Nantawan Kolakarnprasert, DDS
Camila S. Sampaio, DDS, PhD, MS
Ronaldo Hirata, DDS, PhD, MS
A LARGE CAVITY IN A POSTERIOR TOOTH can be either incrementally restored or bulk filled
with resin composite. In the past, the incremental placement of a composite layer was the
standard technique in order to prevent polymerization shrinkage and shrinkage stress. 1 However,
one disadvantage of this technique was that air could become trapped between each layer. Also,
it was more time-consuming due to the number of steps and layers that had to be applied. 2
Due to the disadvantages of the incremental technique, the bulk-fill
technique for direct posterior restorations was introduced. This technique
is less sensitive and less time-consuming, and it has been widely accepted
in dental practices. 3 Bulk-fill technology allows up to 4 or 5 mm of composite (depending on the manufacturer) to be placed in a single layer. Bulk
fill composites such as Tetric EvoFlow Bulk Fill (Ivoclar Vivadent) claim
to reduce polymerization stress due to the incorporation of stress relievers,
which can result in better marginal adaptation and enhanced bond durability. Also, the bulk-filling technique has been reported to decrease
cuspal deflection significantly, compared to traditional incremental filling,
after adequate light polymerization of resin composites. 4, 5
Today, most flowable bulk-fill composites have higher translucency,
compared to conventional flowable composites, in order to allow deeper
penetration of light energy and higher depth of cure, thereby increasing
polymerization of the restoration. But this beneficial property can also
lead to a compromised esthetic restoration. After the preparation has been
completed, the remaining pulpal floor usually reveals color irregularities.
Under the threat of bacterial invasion, the pulp may attempt to protect
itself by forming reparative dentin, resulting in an arrested carious lesion. 6
The arrested carious lesion is hard, and its surface is a yellow to dark brown
color. 7 A second type of color irregularity can be found after amalgam removal; metal color can remain “tattooed” along the prepared tooth structure.
These color irregularities can appear through the more translucent restorative materials and compromise the final esthetic result.
The following case study shows how these types of color irregularities can be managed efficiently while still taking advantage of bulk-fill
A 26-year-old patient visited a private office
for a regular dental checkup. The clinical evaluation showed a No. 18 Class I composite
restoration with marginal leakage and infiltration on the distal side of the cavity ( figure
1). The surface of the restoration was irregular
and lacked dental anatomy. Due to the patient’s esthetic needs and the remaining
amount of natural tooth structure, composite
filling was selected for the restoration.
Figure 1: An old composite restoration with
microleakage on the distal side of the cavity.
The surface anatomy of the restoration was
The existing composite restoration was
removed with a No. 1015 diamond bur (KG
Sorensen) mounted on a high-speed handpiece.
Then, decayed tooth structure was removed
using low-speed metal burs and a hand excavator. After the cavity was completely clean, a
rubber dam was placed with a traditional 26
clamp on tooth No. 18.
The selective etching technique was chosen,
and 37% phosphoric acid (Total Etch, Ivoclar
Vivadent) was applied for 30 seconds. The tooth
was irrigated with water spray and air-dried
( figure 2). Next, a universal bonding agent (
Adhese Universal, Ivoclar Vivadent) was scrubbed
on the cavity surface until an immobile layer
was achieved ( figure 3). The excess solvent was
removed with an air stream for 20 seconds, and
the adhesive was light cured for 10 seconds with
an LED light (Bluephase Style, Ivoclar Vivadent)
1 mm away from the cavity.
SCIENCE & TECH