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
PubMed ID Author / Year Patient Group Study type (level of evidence) 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). 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	(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	Stephen Matteson, DDS
Faculty mentor 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?) None available
Comments and Evidence-Based Updates on the CAT (FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) by Fauzia Dadarkar, DDS, Shadzi Jebraeili, DDS (San Antonio, TX) on 11/13/2015 A PubMed and Trip database search on this question in November 2015, found a more recent publication by Lee RT et. al (2014, PubMed ID: 23291502). This controlled clinical trial on 103 subjects used cephalograms and 3D optical laser scans, to analyze both the hard and soft tissue effects after 15-month full-time functional appliance therapy with Twin Block and Dynamax appliances. The changes observed were more pronounced with the Twin Block appliance. This study further strengthens the conclusions of this CAT.