**Core Concept:** Balanced occlusion is a crucial aspect of restorative dentistry, aiming to distribute occlusal forces evenly across the dentition, preventing excessive wear, tooth damage, and temporomandibular joint disorders. In simple terms, it ensures that the upper teeth (maxillary) and lower teeth (mandibular) meet symmetrically during function. In this context, the lingual cusps refer to the three rounded projections on the lingual (tongue side) of the maxillary posterior teeth (molars and premolars).

**Why the Correct Answer is Right:** When establishing balanced occlusion, the lingual cusps on the non-working side (opposite side to the side on which the opposing tooth is making contact) of maxillary posterior teeth should contact with the opposing mandibular teeth. In this case, the correct answer is:

**Correct Answer: C.** The lingual cusps of the left side maxillary teeth should contact with the right side mandibular teeth. This ensures proper occlusal balance and prevents excessive wear and damage to the teeth.

**Why Each Wrong Option is Incorrect:**

**A.** This answer is incorrect because lingual cusps on the non-working side should not contact the opposing teeth. Instead, they should contact with the opposing teeth on the same side.

**B.** This answer is incorrect as the lingual cusps on the non-working side should contact with the opposing teeth on the opposite side (right maxillary with left mandibular).

**D.** This answer is incorrect because it suggests that maxillary lingual cusps should contact mandibular lingual cusps, which contradicts the concept of balancing occlusion with opposing teeth on the non-working side.

**Clinical Pearl:** Understanding the concept of balanced occlusion is crucial for dental practitioners as it helps to prevent dental wear, damage, and temporomandibular joint disorders. It is essential to visualize the occlusal plane (the plane formed by the occluding contact of opposing teeth) when assessing and adjusting occlusal contacts in restorative dentistry. This ensures that the occlusal forces are evenly distributed, reducing the risk of dental wear, tooth fracture, and temporomandibular joint disorders.