TEETH BLEACHING - TETRACYCLINE

TETRACYCLINE

Tetracycline is a broad-spectrum bacteriostatic antibiotic (van der Bijl and Ptitgoi-Aron 1995) which is used to treat a variety of infections. The tetracycline antibiotics are a group of related compounds that are effective against Gram negative and Gram positive

bacteria. It is well known that the administration of tetracycline during odontogenesis causes unsightly discoloration of both primary and secondary dentitions. The discoloration varies according to the type of tetracycline used (see Table 1.2). The staining effects are a result of chelation of the tetracycline molecule with calcium ions in hvdroxvapatite crystals, primarily in the "dentiJ1e (S'wift 1988). The tetracycline is incorporated into the enamel and dentine. The chela ted molecule arrives a t the mineralizing predentine-dentine junction via the terminal capillaries of the dental pulp (Patel et aI1998). The brown discoloration is due to photooxidation, which occurs on exposure of the tooth to light.

The staining can be classified according to the developmental stage, banding and colour (Jordan and Boksman 1984):

- First degree (mild tetracycline staining) is yellow to grey, which is uniformly spread through the tooth. There is no banding .

- Second degree (moderate staining) is vellow-brown to dark grey .

- Third degree (severe staining) is blue-grey or black and is accompanied by significant banding across the tooth .

-Fourth degree (intractable staining) has been suggested by Feinman et al (1987), designated for those stains that are so dark that bleaching is ineffective .

All degrees of stain become more intense on chronic exposure to artificial light and sunlight, The severity of pigmentation depends on three factors: time and duration of administration, the type of tetracycline administered, and the dosage (Shearer 1991, Dayan et al 1983).

First and second degree staining are normally amenable to bleaching treatments (Haywood 1997). Prolonged home bleaching has been reported in the literature to be successful for tetracycline cases. This may take between three and six months or longer . The bleaching material penetrates into the dentine structure of the tooth and causes a penl1anent colour change in the dentine colour (McCaslin et al 1.999).