Randomized 3-year Clinical Evaluation of Class I and II Posterior Resin Restorations Placed with a Bulk-fill Resin Composite and a One-step Self-etching Adhesive

Abstract

Purpose:
To evaluate the 3-year clinical durability of the flowable bulk-fill resin composite SDR in Class I and Class II restorations.

Materials and methods:
Thirty-eight pairs of Class I and 62 pairs of Class II restorations were placed in 44 male and 42 female patients (mean age 52.4 years). Each patient received at least two extended Class I or Class II restorations that were as similar as possible. In all cavities, a one-step self-etching adhesive (XenoV+) was applied. One of the cavities of each pair was randomly assigned to receive the flowable bulk-fill resin composite SDR in increments up to 4 mm as needed to fill the cavity 2 mm short of the occlusal cavosurface. The occlusal part was completed with an ormocer-based nanohybrid resin composite (Ceram X mono+). In the other cavity, only the resin composite CeramX mono+ was placed in 2 mm increments. The restorations were evaluated using slightly modified USPHS criteria at baseline and then annually for 3 years. Caries risk and bruxing habits of the participants were estimated.

Results:
No post-operative sensitivity was reported. At the 3-year follow-up, 196 restorations - 74 Class I and 122 Class II - were evaluated. Seven restorations failed (3.6%), 4 SDR-CeramX mono+ and 3 CeramX mono+ only restorations, all of which were Class II. The main reason for failure was tooth fracture, followed by resin composite fracture. The annual failure rate (AFR) for all restorations (Class I and II) was 1.2% for the bulkfilled restorations and 1.0% for the resin composite-only restorations (p > 0.05). For the Class II restorations, the AFR was 2.2% and 1.6%, respectively.

Conclusion:
The 4-mm bulk-fill technique showed good clinical effectiveness during the 3-year follow-up.

Full text

Vol 17, No 1, 2015 81
Randomized 3-year Clinical Evaluation of Class I and
II Posterior Resin Restorations Placed with a Bulk-fill
Resin Composite and a One-step Self-etching Adhesive
Jan WV van Dijkena / Ulla Pallesenb
Purpose: To evaluate the 3-year clinical durability of the flowable bulk-fill resin composite SDR in Class I and
Class II restorations.
Materials and Methods: Thirty-eight pairs of Class I and 62 pairs of Class II restorations were placed in 44 male
and 42 female patients (mean age 52.4 years). Each patient received at least two extended Class I or Class II
restorations that were as similar as possible. In all cavities, a one-step self-etching adhesive (XenoV+) was ap-
plied. One of the cavities of each pair was randomly assigned to receive the flowable bulk-fill resin composite
SDR in increments up to 4 mm as needed to fill the cavity 2 mm short of the occlusal cavosurface. The occlusal
part was completed with an ormocer-based nanohybrid resin composite (Ceram X mono+). In the other cavity,
only the resin composite CeramX mono+ was placed in 2 mm increments. The restorations were evaluated using
slightly modified USPHS criteria at baseline and then annually for 3 years. Caries risk and bruxing habits of the
participants were estimated.
Results: No post-operative sensitivity was reported. At the 3-year follow-up, 196 restorations – 74 Class I
and 122 Class II – were evaluated. Seven restorations failed (3.6%), 4 SDR-CeramX mono+ and 3 CeramX
mono+ only restorations, all of which were Class II. The main reason for failure was tooth fracture, followed by
resin composite fracture. The annual failure rate (AFR) for all restorations (Class I and II) was 1.2% for the bulk-
filled restorations and 1.0% for the resin composite-only restorations (p > 0.05). For the Class II restorations,
the AFR was 2.2% and 1.6%, respectively.
Conclusion: The 4-mm bulk-fill technique showed good clinical effectiveness during the 3-year follow-up.
Keywords: bulk fill, dental restorations, clinical, composite resin, nano, posterior, self-etching adhesive.
J Adhes Dent 2015; 17: 81–88. Submitted for publication: 03.08.14; accepted for publication: 10.12.14
doi: 10.3290/j.jad.a33502
a Professor, Dental School, Faculty of Medicine, Umeå University, Umeå, Swe-
den. Idea, hypothesis, design, clinical procedure, performed statistical evalu-
ation, wrote manuscript.
b Assistant Professor, Dental School, Faculty of Health Sciences, University of
Copenhagen, Denmark. Idea, design, hypothesis, clinical procedure, co-wrote
and proofread the manuscript, contributed substantially to discussion.
Correspondence: Professor JWV van Dijken, Dental School Umeå, Umeå Uni-
versity, 901 87 Umeå, Sweden. Tel: +46-90-785-6034, Fax.: +46 90 770580.
