8/18/2019 Modified Fluid Wax Impression

1/4 Tan et al 

 This article describes a technique for making a definitive impression for highly displaceable residual ridges. The tech-nique is especially applicable for mandibular edentulous ridges. The choice of the impression materials, as well as thedesign of the impression tray, focuses on preventing distortion of the displaceable residual ridges during impressionmaking. Using an impression tray with an opening, modeling plastic impression compound and impression wax areused to accurately capture the shape of the residual ridge and place pressure onto denture load-bearing areas. Low-viscosity vinyl polysiloxane impression material is then used over the window opening to capture the surface details ofthe residual ridge without distorting the displaceable tissues. The use of this technique helps in maintaining the con-tour and capturing the detail of the tissues, as well as in accurately determining the extent of the muccobuccal dentureextensions. ( J Prosthet Dent 2009;101:279-282)

Modified fluid wax impression for aseverely resorbed edentulousmandibular ridge

Kian M. Tan, BDS,a  Michael T. Singer, DDS, MS,b Radi Masri,

BDS, MS, PhD,c and Carl F. Driscoll, DMDdBaltimore College of Dental Surgery, University of Maryland,Baltimore, Md

aPostgraduate Prosthodontics Resident.bClinical Assistant Professor; private practice, Bethesda, Md.cAssistant Professor.dProfessor, Program Director.

Making a definitive impression of

an edentulous arch can be challeng-

ing when the residual ridges present

with less-than-ideal conditions, es-

pecially when there is minimal bone

height, unfavorable residual ridge

morphology, and/or unfavorable

muscle attachments.1  Impressions

are also challenging when the mucosa

overlying the residual alveolar ridges is

highly displaceable. Displaceable, hy-

perplastic, or flabby tissues are com-

monly seen in the anterior region of

the maxilla in combination syndrome2 

or in the mandibular alveolar ridge

when extensive bone resorption has

occurred.3  Displacing such residual

ridge tissues during impression mak-

ing is always a concern. Soft tissues

that are displaced during impressionmaking tend to return to their original

form, and complete dentures fabri-

cated from the impression will not fit

accurately on the recovered tissues. As

a result, loss of retention and stability

of the dentures, discomfort, and gross

occlusal disharmony may occur.4

Most impression techniques for

the management of displaceable tis-

sues have been described for the an-

terior maxilla,5,6  and techniques to

manage displaceable tissues in the

mandible during impression making

are rarely reported. Due to the ana-

tomical differences between the max-

illa and the mandible, as well as the

differences in primary and secondary

load-bearing areas, impressions of

mandibular ridges with displaceable

tissues require special considerations.

A classic impression technique

commonly used for the fabrication

of immediate complete dentures7  or

the treatment of patients with com-

bination syndrome5  uses a custom

impression tray with a window open-

ing in the anterior region. When themaxillary edentulous ridge presents

with anterior hyperplastic tissues,

a zinc oxide eugenol impression is

first made, and a creamy mix of im-

pression plaster is then painted onto

the displaceable tissues.5  Impression

plaster produces little pressure, but

it is difficult to handle and difficult

to pour 8  and offers little advantage

over contemporary low-viscosity vinyl

polysiloxane materials.

Mandibular residual ridges with

adequate bone support can usually

be precisely recorded with elastomer-

ic impression materials because of

the inherent accuracy of these materi-

als and their propensity to distribute

pressure equally. As the residual ridg-

es resorb, the tissues become unsup-

ported and displaceable; the use of an

elastomeric impression material in a

confined tray will result in a distorted

impression. Therefore, the impression

technique should be modified to pre-

vent distortion of unsupported and

displaceable tissues. A functional im-

pression technique, such as fluid wax,captures the primary and secondary

load-bearing areas without distortion

of the residual ridge. In the mandible,

the alveolar residual ridge serves as a

secondary load-bearing area, with the

buccal shelves serving as the primary

load-bearing area.9,10

8/18/2019 Modified Fluid Wax Impression

2/4

80  Volume 101 Issue 4

 The Journal of Prosthetic Dentistry   Tan et al 

According to Applegate,11 the use

of fluid wax in impression making was

described previously by Everett. It has

the following advantages: (1) it can

be easily controlled to gain maximum

coverage; (2) it can be corrected read-

ily; (3) it can be used to accurately de-

termine the extent of the muccobuc-

cal reflections; and (4) it can be usedto direct pressure to the load-bearing

areas, specifically, the buccal shelves

and the slopes of residual ridges in the

mandible.10,11  The low-viscosity elas-

tomeric impression material is advan-

tageous because it creates minimal

pressure, produces accurate details,

does not distort easily, and is easy to

handle.12,13 

An alternative method of making

a definitive impression for mandibularedentulous arches with displaceable

tissues, using impression wax and vi-

nyl polysiloxane impression material,

is described.

