When the sedative takes effect, you will feel more relaxed, which allows treatment to be carried out comfortably. It is not the same as general anaesthesia where you are put to sleep completely. In reality, you remain conscious throughout your sedation appointment, able to understand and respond to requests from your dentist. However, due to the properties of the sedative agents, you will be relaxed throughout the procedure, time will appear to pass very quickly and you may not recall much about the procedure. 

Intravenous does not replace local anaesthesia which is still required to numb your jaw and teeth before your dental procedure.

But it can be done after the sedative effect has kicked in, so that you will not remember much about the local anaesthesia administration. 

Intravenous sedation has been shown to be safe, effective and reliable in providing a pleasant dental experience especially for anxious patients. Whilst it is most often associated with complex treatment and surgery (such as multiple teeth extractions including wisdom teeth surgery, dental implants), intravenous sedation can also be provided to carry out other procedures like dental fillings, crowns, bridges, and root canal therapy.