Article_6_2_3-1

DENTAL MATERIALS

Original Articles
EFFECTS OF ETCHING MODE ON BOND STRENGTH OF UNIVERSAL
ADHESIVES
Andre Figueiredo Reis1a*, Paula Maria Mendes Alves2b, Rose Yakushijin Kumagai2c

1
Department of Restorative Dental Sciences, Division of Operative Dentistry, College of Dentistry
University of Florida, Gainesville, FL, USA
2
Department of Restorative Dentistry, Dentistry Clinic, Guarulhos University, Guarulhos, SP, Brazil

a
DDS, MS, PhD, Clinical Associate Professor
b
DDS, Master student
c
DDS, MS, PhD student

ABSTRACT DOI: https://doi.org/10.25241/stomaeduj.2019.6(2).art.3

Introduction: The aim of this study was to analyze the bond strength to dentin produced OPEN ACCESS This is
an Open Access article under
by new universal adhesive systems used in self-etch and etch-and rinse application the CC BY-NC 4.0 license.

modes. Peer-Reviewed
Materials and Methods: Sixty human teeth were divided into 6 groups according to Article

the different universal adhesive systems: Scotchbond Universal (SBU - 3M ESPE), Clearfil Citation: Reis AF, Alves PMM,
Kumagai RY. Effects of etching
Universal (CFU - Kuraray), Futurabond U (FBU - VOCO) Xeno Select (XS - Dentsply De mode on bond strength of universal
Trey), Prime&Bond Elect (PBE – Dentsply Caulk) and All Bond Universal (ABU, Bisco). Then, adhesives.
Stoma Edu J. 2019;6(2):111-117
the teeth were subdivided into 2 subgroups, according to the application mode: etch-
Received: March 19, 2019
and-rinse or self-etch. Composite crowns were built after application of the adhesive Revised: April 16, 2019
systems and the restored teeth were sectioned in both “X” and “Y” directions into sticks Accepted: May 10, 2019
Published: May 15, 2019
with a cross-sectional bonded area of approximately 1 mm2. The microtensile test was
*Corresponding author:
carried on a universal testing machine operated at a crosshead speed of 1 mm/min. Andre Figueiredo Reis, DDS, MS, PhD,
Bond strength values were statistically evaluated using two-way ANOVA and the Tukey Clinical Associate Professor,
Department of Restorative Dental
post-hoc test. Sciences, Division of Operative
Dentistry, University of Florida,1395
Results: SBU, XS and ABU presented significantly higher bond strength values when Center Drive, Room D9-6, P.O. Box
applied on the etch-and-rinse mode (p < 0.05). CFU, FBU and PBE presented no significant 100415, Gainesville, FL 32610-
0415, USA
difference in bond strength values between etch-and-rinse and self-etching groups (p > Phone: +1(352)273-5850;
Fax: +1(352)846-1643;
0.05). e-mail: AReis@dental.ufl.edu
Conclusion: The adhesive performance of Universal Adhesives was similar or higher Copyright: © 2019
when they were used in the etch-and-rinse mode in comparison with the self-etching the Editorial Council for the
Stomatology Edu Journal.
mode.
Keywords: Acid etching; Dental; Bond strength; Dental bonding; Universal adhesives.

1. Introduction versions of their multiple-step precursors, and have
Bonding to enamel and dentin is mainly been recently combined and marketed as Universal
accomplished by micromechanical interlocking adhesives [7,8]. These multimodal adhesives may
between synthetic, naturally degradable polymers, be used in etch-and-rinse mode, self-etch mode or
and enamel or dentin collagen fibrils [1]. Effective, selective-etch mode, depending on the clinician’s
long-lasting bonding to dentin has been a challenge preference [9,10].
to dental clinicians, because in order to promote Although recent studies reported that universal
adhesion to dentin, the mineral phase needs to be adhesives applied using either the etch-and-
totally or partially removed, and substituted by an rinse or the self-etch mode produce excellent
adhesive solution, that will permeate this collagen- immediate bond strength to bonding substrates
rich layer, and polymerize in situ, forming what has [11], limited information is available on the newest
been called the hybrid layer [1-3]. universal adhesives recently introduced by different
Different approaches, with different numbers of manufacturers. Thus, the aim of this study was to
steps and degrees of sensitivity have been used to evaluate the bond strength to dentin produced by
bond resin-based materials to enamel and dentin six universal adhesives applied either on the etch-
[4-6]. Efforts have been directed to reduce the and-rinse or self-etching mode. The tested null
number of steps and technique sensitivity. One- hypothesis was that there is no difference in bond
bottle self-priming etch-and-rinse systems, as well strength produced by universal adhesives applied
as single-step self-etching adhesives are simplified on the etch-and-rinse or self-etching mode.