e-mail: jan.van.dijken@odont.umu.se
Resin composites (RC) have gradually replaced amal-
gam as a restorative material during the last de-
cade.59 Despite its increasing use in the posterior
region, several problems with resin-based materials,
mainly related to the reasons for failure (recurrent car-
ies, material and tooth fracture) still have not been
solved. During curing of the resin, a network of polymers
is formed, which becomes rigid due to increased cross
linking of the polymer chains. Decreasing mobility of the
network causes further shrinkage and results in a strain
on the RC and cavity margins. The resulting stress has
been associated with marginal deficiencies, enamel
fractures, cuspal movement, and cracked cusps, which
in turn may result in microleakage, post-operative sen-
sitivity, and secondary caries.1 It has been stated that
posterior Class II and especially Class I cavities with
a high C-factor will result in greater stresses due to a
larger number of bonded surfaces.28 However, the cor-
relation of interfacial stress and the clinical outcome is
weak, as shown in long-term follow-ups.14,16,50 Resin
composites with a lower modulus of elasticity or slower
curing rate may reduce the polymerization stress.36,60
Therefore, several modified insertion and light-curing
techniques have been introduced during the past few
years to decrease the marginal stress.22,24,39,47,56,60
So far, there is no evidence that these techniques im-
prove clinical efficacy.22,24 Extensive efforts have also
been made to develop low-shrinkage RCs by changing
filler amount, size, and shape, monomer structure or

82 The Journal of Adhesive Dentistry
van Dijken and Pallesen
chemistry, and by modifying the polymerization reac-
tion.34 Clinical data is limited, but acceptable durability
was reported in two 5-year follow-up studies.7,21
It has been claimed that polymerization shrinkage
may be decreased by the use of an incremental layering
technique, horizontal or oblique, by placing the material
in increments of 2 mm, followed by light curing of each
layer. However, in a fininte element analysis, Versluis et
al62 concluded that the oblique layering technique instead
produced the highest stresses. The use of a bulk-fill tech-
nique may result in lower shrinkage stress, but to obtain
optimal conversion in deeper layers, an incremental filling
technique is still required for conventional hybrid RC ma-
terials. The first marketed light-curing bulk-fill RC (QuiXfil,
Dentsply DeTrey; Konstanz, Germany), a very transluscent
material, showed acceptable clinical results in a 4-year
randomized clinical study.46 Recently, several new mater-
ials have been marketed within this new class of bulk-fill
resin-based composites, which can be cured in layers up
to 4 or 5 mm. They can be divided into two groups with
different mechanical properties, the low- and high-viscosity
materials.35 As opposed to the high-viscosity materials,
those with low viscosity must be covered with an occlusal
layer of conventional hybrid resin RC. For the first marketed
flowable bulk-fill composite resin, SDR (Dentsply DeTrey),
polymerization stress was claimed to be reduced directly
during curing. A polymerization modulator, a patented ure-
thane di-methacrylate, was chemically embedded in the
resin backbone, which resulted in a slower modulus de-
velopment, allowing stress reduction without decreasing
the conversion rate.3,27,33,35,36,38 Moorthy et al49 showed
that Class II cavities restored with the bulk-filled SDR RC to
within 2 mm of the occlusal enamel-dentin border resulted
in significantly reduced cuspal deflection compared to an
oblique technique. Significantly lower shrinkage stress was
observed for the flowable material than for a regular meth-
acrylate-based RC and several nanohybrid flowable RCs.33
Only one clinical study so far has examined the clinical
efficacy of the bulk-fill RCs and curing 4-mm-thick layers.26
Self-etching adhesives (SEA) are based on infiltration
and modification of the smear layer by acidic monomers
or by dissolving the smear layer and demineralizing the
underlying outer layer of dentin. The bond strength and
clinical performance of one-step SEAs have been ques-
tioned in the literature for many years, but recently, good
clinical durability has been reported for several new prod-
ucts.17,18,23,24,61 The successor of one of these SEAs,
the one-step SEA XenoV, showed good short-term durabil-
ity in a recent randomized clinical study.26 In the present
study, the latest version of the product (XenoV+), which
is claimed to exhibit optimized application features, was
tested in an extended investigation in combination with
the bulk-fill SDR and an improved version of the ormocer-
based nanohybrid RC Ceram X mono+.
The aim of this randomized controlled study was to
intra-individually compare the clinical effectiveness of
the flowable RC SDR placed in increments of 4 mm max-
imum (bulk fill) in large, deep Class I and Class II cavities
bonded with a one-step SEA. SDR was used to fill the cav-
ity 2 mm short of the occlusal cavosurface and was then
covered with a nanohybrid RC. The SDR restoration was
compared intra-individually with a restoration made only
of a nanohybrid RC placed and cured with a 2-mm layer-
ing technique. The null hypothesis tested was that there
would be no differences in clinical effectiveness between
restorations placed with the bulk-fill RC and those without.
MATERIALS AND METHODS
From October to December 2010, all adult patients at-
tending the Public Dental Health Service clinic at the
Dental School of Umeå and a private dental clinic in
Copenhagen who needed one or two pairs of similar
Class I or Class II restorations were asked to participate
in the follow-up. All invited patients participated in the
study. No participant was excluded because of high
caries activity, periodontal condition, or parafunctional
habits in order to mirror the whole patient population.
Pregnant patients were excluded. All patients were in-
formed about the background of the study, which was
approved by the ethics committee of the University of
Umeå (Dnr 07-152M) and followed recent CONSORT and
FDI recommendations.32 Reasons for placement of the
RC restorations were primary and secondary carious le-
sions, fracture of old fillings, or replacement for esthetic
or other reasons. In order to make an intra-individual
comparison possible, each patient received two or four
restorations as similarly sized and located as possible.
The majority of the cavities were deep and had ex-
tended sizes. There was no limitation on the thickness
of the remaining cusps. The cavity pairs in each indi-
vidual were randomly distributed in terms of restoration,
with either the experimental or the control restoration
asigned according to a predetermined scheme of ran-
domization. The participants did not know in which cav-
ity the experimental and control restoration were placed.
In the experimental cavity, an intermediate layer of the
SDR flowable RC (Dentsply DeTrey; Table 1) was placed
in the deepest parts, followed by an occlusal covering
layer of the nanohybrid RC Ceram X mono+ (Dentsply
DeTrey; subsequently termed Ceram X). The control res-
toration was filled with Ceram X (RC-only restoration).
