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: uludag@dentistry.ankara.edu.trDOI: 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

REFERENCES

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2. Uludag B, Celik G, Ozturk O. Alternate functionalimpression technique for implantretained overden-tures. J Prosthet Dent. 2007;97:242–243.

3. Uludag B, Celik G. An alternative impressiontechnique for implant-retained overdentures. J ProsthetDent. 2006;96:377–378.

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.

5. Ganddini MR, Schejtman N, Ercoli C, Graser GN.Prosthodontic application for implant carriers. J ProsthetDent. 2004;92:399–402.

6. Mericske-Stern RD, Taylor TD, Belser U. Manage-ment of the edentulous patient. Clin Oral Implants Res.2000;11(suppl 1):108–125.

7. Uludag B, Sahin V. A functional impressiontechnique for an implant-supported overdenture: aclinical report. J Oral Implantol. 2006;32:41–43.

Uludag

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