Selective polishing means that only those teeth or surfaces with stain are polished. This is done to avoid removing small amounts of enamel from the surface of the tooth with the abrasive agent during coronal polishing. The principle of selective polishing is to refrain from polishing unless necessary. The needs of the patient must always be reviewed before stain removal is performed (Table 18-2 and Box 18-1).

Soft, webbed polishing cups are used to clean and polish the smooth surfaces of the teeth (Figure 18-1). The polishing cup is attached to the reusable prophy angle by a snap-on or screw-on attachment.

Polishing cups are made from both natural and synthetic rubber. Natural rubber polishing cups are more resilient and do not stain the teeth. Synthetic rubber polishing cups are stiffer than natural polishing cups. If synthetic polishing cups are used, white synthetic cups are preferable because black synthetic cups may stain the teeth. Synthetic polishing cups should be used for patients with an allergy to latex products.

The prophylaxis angle, commonly called a prophy angle, attaches to the slow-speed handpiece (see Chapter 19). The reusable prophy angle must be properly cleaned and sterilized after each use. (Handpiece maintenance is discussed in Chapter 19.) When attaching the polishing cup or brush to the reusable type of prophy angle, be certain that the polishing cup or brush is securely fastened. If a polishing cup or brush falls off during the procedure, the patient could swallow or inhale it.

A disposable angle is available that is discarded after a single use. This disposable angle is manufactured with a polishing cup or a brush already attached.

The handpiece and prophylaxis angle are held in a pen grasp with the handle resting in the V-shaped area of the hand between the thumb and index finger (Figure 18-2). A proper grasp is important because if the grasp is not secure and comfortable, the weight and balance of the handpiece can cause hand and wrist fatigue (Box 18-2).

The fulcrum is repositioned throughout the procedure as necessary. The fulcrum may be intraoral or extraoral, depending on a variety of circumstances such as:

Improper movement of the hand and fingers greatly increases operatory fatigue and over time can cause painful inflammation of the ligaments and nerves of the wrist.

Bristle brushes are made from natural or synthetic materials and may be used to remove stains from deep pits and fissures of the enamel surfaces. Bristle brushes can cause severe gingival lacerations and must be used with special care (Box 18-3). Brushes are not recommended for use on exposed cementum or dentin because these surfaces are soft and are easily abraded.

Even a fine-grit abrasive agent removes small amounts of the enamel surface. Therefore the goal is to always use the abrasive agent that produces the least amount of abrasion to the tooth surface (Box 18-4).

Abrasives are available in commercial premixed pastes or in powders that are mixed with water or mouthwash to form slurry used in the polishing cup. Powder abrasives should be as wet as possible (but not runny) to minimize frictional heat. If the mixture is too wet, there will be splatter and difficulty in keeping the material in the cup. The commercial type of premixed paste is packaged ready to use.

Table 18-5 contains some of the most commonly used dental abrasives.