All teeth were in occlusion and had at least one proxi-
mal contact with an adjacent tooth. Thirty-eight pairs of
Class I and 62 pairs of Class II restorations were placed
in 82 patients (44 men, 42 women) with a mean age of
52.4 years (20 to 86). The distribution of the involved
experimental teeth is shown in Table 2. The sample size
was calculated on the basis of previous sample size cal-
culations performed in similarly designed studies of pos-
terior restoration evaluations. The theoretical sample
size was set to 40 restorations per group to determine
significant differences in outcomes at the 95% confi-
dence level, with an alpha value = 0.05 and 80% power.
It has been possible to determine significant differences
between material groups in similarly designed intra-
individual comparison evaluations with this sample size
in previous studies.15,17,19 The number of participants
was increased to take possible drop-outs into account.

Vol 17, No 1, 2015 83
van Dijken and Pallesen
Clinical Procedure
Existing restorations and/or caries were removed
under constant water cooling. No bevels were pre-
pared. The operative field was carefully isolated with
cotton rolls and a suction device. For all Class II cavi-
ties, a thin metallic matrix was used and wedging was
done carfully with wooden wedges (KerrHawe Neos;
Bioggio, Switzerland). The cavities were cleaned by
thoroughly rinsing with water. None of the cavities re-
ceived Ca(OH)2 or other base materials. Application of
the one-step self-etching adhesive XenoV+ (Dentsply
DeTrey; Konstanz, Germany) in both cavities was per-
formed according to the manufacturer’s instructions
(Table 1). After gently agitating for 20 s, the solvent
was evaporated thoroughly for at least 5s. Curing was
then performed with a well-controlled high-power curing
unit (Smartlite PS, Dentsply DeTrey) for at least 10s.
For the experimental SDR restoration, the flow material
was dispensed directly into the cavity from the syringe
tip using slow, steady pressure, beginning at the deep-
est portion of the cavity and keeping the tip close to
the cavity floor. The tip was gradually withdrawn as
the cavity was filled. The material was available in
one semi-transluscent universal shade. It was placed
in bulk increments up to 4 mm as needed to fill the
cavity 2 mm short of the occlusal cavosurface. After
curing of the flow increment(s) for 20 s, the occlusal
part of the restoration was completed using RC Ceram
X. In the control cavity, the RC Ceram X was applied in
2-mm layers with an oblique layering technique, if pos-
sible. Selected resin composite instruments (Hu-Friedy;
Chicago, IL, USA) were used. The pairs of restorations
with each of the two restorative combinations were
placed by two experienced operators (JvD, UP). After
checking the occlusion/articulation and contouring with
finishing diamond burs, final polishing was performed
with the Shofu polishing system (Brownie, Shofu;
Kyoto, Japan) and finishing strips (GC finishing strips;
Tokyo, Japan).
Evaluation
At baseline (immediately after placing the restor-
ations) and after 1, 2, and 3 years the restorations
were assessed by the following parameters: anatomic
form, marginal adaptation, marginal discoloration,
surface roughness, color match, and secondary car-
ies by slightly modified USPHS criteria according to
van Dijken (Table 3).12 The follow-up exams were per-
formed blindly by both operators at their clinics and at
regular intervals by two calibrated evaluators. During
the evaluation sessions, evaluators did not know which
restorative material group the scoring concerned. For
each participant, caries risk and parafunctional habits
at baseline and during the follow-ups were estimated
by the treating clinician by means of clinical and socio-
demographic information routinely available at the an-
nual clinical examinations, eg, incipient caries lesions,
caries history, frequency and symptoms related to
bruxing activity.37,57
Statistical Analysis
The characteristics of the restorations were described
by descriptive statistics using cumulative frequency dis-
tributions of the scores. The experimental and control
restorative techniques were compared intra-individually
with non-parametric Friedman’s two-way ANOVA.58
Table 1 Resin composites and adhesive system used
Material Composition Type Application steps Manufacturer
SDR Filler: barium-alumino-fluoro-borosilicate glass, strontium
alumino-fluoro-silicate glass
Matrix: modified urethane dimethacrylate resin, ethoxylated
bisphenol-A dimethacrylate (EBPADMA), triethyleneglycol
dimethacrylate, camphorquinone, butylated hydroxyl toluene,
UV stabilizer, titanium oxide, iron oxide pigments
The SDR flow base
is covered with at
least 2 mm RC.
Apply in 4-mm
layers, light cure
20 s.
Dentsply
DeTrey;
Konstanz,
Germany
Ceram X
mono +
Filler: barium-aluminium-borosilicate glass (1.1-1.5 μm), meth-
acrylate functionalized silicone dioxide nano filler (10 nm)
Matrix: methacrylate modified polysiloxane, dimethacrylate
resin, fluorescent pigment, UV stabilizer, stabilizer, cam-
phorquinone, ethyl-4 (dimethylamino) benzoate, titanium
oxide pigments, aluminium silicate pigments
Nanohybrid: 76%
w/w filler, 57%
v/v filler, average
size of nanofillers
10 nm and nano
particles 2.3 nm
Apply in 2-mm
layers, light cure
20 to 30 s
Dentsply
DeTrey
XenoV+ 1-component one-
step self-etching
adhesive
Apply primer 20 s,
carefully air dry
for > 5 s, light cure
10 s
Dentsply
DeTrey
Table 2 Distribution of the experimental restorations
Surfaces Mandible Maxilla
Premolars Molars Premolars Molars
Class I 2 25 13 36 76
Class II 33 40 19 32 124
35 65 32 68 200

84 The Journal of Adhesive Dentistry
van Dijken and Pallesen
RESULTS
No postoperative symptoms were reported at baseline
or at the other recalls. At three years, 196 restorations
(74 Class I and 122 Class II) were evaluated. Two pairs
of restorations, two Class I and two Class II cavities
(drop-out rate 2%), could not be observed because one
patient moved away and another died, both during the
first year of the evaluation.
