Intraoral Radiographic Anatomy The following slides identify the

Intraoral Radiographic Anatomy The following slides identify the anatomical structures that may be seen on intraoral films. These structures are more likely to be seen when using the bisecting angle technique because of the increased vertical angulation (increased positive in the maxilla and increased negative in the mandible) commonly used with this technique. Since some of the structures may be confused with pathology, it is important to understand their normal appearance in order to make a proper diagnosis.

Maxillary Incisor a b c d e f g a = nasal septum b = inferior concha c = nasal fossa d = anterior nasal spine e = incisive foramen f = median palatal suture g = soft tissue of nose

facial view c b a palatal view f e d a = nasal septum b = inferior concha c = nasal fossa d = anterior nasal spine e = incisive foramen f = median palatal suture

facial view Nasal septum

facial view a Inferior concha

facial view Nasal fossa

facial view Anterior nasal spine

palatal view Incisive foramen

palatal view Median palatal suture

Soft tissue of the nose

a a b d b e Red arrow points to periapical lesion (post-endo). Red arrows = lip line

d f g Red arrow = mesiodens (supernumerary tooth) Blue arrow = chronic periapical periodontitis. Tooth # 9 is non-vital (trauma) and needs endo.

Superior foramina of the nasopalatine canals (red arrows). These foramina lie in the floor of the nasal fossa. The nasopalatine canals travel downward to join in the incisive foramen.

a b d The red arrows point to an incisive canal cyst; the orange arrow identifies the root of tooth # 7. f All the incisors are non-vital and have periapical lesions. The purple arrows point to external resorption; the blue arrow identifies internal resorption.

The red arrows point to the soft tissue of the nose. The green arrows identify the lip line.

Maxillary Cuspid a b a = floor of nasal fossa c b = maxillary sinus c = lateral fossa d = nose d

facial view a a c c b b a = floor of nasal fossa b = maxillary sinus c = lateral fossa (a & b form inverted Y)

facial view Y Floor of nasal fossa (red arrows) and anterior border of maxillary sinus (blue arrows), forming the inverted (upside down) Y.

facial view Lateral fossa. The radiolucency results from a depression above and posterior to the lateral incisor. To help rule out pathology, look for an intact lamina dura surrounding the adjacent teeth.

Soft tissue of the nose Red arrows point to nasolabial fold. Also note the inverted Y.

The maxillary sinus surrounds the root of the canine, which may be misinterpreted as pathology. The white arrows indicate the floor of the nasal fossa. The maxillary sinus (red arrows) has pneumatized between the 2 nd premolar and first molar

The red arrow identifies the lateral fossa. The pink arrow points to CPP (chronic periapical periodontitis = abscess, granuloma, etc. ).

Maxillary Premolar b a c a = malar process b = sinus septum c = sinus recess d = maxillary sinus d

facial view b a c d b a c a = malar process b = sinus recess c = sinus septum d = maxillary sinus d

facial view Malar (zygomatic) process. U or j-shaped radiopacity, often superimposed over the roots of the molars, especially when using the bisecting-angle technique. The red arrows define the lower border of the zygomatic bone.

facial view Sinus septum. This septum is composed of folds of cortical bone that arise from the floor and walls of the maxillary sinus, extending several millimeters into the sinus. In rare cases, the septum completely divides the sinus into separate compartments.

facial view Sinus recess. Increased area of radiolucency caused by outpocketing (localized expansion) of sinus wall. If superimposed over roots, may mimic pathology.

facial view Maxillary Sinus. An air-filled cavity lined with mucous membrane. Communicates with nasal cavity through 3 -6 mm opening below middle concha. Red arrows point to neurovascular canal containing superior alveolar vessels and nerves.

Blue arrows identify radiopacity which is a mucous retention cyst. Note relatively recent premolar extraction sites. Green arrow points to neurovascular canal. The red arrows point to the nasolabial fold. The thicker cheek tissue makes the area more radiopaque posterior to the line.

Pneumatization. Expansion of sinus wall into surrounding bone, usually in areas where teeth have been lost prematurely. Increases with age.

