An increasing number of dentists are advertising ''sleep dentistry'', where patients are given powerful sedatives that make them forget their time in the chair.

The Australian Society of Dental Anaesthesiology says greater regulations are needed to protect patients from ''rogue'' dentists who do not have the appropriate training to administer the drugs.

Also referred to as ''twilight sedation'' or ''conscious sedation'', dozens of dental practices across Sydney and NSW advertise sleep dentistry to help patients with dentist phobias or when they are having complicated or prolonged procedures.

Patients are given a combination of sedative and pain-relieving drugs to create a dreamlike state rather than a general anaesthetic.

Society secretary Douglas Stewart warned patients could overdose on the drugs, leading to airway obstruction and possible death.

Dr Stewart said there are about 80 dentists in Australia with full training in giving sedatives intravenously. The University of Sydney runs the only course in the country offering the qualification, which is completed by about six dentists a year.

Dentists without IV training either inject the sedatives straight into patients, spray it up a patient's nose or mix it with syrup or cordial.

''The dentists don't have the formal training to deal with a medical emergency if a drug overdose occurs and don't have the proper equipment to alert them if a patient is in trouble,'' Dr Stewart said.

''Some dental practices use medical doctors, who do not have training as anaesthetists, to administer the drugs.''

Dr Stewart said his organisation is urging the Dental Board of Australia, which regulates the industry, to conduct a survey of all registered dentists to determine what level of sedation they offer and what training they have had.

''We need to regulate the rogues who do not have this training,'' he said. ''There are a lot of dentists who simply don't know what can go wrong.''

The board has issued new guidelines for conscious sedation that come into effect on July 1, with requirements that include assistance either by a registered nurse with training in intensive care or a dentist trained in the monitoring of sedated patients.

Australian Dental Association president Shane Fryer said it supported dentists using sleep sedation if they had the appropriate training, qualifications and experience.

''The [board] guidelines make it clear that there is a requirement for other personnel to be present while dentists are carrying out the procedure to monitor the patient,'' he said.