Bulk filling versus layering technique: What has changed?

Bulk filling versus layering
technique: What has changed?
Prof. Joseph Sabbagh
Introduction
Despite the continuous use of dental amalgam in several countries, the use of resin
based composites have surpassed amalgam during the last 10 years. Every year
over 500 million direct restorations are placed worldwide, and of these, 261 million
are composites (Heintze and Rousson, 2012). When placed in optimal conditions, and
in low caries risk patients, composite restorations have demonstrated comparable or
even better performance (10-12 years) to that of dental amalgam (Opdam et al. 2010).
Prof. Joseph Sabbagh,
DDS, MSc, PhD, FICD
He graduated from Saint-Joseph
University in Beirut. In 2004, he
obtained his PhD in biomaterials from
the Catholic University of Louvain
(UCL), Belgium. In 2000 he obtained a
master in operative dentistry (restorative
dentistry and endodontics) from UCL.
Currently, he is an associate Professor
in the department of restorative and
aesthetic dentistry in the Lebanese
university and the director of several
research projects. He is also a fellow
researcher and a post-graduate lecturer
UCL (Cribio division), Belgium. His
private practice is limited to cosmetic
dentistry and endodontics. He is a
member of: the Academy of Operative
Dentistry USA, the editorial board of
Reality Endodontics Journal, USA,
the International Association of Dental
Research, and fellow of the International
College of Dentists.
Placement of posterior composites has a number of disavantages, polymerization
shrinkage, long placement procedure and obtaining an adequate contact point.
The layering technique is still considered as the standard technique for anterior and
posterior restorations. The thickness of each layer is limited to the maximum of 2 mm
for optimal polymerization and degree of conversion. Combined with the three steps
total etch bonding technique, the restoration of a posterior cavity can be considered
a time consuming procedure, extending to nearly twice the time taken to complete an
equivalent dental amalgam (Lynch et al. 2014).
The development and use of self-adhesive systems has allowed the dentist to shorten
the bonding procedure and at the same time reduce the postoperative sensitivity, due
to a partial removal of the smear layer from the cavity walls.
More recently bulk filling materials have been introduced to the dental market, and
today more than twelve systems are available. The main advantage of these materials
is their application in a 4 mm thick layer, resulting in a shorter placement time for
medium and deep posterior cavities. Other advantages reported are better adaptation
of the first layer of composite and absence of voids.
Bulk fill materials present in unidoses, syringes or tubes and can be classified according
to their consistencies and mode of applications into four groups. The first two groups
include the flowable and fiber based bulk filling materials, and the other two are the
high density and sonically activated bulk filling materials.
When using flowable or fiber-based bulk filling materials in class II cavities, care must
be taken not to place the materials on occlusal surfaces, or on cavity margins. The
final two millimeters occlusally are filled with a microhybrid composite, making the
restorative procedure longer and more complex.
Recent in-vitro studies have shown that flowable bulk filling materials suffer from low
mechanical properties mainly hardness and flexural modulus of elasticity (Czasch et
Ile, 2013, Leprince et al. 2014) and a high translucency. Their coverage by a thin layer
(1 to 2 mm) of a nanohybrid resin composite will ensure optimal occlusal functioning,
and mechanical resistance.
Compared to flowable bulk fill materials, high density bulk fill composites, such as
SonicFill™, have been shown to have high mechanical properties making them suitable
for use on the occlusal surface of a restoration.
The use of a bulk fill material to restore a class II cavity requires the placement of
a matrix, the application of an adhesive system (total or self etch system) and the
use of a high intensity light curing unit. If a liner is required, a recent literature review
recommend the use of bioactive dental materials only if the pulp is exposed or if the
remaining dentine thickness is less than 0.5 mm (Mouawad et al. 2014).
The SonicFill System is a sonically activated high density bulk fill material used for
posterior restorations. It is a closed system, consisting of a handpiece manufactured
by KaVo and a special composite unidose made by Kerr.
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A KaVo multiflex connector will allow the operator to connect
the handpiece to the dental unit. The use of the SonicFill System
combined with a self etch adhesive, represent a real gain of time
for the dentist when compared to the layering technique.
The SonicFill System is indicated for class I and class II posterior
restorations and as a build up material for cusp reconstruction,
as well as a base after root canal treatment. The long handpiece
allows easy access in the molar area.
The following clinical case illustrates teeth restoration using the
SonicFill System compared to layering technique.
Case report
A 32 year-old man presented for sensitivity in the posterior lower
left region. Upon clinical and radiographic examination, the first
and second left lower molars (#36 and 37) showed respectively
an occluso-distal caries and a secondary caries under the
existing composite restoration (Figure 1).
second molar (Figure 2) using a Softclamp and a Fixafloss (Kerr).
