A complete denture patient presents with angular cheilitis. A review of recent medical examination revealed that vitamin deficiency is not a factor. A possible predisposing factor is:

A closed or insufficient vertical dimension of occlusion is thought to be the one predisposing condition for angular cheilitis, which usually is associated with Candida albicans. Improperly balanced occlusion or poor contour of the denture base are not predisposing conditions for angular cheilitis.