Which instrument is primarily used to check the occlusion and bite in dental procedures?

The instrument that is primarily used to check the occlusion and bite in dental procedures is articulating paper. This specialized paper allows dental professionals to assess how the upper and lower jaws come together during occlusion and helps identify any high spots or interferences in the bite. The use of articulating paper is crucial for ensuring that dental restorations fit comfortably and functionally with the patient's natural occlusion, preventing issues such as bite misalignment or discomfort after treatment.

Other instruments listed serve different purposes in dental procedures. A flexible spatula is generally used for mixing and applying materials such as dental cements or impression materials, rather than for evaluating bite or occlusion. An impression tray is designed to hold dental impression materials as they are applied in the mouth to capture the shape of teeth or gums, which is also unrelated to directly assessing occlusion. Hand scalers are utilized for scraping away plaque and tartar from teeth surfaces, focusing on oral hygiene rather than occlusal evaluation. Thus, articulating paper is uniquely suited for checking occlusion, making it the correct choice.