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Present (During Fixed

Past

Prosthodontic Therapy)

Caries

Preparation trauma

Operative dentistry

Microbial exposure

Bruxism

Desiccation

Periodontal surgery

Chemical exposure

Prosthodontic therapy

Thermal exposure

Sclerosis Dentinal Tubules

Fig. 15-2. Pulp trauma and exposure of the dentinal tubules from tooth preparation.

Fig. 15-2. Pulp trauma and exposure of the dentinal tubules from tooth preparation.

This is particularly important when the crown margin will be placed apical to the free gingival margin. 3 If the provisional restoration is inadequate and paèpecorilrol is impaired, gingival health will de-

The maintenance of good gingival health is always desirable, but it has special practical significance when fixed prosthodontics is undertaken. Inflamed or hemorrhagic gingival tissues make subsequent procedures (e.g., impression making and cementation) very difficult. The longer the provisional restoration must serve, the more significant become any deficiencies in its fit and contour (Fig. 15-3). When gingival tissue is impinged upon, ischemia is likely. This can be detected initially as tissue blanching. If it is not corrected, a localized inflammation or necrosis will develop.

Occlusal Compatibility and Tooth Position. The provisional restoration should establish or maintain proper contacts with adjacent and opposing teeth (Fig. 15-4). Inadequate contacts allow supraeruption and horizontal movement.

Supraeruption is detected at try-in when the definitive restoration makes premature contact. Correcting this in the operatory is possible, but the effort is time consuming and often leads to a restoration with poor occlusal form and function. Horizontal movement results in excessive or deficient proximal contacts. The former requires tedious chairside adjustment; the latter involves a laboratory procedure to add metal or ceramic to the deficient site. This often results in a compromised

Rough margins around provisionals will jeopardize subsequent procedures.

Fig. 15-3. A provisional restoration should have good marginal fit, proper contour, and a smooth surface finish. A, The properly contoured provisional. Smoothly continuous with the external surface of the tooth. B, Overcontour-ing. Irregular transition from the restoration to the root surface and inadequate marginal adaptation. These factors contribute to plaque accumulation and an unhealthy periodontium.

If a provisional does not ensure positional stability, tooth movement can occur, and additional treatment will be necessary.

Fig. 1 5-4, Proper occlusal and proximal contacts promote patient comfort and maintain tooth position.

A missing proximal contact allows tooth migration. The resulting root proximity may require surgical or orthodontic correction for impression making (see Fig. 6-26).

A missing proximal contact allows tooth migration. The resulting root proximity may require surgical or orthodontic correction for impression making (see Fig. 6-26).

Provisional Restoration

The provisional restoration must protect the tooth. Fracture of a tooth after the impression phase delays treatment and jeopardizes restorability.

The provisional restoration must protect the tooth. Fracture of a tooth after the impression phase delays treatment and jeopardizes restorability.

proximal contour. This, along with root proximity (Fig. 15-5), impairs oral hygiene measures.

Prevention of Enamel Fracture (Fig. 15-6). The provisional restoration should protect crown prepa-ratrnn margins. This is particularly true with partial-coverage designs in which the margin of the preparation is close to the occlusal surface of the tooth and could be damaged during chewing. Even a small chip of enamel will make the definitive restoration unsatisfactory and necessitate a time-consuming remake.

to improve strength
Overcontoured Crown

Areas of overcontouring

Fig. 15-7. The connectors of a provisional fixed partial denture are often purposely overcontoured. A, In the anterior region, the degree of overcontouring is substantially limited by esthetic requirements. B, In the posterior region, esthetics is less restrictive, but overcontouring still must not jeopardize maintenance of periodontal health.

Areas of overcontouring

Fig. 15-7. The connectors of a provisional fixed partial denture are often purposely overcontoured. A, In the anterior region, the degree of overcontouring is substantially limited by esthetic requirements. B, In the posterior region, esthetics is less restrictive, but overcontouring still must not jeopardize maintenance of periodontal health.

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