When centric occlusion (CO) and centric relation (CR) do not coincide in a complete denture patient, it results in uneven and unstable contacts during jaw closure. This discrepancy causes premature contacts and traumatic occlusal forces, leading to irritation and inflammation of the mucosa. The resulting tissue trauma manifests as soreness beneath the denture-bearing areas, compromising patient comfort. Proper alignment of CO and CR is essential to distribute forces evenly and prevent mucosal injury, thereby avoiding soreness.

Reference: Prosthodontics, Shillinburg HT, 5th Edition.