Nasal fossae – The nasal fossae (plural; singular - fossa) are the nasal openings located above the maxillary anterior teeth. The fossae are divided in the midline into right and left chambers. Radiographically, the nasal fossae appear as vertically oblong radiolucent structures bounded by bone. These structures can be seen on maxillary central incisor periapical views and partially on lateral incisor and canine periapicals.
Nasal septum – The nasal septum is a bony vertical band-like midline structure that divides the nasal cavity into right and left chambers. The nasal septum is a radiopaque landmark visible on maxillary central incisor periapicals.
Anterior nasal spine – The anterior nasal spine (ANS) is a bony projection located at the base of the nasal septum in the maxillary midline. Radiographically, the ANS appears as a V-shaped or triangular point radiopacity. This structure is recorded on maxillary central incisor periapicals.
Inferior nasal concha – The inferior nasal concha or turbinate bone projects into the inferior aspect of the nasal fossa from the lateral walls of the nasal cavity. These bilateral radiopaque structures (conchae) are sometimes visible on central and lateral incisor periapicals.
Mid-palatine suture – The mid-palatine suture is the interface of the two halves of the premaxilla where they come together in the midline. The mid-palatine suture is also referred to as the median palatal suture. It courses from the alveolar crest through the midline to the posterior aspect of the hard palate. This structure appears radiographically as a thin vertical linear radiolucency in the midline on maxillary central incisor periapicals.
Incisive foramen – The incisive or nasopalatine foramen is located in the midline on the lingual aspect of the hard palate above the central incisor teeth crowns. The foramen is the termination of the nasopalatine canal. Radiographically, it appears between the roots of the central incisor teeth as a round to oval radiolucency less than one centimeter in diameter. It has a range of sizes and shapes, so variation is not unusual. This structure is recorded on maxillary central incisor periapicals.
Lateral fossa – The lateral fossa is a slight dip or depression in the bone on the labial aspect of the maxilla near and around the lateral incisor tooth root. This diffuse radiolucency appears bilaterally and is recorded on lateral incisor and canine periapicals. It is sometimes referred to as the canine fossa.
Inverted Y – The inverted Y is a radiographic landmark that depicts where the nasal fossa crosses the maxillary sinus. The boundary between them is shaped like an upside-down letter Y, hence its name. The periapicals below demonstrate the inverted Y, a classic radiographic landmark of the right and left anterior maxilla. The fossa is positioned toward the midline while the sinus extends toward the posterior aspect of the maxilla. Typically, the inverted Y sits apical to the maxillary lateral incisor and canine teeth. No comparable structures are found in the mandibular lateral incisor and canine areas which differentiates maxillary from mandibular anterior periapicals.
Nasal soft tissue – The soft tissue of the nose, including the tip and ala (corner of the nose), often can be seen superimposed over the roots of the teeth on anterior periapicals. The nasal soft tissue appears radiopaque.