Aim : The Purpose of this study was evaluate the risk factors, type and dosage of local anaesthetic applied, type and duration of treatment, and complications associated with the administration of the local anaesthetic. Method: There were absolutely no limitations or specific instructions for inclusion of patients in the study with regard to biological data, type and duration of treatment, or type/branch of local anesthetic to be used. Biological data, Risk factors (eg, cardiovascular, pulmonary, hepatic, metabolic, allergic, CNS disease, pregnancy) Daily medication, Type of dental treatment , Duration of dental treatment , Type and dose of applied local anesthetic. Complications (eg, nausea, vomiting, erythema, urticaria, itching, mucosal edema, anaphylactic shock, Other topics (eg, quality of local Anaesthesia). Result: 1600 Patient contacted, 1100 (68.8%) volunteered to participate in this study, Women accounted for the majority of dental patients (55.3%). The average values for female patients were: age 39.9 ± 16.8 yr; weight, 63.5 ± 10.7 kg; height, 166 ± 10.7 cm. The average values for male patients were: age, 42.8 ± 16.8 yr; weight, 79.4 ± 13.1 kg; height, 177 ± 9.1 cm. All three values reached statistical significance at P < 0.0001 when compared with each other. This study would suggest that today's dental practitioner should be aware that more than 45% of dental patients will have one or more concomitant diseases. Conclusion: Dental Anaesthesia clearly proves to be one of the safest anesthetic procedures compared to general Anaesthesia, with an overall incidence of side effects of 7.6-23.3%, and to regional Anaesthesia, with an incidence of 0.2-19.6%. In dentistry can be further reduced if the following aspects are taken into account. An adequate medical history should be routinely obtained for every dental patient. Doses of local anestheticsAnesthetics with low concentrations of epinephrine should be preferred, since this helps to reduce the incidence of sympathomimetic side effects. The concept of a differentiated Anaesthesia that meets the special requirements of the patient (type and duration of the procedure, risk factors) should be always employed.