 TECHNIQUE

1. Make a preliminary impression

of the edentulous arch (Fig. 1) using

irreversible hydrocolloid impression

material (Jeltrate Alginate; Dentsply

Caulk, Milford, Del) in a metal stock

tray (Rim-Lock Impression Tray;

Dentsply Caulk).

2. Pour the impression in type III

dental stone (Modern Materials Den-

stone; Heraeus Kulzer, Armonk, NY)

(Fig. 2).

3. Fabricate a custom impression

tray on the preliminary cast using

light-polymerized acrylic resin tray

material (Triad TruTray; Dentsply Tru-

byte, York, Pa). Adjust the border ex-tension of the tray to be at least 2 mm

short of the vestibules on the prelimi-

nary cast.9

4. Evaluate and adjust the exten-

sion of the tray in the mouth, if nec-

essary. Soften modeling plastic im-

pression compound (Gray Stick; Kerr

Corp, Orange, Calif) in a water bath

at 53°C, and place it on the intaglio

surface of the tray, corresponding to

the region of the mandibular centralincisors and both the mandibular first

molars, to serve as spacers for impres-

sion wax.

5. Border mold the tray with mod-

eling plastic impression compound in

segments.

6. Remove the spacers with a scal-

pel blade (Becton, Dickinson and Co,

Franklin Lakes, NJ) once the border

molding is completed.7. Trim the tray over the crest of

the residual ridge, and create a win-

dow opening above the displaceable

alveolar ridge using a No. 8 round

bur (Brasseler USA, Savannah, Ga),

similar to the tray design described

by Watson.5 Determine the size of the

window opening according to the ex-

tent of the displaceable tissues (Fig.

3).8. Melt the mouth temperature im-

 1  Mandibular edentulous ridge with severe bone resorption.

 2  Preliminary cast. Note distortion of left alveolar ridge lingually dueto pressure exerted by irreversible hydrocolloid impression material.

3  Window opening of impression tray.

8/18/2019 Modified Fluid Wax Impression

3/4

281April 2009

 Tan et al 

pression wax (D-R Miner Dental Wax-

es, Medford, Ore) in a container held

in a water bath at 42°C, and apply

the impression wax onto the borders

of the tray with a wax spatula while it

is still fluid. Ensure that the tempera-

ture used to melt the impression wax

is less than the working temperature

of the modeling plastic impression

compound used in the border mold-

ing procedure, to prevent distortion.

9. Place the impression tray imme-diately over the edentulous ridge, and

leave it in the mouth for approximate-

ly 5 minutes. Allow adequate time for

the mouth temperature impression

wax to flow and escape to the periph-

ery of the impression, as well as to

solidify.

10. Remove the impression tray

from the mouth and cool it immedi-

ately in water at room temperature.

11. Add impression wax in incre-ments on the periphery until a defi-

nite reproduction of the muccobuccal

fold is obtained.

12. Apply impression wax onto the

intaglio surface of the tray to capture

the remaining surfaces of the residual

ridge. Add impression wax onto the

slopes of the ridge, rather than the

crest, in increments,10  until a glossy

surface is visible.11  Maintain the in-

tegrity of the residual ridge by exerting

pressure onto the slopes (Fig. 4).

13. Trim away any excess impres-sion wax on the periphery or over

the window opening with a scalpel

blade.

14. Apply adhesive (Caulk Tray

Adhesive; Dentsply Caulk) on the tray

in the area surrounding the window

opening, and allow it to dry.

15. Place the impression tray

onto the residual ridge and inject vi-

nyl polysiloxane impression material

(Aquasil Ultra Monophase RegularSet Smart Wetting Impression Mate-

rial; Dentsply Caulk) over the window

opening. Prevent distortion of the

soft tissues by placing the impression

material in the most passive manner

possible.

16. Gently blow air onto the im-

pression material to allow the spread

of the impression material over the

mucosal surfaces.

