Two forces of opposite directions and with non-overlapping points of application.
Translation of teeth occurs in response to appropriate force couples.
Potential Complications of Orthodontic Tooth movement
Alveolar bone height
Orthodontic effects on the pulp
Rare if light, continuous forces are applied.
Occasional loss of tooth vitality.
History of previous trauma
Excessive orthodontic forces
Moving roots against cortical bone
Endodontically treated teeth can be moved like natural teeth, with proper management.
More accurately, resorption of root cementum and dentin.
Normal ageing process in many individuals
Likely occurring in many cases but not to the degree of clinical significance.
Root resorption induced by light orthodontic forces is reversible (by regeneration and repair of cementum and/or dentin).
Can lead to tooth mobility in severe cases.
Generalized Root Resorption
Affects most, if not all, teeth; maxillary incisors more susceptible than other teeth.
Could be moderate or severe but commonly in the range of up to 2.5 mm.
Etiology largely unknown but predisposing factors include conical roots with pointed apices, distorted tooth form, or a history of trauma.
Localized Root Resorption
Can’t always be distinguished from generalized root resorption.
Maxillary incisors more susceptible than other teeth.
Only in rare cases can the causes, such as heavy orthodontic forces, be pinpointed.
Etiology largely unknown.
Orthodontic tooth movement remains one of the most successful procedures with predictable outcome in medicine and dentistry. Concept 8
Orthodontics and dentofacial orthopedics requires thorough knowledge in biology (of bone, cartilage, teeth, muscles, nerves and other soft tissues), biomechanics, biometrics, material science, clinical skills and practice management in addition to interpersonal skills.
Why study tooth movement?
Up to 80% of the U.S. population have malocclusion that warrants orthodontic correction.
Currently, 36% of the U.S. population seeks orthodontic treatment (Brunelle et al., 1996) .