Rezende et al. 2016

Prévia do material em texto

Vol 18, No 1, 2016 29
Effects of Dentin Moisture on Cementation of Fiber Posts 
to Root Canals 
Eluise C. Rezendea / Giovana Mongruel Gomesb / Anna Luiza Szeszc / 
Carlos Eduardo da Silveira Buenod / Alessandra Reise / Alessandro D. Loguercioe
Purpose: Achieving optimal moisture inside the root canal is a challenge during bonding of fiberglass posts. This 
study evaluated the effect of different moisture patterns on the push-out bond strength (PBS) and nanoleakage 
(NL) of fiber posts bonded to the root canal of two simplified etch-and-rinse adhesives.
Materials and Methods: The roots of 72 human premolars were endodontically prepared and divided into 6 groups 
according to the combination of the main factors: adhesive (Ambar and Adper Single Bond 2) and moisture (dry, wet, 
and overwet). The posts were cemented and after 1 week, the roots were cross sectioned into 6 disks. Two disks 
each were obtained from the cervical, middle, and apical thirds, and the PBS test was carried out (0.5 mm/min; 
n = 8). The NL was evaluated by scanning electron microscopy after the immersion of specimens in 50% silver 
 nitrate (n = 4). The failure pattern was examined on all debonded specimens. Data were analyzed by three-way re-
peated measures ANOVA and Tukey’s test (5%).
Results: For both adhesives, higher PBS values and lower NL were observed in the wet groups, and lower PBS and 
higher NL in the dry group. In general, the overwet condition showed intermediate results.
Conclusions: The root dentin walls should be left slightly moist before performing fiber post cementation proced-
ures.
Keywords: dentin moisture, bond strength, fiber posts, resin cements, root dentin.
J Adhes Dent 2016; 18: 29–34. Submitted for publication: 19.05.15; accepted for publication: 30.11.15 
doi: 10.3290/j.jad.a35516 
a PhD Student, São Leopoldo Mandic Dental Research Center, Campinas, São 
Paulo, Brazil. Idea, hypothesis, experimental design, performed the experi-
ments, wrote the manuscript, contributed substantially to discussion.
b Adjunct Professor, Department of Restorative Dentistry, School of Dentistry, 
State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil. performed the 
experiments, wrote the manuscript, contributed substantially to discussion.
c PhD student, Department of Restorative Dentistry, School of Dentistry, State 
University of Ponta Grossa, Ponta Grossa, Paraná, Brazil. wrote the manu-
script, contributed substantially to discussion.
d Adjunct Professor, São Leopoldo Mandic Dental Research Center, Campinas, 
São Paulo, Brazil. Idea, hypothesis, consulted on and performed statistical 
evaluation, contributed substantially to discussion.
e Adjunct Professor, Department of Restorative Dentistry, School of Dentistry, 
State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil. Idea, hypothe-
sis, experimental design, consulted on and performed statistical evaluation, 
wrote the manuscript, contributed substantially to discussion.
Correspondence: Professor A. Loguercio, School of Dentistry, Department of 
Restorative Dentistry, State University of Ponta Grossa. Rua Carlos Cavalcanti, 
4748, Bloco M, Sala 64A – Uvaranas, Ponta Grossa, Paraná, Brazil 84030-900. 
Tel:+55-429-902-9903. e-mail: aloguercio@hotmail.com 
because of the esthetic features of the fiberglass posts 
and the low risk of root fractures.5,31.
However, bonding to radicular dentin offers less favor-
able conditions than in the case of coronal dentin, and it is 
still considered the weakest link of the restorative proce-
dure.12 The success of adhesion to the root dentin is di-
rectly associated with the hybridization quality that results 
from adhesive infiltration and the enmeshing of exposed 
collagen fibrils in the hybridized complex.11 
Root collagen fibrils are exposed after acid etching. Fol-
lowing rinsing, the mineral phase of the superficial dentin is 
completely removed, leaving the collagen fibrils literally sus-
pended in water. If the demineralized dentin matrix is air 
dried, the collagen fibrils are brought closer together, result-
ing in a demineralized zone with reduced permeability to 
resin monomers.16,20
A common way to avoid this unfavorable condition is to 
keep the demineralized dentin hydrated prior to adhesive 
application. This is the so-called wet bonding technique. 
