Endodontic Diagnoses (Chapter 8)

Exam-oriented summary of the endodontic diagnostic categories from Abbott’s classification in Ingle’s Chapter 8 (Tables 8-1 and 8-2). A complete endodontic diagnosis names four elements: the tooth, the pulp/root-canal status, the periapical/periradicular status, and the cause. A normal tissue must still be stated explicitly. See the companion quick-reference in Pulp Condition Diagnosis.

Key principle

Conditions are dynamic, progressing pulpitis -> necrosis -> pulpless/infected, and periapically alternating between acute and chronic. The radiolucency is the central discriminator: it takes several months to appear, so its absence never rules out infection - it only means none was visible when the film was taken.

Pulp & Root Canal conditions

Quick-reference table

“Sensibility” = response to cold / electric pulp test (EPT).

Diagnosis	Symptoms	Pulp test	Percussion / Palpation	Radiograph
Clinically normal pulp	None	Normal, non-lingering	Normal	Normal PDL/lamina dura
Reversible pulpitis - acute	Recent (hours-days); sharp, mild, short (seconds); needs extreme temp; occurs every time stimulus applied	Responds, no lingering	Usually normal (+/- a cracked cusp)	Usually normal
Reversible pulpitis - chronic	Long-standing (months); occasional; sharp but mild, short; extreme temp only	Responds, no lingering	Usually normal	Usually normal; +/- condensing osteitis
Irreversible pulpitis - acute	Recent (days); minor temp triggers; severe -> dull ache; lingers >5 min; may be spontaneous, worse lying down, wakes at night	Often exaggerated/lingering	Often tender if periapex involved	+/- (may be normal early); +/- condensing osteitis
Irreversible pulpitis - chronic	Long-standing; occasional; minor temp; sharp/severe -> dull ache that lingers	Often exaggerated/lingering	Often +/-	+/- widened PDL; +/- condensing osteitis
Pulp necrobiosis (partial necrosis)	Brief stage; mixed pulpitis + infection symptoms; severe/distressing; iced-water swishing may relieve	Mixed / inconclusive	Often tender	Usually normal; no radiolucency
Pulp necrosis - no signs of infection	No thermal symptoms; often trauma history	No response	Normal	Normal PDL/lamina dura
Necrotic and infected pulp	No pulp symptoms; any pain is periapical	No response	Often tender	No radiolucency yet (early); +/- slight PDL widening
Pulpless and infected root canal system	No pulp symptoms; periapical (dull ache / biting)	No response	+/- / tender if acute periapex	Periapical radiolucency present
Previous root treatment - no signs of infection	None; history of prior endo procedure	May or may not respond	Normal	No radiolucency; prior tx evident (adequate or inadequate)
Previous root treatment - infected RCS	Periapical symptoms only	No meaningful pulp response	Often tender	Radiolucency present; prior tx evident
Pulp canal calcification (PCC)	Depends on underlying pulp condition	Less reliable; variable	Depends	Narrowed/invisible canal; must also diagnose pulp state
Pulp hyperplasia (pulp polyp)	Often none; may bleed/pain on eating; a form of irreversible pulpitis	Responds (per pulpitis type)	Usually normal	Large carious lesion; +/- chronic apical periodontitis
Pulp atrophy	None; usually elderly	May or may not respond	Normal	Normal; +/- some PCC

Defining features:

• Clinically normal pulp - no pulpal pathosis requiring treatment (may not be histologically normal).
• Reversible pulpitis - pulp capable of healing with conservative management; provisional diagnosis confirmed only after symptoms resolve. Acute = recent + consistent; chronic = long-standing + occasional. Discriminator vs irreversible: short pain needing extreme temperature change.
• Irreversible pulpitis - pulp not capable of healing; lingering pain on minor temperature change. Acute adds spontaneous/night/lying-down pain; chronic is occasional and long-standing.
• Pulp necrosis - necrobiosis = mixed inflamed + necrotic (infected) tissue (a.k.a. partial necrosis); without infection = necrotic but no coronal bacterial pathway, so no apical periodontitis (often trauma); necrotic and infected = bacteria removing necrotic tissue, brief stage before becoming pulpless.
• Pulpless / previously root-treated - once a radiolucency is present the canal is infected. Previously treated teeth get separate terminology; note the technical standard (adequate vs inadequate) and whether infected. Specify other problems (perforation, untreated/blocked canal, fractured file, etc.).
• Degenerative changes - PCC is a radiographic observation (preferred over “obliteration”); a residual micro-canal always remains, and the underlying pulp state must still be diagnosed. Pulp hyperplasia = granulation-tissue “pulp polyp” in young teeth with large caries; it is a form of irreversible pulpitis.
• Pulp atrophy - normal physiologic ageing change; no treatment, but it reduces pulp-test reliability.

