8. Radiographic interpretation Part 1

radiographic attenuation

The reduction in intensity of an X-ray beam as it travels through matter, caused by absorption or deflection

degree of attenuation depends on the material's thickness, its atomic number, and the energy of the X-ray beam; creates the contrast seen in a radiographic image

Areas w high attenuation, like bone, absorb more X-rays and appear white (radiopaque)

Areas w low attenuation, like air, absorb less and appear black (radiolucent)

photoelectric = absorbed vs compton scattering

high attenuation tissues appear more radiopaque or radiolucent?

radiopaque

low attenuation tissues appear more radiopaque or radiolucent?

radiolucent

bone high attenuation or low attenuation?

high attenuation, radiopaque

air high attenuation or low attenuation?

low attenuation, radiolucent

tissue that attenuates less photons

radiolucent

tissue that attenuates more photons

radiopaque

describe range of radiopaque or radiolucency of enamel, dentin, and cementum

most radiopaque: enamel, dentin, cementum

most radiopaque items

metal and restorations & cements

which is more radiopaque: cortical or cancellous bone?

cortical

75% mineralized

dentin

tooth is primarily composed of

dentin

smooth and homogenous appearance

dentin

radiopaque similar to bone

dentin

cap is present over coronal portion

enamel

90% mineralized

enamel

causes greatest attenuation of x-rays bc of extreme mineralization making it the most radiopaque tissue

enamel

most radiopaque of the dental tooth tissues

enamel

why is it important to identify DEJ?

caries extent

50% mineralized

cementum

thin layer is present over root surface (~2 mm)

cementum

(BLANK) not visualized due to similar radiopacity of (BLANK)

cementum, dentin

what is visualized only with excessive formation

cementum

hypercementosis, only way cementum is visualized

which view can you see cross-section of pulp chambers/canals?

axial

which view can you see mesial and distal of the teeth?

sagittal

which view can you see buccal and lingual of the teeth?

coronal

T or F: apical foramen is recognizable in fully formed teeth

true

T or F: apical foramen is always discernible in last 1 mm of length

false

describe the dental papilla of a developing tooth

root apex is open

radiolucent area surrounded by cortical bone: dental papilla bound by bony crypt

dental papilla

a small, cone-shaped mass of connective tissue located in the center of the developing tooth bud

root apex closed signifies

mature tooth

radiolucency with root apex open signifies

growing tooth

radiolucency with closed root apex signifies

lesion of adult tooth

what closes root apex?

pulpal walls in apical region constrict

close apposition = apex formation

what are the five key supporting dentoalveolar structures?

• lamina dura

• PDL space

• alveolar crest

• cancellous/trabecular bone

• cortical bone (best w CBCT)

lamina dura is

thin layer of cortical bone

which supporting dentoalveolar structure?

• Thin radiopaque layer around the tooth root

• Appearance may vary based on x-ray beam angulation

• Appearance is a valuable diagnostic feature- the presence of an intact (BLANK) around the apex of a tooth strongly suggests a vital pulp

lamina dura

which supporting dentoalveolar structure?

• composed primarily of collagen (soft tissue)

  • appears as a radiolucent line between tooth root and lamina dura

• width varies between individuals, tooth to tooth and location to location

PDL space

widening of PDL space signals

loss of cortical bone (trauma, lesion, inflam)

double PDL space

buccal and lingual eminences on mesial surface of #18 and #19

how does double PDL space occur?

created when x-ray beam directed so that two convexities of root surface appear on image

what could be mistaken for vertical root fracture?

double PDL space

double PDL space of #19

which supporting dentoalveolar structure?

• The gingival margin of alveolar process between teeth

• Appears as a radiopaque line

alveolar crest

alveolar crest is continuation of

lamina dura

alveolar crest is (perpendicular/parallel) to imaginary line connecting (BLANK) of adjacent teeth

parallel, CEJs

normal level of alveolar crest

distance btwn crest and CEJ is under 2mm

alveolar crest

which dentoalveolar structure?

• Lies between cortical plates in both jaws

• Composed of thin radiopaque plates and rods (BLANK1)

• Surrounded by many radiolucent pockets (BLANK 2)

cancellous/trabecular bone BLANK 1: trabeculae BLANK 2: marrow spaces

cancellous bone

anterior/posterior mandible/maxilla:

• Trabeculae are thin & numerous

• Form a fine, granular, dense pattern

• Marrow spaces are small and relatively numerous

anterior maxilla

cancellous bone

anterior/posterior mandible/maxilla:

• Trabeculae are thicker & less numerous (coarser pattern)

• Trabecular plates oriented more horizontally

• Marrow spaces are larger

anterior mandible

cancellous bone

anterior/posterior mandible/maxilla:

• thicker trabeculae, oriented horizontally

• Trabeculae reduce in number inferior to the molar root

posterior mandible

cancellous bone

anterior/posterior mandible/maxilla:

• Finer and more trabeculae than in posterior mandible

• More marrow spaces

posterior maxilla

alteration in number and pattern may suggest disease in asymptomatic pts

in cancellous bone, systemic disease like osteoporosis, renal issue, etc

what are the landmarks of the maxilla?

• intermaxillary suture

• incisive/nasopalatine foramen

• incisive/lateral fossa

which landmark of the maxilla?

radiolucent line in midline of maxilla btwn central incisors surrounded by radiopaque lines of thin cortical bone

intermaxillary suture

intermaxillary suture aka midpalatine suture aka median palatine suture

intermaxillary suture

how do you tell the difference btwn intermaxillary suture and a fracture?

suture is a radiolucent line sandwiched btwn two radiopaque lines

fracture would be only a radiolucent line

incisive/nasopalatine foramen

incisive/nasopalatine foramen

which landmark of the maxilla?

• oral terminus of nasopalatine canal

• Image is found between roots of central incisors

• Ovoid radiolucency (fuzzy outline w sagittal view)

• Varies in shape, size, sharpness

• Shape and size may vary based on differing projection geometry

• Increase in size may indicate a cyst involving the nasopalatine canal

  • cyst is presumed if it exceeds 1 cm

incisive/nasopalatine foramen

if this maxilla landmark is large you should investigate

incisive foramen

incisive foramen

incisive foramen

incisive foramen

incisive/lateral fossa

incisive/lateral fossa

which maxillary landmark?

• Gentle depression near root apex of lateral incisor of maxilla

• Casts a diffusely radiolucent shadow in periapical radiographs

• Often misinterpreted as pathologic condition

• Intact lamina dura may help rule out pathology

incisive/lateral fossa