RADT W12 Ch 3 (pink), 28 (black) Normal Anatomy - Periapical Films

Cortical bone aka compact bone is the dense outer layer of bone. It appears _____ on a radiograph.

Radiopaque (white)

Cancellous bone aka Spongy bone is between two layers of dense cortical bone. It appears primarily _____ on radiographs but the trabeculae will appear ______.

Cancellous bone appears primarily radiolucent with the trabeculae appearing radiopqaue.

Process: marked prominence or projection of bone

• Radiopaque

• Ex. Coronoid Process of mandible.

Ridge: linear prominence or projection of the bone; might also be called a “line”.

• Radiopaque

• Ex. External Oblique Ridge

Spine: sharp, slender projection of bone

• Radiopaque

• Ex. Anterior Nasal spine

• Radiographic Landmark used in Lateral Head Films for Ortho

Tubercle: small rounded projection, small bump or nodule of bone

• Radiopaque

• Ex. Genial tubercles

Tuberosity: Rounded projection of bone

• Radiopaque

• Ex. Maxillary Tuberosity

What are the 4 space/depression bone landmarks?

1. Canal

2. Foramen

3. Fossa

4. Sinus

Canal: Tubelike passageway through bone that contains nerves and blood vessels

• Radiolucent

• Ex. mandibular canal

Foramen: Short round or oval tube-like opening through a bone that allows the passage of nerves and blood vessels

• Radiolucent

• Ex. Mental Foramen, Incisive Foramen

Fossa: shallow, basin-like depression

• Radiolucent

• Fossa are mainly for the purpose of muscle attachment

• Ex. Submandibular fossa

Canine Fossa is…

The depression in the maxillae lateral to the canine

Sinus: a hallow space/cavity within a bone.

• Radiolucent

• Ex. Maxillary sinus

**when sinuses are infected, they will appear more radiopaque (grayish or white within the sinus area on xray)

Septum: a bony wall or partition that divides two spaces or cavities.

• May be present within the space of a fossa or a sinus.

• Radiopaque

• Ex. Nasal Septum

Suture: an immovable join representing a line of union between adjoining bones of the skull.

• Only found in the skull !

• Radiolucent

• Ex. Medial palatal suture

What is the rules of shadow casting?

The further an object is from the film packet, the more likely the object will appear magnified.

ex. tip of the nose is further from the intraoral film packet, then it will appear magnified.

How does soft tissue appear on a radiograph?

On a radiograph, soft tissue (like the nose, lips, tongue) appears as a faint, lighter gray shadow—less radiopaque than bone/teeth, but more radiopaque than air.

Example: the nose shows as a soft-tissue outline or shadow overlying the anterior maxilla, without distinct internal detail.

16 Bony landmarks of the maxilla

1. Incisive foramen

2. Superior foramina of the incisive canal

3. Medial palatal suture

4. Lateral (canine) fossa

5. nasal cavity

6. nasal septum

7. floor of the nasal cavity

8. anterior nasal spine

9. inferior nasal conchae

10. maxillary sinus - septa

11. maxillary sinus - nutrient canals

12. inverted Y

13. maxillary tuberosity

14. Hamulus

15. Zygomatic process of the maxilla

16. Zygoma

What is the name of this bony landmark?

Incisive foramen (nasopalatine foramen)

• Opening in the bone that is located midline of anterior portion of the hard palate, directly posterior to the maxillary central incisors

• Radiography: small ovoid or round radiolucent area between the roots of the maxillary central incisors.

What is the name of this bony landmark?

Superior Foramina of the Incisive Canal

• Two tiny openings in the bone that are located on the floor of the nasal cavity that join together to form the incisive canal

• Radiography: 2 small round radiolucent openings located superior to the apices of the maxillary central incisors

What is the name of this bony landmark?

Median palatal suture

• immovable joint between the two palatine processes of the maxilla

• Radiography: thin radiolucent line between the maxillary central incisors

What is the name of this bony landmark?

Lateral (canine) fossa

• smooth, depression of the maxilla located just inferior and medial to the infraorbital foramen between the canine and lateral incisors

• Radiography: radiolucent area between the max canine and max lateral incisors

Label all the structures 1-5 of the Maxillary canine area.

