Orthodontic biomechanics

Clear aligner therapy (CAT) has evolved as a viable orthodontic treatment approach as digital technology, biomaterials, and biomechanical principles have advanced over time.It was originally used for mild malocclusions, but improvements in aligner design, attachments and digital treatment planning have led to its use in more complex orthodontic situations. This review will present biomechanical principles that define force delivery and tooth movement control and their clinical implications in challenging patients treated with the use of clear aligners. The effects of aligner material properties, thickness, stress relaxation, staging protocols, and attachment design on the magnitude, direction, and predictability of force are discussed. The biomechanical properties of different tooth movements, such as tipping, bodily movement, rotation, intrusion, extrusion, torque and arch expansion are evaluated, highlighting limitations and opportunities for improving treatment outcomes. KEY WORDS:Clear aligner therapy (CAT) ,Orthodontic biomechanics ,Force delivery