Dens invaginatus (DI) or dens in dente is a developmental malformation resulting from the invagination of the enamel organ into the dental papilla before tissue calcification (Capar et al., 2015; Rozylo et al., 2018; Alkadi et al., 2021; Chen et al., 2021; Mabrouk et al., 2021; Hegde et al., 2022; Siqueira et al., 2022; Varun et al., 2022), whose etiology can be attributed to external factors during the development of the tooth germ, such as trauma, genetics, infection, and acceleration or retardation of growth in the bud stage (Hülsmann, 1997, Kirzioğlu and Ceyhan, 2009, Alkadi et al., 2021). The prevalence of DI ranges from 0.39 % to 13.5 % (Capar et al., 2015; Rozylo et al., 2018; Alkadi et al., 2021; Chen et al., 2021; Mabrouk et al., 2021; Hegde et al., 2022; Siqueira et al., 2022; Varun et al., 2022), with the upper lateral incisors being the most affected teeth, followed by the upper central incisors, canines, and upper premolars (Kirzioğlu and Ceyhan, 2009, Capar et al., 2015; Hegde et al., 2022).

Clinically, affected teeth may have a normal dental crown, but in most cases when the invagination is extensive, the crown may be atypical, with a barrel-shaped conical morphology, dilated with a bifid cingulum (Siqueira et al., 2022), or with a blind foramen on the palatal/occlusal surface (Zhu et al., 2017). Furthermore, the degree of anatomical complexity, which includes root canal anomalies, proximity to the pulp chamber, and incomplete rhizogenesis, makes the affected teeth more prone to develop carious lesions, pulpal pathology, and apical periodontitis (Nosrat & Schneider, 2015; Hegde et al., 2022).

The most widely used morphologic classification for DI was described by Oehlers in (1957) and uses two-dimensional radiographic images to categorize the vertical extent of DI into three types: Type I - the invagination is limited to the tooth crown; Type II - the invagination extends apically the root and ends in a "blind sac"; Type IIIa - the invagination goes beyond the cementoenamel junction and communicates laterally with the periodontal ligament through a pseudo-foramen; and Type IIIb - the invagination extends apically the root and communicates with the periodontal ligament through the apical foramen.

One of the limitations of this classification consists of the use of radiographic images (Siqueira et al., 2022), which are two-dimensional images and suffer from the superimposition of structures (Capar et al., 2015). Conversely, high-resolution cone beam computed tomography (CBCT) allows the evaluation of the DI by means of volumetric images, which provide details of the apex features (Capar et al., 2015, Alkadi et al., 2021), presence and dimensions of periapical lesions (Capar et al., 2015, Alkadi et al., 2021, Chen et al., 2021, Mabrouk et al., 2021, Alves Dos Santos et al., 2022; Hegde et al., 2022; Varun et al., 2022) type and the extent of invagination (Hegde et al., 2022; Siqueira et al., 2022), and relationship with the root canal, which favors treatment planning (Capar et al., 2015; Rozylo et al., 2018; Alkadi et al., 2021; Chen et al., 2021; Mabrouk et al., 2021). The invagination in DI may present as a pouch-like image with hypodense or hyperdense borders within the crown (enamel lining in the invagination) and/or extended to the root (Gallacher et al., 2016).

The extent of invagination of DI, especially in type III, is directly proportional to the anatomical complexity (Chen et al., 2021, Kalogeropoulos et al., 2022), and, thus, CBCT can be an indispensable tool in the diagnosis of DI (Alkadi et al., 2021), providing detailed information of the dental anatomy of complex DI with respect to the different levels of invagination (Alani & Bishop, 2008). Considering that the friable enamel of teeth with DI is more susceptible to pulpal infection by dehiscence, endodontic treatment planning based on limited information of the anatomy may negatively influence in deviation of the root canal trajectory (Alani & Bishop, 2008). Thus, CBCT can direct the clinician to an appropriate diagnosis and treatment plan (Kalogeropoulos et al., 2022) and thereby facilitate access to irregular and invaginated canals, measurement of the working length, cleaning, and shaping (Lee et al., 2020, Mabrouk et al., 2021). Because DI is frequently associated with endodontic and/or periradicular diseases, the aim of this systematic review and meta-analysis was to evaluate the prevalence and morphological characteristics of dens invaginatus using CBCT.