In-Vitro Analysis of Gap Formation between Tooth Restoration Interfaces Using Bulk Fill and Incremental Fill Composites

Abstract

creative commons attribution noncommercial License. Which allows others to remix, tweak, and build upon the work non commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. Abstract Aim: To identify a composite system with minimum Gap formation Materials and Methods: Standard class I cavity was prepared in 12 intact human premolars. Samples were divided into two groups (n=6), according to the materials used one Bulk Fill composites (Sonicfill) and one increment fill composites (Spectrum TPH). Thermocycling was done and then the samples were sectioned buccolingually. The samples were then examined under scaning electron microscope for gap formation. Statistical Analysis: Kruskal wallis test and Post hoc pairwise comparison of Gap formation using Mann Whitney U test Results: Bulk fill composite showed the best adaptive capacity as compared to incremental fill composite. Conclusion: Bulk-fill composite showed better adaptability and less gap formation than incremental composite.

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International Journal of Dental Science and Innovative Research (IJDSIR)
IJDSIR : Dental Publication Service
Available Online at: www.ijdsir.com
Volume – 3, Issue – 3, June - 2020, Page No. : 05 - 08
Corresponding Author: Nimra Iqbal, ijdsir, Volume – 3 Issue - 3, Page No. 05 - 08
Page 5
ISSN: 2581-5989
PubMed - National Library of Medicine - ID: 101738774
In-Vitro Analysis of Gap Formation between Tooth Restoration Interfaces Using Bulk Fill and Incremental Fill
Composites
1Nimra Iqbal, MDS, Conservative Dentistry and Endodontics, ITS Dental College and Hospital, Greater Noida.
Corresponding Author: Nimra Iqbal, MDS, Conservative Dentistry and Endodontics, ITS Dental College and Hospital,
Greater Noida.
Citation of this Article: Nimra Iqbal, “In-Vitro Analysis of Gap Formation between Tooth Restoration Interfaces Using
Bulk Fill and Incremental Fill Composites”, IJDSIR- June - 2020, Vol. – 3, Issue -3, P. No. 05 - 08.
Copyright: © 2020, Nimra Iqbal, et al. This is an open access journal and article distributed under the terms of the
creative commons attribution noncommercial License. Which allows others to remix, tweak, and build upon the work non
commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
Type of Publication: Original Research Article
Conflicts of Interest: Nil
Abstract
Aim: To identify a composite system with minimum Gap
formation
Materials and Methods: Standard class I cavity was
prepared in 12 intact human premolars. Samples were
divided into two groups (n=6), according to the materials
used one Bulk Fill composites (Sonicfill) and one
increment fill composites (Spectrum TPH).
Thermocycling was done and then the samples were
sectioned buccolingually. The samples were then
examined under scaning electron microscope for gap
formation.
Statistical Analysis: Kruskal wallis test and Post hoc
pairwise comparison of Gap formation using Mann
Whitney U test
Results: Bulk fill composite showed the best adaptive
capacity as compared to incremental fill composite.
Conclusion: Bulk-fill composite showed better
adaptability and less gap formation than incremental
composite.
Keywords: bulk fill, composites, Gap formation,
incremental fill
Introduction
Light cured composites are the material of choice for
direct restorations because they offer prolonged
manipulation time and on command curing.1 Composite
has shown a level of success as a restorative material.
There have been continuous efforts to improve its physical
and mechanical properties and the operating techniques
used to apply it.2 Adhesive bonding to tooth structure has
been an integral part of modern restorative dental practice
that obviously improves the biomechanical and esthetic
quality outcomes of restoration.3 Gap Formation occurs, if
the interfacial stresses exceeds those that can be supported
by the adhesive layer.4 Less contraction stress around
cavity walls and margins will generate, if depth of cure of
resin composite is limited, thus possibly disguising an
improved marginal adaptation due to poor
polymerization.5