Periapical/Periradicular conditions

Diagnosis	Symptoms	Pulp test	Percussion / Palpation	Radiograph
Clinically normal	None periapically	Per pulp status	Normal	Normal PDL/lamina dura
Acute apical periodontitis - primary	Recent, severe pain; pain to touch/bite	No response (unless reversible/irreversible pulpitis)	Severe TTP, tender palpation	No radiolucency (key feature)
Acute apical periodontitis - secondary	Recent, severe; bite/pressure pain; no thermal	No response	Very tender to percussion	Radiolucency present
Chronic apical periodontitis	None / occasional “awareness”	No response	Not tender; may feel “different”	Radiolucency present
Condensing osteitis	None periapically (per long-standing reversible pulpitis)	Usually responds (pulp often vital)	Not tender	Radiopacity (denser bone)
Foreign body reaction	Usually none; persists despite tx	No response	Not tender	Persistent radiolucency +/- radiopaque material
Acute apical abscess - primary	Recent, severe pain + rapid swelling; pus; +/- fever	No response	Severe TTP, tender palpation	No radiolucency; pus present
Acute apical abscess - secondary	Recent severe pain + rapid swelling; pus; +/- fever	No response	Very tender to percussion	Radiolucency present; pus
Chronic apical abscess	Usually none; may notice a “gum boil”	No response	Not tender; may feel “different”	Radiolucency + draining sinus (trace with GP point)
Facial cellulitis	Spreading facial swelling, fever, unwell; pain	No response	Very tender; lymphadenopathy	Radiolucency; spreading infection (airway risk)
Periapical pocket cyst	Usually none	No response	Not tender (unless infected)	Persistent radiolucency; communicates with canal
Periapical true cyst	Usually none	No response	Not tender (unless infected)	Persistent radiolucency; self-propagating, no canal communication
Periapical scar	None; history of RCT/surgery	No response	Normal	Reduced but persistent radiolucency (fibrous, not bone)

Defining features:

• Clinically normal - no periapical pathosis requiring treatment; any symptoms come from the pulp.
• Apical periodontitis - inflammation of the periapical tissues. Primary acute = severe pain with no radiolucency (bone not yet resorbed); secondary acute = acute exacerbation with a pre-existing radiolucency; chronic = radiolucency with no/occasional symptoms.
• Condensing osteitis - a form of chronic apical periodontitis appearing as a radiopacity (increased bone deposition), typically with long-standing chronic reversible pulpitis (pulp often still vital).
• Foreign body reaction - inflammatory response to extruded material (commonly gutta-percha/cement); persistent radiolucency, often with radiopaque material; histological diagnosis only.
• Apical abscess - localized collection of pus. Primary acute = rapid swelling + pus, no radiolucency; secondary acute = abscess with a pre-existing radiolucency; chronic = a draining sinus (intra- or extra-oral) that may come and go.
• Cellulitis - spreading infection through fascial planes from a periapical abscess; fever/malaise, potentially life-threatening airway compromise; needs urgent active dental treatment, not just antibiotics.
• Cysts - both are forms of chronic apical periodontitis, indistinguishable clinically/radiographically (histological diagnosis only). A pocket cyst communicates with the canal and may heal after RCT; a true cyst has a complete epithelial lining, is self-propagating, and requires surgical removal.
• Periapical scar - fibrous healing (not disease) where the radiolucency shrinks but does not fully resolve; follows treatment of apical periodontitis or endodontic surgery; biopsy not indicated - observe and reassess.

Discriminators to memorise

• No radiolucency + severe pain -> primary acute (periodontitis if no pus, abscess if pus/swelling).
• Radiolucency + symptoms -> secondary acute; radiolucency, asymptomatic -> chronic.
• Radiopacity -> condensing osteitis.
• Draining sinus -> chronic apical abscess.
• Persistent radiolucency after RCT (foreign body, extra-radicular infection, cyst, scar) -> can only be separated histologically.

Source

Compiled from Ingle’s Endodontics 7, Chapter 8 - Abbott, Tables 8-1 and 8-2 and the accompanying condition descriptions. Cross-reference: Pulp Condition Diagnosis and MOC Endodontics.