An Alternate Pressure-Free FunctionalImpression Technique forImplant-Retained OverdenturesBulent Uludag, DDS, PhD*
Overdenture treatment provides an esthetic and functional result that allows proper access
for hygiene and maintenance. For implant-retained overdentures to be successful, functional
loads must be distributed optimally to the mucosa and the abutments. For this purpose,
impressions must record the soft tissue supporting areas simultaneously with accurate
registration of the implant components. Usually, finger pressure is used to make functional
impressions. This article describes an alternate pressure-free functional impression technique
for implant-retained overdentures.
Key Words: implant-retained overdenture, impression technique
INTRODUCTION
An overdenture impression must
record the soft tissue support-
ing areas simultaneously with
accurate positioning of the
implant components.1 Func-
tional impression technique records the
alveolar mucosa in a functional state and
simultaneously records the implant compo-
nents in relation to the alveolar tissues.2
Three types of impression techniques
have been described in the literature.3 A
single-stage impression procedure is com-
monly used with an open or closed tray
technique.4,5 A double-impression tech-
nique for overdentures retained by only
2 implants has been suggested, using a
zinc oxide eugenol (ZOE) impression paste
and polyether impression material.6 The third
type of impression technique is a functional
impression technique for implant-retained
overdentures.3,7 All of these techniques require
operator finger pressure. It is possible to make
a functional impression without finger pressure
for implant-retained overdentures by using cap
attachments. Also, an implant-retained over-
denture has characteristics resembling those of
a complete denture with a combination of
tissue support and implant retention.6 Thus,
the resilience difference between implant and
mucosa should be considered for the impres-
sion of implant tissue–retained overdentures.3
Therefore, the impression technique must
provide an accurate resilience difference be-
tween implant and mucosa.
This article describes an alternative func-
tional impression technique that can be used to
fabricate implant-retained mandibular over-
denture reinforcement with metal framework.
The step-by-step procedure for this
alternative functional impression technique
is as follows:
* Corresponding author, e-mail: [email protected]: 10.1563/AAID-JOI-D-09-00036
Department of Prosthodontics, Ankara University,Besevler, Turkey.
CLINICAL
Journal of Oral Implantology 205
1. Replace healing caps(Zimmer Dental Inc,San
Diego, Calif) on the osseointegrated dental
implants with ball abutments (Zimmer Den-
tal). Place ball abutment transfers (Zimmer
Dental) on the ball abutments (Figure 1a).
2. Obtain a preliminary impression of the
mandibular arch with irreversible hydro-
colloid (CA 37, Cavex Holland BV, Haar-
lem, The Netherlands) with a stock tray.
3. Pour the mandibular cast with dental
stone (Moldano, HeraeusKulzer GmbH,
Hanau, Germany).
4. Place cap attachments (Zimmer Dental)
parallel on ball abutments with paraskop
(Bego, Bego Dental, Bremen, Germany).
5. Take the cast metal framework (Wiro-
nium, Bego Dental) and combine cap
attachments with a self-curing acrylic
resin (Meliodent, Heraeus Kulzer).
6. Place 1-mm-thick dental wax (Heraeus
Kulzer) on the mandibular model.
7. Fabricate an acrylic custom tray (Heraeus
Kulzer) (Figure 1b) and place the custom
tray on the ball abutments in the mouth;
check the relationship of soft tissues.
8. Border mold this impression tray with
plastic impression compound (Impres-
sion Compound, Kerr Italia SpA, Salerno,
Italy).
9. Take the impression of the alveolar mucosa
with a ZOE impression paste (Cavex Outline,
Cavex Holland BV, Haarlem, The Nether-
lands) (Figure 2a) without finger pressure.
10. Place ball abutment analogues (Zimmer
Dental) into cap attachments (Figure 2b).
11. Pour the impression with Type IV stone
(Begostone, Bego Dental).
DISCUSSION
The described method is technique sensitive
and requires parallel placement of cap
FIGURE 1. (a) Intraoral view of ball abutment transfer components in the mandible. (b) Intaglio surface ofacrylic custom tray.
FIGURE 2. (a) Impression of edentulous areas with zinc oxide eugenol paste. (b) Definitive impression ofthe mandible.
An Alternate Impression Technique
206 Vol. XXXVI/No. Three/2010
attachments. Otherwise, the probability of
obtaining an erroneus impression increases. A
pressure-free impression is obtained by means
of retention provided through cap attach-
ments. However, this impression method is
technique sensitive for providing a perfect
border relationship with various impression
materials. Additionally, it is more time con-
suming compared with single-stage impres-
sion procedures for overdentures.
CONCLUSION
The main advantage of this technique is it
provides an accurate relationship of implant
components to supporting tissues without
finger pressure. Delivery of the prosthesis
constructed with this impression technique
results in a decrease in postinsertion appli-
ance adjustments.
ABBREVIATION
ZOE: zinc oxide eugenol
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4. De La Cruz JE, Funkenbusch PD, Ercoli C, MossME, Graser GN, Tallents RH. Verification jig for implant-supported prostheses: a comparison of standardimpressions with verification jigs made of differentmaterials. J Prosthet Dent. 2002;88:329–336.
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Uludag
Journal of Oral Implantology 207