During the 3-year follow-up, 7 restorations (3.6%)
failed, 4 SDR-CeramX mono+ and 3 CeramX mono+ only
restorations. No Class I restoration failed. Two defects
were observed: 1 small chip fracture which was polished
and a restoration with a porosity, which was filled in. The
year of and reason for failure of the failed restorations
are given in Table 4. The scores at baseline and 1, 2,
and 3 years for all the evaluated restorations are given
as relative frequencies in Table 5. The modified USPHS
scores of the Class II and Class I restorations separately
are given in Tables 6 and 7, respectively. For all restor-
ations (Class I and II), the SDR/CeramX mono+ annual
failure rate (AFR) was 1.2% and the CeramX mono+ AFR
was 1.0%. For the Class I restorations, the AFR was 0%
in both groups. For the Class II restorations, the SDR/
CeramX mono+ group showed an AFR of 2.2% and the
CeramX mono+ group an AFR 1.6%. The overall differ-
ences between the two experimental restorations for
the evaluated variables in both cavity classes were not
significant. Six of the seven failures were observed in fe-
male participants. Eighteen participants were estimated
as having high caries risk and sixteen showed mild to
severe parafunctional habits during the observation
period. The two carious lesions observed were found in
high caries-risk participants. Four of the five fractures
(cusp and material) occurred in bruxing participants. No
further statistical analysis was performed due to the low
failure rate.
Table 3 Modified USPHS criteria for direct clinical evaluation (modified after van Dijken12)
Category Score Criteria
acceptable unacceptable
Anatomical
form
0
1
2
3
The restoration is contiguous with tooth anatomy
Slightly under- or over-contoured restoration; marginal ridges slightly undercon-
toured; contact slightly open (may be self-correcting); occlusal height reduced locally
Restoration is undercontoured, dentin or base exposed; contact is faulty, not self-
correcting; occlusal height reduced; occlusion affected
Restoration is missing partially or totally; fracture of tooth structure; shows trau-
matic occlusion; restoration causes pain in tooth or adjacent tissue
Marginal
adaptation
0
1
2
3
4
Restoration is contiguous with existing anatomic form, explorer does not catch
Explorer catches, no crevice is visible into which explorer will penetrate
Crevice at margin, enamel exposed
Obvious crevice at margin, dentin or base exposed
Restoration mobile, fractured or missing
Color
match
0
1
2
3
4
Very good color match
Good color match
Slight mismatch in color, shade or translucency
Obvious mismatch, outside the normal range
Gross mismatch
Marginal
discoloration
0
1
2
3
No discoloration evident
Slight staining, can be polished away
Obvious staining cannot be polished away
Gross staining
Surface
roughness
0
1
2
3
Smooth surface
Slightly rough or pitted
Rough, cannot be refinished
Surface deeply pitted, irregular grooves
Caries 0
1
No evidence of caries contiguous with the margin of the restoration
Caries is evident contiguous with the margin of the restoration
Table 4 Failed class II restorations during the 3-year
evaluation, tooth type, year of and reason for failure
Mater-
ials
Tooth
type
Year of
failure
Reason for
failure
XenoV+/
SDR/
CeramX
mono+
P
P
M
M
2
2
2
3
Tooth fracture
Caries and tooth fracture
Tooth fracture and resin com-
posite fracture
Caries
XenoV+/
CeramX
mono+
M
M
M
1
3
3
Tooth fracture
Tooth fracture
Resin composite fracture

Vol 17, No 1, 2015 85
van Dijken and Pallesen
DISCUSSION
In the present randomized controlled study, restorations
placed with the 4-mm layering technique using flowable
bulk-fill material capped with a nanohybrid RC showed
no significant difference in clinical efficacy compared
to the restorations placed with a conventional 2-mm
layering technique. The durability of restorations placed
with the bulk-fill technique in the 3-year follow-up was
clinically acceptable and confirms the results of an
earlier evaluation with the predecessors of the SEA and
RC used in the present study in combination with SDR.
Table 5 Scores for the evaluated XenoV+/ SDR-Ce-
ramX mono+ and XenoV+/ CeramX mono+ Class I and
II restorations at baseline (n = 76 and 124), 1, 2, and 3
years (n = 74 and 122) given as relative frequencies (%)
01234
Anatomical form
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
95.0
98.0
95.0
98.0
94.9
94.9
94.9
97.0
5.0
2.0
4.0
2.0
2.0
4.1
2.0
0
0
0
1.0
0
0
0
0
1.0
0
0
0
0
3.1
1.0
3.1
2.0
Marginal adaptation
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
99.0
100
97.0
99.0
92.9
96.0
87.8
92.9
1.0
0
2.0
1.0
4.0
2.0
9.1
4.1
0
0
0
0
0
1.0
0
1.0
0
0
1.0
0
1.0
0
0
0
0
0
0
0
2.1
1.0
3.1
2.0
Color match
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
60.0
65.0
54.6
63.3
48.4
54.6
45.3
53.7
38.0
33.0
35.1
31.6
44.2
39.2
47.3
41.1
2.0
2.0
10.3
5.1
7.4
6.2
7.4
5.2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Marginal
discoloration
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
96.9
99.0
89.5
95.9
82.1
90.5
0
0
2.1
1.0
8.4
4.1
15.8
6.3
0
0
1.0
0
2.1
0
2.5
3.2
0
0
0
0
0
0
0
0
Surface roughness
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
99.0
99.0
97.9
100
100
95.9
92.6
97.9
1.0
1.0
2.1
0
0
4.1
7.4
2.1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Caries
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
100
100
99
100
98
100
0
0
0
0
1
0
2
0
C= CeramX mono+.