Stomatology Edu Journal 111
EFFECTS OF ETCHING MODE ON BOND STRENGTH OF UNIVERSAL
ADHESIVES

Original Articles Table 1. Universal adhesives short name, manufacturer, pH, composition,
and application instructions.

Adhesive, pH Composition Self-Etch Etch-and-Rinse
(Batch Number)
Scotchbond 2-HEMA, 10-MDP, 1. Apply the adhesive to the 1. Apply etchant for 15 s
Universal (SBU) dimethacrylate resins, prepared tooth and rub in 2. Rinse for 10 s
3M Espe, St VitrebondTM copolymer, for 20 s 3. Air dry 2 s
Paul, MN, USA 2.7 silane, filler, ethanol, water, 2. Gently air-dry the 4. Apply adhesive as for
(554836) iniciators adhesive for 5 s for the sol- the self-etch mode
vent to evaporate
3. Light cure for 10 s
Clearfil HEMA, MDP, Bis-GMA, 1. Apply bond and rub for 1. Apply etchant for 10 s
Universal Bond ethanol, camphorquinone, 20 s or 40 s 2. Rinse thoroughly
(CFU) hydrophilic aliphatic dimeth- 2. Dry by blowing mild air 3. Dry
Kuraray, Tokyo, 2.3 acrylate, for 5 s 4. Apply adhesive as for
Japan (C40001) silane coupling agent, 3. Light cure for 10 s the self-etch mode
colloidal silica, water, and
accelerators
Futurabond U 2-HEMA, Bis-GMA, HEMA, 1. Activate single dose 1. Apply etchant for 15 s
(FBU) acidic adhesive monomer, adhesive package 2. Rinse for 10 s
VOCO, urethane dimethacrylate, 2. Apply adhesive to the 3. Air dry 2 s
Cuxhaven, catalyst, silica nanoparticles, cavity surface using the 4. Apply adhesive as for
Germany ethanol Voco Single Tim brush and the self-etch mode
(1333352) 2.3 rub adhesive in for 20 s
3. Dry adhesive with dry,
oil-free air for at least 5 s
4. Light cure for 10 s
Xeno Select Bifunctional acryl resin with 1. Apply the adhesive to the 1. Apply etchant for 15 s
(XS) amide functions, prepared tooth and rub in 2. Rinse for 10 s
Dentsply De Acryloylamino alkylsulfonic for 20s 3. Air dry 2 s
Trey, Konstanz, acid, “inverse” 2. Gently air-dry the 4. Apply adhesive as for
Germany functionalized phosphoric adhesive for 5 s for the the self-etch mode
(1402000636) 1.3 acid ester, Camphorquinone, solvent to evaporate
Coinitiator, Butylated 3. Light cure for 10 s
benzenediol, Water,
tert-Butanol
Prime&Bond Mono-, di- and trimethacry- 1. Apply generous amounts 1. Condition enamel for
Elect (PBE) late resins, PENTA, diketone; of adhesives to thoroughly at least 15 seconds and
Dentsply Caulk, organic phosphine oxide, wet all tooth surfaces dentin for 15 seconds
Milford, DE, USA cetylamine hydrofluoride, 2. Agitate applied adhesive or less.
acetone, water, self-cure for 20 s. Re-apply to coat 2. Rinse for 15 s
(141008) 2.5 activator preparation for the entire 3. Dry
20 s period 4. Apply adhesive as for
3. Remove excess solvent the self-etch mode
by gentle dryingwith clean,
dry air for at least 5 s
4. Light cure for 10 s
All Bond Univer- 2-HEMA, 10-MDP, Bis-GMA, 1. Apply two separate coats 2. Rinse thoroughly
sal (1300006652) ethanol, water, initiators of adhesive with agitation 3. Remove excess water
for 10-15 s per coat by blotting surface with
2. Evaporate solvent by an absorbent pellet or
thorough air-drying for high volume evacuation
least 10 s. for 1-2 s, leaving the
No visible movement of preparation visibly moist
3.2 adhesive 4. Apply adhesive as for
3. Surface should have a the self-etch mode
uniform glossy appearance.
If not, repeat steps 1 and 2
4. Light cure for 10 s
Abbreviations: 2-HEMA, 2-hydroxyethyl methacrylate; 10-MDP, 10-methacryloyloxydecyl dihydrogen phosphate; Bis-GMA, bisphenol
A glycidyl methacrylate; PENTA, dipentaerythritol penta acrylate monophosphate.

