C.E. Article #4-101 (1 credit/AGD code 253)
Research Article
Post-operative sensitivity in glass-ionomer versus adhesive
resin-lined posterior composites
ENOSAKHARE S. AKPATA,BCHD,MDSC,FDS & WALIDSADIQ,BDS,MS
ABSTRACT:
Purpose: To compare objective and subjective assessments of post-operative sensitivity when class 1
cavities, lined with glass-ionomer or adhesive bonding system, were restored with resin-based composite (RBC).
Materials and Methods: Occlusal cavities on homologous contra-lateral posterior teeth in 44 male patients attending
primary health centers in Riyadh, Saudi Arabia were restored with RBC after a cavity lining of either a light cured
glass-ionomer cement (Vitrebond) or an adhesive bonding system (One-Step). Results: Cold response measurements 24 hrs,
7 days and 1 month post-operatively showed that the threshold of pulpal response was significantly lower (P< 0.05) in the
restored teeth when the adhesive bonding system served as cavity liner. In addition, based on the patients' subjective
assessments, the prevalence of mild or severe post-operative sensitivity was significantly higher (P< 0.05), 24 hrs and 7
days post-operatively, in the teeth with the adhesive bonding system as a cavity liner. After a post-operative period of 1
month, however, there was no significant difference (P> 0.05) between the prevalence of post-operative sensitivity when
the restored teeth received a lining of either glass-ionomer or adhesive bonding system. (Am J Dent 2001;14: 34-38).
CLINICAL SIGNIFICANCE: Post-operative sensitivity was more severe and prevalent in posterior teeth following the placement
of occlusal resin-based composite restorations when the cavities were lined with an adhesive resin than when they received a
glass-ionomer lining.
CORRESPONDENCE: Prof. E.S. Akpata, Department of Restorative Dental Sciences, College of Dentistry, King Saud
University, P.O.Box 60169, Riyadh, Saudi Arabia. Fax: 966 1 467 8548. E-mail: akpata@ksu.edu.sa
Introduction
Post-operative sensitivity following resin-based composite
(RBC) restorations may result from microleakage, a condition
that may be minimized by bonding the restoration to the cavity
walls. RBC restorations can be bonded to both enamel and
dentin using modern adhesive bonding systems. As these
bonding systems are capable of sealing off the dentin tubules by
forming resin tags firmly hybridized1 to the etched peritubular dentin, it was hypothesized that post-operative sensitivity would be minimal when adhesive bonding systems are
used for lining cavities for RBC restorations. Similarly, glassionomer cement is known to bond to calcified dental tissues as
well as to RBCs3. When used as a cavity liner in teeth restored
with RBC, glass-ionomer cement has the potential to minimize
microleakage and therefore post-operative sensitivity.
Chan & Swift4 studied microleakage following RBC restorations of cavities lined with three adhesive bonding systems:
All Bond 2,a Gluma 2000,b and Scotchbond Multipurpose.0
They observed that microleakage was less in the group of
teeth that received the adhesive linings, when compared with
the unlined control group. Nevertheless, Yap et af reported
that microleakage was significantly less when cavities restored with RBC were lined with glass-ionomer cement than
when they received an adhesive lining of Scotchbond Multipurpose. Using silver nitrate, Sano et af studied nanoleakage in
the hybrid layer in cavities lined with dentin bonding systems
(Clearfil Liner Bond Systemd and All Bond-2). Both systems
demonstrated silver nitrate accumulation beneath the hybrid
layer, suggesting that irritants might penetrate the hybrid layer
even when cavities were lined with dentin bonding agents.
Browning et af compared post-operative sensitivity from
amalgam restorations in cavities that received an adhesive liner,
OptiBond6 or conventional liner and base. The teeth
that received an adhesive liner were not less sensitive to cold
stimuli than those that received conventional liner and base.
However, reports are scarce on controlled clinical studies
comparing post-operative sensitivity when cavities for posterior
RBC restorations are lined with an adhesive bonding
system or a conventional liner. This study, therefore, compared post-operative sensitivity following Class I posterior
RBC restorations in teeth that received a cavity lining of either
glass-ionomer cement or adhesive bonding system.
Materials and Methods
Selection of patients and informed consent - Approval for this
study was obtained from the College of Dentistry Research
Center of the King Saud University, Riyadh. The nature of the
research was explained to the patients selected from primary
health centers in Riyadh, Saudi Arabia. After the explanation,
the patients gave their consent and agreed to attend follow-up
appointments for at least 1 month.
