A right-handed operator generally begins seated at ____ o'clock and a left-handed operator at _____ o'clock.

A right-handed operator typically starts their position at the 8 o'clock position, while a left-handed operator begins at the 3 o'clock position. This positioning allows right-handed operators to effectively utilize their dominant hand while maintaining a comfortable posture and access to the patient. Similarly, the 3 o'clock position for left-handed operators ensures that they can work efficiently with their dominant hand, providing optimal visibility and access to the area of treatment.

Other positions, such as the 10 o'clock for a right-handed operator or the 4 o'clock for a left-handed operator, may not offer the same level of comfort or efficiency due to the natural angles of working and the ergonomics involved. Thus, the 8 o'clock for right-handed and 3 o'clock for left-handed is the standard to promote effective practice and patient care in dental assisting.