Periapical Inflammatory Disease

Normal Radiographic Appearance

• Alveolar bone

• Periodontal ligament (radiolucent line)

• Lamina dura

What is periapical inflammatory disease?

Local inflammatory response of bone around a tooth root

Normal Radiographic Appearance

• Alveolar bone

• Periodontal ligament (radiolucent line)

• Lamina dura

What is periapical inflammatory disease?

Local inflammatory response of bone around a tooth root

What is the most common cause of periapical inflammatory disease?

Pulpal necrosis is most common cause

• Secondary to bacterial, chemical, or physical trauma to pulp

• Most commonly caries

What causes inflammation in PDL and bone?

Metabolites from necrotic pulp exit apex

What are the histopathological manifestation charactered by inflammatory infiltrate?

• Abscess – collection of pus

• Granuloma – formed when body attempts to isolate and eliminate inflammatory response

• Cyst – entrapped epithelial cell rests of Malassez stimulated to proliferate a cyst lining

What structures cannot be differentiated by radiologic imaging?

Periapical abscess, granuloma, and cyst

Define apical periodontitis

• Clinical diagnostic term used in endodontics

• Inflammation of apical periodontium of pulpal origin

• May or may not be apparent on imaging

Define Rarefying Osteitis

• Radiologic diagnosis for inflammatory process associated with bone resorption at tooth apex

• Appears as localized area of increased radiolucency

• Rarefying refers to loss of bone mineralization

• Osteitis refers to inflammation of bone

Define Sclerosing (condensing) osteoitis

• Radiologic diagnosis for inflammatory response associated with bone deposition around tooth apex

• Appears as a relatively diffuse area of increased radiopacity

• Sclerosing refers to increase in bone matrix density (hardening of bone)

• Commonly occurs at periphery of an area of rarefying osteitis

What is the clinical presentation for periapical inflammatory disease?

It may not necessarily correlate with imaging findings and this is a trend with a lot of pathologies

What is the clinical presentation of acute periapical disease?

• Severe pain and swelling

• Pain to palpation and percussion

• Tooth may become mobile

• Drainage of pus through fistula or parulis may relieve pain

What is the clinical presentation of chronic periapical disease?

• Potentially asymptomatic

• Intermittent episodes of pain (acute exacerbations of chronic inflammatory response)

What is the main radiographic exam used to diagnose periapical lesions?

• Intraoral periapical images

• Panoramic – helps if lesion extent is beyond borders of PA

• CBCT may be used if more severe condition beyond periapical inflammatory disease suspected

  • Useful for detecting periosteal new bone formation (osteomyelitis) and bone sequestra (osteonecrosis)

• MDCT may be useful to evaluate soft tissue spread of infection

  • Spread into soft tissue spaces – abscess, cellulitis, Ludwig’s angina

What are some radiographic features of a periapical lesion?

Vary depending on the disease stage

• Early lesions

  • Little to no change

  • Diagnosis may rely on pulp vitality tests and clinical signs/symptoms

• Lamina dura becomes less distinct or lost and PDL widens

  • Periapical radiolucency (PARL)

• Longer-standing lesions

  • Radiolucent region at apex

  • More diffuse surrounding area of radiopacity

Where might you find a periapical inflammatory lesion?

• Around apex or adjacent to apical 1/3 of root

• Epicenter adjacent to apex of involved tooth

  • Migrates apically away from apex as lesion enlarges

• Less commonly adjacent to root surface at the

  • exit of an accessory root canal

  • site of a perforation from root canal instrumentation

  • site of root fracture

What should the periphery to a periapical inflammatory lesion look like?

• Poorly to moderately well-defined

• Smooth, hydraulic contour

• Radiolucent area often has a radiopaque periphery with variably wide transition zone

  • Width depends on amount of sclerosis

  • Reflects chronicity of inflammation—bone deposition/density increases with time

• Rarely well defined, corticated with a narrow zone of transition

What does the internal structure of a periapical inflammatory lesion look like?

• Early changes may be masked by anatomic superimposition

  • Change not apparent until sufficient lamina dura and bone loss

  • Thickness of cortices particularly in mandibular posterior

  • Zygomatic process over maxillary molars

• Earliest change: focal widening of apical PDL space

  • Loss of definition of the adjacent lamina dura

• Most often totally radiolucent

  • No discrete internal mineralization

• Occasionally entirely sclerotic (sclerosing osteitis), but usually some apical PDL space widening

What effects do periapical inflammatory lesions have on the surrounding structure?

