Browse the corpus

The process of development of teeth is a very complex process resulting from interactions between the ectoderm of the oral cavity, which gives rise to cells that produce enamel, and the neural crest ectomesenchyme which gives rise to the tooth structures other than enamel. At first, i.e., during the six weeks of intrauterine life, the tooth germ starts growing, and the cells forming the mineralized portion start differentiating. Thereafter, dentin and enamel matrices are laid down by these cells, which later start mineralizing. As the completed tooth erupts into the oral cavity, components of the periodontium, which includes periodontal ligament, cementum, and alveolar bone, start surrounding the root.

Any disturbance during the development of the tooth, such as disturbance in the interaction between epithelium and the mesenchyme may lead to anomaly related to number, shape, size, contour, or form. The type of anomaly depends upon the developmental stage affected. Various local and systemic factors such as local trauma, radiation damage, any nutritional deficiency, congenital disease, hormonal influences, or inflammatory process may give rise to these anomalies. The various developmental anomalies include: Hypodontia: It is a disorder characterized by a lack of one or a few teeth and is more frequently observed in permanent teeth, particularly premolars and incisors. Oligodontia: It refers to the development of fewer than the normal number of teeth. Anodontia: It refers to the absence of all the teeth and may affect both primary and permanent teeth. This condition is extremely rare. Hyperdontia: Is characterized by an increased number of teeth than the regular number of supernumerary teeth. They can occur in primary or permanent dentition. They most commonly occur in the maxillary anterior region between the incisors, in which case they are termed mesiodens. It may also occur distal to the third molar in maxilla or mandible. Gemination: It is the condition that arises when two teeth develop from the same follicle and attempt to divide, resulting in a single tooth with two incompletely separated crowns or one incompletely separated crown but with a single root and root canal. It is sometimes also referred to as double teeth or dental twinning and is more commonly associated with the maxillary anterior region.[9][10] Fusion: It is the condition where two teeth develop from two different dental follicles, but during the process of formation, they fuse partially or completely, resulting in a single large tooth or tooth fused completely at crown or root only. The degree of fusion depends on the stage of tooth formation at which fusion occurs. When fusion begins before the calcification stage, complete union occurs, and when it occurs at a late stage, incomplete union occurs. It is more common in the anterior region of the deciduous dentition.[11]

Fusion: It is the condition where two teeth develop from two different dental follicles, but during the process of formation, they fuse partially or completely, resulting in a single large tooth or tooth fused completely at crown or root only. The degree of fusion depends on the stage of tooth formation at which fusion occurs. When fusion begins before the calcification stage, complete union occurs, and when it occurs at a late stage, incomplete union occurs. It is more common in the anterior region of the deciduous dentition.[11] Concrescence: It is the fusion of two teeth at the cementum region only. It may occur either during root formation termed as true/developmental concrescence or after the completion of root formation termed as acquired/inflammatory concrescence. Unlike fusion, concrescence commonly occurs in the posterior region of the maxilla. The union of cementum may vary in degree from one small site to the involvement of the entire root surface.[12] Dilaceration: It is a bend in the root of the tooth in any direction or deviation from the linear relationship of the crown to its root. The site of bending varies with the position of the tooth affected. In the anterior teeth, the bend presents in the apical third of the tooth, middle third in maxillary first molars, and coronal third in the third molars. Permanent teeth are commonly affected. Dens invaginatus: It is also referred to as dens in dente or extensive compound odontoma or pregnant women anomaly and is characterized by invagination on the external surface of the tooth crown. It occurs before the calcification begins. The degree of invagination may vary from a short pit in the crown region to a deep invagination extending into the root portion or, in rare cases, even beyond the apex. A maxillary lateral incisor is the most commonly affected tooth. It can be easily identified on the radiograph by the pear-shaped invagination and narrow constriction at the opening.[13]

Dens invaginatus: It is also referred to as dens in dente or extensive compound odontoma or pregnant women anomaly and is characterized by invagination on the external surface of the tooth crown. It occurs before the calcification begins. The degree of invagination may vary from a short pit in the crown region to a deep invagination extending into the root portion or, in rare cases, even beyond the apex. A maxillary lateral incisor is the most commonly affected tooth. It can be easily identified on the radiograph by the pear-shaped invagination and narrow constriction at the opening.[13] Dens evaginatus: It refers to an accessory cusp in the form of a tubercle or elevation or protuberance. It is also known as Leong's premolar or evaginatus odontoma or occlusal pearl. It commonly occurs on the occlusal surface of a premolar.  It may also occur in the anterior region, in which case it is referred to as Talon's cusp. The syndromes commonly associated with this anomaly include Rubinstein-Taybi syndrome, Mohr syndrome, Sturge Weber syndrome, and Berardinelli Seip syndrome.[14] Taurodontism: It is also referred to as bull's teeth and is *characterized by teeth with abnormally large pulp chambers with furcation displaced apically, resulting in larger than normal apical-occlusal height. Molars are the most commonly affected teeth. It frequently correlates with syndromes such as Klinefelter's syndrome, Mohr syndrome, orofacial digital syndrome, and Down syndrome. Peg laterals: It is commonly seen in the maxillary anterior region affecting the maxillary lateral incisor and is characterized by a tooth that is conical in shape with a taper in the incisal region. Amelogenesis imperfecta: It is an inherited dental defect of the enamel characterized by abnormally soft and fragile enamel resulting in thin enamel, which can easily wear off or chip off, exposing the underlying dentin and causing yellow to brown discoloration. It affects both primary and permanent dentition.