**3.1 Gemination**

Gemination is an aberration that develops when a single tooth germ tries to divide by invaginating, which results in the partial creation of two teeth. The tooth typically has one or two crowns, which may be totally or partially separated, but only one root and one root canal [1].

Clinically, a single root has a bifid crown with complete segregation or minor grooving between two big crowns. The total number of teeth stays the same during gemination because only a single tooth bud can be partially split to change the number of teeth. The most often impacted teeth in both dentitions are the incisors and canines.

These are common pulp canals and either a single or partially divided pulp chamber, according to radiology, which are greater than usual crown width with a shallow groove (**Figure 2**).

## **3.2 Fusion**

Fusion is the joining of two distinct tooth germs, which can be seen radiographically as two different pulp chambers and root canals [2]. The action of pressure or mechanical physical force that produces close contact between two erupting teeth

**Figure 2.** *Features of gemination.*

**Figure 3.** *Courtesy: JSS Dental College, figure showing fusion of lateral incisor with supernumerary tooth.*

was identified as a possible explanation, although the exact cause of fusion is still unknown. It occurs more frequently in teeth at the front. In contrast to permanent teeth, it occurs more frequently in deciduous teeth [3].

Clinical: With or without a bifid crown, the tooth is about twice as large as it should be. Root canals in a tooth may be single or combined. Fusion may happen between a normal and a supernumerary tooth or result in fewer teeth [3, 4]. The union's true character and scope will become increasingly clear (**Figure 3**).

#### **3.3 Concrescence**

Concrescence is two fully formed teeth, joined along the root surfaces by cementum. The process is noted more frequently in the posterior and maxillary regions. Lack of adequate space and crowding of teeth are the most accepted elucidated aetiology.

Diagnosis is made commonly with the help of radiographs. It is not always possible to distinguish among concrescence, teeth in close contact and superimposed teeth. Radiograph will show union of two teeth with the help of cementum.

#### **3.4 Talon's Cusp**

The talon cusp, an aberrant structure that resembles an eagle's talon, is produced by the cingulum regions of a maxillary or mandibular permanent incisor [4], commonly observed on the lateral or central maxillary incisor.

Clinical: A T-shaped elevation on the tooth makes Talon's cusp an easy diagnosis.

Radiological: Where it occurs, overlaid on the incisors, there is a coating of enamel that appears to be normal, and the outline is smooth.

#### **3.5 Dilaceration**

The term 'dilaceration' refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth.

Clinical diagnosis is not possible.

Radiological: Curve or bending occurs anywhere along the length of tooth, sometimes at cervical portion or midway along the root or even just at the apex of root.

#### **Figure 4.**

*Clinical and intra-oral radiographic presentation of the condition. Courtesy. JSS Dental College.*
