Diagnosis of apical periodontitis in root-filled teeth

Root filled teeth are common in adult populations worldwide. When a root-filled tooth causes swelling and/or pain it is usually a sign of infection. In combination with the presence of a periapical bone lesion visible in an intraoral radiograph the diagnosis of apical periodontitis is usually quite straightforward. However, when pain is present but radiographic signs are absent or, in particular, when the tooth is asymptomatic but signs of disease are present at an X-ray the diagnostic process is associated with several uncertainties. Asymptomatic periapical bone lesions indicating apical periodontitis is common in root-filled teeth. Based on the current state of knowledge, it is reasonable to assume that the condition does not pose a serious health problem at a population level. Therefore, it is reasonable for the clinician, in most situations, to adopt a diagnostic strategy that helps to refrain from overdiagnosis. Otherwise many patients will risk costly retreatments or even tooth extractions without significant benefit.

pain is present, but radiographic signs are absent or, in particular, when the tooth is asymptomatic, but signs of disease are present at an X-ray, the diagnostic process is associated with several uncertainties. Asymptomatic periapical bone lesions indicating apical periodontitis are common in root-filled teeth. Based on the current state of knowledge, it is reasonable to assume that the condition does not pose a serious health problem at a population level. Therefore, it is reasonable for the clinician, in most situations, to adopt a diagnostic strategy that helps to refrain from overdiagnosis. Otherwise, many patients will risk costly retreatments or even tooth extractions without significant benefit.

Clinical examination
A medical and dental history of the patient is a prerequisite for clinical examination.
For the root-filled tooth in question, we observe for the following: -Any signs of inflammation in surrounding bony structures -Swelling -Redness -Tenderness -Sinus tracts -Periodontal pocket -Caries -Defective restorations.

Materials/instruments
Standard equipment for clinical dental examination (probe, mirror….) Loupes or microscope.
-Cone-beam computed tomography in certain situations.

Procedure
Common scenarios and diagnostic strategy to avoid overdiagnosis of apical periodontitis (AP).

Scenario 0. An asymptomatic root-filled tooth without signs of AP on intraoral radiographs
AP is absent. No indication for further examination.

Scenario I: A symptomatic root-filled tooth with signs of AP on intraoral radiographs
AP is present.

Scenario II: A symptomatic root-filled tooth without signs of AP on intraoral radiographs
Step 1. Consider first other odontogenic origins of pain.
-Neighboring teeth -Vertical root fracture -Pulpitis in untreated parts of the root canal system -Periodontal abscess -Apical fenestration.
Step 2. If no signs of other odontogenic origin are found consider nonodontogenic origin of pain.
-Referred pain from temporomandibular disorder -Maxillary sinusitis (if from a distal tooth in upper jaw) -Atypical odontalgia ("Phantom Tooth Pain") -Trigeminal neuralgia or other neuropathic pain condition.
Step 3. If no other diagnosis may explain the pain consider a cone-beam computed tomography (CBCT) scan.
-If an apical radiolucency is observed in the scan, then AP is diagnosed as present. -If no bone destruction is seen in the CBCT scan, reconsider other diagnoses (Step 1 and 2) that may mimic the symptoms of AP.

Scenario III: An asymptomatic root-filled tooth with signs of AP on intraoral radiographs
Step 1. Determine the time, since root filling was placed.
Step 2. Assess the size of the radiolucency in, if available, compare with the previous radiographic examinations.
Step 3. Judge the quality of the root filling.
If an intraoral radiographic examination reveals a clearly visible apical radiolucency that has remained unchanged, increased in size, or emerged after a period of 4 years after root canal treatment, this strongly indicates persisting infection and that AP is present. If the quality of root filling is also poor, the diagnosis is almost infallible. Consultation with a colleague or radiologist is recommended. D. Time since root filling > 4 years and the radiolucency is still present but reducing in size continuously. Further healing potential may be present especially if rootfilling quality is good.

Pitfalls and complications
-Asymptomatic small lesions are very common among root-filled teeth.
-It is difficult to determine the exact time required for the healing of apical periodontitis in a root-filled tooth. -It is difficult to determine what should be considered as a sufficient healing of bone destruction to constitute successful outcome of root canal treatment. -Very little is known about potential risks of local or systemic adverse effects due to untreated apical periodontitis in root-filled teeth.