An unfavorable ridge slope is most commonly observed in a recent extraction case because the alveolar bone undergoes rapid resorption and remodeling immediately after tooth extraction. This results in an irregular and steep ridge contour, making it difficult to achieve proper denture stability and retention. In contrast, long-term denture wearers typically have more resorbed, flattened ridges. The unfavorable slope compromises the prosthetic base adaptation, requiring careful surgical or prosthetic intervention for optimal denture fit.

Reference: Prosthodontics, Dr. Deepak Nallaswamy, 1st Edition.