Study to Measure the Effect of Part Time Versus Full Time Orthodontic Appliance Wear

A Prospective Randomised Controlled Trial Investigating the Skeletal and Dental Effects of a Removable Brace That Works on the Upper and Lower Teeth at the Same Time Worn Part Time Versus Full Time

The aim of this study is to assess skeletal (bone) and dental (teeth) changes occurring following wear of a twin block functional appliance (removable brace which postures the lower jaw forward to improve a discrepancy between the upper and lower jaw) for differing time periods.

Functional appliances are ordinarily worn full time in adolescence between 11 and 14 years with a discrepancy between their upper and lower jaws. The reason it is worn between these ages is to avail of the pre pubertal growth spurt, evidence for full time wear is merely empirical.If this appliance only had to be worn part time it would have a significant change in orthodontics in terms of patient acceptance and compliance.The investigators plan on recruiting 84 patients to the study and these subjects will be referred from hospital colleagues. The investigators will randomly allocate the subjects into 2 groups, Group 1 will wear the appliance Full Time(24hours), group 2 will wear the appliance part time(12hours). The study will be conducted in the Dental Institute at the Royal London Hospital, this hospital setting will be the sole site. The study will last for 15 months from the time the last patient is recruited. Participants will undergo an initial records appointment where a radiograph and clinical measurements will be taken followed by 12 months of functional appliance treatment where the patient will be reviewed at 6-8weekly intervals and clinical measurements taken.A final radiograph will be taken at 15months.

The Modified Clark Twin Block is a type of functional orthodontic appliance used to posture the lower jaw forward to treat discrepancies between the upper and lower jaw bones

the initial overjet will compared to the final overjet following 12 months of appliance treatment, and 3 months of relapse. overjet will be measured with an orthodontic ruler at every review appointment

Subjective (patient completed time charts) and objective (theramon micro-sensor) measures of wear will be assessed over 12months of appliance wear.

Inclusion Criteria: Class II div 1 malocclusion(upper front teeth lying more forward than lower front teeth with upper front teeth proclined), Overjet(horizontal difference between upper and lower front teeth) measuring minimum of 7mm, Male subjects 12--14 years at the start of treatment, Female subjects 11--13 years at start of treatment, Willingness of the patient and parent to participate in the study. Exclusion Criteria: No previous orthodontic treatment No relevant medical history or craniofacial syndrome

Parekh J, Counihan K, Fleming PS, Pandis N, Sharma PK. Effectiveness of part-time vs full-time wear protocols of Twin-block appliance on dental and skeletal changes: A randomized controlled trial. Am J Orthod Dentofacial Orthop. 2019 Feb;155(2):165-172. doi: 10.1016/j.ajodo.2018.07.016.