Stains of the Teeth
Stains are primarily esthetic problems and vary in type and difficulty of removal. Food, chemicals, and bacteria cause stains.
Stains of the teeth occur in three basic ways:
•Stain adheres directly to the surface of the tooth.
Before coronal polishing is undertaken to remove stains, it is important to distinguish between extrinsic and intrinsic stains.
Extrinsic stains are those that occur on the external surfaces of the teeth and may be removed by scaling and/or polishing (Table 18-3).
TABLE 18-3
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| Type of Stain | Appearance | Cause |
| Black stain | Thin black line on the teeth near the gingival margin; more common in girls | Caused by natural tendencies |
| Frequently found in clean mouths | ||
| Difficult to remove | ||
| Tobacco stain | A very tenacious dark brown or black stain | Caused by the products of coal tar in the tobacco and from the penetration of tobacco juices into pits and fissures, enamel, and dentin of the teeth. Use of any tobacco-containing products causes tobacco stains on the teeth and restorations. |
| Brown or yellow stain | Most commonly found on the buccal surfaces of the maxillary molars and the lingual surfaces of the lower anterior incisors | Caused by poor oral hygiene or use of a toothpaste with inadequate cleansing action |
| Green stain | Appears as a green or green-yellow stain, usually occurring on the facial surfaces of the maxillary anterior teeth | Caused by poor oral hygiene when bacteria or fungi are retained in the bacterial plaque |
| Most common stain in children | ||
| Antiplaque agents | Reddish-brown stain appears on the interproximal and cervical areas of the teeth. It can also appear on restorations, in plaque, and on the surface of the tongue. | Caused by the use of prescription mouth rinses that contain chlorhexidine. (Chlorhexidine is a disinfectant with broad antibacterial action.) |
| Food and drink | Light brownish stain. Stain is lessened with good oral hygiene. | Caused by tea, coffee, colas, soy sauce, berries, and other foodstuffs |
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Intrinsic stains are those that occur within the enamel and cannot be removed by polishing (Table 18-4). Intrinsic stains may be endogenous (occurring during tooth development), or they may be exogenous (occurring after eruption).
TABLE 18-4
| Type of Stain | Appearance | Cause |
| Pulpless teeth | Not all pulpless teeth discolor. A wide range of colors exists: light yellow, gray, reddish brown, dark brown, or black; sometimes an orange or greenish color is seen. | Blood and pulpal tissue break down as a result of bleeding in the pulp chamber, or death of the pulp tissue. Pigments from the blood and tissue penetrate the dentin and show through the enamel. |
| Tetracycline antibiotics | Light green to dark yellow or a gray-brown. Discoloration depends on the dosage, the length of time the drug was used, and the type of tetracycline. | Can occur in the child when the mother is given tetracycline during the third trimester of pregnancy or when given in infancy and early childhood |
| Dental fluorosis | Also termed “mottled enamel,” it results from ingestion of excessive fluoride during the mineralization period of tooth development. | Varying degrees of discoloration ranging from a few white spots to extensive white areas or distinct brown stains (Fluorosis is discussed and illustrated in Chapter 17.) |
| Imperfect tooth development | Teeth are yellowish-brown or gray-brown. Teeth appear translucent or opalescent and vary in color. | May result from genetic abnormality or environmental influences during development |
| Silver amalgam | Appears as a gray or black discoloration around a restoration | Metallic ions from the amalgam penetrate into the dentin and enamel. |
| Other systemic causes | Appears as a yellowish or greenish discoloration in the teeth | Conditions of prolonged jaundice early in life and erythroblastosis fetalis (Rh incompatibility) |
Methods of Removing Plaque and Stain
Every stain removal technique has the potential for damage by removing a small amount of enamel from the surfaces of the teeth being polished. There is also the potential for injury to the gingivae; therefore these techniques must always be carried out with the utmost caution.
Two methods of stain removal are air-powder polishing and the rubber cup polishing technique.
Remember, you must check the regulations in your state to see if coronal polishing can be delegated to a qualified dental assistant, and if so, which technique is permitted.
Air-Powder Polishing
The air-powder polishing technique uses a specially designed handpiece with a nozzle that delivers a high-pressure stream of warm water and sodium bicarbonate. The powder and water, under high pressure, remove stain rapidly and efficiently; the flow rate is adjusted to control the rate of abrasion.
Rubber Cup Polishing
Rubber cup polishing is the most common technique for removing stains and plaque and for polishing teeth. An abrasive polishing agent is placed in a rubber polishing cup that is rotated slowly and carefully by a prophy angle attached to the slow-speed handpiece. This is the form of coronal polishing that is described in this chapter.
