Where would a right handed operator be advised to sit to restore a large class IV restoration on #9 for a patient?

For a right-handed operator restoring a large Class IV restoration on tooth #9, which is the maxillary right central incisor, the most effective position is to sit at the 11-12 o'clock position. This positioning allows the operator to have optimal visibility and access to the tooth while working within the natural hand and arm movements that a right-handed person typically utilizes.

In this position, the operator is directly facing the patient with the patient's head slightly tilted away, which enhances visibility of the anterior teeth. The right-handed operator can comfortably use their dominant hand to work on the left side of the patient's mouth (the side being treated) while being able to access necessary instruments and materials easily. This also provides adequate space for the operator, ensuring they can work without obstruction.

Furthermore, seating in this position helps to minimize strain on the operator’s body, which is vital during lengthy procedures such as those involved with large restorations. Proper posture and body mechanics are crucial to prevent discomfort or injury, making the 11-12 o'clock position the best choice for this scenario.