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Fig. 1: Preoperative image of the crown
to be removed with recurrent decay
Fig. 2: Preoperative image of crown prior
to removal
Fig. 3: Image of the preparation. What
remained was stained hard dentin
Fig. 4: Screen shot of the preparation as
imaged using the CEREC camera
Fig. 5: Screen shot of the pre-existing
tooth being copied in the software
Fig. 6: The CEREC software produced a
proposal of the restoration prior tomilling
IPS e.max CAD restoration using the
Speed Crystallization process.
Case study
A patient presented with a pre-existing
crown restoration affected by recurrent
decay (Fig. 1). After closer evaluation and
excavation, an in-office CAD-fabricated
crown was decided upon.
Because the crown anatomy was good,
occlusion was perfect and the patient
was comfortable with the buccal/lingual
width, the Biogeneric copy function was
usedtoduplicateandrecreatetheanatomy
and morphology of the existing resto-
ration (Fig. 2). To accomplish this task,
preoperative impression scans were taken
prior to removing the existing restoration
and preparing the tooth. This involved
applying an opaquing spray (CEREC
Opti-Spray, Sirona) to the existing resto-
ration. Then, impression scanswere taken
using CEREC for designing the chairside
restoration (IPS e.max CAD).
The spray was cleaned from the tooth,
after which the crown was removed. The
crown preparation was refined using
a series of diamonds for a smoother
preparation. Old build-up material was
removed, and caries detect was placed
to determine if any residual decay
remained. What remained was stained
hard dentin (Fig. 3). The ideal shade
(A3) was chosen for the lithium disilicate
block. Opaquing spray was again applied,
and scans were taken of the preparation
using the CEREC camera (Fig. 4).
The images obtained of the existing
crown prior to its removal were used to
duplicate cusp tips, fissure depths and
overallmorphology.Theywerethenapplied
to the preparation scans inorder to render a
new restoration that matched the original
(Fig. 5). Essentially, the pre-existing tooth
was copied in the CEREC software. The
white linewas redrawn, andanything inside
of itwas copied at 1:1with the original.
The CEREC software produced a
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