Lakhasly

cast metal restoration is not ready for evaluation and cementation merely because it has been stripped of its investment. The unpolished surface is relatively rough, and a series of finishing procedures are needed to produce highly polished axial surfaces. Such surfaces limit the accumulation1,2 and retention3 of plaque and facilitate maintenance of health of the supporting periodontal tissues. The sprue needs to be removed, and the area of its attachment needs to be recontoured. Any nodules or other minor irregularities remaining on the cast surface must be eliminated.

Metal finishing for metal-ceramic restorations is similar to that for cast metal. The discussion in this chapter is applicable to both restoration types. In practice, the final polishing of metal-ceramic restorations is not done until after characterization and glazing (see Chapter 30).

OBJECTIVES AND PROCEDURES The objectives and procedures for finishing are different for each part of the cast restoration. The following discussion is sequentially divided into corresponding phases; each is identified as a zone (Fig. 29-1).

image Fig. 29-1 Recommended sequence for finishing of a cast restoration. All procedures for a zone should be completed before the next zone is started. Zone 1 is the internal margin; Zone 2, the internal surface; Zone 3, the sprue; Zone 4, the proximal contacts; Zone 5, the occlusal surface; Zone 6, the axial walls; and Zone 7, the external margins.

Zone 1: Internal Margin Objective To minimize any dissolution of the luting agent, a 1-mm-wide band of metal must be obtained that is closely adapted to the tooth surface.4 A defect within this zone can significantly reduce a restoration’s longevity. Good adaptation is obtained by carefully reflowing the wax pattern (Fig. 29-2). With careful standardization of technique, the dentist can achieve predictable and consistent results.

cast metal restoration is not ready for evaluation and cementation merely because it has been stripped of its investment. The unpolished surface is relatively rough, and a series of finishing procedures are needed to produce highly polished axial surfaces. Such surfaces limit the accumulation1,2 and retention3 of plaque and facilitate maintenance of health of the supporting periodontal tissues. The sprue needs to be removed, and the area of its attachment needs to be recontoured. Any nodules or other minor irregularities remaining on the cast surface must be eliminated.

Metal finishing for metal-ceramic restorations is similar to that for cast metal. The discussion in this chapter is applicable to both restoration types. In practice, the final polishing of metal-ceramic restorations is not done until after characterization and glazing (see Chapter 30).

OBJECTIVES AND PROCEDURES
The objectives and procedures for finishing are different for each part of the cast restoration. The following discussion is sequentially divided into corresponding phases; each is identified as a zone (Fig. 29-1).

image
Fig. 29-1 Recommended sequence for finishing of a cast restoration. All procedures for a zone should be completed before the next zone is started. Zone 1 is the internal margin; Zone 2, the internal surface; Zone 3, the sprue; Zone 4, the proximal contacts; Zone 5, the occlusal surface; Zone 6, the axial walls; and Zone 7, the external margins.

Zone 1: Internal Margin
Objective
To minimize any dissolution of the luting agent, a 1-mm-wide band of metal must be obtained that is closely adapted to the tooth surface.4 A defect within this zone can significantly reduce a restoration’s longevity. Good adaptation is obtained by carefully reflowing the wax pattern (Fig. 29-2). With careful standardization of technique, the dentist can achieve predictable and consistent results.