Clinical Study of the Direct Pulp Capping in Primary Teeth

Inclusion Criteria: * No irreversible signs or symptoms of pulpitis in the affected tooth. * Mechanical pulp exposure caused by cavity preparation or trauma, or pulp exposure after decayed tissue removal, with healthy dentin around the pulp exposure. * The size of the exposed pulp\<1 mm. * The morphology of pulp tissue at the pulp exposure is normal, and the bleeding should be able to be controlled within 5 minutes. * X-ray showed that there was no abnormal resorption or fracture of the root and no lesions around the root. Exclusion Criteria: * The child is unable to cooperate with the treatment. * Pulp exposure \> 1 mm. * Irreversible signs or symptoms of pulpitis in the affected tooth. * Abnormal morphology of the pulp tissue at the pulp exposure, much bleeding and inability to stop bleeding. * X-ray shows: abnormal resorption or fracture of the tooth root and lesions around the root. * The parents or the child refused to participate in the experiment.