Space closure and anchorage control

Abstract The ability to close extraction spaces preferentially is an essential skill required during orthodontic treatment. Although many approaches to space closure and anchorage control have been described, the biomechanical principles defining the nature of the force systems applied show many similarities between otherwise diverse techniques. The core concept of anchorage control is the delivery of a differential force system to the anchor teeth relative to the active teeth. Specifically, anchorage is determined by applying unequal moment-to-force ratios (M/F ratios) to each unit. This implies the use of orthodontic appliances that provide either unequal forces or unequal moments. Unequal moment force systems or differential moment force systems are an excellent means of achieving anchorage control. The fundamental concepts and clinical methods of anchorage control are described.