Expedited polychromatic Class IV restoration
by Dr. Arthur R. Volker
When designing or improving
an entire smile, be it directly
or indirectly, the clinician or
technician is a creator, tasked
with producing an artistic masterpiece.
However, in the case of an
incisal fracture, the clinician is less a
creator and more a master forger, needing
to mimic all optical aspects of the
surrounding and adjacent dentition.
This can be challenging in terms of
shade selection, because the most color
variability is typically found at the
incisal third of the incisor. This holds
especially true of younger patients,
who often have prominent translucencies
and opacities in this region.
Several tactics can help manage
the layering of the composite masses
in these scenarios. The use of a palatal stent is a predictable way to
do this.1–4 In this technique, a wax-up
or mock-up of the fractured area is
fabricated on a model and a putty PVS
stent or index is fabricated. From that,
a thin layer of a strong, semitranslucent
composite—typically a nano- or
microhybrid—is placed on the stent,
replicating the palatal surface. Subsequent
layers of composite of varying
opacity and translucency are then
layered to the facial, creating a seamless
restoration (Figs. 1a–1c). Because
it is created from a wax-up, occlusal
factors should be well controlled.
Figs. 1a-1c: Palatal stent used to guide layering of Class IV restoration.
A disadvantage with this technique
is that a mock-up is needed, either
intraorally or with a wax-up on a
model. This can be time-consuming
and may require a second appointment,
which may be difficult or
impractical, especially with a pediatric
or emergency patient. Additionally,
in cases of small fractures,
placement of composite masses may
be more difficult to manage than
with larger fractures.
An alternative approach, the “blank
canvas technique,” can provide an
expedited polychromatic restoration
for small fractures, emergency cases
or pediatric patients. It uses a chromatic
microhybrid base, followed by
tints or opaquers if needed, and covered
by a thin layer of an achromatic
microfilled composite. The objective
is to mask the fracture and provide a
lifelike restoration that matches the
translucencies and opacities of the
surrounding dentition.
Materials
Chromatic microhybrid canvas
A chromatic microhybrid is used as
the base or canvas of the restoration.
Approximately 80–85% of the restoration
will be composed of microhybrid
composite.
The advantage of the chromatic
microhybrid is twofold. First, its
high flexural strength will help resist
against occlusal loading.5,6 Secondly,
the high opacity of the microhybrid
will help mask any fractures.7,8
The issue with microhybrids is that
they do not hold a polish well, and may
look dull over time.
Tints and opaquers
In lieu of using composite bodies to
replicate the varying translucencies
and opacities, flowable opaquers and
tints will be used for this function.
The polychromatic appearance of
the incisal edge is a function of light
being either reflected or transmitted
through the buccal and lingual surfaces
of the enamel. This is an optical
effect and not an anatomic feature;
the translucent or opalescent phenomena
is observed when light is reflected
within the crystalline structure of the
enamel. When light is transmitted in
this same area, an opacity can be seen
at the incisal edge.9 This is referred to
as a counteropalescent effect or, more
commonly, an “incisal halo.”10
A strong opalescence will typically
have a strong counteropalescence.
To illustrate, Fig. 2 demonstrates an
incisal halo that can be observed on
the incisal edge of the fracture on
tooth #9. A more traditional opalescence/
counteropalescence pattern can
be seen on #8.
The appearance of translucency can
be replicated with gray, violet or blue
tints. To enhance the incisal halo, a
white or shade opaquer can be used.
Note that flowable opaquers can also
be used to reproduce calcifications
or maverick effects and help mask
fracture lines.11
Microfilled composite
The final and most facial portion of
the restoration will be a microfilled
composite, which is easy to polish and
maintain its polish over time.12 Fig. 3
shows a nine-year follow of a layered
composite veneer on Tooth #9. The patient had not seen a dentist since
the veneer was completed. Exposed
to the same oral conditions, the dull
appearance of the microhybrid on the
distoincisal portion can be contrasted
with the high luster noted on the
microfilled composite.
Fig. 2: Incisal halo noted on fractured portion of #9.
Typical clinical presentation of incisal halo noted
on #8 restoration.
Fig .3: Difference between the high-luster microfill,
left, versus a microhybrid, after nine years.
Microfilled composites are radiolucent,
especially when compared with
microhybrids,13 which may present a
diagnostic issue on radiographs, especially
in interproximal areas. Because
they are inherently weak, microfills
should not be placed on any areas that
will be under occlusal loading.6 Only
a small amount will be used, keeping
the occlusal loading on the much
stronger microhybrid composite.
Case example with tints
A patient was unhappy with a
two-week-old restoration on the incisofacial surface of tooth #8
because she thought the central
incisors did not match. Upon inspection,
it was noted that although the
single-shade composite did match the
base shade of the tooth, additional
color (hue) was needed to mimic the
adjacent tooth (Fig. 4).
The teeth were isolated with a
heavy latex-free rubber dam (Isodam,
4D Rubber). The existing composite
was removed; a chromatic microfilled
composite was placed and a white
tint (Creating Color, Cosmedent) was
applied with a #8 K-file in a horizontal
motion to replicate the horizontal
pattern (Fig. 5). An achromatic microfilled
composite was then added. Fig. 6
demonstrates the immediate postop
result, and Fig. 7 reveals the four-year
follow-up, demonstrating the retained
polish of the microfilled composite.
