External root resorption after bleaching: A case report Saad Al-Nazhan, COLLEGE

MSD, BDS,n Riyadh,

OF DENTISTRY,

UNIVERSITY

Saudi Arabia

OF KING

An external root resorption occurred after bleaching female dental assistant. The resorption was noticed history of trauma. An attempt to stop the resorption corrected surgically with amalgam. (ORAL SURG ORAL MED ORAL PATHOL 1991;72:607-9)

SAUD and was diagnosed radiographically in a 26-year-old 6 months after bleaching. The involved tooth had no by using calcium hydroxide failed. The perforation was

B

leaching is a simple esthetic technique used on discolored anterior teeth. This procedure is usually preferred to full-coverage restoration. The common bleaching methods are either by placing 30% hydrogen peroxide (Superoxol) and sodium perborate in the pulp chamber and sealing it (walking technique) or by activating the Hz02 by heat (thermocatalytic tech-

nique).lm3 Good results can be obtained with either method. External cervical root resorption after bleaching has been reported by many investigators.4-10 All the reported cases suggest a causal relationship between bleaching and external cervical root resorption. This article reports a case where an external root resorption was noticed 6 months after bleaching. In addition, an attempt to explain this postbleaching resorption phenomenon is discussed. CASE

REPORT

In 1983 a 22-year-old female dental assistant was seen by a general dentist to restore a Class III cavity of the left maxillary central incisor. The cavity was filled with composite resin. After a year the tooth became symptomatic. Irreversible pulpitis was diagnosed, and root canal therapy was done (Fig. 1). A few days later the tooth showed discoloration. In 1988 the tooth became symptomatic again and the patient decided to see an endodontist. Retreatment was done (Fig. 2), and the tooth was bleached with the thermocatalytic and walking bleach techniques. The bleach-

Fig. 1. Preoperative radiograph of left maxillary central incisor before retreatment. Root canal therapy was done in

aLecturer, Department of Restorative Dentistry, Division of Endodontics.

1983.Radiolucentarea could be seenat distal surfaceof root {arrow),which couldbeinterpretedasearly signof root resorption.Note horizontal bonelossbetweencentral and

7/15/28823

lateral aspects. 607

608

Al-Nazhan

ORAL

SURC

ORAL

MED

ORAL

PATHOL

November 199

Fig. 2. Prebleachingradiograph(1988) showingretreatment of root canal. Radiolucentarea at distal sideof root surface(arrow) is sameafter 4 years.Thereis nochangein levelof horizontal bonelossbetweencentral andlateral aspects.

ing procedurewasdonefive timesoncea weekuntil the discoloration disappeared.A follow-up radiograph taken 6 monthslater showedexternal root resorption(Fig. 3). Part of the gutta-percha was removedand calcium hydroxide wasplacedin the pulp chamberfor 2 months.The patient wasreferred to the endodonticdepartmentat King Saud University for follow-up becauseher endodontisthad to leavethe country. A radiographwastaken, which showed severeexternal root resorptionat the bottom of a periodontal pocketmorethan 10 mm deep.The patient had no history of trauma before or after the bleachingprocedure. Surgery wasperformedto obliterate the perforation (Fig. 4). The patientwasscheduledfor follow-upevery6 months. DISCUSSION

The etiology of discolored teeth and clinical evaluation of bleached teeth were discussedby Brown,” but no attention was given to specific radiographic examination in his study. Several hypotheses have beenpresentedto explain why external root resorption

I

Fig. 3. Radiograph6 monthsafter bleaching.External root resorptionhad occurredat distalsurfaceof root of left maxillary central incisor.

occurs after bleaching. 4-‘o Becausethe dentin structure has been proven to be permeable to different solutions12 and the permeability increases with acidetching, the useof strong bleaching agent such as 30% Hz02 can penetrate the dentin through the dentinal tubules. This allows the Hz02 to irritate the periodontal ligament and surrounding tissue and causes inflammatory resorption. In addition, Pashley and Livingston ** found that an increase in temperature can induce movement of any liquid in the dentinal tubules. A third explanation not applicable to this caseis the gap between cementum and enamel, which appearsin 10% of the population as mentioned in Orban’s textbook.13 This uncovered dentin in the cervical area may allow the bleaching agent to leak into the periodontal ligament and the surrounding tissue and causeresorption. Theoretically, deep scaling and root planing may cause a similar situation further down the root. Another possibility is the presenceof lateral or accessory canals and radiographically undetected horizontal or vertical fracture at the middle or cervi-