1. Lateral fossa

2. Nasal fossa

3. Inverted Y

4. Maxillary sinus

5. Dense radiopaque area caused by overlapping

What is the name of this bony landmark?

Nasal cavity

• pear shaped compartment of bone located superior to the maxilla

  • inferior portion formed by the palatal processes of the maxilla and horizontal portions of the palatine bone.

• Radiography: large radiolucent area above the max incisors

What is the name of this bony landmark?

Nasal Septum - made up of the perpendicular plate of ethmoid bone, vomer, and cartilage

• vertical bony wall dividing the nasal cavity into left and right nasal fossa

• Radiography: vertical radiopaque partition\

What is the name of this bony landmark?

Floor of the Nasal cavity

• bony wall formed by the palatal process of the maxilla and the horizontal portions of the palatine bones

• Radiography: dense radiopaque band of bone above the maxillary incisors.

Label the structures 1-8 found in the Maxillary midline area.

1. Incisive foramen

2. outline of the nose

3. lateral fossa

4. nasal fossa (radiolucent)

5. nasal septum (radiopaque)

6. border of nasal fossa

7. anterior nasal spine

8. medial palatine suture

What is the name of this bony landmark?

Anterior nasal spine

• a sharp projection of the maxilla located at the anterior and inferior portion of the nasal cavity

• Radiography: V-shaped radiopaque area located at the intersection of the floor of the nasal cavity and nasal septum.

What is the name of this bony landmark?

Inferior nasal conchae

• wafer-thin, curved plates of bone that extend from the lateral walls of the nasal cavity

• Radiography: diffuse radiopaque mass of projection within the nasal cavity Z

What is the name of this bony landmark?

Maxillary sinus

• paired cavities of the bone located within the maxilla above the maxillary premolar and molar teeth

• Radiography: radiolucent area located above the apices of the max premolar and molars.

What is the name of this bony landmark?

Septa within maxillary sinus

• bony wall that appears to divide the maxillary sinus into compartments

• Radiography: radiopaque lines within the maxillary sinus

• **number and presence of septa vary depending on the anatomy of the individual

What is the name of this bony landmark?

Nutrient canals within maxillary sinus

• tiny, tube-like passageways through the bone that contain blood vessels and nerves

• Radiography: narrow, radiolucent band bound by two thin radiopaque lines.

What is the name of this bony landmark?

Inverted Y

• intersection of the maxillary sinus and the nasal cavity

• Radiography: radiopaque upside-down Y located above the maxillary canine

  • formed by the intersection of the lateral wall of the nasal fossa and anterior border of the maxillary sinus

What is the name of this bony landmark?

Maxillary tuberosity

• rounded prominence of bone that extends posterior to the third molar region

• Radiography: radiopaque bulge, distal to the third molar region

What is the name of this bony landmark?

Hamulus (Hamular process)

• small hook-like projection of bone extending from the medial pterygoid plate of the sphenoid bone

• Radiography: radiopaque hook-like projection posterior to the maxillary tuberosity area

What is the name of this bony landmark?

Zygomatic process of the maxilla

• bony projection of the maxilla that articulates with the zygoma or malar (cheek) bone

• Radiography: J or U shaped radiopaque structure located superior to the max first molar region.

What is the name of this bony landmark?

Zygoma/Zygomatic bone

• articulates with the zygomatic process

• Radiography: diffuse, radiopaque band extended posteriorly from the zygomatic process of the maxilla

Label the structures 1-6 of the Maxillary premolar area

1. Floor of max sinus

2. maxillary sinus

3. zygomatic process

4. septum in maxillary sinus

5. zygoma

6. inferior border of the zygomatic arch.

Label the structures 1-8 of the Maxillary molar area

1. border of max sinus

2. maxillary sinus

3. zygomatic process

4. zygoma

5. septum in max sinus

6. lower border of zygomatic arch

7. hamulus

8. maxillary tuberosity

9. coronoid process (mandible)

What are the 3 main parts that make up the mandible?