17. Allow the impression material

to polymerize according to the manu-

facturer’s recommendation (Figs. 5and 6).

18. Remove, disinfect, and box the

impression using a mix of plaster and

pumice as described by Martin et al

(Fig. 7).14 Avoid using a conventional

boxing procedure that requires box-

ing wax, as it may distort the impres-

sion wax.

19. Pour the impression in type

III dental stone (Modern Materials

Denstone; Heraeus Kulzer) as soon aspossible (Fig. 8).

 4  Fluid wax impression.  5  Application of vinyl polysiloxane impression materialover window opening.

 6  Completed modified fluid wax impression.  7  Boxing of impression.

8/18/2019 Modified Fluid Wax Impression

4/4

82  Volume 101 Issue 4

 The Journal of Prosthetic Dentistry   Tan et al 

SUMMARY 

A definitive impression technique

using both impression wax and vi-nyl polysiloxane impression material

for displaceable mandibular residual

ridges is described. Consideration has

been given to the choice of impres-

sion materials as well as to the design

of the impression tray to minimize the

amount of pressure exerted onto the

displaceable regions of the residual

ridges during the impression-making

procedure.

REFERENCES

1. McGarry TJ, Nimmo A, Skiba JF, AhlstromRH, Smith CR, Koumjian JH. Classifica-

tion system for complete edentulism. TheAmerican College of Prosthodontics. JProsthodont 1999;8:27-39.

2. Kelly E. Changes caused by a mandibularremovable partial denture opposing amaxillary complete denture. J Prosthet Dent1972;27:140-50.

3. Xie Q, Närhi TO, Nevalainen JM, Wolf J, Ainamo A. Oral status and prostheticfactors related to residual ridge resorptionin elderly subjects. Acta Odontol Scand1997;55:306-13.

4. Lytle RB. The management of abused oraltissues in complete denture construction. JProsthet Dent 1957;7:27-42.

5. Watson RM. Impression techniquefor maxillary fibrous ridge. Br Dent J1970;128:552.

6. Lynch CD, Allen PF. Management of theflabby ridge: using contemporary materi-als to solve an old problem. Br Dent J2006;200:258-61.

7. Campagna SJ. An impression techniquefor immediate dentures. J Prosthet Dent1968;20:196-203.

8. Freeman SP. Impressions for complete den-

tures. J Am Dent Assoc 1969;79:1173-8.9. Zarb GA, Bolender CL, Eckert SE, Fenton

AH, Jacob RF, Mericske-Stein R. Prost-hodontic treatment for edentulouspatients: complete dentures and implant-supported prostheses. 12 ed. St. Louis:Mosby; 2003. p. 232-33, 246.

10.Boucher CO. A critical analysis of mid-century impression techniques for fulldentures. J Prosthet Dent 1951;1:472-91.

11.Applegate OC. Essentials of removable par-tial denture prosthesis. 3rd ed. Philadephia:

 WB Saunders; 1965. p. 254-5.12.Al-Ahmad A, Masri R, Driscoll CF, von

Fraunhofer J, Romberg E. Pressure gener-

ated on a simulated mandibular oralanalog by impression materials in customtrays of different design. J Prosthodont2006;15:95-101.

13.Masri R, Driscoll CF, Burkhardt J, VonFraunhofer A, Romberg E. Pressure gener-ated on a simulated oral analog by impres-sion materials in custom trays of differentdesigns. J Prosthodont 2002;11:155-60.

14.Martin JW, Jacob RF, King GE. Boxing thealtered cast impression for the dentateobturator by using plaster and pumice. JProsthet Dent 1988;59:382-4.

Corresponding author:Dr Radi Masri650 West Baltimore St, Room 4228Baltimore, MD 21201Fax: 410-706-1565E-mail: rmasri@umaryland.edu

Copyright © 2009 by the Editorial Council forThe Journal of Prosthetic Dentistry.

 8  Resultant definitive cast.

Availability of Journal Back Issues

As a service to our subscribers, copies of back issues of The Journal of Prosthetic Dentistry  for the preceding 5 years aremaintained and are available for purchase from Elsevier Inc until inventory is depleted. Please write to Elsevier Inc,Subscription Customer Service, 6277 Sea Harbor Dr, Orlando, FL 32887, or call 800-654-2452 or 407-345-4000 forinformation on availability of particular issues and prices.