| Field | Value |
|---|---|
| ID | OA-0336 |
| Type | expander |
| Category | expander |
| Fixed/removable | fixed (banded) |
| Primary function | maxillary arch expansion |
| Malocclusion target | mild-to-moderate transverse maxillary deficiency; posterior crossbite |
| Inventor | Leone SpA (Florence, Italy) |
| First year | 1970s (Leone ortho products) |
| Period | modern |
| Status | current |
| Uses TADs | no |
The Leone half-screw expander uses a jackscrew from Leone S.p.A. — the Italian orthodontic manufacturer well known for its high-quality expansion screws. "Half screw" refers either to a reduced-dimension screw (shorter expansion range, compact design) or to a half-palate design (one-side expansion). Leone screws are prized for their precision, smooth activation, and consistent force delivery. The appliance is constructed like a standard banded RPE (with palatal acrylic or wire framework), but the screw specifications match the reduced expansion needed — making it appropriate for cases with limited transverse correction needs where a full-range RPE would overshoot.
The Leone jackscrew delivers precise quarter-turn activations; each turn opens the appliance by approximately 0.25 mm (standard) or 0.20 mm (micro-screw variants). The force is transmitted through the palatal framework to the molar bands, opening the mid-palatal suture slowly in growing patients or producing dentoalveolar expansion in older patients. Leone screws are known for their click feedback on activation — an advantage for patient compliance and verification that the screw was turned correctly. The compact half-screw design limits total expansion range, which is appropriate when only 3–6 mm of transverse correction is needed.
Mild-to-moderate maxillary transverse deficiency where a full-range RPE (8–10+ mm range) is unnecessary; crossbite correction requiring 3–6 mm total expansion; cases where the shorter screw dimensions produce a less bulky palatal appliance (improved comfort); practices that prefer Leone hardware quality; phase I treatment in mixed dentition; cases combined with Class III treatment (fan expander for anteriors + Leone screw for posteriors). The Leone brand often signals a preference for European-made precision components.
Same as standard RPE for skeletal vs. dentoalveolar outcomes depending on patient age. Not appropriate for large transverse discrepancies requiring > 6–8 mm correction — a standard full-range RPE is better. Must use the correct Leone screw model — different Leone screws have different expansion ranges and turn ratios; clinical team must know which version they ordered.
element
protocol typically ¼ turn/day (rapid) or every other day (slow)
The Leone screw must be seated correctly — oriented parallel to the occlusal plane, centered in the palate, with the activation key hole visible through the acrylic (not blocked). Acrylic coverage should be broad but not so thick it causes undue tissue pressure. Band fit is critical as always. Key difference from a generic jackscrew expander: the Leone screw itself has higher manufacturing tolerance, so lab work must match — sloppy band adaptation or off-center screw placement undercuts the precision the doctor is paying for. CFL prices range from (standard) to (variant) to (3D version) — the 3D version is a significant jump, suggesting a more complex fabrication or a bonded design.
half-screw.
features.
expander for larger transverse corrections.
selective anterior expansion with fan screw.
Orthodontics](https://www.leone.it/en/products/expansion-screws)
Ortho](https://fivestarortho.com/appliances/expanders/leone/)
Labs](https://odlortho.com/products/rapid-palatal-expander/)
fabrication, business notes.