The death of a patient under sedation in New South Wales, Australia, in 2002 has again raised the question of the safety of dental sedation. This study sought answers to 2 questions: Can safe oxygen saturation levels (≥ 94%) be consistently maintained by a single operator/sedationist? Does the additional use of propofol, in subanesthetic doses, increase the risk of exposure to hypoxemia? Three thousand five hundred cases generated between 1996 and 2006 were randomly examined and divided into 2 subcohorts: 1750 patients were sedated with midazolam and fentanyl, and 1750 patients received propofol, in subanesthetic increments, in addition to midazolam and fentanyl. Initial sedation was established using midazolam and fentanyl in both subcohorts. The second subcohort received propofol during times of noxious stimulation. Patient exposure to 2 or more oxygen desaturations below 94% was uncommon. The variables that were significantly associated with low saturations were age, gender, and weight. Neither the dose of midazolam nor the additional use of propofol was a significant risk factor. ASA classification (I or II) was not a determinant of risk. The data, within the limitations of the study, showed that a single operator/sedationist, supported by a well-trained team of nurses, can consistently maintain safe oxygen saturation levels. The additional use of propofol did not increase exposure to hypoxemia.