Maxillary Molar e f a = maxillary tuberosity b = coronoid process d = pterygoid plates d c e = zygoma b c = hamular process f = maxillary sinus a

facial view e e g g d f c a b d c a b f a = maxillary tuberosity* e = zygoma (dotted lines) b = coronoid process f = maxillary sinus c = hamular process g = sinus recess d = pterygoid plates * image of impacted third molar superimposed

facial view Maxillary Tuberosity. The rounded elevation located at the posterior aspect of both sides of the maxilla. Aids in the retention of dentures.

facial view Coronoid process. A mandibular structure sometimes seen on the maxillary molar periapical film when using the bisecting angle technique with finger retention (The mouth is opened wide, moving the coronoid down and forward). Note the supernumerary molar.

facial view Hamular process (white arrows) and pterygoid plates (purple arrows). The hamular process is an extension of the medial pterygoid plate of the sphenoid bone, positioned just posterior to the maxillary tuberosity.

facial view Zygomatic (malar) bone/process/arch. The zygomatic bone (white/black arrows) starts in the anterior aspect with the zygomatic process (blue arrow), which has a U-shape. The zygomatic bone extends posteriorly into the zygomatic arch (green arrow).

facial view Maxillary sinus. As seen in the above film, the floor of the maxillary sinus flows around the roots of the maxillary molars and premolars. The walls of the sinus may become very thin. As a result, sinusitis may put pressure on the superior alveolar nerves resulting in apparent tooth pain, even though the tooth is perfectly healthy. Note coronoid process (green arrow), zygomatic bone (blue arrow), sinus septum (yellow arrow) and neurovascular canal (orange arrows).

The maxillary sinus is evident anterior to the second molar (black arrows) but it disappears posteriorly due to the superimposition of the zygomatic bone. The orange arrows identify a mucous retention cyst (retention pseudocyst) within the sinus. This film shows the coronoid process (green arrow) and a distomolar (blue arrow) that has erupted ahead of the third molar (red arrow). A distomolar is a supernumerary tooth that erupts distal (posterior) to the other molars.

The zygomatic process (green arrows) is a prominent Ushaped radiopacity. Normally the zygomatic bone posterior to this is very dense and radiopaque. In this patient, however, the maxillary sinus has expanded into the zygomatic bone and makes the area more radiolucent (red arrows). The coronoid process (orange arrow), the pterygoid plates (blue arrows) and the maxillary tuberosity (pink arrows) are also identified.

This film shows the expansion of the borders of the maxillary sinus through pneumatization (red arrows). This expansion increases with age and it may be accelerated as a result of chronic sinus infections. It is most commonly seen when the first molar is extracted prematurely, as in the film at right (the second and third molars have migrated anteriorly to close the space). The coronoid process is seen in the lower left-hand corner of each film. The green arrow identifies a sinus recess. Note the two distomolars in film at right (blue arrows).

Mandibular Incisor a. lingual foramen b. genial tubercles c. mental ridge d. mental fossa d a b c

lingual view facial view d b c a a = lingual foramen c = mental ridge b = genial tubercles d = mental fossa

lingual view Lingual foramen. Radiolucent “hole” in center of genial tubercles. Lingual nutrient vessels pass through this foramen.

lingual view Genial tubercles. Radiopaque area in the midline, midway between the inferior border of the mandible and the apices of the incisors. Serve as attachments for the genioglossus and geniohyoid muscles. May have radiolucent hole in center (lingual foramen), but not on this film. Note double rooted canine (red arrows).

facial view Mental ridge. These represent the raised portions of the mental protuberance on either side of the midline. More commonly seen when using the bisecting angle technique, when the x-ray beam is directed at an upward angle through the ridges.

facial view Mental fossa. This represents a depression on the labial aspect of the mandible overlying the roots of the incisors. The resulting radiolucency may be mistaken for pathology.

The radiolucent area above corresponds to the location of the mental fossa. However, this slide represents chronic periapical periodontitis; these teeth are non-vital, due to trauma. The orange arrows above identify nutrient canals. They are most often seen in older persons with thin bone, and in those with high blood pressure or advanced periodontitis.

Mandibular Canine a = mental ridge b = genial tubercles/ lingual foramen c = mental foramen c a b

facial view lingual view db 22 b d a d c a = mental ridge c = mental foramen b 1 d b 1 = genial tubercles b 2 = lingual foramen

facial view Mental ridge. The raised portions of the mental protuberance, sloping downward and backward from the midline.

lingual view Lingual foramen/genial tubercles. (See description under mandibular incisor above).

facial view The red arrows identify the mandibular canal and the blue arrow points to the mental foramen.