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Various methods of composite placement have been
employed; the incremental curing technique being one of
them.6 However, this technique has many disadvantages: It
is difficult to place the multiple increments leading to an
increase in the arduousness of the task and the time it
takes to complete it. If not performed properly, placing
multiple layers can result in polymerization shrinkage and
marginal leakage.7
In light of this, a group of new products were recently
introduced, known as ―BulkFill composites. These
materials are recommended for insertion in a maximum 4-
mm bulk due to their high reactivity to light curing. The
rationale of the bulk-fill resins is to reduce clinical steps
by filling the cavity in ―single‖ increment, leading to a
reduced porosity and a uniform consistency for the
restoration, this will reduce the clinical time taken and
also the cost.8
The use of the bulk-fill technique undoubtedly simplifies
the restorative procedure and saves clinical time in cases
of deep, wide cavities. However, the data available for
these materials are currently limited, and therefore further
laboratory studies are required in order to provide insight
into likely clinical outcomes.9
Materials and Method
12 intact human Premolars were selected randomly for the
study. Standardized Class I cavity to the depth of 4mm
was prepared in each tooth, (distance of margins to the
proximal surface will be 1.6mm) using standard ¼ round
bur under profuse water cooling. The depth of Class I
cavity prepared was 4mm checked with Williams probe.
The samples were then divided into two groups of 6 teeth
each according to the type of material.
The teeth were etched using 3M ESPE Scotch Bond
multipurpose etchant for 20 sec following which the
specimens were washed with distilled water for 15-20s
and further blot dried for 20s. Then Adper Single Bond
adhesive (3M ESPE) was applied to and scrubbed on the
surface for 20s to create a good hybridization of the etched
area. Next, the adhesive was air-thinned until the entire
carrier was evaporated. It was then light-cured for 20s All
the cavities prepared were then restored with different
materials.
Group A (n=6):The teeth were restored with Sonicfil
Composite
Group B (n=6):The teeth were restored with Spectrum
TPH Composite
Specimens were then subjected to a thermocycling
regimen of 500 thermal cycles by alternating immersion in
water by +5 to ±8°c and +55 to ±8°c with a dwell time of
2 min and transfer time of 5 sec in each bath. All
specimens were sectioned buccolingually with diamond
disc. Among two sections from each sample one was
taken to check the Gap Formation. Which makes it 6
samples per group. A total of 12 samples were subjected
to SEM analysis
Each specimen was taken to vaccum desiccators and
sputter coated with gold palladium and then was examined
under Scanning Electron Microscope for Gap Formation
under 1500X magnification. The dentin restoration
interface was analysed at 7 sites in the buccolingual
sections. The size of the gaps in different locations was
measured and means gap was calculated for each
investigated material. The results were calculated,
tabulated and subjected to statistical analysis
Statistical Analysis
The Statistical analysis was performed by using SPSS
program (Statistical Package for Social Sciences) for
Windows, version 17.0. Continuous variables are

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presented as mean ± SD. Data were checked for
normality before statistical analysis using Shaipro Wilk
test.
When intergroup comparison of Mean Gap Formation was
done using Kruskal Wallis test, then the difference was
found to be statistically significant between all Groups
having the p value ˂0.05
Post hoc pairwise comparison of Mean Gap formation
among two study groups was done using Mann Whitney U
test.
Results
The results of the study showed that the bulk-fill
composite demonstrated less gap formation than
incrementally filled composite.
Table 1: Mean and Standard Deviation values for Gap
Formation for all groups
Gap Formation
Groups
Mean
N
Std. Deviation
Gr A
2.2403
6.0000
0.2181
Gr B
5.2977
6.0000
1.4840
Pa value
<0.0001
Kruskal wallis Test
Group A (Sonicfill) Group C (Sperctrum Tph)
Fig. 1: Scanning Electron Microscope View Of Samples
Of Bulk Fill And Incremental Fill Groups For Gap
Formation.
Discussion
Self-cured traditional composites which were prepared as
two components mixed just before use, resulting in
inadvertent air incorporation leaving pores as mechanical
defects that were extremely deleterious to strength.10
Then incrementally placed composite resins came , but the
big challenge faced by them was the , bond failures
between increments, incorporation of voids or
contamination between composite layers, because of
limited access in conservative preparations leads to
difficulty in placement, and the increased time required to
place and polymerize each layer.11
Then came bulk fill composites which were having less
incorporation of voids between composite layer than any
other composite placement technique, require less chair
side time thus making the restorative process comfortable
to the patient.
In this study Bulk Fill composite demonstrated
Significantly better results than the Incremental Fill
Composite. This is because that Bulk Fill Composites
demonstrated enhanced flowability leading to good
adaptation, elasticity and Low Polymerisation Shrinkage
stress which reduces microleakage, reduced postoperative
sensitivity and secondary caries and can be cured in bulk
as they are highly translucent which in turn allow light to
sufficiently penetrate to the bottom of single increment
layer. The mean score values for Gap formation for Group
A was 2.2403µ and Group B was 5.2977µ, and Standard
Deviation for Group A 0.2181 and Group B was 1.4840
(Table 1).
When intergroup comparison of Mean Gap Formation was
done using Kruskal Wallis test, then the difference was
found to be statistically significant between the two
Groups having the p value ˂0.05 (Table 1)
Post hoc pairwise comparison of Mean Gap formation
among two study groups was done using Mann Whitney U

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test and it was found that the Mean Gap formation among
Group A was significantly lower than that among Group B
samples. The results showed that the minimum Gap
Formation was found in Sonicfil composite, indicating
that the Incremental Fill composites have more
microscopic Gaps than Bulk Fill composites.
According to Sabbagh J et al12 Sonic Fill is a fast and
reliable new technique for posterior restorations which
does not require any additional capping layer. The
manufacturer stated that as Sonic energy is applied
through the handpiece, the modifier causes the viscosity
to drop (upto 87%), increasing the flowability of the
composite, enabling quick placement and precise
adaptation to the cavity walls,
Conclusion
The following conclusion was drawn:
 The Bulk Fill Composite (SonicFill) showed lesser
Gap Formation when compared to the Incremental Fill
Composite (Spectrum TPH).
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