• Sclerosis (reactive bone formation)

• Cortical erosion

• Periosteal new bone formation

• Odontogenic mucositis

• Adjacent tooth resorption or hypercementosis

What is sclerosis?

• Sclerotic bone reaction may include

  • Thicker than normal trabeculae

  • Increase in number of trabeculae per unit area

• Reduction in size of marrow spaces and narrowing of minor vascular channels

  • Can reduce local blood supply

• Can extend to adjacent teeth, non-tooth-bearing areas, or to bone borders

What is a periosteal reaction?

• Early stages (small size) have little or no effects

• Enlarges and extends to a bone border (cortex of mandible/maxilla, maxillary sinus)

  • Erodes or perforates the bone surface

  • Stimulates periosteal new bone formation (periosteal reaction)

    • Deposition of paired layers of new bone and connective tissue at surface

    • Halo pattern – adjacent to maxillary sinus (periostitis)

    • Onion skin pattern – at outer cortical bone surface

How does a periosteal reaction affect the periosteum?

Dense soft tissue lining floors of air cavities and covering bone surfaces

• Inner osteogenic layer with mesenchymal stem cells

• Outer connective tissue layer with fibroblasts and collagen

• Sharpey fibers – extensions of collagen that anchor periosteum to bone surface

What else do you see in a periosteal reaction?

• Inflammatory response travels through Haversian and Volkmann canal systems to bone surface

• Response elevates/distends adherent periosteum (limited by Sharpey fibers)

• Simulates stem cell differentiation into osteoblasts

• New bone is deposited

What is odontogenic mucositis?

thickening of mucosal lining (nasal cavity or maxillary sinus) stimulated by inflammatory mediators from periapical inflammatory disease

What are some effects on adjacent teeth?

Mirrors response of bone, may be asymmetric and nonuniform around root

Exteral resoption

Another effect on adjacent teeth, there is change in smooth, tapering root contour

Hypercementosis

Another effect on adjacent teeth, production of additional cementum; bulbous roots

What are some effects on adjacent deciduous teeth?

Displacement and/or disruption of erupting succedaneous (permanent) teeth

Differential diagnoses for periapical inflammatory disease

• Types of periapical inflammatory lesions

  • Periapical/radicular cyst

  • Periapical granuloma

• Normal Anatomy (mental foramen, incisive foramen)

• Dense bone island (DBI; idiopathic osteosclerosis)*

• Other pathology

  • Periapical cemento-osseous dysplasia (PCOD)*

  • Malignancy

What is Periapical Cemento-Osseous Dysplasia?

Imaging characteristics cannot reliably differentiate early radiolucent PCOD from periapical inflammatory disease

• Diagnosis may rely on clinical exam

  • Tooth adjacent to PCOD will be vital

  • Tooth with periapical inflammatory disease will be nonvital

• More mature PCOD lesions demonstrate central internaln radiopacities

• External root resorption is more common in inflammation than PCOD

• PCOD commonly associated with hypercementosis

What is Dense Bone Island?

• Can mimic sclerosing osteitis

• Normal PDL space

• Occasionally can cause root resorption

• Associated tooth tests vital

• Narrow transition zone

  • Periphery is smoother and uniform

  • Sclerosing osteitis has wide transition zone

What is this

Sclerosing osteitis

What is this

Dense Bone Island

How do malignancies manifest in periapical inflammatory lesions?

• Metastatic lesions and blood-borne malignancies (ex. leukemia)

• May develop within the apical periodontal ligament space

• Usually see other surrounding bone changes

  • Multiple, variably sized regions of cancellous bone destruction

How would you differentiate between a cyst and a granuloma?

• Cannot radiographically distinguish cysts from granuloma (or abscess)

  • Rarefying osteitis – umbrella term; radiologic diagnosis describing localized inflammatory condition arising from a necrotic tooth

  • Biopsy needed to distinguish – epithelial lining of cyst

• Features associated with cyst

  • Large growth (> 1 cm)

  • Expansion

  • Displacement of adjacent structures

Endodontically Treated Teeth periapical radiolucency

• Persistent or recurrent inflammatory disease after endodontic treatment

• Possible etiologies

  • Inadequate endodontic treatment

  • Unusual root canal morphology

  • Presence of untreated canal

  • Perforation of root surface

  • Root fracture

• CBCT can help determine etiology of persistent or recurrent disease

• Periapical scar – fibrous healing defect

How would you be able to tell the lesion is from a endodontically treated tooth?

• Periapical scar – fibrous healing defect

• Pattern of healing bone

• Compare imaging over time

• Clinical signs/symptoms

  • Asymptomatic

What is the initial management for periapical radiolucency?

