Teeth, tetracycline staining

Teeth have a transparent outer layer of enamel which is about 2 mm thick, and an inner layer of white dentine which surrounds the innermost pulp cavity where the nerves are located. Both the enamel and the dentine are calcium phosphate, a mineral that can exist in various forms, that of the enamel layer being hydroxyapatite, which is one of the hardest naturally occurring minerals. When this is exposed to fluoride it forms an even harder mineral fluoroapatite. Unfortunately both this and hydroxyapatite are slightly porous and this is why teeth become stained by chemicals such as polyphenols and other dark coloured substances that are present in coffee, tea, red wine, bilberries, blueberries, and cigarette smoke. (Staining can also be caused by tetracycline antibiotics, especially when taken by children whose teeth are developing. This type of discoloration is permanent, which is why such antibiotics are now only prescribed for adults.)... 

Abou-Rass M. Long-term prognosis of intentional endodontics and internal bleaching of tetracycline-stained teeth. Compend Contin Educ Dent 1998 19(10) 1034-8, 1040-2, 1044. 

Kinoshita J, Jafarzadeh H, Forghani M. Vital bleaching of tetracycline-stained teeth by using KTP laser a case report. Eur J Dent 2009 3(3) 229-32. 

Probably the most well-known unwanted effect of tetracyclines is the discolouration and damage of the deciduous and also the permanent teeth during the process of their calcification. For this reason tetracyclines have to be avoided in ehildhood, if possible, from the fourth month in utero until the 8th year of age. Reports concerning the frequency of this side effect continue to appear. Of 965 5-year-old children in Jerusalem 8% possessed tetracycline-stained teeth (61 ). In Bulgaria discolouration of the hard dental tissues was seen in 29% of 1018 children aged 3—7 years, all of the affected children having been treated with tetracycline during the first year of life (62 ). 

Zadik, D. and Eidelman, E. (1975) Tetracycline-stained teeth in Jerusalem preschool children. Community Dent. Oral Epidemiol, 3, 69. 

Tetracyclines are used as alternative dnigs in a variety of circumstances when the patient is unable to take the dnig of choice, eg, in patients allergic to penicillin (88,89). Tetracyclines are widely known to cause staining of teeth (and are therefore contra-indicated in children developing permanent teeth), photosensitivity, and, in the case of minocycline, vestibular toxicity. Details of these adverse effects and others associated with administration of tetracyclines have been comprehensively reviewed (96—101). 

The answer is c. (Hardman, pp 1134-1135.) Hematologic toxicity is by far the most important adverse effect of chloramphenicol The toxicity consists of two types (1) bone marrow depression (common) and (2) aplastic anemia (rare) Chloramphenicol can produce a potentially fatal toxic reaction, the gray baby syndrome, caused by diminished ability of neonates to conjugate chloramphenicol with resultant high serum concentrations. Tetracyclines produce staining of the teeth and phototoxicity... 

Tetracycline Moderate Possibility of permanent staining of developing teeth in the infant. Should be avoided during lactation. 

Sanchez AR, Rogers RS, 3rd, Sheridan PJ. Tetracycline and other tetracycline-derivative staining of the teeth and oral cavity, lnt J Dermatol. 2004 43 709-715. 

Staining of permanent teeth by tetracyclines takes place during tooth development by well-documented mechanisms. Tetracycline forms a complex with calcium orthophosphate during calcification, which then darkens with exposure to light. With minocycline, however, the staining occurs after eruption in previously normal-colored, fully mineralized adult teeth. For example, adult-onset tooth discoloration coincident with minocycUne administration occurred in four of 72 patients (7). 

Tetracyclines are also contraindicated in pregnant women, nursing mothers, and children younger than 8 years of age because they can cause dental staining and defects in enamelization of deciduous and permanent teeth, as well as a decrease in bone growth. "... 

Rickettsial Infections Tetracyclines may be life-saving in rickettsial infections, including Rocky Mountain spotted fever, recrudescent epidemic typhus, scrub typhus, rickettsialpox, and Q fever. Improvement often is evident within 24 hours. Doxycycline is the drug of choice for suspected or proven Rocky Mountain spotted fever in adults and children, including those <9 years of age, in whom the risk of staining of teeth is outweighed by the seriousness of the potentially fatal infection. 

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