
may vary according to the intensity and quality of light, curing
time, distance and orientation of the light tip used for adhesive
curing, composite type, thickness of resin increments and
presence of remnant adhesive.35,36 In the present study, all teeth
were freshly extracted human maxillary first premolars. Prior to
etching, a window with the same dimensions as the orthodontic
brackets used (4x6 mm) was cut in an acrylic resin plate, which
was then used as a template to limit the area of enamel
subjected to surface conditioning. The acid-etching procedure
115
CLINICAL DENTISTRY AND RESEARCH
with a combination of laser and acid-etching results in a
significantly higher shear bond strength than acid etching or
laser irradiation alone; thus, this study recommends the use
of either laser irradiation in combination with acid-etching
or laser irradiation alone as a viable treatment alternative to
acid-etching. Moreover, sandblasting should not be used for
enamel etching because the resultant bond is insufficient.
REFERENCES
Figure 1: 1a:SEM image of phosphoric-acid etched enamel surface.
1b: SEM image of enamel irradiated with Er:YAG laser 1c: SEM image of
enamel irradiated with Nd:YAG laser 1d: SEM image of enamel surface
after sandblasting. 1e: SEM image of enamel irradiated with Er:YAG
laser with orthophosphoric acid. 1f: SEM image of enamel irradiated
with Nd:YAG laser with orthophosphoric acid.
1. Urabe H, Rossouw PE, Titley KC, Yamin C. Combinations of etchants,
composite resins, and bracket systems: an important choice in
orthodontic bonding procedures. Angle Orthod 1999; 69: 267-275.
2. Büyükyılmaz T , Zachrisson YØ , Zachrisson BU. Improving
orthodontic bonding to gold alloy. Am J Orthod Dentofacial Orthop
1995; 108: 510-518.
3. Wigdor HA, Walsh JT, Featherstone JDB, Visuri SR, Fried D, Waldvogel
JL. Lasers in dentistry. Lasers Surg Med 1995; 16: 103-108.
was completed in 45 seconds: 15 seconds for enamel-etching
with phosphoric acid, which has been reported to be adequate
for orthodontic bonding;37 15 seconds of water spraying; and
15 seconds of air-drying. Laser etching was performed using
either an Er:YAG or Nd:YAG laser system with low-power (1.5
W) output, since higher levels of power and longer irradiation
times may have irreversible, detrimental effects on tooth pulp.38
Factors related to polymerization were controlled for by using
the same curing unit and curing time (10 seconds for the mesial,
distal, occlusal and gingival sides of each tooth, for a total of
40 seconds per tooth), and all brackets were adhered to the
samples with the same adhesive by the same investigator using
firm pressure to ensure uniform adhesive thickness. Finally, all
samples were tested for SBS using the same universal testing
machine (Shimadzu AG-X) to apply uniform shear forces at a
crosshead speed of 0.5mm/minute.
The present study found no significant differences in
ARI values among the groups with the exception of the
sandblasting group (P<0.001). In this group, all teeth had
ARI scores of 0, indicating bond failure between the tooth
surface and the adhesive. In all other groups, bond failure
occurred mainly between the bracket base and the adhesive
surface. Larger amounts of residual adhesive were found on
tooth surfaces in Groups III (Nd:YAG laser +acid) and V (Er:YAG
laser+acid), reflecting higher SBS values in teeth treated with a
combination of laser irradiation and acid etching.
CONCLUSION
Within the limitations of this in vitro study, the findings of
the current study indicate that enamel surface treatment
116
4. Miller S, Zernik JH. Sandblasting of bands to increase bond
strength. J Clin Orthod 1996; 30: 217-222.
5. Millett DT, McCabe JF, Bennett TG, Carter NE, Gordon PH. The
effect of sandblasting on retention of first molars orthodontic bands
cemented with glass ionomer cement. Br J Orthod 1995; 22: 161-169.
6. Chung KH, Hwang YC. Bonding strengths of porcelain repair
systems with various surface treatments. J Prosthet Dent 1997;
78: 267-274.
7. Takeda FH, Harashima T, Eto JN, Kimura Y, Matsumoto K. Effect
of Er:YAG laser treatment on the root canal walls of human teeth: a
SEM study. Endod Dent Traumatol 1998; 14: 270-273.
8. Üşümez S, Orhan M, Üşümez A. Laser etching of enamel for
direct bonding with an Er,Cr:YSGG hydrokinetic laser system. Am J
Orthod Dentofacial Orthop 2002; 122: 649-656.
9. Buonocore MG. A simple method of increasing the adhesion of
acrylic filling materials to enamel surfaces. J Dent Res 1955; 34:
849–853.
10. Olsen ME, Bishara SE, Damon P, Jakobsen JR. Comparison of
shear bond strength and surface structure between conventional
acid etching and air abrasion of human enamel. Am J Orthod
Dentofacial Orthop 1997; 112: 502-506.
11. Ozer T, Basaran G, Berk N. Laser etching of enamel for
orthodontic bonding. Am J Orthod Dentofacial Orthop 2008; 134:
193–197.
12. Basaran G, Ozer T, Berk N, Hamamci O. Etching enamel for
orthodontics with an erbium, chromium:yttriumscandium- galliumgarnet laser system. Angle Orthod 2007; 77: 117–123.
EVALUATION OF SBS AFTER DIFFERENT ENAMEL ETCHING
13. Visuri SR, Gilbert JL, Wright DD, Wigdor HA, Walsh JT Jr. Shear
strengths of composite bonded to Er:YAG laser prepared dentin. J
Dent Res 1996; 75: 599–605.
