The effects of the Twin-block appliance treatment on the skeletal and dentolaveolar changes in Class II Division 1 malocclusion.
Class II Division 1 malocclusion is the most frequent problem in the orthodontic practice. During the last ten years treatment with Twin-block functional appliance has gained popularity. The aim of the present study was to analyze the skeletal and dentoalveolar changes in Class II Division 1 malocclusions cases treated with Twin-block appliance.


METHODS
Cephalometric analysis of skeletal and dentoalveolar facial structures of 34 Class II Division 1 patients treated with Twin-block appliance was performed using the same reference system before and after treatment. Longitudinal growth records of persons with excellent occlusion-Bolton standards have been used for the control in order to assess natural growth.


RESULTS
Mandibular length as measured from point Articulare to point Pogonion increased by 4.6 mm in the Twin-block group compare with 2.2 mm in the control Bolton standards group. Skeletal and dentoalveolar relationship between maxillary and mandibular bases improved significantly: ANB angle reduced by 2.3 degrees, overjet reduction was 4.7 mm, postnormal molar position corrected by 3.6 mm.


CONCLUSIONS
Twin-block appliance statistically significantly increases mandibular length by 2.4 mm during 12-month treatment period. With the Twin-block treatment about 40% overjet correction was achieved by skeletal and about 60% by dentoalveolar changes. Correction of postnormal buccal segments in Twin-block group was achieved by the combination of distal movement of the upper molars (0.7 mm dentoalveolar, 0.3 mm skeletal) and forward migration of lower molars (0.9 mm dentoalveolar and 1.7 mm skeletal).
Sidlauskas
Antanas
A
Clinic of Orthodontics, Kaunas University of Medicine, J. Luksos-Daumanto 6, 50106 Kaunas, Lithuania. antanas@kaunas.omnitel.net
D002508:Cephalometry; D002648:Child; D003627:Data Interpretation, Statistical; D003766:Dental Occlusion; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008962:Models, Theoretical; D015588:Observer Variation; D016382:Orthodontic Appliance Design; D017289:Orthodontic Appliances, Functional; D016896:Treatment Outcome