Table 6 Scores at baseline (n = 124) and after 1, 2,
and 3 years (n = 122) for the evaluated Class II restor-
ations of XenoV+/ SDR-CeramX mono+ and XenoV+/
CeramX mono+ given as relative frequencies (%)
01234
Anatomical form
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
91.9
96.8
91.8
96.7
91.8
91.8
91.8
95.1
8.1
3.2
6.6
3.3
3.3
6.6
3.3
0
0
0
1.6
0
0
0
0
1.6
0
0
0
0
4.9
1.6
4.9
3.3
Marginal adaptation
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
98.4
100
95.1
98.4
90.2
93.5
85.2
88.5
1.6
0
3.3
1.6
4.9
3.3
9.9
6.6
0
0
0
0
0
1.6
0
1.6
0
0
1.6
0
0
0
0
0
0
0
0
0
4.9
1.6
4.9
3.3
Color match
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
59.7
62.9
51.6
63.9
48.3
51.7
41.4
50.0
37.1
35.5
36.7
32.8
44.8
41.6
50.0
44.8
3.2
1.6
11.7
3.3
6.9
6.7
8.6
5.2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Marginal
discoloration
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
95.0
98.4
84.5
93.3
72.4
84.5
0
0
3.3
1.6
12.1
6.7
24.1
10.3
0
0
1.7
0
3.4
0
3.5
5.2
0
0
0
0
0
0
0
0
Surface roughness
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
98.4
98.4
98.3
100
100
96.7
89.7
96.5
1.6
1.6
1.7
0
0
3.3
10.3
3.5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Caries
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
100
100
98.4
100
96.7
100
0
0
0
0
1.6
0
3.3
0
C= CeramX mono+.

86 The Journal of Adhesive Dentistry
van Dijken and Pallesen
No difference was observed between the restorations
with and without SDR. The hypothesis was therefore
accepted. The results show that it is possible to use
clinically thicker increments, which may certainly have
advantages in many clinical situations, such as deep
cavities and other sites that are difficult to reach with
the curing unit.
One of the disadvantages of light-curing RCs is their
limited depth of cure, with the associated risk of undercur-
ing the bottom part of each too-thick layer. The maximum
increment thickness has generally been defined as ap-
proximately 2 mm, depending on the limited penetration of
light through the material.42,43,52,55 A layering technique is
therefore necessary to obtain sufficient conversion, which
in turn is mandatory for obtaining acceptable physical-me-
chanical properties and biocompatibility of the resin-based
material.29,36,40,48 The layering technique is sensitive and
bear certain risks, such as incorporating air and/or con-
tamination between the layers. Versluis et al62 indicated
that incremental layering induced high stresses at the inter-
facial margins and that bulk filling should be preferred. It
is crucial that bulk-fill materials possess good curing abil-
ity, otherwise inferior mechanical properties and increased
monomer leakage will be the result. Several in vitro studies
have confirmed that the bulk-fill material tested could be
cured in 4-mm layers at irradiation times up to 20 s. This
was shown by using the ISO 4049 “scrape test” as well
as microhardness tests and Fourier transformed infrared
spectroscopy.3,5,7,10 Flury et al30 stated recently that for
bulk-fill materials, the ISO 4049 method overestimated
depth of cure compared to that determined by Vickers hard-
ness profiles.30 Using Vickers hardness profiles, Alrahlah
et al2 confirmed the depth of cure claims of manufacturers
of five bulk-fill RCs and showed that these materials had an
acceptable post-cure depth. Variations in the depth of cure
can be caused by light scattering at particle interfaces and
light absorbance by photoinitiators and pigments. Ilie et
al35 explained the enhanced depth of cure of the flowable
bulk-fill RC by an increased translucency due to decreased
filler load and increased filler size of the material. This
reduces light scattering and improves light penetration.35
Inadequate conversion of a resin-based material will result
in higher monomer leakage and decreased biocompatibil-
ity due to higher cytotoxicity. A recently published in vitro
study investigated the cytotoxicity of flowable SDR by MTT
assay.53 Those authors showed that exposed cells main-
tained their mesenchymal phenotype, adequate viability,
and no significant aptosis.53
In vitro studies revealed that several mechanical prop-
erties, eg, flexural strength and creep, were similar for
bulk-fill RCs and nanohybrid RCs.35,36 For other proper-
ties, such as hardness and modulus of elasticity, the
bulk-fill materials were classified between the hybrid RCs
and the flowable RCs.35,36 The concern that application
of thicker layers of the flowable bulk-fill material applied in
deep cavities would result in increased shrinkage stress
was not confirmed in vitro; in fact, the bulk-fill material re-
vealed the lowest shrinkage stress compared to flowable
and non-flowable nanohybrid and microhybrid RCs and a
silorane-based RC.33 This was confirmed by Moorthy et
al,49 who showed that the SDR base significantly reduced
cuspal deflection in Class II cavities in premolars com-
pared with a conventional RC; in that study, the prepared
cavities were restored using an oblique incremental filling
technique. No associated change in cervical microleak-
age was recorded.49 The clinical relevance of this has to
date not been shown.16 Adequate marginal adaptation
Table 7 Scores at baseline (n = 76), 1, 2, and 3
years (n = 74) for the evaluated Class I restorations of
XenoV+/ SDR-CeramX mono+ and XenoV+/ CeramX
mono+ given as relative frequencies (%)
01234
Anatomical form
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
100
100
100
100
100
100
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Marginal adaptation
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
100
100
97.3
100
91.9
100
0
0
0
0
2.7
0
8.1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Color match
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
60.5
68.5
59.5
62.2
48.7
59.5
51.4
59.5
39.5
28.9
32.4
29.7
43.2
35.1
43.2
35.1
0
2.6
8.1
8.1
8.1
5.4
5.4
5.4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Marginal discolor-
ation
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
100
100
97.3
100
97.3
100
0
0
0
0
2.7
0
2.7
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Surface roughness
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
97.3
100
100
100
97.3
100
0
0
2.7
0
0
0
2.7
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Caries
XenoV+/SDR/C baseline
XenoV+/C baseline
XenoV+/SDR/C 1 year
XenoV+/C 1 year
XenoV+/SDR/C 2 year
XenoV+/C 2 year
XenoV+/SDR/C 3 year
XenoV+/C 3 year
100
100
100
100
100
100
100
100
0
0
0
0
0
0
0
0
C= CeramX mono+.

