Functional appliance
Dental Procedures
≈ ¥3000-8000
(≈ $430-1150)
2 wk
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Description
Estimated cost for Functional appliance at general public hospitals in China is about ¥2100-6400, and at Grade 3A hospitals about ¥3000-8000, varying by hospital tier and region.
Main Uses
Primary purpose is to harness and redirect natural craniofacial growth for correction of Class II malocclusion (retrognathic mandible or prognath and, less commonly, Class III malocclusion. Key applications include: timing-based interceptive treatment during mixed dentitionages 9–14), improving sagittal jaw relationships, enhancing mandibular function and posture, facilitating neuromuscular adaptation, and reducing need for future orthognathic surgery. Used under supervision of a certified orthodontist following comprehensive diagnosis including clinical exam, radiographs (lateral cephalogram), and study models.
Normal Range
Functional appliances (e.g., Twin-block, Frankel) are not diagnostic laboratory tests with numerical 'values' or quantitative reference ranges; they are clinical orthodontic devices. Therefore, there is no universally defined 'normal range' in terms of numerical metrics. Efficacy is assessed qualitatively and semi-quantitatively via cephalometric measurements (e.g., ANB angle: 2°–4°, SNB: 78°–80°, SNA: 82°–84°), dental cast analysis (e.g., overjet reduction ≥3 mm, molar relationship correction to Class I), and functional improvement (e.g., mandibular advancement ≥4–6 mm, improved lip seal, normalized tongue posture). Treatment duration typically spans 9–18 months.
Low Values - Possible Causes
Inadequate patient compliance (e.g., <12–14 hours/day wear), skeletal maturity exceeding optimal window (e.g., post-peak pubertal growth spurt), severe skeletal discrepancy beyond appliance capacity (e.g., ANB >8°, mandibular deficiency >10 mm), poor appliance design/fabrication (e.g., incorrect bite registration, insufficient activation), and concurrent oral habits (e.g., chronic thumb sucking or mouth breathing undermining neuromuscular retraining).
High Values - Possible Causes
Excessive or unmonitored appliance activation leading to iatrogenic overcorrection (e.g., anterior open bite, excessive mandibular protrusion), premature or inappropriate use in non-growing patients causing dental decompensation rather than skeletal change, concomitant rapid maxillary expansion without coordination, hyperactive masticatory musculature amplifying forces unpredictably, and prolonged retention beyond therapeutic need resulting in relapse-prone instability.