An impression technique for immediate dentures

Complete dentures

An impression

technique

Sebastian

J. Campagna,

Letterman

General Hospital,

Colonel,

for immediate DC,

.Can Fratksco,

dentures

USA*

Calif.

F

inal impressions for immediate dentures are made by- using many combinations of materials and methods. These vary from Alginate (irreversible hydrocolloid) in stock trays to sectional impressions made in a number of different materials. The irreversible hydrocolloids arc probably the most widely used but are the poorest materials for making final immediate denture impressions. This is due to the tendency of the impression material to displace tissues throughout the area of unattached mucosa. In this situation, the displaced tissue may resume its normal configuration, which either overcomes the border seal or, if the dcnturc remains scatcd, irritates the border mucosa. The dentist may spend more time attempting to adjust the denture than he spends in making the original impression. As a result, all semblance of the part of the physiologic adaptation is lost. When this technique is rmployed, mouth that causes the most difficulty is the anterior region around the remaining teeth, Ideally, the impression should reach the mucolabial reflection, but if it is overextended, the labial flange of the denture may dislodge the denture and may become a source of irritation and, frequently, is quite unesthetic. On the. other hand, sectional impressions made with a zinc-oxide and eugenol with paste or rubber base impression material in a custom tray, in correlation Alginate, avoid many of the problems mentioned above. However, in most of the techniques for sectional impression making, the labial flange is overextended; the reason for this is that the custom tray does not include the ‘anterior part of the dental arch but is trimmed so it is distal to the remaining anterior teeth. Physiologic bordermolding of the tissue in the anterior region is most difficult when the second part of the sectional impression is made, regardless of the kind of impression material used. Furthermore, consideration of facial contour must begin in the impression stage of denture construction. Therefore, the thickness and length of the anterior flange of the impression must be controlled. This is most difficult without a border molding tray. Normally, all posterior teeth should be removed before the impressions are made. Read before the Pacific Coast Society of Prosthodontists in Sun Valley, *Chief, Removable Prosthodontics Service, Department of Dentistry. 196

Idaho.

Impression technique for dentures

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197

A well-healed posterior ridge will make possible a more accurate tissue-to-base relationship in the completed denture, more comfort for the patient, and a longer period of denture stability while the surgical site heals. However, if the patient’s occlusal vertical dimension is to be maintained, it is preferable to retain an occluding premolar along with the six anterior teeth. This eliminates the “scientific guess” of determining the occlusal vertical dimension and simplifies the entire procedure. If the patient will not receive his denture for an unusually long period of time, an occluding posterior tooth should not be retained because of the possibility of occlusal trauma and because the tooth is a potential source of pathosis and pain. If an occluding posterior tooth is not to be retained, a pre-extraction record, such as a profile x-ray, is useful in determining vertical dimension of occlusion. Diagnostic casts of both arches are desirable for recording the tooth size, form, and position, and a record of the color of the teeth should be made before the teeth are removed. THE IMPRESSION

TECHNIQUE

Preliminary impressions are made in a reversible hydrocolloid in a stock tray. These impressions are a fairly accurate record of the attached gingival tissues with

Fig. 1. An indelible pencil attached and free tissues.

line is drawn

on the preliminary

impression

at the junction

of the

19%

J. Pros.Dent.

Campagla

Scptemhrr,

1968

the free mucosal tissue displaced. An indelible pencil line is drawn on the impression (Fig. 1 j approximately at the junction of the attached and free tissues. This lint will transfer to the cast when the impression is ymrccl. Normal Iy, it represents ;L borclcl~ extension approximately 2 to 3 mm. short of rcaching the rnucobuccal reflection. ‘fllc cast is poured and the indelible lint is transferred to the cast and is darkened I)!. retracing. THE ACRYLIC

RESIN TRAY

The undercuts in the cast are blocked out (Fig. 2)) and a strip of “beading lvax” is placed at the gingival margins of the remaining teeth : no shim is employed ) A tinfoil substitute* is painted on the cast and is allowed to dry. With cold-curing acrylic resin, a custom impression tray is made by the “sprinkle on” technique. This allows only rninimal lvarpage and per-mits a relatively accurate adaptation of thr: base to the attached mucosa. The tray is cured under 20 pounds of pressure in a pressure cooker and is removed from the cast. Then, the borders are trimmed to the indelible lint on the cast. It’ax occlusion rims are adapted to the part of the tra? covering the edentlrlou5 ridges (Fig. 3, A and B) . These rims serve as handles while and also scrvc to simulate the 1)osterior teeth and I-estric.t the final illipression is rnadc the movements of tlrc check to the same extent as the finished dentures. The acrylic resin tray is seated in the mouth and adjusted so the borders are 2 to 3 mm. short of reaching the unstrained tissue reflection of the mltcobuccal fold, and 2 to 3 mm, short of the gingival margins around the remaining teeth. The tray is “Modern Foil. Modern Materials Mfg. Company, St. Louis, MO.

Fig. 2. ?‘he undercuts are blocked out on the cast.

