Cirujano Dentista

International Endodontic Journal (1997) 30, 79–90

REVIEW

Dens invaginatus: aetiology, classification, prevalence, diagnosis, and treatment considerations
M. HÜLSMANN
Department of Operative Dentistry, Zentrum ZMK, University of Göttingen, Göttingen, Germany

Summary
Dens invaginatus is a malformation of teeth probably resulting from an infolding of the dental papilla during toothdevelopment. Affected teeth show a deep infolding of enamel and dentine starting from the foramen coecum or even the tip of the cusps and which may extend deep into the root. Teeth most affected are maxillary lateral incisors and bilateral occurrence is not uncommon. The malformation shows a broad spectrum of morphologic variations and frequently results in early pulp necrosis. Root canal therapy maypresent severe problems because of the complex anatomy of the teeth. Aetiology, prevalence, classification, and therapeutic considerations including root canal therapy, apical surgery and prevention of pulpal involvement are reviewed. Keywords: dens invaginatus, endodontic treatment.

Introduction
Dens invaginatus (Fig. 1a–c) is a rare malformation of teeth, showing a broad spectrum ofmorphological variations. The affected teeth radiographically show an infolding of enamel and dentine which may extend deep into the pulp cavity and into the root and sometimes even reach the root apex (Fig. 2a–c). Tooth crowns as well as roots may exhibit variations in size and form. This kind of tooth malformation was described first by Ploquet in 1794 (Schaefer 1955), who discovered this anomaly in awhale’s tooth (Westphal 1965). Dens invaginatus in a human tooth was first described

Correspondence: Dr Michael Hülsmann, Department of Operative Dentistry, Zentrum ZMK, University of Göttingen, Robert-Koch-Str. 40, D-37075 Göttingen, Germany.
© 1997 Blackwell Science Ltd

by a dentist named ‘Socrates’ in 1856 (Schulze 1970). In 1873 Mühlreiter reported on ‘anomalous cavities in human teeth’, Baumein 1874 and Busch in 1897 published on this malformation. In 1887 Tomes described the dens invaginatus in his textbook A System of Dental Surgery, as follows: ‘The enamel investing the crown may be, and often is, perfectly well-developed; but we shall find at some point a slight depression, in the centre of which is a small dark spot. If the tooth be divided through its long axis, we shall find thatthe dark centre of the depression is in fact the choked-up orifice of a cavity situated within the substance of the tooth, external, however, and perfectly unconnected with the pulp-cavity. If the section be a fortunate one, we shall be able to trace the enamel as it is continued from the exterior of the tooth through the orifice into the cavity, the surface of which is lined more or lesscompletely with this tissue’ (Tomes 1887). From the 1920s to the 1950s numerous reports on cases of dens invaginatus malformation were published in the dental literature (Miller 1901, Lejeune & Wustrow 1920, De Jonge Cohen 1925, Kronfeld 1934, Rebel & Rohmann 1934, Hammer 1935, Kitchin 1935, Hoepfel 1936, Fischer 1936, Beust & Freericks 1936, Rushton 1937, Euler 1939, Swanson & McCarthy 1947, Zilkens &Schneider-Zilkens 1948, Egli 1949, Gustafson & Sundberg 1950, Bruszt 1950, Munro 1952, Schaefer 1953, Hitchin & McHugh 1954, Logar 1955, Künzel 1956, Petz 1956, Davidoff & Anastassowa 1956, Brabant & Klees 1956). Until 1959 more than 200 papers, mainly case reports, had been published on the dens invaginatus malformation (Grahnen et al. 1959). Dens invaginatus malformation again has been a subject ofinterest in recent years (Wells & Meyer 1993, Piattelli & Trisi 1993, Szajkis & Kaufman 1993, Pecora et al. 1993, Altinbulak & Ergül 1993, Skoner & Wallace 1994, Mangani & Ruddle 1994, Benenati 1994, Hülsmann & Radlanski 1994, Hülsmann 1995a,b, 79

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M. Hülsmann

Fig. 1 (a) SEM; (b) microscopic and (c) radiographic appearance of a dental invagination. The invagination is completely...