A mesiodens is a supernumerary tooth that develops in the midline of the maxilla, typically positioned between the two central incisors. It often remains unerupted and hidden beneath the gum line or bone. Since it is not visible during a routine dental check-up, X-rays are the definitive tool for diagnosis, revealing its precise location and shape before it causes complications.
Visual Characteristics on X-ray Images
A mesiodens appears on an X-ray as a dense, bright white shadow (radio-opacity), composed of hard dental tissues like enamel and dentin, identical to a normal tooth. This density contrasts sharply with the surrounding gray or dark areas of the jawbone and soft tissues. The tooth’s morphology, or shape, is a primary feature seen on the radiograph. The most common form is conical, which looks like a small, simple peg or cone.
Less frequently, a mesiodens may present as a tuberculate shape, which has a complex crown with multiple cusps, or as a supplemental shape, which closely mimics a normal central incisor. The radiograph also defines the tooth’s orientation relative to the other teeth. While many mesiodentes are positioned vertically, a significant number are found in an inverted position, where the crown points upward toward the nasal cavity.
This inverted position is notable because the crown may appear near the roots of the permanent central incisors or high up in the palate. Radiographs confirm that most mesiodentes remain impacted, meaning they are fully embedded within the bone and fail to erupt. The exact location and angle determined from the X-ray dictate the potential for interference with developing permanent teeth.
Imaging Techniques Used for Detection
The detection of a mesiodens relies on various radiographic techniques, each providing a different perspective of the anterior maxilla. A periapical (PA) radiograph offers a detailed, close-up view of the central incisor area, excellent for assessing the relationship between the mesiodens and the roots of adjacent teeth. The panoramic radiograph captures a broader two-dimensional image of the entire jaw structure, providing a general overview of the mesiodens’ location within the dental arch.
However, both of these two-dimensional (2D) images have limitations in precisely determining the depth of the mesiodens—whether it is closer to the tongue (palatal) or the lip (buccal). Cone-Beam Computed Tomography (CBCT) addresses this limitation by producing a three-dimensional (3D) reconstruction of the area. The CBCT scan is valuable for complex or inverted mesiodentes, allowing for an exact determination of the tooth’s shape, orientation, and spatial relationship to adjacent structures like the nasal floor and the roots of permanent teeth, which aids surgical planning.
Consequences for Neighboring Teeth
The presence of a mesiodens can lead to several complications for the normal development and alignment of the surrounding permanent teeth.
- Delayed eruption or blockage of the permanent central incisors, where the mesiodens physically obstructs the natural eruption path. This obstruction can cause permanent teeth to become impacted or erupt improperly, leading to displacement or rotation.
- Tipping or shifting of adjacent incisors, resulting in a noticeable gap (diastema) between the two front teeth.
- Root resorption, where pressure or contact from the mesiodens causes the dissolution of the root structure of neighboring permanent teeth.
- Formation of a dentigerous cyst, a fluid-filled sac that develops around the crown of an unerupted tooth, which can grow and displace jawbone.
Treatment and Monitoring Protocols
Once a mesiodens is identified on an X-ray, the approach is surgical extraction. The decision to remove the mesiodens is based on the risk of complications it poses to the developing permanent teeth, such as confirmed blockage or displacement. Early intervention, often during the mixed dentition phase, is recommended to allow the permanent central incisors the best chance to erupt spontaneously into the correct position after the obstacle is removed.
Extraction may be timed to occur when the roots of the adjacent permanent teeth are nearing completion (around eight to ten years of age) to minimize the risk of damage during surgery. Following removal, careful monitoring ensures the permanent incisors begin to erupt normally. If eruption does not occur within the expected timeframe (six months up to three years), further treatment, such as surgical exposure and orthodontic mechanics, may be needed to guide the tooth into the dental arch.