What anatomical structure is primarily responsible for the loss of ridge height after molar tooth extraction?

The anatomical structure primarily responsible for the loss of ridge height after molar tooth extraction is the alveolar process. The alveolar process is the bony ridge in the maxilla and mandible that contains the sockets of the teeth. When a molar tooth is extracted, the loss of stimulation to the alveolar process, which occurs through normal chewing and biting forces, leads to resorption of the bone. This phenomenon occurs because the bone relies on the presence of teeth for maintenance of its height and density. Without the tooth, the alveolar bone loses the mechanical loading that keeps it strong, resulting in a reduction in ridge height over time.

The maxilla and mandible, while they are the bones that support the alveolar process, do not directly account for ridge height loss following extraction. The bucco-lingual surface refers to the surfaces of the teeth and does not play a role in the bony changes that occur after a tooth is extracted. Therefore, the key factor in ridge height loss is the alveolar process itself.