112 Stoma Edu J. 2019;6(2): 111-117 http://www.stomaeduj.com
EFFECTS OF ETCHING MODE ON BOND STRENGTH OF UNIVERSAL
ADHESIVES

Original Articles
2. Materials and Methods a magnification of 50X (PanTec, Panambra Ind. e
Sixty freshly extracted human third molars were Tecnica SA, Sao Paulo, Brazil). Failure was classified
used. The teeth were obtained following an approved according to one of four types: cohesive failure in
protocol by the review board of the University of dentin, adhesive failure at the adhesive-dentine
Guarulhos (# 641.271). After disinfection and removal interface, cohesive failure in resin composite or
of soft tissues, the ﬂat coronal dentin surfaces were mixed failure.
exposed using 600-grit SiC paper under running
water to create a standardized smear layer. 3. Results
The teeth were randomly assigned to six experimental The mean bond strength values and standard
groups, which were restored using six commercially deviation for the different groups are are shown in
available universal adhesive systems: Clearfil Table 2. The two-way ANOVA revealed that there
Universal (Kuraray), Scotchbond Universal (3M Espe), were statistically significant differences for the factor
Futurabond U (Voco), Prime&Bond Elect (Dentsply “universal adhesive” (p < 0.00021) and for the factor
Caulk), All Bond Universal (Bisco) and Xeno Select “etching mode” (p = 0.00001). In addition, it identified
(Dentsply De Trey). The composition, batch number a significant interaction between the two factors (p =
and application instructions are listed in Table 1. The 0.00157). The Tukey post-hoc test showed significant
sixty teeth were randomly assigned to 6 test groups, differences among adhesive systems for the different
according to the universal adhesives used, and etching modes (p < 0.05).
then subdivided into 2 subgroups according to the Scotchbond Universal, Xeno Select and All Bond
application mode: etch-and-rinse or self-etching (n Universal presented significantly higher bond
= 5). For the etch-and-rinse groups, 35% phosphoric strength values when applied on the etch-and-rinse
acid was applied for 15 s, thoroughly rinsed with mode (p < 0.05). Clearfil Universal, Futurabond U
water, and excess water was removed with cotton and Prime&Bond Elect presented no significant
pellets. Care was taken not to dehydrate dentin difference in bond strength values between the
surfaces prior to adhesive application. For the self- etch-and-rinse and self-etchnig groups (p > 0.05).
etching groups, the dentin surface was dried with an When the etch-and-rinse mode was used,
air stream prior to the adhesive application. Scotchbond Universal and Xeno Select presented the
After application of the adhesive resins according to highest µTBS values, with no significant difference
the manufacturers’ instructions, composite crowns between them (p > 0.05). However, Xeno Select was
of 5 mm in height were built up incrementally with not significantly different from the other groups (p >
composite resin (TPH3, Shade A3, Dentsply Caulk, 0.05). For the self-ecthing mode groups, the highest
Milford, DE, USA). A LED light-curing unit (Radii Plus - µTBS values were presented by Futurabond U and
SDI, Victoria, Australia) with a power output of 1,500 Scotchbond Universal, with no significant difference
mW/cm2 was used to polymerize all specimens. Each between them (p > 0.05). However, Scotchbond
increment (not exceeding 2 mm thickness) was light Universal was not significantly different from the
cured for 20 seconds. The restored teeth were stored other Universal Adhesives when used in self-etching
in distilled water at 37oC for 24 hours. mode (p > 0.05).
Afterwards, the restored teeth were serially Fig. 1 shows the distribution of fracture patterns
sectioned perpendicularly to the adhesive-tooth for the different groups. The failure mode analysis
interface into slabs, and the slabs into beams with revealed that the majority of failures were adhesive
a cross-sectional bonded area of approximately 1 at the adhesive-dentin interface for most groups,
mm2 using a diamond saw (Isomet 1000; Buehler, except for Scotchbond Universal and All Bond
Lake Bluff, IL, USA). Beams were fixed to the grips of Universal applied on the etch-and-rinse mode,
a universal testing machine (EZ Test; Shimadzu Corp, which presented a high number of cohesive failures
Kyoto, Japan) using a cyanoacrylate adhesive (Loctite in resin composite.
Super Bonder Gel; Henkel, Düsseldorf, Germany) and
tested in tension at a crosshead speed of 1 mm/ 4. Discussion
min until fracture occurred. The maximum tensile Recently, a new type of single-step self-etching
load was divided by specimen cross-sectional area, adhesive has been introduced. This type of self-
measured with a digital caliper (Mitutoyo Co., Tokyo, etching adhesive is categorized as “universal” or
Japan), to express results in units of stress (MPa). Five “multi-mode” as it can be used either with the
beams were selected from each restored tooth, and etch-and-rinse or the self-etching approaches [12-
the average value for each tooth was used in the 15]. Therefore, universal adhesives are used with
calculations. Bond strength values were statistically phosphoric acid pre-etching in the etch-and-rinse
evaluated using a two-way ANOVA and the Tukey or selective-etch approaches, which enhances bond
post-hoc test at a preset signiﬁcance level of 0.05. strength to enamel. In addition, it also provides a
Statistical analyses were performed using a personal simplified self-etching approach for dentin substrate
computer program (SAS V9, SAS Institute, Cary, NC). [16]. However, this type of adhesive has only recently
Failure modes were determined by visual examination been introduced to the market, and there is little
of fractured specimens in a stereomicroscope at information as to whether the different etching

