The prevalence of DE is between 1 and 4 percent, and it occurs most commonly in people in the Mongoloid racial group, which includes the Paleo-Asiatics (Indians of North, Central and South America and Eskimos), the Neo-Asiatics (Chinese, Thais and Japanese) and the Indonesian-Malays (Filipinos).^1,2 DE also has been observed in Chinese, Thai and Caucasian people.² It most commonly is observed in premolars but may occur in molars, canines and incisors,² and it occurs in the mandible five times more frequently than in the maxilla.¹

Since the tubercle usually occurs bilaterally and on the lingual surface of the buccal cusp or in the center of the occlusal surface, it can be worn easily or fractured, resulting in pulpal exposure, pulpal infection, loss of vitality, facial infection and osteomyelitis.^3,4 In a study of 2,373 Chinese, Malays and Indians, Yip⁴ observed 57 premolars exhibiting DE. Eighty-two percent of the teeth exhibiting DE had worn or fractured, and 26.3 percent exhibited pulpal involvement.

Another dental anomaly is the talon cusp, which occurs as an accessory cusp on the lingual surface of either permanent or primary incisors and projects from the cingulum area of the tooth. The talon cusp is similar to DE in that it is composed of enamel, dentin and pulp and is subject to pulpal exposure if the cusp is removed rapidly.⁵ The prevalence of the talon cusp is 0.17 to 7.7 percent. Uyeno and Lugo⁶ proposed that the talon cusp and DE are the same dental anomaly.

Many treatment options for DE have been reported in the literature, and they have changed over time. In 1949, Tratman⁷ noted that if a periapical infection occurred in a tooth exhibiting DE, in which the tubercle had fractured or was worn, the tooth was extracted since endodontic treatment was contraindicated because of the wide open apex and abnormal root patterns associated with DE. In 1967, Oehlers and colleagues⁸ advocated intermittent grinding of the tubercle to encourage reparative dentin formation, but this method was found to be unreliable. Yong⁹ successfully treated 39 asymptomatic and vital teeth by removing the tubercle and placing either a direct or indirect pulp cap followed by an amalgam restoration in 1974. Prophylactic pulp capping allowed for the continued development and closure of the root apex. In 1983, Bazan and Dawson¹⁰ suggested that a sealant be applied around the tubercle to prevent its fracture and to allow the occlusal forces to induce pulpal recession. They found, however, that an unfilled sealant did not prevent occlusal wear and instead suggested the use of a filled resin restoration. Hill and Bellis² noted in 1984 that this treatment could lead to more occlusal interferences around the larger tubercles. They suggested using direct or indirect pulp capping followed by a preventive resin restoration to eliminate this potential problem. In 1996, Sim¹¹ compared treatment of teeth with direct or indirect pulp capping followed by either amalgam or preventive resin restorations. He found that 0.52 percent of the teeth restored with preventive resin restorations and 5.37 percent of the teeth restored with amalgam restorations developed pulpal signs and symptoms.

In a 1991 article on diagnostic and treatment challenges associated with DE, Ju³ proposed the following protocol for pulpal management:

– A partial vital pulpotomy with calcium hydroxide should be used for asymptomatic teeth with immature root formation, as the calcium hydroxide encourages further dentinogenesis.

– A pulpectomy should be used for asymptomatic teeth with mature roots.

– Apexification with calcium hydroxide followed by conventional endodontic therapy should be used to manage symptomatic vital or nonvital immature teeth.

– If apexification or pulpectomy measures fail, a root-end resection and a root-end amalgam restoration may be necessary.

Extraction may be necessary if the root is short and the apex is wide open or if apical root resorption is funnel-shaped.^2,9 Extraction also should be considered in cases in which there is crowding and the involved tooth would need to be extracted before orthodontic treatment or in instances in which an apexification procedure has failed or is contraindicated.⁶ Another instance in which extraction is indicated is in cases in which the DE tooth is a mesiodens, or supernumerary tooth.¹²

	CASE REPORT

TOP ABSTRACT CASE REPORT DISCUSSION CONCLUSIONS REFERENCES

 
We examined a 9-year-old Hispanic girl and found five erupted premolars (teeth nos. 4, 5, 12, 21 and 28) with evidence of DE (Figure 1 and Figure 2 were taken six weeks after the initial examination and three weeks after the extraction of tooth no. J). There was a strong suggestion of DE on tooth no. 13 and radiographic evidence of DE on teeth nos. 20 and 29. Teeth nos. 5 and 12 had occlusal caries where the tubercles had fractured off.

