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Trends ORTHO TRIBUNE | MAy 20104 successful treatment with mini- screws. Such planning includes a comprehensive anamnesis and an accurate assessment of the findings. It is essential that the treatment be thoroughly explained to the patient. Proper hygiene must be ensured throughout the entire operation. Both the chair and the treatment process must be prepared with this in mind. During the insertion of a mini- screw, adherence to all hygiene measures required for an invasive procedure, such as a sterile work environment and gloves, must be ensured. All instruments required for insertion must be checked for completeness, functionality and ste- rility. The patient may rinse with a dis- infectant solution, or a suitable dis- infectant can be locally applied. The patient should then be positioned to ensure a clear view of the operation- al area and ergonomically facilitate insertion for the treating clincian. Pre-operative planning To function correctly, a miniscrew requires firm anchorage in the bone (primary stability) and the posi- tioning of its head in the denser gingival tissue (gingiva alveolaris). The selection of the insertion site must take clinical and para-clinical findings into account (X-ray image, model), as well as the goal of the treatment and the resulting orth- odontic appliance. For interradicular inser- tion, a bone thickness of at least 0.5 mm around the miniscrew is required. This means that for a miniscrew with an — for many reasons — optimal diameter of 1.6 mm, the roots must be at least 2.6 mm from each other. Thus, the bone status and the longitudinal axis of the insertion site must be carefully evaluated. Basic information regarding this is obtained by carrying out mea- surements on the model. It often helps to mark the vertical axis of the teeth and the progression of the muco-gingival line on the model, based on the clinical and radiologi- cal findings. This will allow for an improved assessment of the spatial circumstances in combination with the X-ray image. To assist the accurate determina- tion of the insertion site, X-ray aids (Fig. 1) are available. Although their use facilitates the selection of the insertion site, they cannot replace other diagnostic measures. This is because, depending on the positioning of the X-ray tube, object, film, and/or sensor, all types of X-ray devices and images may yield some optical distortion. Interpretation of images can thus Figs. 2a–c: The top image shows the initial situation. An X-ray pin was inserted into the first and second quadrants of the upper jaw (in the 6–5 region) to check the bone site, followed by the miniscrew. Both screws were inserted in a manner that is clinically safe, but the X-ray images show damage to the adjoining root in the right-hand quadrant, indicating a false-positive initial interpretation of the situation. Figs. 3a–c: The clinical image shows two miniscrews inserted into the palate in the safe zone to the distal side of the transversal line linking the two canines. The FRS and the PA image confirm the bone support in the insertion region. Figs. 4a, 4b: Injection pen with needle and anesthetic cartridge and injection of anesthetic. Figs. 5a, 5b: Superficial anesthetic device in pen form with cartridge, and application of superficial anesthetic. Fig. 6: Measuring of the thickness of the mucous membrane in the direction of insertion. (Photo/Dr. Pohl) Fig. 1: X-ray positioning aid (X-ray pin, FORESTADENT) shown in situ in relation to the adjoining tooth axes. f OT page 1 Fig. 2a Fig. 3a Fig. 4a Fig. 5a Fig. 5b Fig. 4b Fig. 3b Fig. 3c Fig. 2b Fig. 2c