Anchorage, Skeletal Anchorage and Temporary Anchorage Devices
Anchorage, Skeletal Anchorage and Temporary Anchorage Devices tests how resistance to unwanted tooth movement is classified, obtained, and managed. It includes miniscrews, palatal implants, and miniplates.
Core rules
- Anchorage can be classified as intraoral or extraoral, and as primary or secondary. Maximum anchorage means little or no planned anterior retraction; moderate anchorage allows some; minimum anchorage permits substantial reciprocal movement.
- Sources of anchorage include teeth, the palate, the occiput, and skeletal devices. Cervical or occipital headgear can reinforce posterior anchorage but depends on compliance.
- Temporary anchorage devices include miniscrews, palatal implants, and miniplates. Miniscrews are loaded early, often with light force, and can fail if placed in poor bone, near roots, or with excessive force.
- Safe placement requires radiographs or CBCT, knowledge of root positions, and avoidance of nerves, sinus, and vessels. Common sites include the buccal alveolus between roots, the palate, and the retromolar region.
- Skeletal anchorage enables en masse retraction, molar distalization, intrusion, and asymmetric movement.
Worked example
A patient with maxillary protrusion needs maximum retraction after extracting 14 and 24. Reasoning: miniscrews placed between the second premolar and first molar roots can provide indirect or direct anchorage. Apply light continuous force for en masse retraction and monitor root proximity. Without skeletal anchorage, posterior teeth would move mesially and reduce retraction.
Traps
- Placing a miniscrew without checking root proximity.
- Loading a TAD with excessive force or immediately in poor bone.
- Confusing maximum anchorage with routine reciprocal mechanics.
- Forgetting that miniscrews can fail and need a backup plan.