Several studies have shown that the optimal moisture con-
dition is dependent on the type of solvent present in the 
adhesive system and the method of adhesive applica-
tion.10,15,22,23,32,33
The use of fiberglass posts cemented with simplified ad-hesive systems and resin cements has become the pre-
ferred choice for restoration of endodontically treated teeth, 
30 The Journal of Adhesive Dentistry
Rezende et al
If the achievement of an optimum degree of moisture is 
difficult even in conditions allowing visual inspection, this 
poses a major obstacle when it comes to root dentin, 
where access to and visualization of the root canal walls 
are extremely limited. Previous studies reported that differ-
ent levels of residual moisture in the root walls affect the 
adhesion and sealing properties of root canal sealers17,34 
and self-adhesive resin cements.1 
To the extent of our knowledge, no study has so far eval-
uated the impact of dentin root moisture on the effective-
ness of fiberglass posts cemented with simplified adhesive 
systems and resin cements. Therefore, the purpose of the 
present study was to compare the push-out bond strength, 
nanoleakage, and fracture patterns of fiber posts cemented 
with simplified etch-and-rinse adhesives to root dentin with 
different moisture levels.
MATERIALS AND METHODS
The Ethics Committee of the local university approved this 
study (protocol # 268.529). Seventy-two extracted human 
maxillary premolars with a root length of 14 mm measured 
from the cementoenamel junction (CEJ) were used. The 
teeth were stored in distilled water at 4°C and were used 
within 6 months after extraction.
Preparation of the Specimens and Experimental 
Groups
The teeth were sectioned transversely immediately below 
the CEJ using a low-speed diamond saw (Isomet 1000, 
Buehler; Lake Bluff, IL, USA). After achieving endodontic 
access, a #10 Flexofile was inserted into each canal until it 
was visible at the apical foramen, and one millimeter was 
subtracted from this length to yield the working length. The 
crown-down technique was used for instrumentation with 
Gates Glidden drills #2 to #4 with apical enlargement to 
size 40 and a .06 taper. After every change of instrument, 
the canal was irrigated alternately with 1 ml of 1% NaOCl 
and 17% EDTA solutions. The roots were dried with paper 
points (Dentsply Maillefer; Petrópolis, RJ, Brazil) and filled 
by vertical compaction of warm gutta-percha and resin-
based sealer (AH Plus, DeTrey, Dentsply; Konstanz, Ger-
many). The root access was temporarily filled with a chemi-
cally polymerized glass-ionomer cement (Maxxion R, FGM; 
Joinville, SC, Brazil) and the specimens were stored at 
37°C in 100% humidity.
After one week, the gutta-percha was removed using 
Gates Glidden burs, leaving 4 mm of the apical seal. The 
post space was prepared with the drill corresponding to the 
#2 fiber post at low speed (Whitepost DC #2, FGM) to a 
fixed depth of 10 mm from the CEJ. After the post space 
preparations, the root canals were irrigated with 10 ml of 
distilled water and dried with paper points. One bur was 
used for only six preparations.
At this point, the teeth were randomly divided into 
6 groups (n = 12), resulting from the combination of the 
main factors “adhesive system/resin-cement” (Ambar/All 
Cem[AM/AC; FGM] and Adper Single Bond 2/RelyX-ARC 
[SB/RX; 3M ESPE, St. Paul, MN, USA]) and “moisture con-
trol” (dry, wet, and overwet). 
Bonding Procedures
For the bonding procedures, the root canalwalls were 
etched with 35% phosphoric acid (Condac, FGM) for 15 s, 
followed by water rinsing for 15 s. For the dry group, the 
root canal was dried for 10 s with an air stream from the 
dental syringe (1 bar pressure) positioned 1.5 to 2 cm from 
the cervical root area, followed by the use of three consecu-
tive paper points. For the wet group, the root canal was 
dried for 5 s with the same dental syringe (1.5 to 2 cm dis-
tance, 1 bar pressure) followed by application of two con-
secutive paper points. For the overwet group, the root canal 
was dried for 2 s with the same dental syringe (1.5 to 2 cm 
distance, 1 bar pressure) and only one paper point. 
