What type of instrument is known as a scaler in dental hygiene?

The correct choice identifies a scaler in dental hygiene as a hand instrument specifically designed to remove calculus, which is the hardened plaque that accumulates on teeth. Scalers feature sharp edges that enable dental hygienists to effectively scrape away both supragingival (above the gum line) and subgingival (below the gum line) deposits.

This function is crucial in periodontal care, as removing calculus helps to prevent and treat gum disease. Understanding the role of a scaler is fundamental for maintaining oral health, as it facilitates the removal of deposits that can lead to other dental problems if left untreated.

The other options describe different tools or instruments used in dental care, but they do not encompass the primary function of a scaler in dental hygiene. For instance, polishing instruments are meant for enhancing the aesthetics of teeth post-cleaning, and electric instruments aid in surface disinfection rather than direct calculus removal. Additionally, orthodontic tools are specialized for adjusting braces or other orthodontic devices, which is a distinct area of dental practice.