Stomatology Edu Journal 113
EFFECTS OF ETCHING MODE ON BOND STRENGTH OF UNIVERSAL
ADHESIVES

Original Articles Table 2. Mean bond strength values in MPa (SD) produced by the universal adhesives applied in self-etching
and etch-and-rinse modes.

Universal Adhesives Etch-and-Rinse Self-etching
Scotchbond Universal 96.8 (14.9) Aa 47.5 (17.6) ABb
Clearfil Universal 52.2 (11.1) Ba 36.6 (13.0) Ba
Futurabond U 63.7 (14.4) Ba 67.5 (5.3) Aa
Xeno Select 76.1 (31.5) ABa 40.4 (10.7) Bb
Prime&Bond Elect 56.0 (8.4) Ba 40.7 (7.2) Ba
All Bond Universal 65.0 (7.1) Ba 27.6 (4.2) Bb
Means followed by different letters (lower case – row, upper case – column) differ among them by Tukey test at 95% confidence level.

Figure 1. Distribution of failure modes for the different groups.

modes achieve equivalent bonding performance to the components in these materials are similar, there
dentin. Our null hypothesis was rejected, because may be differences in the quantities and proportions
for three of the tested universal adhesives, bond of water, solvent, MDP, and dimethacrylate resins
strength was significantly higher when the etch- among the adhesives. There is a possibility that such
and-rinse approach was used. differences may influence viscosity and wettability
The resin composition as well as the presence and of each bonding agent, affecting the ability of resin
type of fillers might play important roles in bonding monomers to penetrate into decalcified dentin [16].
effectiveness [17]. Each self-etch adhesive contains When used in the self-etching mode, these three
its specific functional monomer that, to a large MDP-containing universal adhesives presented
extent, determines its actual adhesive performance bond strength values that were not significantly
[18]. The specific molecular formula of the functional different from each other. However, when used on
monomer and the dissolution rate of its calcium the etch-and-rinse mode, Scotchbond Universal
salt are thought to influence bonding performance. presented significantly higher bond strengths.
The potential to chemically interact with interfacial More than a decade ago, when single step self-
hydroxyapatite might be helpful in the adhesion etching adhesives were first introduced to the market,
process. This interaction occurs with mild self- they were not recommended for use in the etch-and-
etching adhesives that partially demineralize rinse mode, because lower bonding performance
the dentin surface. It has been shown that MDP to dentin was observed when phosphoric acid
(10-methacryloxydecyl dihydrogen phosphate) is was used prior to adhesive application [4,19,20]. In
effective in bonding to hydroxyapatite, and seems to the present investigation the immediate adhesive
be very stable. Three of the tested adhesives (Clearfil performance of the recently introduced universal
Universal, Scotchbond Universal and All Bond adhesives was always significantly higher or not
Universal) present MDP as functional monomer. While significantly different when used in the etch-and-

