I am starting a new series of posts on anatomy on radiographs. There will be two posts on intraoral radiographs (Part I – anterior and Part II – posterior), one on occlusal radiographs, one on pantomographs and lastly one on skull radiographs (primarily lateral cephalometric skull radiographs).
Anatomical radiographic appearances
Foramina – round to ovoid radiolucent entities, may or may not have a radiopaque/corticated edge.
Canals – radiolucent line or band, may or may not have radiopaque/corticated edge(s).
Now on to the anterior portion of intraoral radiographs.
The mandible is a nice place to start as there are fewer anatomical landmarks identifiable in the anterior region (compared to the maxilla). There are four anatomical landmarks frequently identifiable: lingual foramen, nutrient canals, mental ridge, and inferior border of the mandible.
The lingual foramen appears as a small radiolucent circle directly inferior to the central incisors. It is not always visible on every patient.
Nutrient canals (vascular canals) are canals containing blood vessels coursing throughout the maxilla and mandible. They are very small and more commonly seen in areas of thin bone (hence the anterior mandible). They appear as a radiolucent line or band coursing in a vertical direction.
The mental ridge (mental triangle) appears as two oblique thick radiopaque bands that that meet in the midline giving it the appearance of an inverted V or triangle shape. This is more commonly seen when an increased negative vertical angle is used.
The inferior border of the mandible appears as a thick radiopaque band.
The maxilla has quite a bit more anatomy evident including a good portion of the nasal cavity.
The intermaxillary suture appears as a thin radiolucent line between the two maxillary central incisors. It may not be visible on all patients.
The incisive foramen appears as a round to ovoid radiolucent area between the roots of the maxillary central incisors.
The anterior nasal spine appears as an inverted radiopaque triangle or V-shaped. It is on the midline and superior to the apices of the maxillary central incisors.
The incisive fossa appears as a well-localized radiolucent area around the root of the maxillary lateral incisor. This is due to a decrease in bone thickness in this region.
The soft tissue of the nose appears as a radiopaque area superimposed over the maxillary anterior teeth. The tip of the nose is seen over the maxillary central incisors. The ala of the nose is seen over the lateral incisors.
The floor of the nasal cavity appears as a thin straight radiopaque line.
The nasal cavity appears as a radiolucent area superior to the floor of the nasal cavity.
The nasal septum appears as a radiopaque band going superior from the floor of the nasal cavity. It is on the midline.
The inferior nasal concha appears as a round to ovoid radiopaque mass superior to the floor of the nasal cavity.
The Y line of Ennis (inverted Y) is not a true anatomical landmark but seen only on radiographs due to superimposition of the floor of the nasal cavity (straight radiopaque line) and the border of the maxillary sinus (curved radiopaque line).
The border of the maxillary sinus appears as a curved, thin radiopaque line superior to the roots of the canine and posterior teeth. The maxillary sinus appears as a radiolucent area superior to the border of the maxillary sinus.
I hope you find this first post on intraoral anatomy informative. If you have any questions, please let me know.