Fig. 4: Initial presentation of unaesthetic
single-shade restoration.
Fig. 5: #8 K-file used to create
horizontal hyperchromatic effects.
Fig. 6: Immediate postop photo.
Fig. 7: Four-year recall of restoration.
Blank canvas demonstration
PREPARATION
Masking the fracture involves a two-step
approach.
The first preparation is a chamfer,
1–1.5 mm long and 0.5 mm deep, along
the periphery of the fracture, typically
made using a round diamond bur. This
preparation is to help mask evidence
of the fracture. The chamfer will be
covered with a microhybrid.
The second preparation will be a
long bevel—often referred to as an
infinity bevel or a starburst bevel14—which will help allow the microfilled
composite to blend into the body of
the tooth. The long bevel is prepared
with a flame diamond and placed in
an irregular pattern.
Fig. 8 demonstrates the initial
situation with an MILF fracture on
Tooth #9. Rough and sharp areas were smoothed, and a round diamond bur
was used to create the shallow chamfer
for the transition zone (Fig. 9).
A flame diamond was used to create
the infinity bevel (Fig. 10).
Fig. 8: Initial preop photo demonstrating
Class IV fracture.
Fig. 9: Round diamond bur used to create
chamfer of transition zone.
Fig. 10: Flame diamond
used to create infinity bevel.
COMPOSITE LAYERING
A chromatic microhybrid (Renamel
Microhybrid, Cosmedent)—Shade A1
in this example—was used to recreate
most of the restoration. The
microhybrid will compose the entirety
of the palatal aspect, and must cover
the entirety of the chamfer of the transition
zone on the facial aspect. It is
not advisable to have the microhybrid
go past the chamfer margin, because it
may leave no room for the microfilled composite and that aspect of the
restoration may look dull over time,
creating an optical disharmony.
Note that if the chamfer is not
covered completely, a fracture may
still be visible. If needed, a flowable
opaquer could be added to further
mask the fracture line. This creates
the “blank canvas.” Excess or occlusion
can be adjusted at this point.
This is done dry, then an unfilled resin
(Complete Unfilled Resin, Cosmedent)
is added onto the restoration. Fig. 11
demonstrates the placed and adjusted
microhybrid.
Because the adjacent central incisor
had a large amount of incisal translucency,
as well as a prominent incisal halo, a thin, sharp probe (Matt’s
Probe) was used to place gray tint
(Creative Color, Cosmedent) on the
incisal third, taking care to avoid the
incisal edge (Fig. 12).
Fig. 11: Chromatic microhybrid placed
over chamfer of transition zone,
creating a “blank canvas.”
Fig. 12: Flowable gray tint placed to simulate
translucency.
The inherent opacity of the microhybrid
could often serve as the incisal
halo at the edge of the tooth, though
if desired, the incisal halo can be
further enhanced using a flowable
opaquer. In this case, a 50/50 combination
of white and A1 opaquer,
mixed in a resin keeper, was applied
to the incisal edge using the probe
(Fig. 13). Fig. 14 shows the effect of
cured tints and opaquers over the
microhybrid composite, revealing a
polychromatic effect.
Fig. 13: Flowable opaquer used on incisal
edge to replicate the incisal halo.
Fig. 14: Tints and opaquer cured. Note
creation of polychromatic appearance.
To enhance the incisal effects of
the tints and opaquers and provide
a lasting polish, a small amount of
achromatic microfilled composite
(Light Incisal, Cosmedent) was placed
as a final layer. The composite should
cover the infinity bevel created by the
flame diamond and should be only on
the facial aspect of the restoration, not
placed on any occluding areas. Fig. 15
illustrates the placed, shaped
microfilled composite. (A chromatic
composite could also be used if incisal
effects are not pronounced.) Using a
combination of discs and polishers,
the restoration was finished to mimic
the adjacent tooth (Fig. 16).
Fig. 15: Achromatic microfill used
to overlay facial aspect.
Fig. 16: Final outcome.
Figs. 17–21 illustrate some other
clinical examples of teeth restored
with the technique.
Fig. 17
Fig. 18
Fig. 19
Fig. 20
Fig. 21
Conclusion
The blank canvas technique presents
an expedited method to resolve
polychromatic Class IV fractures in
cases such as trauma (both adult
and pediatric) as well as for small
fractures, where it may be difficult to
manipulate composite masses or if a
palatal stent might be untenable.
Table 1 lists advantages and disadvantages
of the technique.
TABLE 1
Note that nanofilled or nanohybrid
composites can also be used
for this technique if a smaller inventory
is desired, though there may
be a slight aesthetic and functional
compromise.
References
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Dr. Arthur R. Volker graduated from the Columbia University School of
Dental and Oral Surgery. He is a member of the continuing education
committee for the New York State Academy of General Dentistry. Volker
is a diplomate of the World Congress of Minimally Invasive Dentistry,
and is a fellow of the Academy of General Dentistry and the American
College of Dentists. He has also published articles and lectures on
such topics as cosmetic dentistry, minimally invasive dentistry, dental
materials and dental implants. He practices in Sunnyside, New York.