8. Radiographic Interpretation Part 3

what are the landmarks of the mandible?

• genial tubercles

• lingual foramen

• metal triangle/ridge

• mental fossa

• vascular/nutrient channels

• IAN canal

• mental foramen

• external oblique ridge

• internal oblique ridge/mylohyoid ridge

• submandibular gland fossa

• coronoid process

• inferior border of mandible

genial tubercles

which muscles attach to superior tubercles?

genioglossus

which muscles attach to inferior tubercles?

geniohyoid

radiopaque mass in midline, below the incisors

genial tubercles

genial tubercles

lingual foramen

lingual foramen, saggital

which landmark of the mandible?

• Lingual aspect of midline of mandible

• Region of genial tubercles

• Neurovascular bundles from lingual arteries and nerves

• Sublingual/submental arteries and mylohyoid nerves

lingual foramen

which landmark of the mandible?

• Two radiopaque lines sweeping bilaterally forward and upward toward midline

• Visualized in over-angulated views

mental triangle/ridge

mental triangle/ridge

mental triangle/ridge

which landmark of the mandible?

• Depression on labial aspect of anterior mandible, above mental ridge

• Casts a radiolucent shadow over the roots of mandibular anterior teeth

• Often mistaken for periapical/periodontal disease involving incisor

mental fossa

mental fossa

mental fossa

shows it’s more radiolucent bc it’s not as thick at mental fossa

T or F: the neurovascular bundles appear as radiolucent lines of varying widths

false *fairly uniform width

vascular/nutrient channels

IAN canal

which structure of the mandible?

• Radiolucent linear structure with thin radiopaque superior and inferior borders

• Borders partially or not visualized sometimes

• Anterior extension from mental foramen is rarely visible

IAN canal

IAN only inferior partially visualized

which landmark of the mandible?

• Anterior limit of inferior alveolar nerve canal

• Round/ovoid radiolucent structure

• Apical to second premolar

• May mimic periapical disease if projected over root apices

mental foramen

mental foramen

sagittal, coronal, axial of mental foramen

which landmark of the mandible?

• Continuation of anterior border of ramus

• Thick radiopaque line

• Follows antero-inferior course from third molar area to first molar

external oblique ridge

external oblique ridge

which landmark of the mandible?

• Radiopaque line- sometimes defined but of variable width

• Runs diagonally downward and forward at the level of apices of posterior teeth

internal oblique ridge/mylohyoid ridge

internal oblique ridge/mylohyoid ridge

internal oblique ridge/mylohyoid ridge

submandibular gland fossa

which landmark of the mandible?

• Depression on lingual surface

• Below mylohyoid ridge

• Radiolucent area with sparse trabeculae

• Mistaken for bony lesion

submandibular gland fossa

submandibular gland fossa

which landmark of the mandible?

• Periapical radiograph of maxillary molars- mouth open position

• Triangular radiopacity superimposed over third molar area

• Mistaken for a root fragment

coronoid process

coronoid process of the mandible

coronoid process of the mandible

inferior border of mandible

which restorative material?

amalgam

more radiopaque than enamel bc of metal content

which restorative material?

metal inlays- crowns bc of coverage

more radiopaque than enamel bc of metal content

which restorative material?

stainless steel, gold crown and bridges

radiopacity like other metallic restorations

which restorative material?

porcelain crown and porcelain fused to metal crown, metallic cast post

which restorative material?

Nonmetallic Restorative Materials (Composite-radiolucent and radiopaque types)

• Note: the radiopacity of the radiopaque composite is less than that of amalgam seen in adjacent teeth

• Radiolucent type of composite may mimic carious lesions- outline form and clinical exam helps distinguish the two

which restorative material?

cement liners and bases, under layer restorations so an issue would show as more radiolucent than the bone

which restorative material?

gutta percha (plastic)

which restorative material?

silver point (metallic so more opaque than gutta percha)

which restorative material?

implants