114 Stoma Edu J. 2019;6(2): 111-117 http://www.stomaeduj.com
EFFECTS OF ETCHING MODE ON BOND STRENGTH OF UNIVERSAL
ADHESIVES

Original Articles
rinse mode. Demonstrating that adjustments in the performance of universal adhesives, Zhang et al. [10]
chemical formulation of single-step self-etching and Chen et al. [21] reported remarkable decrease
adhesives was made so they can also be used in in bond strengths and nanoleakage with signs of
the etch-and-rinse mode. It seems that the problem water-treeing on resin dentin interfaces produced
of the bonding mode incompatibility has been with Futurabond U [21,10]. In fact, all universal
solved by manufacturers through blending less adhesives tested in the above-mentioned study of
acidic resin monomers in the appropriately reduced Zhang et al. [10], with the exception or Prime&Bond
concentrations with other resin monomers [21]. Elect and Scotchbond Universal (applied in self-
Three of the tested adhesives (Scotchbond Universal, etching mode), presented significant reduction
Xeno Select and All Bond Universal) presented in bond strengths after 12 months of storage.
significantly lower bond strength values when used in Previous investigations are in accordance with the
the self-etching mode, in comparison with the etch- present study, which demonstrated similar or higher
and-rinse groups. This reduction probably occurs performance, clinically or in vitro, when universal
due to the higher pH of these adhesives, classified adhesives are applied in the etch-and-rinse mode
as ultra-mild systems, in comparison with the other [12,13,24]. Even though the hybrid layer thickness
products. The interaction depth with dentin depends is approximately 10 times thicker when used in the
on the pH of the adhesives [21]. Depending on the etch-and-rinse mode (≈ 5 µm) in comparison with
pH, self-etch adhesives may be classified into ultra- the self-etching approach (≈ 0.5 µm), thicker hybrid
mild (pH > 2.5, 0.2–0.5 µm interaction depth), mild layers formed in dentin substrates have been shown
(pH ≈ 2; 0.5–1 µm interaction depth), intermediate not to necessarily produce higher bond strengths
(pH, 1–2; 1–2 µm interaction depth), and strong (pH [25].
< 1, > 5 µm interaction depth, similar to etching with
phosphoric acid) [22]. More aggressive self-etching 5. Conclusion
systems present higher contents of acidic monomers According to the results of the present investigation,
and water, resulting in increased hydrophilicity, the immediate bonding performance of Universal
which will result in increased water sorption, and Adhesives was similar or higher when they were
consequently, decreased hydrolytic stability [4]. In used in the etch-and-rinse mode in comparison with
addition, continued etching along the base of hybrid the self-etching mode.
layers after polymerization of those adhesives can
occur [23]. Among the products tested, All Bond Author Contributions
Universal presents the highest pH, 3.2. Even though AR: participated in the study design, statistical analy.
not significantly different, it also presented the lowest PA and RK: participated in the microtensile bond
bond strength values when used in the self-etching strength test, and manuscript writing. sis and
mode. On a study by Chen et al. [21], TEM observations manuscript writing.
revealed that All Bond Universal presented the
shallowest interaction with dentin when used in the Acknowledgments
self-etching mode, approximately 0.2 µm. On the There is no conflict of interest for any of the authors
other hand, when used in the self-etching mode, of the paper. This research did not receive any
Futurabond U presented the highest bond strength specific grant from funding agencies in the public,
values. However, in recent reports on the long-term commercial, or not for-profit sectors.

