If your dentist is using the pin hole technique, then there is minimal bleeding. Thus in most cases the issue of high blood pressure would not have any adverse consequence. It is always advisable to control the blood pressure before going forward with an implant surgery wherein the gums are cut and the flap is opened for inserting an implant. The most common adverse effect could be excessive or rapid bleeding. Dentists ought to take care of excessive blood loss of patients and also keep haemoglobin level of patients normal. In the event things seem to be going out of control it is best advised to start I.V. drip and keep the volume of blood maintained. Patients may need oxygen if breathing is an issue. Usually the things come under control once the bleeding stops. Dentists may use the normal techniques specially of pressure at the site of bleeding to control bleeding. You may call a maxillofacial surgeon or any senior surgeon to help you if need arises. Constantly monitoring the vital parameters of blood pressure, oxygenation, pulse is important.
Use of aspirating needle and aspirate before giving local anaesthesia to prevent the drug going into the blood vessel directly is vital. Keep handy all the necessary medicines and equipment/s before starting the procedure of surgery to help you deal with the situation without any stress. In most cases the surgeries are uneventful and you may not require outside help.