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ORTHO TRIBUNE | MAy 2010 Trends 5 lead to false-negative or false- positive results (Figs. 2a–c). Therefore, the placement of a miniscrew should always be based on the clinical findings. If a miniscrew is to be inserted into an area in which there is no risk of damage to roots, nerves or blood vessels (e.g. into the palate just behind the transverse line linking the two canines), the position of the screw may be freely chosen (Figs. 3a–c). Anesthetic During the interradicular insertion of a miniscrew, the sensitivity of the periodontal tissue of the adjoining teeth should be retained. For this reason, the following two proce- dures are recommended: a) a low-dose injection of about 0.5 ml anesthetic (Figs. 4a, b); and AD Pre-operative planning and preparation: • planning documentation (X-ray, situational models); • marking of the muco-gingival line and tooth axes on the model, determining the site of insertion; and • sterilization of the instruments and preparation of the work- station. Anesthetic and assessment of the insertion site: • anesthetic; • use of X-ray aids; and • control image. Selection of the screw: • measuring of the thickness of the mucous membrane (optional); • determination of the length; and • determination of the type of screw. Transgingival penetration: • excision of the mucous mem- brane or perforation with the screw. Preparation of the bone site: • optional marking of the bone; and • perforation of the cortical bone or deep pilot drilling, depend- ing on the type of screw. Insertion of the miniscrew: • manually or by machine. Start of orthodontic measures: • attaching and fixing of the link- ing elements. Post-operative care: • notes on care and behaviour; and • check-up dates. Removal of the miniscrew: • removal of the linking ele- ments; and • removal of the miniscrew. Figs. 8a, 8b: Pre-drill with a 4 mm long blade and limit stop: Drill (FORESTADENT) and tomas-drill SD (DENTAURUM). Figs. 7a, 7b: Diagrams showing the thread mechanisms: self-cutting and self-tapping. Fig. 7a Fig. 7b Fig. 8a Fig. 8b Checklist for insertion b) the induction of superficial anes- thesia of the mucous membrane at the insertion site, for which a topical anesthetic gel is suitable (Figs. 5a, b). No general anes- thetic is ever required for this procedure. g OT page 6