What is a buccal groove?

The buccal groove refers specifically to a groove that extends onto the occlusal surface of a tooth, typically seen in molars. This groove is located on the buccal (cheek) side of the tooth and plays an important role in the anatomy and function of the dental structure. It can help in accommodating the position of the teeth during chewing and assists in the proper alignment of dental bites.

When analyzing the context of the other choices, it’s important to note that a depression on the lingual surface signifies an anatomical feature on the tongue side of the teeth, which does not directly relate to the definition of a buccal groove. The notion of a space between two adjacent teeth refers to a dental gap or diastema, which again differs from a groove's structural definition. Lastly, a type of dental filling does not concern tooth anatomy but rather restorative procedures, making it irrelevant in the context of what's being asked about the buccal groove. Hence, option B is consistent with the recognized dental terminology used to describe this specific aspect of tooth morphology.