TEMPORIZATION

INTERIM COVERING

Proper occlusal and proximal contacts

to promote patient comfort and maintain tooth position.

Proper occlusal and proximal contacts

to promote patient comfort and maintain tooth position.

The placement of an interim covering on a tooth after preparation is a biologic mandate to maintain vitality.

There are three major problems commonly associated with the clinical fabrication of temporary crown:

1. The time involvement necessary for the fabrication of adequate interim tooth coverage is underestimated by the majority of the dentists.

2. Treatment coverage is not always replaced by permanent restorations within the shortest possible time.

3. There are presently no inexpensive, tissue compatible materials that are fabricated by the dentist.

***One possible measure to combat these problems is to increase the length of the appointments to prevent hastily constructed treatment restoration.

Another is to program and coordinate appointment dates with lab services to accelerate the date of insertion of the final restorations.

8 Cardinal Requirements for Temporization:

1. The pulp of the tooth must be insulated from all forms of adverse stimuli.

2. Arch position of the prepared teeth should be maintained and stabilized to prevent extrusion of teeth and promote the accuracy of the impression.

3. Treatment restorations should not impinge the gingival tissues causing inflammation and tissue recession.

4. It should appear reasonably esthetic, particularly in the incisor and premolar areas.

5. Treatment restorations should develop occlusal function to assist in the establishment of a satisfactory maxillo-mandibular relationship.

6. It should also possess sufficient inherent strength to withstand light forces of occlusion.

7. It should be fabricated in such a manner to permit the patient to keep the area clean and serve as a healing matrix to tissues surrounding prepared teeth and edentulous areas.

8. Construction techniques should be within the realm of the average dentist and also capable of being easily removed with minimal damage to the teeth and supportive tissues.

Types of Temporary Crowns:

Metal (precious and non-precious) and Non-metal Materials

Nickel-Chromium crown

Extensively damaged primary teeth

May be applied to secondary teeth but are more suitable to primary teeth

Very hard

Aluminum shell crown

Restricted to PM and M area

Possess a consis-tency that permits a definite amount of molding to a px’s occlusion, but lacks the rigidity for acceptable marginal strength and proximal contacts

NON-ANATOMIC

ANATOMIC

Preformed commercial metal crown

Employed primarily in the posterior teeth

Excessive irritation or recession can be prevented by contouring of the gingival margins

Time saving aspect is the most attractive feature of this type of temporary crown

Cellulose acetate crown form Cellulose acetate

crown form consists of thin, soft, and transparent material. Sizes and shape can be selected from a mold guide. The crown form is trimmed and festooned to fit the preparation without impingement on the soft tissue.

Preformed polycarbonate anteriors Polycarbonate crown

forms are more tolerable, selected to establish contact areas

***Polycarbonate crown form remains on the prepared tooth, whereas the cellulose crown matrix is removed prior to cementation.

Heat-cured resins for bridges

Used when multiple preparations are involved

Teeth are reduced on a 2nd set of dx casts to simulate tooth prep, places the desired occlusion and contact areas on mounted models

Wax is boiled off and heat-cured temporaries are fabricated

Need only slight modification prior to interim cementation

Cold-cure alginate impression technique

An alginate impression of the teeth is taken on the day of the preparations are made but before any reduction of teeth

Alginate impres-sion is set aside and kept in a damp environment to prevent excessive distortion

After the prep., resin mixture is placed on the alginate impression corresponding to the crown prep.

Alginate impression with the resin mixture is placed back into the mouth

Impression is removed just prior to the rigid set of the acrylic

Template technique

Stone models of both arches are used prior to mouth prep.

Constructed with the aid of a thermal vacuum machine that adapts a plastic sheet over the entire stone cast

Plastic sheet is trimmed around the teeth to be prepared

Post-crown technique

A wire or non-precious metal post is adapted to the canal. The selected crown form is then filled with an acrylic resin and placed over the post, including a portion of the radicular surface of the tooth.

After sufficient polymerization has taken place, the crown is removed along with the temporary post, which is set within the resin

Limitations of Temporization:

Lack of inherent strength Poor marginal adaptation Color instability Poor wear properties Inadequate bonding characteristics Poor tissue response to irritation Arduous cement removal Detectable odor emission

Uses of Temporary Crowns1. Serves as a healing matrix for the

gingival tissue

2. Serve as a predictor of the final result

3. Serve as an oral hygiene training device

4. Provide security and comfort to the patient while the final restoration is being fabricated.

5. Saves considerable time at each subsequent appointment, during which castings are fitted, joints are soldered and porcelain is adapted prior to the final delivery

Try in of temporary crown

Make the necessary adjustments

Polish the crown before cementation