What type of injection technique is primarily used for subgingival scaling or root planing?

The type of injection technique primarily used for subgingival scaling or root planing is infiltration anesthesia. This technique is chosen because it allows for localized anesthesia directly at the site of the procedure. Infiltration anesthesia works by depositing the anesthetic agent into the tissues near the target area, effectively numbing the soft tissue and sometimes providing limited pulpal anesthesia in the adjacent teeth.

This is particularly useful in dental hygiene procedures like scaling and root planing, which often involve working in close proximity to the gums and tooth roots. The goal is to facilitate a pain-free experience for the patient, enabling the dental hygienist or dentist to perform thorough cleaning without causing discomfort.

Other techniques mentioned, such as block anesthesia, generally provide a more extensive area of numbness and are often used for more invasive procedures, making them less suitable for localized scaling. Topical anesthesia, while useful for providing surface-level numbness, is not as effective for deeper treatment areas. General anesthesia involves rendering the patient completely unconscious and is typically reserved for more complex surgical procedures, making it unnecessary and overly invasive for routine scaling and root planing. Therefore, infiltration anesthesia is the most appropriate choice for this specific dental procedure.