38
Removable appliances
Table 38.1Commonly used active components of removable appliances and their uses
| Active components | Fabrication (ss, stainless steel wire) | Use |
| Labial movement Double cantilever spring (Z-spring) |
0.5–0.6 mm diameter ss | Proclination of 1 or 2 incisors (good range) (Activate by pulling away from baseplate at 45°) |
| T-spring | 0.5–0.6 mm diameter ss | Proclination of an incisor/premolar/molar (poor range) (Activate by pulling away from baseplate at 45°) |
| Recurved spring | 0.8 mm diameter ss | Proclination of all four incisors |
| Cross-over wires | 0.7–03 mm diameter ss | Proclination of all four incisors |
| Screws | – | Proclination of multiple incisors where retention poor |
| Palatal movement Roberts’ retractor |
0.5 mm diameter ss (sleeved) | Retraction of prolined and spaced maxillary incisors |
| Buccal canine retractor | 0.5 mm (sleeved) or 0.7 mm diameter ss (unsleeved) | Palatal and distal movement of mesially angulated canines |
| Elastics | Different diameters available | Force dependent on the root surface area of teeth to be moved |
| Distal movement Palatal finger spring |
0.5–0.7 mm diameter ss (guarded) | Distal movement of canines, premolars and molars |
| Headgear | – | Distal movement of molars, J-hook headgear for incisor retraction |
| Expansion Screw |
– | Correction of buccal crossbites |
| Coffin spring | 1.25 mm diameter ss | Buccal crossbite correction |
| Rotation Whip spring |
0.5 mm diameter ss | Correction of mild rotations |
| Extrusion and Intrusion Elastics |
Different diameters available | Force dependent on the root surface area of teeth to be moved |
Figure 38.1 (A) Examples of active removable appliance components: (i) Z-spring (arrow) and T-spring, (ii) recurved spring, (iii) cross-over wires, (iv) Roberts retractor, (v) buccal canine retractor, (vi) elastics, (vii) palatal finger spring for distal molar movement and (viii) midline expansion screw. (B) Examples of retentive removable appliance components: (i) Adams clasp, (ii) Southend clasp, (iii) C(ircumferential)-clasp, (iv) ball ended clasps and (v) labial bow.
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