External root resorption after bleaching

Volume 72 Number 5

609

stein.‘O Radiographic and clinical follow-up examinations of bleached teeth are important to detect early changes. It is important to prevent discoloration of teeth by proper cleaning of the pulp chamber during access cavity preparation and after obturation. Finally, the level of the removed root canal filling material and the placement of a protective base should be considered.5, 9 This might help in preventing or reducing the development of external root resorption after bleaching. REFERENCES

Nutting E, Poe G. A new combination of bleaching teeth. J South Calif Dent Assoc1963;31:289-91. 2. Boksman L, Jordan R, Skinner D. A conservative bleaching treatment for the nonvital discolored tooth. Compend Cont Educ Dent 1984;5:471-578. 3. Freccia W, Peters D, Lorton L, Bernier W. An in vitro comparison of nonvital techniques in the discolored tooth. J Endod 1.

1982;8:70-7.

Fig. 4. Treatment of resorption with amalgamfilling. Amalgam waspolishedbefore flap wassutured.

cal third of the tooth root, which may act as a channel for the bleaching agent. Hz02 rapidly liberates oxygen when it comes in contact with blood and tissue proteins and can cause tissue emphysema. 14,l5 According to the Poisindex,‘6 Hz02 concentration exceeding 10% is toxic and irritating, causing burns when in contact with tissue. In addition, 30% Hz02 solution has been reported to increase the mitotic activity of human oral epithelium.17 Becausethe acidic environment of the root surface

may cause a denaturing of the dentin and initiate an inflammatory resorption,5 Ca(OH)z (pH 12.5) has

been tried after bleaching to neutralize the acidic environment and to stop the resorption.6 In the present case Ca( OH)2 was tried, but unfortunately the defect was too extensive and the Ca(OH)2 was washed away by saliva because of the deep periodontal pocket. In conclusion, 30% Hz02 is a strong bleaching agent and should be used with caution as concluded by Cvek and Lindval17 and by Friedman and Rot-

4. Harrington G, Natkin E. External resorption associated with bleaching of pulpless teeth. J Endod 1979;5:344-8. 5. Lado E, Stanley H, Weisman M. Cervical resorption in bleached teeth. ORAL SURC ORAL MED ORAL PATHOL 1983: 55:78-80. 6. Montgomery S. External cervical resorption after bleaching a nululess tooth. ORAL SURG ORAL MED ORAL PATHOL 1984: 57:203-6. 7. Cvek M. Lindvall A-M. External root resorption following bleaching of pulpless teeth with oxygen peroxide. Endod Dent Traumatol 1985;1:56-60. 8. Latcham N. Postbleaching cervical resorption. J Endod 1986: 121262-5. 9. Goon W, Cohen S, Borer R. External cervical root resorption following bleaching. J Endod 1986:12:414-S. 10. Friedman S, Rotstein I, Libfeld H,‘Stabholz A, Heling I. Incidence of external root resorption and esthetic results in 58 bleached pulpless teeth. Endod Dent Traumatol 1988;4:23-6. 11. Brown G. Factors influencing successful bleaching of the discolored root-filled tooth. ORAL SURG ORAL MED ORAL PATHOL 1965;20:238-44. 12. Pashley D, Livingston M. Effect of molecular size on permeability coefficients in human dentine. Arch Oral Biol 1978; 23:391-5. 13. Bhaskar SN, ed. Orban’s oral histology and embryology. 8th ed. St Louis: CV Mosby, 1976:195. 14. Bhat K. Tissue emphysema caused by hydrogen peroxide. ORAL SURG ORAL MED ORAL PATHOL 1974;38:304-7. 15. Kaufman A. Facial emphysema caused by hydrogen peroxide irrigation: report of case. .l Endod 1981;7:470-2. 16. Overview: hydrogen peroxide-an overview of diagnosis and treatment. Denver: Poisindex, 1988:1-2. 17. Gargiulo A, Wentz F, Orban B. Mitotic activity of human oral epithelium exposed to 30 per cent hydrogen peroxide. ORAL SURG ORAL MED ORAL PATHOL 1961;14:474-91. Reprint requests: Saad Al-Nazhan, MSD, BDS Department of Restorative Dentistry Division of Endodontics College of Dentistry University of King Saud P.O. Box 60169 Riyadh 11545, Saudi Arabia