Subsequently, adhesives were applied inside the root 
canals with microbrushes (Cavibrush long, FGM). Excess 
adhesive was removed with a paper point. Each resin ce-
ment was inserted with a Centrix syringe (DFL; Rio de 
 Janeiro, RJ, Brazil) and the fiber posts (Whitepost DC #2, 
FGM, 13 mm in length) were seated and immediately light 
activated for 40 s (Radii Cal, SDI; Bayswater, Australia; 
1200 mW/cm2). 
Before starting the study, we employed 15 teeth for vali-
dation of the method used to produce different patterns of 
moisture within the root canal. The roots were instrumented 
and prepared as previously described. Then the mass of 
each tooth (m1) was measured in an analytical balance to 
the nearest 4 decimals (Mettler, type H6; Columbus, OH, 
USA; capacity to 160 g). Thereafter, the tooth was condi-
tioned with the etchant and the root canal was left dry, wet, 
or overwet according to the protocol described earlier. 
Again, the mass of the tooth was measured (m2). All these 
procedures were performed in a room with a temperature 
ranging from 18°C to 22°C and with a relative humidity of 
about 50%. The difference in the mass (m1 – m2) was cal-
culated and these variations were assumed to be due to 
differences in the water content. 
Push-out Bond Strength Test
After storage in water at 37°C for one week, the specimens 
were sectioned perpendicular to the long axis into six 1-mm 
serial slices under water cooling (Isomet 1000, Buehler). 
Both sides of each slice were photographed with an optical 
microscope (Olympus, model BX 51; Tokyo, Japan) at 40X 
magnification to measure the coronal and apical diameters 
of the posts in order to calculate the individual bonding 
areas (UTHSCSA ImageTool 3.0 software; University of 
Texas Health Science Center; San Antonio, TX, USA).
The push-out test (n = 8 teeth for each experimental 
group) was performed in a universal testing machine at 
0.5 mm/min and the maximum failure load calculated in 
MPa.4,6 The failure mode was also evaluated by light mi-
croscopy and classified according to previously published 
studies.6,13
Vol 18, No 1, 2016 31
Rezende et al
Nanoleakage Evaluation
For nanoleakage evaluation (n = 4 teeth per experimental 
group), the slices were immersed in 50 wt% ammoniacal 
silver nitrate solution for 48 h and then photodeveloped to 
allow deposition of silver ions as metallic silver grains 
within voids along the bonded interface.2,29.After polishing 
with up to 2500-grit SiC paper, each slice was cleaned ul-
trasonically, air dried, mounted on stubs, and sputter 
coated with gold (MED 010, Balzers Union; Balzers, Liech-
tenstein). The resin/dentin interfaces were analyzed using 
SEM operated in backscattered mode (SSX-550, 
 Shimadzu; Tokyo, Japan). The relative percentage of 
nanoleakage at the bonded interface was measured in me-
dial, distal, vestibular and lingual regions of the slice in a 
manner similar to that described in an earlier study.21
Statistical Analysis
The validation data were submitted to one-way ANOVA and 
Tukey’s test (α = 0.05). Data of push-out bond strength and 
nanoleakage tests were evaluated by three-way repeated 
measures ANOVA (cementation system vs moisture condi-
tion vs root third) and Tukey’s test (α = 5%).
RESULTS
One-way ANOVA detected statistically significant differences 
among moisture patterns (p = 0.0001), which indicate that 
the amount of water within the root canal was different 
among groups (Table 1).
Three-way ANOVA showed statistically significant differ-
ences for the cross-product interaction cementation system 
vs moisture condition vs root third in both the push-out 
(p = 0.001) and nanoleakage tests (p = 0.0001). 
The highest bond strength values were observed in the 
groups where dentin was kept wet, regardless of the adhe-
sive/cement used and the root third (p < 0.05; Table 2). In 
general, the bond strength at the cervical third was higher than 
that at the apical third for both combinations of adhesive/ce-
ment used and the moisture degree (p < 0.05; Table 2).
Fig 1 Representative scanning electron microscopic images of the post/cement/adhesive root interfaces bonded with Ambar/AllCem in all 
conditions. A higher amount of nanoleakage was observed under the apical third for all moisture conditions, which occurred throughout the en-
tire thickness of the hybrid layer (HL) (pointers in g–i). NL was significantly reduced with wet conditions, mainly in the cervical third (compare b 
with a and c) and middle third (compare e with d and f). Ce, resin cement; RC, root canal. 