References
1. Nakabayashi N, Kojima K, Masuhara E. The promotion of nano leakage patterns in resin-dentin interfaces produced by
adhesion by the infiltration of monomers into tooth substrates. J different bonding strategies. Dent Mater.
Biomed Mater Res. 1982;16(3):265-273. 2007;23(9):1164-1172.
[CrossRef ] [PubMed] Google Scholar Scopus [CrossRef ] Google Scholar
2. Hashimoto M, Ohno H, Kaga M, et al. In vivo degradation 7. Perdigão J, Sezinando A, Monteiro PC. Laboratory bonding ability
of resin-dentin bonds in humans over 1 to 3 years. J Dent Res. of a multipurpose dentin adhesive. Am J Dent. 2012;25(3):153-158.
2000;79(6):1385-1391. [PubMed] Google Scholar Scopus
[Full text links] [CrossRef ] [PubMed] Google Scholar Scopus 8. Makishi P, André CB, Ayres APA, et al. Effect of storage time on
3. Sano H, Yoshikawa T, Pereira PNR, et al. Long-term durability of bond strength and nanoleakage expression of universal adhesives
dentin bonds made with a self-etching primer, in vivo. J Dent Res. bonded to dentin and etched enamel. Oper Dent. 41(3):305-317.
1999;78(4):906-911. [Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
[Full text links] [CrossRef ] [PubMed] Google Scholar Scopus 9. Rosa WLO, Piva E, Silva AF. Bond strength of universal adhesives:
4. Nagarkar S, Theis-Mahon N, Perdigão J. Universal A systematic review and meta-analysis. J Dent. 2015;43(7):765-
dental adhesives: Current status, laboratory testing, and 776.
clinical performance. J Biomed Mater Res B Appl Biomater. [Full text links] [PubMed] Google Scholar Scopus
2019;107(6):2121-2131. 10. Zhang Z, Tian F, Niu L, et al. Defying ageing: An expectation for
[Full text links] [CrossRef ] [PubMed] Google Scholar Scopus dentine bonding with universal adhesives? J Dent. 2016;45:43-52.
5. Feitosa VP, Sauro S, Zenobi W, et al. Degradation of adhesive- [Full text links] [CrossRef ] [PubMed] Google Scholar
dentin interfaces created using different bonding strategies after 11. Hanabusa M, Mine A, Kuboki T, et al. Bonding effectiveness
five-year simulated pulpal pressure. J Adhes Dent. 2019;21(3):199- of a new ‘multi-mode’ adhesive to enamel and dentine. J Dent.
207. 2012;40(6):475-484.
[Full text links] [PubMed] Google Scholar Scopus [Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
6. Reis AF, Giannini M, Pereira PN. Long-term TEM analysis of the 12. Muñoz MA, Luque I, Hass V, et al. Immediate bonding properties

Stomatology Edu Journal 115
EFFECTS OF ETCHING MODE ON BOND STRENGTH OF UNIVERSAL
ADHESIVES

Original Articles of universal adhesives to dentine. J Dent. 2013;41(5):404-411.
[Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
13. Wagner A, Wendler M, Petschelt A, et al. Bonding performance
[Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
19. Van Landuyt KL, Peumans M, De Munck J, et al. Extension of
a one-step self-etch adhesive into a multi-step adhesive. Dent
of universal adhesives in different etching modes. J Dent. Mater. 2006;22(6):533-544.
2014;42(7):800-807. [Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
[Full text links] [CrossRef ] [PubMed] Google Scholar Scopus 20. Torii Y, Itou K, Nishitani Y, et al. Effect of phosphoric acid etching
14. Munoz MA, Luque-Martinez I, Malaquias P, et al. In vitro prior to self-etching primer application on adhesion of resin
longevity of bonding propertiesof universal adhesives to dentin. composite to enamel and dentin. Am J Dent. 2002;15(5):305-308.
Oper Dent. 2015;40(3):282-292. [PubMed] Google Scholar Scopus
[Full text links] [CrossRef ] [PubMed] Google Scholar 21. Chen C, Niu LN, Xie H, et al. Bonding of universal adhesives
15. McLean DE, Meyers EJ, Guillory VL, Vandewalle KS. Enamel to dentine--Old wine in new bottles? J Dent. 2015;43(5):525-536.
bond strength of new universal adhesive bonding agents. Oper [Full text links] [CrossRef ] [PubMed] Google Scholar
Dent. 2015;40(4):410-417. 22. Van Meerbeek B, Yoshihara K, Yoshida Y, et al. State of the art of
[Full text links] [CrossRef ] [PubMed] Google Scholar self-etch adhesives. Dent Mater. 2011;27(1):17-28.
16. Takamizawa T, Barkmeier WW, Tsujimoto A, et al. Influence [Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
of different etching modes on bond strength and fatigue 23. Wang Y, Spencer P. Continuing etching of an all-in-one
strength to dentin using universal adhesive systems. Dent Mater. adhesive in wet dentin tubules. J Dent Res. 2005;84(4):350-354.
2016;32(2):e9-e21. [Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
[Full text links] [CrossRef ] [PubMed] Google Scholar Scopus 24. Perdigão J, Kose C, Mena-Serrano AP, et al. A new universal
17. Tay FR, Pashley DH, Yiu C, et al. Nanoleakage types and simplified adhesive: 18-month clinical evaluation. Oper Dent.
potential implications: evidence from unfilled and filled adhesives 2014;39(2):113-127.
with the same resin composition. Am J Dent. 2004;17(3):182-190. [Full text links] [CrossRef ] [PubMed] Google Scholar Scopus
[PubMed] Google Scholar Scopus 25. Harada N, Yamada T, Inokoshi S, Tagami J. Tensile bond
18. Yoshida Y, Nagakane K, Fukuda R, et al. Comparative study strengths and adhesive interfaces of ten dentin bonding systems.
on adhesive performance of functional monomers. J Dent Res. J Med Dent Sci. 1998;45(2):85-96.
2004;83(6):454-458. [PubMed] Google Scholar Scopus

