Preliminary silicone putty casts: Diaguosis to final impression for complete dentures

Keith E. Kinderknecht, DMD,a John T. Dominici, DDS,a and Evelyn Patella-Clark, DMDa University of Keu.tucky College of Dentistry, Chandler Medical Center, Lexington, Ky.

Silicone putty casts are useful for articulating existing dentures for evaluation and problem solving before relining procedures are performed or a new prosthesis is made. Tissue health may require significant modification of the existing dentures and treatment with tissue-conditioning material before final impressions are made. This practical procedure uses a functional impression that substitutes for a quality preliminary impression and combines tissue condition~g, a functional impression, silicone putty cast, custom fina.l impression tray, and a final impression for a complete denture. (J PROSWET DENT 1996;‘75:453-6.)

T he use of silicone putty casts enables the dentist to make and articulate completely edentulous diagnostic casts and existing dentures in one appoi.ntment.l The ex- cellent quality of these casts provides a visual aid for eval-

uation of interarch relationships, surgical intervention, occlusion, and the condition of the existing complete den- tures. To duplicate the edentulous arch in silicone putty, the mixed putty must be carefully adapted to the intaglio surface of the denture without trapping air and creating voids. This procedure can facilitate diagnosis and problem solving related to relining or remaking complete dentures, overdentures, and implant-supported complete dentures.

Making accurate final impressions for complete den- tures is a multistep process that involves a preliminary impression, a custom-made final impression tray, and a border corrected final impression.2-4 Making preliminary impressions with modeling plastic impression compound can be t~me-co~~~g.3 Preliminary irreversible hydro- colloid impressions are often overextended, and final impression trays made on preliminary casts from these impressions require detailed border molding before the fi- nal impression is made4 Before the impression procedures are instituted, most complete denture and immediate den- ture patients would benefit from tissue-conditio~g pro- cedures.2-4

This procedure combines the use of tissue-conditioning, a preliminary functional impression made with a chairside short- term resilient reline material, a preliminary silicone putty diagnostic cast for pretreatment evaluation, diagno- sis and problem solvmg, and a precise final impression tray. The tray will not be overextended or require detailed border molding before the final impression is made.

=Assistant Professor, Department of Oral Health Practice. Copyright 0 1996 by The Editorial Council of THE JOURNAL OF

PROSTHETIC DENTISTRY.

0022-3913/96/$5.00 + 0. 10/l/70391

Fig. 1. Denture border shape showing periphery of func- tional impression equal to quality preliminary impression,

PROCEDURE

Make an initial evaluation of the health of the tissue. Observe the quality of the intaglio surface of the exist- ing denture and evaluate extension, fit, retention, sta- bihty, vertical dimension of occlusion, and occlusal plane. When tissue conditioning is indicated,5 relieve and modify the denture approp~ately. Make a mix of tissue-conditioning material (Coe- Comfort, GC America Inc., Chicago) according to the manufacturer’s directions and place it in the denture and border mold. Remove the old treatment material and repeat the procedure at regular intervals until the soft tissue has returned to a healthy con~tion. Remove the tissue-conditioning material, mix and place a chairside short-term resilient lining material ((Joe-Soft, GC America), and border mold it. This ma- terial creates a functional impression and provides the

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Fig. 2. Silicone putty adapted to intaglio surface and bor- ders of functional impression. Large paper clips used for retention to the stone.

Fig. 4. Indexed magnetic base allows easy removal and repositioning of cast onto articulator.

Fig. 3. Trimmed silicone diagnostic cast with existing denture removed.

desired intaglio surface detail and border extensions of a quality preliminary impression (Fig. 1).5 Remove the denture from the mouth and make a sil- icone putty diagnostic cast (Extrude Putty, Kerr U.S.A., Romulus, Mich.) directly inside the function- ally corrected dentures. Place large paper clips into the putty for retention to the stone base (Fig. 2).l The re- sulting silicone cast permits easy removal and reposi- tioning of the functionally relined denture (Fig. 3). Index the bottom ofthe cast. When desired, a magnetic split cast former (Great Lakes Orthodontics, LTD, Tonawanda, N.Y.) may be inserted into the dental stone before it sets. The magnetic system allows for easy removal and accurate repositioning of the cast (Fig. 4) in the articulator, which is helpful during later steps in the laboratory.

10.

11.

