Which of the following describes an appropriate technique when performing coronal polishing?

Using a slow speed with controlled movements is the appropriate technique when performing coronal polishing because it enhances precision and minimizes the risk of damaging the tooth surface or soft tissues. A slower speed allows the dental professional to maintain better control over the handpiece, making it easier to navigate around the contours of each tooth while ensuring thorough cleaning.

This technique also helps to reduce the heat generated during polishing, which can protect the pulp tissue from thermal injury. Additionally, controlled movements allow the professional to focus on specific areas, ensuring that plaque and stains are effectively removed without excessive pressure that could lead to enamel abrasion or discomfort for the patient.

In contrast, starting with high-speed rotation could lead to inadequate control and higher risks of damage. Maintaining a handpiece at a 90-degree angle might not be appropriate for all tooth surfaces, as it limits access and may not allow for effective polishing of curved areas. Polishing without any contact would not achieve any cleaning benefits, as the polish requires contact with the tooth surface to be effective.