Forty-four male patients aged 16-52 yrs with homologous
contra-lateral posterior teeth having occlusal caries were selected for the study. The patients were free of orofacial pain,
including toothache.
Selection and isolation of teeth - The homologous contra-lateral posterior teeth selected for the study were neither tender to
percussion nor did they show any sign of periapical radiolucency. If maxillary premolars or molars were selected, both
right and left teeth were restored at the same visit. On the
other hand, if mandibular teeth were selected for the study,
one tooth was restored at each visit, to avoid giving two inferior
dental blocks simultaneously. The teeth selected had small
or moderately large carious lesions. The bucco-lingual
dimension of each carious cavity was less than half the intercuspal width.
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American Journal of Dentistry, Vol. 14, No. 1, February, 2001
The experimental teeth were isolated with rubber dam
throughout the operative procedures. A detailed description of
the operative procedures was given to four general dental
practitioners who carried out the clinical work.
Cavity preparation - After administering local anesthetic, an
occlusal cavity was prepared with a high-speed handpiece using
a number 330 pear-shaped tungsten carbide bur, cooled with a
water spray. Residual caries was removed with the largest
possible spoon excavator. If there was pulp exposure or pink
dentin was visible, the tooth was excluded from the sample. The
enamel walls were smoothened with a water-cooled cylindrical
finishing bur at slow speed. The cavosur-face angle of the
prepared cavity was approximately 90°. The cavity was cleaned
with a water spray from the triple syringe of the dental unit.
The depth of the prepared cavity was measured against the
mesial and distal marginal ridges, using a graduated periodontal probe. In addition, the width of the cavity was recorded
as a proportion of the intercuspal width. For each patient, the
prepared cavity on one of the selected teeth was lined with
glass-ionomer and the contra-lateral homologous tooth with an
adhesive bonding system.
Placement of glass-ionomer lining and etching of enamel
cavity wall - One scoop of light-cured glass-ionomer liner
(Vitrebond0) powder was mixed with one drop of the liquid on a
mixing pad. Using the applicator supplied by the manufacturers, a creamy mix of the liner was spread on the pulpal
floor and dentin axial walls of the cavity. The lining was then
light-cured for 20 s. The enamel walls of the cavity were
etched with 37% phosphoric acid for 20 s, washed with water
for 20 s and then dried for 20 s. The etching was repeated for
20 s if the enamel was not frosty white.
Cavity lining with bonding system - The enamel and dentin
walls on the contra-lateral homologous tooth were etched with
32% phosphoric acid (Uni-etcha) for 15 s, washed, dried, and then
lined with three coats of One-Step3 according to the
manufacturer's instructions. There was randomization in the
selection of the right and left teeth for the adhesive or glassionomer lining.
Restoration with RBC - The lined cavity was restored with three
pie-shaped wedges of heavily filled hybrid RBC (BisFil P a). The
first layer was placed on the buccal wall and then extended
diagonally to the pulpal floor. The RBC was cured from the
buccal direction for 60 s. The procedure was repeated on the
lingual wall, again curing through the lingual enamel for 60 s.
Lastly, the RBC was placed in the mid-portion of the cavity and
cured from the occlusal direction.8 Occlusion was adjusted with a
football-shaped diamond point. The restoration was finally
polished with aluminum oxide polishing paste.
Evaluation of post-operative sensitivity
Objective assessment of post-operative sensitivity - Prior to
cavity preparation, an ice stick of standard diameter and
length, prepared by freezing water in a local anesthetic cartridge, was placed against the buccal surface of the experimental tooth to determine how long it took for the patient to
feel cold sensation. The time was measured, in seconds, with a
stopwatch, and this was recorded as the baseline cold re-
Post-operative sensitivity 35
Table 1. Frequency (%) of experimental teeth.
Left
Right
Molars Premolars
Premolars Total
12(13.6)
Maxillary
Mandibular 16(18.2)
Total
11(12.5)
5 (5.7)
Molars
28(31.8) 16(18.2)
28(31.8)
46
42
11(12.5)
5 (5.7)
12(13.6)
16(18.2)
16(18.2)
88
Table 2. Intercuspal widths of the Class I experimental cavities.
