TEETH BLEACHING- ILLNESS AND TRAUMA DURING TOOTH FORMATION

ILLNESS AND TRAUMA DURING TOOTH FORMATION 

TIle effects of illness, trauma and medica tion (e.g. porphyria, infant jaundice, vitamin deficiency, pheny j ketonuria, haematological anaemia) cumulative effect creating stains and defects, which cannot be altered by bleaching. Staining may result from haematological disorders such as erythroblastosis foetalis (Atasu et al 1998), porphyria, phenylketonuria, haemolytic anaemic, sickle cell anaemia and thalassaernia. As the coagulation system is affected, discoloration occurs due to the presence of blood within the dentinal tubules (Nathoo 1997). Bilirubinaemia in patients with liver dysfunction can cause bilirubin pigmentation in deciduous teeth (Watanabe et al1999).

STAINS AFTER ODONTOGENESIS 

(POSTERUPTIVE)

MINOCYCLINE 

Minocycline is a semisynthetic second-generation tetracydine derivative (Goldstein 1998). It is. a broad-spectrum antibiotic that is highly plasma bound and lipophilic (McKenna et at 1999). It is bact

antimicrobial activity than tetracycline or its analogues (Salman et al1985). The drug is used to treat acne and various infections. Its lipophilicity facilitates penetration into body fluids, and after oral administration the minocycline concentration in saliva is 30 to 6001;) of the serum concentration (McKenna et al 1999). Minocycline is absorbed from the gastrointestinal tract and combines poorly with calcium.

Those adolescents and adults who take the drug are at risk from developing intrinsic staining on their teeth, gingivae, oral mucosa and bones (Bowles and Bokmeyer 1997). It causes tooth discoloration by cheJating with iron to form insoluble complexes. It is also thought that the discoloration may be due to its forming a complex with secondary dentine (Salman et al 1985). The discoloration does not resolve after discontinuation of therapy.

The resultant staining is normally milder than that from tetracycline and may be amenable to bleaching and lightening, although it is case specific.

PULPAL CHANGES 

Pulp necrosis 

This can be the result of bacterial, mechanical or chemical irritation to the pulp. Substances can enter the dentinal tubules and cause the teeth to discolour. These teeth will require endodontic treatment prior to bleaching, the latter using the intracoronal method (see Chapter 8) or the outside/Inside technique (see Chapter 9).

Intrapulpal haemorrhage due to trauma Accidental injury to the tooth can cause pulpal and dentinal degenerative changes that alter the colour of the teeth (see Figure 1.14). Pulpal haemorrhage may occur giving the tooth a grey, non-vital appearance (Nathanson and Parra 1987). The discoloration is due to the haemorrhage, which causes lysis of red blood cells. Blood disintegration products such as iron sulphides enter the dentine tubules and discolour the surrounding dentine, which causes discoloration of the tooth (Baratieri et al 1995). Sometimes the tooth can recover from such an episode (Marin et al 1997) and the discoloration can reverse naturally without bleaching. These discoloured teeth should be vitality tested, because those that are still vital (see Chapter 4) can be successfully bleached using the home bleaching technique (see Chapter 5).

Dentine hypercalcification 

This results when there is excessive irregular dentine in the pulp chamber and. canal walls. There may be a temporary disruption in blood supply followed by the disruption of odontoblasts (Rotste.in 1998). Irregular dentine is laid down in the walls of the pulp chamber. There is a gradual decrease in the translucency of these teeth which results in a yellowish or yellow-brown discoloration. These teeth can be bleached with good results (see Chapter 9).