Condylar response to functional therapy with Twin-Block as shown by cone-beam computed tomography.
OBJECTIVE
To evaluate the condylar changes through cone-beam computed tomography (CBCT) images in patients treated with Twin-Block functional appliance.


METHODS
In this retrospective study, CBCT images of 30 patients who were treated with the Twin-Block appliance were used. Mandible was segmented and pretreatment and posttreatment (T0 and T1) condylar volume was compared. The angle between sella-nasion-Point A (SNA), angle between sella-nasion-Point B (SNB), angle between Point A-nasion-Point B (ANB), midfacial length (Co-A), mandibular length (Co-Gn), and the distances from right condylion to left condylion (CoR-CoL) were also measured on three-dimensional images. Differences were analyzed with Wilcoxon signed rank tests, and Mann-Whitney U-tests were used to compare the scores of male and female participants. Significance was set at P < .05.


RESULTS
In this study, a decrease in SNA and ANB (P < .05 and P < .01, respectively) and an increase in SNB (P < .01) were found. Additionally, CoR-CoL, Co-Gn, and condylar volume increased at both the left and right sides (P < .01). However, increase at Co-A was not statistically significant (P > .05). Comparison of differences by sex was not statistically significant for all measurements (P > .05).


CONCLUSIONS
Twin-Block appliance increases condylar volume, mandibular length, and intercondylar distance by stimulating growth of condyle in an upward and backward direction.
a  Assistant Professor, Gülhane Military Medical Academy Haydarpasha Education Hospital, Dental Service, Section of Orthodontics, Istanbul, Turkey.
Ersin
E
Yildirim
Seniz
S
Karacay
Mustafa
M
Erkan
D000293:Adolescent; D002508:Cephalometry / Q000379:methods; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008312:Malocclusion, Angle Class II / Q000000981:diagnostic imaging / Q000628:therapy; D008334:Mandible / Q000000981:diagnostic imaging; D008335:Mandibular Condyle / Q000000981:diagnostic imaging* / Q000254:growth & development; D008437:Maxilla / Q000000981:diagnostic imaging; D009295:Nasal Bone / Q000000981:diagnostic imaging; D016382:Orthodontic Appliance Design; D017289:Orthodontic Appliances, Functional; D057887:Overbite / Q000000981:diagnostic imaging / Q000628:therapy; D063173:Retrognathia / Q000000981:diagnostic imaging / Q000628:therapy; D012189:Retrospective Studies; D012658:Sella Turcica / Q000000981:diagnostic imaging; D014716:Vertical Dimension
Condyle; Cone-beam computed tomography; Functional orthopedic appliance; Temporomandibular joint; Twin-Block