• Don’t automatically assume

• Perform vitality test

• Identify etiology

• Compare to prior radiographs and/or follow-up

What does the periodontium do and what are the components of it?

Supports the teeth in the jaws

• Gingiva

• Periodontal ligament (PDL)

• Cementum

• Alveolar processes of jaws

How does one get periodontal disease?

• Inflammatory response to bacteria in periodontal tissues that may lead to loss of junctional epithelium and bone around teeth

• Dental plaque biofilm plays primary role in initiation

• Cyclic periods of active inflammation and tissue destruction and

  quiescence

What is the incidence of periodontal disease?

• 42% of U.S. adults aged 30–79 years have periodontitis

• Significant increase in prevalence with age

• Defined as having clinical attachment loss (≥3 mm, multiple sites) and probing depths (>3 mm, multiple sites OR >4 mm, single site)

What is gingivitis?

Inflammation of gingiva (swelling, edema, erythema). It does not always progress to periodontitis but periodontitis is always preceded by gingivitis

What is periodontitis?

Pocket formation and/or gingival recession and clinical attachment loss

What are some clinical signs of periodontal disease?

• Clinical signs: bleeding on probing, purulent exudate, tooth mobility

• Usually painless

• Can ultimately lead to tooth loss

How would you clinically and radiographically asses peridontits?

1. Conduct the clinical exam first

2. Image when the clinical exam suggests periodontitis

What would a provider do in a clinical exam?

• Probing, bleeding, purulence, gingival recession, clinical attachment loss, mobility, etc.

• Acts as foundation to justify acquisition of radiographs

What should imaging contribute to from the clinical exam?

Information on periodontal status not derived from clinical exam

What do images provide in terms of periodontits?

A record that can be used to evaluate disease longitudinally

Radiographs are helpful for periodontits in the evaluation of

• Amount of bone present

• Condition of alveolar crests

• Bone loss in furcation areas

• Width of PDL space

• Local irritating factors that increase risk of periodontal disease

  • Calculus

  • Poorly contoured or overextended restorations

  • Root length and morphology and crown-to-root ratio

  • Open interproximal contacts, which may be sites for food impaction

• Anatomic considerations

  • Root proximity

  • Position of the maxillary sinus in relation to a periodontal deformity

  • Position of the mental foramen in relation to the alveolar crest

What is periapical cementoosseous dysplasia?

Non-inflammatory benign fibroosseous lesion

What radiographic modality would you use for periodontal disease?

Intraoral images (BWs and PAs), which have the highest spatial resolution of any modality. However, many radiologic signs of periodontal disease are subtle (early bone loss, changes to PDL space and lamina dura)

What do bitewings serve as for periodontal disease?

The primary imaging choice for periodontal diseases

• Most accurately depict distance between CEJ and interradicular alveolar crest

• Vertical BW - long axis of receptor in vertical orientation to capture bone levels

  • Vertical for pockets > 6mm ; Horizontal generally ok for pockets < 6mm

What do PAs serve as for periodontal disease?

• Evaluation of percentage of root affected by bone loss (crown:root ratio)

• Often distorts relationship between CEJ and crest due to greater variation in vertical angulation (anatomic limitations)

What are some limitations of using intraoral images?

• 2D superimposition prevents effective visualization of infrabony defects

  • Acquire multiple images of same site at different angulations

• Typically underestimate amount of bone loss

• Do not demonstrate soft tissue–to–hard tissue relationships (no information on pocket depth)

• Bone level often measured relative to CEJ position

  • Not valid reference when there is supraeruption or passive eruption in cases of severe attrition

What is the role of a panoramic radiographic in periodontitis?

• Overview of teeth and jaws in single image

• Should NOT be primary imaging tool for evaluation of periodontal diseases

  • Multiple superimpositions and distortions especially in anterior areas

  • Lower spatial resolution

  • Inaccurate measurements of bone loss

• NO evidence supports role for extraoral bitewing images in evaluation of periodontal bone loss

What is the role of a CBCT in periodontitis?

• Advantage: elimination of anatomical superimpositions

• Better visualization of complex vertical and crater defects, furcations, buccal/lingual cortical plate loss

• Limited by artifacts from metallic restoration

• Current evidence does NOT support use for imaging of periodontium

  • Insufficient advantage over intraoral imaging techniques

• May be indicated in guiding surgical management in select cases

What is the appearance of a normal radiograph?

