Which of the following diagnostic criteria is least reliable in the assessment of the pulpal status of the primary dentition?

Electric pulp test. The relatively late appearance of A fibers in the pulp may help to explain why the electric pulp test tends to be unreliable in young teeth, since A fibers are more easily electrically stimulated than C fibers. Accuracy of pulp testing also depends on the patient’s ability to describe how the tooth reacts to stimuli. Clinicians must rely on experience, radiographs, clinical signs or symptoms, and their knowledge of the healing process to assess pulp vitality of young patients.