Normal Radiograph Anatomy for the INBDE

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Reviewed by
Dr. Ari Rezaei
Key Takeaway
Table of Contents

    Normal Radiographic Anatomy for the INBDE

    Understanding what normal radiographic anatomy is important in order to be able to identify when a radiographic finding is abnormal.

    Tooth Anatomy 

    Tooth Anatomy

    We can zoom in and see some additional structures:

    Tooth Anatomy (Zoomed in)

    Additional landmarks:

    Additional Landmarks on Teeth

    Some additional pulp features:

    Additional Pulp Features on Teeth

    In some radiographs, the gingiva can be visible. This will appear as:

    Gingival Shadow on Radiograph

    Additional supporting structures include cancellous/trabecular bone and cortical bone:

    Supporting Structures of Teeth

    Maxillary Region

    There are several other anatomic features that can be recognized in maxillary periapicals.

    Intermaxillary suture

    • Linear or slightly undulating radiolucent line between maxillary central incisors
    Intermaxillary Suture
    Lateral Fossa

    Lateral fossa

    • Diffuse radiolucent region apical and overlying maxillary lateral incisor
    Lateral Fossa
    Lateral Fossa (labeled in blue)

    Canine fossa

    • Diffuse radiolucent region distal to the maxillary canine
    Canine Fossa
    Canine Fossa (labeled in blue)

    Anterior nasal spine

    • diffuse , v-shaped radiopaque region apical to maxillary central incisors
    Anterior Nasal Spine
    Anterior Nasal Spine (labeled in blue)

    Incisive foramen

    • Oval radiolucency in region of maxillary central incisors
    Incisive Foramen
    Incisive Foramen (labeled in blue)

    Nasopalatine canal

    • Radiolucent channel between maxillary central incisors
    Nasopalatine Canal
    Nasopalatine Canal (labeled in blue)

    Nasal septum

    • Vertical radiopaque line at midline superior to central incisor
    Nasal Septum
    Nasal Septum (labeled in blue)


    • Outline of soft tissue
    Nose (labeled in blue)

    Nasolabial fold

    • Outline of soft tissue
    Nasolabial Fold
    Nasolabial Fold (labeled in blue)

    Zygomatic arch

    • Broad, radiopacity projected mostly superior and posterior to maxillary molars
    Zygomatic Arch
    Zygomatic Arch (labeled in blue)

    Zygomatic process of maxilla

    • U-shaped, radiopaque line in region of maxillary molars
    Zygomatic Process of Maxilla
    Zygomatic Process of Maxilla (labeled in blue)

    Floor of maxillary sinus

    • Bottom portion of the pyramidal-shaped cavity above the roots of the maxillary premolars and molars
    Floor of Maxillary Sinus
    Floor of Maxillary Sinus (labeled in blue)
    • The nasal cavity and sinuses can have many variations
    • The nasal cavity and sinus can be normal, not visible, or large
    • The paranasal sinuses can vary in size, shape, and internal septations
    • The sinuses have many variants related to their outline, shape, and internal appearance
    • The size of the maxillary sinus increases as an individual ages until skeletal maturity is gained

    This characteristic “Y” shape is commonly tested!

    Y-shape from maxillary sinus and nasal fossa
    Y-shape from maxillary sinus and nasal fossa (labeled in blue)

    Maxillary tuberosity

    • Radiopaque, rounded prominence distal to maxillary molars
    Maxillary Tuberosity
    Maxillary Tuberosity (labeled in blue)


    • Hook-like, radiopaque process projected posterior to maxillary tuberosity
    Hamulus (labeled in blue)

    Mandibular Region 

    Periapical radiographs in the mandibular posterior region can include anatomic features of the mandible.