Volume 20 Number 3

Impression

checked for ease of insertion and removal to eliminate teeth, and necessary adjustments are made. BORDER-MOLDING

technique binding

for

dentures

199

against the remaining

THE TRAY

After the resin tray is adjusted, green stick compound is added to the borders, and the tray is border-molded. The important phase of this technique is the tissue placement, i.e., the extension of the borders of the tray so they make adequate contact with the reflecting tissues. This gains a border seal with minimal displacement of the

A

B

Fig. 3. (A) Posterior occlusion rims are built on the acrylic has been removed from the cast.

resin impression

tray. (B) The tray

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J. Pros. Dent. September, 1968

Carnpagna

soft tissue and with a functional adaptation to the patient’s jaw and soft tissue movements. In the border-molding, it is often necessary to manually move the upper lip in order to avoid impingement upon the labial frenum. The anterior region in the impression is the most perplexing part of the immediate denture. The impression must reach to the reflecting tissues to gain a seal, but it must not be overextended. Facial contour must be considered at this stage. If the dentist determines a need for fullness at this stage, the upper lip is partially developed by thickcbning the compound roll on the border of the tray. However, the \-ertical extension should not be altered. Normally, the border roll of the anterior re$on of an irnmediate denture should be narrower than that of a maxillary complete dcnturc:, because no recession has yet taken place, and the lip has not atrophied. The thickness and length of the labial flange are of great importance both functionally and esthetically, especially in thr first few days following surgery. Here are some fundamentals in this impression technique that must be followed (Fig. 4) : (1) re 1ie f must be provided for the labial and buccal frenum attachments; (2) relief should be p rovided in the zygomatic arch region if it is hard and is covered only by a thin layer of soft tissue ; (3) maximum coverage should be made in the buccal vestibule with consideration for and molding to the movement of the coronoid process and the insertion of the temporalis muscle; (4) at the distal border, the flange should extend into the hamular notch (this is important for a satisfactor) border seal, but there should be no extension distal to the notch) ; (5) the posterior border of the denture should h(: on the soft tissue overlying the bone hard palate, (generally, it will be on or slightly posterior to the vibrating or flexure line depending on the palatal \.ault, on the amount of soft tissue present, and on the drop of the soft palate) ; and (6‘1 the midpalatal aria should be palpated to determine whether relief is necessary. If the midpalatal I-ault is hard? convex3 and covered with a thin

resin impression tray has been border-molded The opening allows the tray to pass over the remaining teeth.

Fig. 4. The acrylic

with

green stick compound.

yl$er

u

‘3”

Impression technique for dentures

201

layer of soft tissue, relief is indicated. The palatal relief technique advocated by Jordan1 may be used. After the border-molding is completed, the surface of the compound is lightly scraped with a blade to insure against pressure areas. This is especially important in the buccal vestibule and in the region of the remaining anterior teeth where severe undercuts may be present. Further relief for frenum attachments are made at this time, and the tray is checked in the mouth for assurance that it does not bind upon insertion, With a No. 6 round bur, holes are drilled through the palatal part of the

Fig. 5

Fig. 6

Fig. 5. The main part of the final impression is trimmed to reestablish a sharp demarcation pression tray.

is made in a zinc-oxide and eugenol paste and line at the original opening through the im-

Fig. 6. The Alginate (irreversible hydrocolloid) impression of the remaining anterior teeth is made while the main part of the impression is seated in the mouth. This establishes the relationship of the remaining teeth to the final impression and completes the impression.

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J. Pros. Dent. September, 1968

Canzpagna

impression tray in the region of the prrruolars and molar~s. This allows for a free flow of the impression material to the lirr,gual and buccal sides of the ridge. ‘I’hese holes will keep the hydrostatic pressure to a minim~un wllen the final impression is made. Rubber base adhesive is a.ppliecl to the resin tray and to the modeling compound border and is allowed to dry. A rubber base impression material is employed for perfecting the main part of the impression. It allow the impression to be removed from selvere undercuts Lvhich exist in the region of the anterior part of the arch of immediate denture patients. The impression material is mixed according to the manufacturer’s directions and is inserted in the tray. The impression is made with the impression tray seated in the mouth in the same position it occupied when it was border-molded. After removal from the mouth, the impression is usually covered with a thin flash of rubber that has flowed over the gingival parts of the remaining anterior teeth. This excess material is carefully trimmed away with scissors to reestablish a sharp demarcation line at the original opening through the impression tray (Fig. 5%). IMPRESSION

OF THE REMAINING

TEETH

The tray with the impression rubber lining is reseated in the mouth and checked for stability. Alginate (irreversible hydrocolloid) impression material is applied over the remaining teeth and the exposed gingival tissues. With the same material in a stock tray, an over-all irnpressioti is made of the remaining teeth, and the final impression is seated in the mouth. Very little pressure is applied on this impression tray when the impression is made, The purpose of the impression is to record the shape of the anterior teeth and their relationship to the final impression of the palatal and edentulous regions (Fig. 6). The irreversible hydrocolloid impression material should not extend beyond the established borders of the final impression. If, however, overextension occurs, it may be easily cut away without interference with the established denture border. The final impression is boxed, and a stone cast is poured into it in the usual manner. DISCUSSION Various muscles have fibers extending into the orbicularis oris, and some of these muscles have bony origins. These extensions into the orbicularis oris muscle and the modiolus at the angle of the mouth make them extremely important in denture construction. Their support or insertion and, consequently, their action is dependent upon the1 position of the natural teeth. Swenson” states; “The proper width of the denture border in the posterior and anterior regions of the maxillary denture plays a great part in supporting the muscles and lengthening the distance that these muscles must stretch to reach their insertions.” SUMMARY This article describes an immediate maxillary denture impression technique. The technique assures the same degree of accuracy of the borders in the dentulous region as in edentulous maxillary dental arches. It insures complete physiologic adaptation

Volume 20 Number 3

Impression

of the denture base throughout soft tissue trauma.

technique

the basal seat and produces

for dentures

minimal

203

postoperative

References 1. Jordan, L. G.: Company. 2. Boucher, C. 0.: Company.

Dentistry.

A Digest

Swenson’s

Complete

DEPARTMENT OF DENTISTRY LETTERMAN GENERAL HOSPITAL SAN FRANCISCO, CALIF. 94129

of

Practice,

Dentures,

Philadelphia,

ed. 5, St. Louis,

1941,

J. B. Lippincott

1964, The C. V. Mosby