In the anterior region, the occlusion rim should be set slightly buccal to the ridge to allow for proper lip support and esthetics. This positioning ensures adequate space for the labial flange of the denture, enhancing phonetics and facial contour. Setting the rim directly over the ridge or lingually can cause poor lip support and compromised esthetics, while placement at the midline is irrelevant to buccolingual positioning. Thus, a slightly buccal placement optimizes both function and appearance in denture fabrication.

Reference: Prosthodontics: Principles and Management Strategies, Charles J. Goodacre, Edition 5.