A

Heavy orthodontic forces compress the periodontal ligament so severely that local blood flow is cut off, producing sterile necrosis (“hyalinization”) of the ligament rather than immediate bone resorption or formation. Animal studies show significantly larger hyalinized areas when heavy (50 g) versus light (10 g) forces are applied to teeth [Kraiwattanapong, 2019, PMID 30896251].