 
AP
IC
AL
 
M
ED
IU
M
 
C
ER
VI
C
AL
 DRY WET OVERWET
a
Ce
) ) )HL
RC
b
Ce )
HL
RC
c
Ce )
HL
RC
))
f
Ce
)
HL
RC
)
e
Ce )
HL
RC
)
d
Ce
)HL
RC
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g
Ce
HL
RC
) ) ) )
h
Ce
HL
RC
) ) ) )
i
Ce
HL
RC
) ) ) )
32 The Journal of Adhesive Dentistry
Rezende et al
Since these two adhesives rely on the same bonding 
strategy, the etch-and-rinse approach, they require the den-
tin substrate to be kept moist after acid conditioning.18 As 
long as dentin is kept fully hydrated, the dentin matrix does 
not collapse and free space is available for resin infiltra-
tion,20 which may explain the higher values of the wet 
groups in the present study. However, the wet bonding tech-
nique is not easily accomplished by clinicians, as it pres-
ents a challenge in clinical situations. 
The lowest bond strength values were observed for the 
dry groups. It is known that when demineralized dentin is 
air dried, the water within the collagen matrix is removed 
and the collagen fibrils are brought into close contact. They 
form weak interpeptide bonds that cause the matrix to 
shrink, and become stiff16,19 and practically impermeable 
to resin adhesives.26 Even worse, excessive dessication 
may remove the water present in the dentinal tubules,33 
which may in turn hamper effective penetration of the adhe-
sive systems and thus compromise the quality of adhesion, 
as was shown in the present study.
The “overwet” condition showed an intermediate perfor-
mance with no significant difference when compared to the 
other two moisture conditions (dry and wet). Overall, these 
results suggested that among different levels of intracanal 
moisture, the dry and overwet conditions should only repre-
sent extreme experimental scenarios which should be 
avoided in the clinical situation. 
Although the methods of excess water removal from the 
groups “wet” and “overwet” were not very different, a dra-
matic difference between wet and overwet groups in terms 
of bond strength and nanoleakage was observed when they 
were compared to one another. Different research centers 
showed that excess water limits infiltration of the resinous 
monomers into the demineralized root dentin.14,27,28 Addi-
tionally, under overwet conditions, water blisters are formed 
in the adhesive interfaces due to phase separation of hy-
drophilic and hydrophobic monomers.26,27,29.
Statistically significantly less nanoleakage was observed 
in the groups where dentin was kept wet, mainly in the cer-vical and middle thirds, regardless of the adhesive/cement 
used (p < 0.05; Fig 1 and Table 2). For Ambar/AllCem at 
the cervical third, nanoleakage was even lower than that 
observed in the Adper Single Bond 2/Rely-X ARC group 
(p < 0.05; Table 2).
Independent of root moisture condition, both adhesive/
cement groups showed statistically significantly higher 
nanoleakage (Figs 1g to 1i) and lower bond strength in the 
apical third (p < 0.05; Table 2). Only adhesive failures be-
tween dentin and cement and mixed failures were ob-
served. The most predominant failure pattern in all groups 
was adhesive (between dentin and resin cement) (Table 2).
DISCUSSION
In the present study, the degree of residual moisture af-
fected the fiber post adhesion to radicular dentin for the 
two simplified etch-and-rinse adhesives tested. The highest 
bond strength values were observed under the wet condi-
tion for both adhesive/cements.