Make an arbitrary hinge axis face-bow transfer record and mount the maxillary silicone putty cast to the ar- ticulator. Make an interocclusal record with a material of choice at the desired vertical dimension of occlusion and mount the mandibular cast to the articulator. Use a semiadjustable articulator to make it easier to evalu- ate the interarch relationships and to complete prob- lem solving and treatment planning. Separate the indexed silicone putty diagnostic cast from the mounting stone and duplicate it in the labo- ratory with reversible hydrocolloid duplicating mate- rial and pour it in dental stone (Fig. 5).5 (The stone duplicate of the silicone putty cast is used to make a custom final impression tray.6 The peripheral roll on the stone cast represents the controlled extensions of a border-molded functional impression similar in qual- ity to a stone cast poured from a preliminary impres- sion made with modeling plastic impression com- pound.) Make a custom final impression tray (Fig. 6). It is ready for use without additional preimpression border molding. Make the final impression in the material and method of choice and make a master cast. A plaster of paris and pumice boxing method7 is recommended for the final impression (Fig. 7) and the use of dental stone (Micro- stone, Whip Mix, Corp., Louisville, KY.) to produce the master cast (Fig. 8).7

DISCUSSION

Altering the intaglio surface of the existing dentures with tissue-conditioning material improves the patient’s denture foundation and provides improved detail in the diagnostic silicone putty casts. The tissue-conditioning

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Fig. 5. Silicone diagnostic cast and stone cast made by duplicating.

Fig. 6. Custom impression tray ready for final impression without additional preimpres- sion border correction.

procedure also has diagnostic value when relining is being mercial dental laboratory, facilities are available to dupli- considered rather than remaking an immediate or exist- cate the silicone putty cast by use ofreversible bydrocolloid ing complete denture. A custom final impression tray can and dental stone. The stone cast that results from dupli- be made directly on the silicone putty cast, but it is more eating the preliminary silicone putty cast has proper difficult to adapt and maintain the position of the relief reproduction of the mucobuccal fold. Depending on the wax and the acrylic resin than when using a stone cast. material and procedure chosen for the final impression, an When the custom final impression tray is made in a com- excellent final impression tray can be made to expedite the

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Fig. 7. Final master impression embedded in plaster of Paris and pumice mixture and then boxed with wax.

Fig. 8. Master cast produced from described procedure.

final impression procedure. The resulting final impression is made with minimal chair time because of the quality of the final impression tray made from the stone duplicate of the silicone putty cast. These procedures are applicable for the immediate denture patient where pretreatment casts had overextended borders because of flared teeth and os- seous contours. The chairside reline with short-term resil- ient material provides an excellent preliminary functional impression when new dentures are indicated.

Silicone putty casts have been used for diagnostic proce-

duresl and duplicating procedure8 with existing complete dentures. The methods presented here combine the use of a functional impression procedure as a substitute for a preliminary impression, mounted diagnostic silicone putty cast, and the fabrication of a custom final impression tray. Eliminating the need for border molding before making the final impression simplifies the procedure when a predict- able final impression and quality master cast are made for complete denture patients.

REFERENCES

1. McCartney JW, Thompson GA, Goheen KL. Silicone putty diagnostic casts for edentulous patients wearing complete dentures. J PROSTHET DENT 1994;71:220-1.

2. Zarb GA, Bolender CL, Hickey JC, Carlsson GE. Boucher’s prosth- odontic treatment for edentulous patients. 10th ed. St. Louis: Mosby- Year Book, 1990:123-43.

3. Heartwell CM, Rahn AO. Syllabus of complete dentures. 4th ed. Phil- adelphia: Lea & Febiger, 1986:423-40.

4. Levin B. Impressions for complete dentures. Chicago: Quintessence, 1984:193-218.

5. Rudd KD, Morrow RM. Preliminary impressions. In: Morrow RM, Rudd KD, Rhoads JE, eds. Dental laboratory procedures: complete dentures. 2nd ed. St. Louis: CV Mosby, 1986;1:9-25.

6. Rudd KD, Morrow RM. Impression trays. In: Morrow RM, Rudd KD, Rhoads JE, eds. Dental laboratory procedures: complete dentures. 2nd ed. St. Louis: CV Mosby, 1986;1:26-56.

7. Rudd KD, Morrow RM. Final impressions. In: Morrow RM, Rudd KD, Rhoads JE, eds. Dental laboratory procedures: complete dentures. 2nd ed. St. Louis: CV Mosby, 1986;1:57-89.

8. Ansari IH. Duplicating an existing complete denture to make a replica. J PROSTHET DENT 1994;72:445-7.

Reprint requests to: DR. KEITH E. KINDERKNECHT COLLEGE OF DENTISTRY UNIVERSITY OF KENTUCKY CHANDLER MEDICAL CENTER, D-630 LEXINGTON, KY 40536-0084

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