Activator (Andresen)

The Andresen Activator is the original functional appliance — the prototype from which all modern removable functional appliances evolved. A single-piece acrylic monobloc that positions the mandible forward and vertically open. Primarily worn at night.

• Single Acrylic Monobloc — One-piece PMMA covering palate and lingual surfaces • Labial Bow — 0.8mm SS wire on maxillary incisors (passive) • Guide Flanges — Acrylic extensions between upper and lower teeth • Posterior Bite Platforms — Acrylic blocks maintaining vertical opening

Positions mandible 5-7mm forward with 4-6mm vertical opening (beyond rest position). Stretch of elevator muscles creates myotatic reflex activity that stimulates condylar growth modification. Bulkier design limits it primarily to nighttime use.

1. Receives scans + construction bite (5-7mm advancement, 4-6mm vertical) 2. 3D-print working models, mount on articulator 3. Wax full monobloc — guide flanges, bite platforms, palatal coverage 4. Bend labial bow (0.8mm), embed in wax 5. Flask and process with heat-cured PMMA 6. Trim and polish 7. QC: Mandibular positioning, occlusion, surface finish

• Acrylic: Heat-cured PMMA (ISO 20795-1), uniform thickness • Labial Bow: 0.8mm ASTM F899 SS, passive • Vertical opening: 4-6mm; Sagittal: 5-7mm • Surface: High-gloss polish on all tissue-contact areas • QC: Articulator verification, passive fit, porosity inspection