View larger version (108K): [in this window] [in a new window]   Figure 1. Photographic evidence of dens evaginatus on tooth no. 4 (A), intraoral appearance of occlusal caries on teeth nos. 5 and 12 at the site of fractured tubercle (B, C), and white halo on tooth no. 13 (D) in a patient age 9 years and 4 months.

View larger version (103K): [in this window] [in a new window]   Figure 2. Dens evaginatus presenting as an exaggerated enlargement of the transverse ridge on tooth no. 21 (A) and a slight enlargement of the transverse ridge on tooth no. 28 (B) in a patient age 9 years and 4 months.

A periapical radiograph of tooth no. 13 revealed an abnormal-appearing root that was both short and diffuse (Figure 3). At the sixth visit, the patient had a left facial cellulitis that extended to the orbit. We extracted tooth no. 13 and placed the patient on a regimen of penicillin.

View larger version (85K): [in this window] [in a new window]   Figure 3. Periapical radiograph of tooth no. 13 (arrow) revealing abnormal root development and periodontal defect on the mesial aspect in a patient aged 9 years and 4 months.

	DISCUSSION

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We made the decision to extract tooth no. 13 after considering several options. Generally, apexification is the treatment of choice for an immature tooth; however, the dentinal walls of an immature tooth with an open apex are thin and more susceptible to fracture. The dentinal walls of tooth no. 13 were narrow and poorly developed, and the process of apexification would have narrowed the dentinal walls further. The crown:root ratio also was unfavorable. Echeverri and colleagues¹ noted vertical root fractures in two premolars with DE in an 11-year-old Hispanic boy who had been treated by apexification. They suggested that the etiology of the fractures might have been related to the immature development of the root, which was unable to withstand the increased occlusal forces associated with a growing child.

We were not present when tooth no. J was extracted in the case we reported and were unable to observe whether tooth no. 13 initially had DE. Given that the patient’s other premolars exhibited DE, it is likely that tooth no. 13 also did. The lingual aspect of the facial cusp of tooth no. 13 contained a thin white halo in the area where the other premolars exhibited the DE. The periapical radiographs taken when the patient was 6 years and 11 months old revealed tubercles characteristic of DE in all of the unerupted premolars. Since the white halo was observed on the lingual surface of the facial cusp, it is possible that the DE fractured when tooth no. J was extracted or soon after eruption (Figure 4). Also, the history of pulpal necrosis in a noncarious tooth and the unusual root formation supports the fact that tooth no. 13 had DE.

View larger version (95K): [in this window] [in a new window]   Figure 4. The site of occlusal caries (A) on tooth no. 12 left after the tubercle fractured and the white halo (B) on tooth no. 13 representing the site of the fractured tubercle.

There was a large funnel-shaped resorptive defect at the periapex of tooth no. 13, which makes bacterial invasion a possible explanation and successful endodontic therapy doubtful or contraindicated. According to the literature, pulpal necrosis in noncarious DE teeth has been caused by a pulpal exposure and bacterial invasion through the enamel of the occlusal table into the pulp.^1,2,6,9–12 Although the pathology report in our case cited that there was no communication between the pulp and the oral cavity, this communication may have been lost during processing. Further evaluation of the histologic section of tooth no. 13 revealed acute inflammation and pulpal necrosis concentrated more in the coronal portion of the pulp than the other parts. Occurrence of anachoretic pulpitis is rare and has not been reported in humans. In our case, the occurrence of trauma was highly unlikely, since all of the permanent teeth might be more susceptible to pulpal necrosis caused by traumatic occlusion from a primary tooth.

	CONCLUSIONS

TOP ABSTRACT CASE REPORT DISCUSSION CONCLUSIONS REFERENCES

 
Because of DE’s frequent and early pulpal complications, it presents a challenge to the practitioner. In the case we reported, the unusual presentation of symptoms, as well as the radiographic and clinical appearance of tooth no. 13, resulted in both a difficult diagnosis and limited treatment options.

View larger version (90K): [in this window] [in a new window]   Dr. Stecker was a pediatric dental resident, University of Minnesota School of Dentistry, Minneapolis, at the time the patient was treated. She now is in private practice in St. Paul, Minn. Address reprint requests to Dr. Stecker at 4308 Arthur St. N.E., Columbia Heights, Minn. 55421, e-mail "stec0023{at}tc.umn.edu".

View larger version (104K): [in this window] [in a new window]   Dr. DiAngelis is chief of dentistry, Hennepin County Medical Center, Minneapolis, and a professor, University of Minnesota School of Dentistry, Minneapolis.