Dental History The patient's dental history is a valuable aid to the dentist. It provides communication between the dentist and  the  patient,  and  allows  the  dentist  to  trace  the history of the complaint through symptoms described by   the   patient.   Often,   patients   reveal   valuable information  regarding  previous  injuries  to  the  teeth, even   though   they   may   have   occurred   many   years earlier. Clinical Examination A clinical examination of the oral cavity allows the dentist   to   visually   inspect   the   patient's   mouth providing clues to the nature of the patient's problems. Such clinical signs as discoloration of the teeth, crown fracture,  gross  caries,  swelling,  abnormal  soft  tissue, and  a  draining  abscess  can  be  identified  during  a clinical  examination. Radiographs Radiographs of the teeth and bone are one of the most  valuable  diagnostic  tools  the  dentist  has  to evaluate  structures  that  cannot  be  seen  by  clinical examination,  such  as  the  pulp  and  periapical  tissues. The  presence  of  bone  loss  in  the  periapical  area  in response  to  a  necrotic  pulp  can  be  detected  on  a radiograph as a dark area surrounding the apex of the root. The presence of this dark area, or radiolucency, on a dental radiograph is an important feature used to diagnose   pulp   and   periapical   disease.   Periapical pathology appears as radiolucencies on a radiograph. Radiographs  can  also  reveal  possible  causes  of pulpal   injury   before   bone   resorption   occurs.   Root fractures, deep caries, and previous pulp exposures are some  examples  of  possible  causes  of  pupal  injury detected on a radiograph. An accurate radiograph can reveal  root  length,  abnormal  root  curvature,  and abnormal calcification, which is helpful information in determining if the tooth can be treated endodontically. A  radiograph,  properly  exposed  and  processed,  can last indefinitely and provide a permanent record of the condition   of   the   patient   and   be   used   for   future reference.  Comparison  of  the  initial  radiographs  with postoperative  radiographs  is  a  valuable  index  to determine if the treatment was successful. Pulp Testers Two of the common pulp testers used primarily to determine  whether  the  pulp  is  vital  or  necrotic (nonvital) are shown in figure 7-1. Electric current is used to stimulate nerve fibers in the pulp through the dentin  layer.  General  information  about  the  status  of the  pulp  is  obtained  by  comparing  the  response  of  a suspected  tooth  with  that  of  a  normal  tooth  (control tooth)  of  the  same  type  on  the  opposite  side  of  the mouth. The amount of current delivered to a tooth is indicated by a numerical scale. The patient holds the ends  of  the  probe  to  complete  the  circuit.  Higher numbers  on  the  scale  indicate  that  more  current  is delivered  to  the  tooth.  As  the  current  is  increased gradually, the patient is instructed to let go of the probe whenever a sensation is first detected within the tooth. Generally,  the  sensation  is  described  as  a  slight tingling  or  warm  feeling.  The  number  at  which  a response occurs is recorded and compared with the test results of the control tooth. A tooth with a necrotic pulp will  not  respond  to  even  the  most  intense  electrical stimulation.  A  dying  pulp  can  produce  a  variety  of responses,  depending  on  the  state  of  the  pulp  at  the time  of  the  test.  However,  the  number  readings  are relative and cannot be used to diagnose vital pulp. Thermal Sensitivity Test The  thermal  sensitivity  test  exposes  a  tooth  to extremes   in   temperature   and   provides   an   accurate method  of  identifying  the  problem  tooth,  as  well  as determining   the   status   of   its   pulp.   The   two   most common diagnostic tests are cold and heat. COLD  TEST.—The cold test can be done easily by placing a cylinder or stick of ice on the tooth. First, the suspected tooth is isolated and dried, then the ice stick, held in a gauze square, is applied to the cervical area of the tooth. Healthy teeth will respond positively to  a  cold  stimulus,  but  the  sensitivity  should  resolve quickly.  If  the  pulp  is  inflamed,  the  patient  will Figure 7-1.—Two common pulp testers. 7-2