LAB: RADIOGRAPH

from lab manual

enamel & dentin

enamel → most radiopaque structure

dentin → should be uniform in density

cementum

cannot be seen radiographically

is observed commonly and may be mistaken for caries

note the “burnt out” appearance around the enamo-dentinal junction in the radiograph

cancellous bone

the bony trabeculae have a coarser pattern and run horizontally in MN

compare with the finer lace-like pattern in MX

periodontal ligament space

any definite widening in this area suggests the presence of pathology

should be narrow and even around the whole of the root surface that lies within the bone

lamina dura

is a radiographic artifact and it would be unwise to place to critical an interpretation on the variation in its appearance in diagnosis

despite the definite appearance of a white line surrounding the roots of teeth within bone, investigation has revealed that there is no increase in mineralization of the cancellous bone lining the tooth socket

pulp and pulp stones

are clinically evident in both molar teeth

present few problems, their removal is easy from the chamber, although if they become lodged in a root canal they can present difficulties

pulp chamber & larger canals → readily visible on the radiograph

finer canals → those in the DB canal of the MX 1st molar may be more difficult to see

—root canals will never become completely sclerosed in the apical portion of the root

median suture

appears a radiolucent line between the central incisors in the maxilla

anterior nasal spine

appears as a V- shaped radiopacity which lies above or is superimposed on the incisive foramen

nasal septum

separates the two nasal fossae

is seen as a radiopaque white line

nose and lip line

is a definite line across the radiograph

a similar line in both upper and lower anterior radiographs often represents the lip line

maxillary antrum

may extend from the premolars to the tuberosity

the apices of the 2nd premolar and 1st molar lie close to

the floor of this may dip between the roots & may be oculated giving the appearance of a cyst

incisive foramen

the radiolucent circular shadow of this foramen may be superimposed over the apex of a central incisor and so be mistaken for a periapical lesion

mandibular canal

aka: inferior dental canal

runs from the mandibular foramen in the ramus to the mental foramen

seen as a radiolucent band and may lie in close association with the apices of molar and 2nd premolar teeth

extrusion of medicaments and root canal filling materials may damage the inferior dental bundle

mental foramen

located below and distal to the apex of the 1st premolar

may be mistaken for a pathological lesion when it appears close to the apex of one of the premolars, which is due to the angle at which the radiograph is taken

lingual foramen

may be seen as white radiopaque area with a small central radiolucent dot in radiographs of the lower incisor area

nutrient canal

contain blood vessels supplying the bone and occur in both mandible and maxilla

lies between the central and lateral incisors as a vertical radiolucent line

periapical radiolucencies

around the tip of the tooth root

important in endodontic diagnosis

most common radiolucency in the jaws

usually caused by pulpal (nerve) disease

recent lesions in periapical:

• no radiopaque border

• grow faster

long-standing lesions in periapical:

• surrounded by a radiopaque (white) line

• grow slowly

—radiographs cannot confirm if a lesion is a cyst

very early periapical changes

some early changes can be reversible

pulp vitality may still be maintained

seen in cancellous bone around the root apex

• changes include:

  • altered trabecular bone pattern

  • slight increase in radiopacity

periodontal ligament (PDL) changes

widened PDL space is an early sign of disease

• can be seen:

  • around the root apex

  • in the furcation area

• often linked to pulpal pathology

lateral radiolucencies

not associated with the apex

occur along the side of the root

commonly caused by lateral canals

can appear even after endodontic treatment

root fractures and perforations

root fractures → often hard to detect on x-ray

perforations of root or furcation cause:

• rapid bone loss

• diagnosis may be clearer after extraction

condensing osteitis

may not always be of dental origin

not a radiolucency → it is a radiopacity

• caused by:

  • low-grade infection

  • excessive biting forces

• features:

  • no symptoms

  • less radiopaque than enamel

advanced periodontal disease

teeth are usually vital

causes bone loss and bony pockets

seen as lateral bone loss on radiographs

bone loss is due to periodontal pocketing, not pulp disease

• a round radiolucent area may appear over the apex, but:

  • PDL space is narrow and even

  • suggests the lesion is not related to the root

stage one – early cementoma

teeth remain vital

no treatment needed

appears as a radiolucent area

develops slowly over about 6 years

• commonly found near:

• MN incisors

stage two – mixed appearance

tooth is vital

no treatment needed

typical around lower 1st molar region

shows a radiopaque area within the lesion

PDL space remains continuous around roots

2 main methods used to take periapical radiographs

bisecting angle technique

paralleling technique

bisecting angle technique

the X-ray cone is directed at right angles to this bisecting line

film is placed close to the lingual or palatal surface of the tooth

• an imaginary line is drawn:

  • between the long axis of the tooth

  • and the plane of the film

• commonly used when:

  • film placement parallel to the tooth is difficult

paralleling technique

film is placed parallel to the long axis of the tooth

the X-ray cone is directed at right angles to the film

the X-ray tube is positioned further from the patient than in the bisecting technique

• to achieve this:

  • the film must be held away from the tooth, especially in the maxilla

significance of longer distance in paralleling technique

reduces image magnification

produces a more accurate image

allows more parallel x-rays to reach the film

extended cone

often used to help aim the x-ray beam accurately

this led to the incorrect term “long cone technique”

correct name: paralleling technique

advantage & disadvantage of bisecting & paralleling technique