Table 2 Means and standard deviations of push-out bond strength (MPa) and nanoleakage (%), as well as failure 
mode for the experimental groups 
Adhesive 
systems
Root 
third
Push-out bond strength Nanoleakage Failure mode*
Dry Wet Overwet Dry Wet Overwet Dry Wet Over-
wet
Ambar/
AllCem
Cervical 7.5 ± 1.3B,C 15.0 ± 3.5A 12.2 ± 3.6A 20.3 ± 4.1b,c 10.3 ± 2.0a 16.1 ± 4.1b 7/1 8/0 4/4
Medium 4.8 ± 1.5C,D 10.0 ± 2.7A,B 7.8 ± 2.7B 27.5 ± 6.3c 15.3 ± 3.9a,b 18.3 ± 4.3b,c 6/2 6/2 4/4
Apical 3.6 ± 2.7D 7.9 ± 3.0B 4.6 ± 3.8C,D 45.2 ± 6.7e 43.2 ± 6.1e 53.3 ± 4.9f 5/3 5/3 3/5
Adper 
Single 
Bond 2 /
RelyX-ARC
Cervical 7.4 ± 1.7B,C 14.1 ± 3.1A 10.5 ± 2.0A,B 16.7 ± 2.7b 18.2 ± 3.2b 25.5 ± 4.2c 6/2 7/1 5/3
Medium 4.7 ± 2.2C,D 10.4 ± 4.3A,B 6.6 ± 1.8C 29.1 ± 4.1c,d 23.8 ± 6.2b,c 29.3 ± 3.2c,d 7/1 6/2 3/5
Apical 3.1 ± 2.1D 6.3 ± 3.3C 3.9 ± 2.9D 50.3 ± 3.8f 46.5 ± 6.7e 53.9 ± 5.9f 6/2 5/3 4/4
Different superscript capital letters (push-out bond strength) and lowercase letters (nanoleakage) indicate that means are statistically different (p < 0.05). *The 
first value is adhesive dentin-cement failure and the second is mixed failure.
Table 1 Means and standard deviations of the varia-
tion in mass (%) before and after etching and moisture 
standardization
Experimental groups Mass variation (x 102)
Dry -0.07 ( 0.03 A
Wet 0.42 ( 0.2 B
Overwet 1.62 ( 0.2 C
Different superscript letters indicate that means are statistically different 
(p < 0.05).
Vol 18, No 1, 2016 33
Rezende et al
The similarity of the bond strength values of the adhesive 
systems under the different moisture conditions is probably 
due to the fact that they share the same type of solvent, ie, 
ethanol. It has been demonstrated that the optimal moisture 
degree depends on the type of the solvent present in each 
adhesive system.22 However, a slight difference between the 
two adhesives was observed in the nanoleakage evaluation. 
Nanoleakage reveals the location of defects at the resin/
dentin interface that could work as pathways for degradation 
of resin-dentin bonds over time. Silver nitrate occupies nano-
meter-sized spaces around denuded collagen fibrils, where 
resin failed to infiltrate, or where residual water was not dis-
placed by the adhesive resin.25 The lower nanoleakage of 
Ambar/AllCem suggests that the adhesive Ambar probably 
displaces water more effectively, which may be due to the 
presence of higher concentration of solvents than in Adper 
Single Bond 2. This may allow more water evaporation and a 
deeper infiltration of adhesive monomers.
Although good results were obtained with wet dentin in 
comparison with dry and overwet dentin conditions, wet 
bonding is a technique-sensitive procedure. Optimum bond-
ing with etch-and-rinse adhesives depends on several fac-
tors. Among them, the maintenance of adequately moist 
demineralized dentin is difficult to achieve in clinical prac-
tice, especially in the root canal. The ethanol-wet bonding 
technique has been claimed to minimize the technique sen-
sitivity of water-wet bonding, as it replaces the water in 
acid-etched dentin matrices with ethanol.24 Previous stud-
ies showed higher immediate bond strength values and re-
duced nanoleakage in root canals when the ethanol-wet 
bonding technique was applied.3,8,9 Additionally, compared 
to the results of the current study, bonding to the apical 
root canal seems to be better when ethanol bonding is per-
formed, indicating that in general, the ethanol-wet bonding 
technique minimizes the technique-sensitivity of bonding 
within the root canal.
Another advantage is that the ethanol-wet bonding tech-
nique allows the infiltration of more hydrophobic resin mono-
mers, which are less susceptible to degradation.30 However, 
this technique can also be used associated with more simpli-
fied and hydrophilic etch-and-rinse adhesives.3,7 Additionally, 
most of the studies reported that ethanol-saturated dentin 
produced stable dentin-bonded interfaces after 6 and 
12 months of water storage.3,4,9 Future studies should be 
conducted to compare the technique sensitivity of the etha-
nol-bonding technique with that of water-wet bonding.
CONCLUSION
The results of this study indicate that the experimental lev-
els of dentin moisture, from dry to overwet, affect the per-
formance of adhesive systems. Clinicians should leave root 
canals slightly moist before cementation of fiber posts. This 
was achieved with 10 s of air drying associated with 
2 paper points. Further studies are required to validate 
whether keeping the dentin slightly moist favors the long-
term bonding of fiber posts to root canals.
