Discussion - References.
Root-canal treatment of fused or geminated teeth has been described by various authors (Tagger 1975, Libfeld et al. 1986, Wong 1991). A literature review failed to reveal treatment of a trifid crown permanent maxillary first premolar. Although more than one separate rootcanal lends support to the diagnosis of fusion, the diagnosis of gemination was based on the clinical examination and finding that three of the canals joined to form a common main canal. The formation of this tooth within the normal complement of teeth and the similar mirror-image effect of the three crowns supports this diagnosis. Gemination occurs because of a partial division of a single tooth bud through invagination, resulting in completely or incompletely separated crowns (Pindborg 1970). In this case, the aetiology of this abnormal tooth development is unknown. Consultation with the family members and the referring dentist revealed no hereditary or causal link.
The tooth exhibited percussion and thermal sensitivity in addition to pain on palpation, symptoms indicative of an irreversibly inflamed pulp with extension of inflammatory changes to the periapex. As the tooth was caries-free and no history of trauma was reported, it is likely that the unusual anatomy lead to the irreversible condition of the tooth and the patients symptoms. Though not detected clinically, enamel deficiencies may be present in the developmental grooves between the three crowns. This would allow bacteria to gain access to the pulp chamber in a similar manner to that which occurs in dens invaginatus.
Management of the case required careful consideration of the possible morphological aberrations. Clinical and radiographic evaluation indicated that access into each of the crowns was necessary. The complexities of the root-canal systems could then be addressed during treatment. This case illustrates that, despite the unusual morphology and the lack of a comparative case in the literature, the use of sound endodontic principles resulted in successful treatment.
Blaney TD, Hartwell GR, Bellizzi R (1982) Endodontic management of a fused tooth: a case report. Journal of Endodontics 8, 227-30.
Brook AH, Winter GB (1970) A retrospective study of 'geminated' and 'fused' teeth in children. British Dental Journal 129, 123-30.
Clayton JM (1956) Congenital dental anomalies occurring in 3557 children. Journal of Dentistry in Children 23, 206-8.
Itkin AB, Barr GS (1975) Comprehensive management of the double root: report of case. Journal of the American Dental Association 90, 1269-72.
Libfeld H, Stabholz A, Friedman S (1986) Endodontic therapy of bilaterally geminated permanent maxillary central incisors. Journal of Endodontics 12, 214-6.
Pindborg JJ (1970) Pathology of the Dental Hard Tissues. Philadelphia, PA. USA: W.B. Saunders Co., pp. 51-3.
Shafer WG, Hine MK, Levy BM (1983) A Textbook of Oral Pathology, 4th edn. Philadelphia, PA, USA: W.B. Saunders Co., pp. 41-2.
Spatafore CM (1992) Endodontic treatment of fused teeth. Journal of Endodontics 18, 628-31.
Stabholz A, Friedman S (1983) Endodontic therapy of an unusual maxillary permanent first molar. Journal of Endodontics 9, 293-5.
Tagger M (1975) Tooth gemination treated by endodontic therapy. Journal of Endodontics 1, 181-4.
Tannenbaum KA, Alling EE (1963) Anomalous tooth development: case report of gemination and twinning. Oral Surgery 16, 883-7.
Wong M (1991) Treatment considerations in a geminated maxillary lateral incisor. Journal of Endodontics 17, 179-81.