Frankel FR-I

The Frankel FR-I is the standard Function Regulator for Class II Division 1 malocclusion with dental crowding. Developed by Dr. Rolf Frankel in 1967, it uses buccal shields and lip pads — not teeth — as its primary support.

• Buccal Shields — Acrylic shields in upper and lower vestibular folds • Lower Lip Pads — Tear-drop shaped acrylic pads in the lower anterior vestibule • Palatal Bow — 1.2mm SS wire connecting left and right buccal shields • Labial Bow — 1.0mm SS wire on maxillary incisors (passive) • Lingual Crossover Wires — 1.0mm SS wires connecting components • Canine Extensions — Wire loops at distal of maxillary canines

The buccal shields displace the cheeks outward, removing buccinator muscle pressure from the dentition. This allows unopposed tongue pressure to expand the dental arches. Lip pads eliminate abnormal mentalis hyperactivity, promoting forward mandibular development. Minimal tooth contact preserves natural arch form development.

1. Deep impressions capturing full vestibular depth are critical 2. Construction bite: 3-5mm advancement, 3-4mm vertical opening 3. 3D-print working models with full vestibular extension 4. Bend wire framework — palatal bow (1.2mm), labial bow (1.0mm), crossover wires 5. Wax buccal shields and lip pads with minimal bulk 6. Flask and process with heat-cured PMMA 7. Trim shields to precise vestibular extension — no over-extension 8. QC: Verify shield depth, wire position, lip pad placement

• Wire: ASTM F899 SS — 1.2mm palatal bow, 1.0mm labial bow, 1.0mm crossover • Acrylic: Heat-cured PMMA (ISO 20795-1) • Shield thickness: 2.5mm maximum • Lip pad position: 2-3mm from alveolar bone • QC: Vestibular adaptation check, wire framework integrity, shield symmetry