When is the use of a scaler most indicated?

The use of a scaler is most indicated for periodontally involved teeth because these instruments are specifically designed to remove calculus and plaque from the tooth surfaces, particularly in the periodontal pockets where periodontal disease is present. Periodontal disease often leads to the accumulation of calculus that can contribute to further tissue destruction, so effective scaling is essential for managing the disease and promoting periodontal health.

When scaling periodontally involved teeth, the goal is to reduce bacterial load, remove hardened plaque, and facilitate the healing of the gums by eliminating irritants that contribute to inflammation. This process helps to re-establish a healthy environment around the teeth, allowing for better maintenance of periodontal tissues.

In contrast, the other answer choices do not apply as directly to the specific use of a scaler in relation to periodontal disease. Preventive care can involve a variety of instruments and procedures, and while scalers may play a role in maintenance, their primary function is to address existing calculus. Subgingival treatment involves deeper cleaning, but it’s not limited to scalers alone; other tools like curettes may be used as well. Finally, scaling teeth without calculus would be unnecessary, as there would be no deposits to remove, making the use of a scaler inappropriate in such cases.