PDF: Management of Type III Dens Invaginatus in a Mandibular Premolar

Dens invaginatus is a well-known malformation of teeth, which probably results from an invagination of enamel organ into dental papilla during tooth development.

The endodontic treatment of invaginated teeth may be challenging due to difficulties in accessing the root canals and also due to complex variations of internal morphology. This article presents the endodontic management and follow-up in a rare case of right mandibular second premolar with Oehlers' type III dens invaginatus.

The result of cold pulp testing was positive for this tooth but it was associated to a sinus tract and periapical lesion. Herein, it is described the root canal therapy of this tooth combined with periapical surgery, emphasizing the importance of proper diagnosis and planning by using cone beam computed tomography (CBCT). 

This case report presents the proper periapical healing 6 months after the combination of nonsurgical and surgical treatments. It also shows that CBCT is an important auxiliary examination to avoid errors in diagnosis and subsequent treatment of dental anomalies.

Dens invaginatus (DI), also known as ‘dens in dente’, is a dental anomaly marked as an early invagination of enamel and dentine that may extend deep into the pulp cavity and to the roots, sometimes reaching the apex.

The reported prevalence of permanent teeth affected with DI is variable, ranging from 0.3% to 10%, due to methodological differences in the cohorts studies, identification criteria used and diagnostic difficulties. The most commonly affected tooth is the maxillary lateral incisor. 

This condition may coexist with other anomalies, such as talon cusps. DI rarely occurs in mandibular posterior teeth, extending from the occlusal pit. Few cases have been reported in mandibular premolars.


The degree of malformation associated with DI has been classified by Oehlers into three categories and this classification system is the most used worldwide. Type I represents a minor invagination, lined by enamel, not extending beyond the cementum-enamel junction. 

In Type II, the enamel-lined anomaly invades the root but remains as a blind sac; it may communicate or not with the dental pulp. In Type III, the invagination penetrates through the root, reaching the apical area and a second foramen emerges in the periodontium.