Bruxism when the parafunctional activity occurs – during sleep ("sleep bruxism"), or while awake ("awake bruxism"). This is the most widely used classification since sleep bruxism generally has different causes to awake bruxism, although the effects on the condition on the teeth may be the same. The treatment is also often dependent upon whether the bruxism happens during sleep or while awake, e.g., an occlusal splint worn during sleep in a person who only bruxes when awake will probably have no benefit. Some have even suggested that sleep bruxism is an entirely different disorder and is not associated with awake bruxism.
Grinding (abrasive cutting) work in the machining fields, the term "cutting" is often understood to refer to the macroscopic cutting operations, and "grinding" is often mentally categorized as a "separate" process. This is why the terms are usually used separately in shop-floor practice. Lapping and sanding are subsets of grinding. Selecting which of the following grinding operations to be used is determined by the size, shape, features and the desired production rate. "Surface grinding" uses a rotating abrasive wheel to remove material, creating a flat surface. The tolerances that are normally achieved with grinding are ± for grinding a flat material and ±