Vol 17, No 1, 2015 87
van Dijken and Pallesen
in vitro has also been reported for the flowable base ma-
terial.9,54 We found that the 1.4% annual failure rate for
the SDR restorations was not significantly different from
the 1.0% for the control nanohybrid RC-only restorations.
During the past few years, we have observed AFRs vary-
ing between 0.9% and 3.3% in the majority of our rand-
omized clinical studies on posterior restorations in which
different microhybrid and nanohybrid RCs and adhesive
systems were evaluated; similar AFRs were found in a
recent practice-based study.20-25,41,44,51 The good clin-
ical efficacy in the present 3-year follow-up situated the
SDR flowable bulk-fill RC technique between the lower AFR
materials. Catastrophic failure rates have been observed
for a few restorative materials evaluated after 3 years. A
hydroxyl-releasing RC showed an 8.7% AFR and a calcium
aluminate cement a 24.2% AFR, indicating the necessity
of 3-year follow-ups of new material groups.15,19
All failures in the present study were observed in Class
II restorations. AFRs for the Class II restorations were
therefore higher than the overall AFR, with 2.2% and 1.6%,
respectively. The low failure rate of Class I restorations
has been reported in many clinical investigations.16 Com-
paring AFRs, recent studies state that the durability of new
posterior RC restorations is the same as that reported in
reviews from earlier studies around the turn of the cen-
tury.6,10,45 However, it is difficult to compare earlier stud-
ies of posterior RCs with recent ones due to the fact that
the former comprised much larger numbers of Class I res-
torations than the latter, as shown in a current review.25
The value of inclusion of Class I restorations in posterior
RC trials should therefore be questioned.
The main reason of failure in this study was cusp frac-
ture. This is in contrast to other studies, in which caries
and/or material fracture were the main reasons for fail-
ure of RCs. Of seven failures, three were cusp fracture
only and two were cusp fracture in combination with res-
toration fracture or caries. There are few reports in the
literature describing the occurrence of tooth fractures.31
Bader et al4 reported the occurrence of cusp fracture to
be 5 teeth per 100 adults annually. Heft et al31 reported
an incidence rate of 14 teeth with cusp/incisal edge frac-
tures per 100 subjects per 24 months.31 Cusp fractures
are still a significant dental health problem, especially in
older adults. In many cases, these are caused by the con-
ventional preparation technique for amalgam restorations
with large undercuts in posterior teeth, in order to obtain
macromechanical retention.13 A continuous occlusal load-
ing of the weakened cusps will result initially in horizon-
tal crack formation followed by cusp fractures. Adhesive
bonding of the resin composite material to the cavity walls
with amphiphilic bonding systems may alleviate this prob-
lem. In the present study, almost all included cavities
were replacements of older restorations which had been
placed in cavities with macromechanical retention, which
increases the risk of cusp fractures. High frequencies of
cusp fractures have also be observed in earlier studies
of restorative materials with increased water absorption
over longer periods. This resulted in increased expansion
of the restorative materials, followed by crack formation
in the buccal or lingual cusps and cusp fractures.15,19
However, it can be assumed that this was not the case
for the bulk-fill material used here, because we observed
no failures due to cusp fractures in teeth with SDR restor-
ations in a similar 3-year clinical follow up.26
CONCLUSION
The new bulk-fill technique showed acceptable clinical
results and was similar to the conventional layering
technique during the 3-year evaluation period. Annual
failure rates were 1.0% for the conventionally filled
and 1.4% for the bulk-filled restorations. Good surface
characteristics, marginal adaptation, and color stability
as well as a low frequency of secondary caries and resin
composite fracture rate were observed.
ACKNOWLEDGMENTS
The support from the County Council of Västerbotten and Dentsply
DeTrey is gratefully acknowledged.
REFERENCES
1. Abbas G, Fleming GJ, Harrington E, Shortall AC, Burke FJ. Cuspal move-
ment and microleakage in premolar teeth restored with a packable com-
posite cured in bulk or increments. J Dent 2003;31:437-444.
2. Alrahlah A, Silikas N, Watts DC. Post-cure depth of cure of bulk fill den-
tal resin-composites. Dent Mater 2014;30:149-154.
3. Alshali RZ, Silikas N, Satterthwaite JD. Degree of conversion of bulk-fill
compared to conventional resin-composites at two time intervalls. Dent
Mater 2013;29:e213-e217.
4. Bader JD, Martin JA, Shugars DA. Preliminary estimates of the incidence
and consequences of tooth fracture. JADA 1995;126:1650-1654.
5. Benetti AR,Havndrup-Pedersen C,Honoré D, Pedersen MK, Pallesen U.
Bulk-fill resin composites: Polymerization contraction, depth of cure,
and gap formation. Oper Dent 2014; [Epub ahead of print] doi:
10.2341/13-324-L.
6. Brunthaler A, König F, Lucas T, Sperr W, Schedle A. Longevity of di-
rect resin composite restorations in posterior teeth. Clin Oral Invest
2003;7:63-70.