14. Klein AL, Rodrigues LK, Eduardo CP, Nobre dos Santos M,
Cury JA. Caries inhibition around composite restorations by pulsed
carbon dioxide laser application. Eur J Oral Sci 2005; 113: 239–244.
15. Von Fraunhofer JA, Allen DJ, Orbell GM. Laser etching of enamel
for direct bonding. Angle Orthod 1993; 63: 73-76.
16. Ariyaratnam MT, Wilson MA, Mackie IC, Blinkhorn AS. A
comparisonof surface roughness and composite/enamel bond
strength of human enamel following the application of the Nd:YAG
laserand etching with phosphoric acid. Dent Mater 1997; 13: 51–55.
17. Drummond JL, Wigdor HA, Walsh JT, Fadavi S, Punwani I. Sealant
bond strengths of CO2 laser-etched vs acid-etched bovine enamel.
Lasers Surg Med 2000; 27: 111–118.
18. Corpas-Pastor L, Moreno JV, Garrido JDDLG, Muriel VP, MooreK,
Elias A. Comparing the tensile strength of brackets adhered to
laser-etched enamel vs acid-etched enamel. J Am Dent Assoc
1997; 128: 732–737.
27. Hossain M, Nakamura Y, Tamaki Y, Yamada Y, Murakami Y,
Matsumoto K. Atomic analysis and knoop hardness measurement
of the cavity floor prepared by Er,Cr:YSGG laser irradiation in vitro. J
Oral Rehabil 2003; 30: 515-521.
28. KV Krishnan, N Kurunji Kumaran, Vidyaa Hari Iyer, K
Rajasigamani. Laser Etched vs Conventional Etched Enamel: Effect
on. Shear Bond Strength of Orthodontic Brackets. Int J Laser Dent
2013; 3: 1-6.
29. Reynolds IR. A review of direct orthodontic bonding. Br J
Orthod 1975; 2: 171-180.
30. Roberts-Harry DP. Laser etching of teeth for orthodontic
bracket placement: a preliminary clinical study. Lasers Surg Med
1992; 12: 467–470.
31. Corpas-Pastor L, Moreno JV, Garrido JDDLG, Muriel VP, Moore
K, Elias A. Comparing the tensile strength of brackets adhered
to laser-etched enamel vs acid-etched enamel. J Am Dent Assoc
1997; 128: 732–737.
32. Zach L, Cohen G. Pulp response to externally applied heat. Oral
Surg Oral Med Oral Path 1965; 19: 515-530.
19. Walsh LJ, Abood D, Brockhurst PJ. Bonding of composite resin
to carbon dioxide laser-etched human enamel. Dent Mater 1994;
10: 162–166.
33. Reisner KR, Levitt HL, Mante F. Enamel preparation between
the use of a sandblaster and current techniques. Am J Orthod
Dentofacial Orthop 1997; 111: 366-373.
20. Melendez EJ, Arcoria CJ, Dewald JP, Wagner MJ. Effect of
laseretch on bond strengths of glass ionomers. J Prosthet Dent
1992; 67: 307–312.
34. Canay S, Kocadereli I, Akça E. The effect of enamel air abrasion
on the retention of bonded metallic orthodontic brackets. Am J
Orthod Dentofacial Orthop 2000; 117: 15-19.
21. Fraunhofer JA, Allen DJ, Orbell GM. Laser etching of direct
bonding. Angle Orthod 1992; 63: 73-76.
35. Caldas DBM, Almeida JB, Correr Sobrinho L, Sinhoreti MAC,
Consani S. Influence of curing tip distance on resin composite
Knoop hardness number, using three different light curing units.
Open Dent 2003; 28: 315-320.
22. Türköz C, Ulusoy C. Evaluation of different enamel conditioning
techniques for orthodontic bonding. Korean J Orthod 2012; 42: 32-38.
23. Lee BS, Hsieh TT, Lee YL, Lan WH, Hsu YJ, Wen PH et al. Bond
strengths of orthodontic bracket after acid-etched, Er:YAG laserirradiated and combined treatment on enamel surface. Angle
Orthod 2003; 73: 565-570.
24. Liberman R, Segal TH, Nordenberg D, Serebro LI. Adhesion of
composite materials to enamel: comparison between the use of acid
and lasing as pretreatment. Lasers Surg Med 1984; 4: 323– 327.
25. Shahabi S, Brockhurst PJ, Walsh LJ. Effect of tooth-related
factors on the shear bond strengths obtained with CO2 laser
conditioning of enamel. Aust Dent J 1997; 42: 81–84.
36. Aquiar FH, Lazzari CR, Lima DA, Ambrosano GM, Lovadino JR.
Effect of light curing tip distance and resin shade on microhardness
of hybrid resin composite. Brazil Oral Res 2005; 19: 302-306.
37. Osorio R, Toledano M, Garcia-Godoy F. Bracket bonding with
15 -of 60- seconds etching and adhesive remnant on enamel after
debonding. Angle Orthod 1999; 69: 45-49.
38. Obato A. Effectivenes of CO2 laser irridation on ceramic bracket
debonding. Nihon Kyosei Shika Gakkai Zasshi 1995; 54: 285-295.
26. Whitters CJ, Strang R. Preliminary investigation of a novel
carbon dioxide laser for applications in dentistry. Lasers Surg Med
2000; 26: 262–269.
117