1. Ramus - vertical portion, posterior to the third molar

2. Body - horizontal u-shaped portion from ramus to ramus

3. alveolar process - encases and supports the teeth

Genial tubercles

• tiny bumps of bone on the lingual aspect of the mandible

  • attachment site for genioglossus and geniohyoid muscles

• Radiography: ring-shaped radiopaque structure below the apices of the mandibular incisors

Lingual Foramen

• tiny opening or hole in the bone located on the internal surface of the mandible (lingual)

  • inside the genial tubercles

• Radiographic: small radiolucent dot inferior to the apices of the mandibular incisors

Label the structures 1-6 of the Mandibular midline area.

1. mental ridge

2. nutrient canal

3. nutrient foramen

4. genial tubercles

5. lingual foramen

6. inferior border of the mandible

Nutrient canal of mandible

• vertical radiolucent lines seen in thin areas of bone.

• most often seen in anterior portion of mandible.

Mental ridge

• linear prominence of cortical bone located on the external surface of the anterior portion of the mand.

• Radiography: thick radiopaque band from premolar region to the incisal region

  • often appears superimposed over the mandibular anterior teeth

Mental fossa

• scooped-out, depression of bone located on the external surface of the anterior mandible

• Radiography: radiolucent area above the mental ridge

What is the bony landmark that the white arrows are pointing to?

Mental foramen

• opening or hole in bone located by the mandibular premolar region

• Radiography: small ovoid or round radiolucent area located in the apical region of the mand. premolars.

  • **frequently misdiagnosed as periapical lesion. → black arrows point to a real apical lesion

Mylohyoid ridge

• linear prominence of bone located on the internal surface of the mand

• Radiography: dense radiopaque band that extends downwards and forward from the molar region.

Mandibular canal

• tube-like passageway through the bone travelling the length of the mandible; houses the inferior alveolar nerve and blood vessels

• Radiography: a radiolucent band outlined by two thin radiopaque lines

*not mylohyoid ridge

Internal Oblique Ridge

• a linear prominence of the bone on internal surface of ramus

• *also where mylohyoid ridge is; used for muscle attachment of the tongue

• Radiography: radiopaque band that extends downward and forward from ramus

** when both internal and external oblique ridge is present, external is superior to internal

*white arrows

External Oblique Ridge

• linear prominence located on the external surface of the body of the mandible

• Radiography: radiopaque band extended downwards and forward from the anterior border of the ramus

** when both internal and external oblique ridge is present, external is superior to internal

Submandibular fossa

• scooped-out depression of the bone located on the internal surface of the mandible, inferior to the mylohyoid ridge

  • location of the submandibular salivary gland

• Radiography: radiolucent area in the molar region below the mylohyoid ridge

What is the bony landmark indicated by the black arrows?

Coronoid process

• a prominence of bone on the anterior ramus of the mandible

• Radiography: appears as triangular radiopacity with its apex divided & in the region of the third molar.

• **The coronoid process is the only mandibular structure recorded on maxillary molar periapicals.

Label the landmarks 1-4 of the Mandibular Premolar Area

1. Submandibular fossa

2. PDL space -radiolucent

3. Lamina dura - radiopaque

4. Mental foramen

1. external oblique ridge

2. mylohyoid ridge or internal oblique ridge

3. mandibular canal

4. submandibular fossa

Label all the Mandibular structures.

Label the structures

A - enamel

B - dentin

C - dentino-enamel junction

What are the 3 main anatomical landmarks of the alveolar bone? Describe each briefly.

1. lamina dura - wall of tooth socket; made of dense cortical bone; radiopaque line

2. alveolar crest - most coronal portion of the alveolar bone between teeth; radiopaque

3. periodontal ligament space - space between root and lamina dura; thin radiolucent line

Compare and contrast the anterior and posterior regions of the alveolar bone on a radiograph.

Anterior alveolar bone

• dense radiopaque line

• Appears as a thin, pointed, corticated crest between teeth.

• Height is close to the CEJ line.

• Interdental septa are narrow and sharp.

Posterior alveolar bone

• less dense and less radiopaque than anterior region

• Appears as a broader, flat, less corticated crest between teeth.

• Height still follows CEJ but less sharp.

• Interdental septa are wider and more rounded.

Arrange these landmarks as radiolucent or radiopaque.