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Summary

The aim of the present study was to assess clinical effectiveness of Class II Division 1 malocclusion treatment with Twin block appliance.

Material and methods: analysis of cepahlometric radiographs of 34 Class II Divison 1 patients treated with Twin block appliance was performed before and after treatment. A control group was generated from the normative growth data published by Bhatia and Leighton. The treatment effect was calculated by subtracting the natural growth change from the treatment change. This was then compared to twice the method error to see if the treatment change was clinically significant.

Results: Mean mandibular length as measured from point Art to point Pog increased by 6.4 mm in the Twin–block group compare with 4.1 mm in the control group. The overjet during treatment was reduced by 4.9 mm. Relative to the maxilla upper incisor tipped backward by 6.7° and in the control group natural growth proclined them by 2.4°. Lower incisor after the treatment tipped forward and the angle between long axis of lower incisor and mandibular plane increased by 3.3°, whereas in the control group they stay almost in the same position, proclination only 0.7°.

Conclusions: Twin block appliance clinically significantly increases mandibular length (net effect 2.3 mm) and reduce overjet (net effect 4.9 mm). Modification of the Twin block appliance by acrylic extension to cover the edges of lower incisors reduce dentoalveolar tipping and maximize skeletal changes

Key words: malocclusion, treatment of malocclusion with functional appliances, Twin block.

Received: 22 11 2004

Accepted for publishing: 20 03 2005

Antanas Šidlauskas - D.D.S., PhD, MOrthoRCSEd, assoc. prof. and Head of Clinic of Orthodontics, Kaunas University of Medicine, Lithuania.

Address correspondence to Dr. Antanas Sidlauskas, J.Luksos-Daumanto 6, LT-50106 Kaunas, Lithuania. E-mail: antanas@kaunas.omnitel.net



	Baltic Dental and Maxillofacial Journal

March, 2005, Vol. 7, No. 1 CONTENTS SCIENTIFIC ARTICLES Halitosis Manifestation and Prevention Means for Patients with Fixed Teeth Dentures 3 - 6 Clinical Effectiveness of the Twin Block Appliance in the Treatment of Class II Division 1 Malocclusion 7 - 10 Dental Treatment Needs in Lithuanian Adolescents 11 - 15 Mandibular Pubertal Growth Spurt Prediction. Part One: Method Based on the Hand-Wrist Radiographs 16 - 20 Factors Influencing the Removal of Posts 21 - 23 Oral Hygiene in Children with Type I Diabetes Mellitus 24 - 27 Critical Assessment of Temporomandibular Joint Clicking in Diagnosing Anterior Disc Displacement 28 - 30 © 2005 Stomatologija		Stomatologija 2005; 7 (1): 7-10 288 KB Clinical Effectiveness of the Twin Block Appliance in the Treatment of Class II Division 1 Malocclusion Antanas Šidlauskas Summary The aim of the present study was to assess clinical effectiveness of Class II Division 1 malocclusion treatment with Twin block appliance. Material and methods: analysis of cepahlometric radiographs of 34 Class II Divison 1 patients treated with Twin block appliance was performed before and after treatment. A control group was generated from the normative growth data published by Bhatia and Leighton. The treatment effect was calculated by subtracting the natural growth change from the treatment change. This was then compared to twice the method error to see if the treatment change was clinically significant. Results: Mean mandibular length as measured from point Art to point Pog increased by 6.4 mm in the Twin–block group compare with 4.1 mm in the control group. The overjet during treatment was reduced by 4.9 mm. Relative to the maxilla upper incisor tipped backward by 6.7° and in the control group natural growth proclined them by 2.4°. Lower incisor after the treatment tipped forward and the angle between long axis of lower incisor and mandibular plane increased by 3.3°, whereas in the control group they stay almost in the same position, proclination only 0.7°. Conclusions: Twin block appliance clinically significantly increases mandibular length (net effect 2.3 mm) and reduce overjet (net effect 4.9 mm). Modification of the Twin block appliance by acrylic extension to cover the edges of lower incisors reduce dentoalveolar tipping and maximize skeletal changes Key words: malocclusion, treatment of malocclusion with functional appliances, Twin block. Received: 22 11 2004 Accepted for publishing: 20 03 2005 Antanas Šidlauskas - D.D.S., PhD, MOrthoRCSEd, assoc. prof. and Head of Clinic of Orthodontics, Kaunas University of Medicine, Lithuania. Address correspondence to Dr. Antanas Sidlauskas, J.Luksos-Daumanto 6, LT-50106 Kaunas, Lithuania. E-mail: antanas@kaunas.omnitel.net