Andre Figueiredo REIS
DDS, MS, PhD, Clinical Associate Professor
Department of Restorative Dental Sciences
Division of Operative Dentistry
College of Dentistry, University of Florida
Gainesville, FL, USA

CV
Dr. Andre Reis earned his dental degree in 1999 from the Campinas State University in Sao Paulo, Brazil. He got his
Master’s degree in Operative Dentistry in 2003 and PhD in 2005. From 2006 to 2018 he was actively involved in teaching
and research at the Guarulhos University. Dr. Reis joined the University of Florida in 2018, as a Clinical Associate Professor
in the division of Operative Dentistry.
Dr. Reis is the 2005 recipient of the Paffenbarger Award (Academy of Dental Materials), and 2006 recipient of the Hatton
Award (IADR). He has presented numerowus lectures and hands-on seminars nationally and internationally. He has
published over 70 articles on the study of Adhesive and Esthetic Dentistry materials and techniques. He is involved in
patient care devoted to Restorative and Esthetic Dentistry.

116 Stoma Edu J. 2019;6(2): 111-117 http://www.stomaeduj.com
EFFECTS OF ETCHING MODE ON BOND STRENGTH OF UNIVERSAL
ADHESIVES

Original Articles
Questions
1. Universal adhesives can be applied in:
qa. Self-etching mode;
qb. Etch-and-rinse mode;
qc. Selective etching mode;
qd. All the answers are correct.

2. What are the advantages of using the self-etching mode when applied on deep
dentin?
qa. Lower post-operative sensitivity, due to maintenance of smear plugs and shallower demineralization in
comparison with 35% phosphoric acid etching;
qb. Higher bond strengths;
qc. Self-etching adhesives don’t need to be light-cured;
qd. Better esthetics.

3. Depending on the pH, self-etch adhesives may be classified into ultra-mild (pH > 2.5, 0.2–0.5
µm interaction depth), mild (pH ≈ 2; 0.5–1 µm interaction depth), intermediate (pH, 1–2; 1–2
µm interaction depth), and strong (pH < 1, > 5 µm interaction depth, similar to etching with
phosphoric acid). About the adhesives/ pH, it is correct to say that:
qa. Lower pH results in more aggressive demineralization;
qb. Lower pH results in higher hydrophilicity;
qc. For ultra-mild and mild self-etching adhesives, enamel selective etching with phosphoric acid is
recommended;
qd. All the answers are correct.

4. The potential to chemically interact with interfacial hydroxyapatite might be
helpful in the adhesion process. This interaction occurs with mild self-etching
adhesives that partially demineralize the dentin surface. It has been shown that
MDP (10-methacryloxydecyl dihydrogen phosphate) is effective in bonding to
hydroxyapatite, and seems to be very stable. It is correct to say that:
qa. All functional monomers are the same;
qb. The specific molecular formula of the functional monomer and the dissolution rate of its calcium salt are
thought to influence bonding performance;
qc. MDP is the only functional monomer available in the market;
qd. All Universal Adhesives present MDP in their composition.

Stomatology Edu Journal 117