Esthetic Dentistry

Tooth discoloration resulting from long-term tetracycline therapy:a case reportJane A. Chiappinelli* / Richard E. Walton**

Administration of tetracycline to children or pregnant women is known to adverselyaffeet the color of developing teeth. This case report suggests the possibility thatdicotoration from tetracycline may not be limited to tooth development in the child,but may also affect the adult dentition. When given over long periods of time in adults,the tetracycline molecule is incorporated into the continuously forming secondarydentin. It is possible that chronic sun exposure of the incorporated tetracycline maycause the formation of a reddish-purple oxidation product, resulting in discolorationof the permanent teeth. (Quintessence Int 1992:23:539-541.)

Introduction

Administration of tetracycline during permanent tootbformation and up to 7 years of age often may result inmarked discoloration of the dentition.' Adult-onsettooth discoloration has been reported as a result ofminocycline therapy.-"' Minocycline is a derivative oftetracycline hydrochloride (HCI) with a slightly differentchemical structure.' These effects may not be limitedto minocycline; a case report will be presented thatsuggests the possibility of adult-onset tooth discolora-tion from iong-term ingestion of tetracycline.

Mechanism of action

Tetracycline travels in the blood to the coronal portionof the pulp, where there is an extensive vascular net-work. It is carried through the branching capillaries

' Former Graduate Student. Deparlmeni of Endodontics, Uni-veisily of Iowa, College of Dentistry, towa Ciiy, Ioiva 52242.

*• Professor and Chairman, Deparlmeni of Endodontics, Univer-sity of Iowa.

Address all correspondence to Dr Jane Chiappinellj, 1511 Devon-shire Court, Champaign, fllinois 61821.

of the subodontoblastic area to the terminal loops,which extend upward between the odontoblasts to endin the predentin."" The tetracycline molecule trans-ported to this area is believed to bond chemically tocalcium ions. This diffuses into the tissues to the siteof mineralization of the dentin, which is the junctionof predentin and dentin.' Thus a stable tetracycline-calcium orthophosphate complex is formed."

When tetracychne is first incorporated into the den-tin, it exhibits a yellow fluorescence under ultraviolet(UV) light.''"' This fluorescence gradually disappearsand the tooth discoloration reportedly changes fromyellow to brownish colors in children: this change islikely due to an oxidation product of tetracychne,which is light induced.** This was confirmed in an in vitrostudy, in which Davies et al" showed that, when tet-racycline is bound to hydroxy I apatite, it gives a brightyellow fluorescence when exposed to UV hght. Whenthe tetracycline is exposed to UV radiation, thefluorescence disappears with the formation of a reddish-purple material, which was determined to be4, 12-anhydro-4-oxo-4-dedimethylaminotetracycline(AODTC)." This might explain the gradual colorchange in children's teeth as they age as well as thedarkening of teeth in adults who are administered tet-racycline over long periods of time and also experi-ence chronic exposure to the sun.

Quintessence Internationai Voiume 23, Number 8/1992 539

Esthetic Dentistry

Fig 1 Dentition of 39-year-old woman with a history of 12years of tetracycline ingesf ion.

Case report

A 39-year-old white woman presented for root canaltreatment of her maxillary left first molar. While givingher medical history prior to treatment, the patient re-ported acne, for which she had taken oral letracyclinefor about 10 years. Her medical status was otherwiseunremarkahle. Later documentation from her phar-macy confirmed that she had been prescribed 250 mgof tetracychne IICI (Sumycin, Squibb), two capsulesper day, for the past 12 years. The patient worked as amail carrier and had experienced some facial photo-sensitivity, which had been controlled by sunscreenapplicafion.

The patient remarked that her teeth had becomedarker over time, but was unsure of onset. In addi-tion, she had noticed that her teeth were much darkerthan those of her sister, who was 2 years older. Thepatient did not recall tooth discoloration as a child ortaking tetracycline in childhood.

Visual examination revealed a blue-grey discolora-tion in the incisai one half to two thirds of the teeth(Eig I). Both the maxillary and mandibular teeth wereaffected. The stain was particularly noticeable in theanterior region. No abnormal pigmentation of the gin-giva was apparent.

Root canal treatment of the molar was completeduneventfully. Treatment options for correction of thetooth discoloration were presented and discussed withthe patient. Options included (I) root canal therapy ofsix anterior teeth in conjunction with internal bleach-ing, (2) placement of laminate veneers, and (3) notreatment. The patient opted for no treatment at pres-ent.