One-Step
Vitrebond
Total
Premolars
Molars
10
8
5
12
1
5
0
3
9
9
7
9
0
9
0
1
32
56
Total
18
17 6
3
18
16 9
1
88
sponse measurement (CRM). At the recall appointment 24
hrs, 7 days and 30 days after the restoration, the CRM was
repeated. The measurement of CRM at the recall visits was by
another dentist who was unaware of the lining that the experimental teeth had received.
Subjective assessment - of post-operative sensitivity - At the
recall visits 24 hrs, 7 days and 30 days post-operatively, each
of the patient's subjective assessment of post-operative sensitivity was recorded. At each of these appointments, the patient
classified the pain from each of the restored teeth into none,
moderate or severe; accordingly, the patient's assessment was
scored on a scale of 1-3, respectively.
Statistical analysis - Chi-square test was used to determine
the statistical significance of the difference between the
widths and depths of the cavities prepared on the homologous
contra-lateral teeth. In addition, paired Mest and Wilcoxon
matched pairs rank sum test were used to compare the objective
and subjective assessments of post-operative sensitivity from
teeth that received a lining of One Step or Vitrebond,
respectively.
Results
Patients and experimental teeth - The mean age of the 44 patients who participated in the study was 27.9 yrs (range 16-52
yrs) and about 70% of them were aged between 16-30 yrs. Of
the 88 experimental teeth, 46 were in the maxilla, while molars
accounted for about 64% of the selected teeth (Table 1).
Cavity width and depth - Most of the prepared cavities were
either about a quarter or a third the intercuspal width of the
posterior teeth: 40% of the cavities lined with One-Step or
Vitrebond were about a quarter the inter-cuspal width, while
36-38% were about a third the inter-cuspal width. Only about 27% of the cavities was more than half the intercuspal width
(Table 2). A Chi-square test showed that there was no statistically significant difference between the widths of the cavities that
received a lining of glass-ionomer or adhesive bonding system.
About 30% of the prepared cavities were 0.5 mm into dentin
while approximately 40% extended 1 mm beyond the den-tinenamel junction (Table 3). Again, a Chi-square test showed
that there was no statistically significant difference between
the depth of the cavities lined with the glass-ionomer or
adhesive bonding system (P> 0.05).
36 Akpata & Sadiq
American Journal of Dentistry, Vol. 14, No. 1, February, 2001
American Journal of Dentistry, Vol. 14, No. I, February, 2001
post-operative period, however, there was no significant difference in the prevalence of post-operative sensitivity in the
teeth lined with the adhesive bonding system or glass-ionomer
(P> 0.05).
Discussion
Class I occlusal cavities were selected for this study because their preparation is relatively easy and involves less
variability than compound cavities. Thus there was no statistically significant difference between the depth and width of the
cavities lined with the glass-ionomer or the adhesive bonding
system. Furthermore, exclusion of cases showing pink dentin at
the pulpal floor of the prepared cavities minimized the confounding effect of pre- and post-operative pulp disease on the
prevalence and severity of post-operative sensitivity. As there
was equal distribution of cases with centric occlusal contact at
the restoration margin among the teeth that received a lining
of the adhesive bonding system or glass-ionomer, it is
unlikely that occlusal breakdown of restoration margins had a
significant effect on the results obtained in this study.
Polymerization shrinkage stresses contribute to postoperative
sensitivity following RBC restoration by causing coronal
deformation and micro-fracture.9 These stresses may be
reduced by incremental filling technique10 and by curing the
RBC indirectly through the cusps; thus, polymerization
shrinkage, directed towards the source of curing light,11 is
towards the axial cavity walls. Although some investigators
question the value of these techniques,12'13 in the present study
precautionary measures of placing the Class I RBC restorations incrementally and curing from the buccal and lingual directions were taken.8
The fact that there was no significant difference between
the mean baseline CRM obtained for the contra-lateral homologous teeth indicates that the measurements with the standardized ice stick was reasonably accurate. The relatively
large standard deviations may be due to biological variation
and sub-clinical histopathological pulpal changes in the carious
experimental teeth.
The significantly higher severity and prevalence of postoperative sensitivity in teeth lined with the adhesive bonding
system was rather surprising, in view of the relatively high
resinous content of One-Step. A number of factors may have
contributed to this finding. The use of the glass-ionomer liner
does not involve acid etching the cavity dentin walls. Consequently, the cement is bonded to both the smear layer and the
underlying dentin wall to block the dentin tubules, and perhaps controlling post-operative sensitivity. In contrast, the
cavity dentin walls were etched with 32% phosphoric acid for
15 s before the application of the adhesive bonding system.
