09 - Periapical Pathoses

radiographic components of teeth

can see enamel, dentin, pulp

• cementum is radiographically indistinguishable from dentin

pathogenesis

apical periodontitis is not the same as periodontal disease

• caused by pulp necrosis → bacterial invasion or tooth trauma

• necrotic pulp metabolites exit root apex and trigger inflammation in PDL and bone, causing apical periodontitis

early-stage vs late-stage caries

• early-stage caries → incipient decay

• late-stage caries -? decay spreads more rapidly in all directions when it passes through DEJ

  • dentin is less mineralized and more prone to decay

  • pulp may recede from decay due to deposition of secondary dentin

periapical inflammatory disease

synonymous terms: apical periodontitis, periapical/radicular/periradicular abscess, periapical/radicular/periradicular granuloma, periapical/radicular/periradicular cyst

• many terms are histopathologic, requiring microscopic confirmation and not radiographic imaging

rarefying vs sclerosing osteitis

• rarefying → increased radiolucency

• sclerosing → increased radiopacity

apical periodontitis

inflammation and destruction of apical periodontium of pulpal origin

• no periapical changes are noted yet

• sometimes cannot be diagnosed by radiographic images alone

• variable presentation → asymptomatic, mild toothache, severe pain and swelling

clinical features of periodontitis

• acute stage

  • severe pain, swelling, fever, lympadenopathy

  • tooth mobile, tender to percussion, may be elevated in socket

• chronic stage

  • may develop from acute lesion or arise de novo

  • often flare-ups of tooth pain

  • tooth may be mobile or percussion-sensitive asymptomatic or with intermittent

imaging examination

purpose to assess extent of lesion and identify involved teeth

• initial imaging → intraoral periapical and occlusal images, panoramic radiographs

• early lesions → subtle changes in periapical tissues

  • diagnosis can rely on clinical signs and symptoms

• long-standing lesions → radiolucency at root apex with surrounding radiopacity

  • imaging appearance varies on disease stage and bone response

• location → mostly apical, but can be accessory canals or root perforations and fractures

  • widening of PDL space

  • loss of lamina dura definition

different radiographic presentations of apical periodontitis

• reactive changes → remodeling of floor of maxillary sinus, with maxillary sinus mucosal thickening

• dense, reactive bone formation → radiopacity around periapical lesions

effects on adjacent teeth

tooth response mirrors bone response

• external resorption → irregular root surface

• hypercementosis → bulbous-shaped roots

• in deciduous teeth, eruption of permanent teeth may be disrupted

lateral radicular cyst

same disease entity as apical periodontitis

• lesions form on lateral portion of root

• pulp has lateral canals which are often microscopic

• bacteria may be in lateral canals

lateral periodontal cyst

originate from epithelial rests in periodontium

• usually unilocular

• multilocular variant exists → botryoid odontogenic cyst

• very well-defined and well-corticated

cemento-osseous dysplasia

benign, fibro-osseous lesion, with teeth remaining vital

• relatively harmless change in bone

• can appear radiolucent, radiopaque, or become more radiopaque and less radiolucent as patient ages

• often confused with apical periodontitis

idiopathic osteosclerosis / dense bone island

can mimic sclerosing osteitis (condensing osteitis)

• PDL space remains uniform

• narrow transition zone between IO and adjacent bone

• sometimes mild root resorption

periapical scar

previous periapical cyst can heal with bone

• occasionally heals with fibrous tissue instead

  • fibrous tissue is radiolucent

• always asymptomatic

• can be difficult to differentiate between periapical scar and periapical cyst radiographically

post-treatment changes

radiolucent areas may persist after successful orthograde or retrograde endodontics

• central radiolucency may represent healing connective tissue

• periophery may show granular bone or radiating trabeculae → “rolled border” or doughnut/fibrous scar pattern

rare cases

• metastatic lesions or blood-borne malignancies may develop in periapical region

• close inspection may reveal subtle cancellous bone destruction