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Title

Twin-Block Appliance Outperforms Dynamax Appliance For Class II, Division 1 malocclusion

Clinical Question

In a patient with a Class II, Division 1 malocclusion, is treatment using the Twin-block appliance superior to the Dynamax appliance for better occlusion and esthetics combined?

Clinical Bottom Line

Better results are obtained using Twin-blocks than using Dynamax appliances for patients with Class II Division 1 malocclusion with an over-jet of 6mm or more.

Best Evidence

(you may view more info by clicking on the PubMed ID link)

PubMed ID	Author / Year	Patient Group	Study type (level of evidence)
#1) 20691354	Thiruvenkatachari B 2010	32 boys and 32 girls aged 10-14 Yrs	Randomized Controlled Trial
Key results	At 18 months, the Data Monitoring Committee terminated the Dynamax group due to significantly minimal over-jet and a greater incidence in adverse events and appliance breakage (Twin-block 16%; Dynamax 82%(p<0.001)). The greater increase in reversed over-jet in the Twin-block group was statistically significant (P = 0.04) at 9 months when compared with the Dynamax group. However, this difference was not evident at 12 months. Both groups experienced a similar degree of over-jet and reversed over-jet relapse (1 mm) between the withdrawal of the appliance (9 months) and the final collection of records (12 months).
#2) 17456506	R. T. Lee 2007	28 boys between 11-14 years and 34 girls between 10-13 years	Randomized Controlled Trial
Key results	Skeletal, soft tissue and dental changes in the Twin-block and Dynamax groups were measured pre-and post treatment using three-dimensional optical surface laser scanning, cephalometric, and clinical features. Measurements were made at 3 month intervals with the final evaluations completed at 12 months. Twin-block therapy resulted in more antero-posterior skeletal change, median ANB reduction, larger increases in vertical facial dimension and median total anterior face height increase. A higher percentage of appliance breakage was noted in the Dynamax group (55%) compared to the Twin-block (35%).

Evidence Search

malocclusion [MeSH Terms] AND Twin-block AND Dynamax

Comments on
The Evidence

A randomized controlled trial provides high level evidence. In the Thiruvenkatachari paper, a power analysis determined the size of the experimental groups and treatment was provided by 4 clinicians at 2 centers. Follow-up was every 6 weeks after appliance placement, and over-jet, overbite, molar width, and canine and molar relationship measurements were recorded. Patients were followed for 9 months.In the Lee paper, data were analyzed on an intention-to-treat basis, and the data monitoring committee (DMC) assessors were blinded to treatment allocation. A prospective project was reported. Subjects were matched for gender and age and randomly assigned to the two treatment groups. Group size was determined by conducting a power analysis. A high incidence of appliance breakage was reported in both papers, enough that the Dynamax arm of the Thiruvenkatachari study was terminated and those subjects were completed with Twin-block therapy or fixed appliances. Non-compliance was reported at 9% in both groups.

Applicability

Patients with Class II, Division 1 malocclusion

Specialty/Discipline

(Orthodontics)

Keywords

Twin Blocks, Dynamax, malocclusion

ID#

2075

Date of submission:

07/08/2011

E-mail

faddoul@uthscsa.edu

Author

Taoufik Faddoul

Co-author(s)

Co-author(s) e-mail

Faculty mentor/Co-author

Stephen Matteson, DDS

Faculty mentor/Co-author e-mail

MATTESON@uthscsa.edu

Basic Science Rationale (Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)	post a rationale
None available

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