Three-dimensional cone beam computed tomography analysis of temporomandibular joint response to the Twin-block functional appliance

Abstract

Objective: To propose a three-dimensional (3D) method for evaluating temporomandibular joint (TMJ) changes during Twin-block treatment. Methods: Seventeen patients with Class II division 1 malocclusion treated using Twinblock and nine untreated patients with a similar malocclusion were included in this research. We collected their cone beam computed tomography (CBCT) data from before and 8 months after treatment. Segmentations were constructed using ITK-SNAP. Condylar volume and superficial area were measured using 3D Slicer. The 3D landmarks were identified on CBCT images by using Dolphin software to assess the condylar positional relationship. 3D models of the mandible and glenoid fossa of the patients were constructed and registered via voxel-based superimposition using 3D Slicer. Thereafter, skeletal changes could be visualized using 3DMeshMetric in any direction of the superimposition on a color-coded map. All the superimpositions were measured using the same scale on the distance color-coded map, in which red color represents overgrowth and blue color represents resorption. Results: Significant differences were observed in condylar volume, superficial area, and condylar position in both groups after 8 months. Compared with the control group (CG), the Twin-block group exhibited more obvious condyle-fossa modifications and joint positional changes. Moreover, on the color-coded map, more obvious condyle-fossa modifications could be observed in the posterior and superior directions in the Twin-block group than in the CG. Conclusions: We successfully established a 3D method for measuring and evaluating TMJ changes caused by Twin-block treatment. The treatment produced a larger condylar size and caused condylar positional changes.

Three-dimensional morphologic changes in the temporomandibular joint in asymptomatic patients who undergo orthodontic treatment: A systematic review

“…The 13 articles in this review were published between 2014 and 2020. Ten were prospective [24][25][26][27][28][29][30][31][32][33] and 3 were retrospective studies. [34][35][36] Five of the prospective studies were controlled, [26][27][28]30,32 and 5 were not controlled.…”

“…Ten were prospective [24][25][26][27][28][29][30][31][32][33] and 3 were retrospective studies. [34][35][36] Five of the prospective studies were controlled, [26][27][28]30,32 and 5 were not controlled. 24,25,29,31,33 One of the retrospective studies was controlled, 35 whereas 2 were not controlled.…”

“…In terms of the orthodontic appliances prescribed, 7 articles used removable functional appliances; 1 used the Activator appliance, 24 whereas the other 6 used the Twin Block. [25][26][27]30,32,36 Three of the 6 Twin Block studies assigned a comparison treatment group that utilized a separate orthodontic appliance; 1 used a Bionator treatment group, 26 and 2 included a Monoblock treatment group. 25,32 Aside from removable functional appliances, 3 studies used the Herbst appliance.…”

“…28,31 Mean treatment length varied from 6 to 17.5 months, with ranges from 6 to 34 months. Regarding the type of diagnostic assessment used, 8 out of the 13 articles used CBCT, [27][28][29][30][33][34][35][36] 4 used MRI, 25,26,31,32 and 1 used CT. 24 The characteristics of the studies included are summarized in Table III.…”

A long-term longitudinal study of the osteoarthritic changes to the temporomandibular joint evaluated using a novel three-dimensional superimposition method

“…Moreover, the limitation of studies that used an average condylar model was that each condyle differs in its pattern of change and size for each individual with osteoarthritis. Therefore, a new superimposition method was needed to observe osteoarthritic condylar changes 17 – 19 .…”