7. Burke FJT, Crisp R. Practice-based five-year evaluation of a low shrink-
age stress composite [abstract]. J Dent Res 2014;93(special issue B):
247.
8. Campodonico CE, Tantbirojn D, Olin PS, Versluis A. Cuspal deflec-
tion and depth of cure in resin-based composite restorations filled by
using bulk, incremental and transtooth-illumination techniques. JADA
2011;142:1176-1182.
9. Campos EA, Ardu S, Lefever D, Jassé FF, Bortolotto E, Krejci I. Marginal
adaptation of Class II cavities restored with bulk-fill composites, J Dent
2014;42:575-581.
10. Chadwick B, Dummer P, Dunstan F, Gilmour ASM, Joner RJ, Phillips CJ,
Rees J, Richmond S, Stevens J, Treasure ET. The longevity of dental
restorations. A systematic review. Report 19. NHS Centre for reviews
and dissemination: University of York, York, England, 2001a.
11. Czasch P, Ilie N. In vitro comparison of mechanical properties and de-
gree of cure of bulk fill composites. Clin Oral Invest 2012;17:227-235.
12. Dijken JWV van. A clincial evaluation of anterior conventional, microfiller
and hybrid composite resin fillings. A six-year follow-up study. Acta
Odont Scand 1986;44:357-367.
13. Dijken JWV van. A six-year follow-up of three dental alloy restorations
with different copper contents. Swed Dent J 1991;15:259-264.
14. Dijken JWV van. Direct resin composite inlays/onlays: an 11-year follow-
up. J Dent 2000;28:299-306.
15. Dijken JWV van. Three-year performance of a calcium-, fluoride- and
hydroxyl ions releasing resin composite. Acta Odontol Scand 2002;60:
155-159.
16. Dijken JWV van. Durability of resin composite restorations in high
C-factor cavities. A 12-year follow-up. J Dent 2010;38:469-474.

88 The Journal of Adhesive Dentistry
van Dijken and Pallesen
17. Dijken JWV van. A 6-year prospective evaluation of a one-step HEMA-
free self etching adhesive in Class II restorations. Dent Mater
2013;29;1116-1122.
18. Dijken JWV van. A randomized controlled 5-year prospective study of two
HEMA free adhesives, a 1-step self etching and a 3-step etch-and-rinse,
in non-carious cervical lesions. Dent Mater 2013;29:e271-e280.
19. Dijken JWV van, Sunnegårdh-Grönberg K. A two-year clinical evaluation
of a new calcium aluminate cement in Class II cavities. Acta Odontol
Scand 2003;61:235-240.
20. Dijken JWV van, Sunnegårdh-Grönberg K. Fiber-reinforced packable resin
composites in Class II cavities. J Dent 2006;34:763-769.
21. Dijken JWV van, Lindberg A. Clinical effectiveness of a low shrinkage
resin composite. A five-year study. J Adhes Dent 2009;11:143-148.
22. Dijken JWV van, Pallesen U. Clinical performance of a hybrid resin com-
posite with and without an intermediate layer of flowable resin compos-
ite: A 7-year evaluation. Dent Mater 2011;27:150-156.
23. Dijken JWV van, Pallesen U. Four-year clinical evaluation of Class II
nano-hybrid resin composite restorations bonded with a one-step self-
etch and a two-step etch-and-rinse adhesive. J Dent 2011;39:16-25.
24. Dijken JWV van, Pallesen U. A 7-year randomized prospective study of
a one-step self-etching adhesive in -carious cervical lesions. The effect
of curing modes and restorative material. J Dent 2012;40:1060-1067.
25. Dijken JWV van, Pallesen U. A six-year prospective randomized study of
a nano-hybrid and a conventional hybrid resin composite in Class II res-
torations. Dent Mater 2013;29:191-198.
26. Dijken JWV van, Pallesen U. A randomized controlled three year evalu-
ation of “bulk-filled” posterior resin restorations based on stress de-
creasing resin technology. Dent Mater 2014;30:e229-e237.
27. El-Damanhoury H, Platt J. Polymerisation shrinkage stress kinet-
ics and related properties of bulk-fill resin composites. Oper Dent
2014;39:374-382.
28. Feilzer AJ, de Gee AJ, Davidson CL. Setting stress in composite resin
in relation to configuration of the restoration. J Dent Res 1987;66:
1636-1639.
29. Ferracane JL, Mitchem JC, Condon JR, Wear Todd R. Marginal break-
down of composites with various degrees of cure. J Dent Res 1997;76:
1508-1516.
30. Flury S, Hayoz S, Peutzfeldt A, Hüsler J, Lussi A. Depth of cure of resin
composites. Is the ISO 4049 method suitable for bulk fill materials?
Dent Mater 2012;28:521-528.
31. Heft MW, Gregg HG, Dolan TA, Foerster U. Restoration fractures, cusp
fractures and root fragments in a diverse sample of adults: 24 month
incidence. JADA 2000;131:1459-1464.
32. Hickel R, Roulet J-F, Bayne S, Heintze SD, Mjör IA, Peters M, Rous-
son V, Randall R, Schmalz G, Tyas M, Vanherle G. Recommendations
for conducting controlled clinical studies of dental restorative materials.
J Adhes Dent 2007; 9:121-147.
33. Ilie N, Hickel R. Investigations on a methacrylate-based flowable com-
posite based on the SDRTM technology. Dent Mater 2011;27:348-355.
34. Ilie N, Hickel R. Resin composite restorative materials. Austr Dent J
2011;56:59-66.
35. Ilie N, Bucuta S, Draenert M. Bulk-fill resin-based composites: an
in vitro assessment of their mechanical performance. Oper Dent
2013;38:618-625.