ACKNOWLEDGMENTS
Eluise Rezende performed this study as partial fulfillment of her PhD 
degree at the São Leopoldo Mandic University, Brazil. This study 
was partially supported by the National Council for Scientific and 
Technological Development (CNPq) under grants 304105/2013-9 
and 301891/2010-9. The authors are very grateful to FGM Dental 
Products and 3M ESPE (Brazil) for the generous donation of the ad-
hesives and resin cements used here. 
REFERENCES
1. Aktemur Turker S, Uzunoglu E, Yilmaz Z. Effects of dentin moisture on 
the push-out bond strength of a fiber post luted with different self-adhe-
sive resin cements. Restor Dent Endod 2013;38:234-240.
2. Babb BR, Loushine RJ, Bryan TE, Ames JM, Causey MS, Kim J, Kim YK, 
Weller RN, Pashley DH, Tay FR. Bonding of self-adhesive (self-etching) 
root canal sealers to radicular dentin. J Endod 2009;35:578-582.
3. Bitter K, Aschendorff L, Neumann K, Blunck U, Sterzenbach G. Do 
chlorhexidine and ethanol improve bond strength and durability of adhesion 
of fiber posts inside the root canal? Clin Oral Investig 2014;18:927-934.
4. Cecchin D, de Almeida JF, Gomes BP, Zaia AA, Ferraz CC. Influence of 
chlorhexidine and ethanol on the bond strength and durability of the ad-
hesion of the fiber posts to root dentin using a total etching adhesive 
system. J Endod 2011;37:1310-1315.
5. Coelho CS, Biffi JC, Silva GR, Abrahao A, Campos RE, Soares CJ. Finite 
element analysis of weakened roots restored with composite resin and 
posts. Dent Mater J 2009;28:671-678.
6. Costa Dantas MC, do Prado M, Costa VS, Gaiotte MG, Simao RA, Bas-
tian FL. Comparison between the effect of plasma and chemical treat-
ments on fiber post surface. J Endod 2012;38:215-218.
7. de Barros L, Apolonio FM, Loguercio AD, de Saboia V. Resin-dentin bonds 
of etch-and-rinse adhesives to alcohol-saturated acid-etched dentin. 
J Adhes Dent 2013;15:333-340.
8. Duan SS, Ouyang XB, Pei DD, Huo YH, Pan QH, Huang C. Effects of etha-
nol-wet bonding technique on root dentine adhesion. Chin J Dent Res 
2011;14:105-111.
9. Ekambaram M, Yiu CK, Matinlinna JP, Chang JW, Tay FR, King NM. Effect 
of chlorhexidine and ethanol-wet bonding with a hydrophobic adhesive to 
intraradicular dentine. J Dent 2014;42:872-882.
10.Faria ESAL, Fabiao MM, Sfalcin RA, de Souza Meneses M, Santos-
Filho PC, Soares PV, Martins LR. Bond strength of one-step adhesives 
under different substrate moisture conditions. Eur J Dent 2009;3: 
290-296.
11. Ferrari M, Vichi A, Grandini S. Efficacy of different adhesive techniques 
on bonding to root canal walls: an SEM investigation. Dent Mater 
2001;17:422-429.
12. Ferrari M, Vichi A, Mannocci F, Mason PN. Retrospective study of the clin-
ical performance of fiber posts. Am J Dent 2000;13:9B-13B.
13. Gomes GM, Gomes OM, Reis A, Gomes JC, Loguercio AD, Calixto AL. 
 Effect of operator experience on the outcome of fiber post cementation 
with different resin cements. Oper Dent 2013;38:555-564.
14. Jacobsen T, Söderholm KJ. Some effects of water on dentin bonding. 
Dent Mater 1995;11:132-136.
15. Lee Y, Park JW. Effect of moisture and drying time on the bond strength 
of the one-step self-etching adhesive system. Restor Dent Endod 2012; 
37:155-159.
16. Maciel KT, Carvalho RM, Ringle RD, Preston CD, Russell CM, Pashley 
DH. The effects of acetone, ethanol, HEMA, and air on the stiffness of 
human decalcified dentin matrix. J Dent Res 1996;75:1851-1858.
