If you peruse the Dentaltown implant discussion boards, the
subject of implant impression techniques is a frequent area of
frustration and discussion. We strive for stability and accuracy in
our implant impression techniques and as we do so, we must balance
the accuracy of the techniques with their ease and efficiency.
The debate on the accuracy of open versus closed impression
tray technique continues to drag on, with opinions and research
split nearly equally between each technique. Almost universally
agreed upon is the need for an accurate and more rigid impression
material. In the past, the gold standard in this area was
thought to be polyether – loved for its rigidity and accuracy, but
hated for its setting time, taste and smell.
All current impression material systems include light,
medium and heavy body materials, depending on practitioners'
preferences and clinical material demands. The heavy body
materials in this category tend to have a Shore A hardness in the
range of 50-60. The following is a presentation of implant
impressioning techniques using a newer vinyl polyether silicone
(EXA'lence, GC America).
New Rigid Impression Material
This newer impression system reaches outside of this standard
and brings to clinicians a heavy body rigid material that is
key to the techniques that will be presented. The heavy body
rigid material, with its Shore A hardness of 82 brings a rigidity
and stability that was previously only available in putty and bite
registration material. Traditional polyether materials have a
Shore A of 60. Given its rigidity, this newer viscosity/rigidity
material was intended to be used exclusively for triple tray quadrant
applications (Fig. 1). These properties allowed for predictable
and excellent clinical results, even in second molar and
The rigidity of the material however, precluded its use in
full-arch applications. This paradoxically made it the perfect
material for implant impressions without the ability to use it in
such an application. By modifying its intended use and utilizing
a mixture of viscosities, clinicians can enjoy the rigid stability of
the heavy body rigid material in a full-arch implant technique.
After the impression tray size has been selected and tried in
on the patient, the area of the tray that will receive the implant
impression coping is marked with indelible marker. This area is
then filled with the heavy body rigid material (Fig. 2). This sectional
filling of the impression tray will allow for the benefits of
the ultra-rigid material, without the risk of locking the tray in
the patient's mouth due to increased rigidity.
The remainder of the tray is then filled with heavy body impression
material (Fig. 3). Finally, a bead of extra light wash is extruded
throughout the arch as well as in the area of the impression coping
(Fig. 4). This will facilitate capture of occlusal morphology detail
but also intimate capture of the impression coping surface and
retention areas. In the cross section, the impression material strata
can be visualized (Fig. 5). The components are organized to maximize
their material benefits in the implant impression procedure.
In the final implant impression, all of the components of an
excellent implant transfer impression can be seen. Fine, detailed
capture of the transfer coping can be visualized on the internal
aspect of the impression (Fig. 6). With the impression coping
and analog seated, the light body's subgingival extension can be
seen to accurately record the existing emergence profile that has
been formed by the implant healing cap (Fig. 7).
The final clinical results (Fig. 8), with no required adjustments
in this case, are a reflection of not only the accuracy, but
the efficiency of this new implant impressioning protocol. This
protocol, using user-friendly crown and bridge impression materials
with unique viscosities and applications, is a welcome addition
to our impressioning armamentarium.
Acknowledgement: The author acknowledges receiving an honoraria and
material support from GC America for writing this article.