Mandibular Premolar a = mylohyoid ridge b = mandibular canal c = submandibular gland fossa d = mental foramen

facial view d b lingual view a c b = mandibular canal d = mental foramen a = mylohyoid ridge (internal oblique) c = submandibular gland fossa

lingual view Mylohyoid (internal oblique) ridge. This radiopaque ridge is the attachment for the mylohyoid muscle. The ridge runs downward and forward from the third molar region to the area of the premolars.

facial view Mandibular canal. (Inferior alveolar canal). Runs downward from the mandibular foramen to the mental foramen, passing close to the roots of the molars. More easily seen in the molar periapical.

lingual view Submandibular gland fossa. The depression below the mylohyoid ridge where the submandibular gland is located. More obvious in the molar periapical film.

facial view Mental foramen. Usually located midway between the upper and lower borders of the body of the mandible, in the area of the premolars. May mimic pathology if superimposed over the apex of one of the premolars.

The mental foramen (blue arrow) is adjacent to a periapical lesion associated with tooth # 21 (red arrow). There is slight external resorption on # 21. The green arrow points to the mental foramen. The yellow arrow identifies a periapical lesion on # 30. Note the overextension of the silver point in the distal root, the perforation of the mesial root and the amalgam protruding through the perforation from the pulp chamber.

Mandibular Molar a = external oblique ridge b = mylohyoid ridge c = mandibular canal d = submandibular gland fossa

facial view lingual view a b c a = external oblique ridge c = mandibular canal d b = mylohyoid ridge d = submandibular gland fossa

b a d c a = external oblique ridge b = mylohyoid ridge c = mandibular canal d = submandibular gland fossa

facial view External oblique ridge. A continuation of the anterior border of the ramus, passing downward and forward on the buccal side of the mandible. It appears as a distinct radiopaque line which usually ends anteriorly in the area of the first molar. Serves as an attachment of the buccinator muscle. (The red arrows point to the mylohyoid ridge).

lingual view Mylohyoid ridge (internal oblique). Located on the lingual surface of the mandible, extending from the third molar area to the premolar region. Serves as the attachment of the mylohyoid muscle.

facial view Mandibular (inferior alveolar) canal. Arises at the mandibular foramen on the lingual side of the ramus and passes downward and forward, moving from the lingual side of the mandible in the third molar region to the buccal side of the mandible in the premolar region. Contains the inferior alveolar nerve and vessels.

lingual view Submandibular gland fossa. A depression on the lingual side of the mandible below the mylohyoid ridge. The submandibular gland is located in this region. Due to the thinness of bone, the trabecular pattern of the bone is very sparse and results in the area being very radiolucent. The fact that it occurs bilaterally helps to differentiate it from pathology.

The external oblique ridge (red arrows) and the mylohyoid ridge (blue arrows) usually run parallel with each other, with the external oblique ridge always being higher on the film.

The mandibular canal (red arrows identify inferior border of canal) usually runs very close to the roots of the molars, especially the third molar. This can be a problem when extracting these teeth. Note the extreme dilaceration (curving) of the roots of the third molar (green arrow) in the film at left. The film at right shows “kissing” impactions located at the superior border of the canal.

Identify the anatomical structures on the following eight slides. The answers are on the last slide.

Slide # 1 A. The red arrows identify the ?

Slide # 2 A. The red arrow points to the ? B. The white arrows identify the ? C. The blue arrow points to the ? D. The yellow arrow identifies the ?

Slide # 3 A. The small radioluceny identified by the green arrow is the ?

Slide # 4 A. The radiopacity identified by the blue arrows is the ? B. The orange arrow identifies the ?

Slide # 5 A. The yellow arrows point to the ? B. The red arrows identify the ?

Slide # 6 A. The red arrow points to the ? B. The orange arrow points to the ? C. The blue arrows point to the radiolucent line known as the ?

Slide # 7 A. The red arrows point to the ?

Slide # 8 A. The red arrows identify the ? B. What is the name of the radiolucent area surrounding the canal?

KEY Slide # 1: A. Floor of the nasal fossa Slide # 2: A. Coronoid process B. Maxillary sinus (pneumatized into maxillary tuberosity) C. Sinus septum D. Zygomatic process Slide # 3: A. Lingual foramen Slide # 4: A. Mylohyoid ridge B. Submandibular gland fossa Slide # 5: A. Zygomatic process B. Maxillary sinus Slide # 6: A. Inferior concha B. Nasal septum C. Median palatal suture Slide # 7: A. Mental ridge Slide # 8: A. Mandibular canal B. Submandibular gland fossa