Which cusps are classified as non-working cusps in dental anatomy?

In dental anatomy, non-working cusps are specific cusps on opposing teeth that do not engage during the chewing process. This classification is important for understanding occlusal relationships and how forces are distributed in the dental arch.

The buccal cusp of the upper (maxillary) molars and the lingual cusps of the lower (mandibular) molars are considered non-working cusps because they do not participate in the significant occlusal contact during lateral movements of the jaw. When a patient chews or grinds their teeth, only specific cusps will contact; thus, the non-working cusps are not involved in the primary function of mastication.

This understanding is critical in restorative dentistry and orthodontics, as proper instrumentation of these cusps can influence occlusal harmony and patient comfort. The other options involve combinations of cusps that do not correctly identify the non-working cusps based on the established functional anatomy of occlusion, which is governed by the movements of the jaws and the positional relationships of the maxillary and mandibular teeth during function.