• Thin layer of radiopaque cortical bone overlying crest

  • Lack of cortication can be seen both with and without periodontitis

• Crest is 0.5–2.0 mm apical to CEJ

  • Parallel to imaginary line connecting CEJs of adjacent posterior teeth

  • Peak-like between anterior teeth

• Sharp, well-defined angle between lamina dura and crest

• Coronal PDL space typically thin and uniform

  • May appear slightly wider around premolar and erupting teeth

  • If lamina dura forms sharp angle with crest, likely normal

• Increased radiolucency of crest due to thin buccal/lingual thickness

What are some features of imaging?

• No radiographic changes associated with gingivitis (confined to gingiva)

• Features of periodontitis same as other inflammatory conditions of bone

• Changes in morphology of supporting bone

  • Loss of interproximal crestal bone and bone overlapping buccal/lingual root surfaces

• Changes to trabecular density and pattern

  • Usually combo of bone reduction/loss and formation

  • Acute lesions predominantly display loss - increase in radiolucency due to decrease in number and/or spatial density of trabeculae

  • Chronic lesions have greater component of sclerosis - increase in radiopacity due to increase in thickness and/or spatial density of trabeculae

What are some early changes to look out for in a BW or PA?

• Areas of localized erosion of interproximal alveolar crest

• Anterior: blunting of crests and mild loss of bone height

• Posterior: loss of sharp angle between crest and lamina dura

  • Angle may appear “rounded off” with a more irregular border

• Cortical surface of bone edge may become more diffuse

• Radiographic evidence of bone loss follows disease onset

  • Takes ~ 6-8 months of disease progression until radiographic bone loss evident

What are some defects in morphology of alveolar process and crest?

• Horizontal bone loss

• Vertical bone loss

• Interdental craters

• Furcation defects

• Loss of buccal or lingual cortical plates

What are components to look for in the presence and severity of defects?

They vary regionally via

• Distribution (generalized or localized)

• Severity (mild, moderate, severe)

What is horizontal bone loss?

• Loss in height of alveolar process

  • Crest of buccal/lingual cortical plates and intervening interdental bone resorbed

  • Crest parallels imaginary line joining CEJs of adjacent teeth

• Severity based on bone level relative to root length (distance between CEJ and apex)

  • Within coronal 15%

  • Within coronal 15%–33% of root

  • Beyond (apical to) coronal 33% of root length

• When CEJs of adjacent teeth are at different levels, crest may appear angled

• When teeth supraerupt, bone may not follow → apical position of crest relative to CEJ

  • May occur during passive eruption of severely attrited teeth

  • Bone loss not caused by periodontitis

• Bone loss at a single exam does not indicate current disease activity

  • Reestablishment of crestal cortication is good indicator of stabilization

Horizontal Bone Loss

maxillary second premolar is supraerupted; etiology of low bone level (arrow) relative to CEJ is not necessarily periodontal disease

Horizontal Bone Loss

Passive eruption related to severe attrition; apparent increase in distance from CEJ to bone height (arrows) cannot be attributed to periodontal disease. However, resultant change in bone level relative to the CEJ still may be clinically significant.

What is Vertical (Angular) Bone Loss?

• V- or triangular-shaped defect extending apically from crest along affected root surface

• Crest typically angulated obliquely to line connecting CEJ of affected tooth to adjacent tooth

• Early stage – abnormal widening of PDL space at crest

• Defect walls

  • 3-walled: both buccal and lingual cortical plates intact

  • 2-walled: one of plates resorbed

  • 1-walled: when both plates lost

• Assessment of number of walls

  • Difficult on intraoral images due to superimposition

    • Visualization of pocket depth may be aided by inserting gutta-percha point before imaging

  • Clinical and surgical inspections are best

  • CBCT can help but should not be routinely used

Early stage vertical bone loss

1 wall vertical bone loss

Diagram of vertical bone loss

Vertical Bone loss in stage IV periodontitis

Bone loss confined to region of 1st molars

Gutta-percha used to visualize depth of infrabony defects. (A) image fails to show osseous defect (B) image reveals osseous defect extending to region of apex using gutta-percha

Vertical Bone Loss Examples

Appearance also suggests interdental crater defects

What are interdental craters?

• 2 walled, trough-like defect or depression in crest between teeth

  • Buccal and lingual cortical walls extend further coronally than resorbed bone between them

• Band-like or irregular region of bone with less density at crest

• More dense normal bone adjacent to base of crater

  • More common in posterior segments (broader buccal-lingual dimension)

What is buccal/lingual cortical plate loss?

• Loss of cortical plate overlying tooth root

  • Difficult to detect if lack of bone loss at interproximal region

• May occur alone or with another type of bone loss

• Increase in radiolucency of tooth root near alveolar crest

  • Shape is usually semicircular with depth directed apically

What is furcation involvement?

