Journal Article

A prospective evaluation of Bass, Bionator and Twin Block appliances

DO Morris, HM Illing and RT Lee

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 20, issue 6, pages 663-684
Published in print December 1998 | ISSN: 0141-5387
Published online December 1998 | e-ISSN: 1460-2210 | DOI:
A prospective evaluation of Bass, Bionator and Twin Block appliances

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A prospective clinical study with a random allocation of 47 patients to three different functional appliance groups was established and compared with a slightly younger control group over a 9-month period. The cephalometric hard tissue changes were assessed in relation to the soft tissue changes produced and the patients were also assessed by three-dimensional (3D) laser scanning of the facial soft tissue. Each 'averaged' appliance group scan was compared with the 'averaged' control group face.

Statistically and clinically significant changes occurred in the group treated with the Twin Block appliance, and to a lesser extent in the group treated with the Bionator appliance. No statistically significant facial soft tissue changes could be demonstrated in the Bass appliance group. Upper lip position remained stable despite the significant overjet reduction attained in the three appliance groups. Lower lip protrusion (up to 3.8 mm), lower lip length (up to 4.0 mm), and soft tissue lower and total face height increased significantly in all appliance groups by varying amounts. The long-term effect of these changes needs to be fully evaluated.

The laser scanning system was found to be a sensitive and accurate method of quantitatively assessing small changes in the soft tissue facial form. Significant changes of the facial tissues in the transverse plane were highlighted by this technique.

Journal Article.  0 words. 

Subjects: Restorative Dentistry and Orthodontics

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