17. Nagas E, Uyanik MO, Eymirli A, Cehreli ZC, Vallittu PK, Lassila LV, 
Durmaz V. Dentin moisture conditions affect the adhesion of root canal 
sealers. J Endod 2012;38:240-244.
18. Nakajima M, Kanemura N, Pereira PN, Tagami J, Pashley DH. Compara-
tive microtensile bond strength and SEM analysis of bonding to wet and 
dry dentin. Am J Dent 2000;13:324-328.
19. Pashley DH, Carvalho RM, Tay FR, Agee KA, Lee KW. Solvation of dried den-
tin matrix by water and other polar solvents. Am J Dent 2002;15:97-102.
20. Pashley DH, Ciucchi B, Sano H, Horner JA. Permeability of dentin to adhe-
sive agents. Quintessence Int 1993;24:618-631.
21. Reis A, Grande RH, Oliveira GM, Lopes GC, Loguercio AD. A 2-year evalu-
ation of moisture on microtensile bond strength and nanoleakage. Dent 
Mater 2007;23:862-870.
34 The Journal of Adhesive Dentistry
Rezende et al
22. Reis A, Loguercio AD, Azevedo CL, de Carvalho RM, da Julio Singer M, 
Grande RH. Moisture spectrum of demineralized dentin for adhesive sys-
tems with different solvent bases. J Adhes Dent 2003;5:183-192.
23. Reis A, Pellizzaro A, Dal-Bianco K, Gones OM, Patzlaff R, Loguercio AD. 
Impact of adhesive application to wet and dry dentin on long-term resin-
dentin bond strengths. Oper Dent 2007;32:380-387.
24. Sadek FT, Pashley DH, Nishitani Y, Carrilho MR, Donnelly A, Ferrari M, Tay 
FR. Application of hydrophobic resin adhesives to acid-etched dentin with an 
alternative wet bonding technique. J Biomed Mater Res A 2008;84:19-29.
25. Sano H. Microtensile testing, nanoleakage, and biodegradation of resin-
dentin bonds. J Dent Res 2006;85:11-14.
26. Spencer P, Swafford JR. Unprotected protein at the dentin-adhesive inter-
face. Quintessence Int 1999;30:501-507.
27. Spencer P, Wang Y. Adhesive phase separation at the dentin interface 
under wet bonding conditions. J Biomed Mater Res 2002;62:447-456.
28. Tay FR, Gwinnett JA, Wei SH. Micromorphological spectrum from overdry-
ing to overwetting acid-conditioned dentin in water-free acetone-based, 
single-bottle primer/adhesives. Dent Mater 1996;12:236-244.
29. Tay FR, Pashley DH, Yoshiyama M. Two modes of nanoleakage expres-
sion in single-step adhesives. J Dent Res 2002;81:472-476.
30. Tjaderhäne L, Nascimento FD, Breschi L, Mazzoni A, Tersariol IL, Ger-
aldeli S, Tezvergil-Mutluay A, Carrilho M, Carvalho RM, Tay FR, Pashley 
DH. Strategies to prevent hydrolytic degradation of the hybrid layer-A re-
view. Dent Mater 2013;29:999-1011.
31. Torabi K, Fattahi F. Fracture resistance of endodontically treated teeth re-
stored by different FRC posts: an in vitro study. Indian J Dent Res 
2009;20:282-287.
32. Umino A, Nikaido T, Sultana S, Ogata M, Tagami J. Effects of smear layer 
and surface moisture on dentin bond strength of a waterless all-in-one 
adhesive. Dent Mater J 2006;25:332-338.
33. Zhang ZX, Huang C, Zheng TL, Wang S, Cheng XR. Effects of residual 
water on microtensile bond strength of one-bottle dentin adhesive sys-
tems with different solvent bases. Chin Med J (Engl) 2005;118: 
1623-1628.
34. Zmener O, Pameijer CH, Serrano SA, Vidueira M, Macchi RL. Significance 
of moist root canal dentin with the use of methacrylate-based endodontic 
sealers: an in vitro coronal dye leakage study. J Endod 2008;34:76-79.
Clinical relevance: As for coronal dentin, radicular den-
tin should be left slightly moist before adhesive appli-
cation in root canals to improve the retention of fiber 
posts.