36. Ilie N, Keßler A, Durner J. Influence of various irradiation processes on
the mechanical properties and polymerisation kinetics of bulk-fil resin
based composites. J Dent 2013;41:695-702.
37. Isokangas P, Alanen P, Tiekso J. The clinician’s ability to identify caries
risk subjects without saliva tests – a pilot study. Community Dent Oral
Epid 1993:21:8-10.
38. Jin X, Bertrand S, Hammesfahr PD. New radically polymerizable resins
with remarkably low curing stress. J Dent Res 2009;88(special issue A):
1651.
39. Kanca J, Suh BI. Pulse activation: reducing resin-based composite
contraction stresses at the enamel cavosurface margins. Am J Dent
1999;12:107–112.
40. Kovaric RE, Ergle JW. Fracture toughness of posterior composite resins
fabricated by incremental layering. J Prosth Dent 1993;69:557-560.
41. Lindberg A, van Dijken JWV, Lindberg M. A 3-year evaluation of a new
open sandwich technique in class II cavities. Am J Dent 2003;16:
33-36.
42. Lindberg A, Peutzfeldt A, van Dijken JWV. Effect of power density of
curing unit, exposure duration, and light guide distance on composite
depth of cure. Clin Oral Inv 2005;9:71-76.
43. Lindberg A, Enami N, van Dijken JWV. A Fourier Transform Raman
spectroscopy analysis of the degree of conversion of a universal hybrid
resin composite cured with light-emitting diode curing units. Swed Dent
J 2005;29:105-112.
44. Lindberg A, van Dijken JWV, Lindberg M. Nine-year evaluation of a poly-
acid-modified resin composite open sandwich technique in class II cavi-
ties. J Dent 2006;35:124-129.
45. Manhart J, Chen H, Hamm G, Hickel R. Buonocore Memorial Lecture.
Review of the clinical survival of direct and indirect restorations in pos-
terior teeth of the permanent dentition. Oper Dent 2004;29:481-508.
46. Manhart J, Chen H-Y, Hickel R. Clinical evaluation of the posterior com-
posite QuiXfil in class I and II cavities: 4-year follow-up of a randomized
controlled trial. J Adhes Dent 2009;12:1-7.
47. Mehl A, Hickel R, Kunzelmann K. Physical properties. Gap formation
of light-cured composites with and without “softstart-polymerization”.
J Dent 1997;25:321-330.
48. Michelsen VB, Kopperud HB, Lygre GB, Björkman L, Jensen E, Klever IS,
Svahn J, Lygre H. Detection and quantification of monomers in unstimu-
lated whole saliva after treatment with resin-based composite fillings in
vivo. Eur J Oral Sci 2012;120:89-95.
49. Moorthy A, Hogg CH, Dowling AH, Grufferty BF, Benetti AR, Flem-
ingGJP. Cuspal deflection and microleakage in premolar teeth restored
with bulk-fill flowable resin-based composite base materials. J Dent
2012;40:500-505
50. Pallesen U, Qvist V. Composite resin fillimgs and inlays. An 11-year
evaluation. Clin Oral Invest 2003;7:71-79.
51. Pallesen U, Dijken JWV van, Hallonsten A-L, Halken J, Höigaard R.
Longevity of posterior resin composite restorations in permanent teeth
in Public Dental Health Service. A prospective 8-year follow-up. J Dent
2013,41:27-306.
52. Pilo R, Oelgiesser D, Cardash HS. A survey of output intensity and po-
tential for depth of cure among light-curing units in clinical use. J Dent
1999;27:235-241.
53. Rodríguez-Lozano FJ, Serrano-Belmonte I, PérezCalvo CJ, Coronado-
Parra MT, Bernabeu.Esclapez A, Moraleda JM. Effects of two low-
shrinkage composites on dental stem cells (viability, cell damaged or
apotosis and mesenchymal markers expression). J Mater Sci Mater
Med 2013;24:979-988.
54. Roggendorf MJ, Krämer N, Appelt A, Naumann M, Frankenberger R.
Marginal quality of flowable 4-mm base vs.conventionally layered resin
composite. J Dent 2011;39:643-647.
55. Sakaguchi RL, Douglas WH, Peters MC. Curing light performance and
polymerization of composite restorative materials. J Dent 1992;20:
183-188.
56. Sakaguchi RL, Berge HX. Reduced light energy density decreases post-
gel contraction while maintaining degree of conversion in composites.
J Dent 1998;26:695–700.
57. Seppä L, Hausen H, Pöllänen L, Helasharju K, Karkkainen S. Past
caries recording made in Public Dental Clinics as predictors of caries
prevalence in early adolescence. Community Dent Oral Epid 1989;17:
277-281.
58. Siegel S. Nonparametric Statistics. New York: McGraw-Hill, 1956:
166-172.
59. Sunnegårdh-Grönberg K, van Dijken JWV, Funegårdh U, Lindberg A,
Nilsson M. Selection of dental materials and longevity of replaced res-
torations in Public Dental Health clinics in northern Sweden. J Dent
2009;37:673-678.
60. Unterbrink GL, Muessner R. Influence of a light intensity on two restora-
tive systems. J Dent 1995;23:183–189.
61. Van Landuyt KL, De Munck J, Ermis B, Peumans M, Van Meerbeek B.
Five-year clinical performance of a HEMA-free one-step self-etch
adhesive in noncarious cervical lesions. Clin Oral Invest 2014;18:
1045-1052.
62. Versluis A, Douglas WH, Cross M, Sakaguchi RL. Does an incremental
filling technique reduce polymerization shrinkage stresses? J Dent Res
1996;75:871-878.
Clinical relevance: The new bulk-fill technique
showed acceptable clinical results and was similar to
the conventional layering technique during the 3-year
evaluation period.