Diagnosis of ‘Root Canal Infection’ depends initially on the symptoms of the tooth.
Symptoms can be classified as subjective symptoms, which are experienced by patient and reported to the clinician. Objective symptoms are those observed by the clinician through tests.
1. Subjective symptoms - The patients chief complaint is the best starting point for correct clinical diagnosis. The completed medical form concerning the patients past medical and dental history consists of subjective symptoms.
Pain - It is the most common complaint of a patient. After the complaint of pain, localization of pain is very important like at a particular tooth or site. Next important part is type of pain like intermittent or continuous type. Duration of pain is also diagnostic. Sometimes the pulpal pain lasts only as long as an irritant is present.
Acute reversible pulpitis is characterized by pain of short duration, caused by specific irritant that disappears as soon as the irritant is removed. If the pain persists, then that kind of pulpitis is irreversible which can be treated by endodontic therapy.
2. Objective symptoms or Signs - These symptoms are observed by the clinician. The tests are as follows: visual and tactile inspection, percussion, palpation, radiograph, electric pulp test, thermal test ( hot and cold), anesthetic test.
Visual and tactile inspection - It is the simplest clinical test. The hard and soft tissues should be checked for “three Cs “ - color, contour and consistency. Color of gingiva is changed from healthy pink color to more reddish in case of infection. A change in contour is noticed due to swelling.
Percussion - In this test first the tooth is struck by a moderate blow with the finger, then with increasing intensity with the handle of the instrument, to determine whether the tooth is tender.
Palpation - This test is done by fingertip using a light pressure to examine tissue consistency and pain response.
Radiograph - It is the most important tool for the clinical diagnosis for root canal treatment. X-rays may show the number, course, shape, length and width of root canals, the presence of any calcified material in the pulp chamber or root canal.
Electric Pulp Testing - It is more accurate than some of the tests used to determine the pulp vitality. The electric tester uses nerve stimulation to check pulp vitality. A positive response is an indication of vitality and helps to determine normality or abnormality of the pulp. No response to electrical stimulus is an indication of pulp necrosis.
Thermal Testing - Application of hot or cold is done on tooth, to check the status of sensitivity on tooth, due to thermal changes. A response to cold indicates vital pulp regardless whether pulp is normal / abnormal. An abnormal response to hot indicates presence of pulpal or periapical disorder.
In case of heat testing hot air blow, hot water, hot instrument, hot gutta percha can be used. The heat is applied first to the top third of the exposed tooth. In case of cold, a stream of cold air can be blown on previously dried tooth and also at gingival margin. The most common way is to wet cotton pellet with ethyl chloride and apply on the tooth.
Anesthetic test - This type of test is mainly performed on the patients who are in pain at the time of test. Objective is to anesthetize the tooth by giving injection, at a time until the pain disappears and is localized to a specific tooth.