The influence of clasp design on twin block appliances outcome - a prospective randomised, controlled clinical trial

ISRCTN	ISRCTN45965219
DOI	https://doi.org/10.1186/ISRCTN45965219
Protocol serial number	N0188119744
Sponsor	Department of Health (UK)
Funder	Lancashire Teaching Hospitals NHS Trust (UK)

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Plain English summary of protocol

Not provided at time of registration

Dr MJ Trenouth
Scientific

Consultant Orthodontist
Royal Preston Hospital
Sharoe Green Lane North
Fulwood
Preston
PR2 9HT
United Kingdom

Phone	+44 (0)1772 523150
Email	michaeltrenouth@hotmail.co.uk

Primary study design	Interventional
Study design	Randomised controlled trial
Secondary study design	Randomised controlled trial
Study type	Participant information sheet
Scientific title
Study objectives	To discover if incorporating a Southend Clasp on the upper central incisors in the design of the Twin Block Appliance will eliminate or greatly reduce incisor retraction thereby enhancing mandibular advancement.
Ethics approval(s)	Added May 2008: Preston and Chorley and South Ribble Research Ethics Committee on 03/07/2003
Health condition(s) or problem(s) studied	Oral Health: Orthodontics
Intervention	Random allocation of two alternative designs of twin block appliance, one with a Southend clasp on the upper central incisors and one without. The appliances are identical in all other aspects.
Intervention type	Other
Primary outcome measure(s)	Added May 2008: Angulation of the long axis of the upper incisor to the maxillary plane, as measured from a lateral cephalometric radiograph.
Key secondary outcome measure(s)	Added May 2008: 1. Angulation of the long axis of the lower incisor to the mandibular plane 2. Skeletal relationship as measured by angle ANB
Completion date	01/04/2007

Participant type(s)	Patient
Age group	Child
Lower age limit	11 Years
Upper age limit	15 Years
Sex	Not Specified
Target sample size at registration	52
Key inclusion criteria	1. Patients aged 11-15 years 2. Added May 2008: with Class II division 1 malocclusion suitable for functional appliance therapy. The overjet had to be greater than 6mm and ANB angle greater than 4°.
Key exclusion criteria	Added May 2008: Patients with congenital syndromes, obvious asymmetry and prior appliance therapy were excluded.
Date of first enrolment	01/01/2003
Date of final enrolment	01/04/2007

Consultant Orthodontist

Preston
PR2 9HT
United Kingdom

Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not provided at time of registration
IPD sharing plan

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Results article	results	01/03/2012		Yes	No
Participant information sheet	Participant information sheet	11/11/2025	11/11/2025	No	Yes