Skeletal changes require sustained application of force to stimulate bone remodeling through the process of bone resorption and apposition. Studies have demonstrated that forces applied for a minimum of 8-10 hours per day are necessary to produce significant and stable skeletal changes without causing damage or unnecessary patient discomfort. Forces applied for less than this duration typically result in insufficient biological response, while continuous force (24 hrs) may lead to adverse effects like root resorption. Hence, 8-10 hrs/day balances effective skeletal remodeling with patient safety and comfort.

Reference: Proffit W, Contemporary Orthodontics, 6th Edition.