This is capable of removing the smear plugs and opening
(funneling) the ends of the dentinal tubules.14 The open dentin
tubules could then cause post-operative sensitivity by permitting
hydraulic fluid shift due to thermal stimulation or flexion of the
RBC restoration under masticatory load. Additionally, the acid,
on account of its osmotic pressure, might cause dentin fluid
movement, resulting in post-operative sensitivity.15 However,
Cox et a/16 reported the biocompatibility of nine adhesive
systems with exposed and non-exposed dental pulps in
monkeys, while Hebling et a/17 demonstrated more severe
pulpal inflammatory response to adhesive cavity lining of All-
Post-operative sensitivity 37
Bond 2 than to calcium hydroxide in deep cavities in human
teeth. The effect of species difference on these contrasting
reports is, however, uncertain.
The bond mediated by One-Step is mainly micro-mechanical18 rather than chemical. This makes microleakage, and
therefore hydrodynamic fluid shift in the dentin tubules, more
likely in cavities with the adhesive lining than those lined
with glass-ionomer bonded chemically to the cavity walls.
Besides, it has been demonstrated that a demineralized porous
zone, not penetrated by adhesive resin, may exist beneath the
hybrid layer.6 This zone may prevent total sealing of the dentin
tubules, resulting in post-operative sensitivity from cavities
with adhesive lining. It would therefore appear desirable to
develop bonding systems with micro-mechanical and enhanced chemical adhesion, to provide better sealing of dentin
tubules.
It is possible that the application of three coats of OneStep recommended by the manufacturer is insufficient to provide
an uninterrupted layer of the dentin-bonding agent. Future
research should therefore investigate the relationship
between post-operative sensitivity and the number of coats
(up to 6) of the bonding system.
When there is polymerization shrinkage of RBC in a cavity
lined with an adhesive system, the gap formation is usually
between the RBC and the hybrid layer.19 If there is discontinuity in the coating of the cavity wall by the bonding system or
micro-porous zone beneath the hybrid layer, however, hydrodynamic fluid shift or bacterial toxins penetrating the dentin
tubules could cause post-operative sensitivity. In contrast, on
account of its relatively high film thickness and low cohesive
bond strength,20 a glass-ionomer lining is likely to suffer
cohesive bond failure when there is polymerization shrinkage of
the RBC restoration. Under this situation, the glass-ionomer
cement still bonded chemically to the cavity dentin wall,
would block the dentinal tubules, therefore controlling postoperative sensitivity. Another possible explanation for the
difference in post-operative sensitivity due to the two cavity
linings could be that the glass-ionomer, on account of its more
plastic behavior, provided more stress relief to the RBC
restoration and therefore less cavity deformation.
Lining the entire pulpal and axial cavity walls with Vitrebond in half of the experimental teeth in this study facilitated
comparison of post-operative sensitivity between the teeth in
which the cavities were lined with either glass-ionomer or
One-Step. This experimental model may be utilized in the
evaluation of post-operative sensitivity following the use of
other adhesive bonding systems. Nevertheless, as glass-ionomer
liner or base is more often applied selectively to deep areas
of prepared cavities in clinical practice, future studies should
compare post-operative sensitivity from teeth with selective
glass-ionomer lining and those with adhesive lining following
the total etch technique.
a.
b.
c.
d.
e.
Bisco, Schaumburg, IL, USA.
Heraeus Kulzer, Dormagen, Germany.
3M Dental Products, St. Paul, MN, USA.
J. Morita, Osaka, Japan.
Kerr Corp., Orange, CA, USA.
Acknowledgements: We are grateful to Drs. A. Al-Rabiah, F. Al-Rossais, A.
Al-Shayea and H. Al-Robiaan for their clinical input to this investigation.
American Journal of Dentistry, Vol. 14, No. 1, February, 2001
38 Akpata & Sadiq
This project was registered at the King Saud University College of Dentistry
Research Center, NF 1352.
Dr. Akpata is Professor, Department of Restorative Dental Sciences; Dr.
Sadiq is Assistant Professor, Department of Prosthetic Dental Sciences,
College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
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Authors:
Please note: As of March 15, 2001, the address for the Editorial Office of the American
Journal of Dentistry for submission of manuscripts has changed.
Please send all manuscript submissions to:
Dr. Franklin Garcia-Godoy
Biomaterials Research School
of Dental Medicine Tufts
University One Kneeland
Street Boston, MA 02111