Biomechanics: what has changed?

With the need to improve the efficiency of orthodontic treatment in terms of treatment speed and appliance aesthetics, various appliances and approaches are introduced into the orthodontic landscape. Biomechanical efficiency was improved through the introduction of skeletal anchorage. Among the techniques that tend to modify the patient's biological response, corticotomy, combined or not with bone and or soft tissue grafting, seems to be the most promising in term of quality rather than for speed of movement. A finite element study showed that by modifying bone density the translation movement tends to be expressed sooner and longer. Regarding the invisible or less visible techniques, the biomechanics of the lingual technique is advantageous for controlling the inclination of the lower incisors, both in the use of bite jumper appliances and during retraction. The enthusiasm with which aligner therapy has invaded the orthodontic scene is at the moment downplayed, as it is evident that for some movements this type of therapy does not offer the biomechanical advantages of fixed therapy, whereas it is indicated for simpler movements, but especially in hybrid therapy, which combines the biomechanical advantages of fixed therapy with the aesthetic advantages of aligner therapy.