Mandibular ridge resorption causes
**Core Concept**
Mandibular ridge resorption refers to the loss of alveolar bone and the resulting concavity of the jawbone, typically following tooth extraction. This phenomenon is a result of the remodeling process, where osteoclasts resorb bone tissue, and osteoblasts form new bone, but in cases of tooth loss, the resorption exceeds bone formation.
**Why the Correct Answer is Right**
The correct answer is related to the imbalance between bone resorption and formation. After tooth extraction, the periodontal ligament is lost, and the surrounding bone is subjected to mechanical stress and lack of load-bearing function. This leads to an increase in osteoclast activity, causing bone resorption, and a decrease in osteoblast activity, resulting in inadequate bone formation to replace the lost tissue. The bone resorption is further exacerbated by the lack of occlusal forces, which are essential for maintaining alveolar bone density.
**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect as it does not directly relate to the primary cause of mandibular ridge resorption. While smoking is a risk factor for various oral health issues, it is not the primary cause of mandibular ridge resorption.
**Option B:** is incorrect as it is a potential consequence of mandibular ridge resorption, but not the cause. Protrusion of the lower lip can occur as a result of the resorption of the alveolar bone, but it is not the primary mechanism driving the process.
**Option C:** is incorrect as it does not accurately describe the primary cause of mandibular ridge resorption. While denture wear can lead to changes in the alveolar bone, it is not the primary factor driving the resorption.
**Clinical Pearl / High-Yield Fact**
To prevent or minimize mandibular ridge resorption, it is essential to maintain adequate occlusal forces through proper denture design, occlusion, and jaw function. This can be achieved by ensuring that the denture is well-fitting, and the occlusal scheme is balanced, thereby reducing the stress on the alveolar bone.
**Correct Answer:**