    Mandibular Region

    Genial tubercles

    • Poorly defined, irregular, radiopaque region apical to mandibular central incisors
    Genial Tubercles
    Genial Tubercles (labeled in blue)

    Mental ridge

    • Radiopaque, triangular shaped area below the mandibular anterior teeth
    Mental Ridge
    Mental Ridge (labeled in blue)

    Mental foramen

    • Round or oval radiolucency in apical region of mandibular premolars or first molars
    Mental Foramen
    Mental Foramen (labeled in blue)
    • Variant of normal: two on one side or posteriorly positioned (this could be real or tube angulation)

    Submandibular gland fossa

    • Poorly defined, broad radiolucency apical to mandibular molars and premolars
    Submandibular Gland Fossa
    Submandibular Gland Fossa (labeled in blue)

    Inferior Alveolar Canal

    • Curvilinear, radiolucent channel in posterior mandible
    Inferior Alveolar Canal
    Inferior Alveolar Canal (labeled in blue)
    • Variant of normal: anterior looping (shown below), multiple canals, canal diameter large or small
    Inferior Alveolar Canal (Variant)
    Inferior Alveolar Canal (Variant) (labeled in blue)

    Mental fossa

    • Poorly defined, broad, radiolucent region superimposed on mandibular incisor roots
    Mental Fossa
    Mental Fossa (labeled in blue)

    Nutrient canals 

    • Radiolucent lines extending between tooth roots
    Nutrient Canals
    Nutrient Canals (labeled in blue)

    Lingual Foramen

    • Round, radiolucent point apical to mandibular central incisors
    Lingual Foramen


    • Round or oval-shaped radiopacity located on the inside of the mandible
    • Due to the calcification and formation of stones in the major salivary glands

    Mandibular tori

    • Broad radiopacity overlaying the roots of posterior mandibular teeth
    Mandibular Tori
    Mandibular Tori (labeled in blue)

    Cervical burnout

    • This term refers to the radiolucency found just below the CEJ on the root due to anatomical variation or a gap between the enamel and bone covering the root
    • It can appear similarly to caries
    Cervical Burnout
    Cervical Burnout (labeled in blue)

    Sinus pneumatization

    • The continuous physiological process that causes the paranasal sinuses to increase in volume
    • Although it it seems like there is pathology between the roots of tooth 3 and 5, it is just the expanded sinus
    Sinus Pneumatization
    Sinus Pneumatization (labeled in blue)

    Panoramic Features

    There are several common anatomic features recognizable in the panoramic radiograph.

    Panoramic Radiograph
    Panoramic Radiograph (labeled)

    1. Mandibular ramus- Broad radiopaque region in the mandible that connects the body to the condyle and coronoid process
    2. Mandibular angle- Junction of the posterior and inferior border of the mandibular ramus
    3. Condyle- Oval radiopaque process that extends posteriorly and superiorly from the mandibular ramus
    4. Coronoid process- Triangular radiopaque process that extends anterior and superiorly from the ramus
    5. Sigmoid notch- Concavity between the condyle and coronoid process
    6. Antegonial notch- Concavity on inferior border of the mandible
    7. Cervical spine- Irregular, radiopaque column behind the mandible and maxilla
    8. Hyoid- Radiopaque process inferior or even superimposed onto the mandible
    9. External auditory meatus- Radiolucent oval behind the mandibular condyle
    10. Styloid process- Pointed radiopacity behind the mandibular ramus
    11. Glenoid fossa- Thin radiopaque concavity where the condyle meets 
    12. Articular eminence- Radiopaque convexity in front of the glenoid fossa

    Soft tissue features can also superimpose onto the panoramic radiograph.

    Panoramic Radiograph
    Panoramic Radiograph (soft tissues labeled)
    1. Tongue- Creates an arch that superimposes over the mandibular teeth and portions of the maxillary teeth
    2. Soft palate- Creates an arch that superimposes above the tongue
    3. Epiglottis- Radiopaque structure seem behind the tongue 
    4. Oropharynx- Creates a column of soft tissue that superimposes behind the mandible
    5. Nasopharynx- Creates a column of soft tissue that superimposes behind the mandible and is located above the oropharynx

    Now that you know what normal looks like, make sure to check out INBDE Bootcamp's Radiographic Bone Lesions To Know!

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