• Apical extent of bone loss to and beyond furcation level of multirooted teeth

• Widening of PDL space at apex of bony crest of furcation

  • More radiolucent appearing furcation area

• Can be masked by external oblique ridge or root morphology

• Harder to see around maxillary molars (palatal root)

  • Most commonly involved maxillary 1st molar furcation is mesial

  • J shape radiolucency with hook of “J” extending into trifurcation

  • Radiolucent triangle with apex pointing toward furcation

• Definitive diagnosis with clinical exam, sometimes surgical exploration

• CBCT – detailed characterization when needed for treatment planning

What is trabecular bone density?

• Periodontal diseases may stimulate adjacent

  • Loss of bone density (rarefaction) - more common in early or acute lesions

  • Reactive bone formation (sclerosis) - may extend a distance from the periodontal lesion

• Usually see both

• Rarely no apparent change in surrounding bone

• Inflammatory products from lesion may diffuse through maxillary sinus floor to cause regional mucositis

What is the classification of periodontal disease based on?

• Tissue types affected – gingiva only or with involvement of alveolar process

• Staging – disease severity and complexity of management

• Grading – historical rate of progression and future risk of progression

• Association with other conditions – systemic or genetic conditions, combined endodontic-periodontic lesions

What is periodontitis subcategorized into?

Necrotizing periodontal diseases (NPDs), periodontitis, and periodontitis as direct manifestation of systemic diseases

Radiographic appearance of all three of these subcategories is similar

How might you see periodontic lesions in endodontics?

• Inflammatory lesions of periodontal or pulpal origin may develop independently and merge

• One may induce the other

  • Periodontal lesion may extend to apex causing secondary pulpitis

  • Periapical inflammatory disease may extend coronally to crest causing retrograde periodontitis

• Angular defect to apex communicating with periapical rarefying osteitis

  • Usually relatively uniform width

  • Widens slightly at crest creating funnel shape

• May affect one or multiple surfaces of tooth or be circumferential

• Treatment is complicated – both endodontic and periodontal therapy

What are some other conditions affecting periodontium?

Periodontal abscess

• Rapidly progressing destructive lesion

• Usually originates in deep soft tissue periodontal pocket

  • Occurs when coronal portion of pocket becomes obstructed

• Pain, swelling, sometimes draining fistula

• May not be visible changes on imaging if acute

• Radiolucent region develops if persists

  • Round area often superimposed over root

  • Loss of lamina dura on involved surface

  • Bridge of bone may be visible over coronal aspect separating it from crest

• After treatment some of lost bone may regenerate

What are local irritating factors?

• Create environment where disease may develop

• Aggravate existing disease

• Calculus deposits

  • Prevent effective cleansing

  • Most commonly at mandibular incisors

• Defective restorations

  • Poor contours and overhanging margins can accumulate plaque

• Enamel pearls and cervical enamel projections

  • Aberrant enamel formations

  • Commonly in furcation regions of multirooted teeth

  • Alter periodontal attachment

  • Create sites prone to biofilm accumulation

How would you evaluate periodontal theray?

• Signs of successful treatment are occasionally visible

  • Not universally seen

  • No apparent changes in many cases

• Good indicators of disease stabilization

  • Reestablishment of interproximal crestal cortex

  • Reestablishment of sharp angle between cortex and lamina dura

• Other possible indicators of successful treatment

  • Sclerosis of previously radiolucent margins of defect

  • Remineralization of previously radiolucent bone

• X-ray beam angulation and exposure settings may affect crest visibility

  • Too high exposure – black image; thin bone may not be apparent, giving impression bone is resorbed

  • Too low exposed – light image; giving impression of bone growth

• Treatment success and healing best assessed clinically

What are some differential diagnosis of bone loss around teeth?

• Malignant neoplasms (squamous cell carcinoma)

  • More extensive bone destruction of localized region beyond periodontium (invasive pattern)

  • Irregular widening of PDL space along entire length and destruction of the lamina dura

  • Invasive border- poorly defined, ragged or irregular periphery

• Langerhans cell histiocytosis

  • Often manifests as one or more regions of bone destruction around roots of teeth

  • Appearance of “teeth floating in space”

  • Epicenter of bone destruction at mid-root level rather than crest – “scooped-out” with crest less resorbed or intact

• Raise suspicion of other disease if

  • Presence of few adjacent loose teeth when rest of mouth shows no sign of periodontal disease

  • Bone destruction does not have pattern/morphology of periodontal disease (apical progression)

  • Bone destruction has ill-defined borders and lacks a peripheral sclerotic bone response