Upper-molar intrusion using anterior palatal anchorage and the Mousetrap appliance.

antagonists are a common orthodontic problem, especially in adult patients. To facilitate prosthodontic restoration in the mandible, the overerupted molars have to be intruded, which tends to cause the adjacent teeth to extrude when conventional appliances are used. In recent years, temporary anchorage devices (TADs) have allowed orthodontists to overcome these drawbacks while avoiding unesthetic full-appliance therapy.1-6 To avoid tipping the molars that are being intruded, either forces must be applied buccally and lingually or a transpalatal arch (TPA) may be placed. Miniplates inserted in the area of the zygomatic buttress can be employed to anchor a buccal intrusive force for upper molar intrusion,3,4,7-9 but their placement requires a surgical flap and full exposure of the bone. Insertion of larger miniimplants in the zygomatic buttress is a second but less advisable possibility, since coverage of the insertion site by movable mucosa increases the chances of screw failure and soft-tissue irritation.10,11 A third alternative is to insert two miniimplants in the alveolar process.1,2,5,12 Disadvantages of miniscrew placement be tween the roots of the upper molars include the following: • In many cases, there is insufficient space on the buccal side to insert a mini-implant safely between the roots, especially in the region of the upper molars.13-15 Narrower implants carry a higher risk of fracture16 and failure.11,17,18 • The soft tissue is often thicker on the palatal side of the alveolar process,19 necessitating a longer lever arm that increases the likelihood of miniimplant tipping and failure.17 • Contact between a mini-implant and a dental root may cause damage to periodontal structures and possibly lead to failure.20,21 • A molar moved against a mini-implant during intrusion will cease to move, and the root surface may be damaged.22,23 • When a mini-implant is inserted in the posterior area of the upper alveolar process, there is a risk of penetration of the maxillary sinus.24 Considering these problems, it seems preferable to insert the mini-implants away from the roots and teeth to be moved. The anterior palate