Related Experiment Video
Updated: Aug 1, 2026

Measuring the Complete-arch Distortion of an Optical Dental Impression
Published on: May 30, 2019
Three-dimensional changes of the mandibular arch after total arch distalization in skeletal Class III malocclusion
Objectives:
To assess three-dimensional (3D) changes in tooth position, arch dimensions, and gingival levels after mandibular total arch distalization in skeletal Class III malocclusion.
Materials And Methods:
Skeletal Class III patients treated with mandibular total arch distalization using interradicular temporary anchorage devices were analyzed using stepwise 3D superimposition and reorientation of serial cone beam computed tomography (CBCT) and digital casts (N = 19). After mandibular regional superimposition of pre- (T0) and post-treatment (T1) CBCTs, the mandibles were segmented and merged with the corresponding digital casts, generating reoriented, superimposed T0 and T1 digital casts. Changes in individual tooth position, arch dimensions, occlusal plane, and clinical crown height (CCH) were measured.
Results:
Mandibular teeth exhibited posterior movement ranging from 1.74 to 2.50 mm with significant lateral movement of the premolars and increase of inter-premolar width by 2.15-2.66 mm (P < .05). Extrusive movement of the entire dentition excluding the second molar was noted (P < .05), inducing changes of the occlusal plane. The overall changes in CCH were limited to -0.23 to 0.16 mm. CCH significantly increased in the premolars and decreased in the first molar (P < .05).
Conclusions:
Based on a stepwise digital superimposition, mandibular total arch distalization induced complex 3D changes in the mandibular arch, including distalization, extrusion, and increase of interpremolar width. Gingival margins generally were maintained, though mild-to-moderate recession was suggested in around 20% of the premolars, which may require attention.
Related Concept Videos
Compact Bone
Compact bone, also called cortical bone, is the denser, stronger of the two types of bone tissue. It is found under the periosteum and in the diaphyses of long bones, where it provides support and protection. The microscopic structural unit of compact bone is called an osteon, or haversian system. Each osteon is composed of concentric rings of calcified...
Fractures: Bone Repair
Minor fractures with no bone displacement are treated by immobilizing the fractured bone using a cast or splint. However, in the case of fractures with displaced bones, the broken bones are repositioned before immobilization to ensure successful healing without deformation and loss of function. The realignment of fractured bone ends is performed through a process called reduction. If the procedure...
Bones of the Upper Limb: Humerus
Bones of the Lower Limb: Tibia and Fibula
Deformations in a Symmetric Member in Bending
When the member is segmented into tiny cubic elements, it is observed that the primary stress...
Deformation of a Beam under Transverse Loading
The insights from the bending moment diagram extend to...