After rubber dam application, a medium size Metafix matrix
(Kerr) was placed around tooth (#36) and tightened manually
as indicated by the manufacturer. The two cavities (36 and
37) were restored simultaneously since only one contact point
reconstruction is involved. Tooth 36 was restored using the
SonicFill System, while tooth 37 was restored with a layering
technique with Herculite® XRV Ultra™ (Kerr) nanohybrid
composite.
A sixth generation two component self etch adhesive, OptiBond™
XTR, was used during the restorative procedure for both cavities.
The self etch primer is first applied using a microbrush and
rubbed for 20 seconds (Figure 3) then gently air dried (Figure 4).
Then the adhesive is brushed actively for 15 seconds to allow
bonding penetration in the dentinal tubules (Figure 5), air thinned
for 5 seconds and polymerized for 20 seconds using the new
LED Demi Ultra curing light (Figure 6).
After shade selection and local anesthesia, the cavities were
prepared under copious irrigation using a pear shape diamond
bur. A class II cavity (OD) was prepared on tooth 36 and a class I
on tooth 37. For optimal isolation and moisture control during the
restorative procedure, a preformed 3D-rubber dam OptiDam™
(Kerr) was applied and fixed from the first left premolar to the
Tooth 36 was bulk filled using an A3 compula of SonicFill
composite. The size and the shape of the unidose tip allowed
easy access to the cavity (Figure 7). The viscosity change of the
composite results in perfect adaptation to the cavity walls and
avoids any stickiness of the composite to the instrument.
1. Preoperative view
2. Metafix placement
3. Application of Optibond XTR etch and prime
4. Gentle air dry
5. Application of Optibond XTR bonding agent
6. Polymerization of the bonding
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Following placement of the composite into the cavity the
composite is adapted and shaped occlusally then polymerized
during 40 seconds from the occlusal side. Tooth 37 was filled
using three layers of Herculite XRV Ultra composite A3 Dentin,
A2 Enamel, and Incisal (Figures 8-10). The occlusal anatomy
was recreated, and almost no excess is observed. Each layer
of composite is polymerized for 20 seconds. After the Metafix
matrice removal, (figure 11) adequate occlusal anatomy is
observed in both cavities, with no overbuild or over contour.
Finishing the restorations is achieved using an egg shaped fine
diamond bur (Figure 12). This is followed by a silicone point and
an Occlubrush®, a silicone filled brush (Kerr) used to give a high
luster and polish to the restorations (Figures 13 and 14). Figure
15 is a postoperative view of the final restorations after finishing
and polishing.
Composite used in posterior cavities must fulfill the criteria of
high percentage of filler to withstand occlusal forces and a
low polymerization shrinkage. Materials must allow for good
adaptation to the cavity walls, thus reducing voids and allowing
the development of a tight contact point. According to the
7. SonicFill application
8-10. Composite application using the layering technique
11. Completed occlusal anatomy
12. Finishing with an egg shape fine diamond bur
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available literature, SonicFill demonstrates optimal mechanical
and physical properties that allows its use safely for posterior
restorations. Compared to the conventional layering technique,
the SonicFill bulk filling concept is a fast and reliable technique.
Unlike the layering technique, SonicFill is an easy technique to
learn allowing operators to achieve excellent results in a very
short time. It has an improved handling and delivers of a nonsticky, non-slumpy composite with optimal sculptability. The
material is easily visible on bitewing radiographs. In most cases
the restorative phase is reduced of at least 50 %.
References
Heintze S & Rousson V. Clinical effectiveness of direct class II restorations:
A meta-analysis. Journal of adhesive dentistry 2012;14 (5): 407-431. Opdam et
al., 12-years survival of resin composites vs amalgam restorations. Journal of
Dental Research 2010, 89: 1063-1067. Lynch CD, Opdam N, Hickel R, Brunton
P et al., Guidance on posterior resin composites: Academy of Operative Dentistry
- European Section. Journal of Dentistry, 2014; 42: 377-383. Czasch P & Ilie
N. In vitro comparison of mechanical properties and degree of cure of bulk fill
composites. Clinical and Oral Investigation 2013; 17(1):227-235. Leprince JG,
Palin W, Julie Vanacker J, Sabbagh J, Devaux J, Leloup G. Physico-mechanical
characteristics of commercially available bulk fill composites. Journal of Dentistry
2014, http://dx.doi.org/10.1016/j.jdent.2014.05.009 Mouawad S, Artine S, Hajjar
P, McConnell R, Fahd J, Sabbagh J. Frequently asked Questions in Direct Pulp
Capping: Dental Update 2014; 41(4): 298-304.
13. Polishing using a diamond point
14. Polishing with Occlubrush
15. Postoperative view
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