The aim of this study is to evaluate benefits of the method of dental sedation using Target controlled infusion (TCI) combined with Bispectral index (BIS) monitoring in patients with Mental Retardation and challenging behavior.

The intravenous sedation of using of propofol is very effective for dental patients with Mental Retardation and challenging behavior. However, it is very difficult to titrate the dose of propofol for maintaining the adequate sedative depth because of the difficulty of verbal communication with them. Therefore, the infusion of excessive propofol dose elicits the complications and delay of recovery.

Inclusion Criteria:

1. Participants aged 16 or over,
2. American Society of Anesthesiologists (ASA) physical status 1 or 2
3. The treatments of dental caries, endodontics, periodontics and prosthesis were planed
4. Participants had moderate or severe Mental Retardation, and were not completely cooperated with dental treatment

Exclusion Criteria:

1. Patients could communicate and cooperate with dental treatment, but used dental sedation for decrease of the anxiety and the fear about dental treatment or another reasons,
2. Patients needed premedication
3. Patients had uncontrolled or sever medical condition