sensory element of the pulp is still functioning. Test cavity preparation is a last resort as this method is considered invasive and irreversible. It is also unlikely that this procedure would provide any more information than thermal and electric pulp sensibility tests. Therefore, test cavities are not generally used in practice as a means of testing pulp sensibility. Treatment Once the pulp has become inflamed, the tooth can be diagnostically divided into two categories: reversible pulpitis and irreversible pulpitis Reversible This is the condition where the pulp is inflamed and is actively responding to an irritant. This may include a carious lesion that has not reached the pulp. Symptoms include transient pain or sensitivity resulting from many stimuli, notably hot, cold, sweet, water and touch. The pulp is still considered to be vital. This means that once the irritant is eliminated, usually by removal of decay and the placement of a restoration, that the pulp will return to its normal, healthy state. When it becomes painful and decayed the tooth may become known as a "hot tooth" and local anesthetic may not work as well. Irreversible This is the condition where the pulp is irreversibly damaged. The pulp cannot recover from the insult and damage. For example, decay that has reached the pulp of the tooth introduces bacteria into the pulp. The pulp is still alive, but the introduction of bacteria into the pulp will not allow the pulp to heal and it will ultimately result in necrosis, or death, of the pulp tissue. Symptoms associated with irreversible pulpitis may include dull aching, pain from hot or cold (though cold may actually provide relief) lingering pain after removal of a stimulus, spontaneous pain, or referred pain. Clinical signs may include reduced response to electronic pulp testing and painful response to thermal stimuli. Today electronic pulp testers are rarely used for diagnosis of the reversibility of pulpitis due to their unreliable nature. Instead they should only be used to test the vitality of teeth. The pulp of a tooth with irreversible pulpitis may not be left alone to heal. That is at least the general viewpoint of the dental profession, and not every dentist would agree that a dead tooth must be treated. No statistics are known but it is possible to have a trouble-free tooth after irreversible pulpitis, albeit a dead tooth. The tooth may be endodontically treated whereby the