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ORTHO TRIBUNE | JUNE & JUly 2010 Trends 5 Space closure Owing to the availability of minis- crews, new therapeutic techniques can now be used, particularly for the management of the partially edentu- lous situation that obviates the need for compensatory extractions and the problem of the loss of stability of the units used for anchorage sup- port. It is here the effect of Newton’s Third Law is particularly apparent, and the interception of the oppos- ing forces is a major consideration within the therapeutic strategy. The orthopedic closure of dental spaces using miniscrews is highly recom- mended if: • there are no alternative, viable conventional methods and/or there is insufficient certainty that these will be effective; • the extensive use of braces is to be avoided for cosmetic or func- tional reasons; • a short-term treatment or par- tial treatment is required that does not involve correction and realignment of the basic dental arch; • asymmetrical treatments are associated with the risk of mid- line displacement and the possi- bility of compensatory extraction; • or a suitable dental baseline situ- ation is to be created for pre- prosthetic treatments. It is important to note that in cases in which space closure treat- ment is proposed, it must be ensured the patient is aware of not only the costs and risks of the treatment, but also of the available alternative options, such as the use of bridges or implants. There are three types of space closure. • Anterior space closure (e.g., in displacement of the lateral incisors). Orthodontic space closure is fre- quently indicated if there is a gap in the anterior row of teeth, par- ticularly in the region of the lateral incisors. The undesirable effects of con- ventional therapeutic techniques are the displacement of the midline and/or negative inclination of the anterior teeth. If miniscrews are used for the stabilization of the median incisors (Figs. 4a–c), such effects can be avoided. A stable, rigid steel arch with a size of at least 0.48 mm by 0.64 mm attached to two minis- crews inserted in the median or paramedian region can be used to stabilize the anterior teeth. Using the standard vestibular mechanical techniques, the gap can be closed without altering the posi- tion of the incisors. • En masse or canine retraction (e.g., where the premolars are miss- ing). Miniscrews can also be used as an aid in this form of treatment (Figs. 5a–c). In contrast with the conventional appliances, there is no loss of anchorage but rather a biomechanical benefit in terms of more favorable direction of forces. If the miniscrew and the fitting for the active element (traction spring or elastic chain) are posi- tioned at the same level as the resis- tance center of the canines, physical AD Figs. 5a–c: Space closure in the region of the upper anterior teeth. En masse retraction with the aid of miniscrews and a Power Arm (FORESTADENT), which has been crimped here (a). Status after extraction of the premolars, showing OrthoEasy miniscrew (b). The Power Arm is used as a sliding mechanism, in order to distalize the canine further (c). g OT page 6 5a 5b 5c