This trial is active, not recruiting.

Condition angle class ii
Treatments the herbst appliance, twin block appliance
Sponsor The University of Hong Kong
Start date July 2012
End date October 2017
Trial size 50 participants
Trial identifier NCT02448017, HKCTR-1858


Herbst appliance is one of the most popular fixed functional appliances to treat orthodontic patients with small lower jaws. Since small lower jaws are reported to be one of the main reasons to induce sleep disordered breathing(SDB) of children, Herbst appliance can be used to treat SDB children. Previously no study compared the effects of Herbst appliance therapy with removable functional appliance on airway dimension, so it still remains unclear which kinds of functional appliance is more suitable for improving airway dimension. This study will assess the effect of Herbst appliance on airway dimension and compare the effects with those of twin block appliance (a popular 24 hours used removable functional appliance, and also commonly used to treat adult sleep apnea).

United States No locations recruiting
Other countries No locations recruiting

Study Design

Allocation randomized
Endpoint classification efficacy study
Intervention model parallel assignment
Masking single blind (outcomes assessor)
Primary purpose treatment
(Active Comparator)
Orthodontic functional appliance
the herbst appliance
Orthodontic functional appliance
(Active Comparator)
Orthodontic functional appliance
twin block appliance
Orthodontic functional appliance

Primary Outcomes

The cephalometric measurement of dimensional change of upper way following 2-phase orthodontic treatment
time frame: 3 years two-phase treatment with functional appliance and fixed appliance

Secondary Outcomes

The three-dimensional change of upper way following 2-phase orthodontic treatment in magnetic resonance images
time frame: 3 years two-phase treatment with functional appliance and fixed appliance

Eligibility Criteria

Male or female participants from 11 years up to 17 years old.

Inclusion Criteria: 1. Class II malocclusion Exclusion Criteria: 1. Cleft lip and palate 2. Craniofacial syndrome

Additional Information

Official title Effects of Herbst Appliance Therapy to Improve Airway Dimension
Principal investigator Yanqi Yang
Description Sleep disordered breathing (SDB) is an important paediatric problem. It is estimated that 3.2% to 12.1% of children have habitual snoring and 0.7% to 10.3% have obstructive sleep apnea syndrome (OSAS). Children OSAS is associated with a series of daytime and nighttime signs and symptoms. Nighttime symptoms include heavy snoring, restless sleep, heavy seating and enuresis, etc. Daytime symptoms include excessive daytime sleepiness and abnormal behavior such as aggressiveness and hyperactivity, etc. Untreated OSAS was reported to result in serious morbidity, such as failure to thrive, poor learning, attention deficit and hyperactivity disorder, etc. There is an increasing concern related to sleep disordered breathing(SDB) of children by orthodontists. Since not only the tonsilar and adenoid hypertrophy is the main cause of paediatric OSA, but also craniofacial anomalies such as retrognathic mandible, narrow maxillary palatal arch and increased lower facial height can also contribute to it, orthopedic treatment such as rapid maxillary expansion (RME) and mandibular advancement device (MAD) may potentially permanently cure the children OSA. RME which is used to widen maxilla, thus increasing the nasal cavity and improving the nasal flow, has been thoroughly researched. However, only a few previous studies focused on the treatment effect of MAD for treating OSA children. These studies showed sorts of MAD such as jaw-positioning appliance, mono-block, and Herbst appliance were effective to OSA children, but it remains unclear how to choose a functional appliance, and if there is any treatment difference between removable functional appliance and fixed functional appliance for improving airway dimension.
Trial information was received from ClinicalTrials.gov and was last updated in December 2015.
Information provided to ClinicalTrials.gov by The University of Hong Kong.