Di.scussiün

Although the literature relates the discoloring effect ofniinocycline on mature, fully developed teeth, " thereare no reported cases of adult-onset discolorationcaused by tetracychne HCI. However, in many of thecases of discoloration, both tetracycline and minocy-eline were given to the patients at various times; eitheror both drugs forms may have contributed to the dis-coloration. The adverse appearance of the teeth andthe gradual onset of discoloration in this patient wassimilar to other cases in the medical literature ofminocycline-associated tooth discoloration in adults,"suggesting a potential disadvantage to long-term tet-racycline therapy. It is a possibility that the undesirablecosmetic appearance of the acne may be exchangedfor permanent discoloration of the adult dentition,particularly if the patient experiences chronic sunexposure and ingests the tetracycline for prolongedperiods of time.

Treatment of tetracycline discoloration is challeng-ing. These teeth cannot be successfully bleached exter-nally, because the greyish stain is concentrated in theinaccessible primary inner layer of the secondary den-tin. External bleaching may temporarily lighten theenamel surface, but the result does not persist.'^ How-ever, elective root canal therapy followed by internalbleaehing will successfully and permanently bleach theteeth.'•'"'^ The major drawback of this treatment ap-proach is that control over the color change achievedis incomplete. In addition, unless all affected teeth aretreated, there is a sudden color transition between thebleached and unbleached teeth. Application of veneersmay provide a more predictable esthetic result, butthey also must be applied to all visible teeth and willusually require replacement, particularly in young in-dividuals. Lin et al,"' in an in vivo study, explored thenovel approach of photobleaching the dentin by irradi-ation with light sources that produce shortwave UVlight. As yet, this technique is experimental, but showspromise with the development of other sources ofshortwave UV light, such as UV lasers.

At this time the best solution is not treatment, butprevention. When causes of this discoloration are un-derstood and avoided, this disfigurement will notoccur in children or in adults.

540 Quintessence Infernalranal Volume 23, Number 8/1992

Esthetic Dentistry

References

1. Sande MA. Matidell GL: Antimierobial agents, in GilmanAG, Rail TW, Nies AS, et ill (eds): Goodman and Gilman's thePliarmocoiogical Basis of Therapeutics. New York, Per^amonPress, I99n,pp 1117-1121.

2. Wolfe ID, Reiclismistor J: Minoeyelinc hypcrpigmentation;skin, tooth, nail and bone involvement. Cmis 1%4;33:457^5K.

3. Poliak SC, DiGiovanna JJ, Gross EG, et al: Minocycline-associated tooth discoloration in young adults. J Am MedAasoc iy85;254(4):2930-2932.

4. Cale AE. Freedman PD, Lumerman H: Pigmentation of Ihejawbones and teeth secondary to minocydinc h yd roch I o ridetherapy. J Periodontoi I9S8;59:112-114,

.T. Rosen T, Hoffman TJ: Minocycline-inditced discoloration ofthe permanent teeth. J Am Acad Dermarol 1989:21:569

6. Ten Cale AR: Oral Histotogy. ed 3. St Lotiis, CV Mosby Co,lyS'». pp 1WI-1S3.

7. SkinnL'r CW. Niilbandian J: Tctrac-ydincs and mineralized tis-sues; review and perspectives, Yali'J Biot Med 1975;48:377-397.

8. Wallman IS, Hilton HB: Teeth pigmented by tetraeycline.Lancet 1952:1 :S27-S29.

9, Bevclander G, Rolle GK, Cohlaii SQ: The effect ot tlic ad-ministration of tetracycliiic on the development of leeth.} Dem fliv I%1;40:1U20-1024.

10. Atkinson HF. Hareourt JK: Tetracyclines in human dentine.Nature 1962; 19.^:508-509.

11. Davies AK, Cundall RB, Dandiker Y, et al: Photo-oxidationof teiraeyeline absorbed on liydrosyapatite in relation to thelight-induecd staining ot teeth, J Dent Res 1985;ö4:936-939.

12. Walton RE, O'Deli NL, Myers DL, et al: Esternal bleaeliingof tetracyciine stained teeth in dogs, y foí/oí/1982:8:536-542.

13. Aboü-Rass M: The elimination of tetiacycline diseolorationby intentional endodonties and internal bleaching. J Endodiy82;S:IOl.

14. Walton RE, O'Dcll NL, Lake ET, et al: Internal bleaching oftetracyclinc stained teeth in dogs. J Endod 1983:9:416-420.

15. Lake FT, O^Dell NL, Walton RE: The effect of internalbleaching in dentin. 7 £jii/od 1985;11:I41.

Ifi. Lin LC, Pitts DL, Burgess LW: An investigation into thefeasibility of photobleaching tetracyclinc stained teeth.7 Endod 1988:14:293-299, D

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Quintessence International Volume 23, Number 8/1992 541