22 trends & applications DeNtal tribuNe | January-March, 2010 or functional reasons; a short-term treatment or partial treatment is required that does not involve correction and realignment of the basic dental arch; asymmetrical treatments are associated with the risk of midline displacement and the possibility of compensatory extraction; or a suitable dental baseline situation is to be created for pre-prosthetic treatments. It is important to note that in cases in which space closure treatment is proposed, it must be ensured that the patient is aware of not only the costs and risks of the treatment, but also markedly reduced. 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) Figs. 2a–d: Distalisation of the upper laterals. Miniscrews were inserted in the paramedian region (OrthoEasy, FORESTADENT) (a). OrthoEasy with attached laboratory abutments (b). The Frog Appliance was lashed to the laboratory abutments (c). Lateral X-ray showing the ideal positioning of miniscrews, laboratory abutments and Frog Appliance (d). Miniscrews—a focal point in practice Six-part series by Dr. Björn Ludwig, Dr. Bettina Glasl, Dr. Thomas Lietz & Prof. Jörg A. Lisson—Part III Clinical examples (1) Horizontal tooth displacement Lack of space is one of the main reasons for the oblique positioning of teeth. One way to solve this problem is to create the necessary space. Conversely, premature loss of teeth or anatomical abnormalities may result in gaps that require modification for various reasons. For the correction of horizontal tooth displacement, miniscrews can be used, as these produce no undesirable reactive effects. Distalisation The first case (Figs. 1a–c) presented involves a frequently encountered problem: the patient’s molars had migrated in a mesial direction. This resulted in a marked loss of space in the region of the canines. The two treatment options in such a case are extraction or distalisation. In this case, distalisation was a viable option and extraction was unnecessary. Conventional techniques for distalisation (apart from the use of headgear) require support from other groups of teeth. Creating anchorage in this way has negative reactive effects. In the example under consideration, it is highly probable that protrusion of the anterior teeth for would have resulted, Mesialisation One of the most problematic areas of orthodontic therapy is the correction of the anterior displacement of teeth, and particularly of jaw segments. It Miniscrews can be inserted in the vestibular and—as in this example—palatinal areas. Vestibular insertion of a miniscrew (e.g. between the premolars) is always associated with the miniscrew’s eventual interference with tooth migration. When this occurs, the miniscrew must be extracted and a conventional form of anchorage/blocking (e.g. a ligature) must then be used. In this case, the presence of the primary molars represented a contraindication for insertion on the vestibular side of the premolar region. The paramedian insertion of two miniscrews has several advantages. Firstly, the miniscrews provide a very solid basis for anchorage of the distalisation appliance. Secondly, they will never impede the movement of the lateral teeth. Even after could seem that the availability of miniscrews means that conventional appliances no longer need to be used at all. However, depending on the baseline situation and the nature of the required correction, the use of a combination of devices and appliances is recommended. This is often advisable and may even be necessary for biomechanical reasons, such as in a Class III situation. In the case shown in Figures 3a to c, forced transverse expansion of the palatine suture was used in combination with mesial traction, applied by mean of a Delaire facial mask. The support provided by two miniscrews inserted in the paramedian region redirected the forces of sagittal and transverse movements almost entirely onto the bones. Dental side effects were been should a conventional method distalisation have employed. Such negative results can be avoided by the use of miniscrews. One disadvantage of the coupling necessary between the Walde Frog Appliance used (FORESTADENT) and the miniscrews (see Figs. 1a–c) is that cleaning becomes difficult. As large areas of the mucous membrane are covered, there is the risk of the development of peri-mucositis. If this develops further into peri-implantitis, premature loss of the miniscrews could result. A possible future alternative could be the use of ‘laboratory abutments’ (Figs. 2a–d), which contain no plastics and can be used to couple the appliance with the miniscrews entirely hygienically. Space closure Owing to the availability of miniscrews, new therapeutic techniques can now be used, particularly for the management of the partially edentulous situation that obviates the need for compensatory extractions and the problem of the loss of stability of the units used for anchorage support. It is here that the effect of Newton’s Third Law is particularly apparent, and the 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 Figs. 1a–c: Distalisation of the upper molars. Mesial positioning of teeth 16 and 26, showing clear displacement of the canines (a). Walde Frog Appliance (FORESTADENT) anchored to two miniscrews (b). Distalisation by approx. 6 mm after three months’ treatment, providing sufficient space for the correct repositioning of the canines (c). successful molar distalisation, they can be used to stabilise the situation achieved for the remainder of the treatment. Thirdly, there is no risk of damaging other teeth because of an unfavourable spatial situation and/or incorrect insertion. Orthodontic space closure is frequently indicated if there is a gap in the anterior row of teeth, particularly in the region of the lateral incisors. The undesirable effects of conventional therapeutic techniques are the displacement of the midline and/ or negative inclination of the anterior teeth. If miniscrews are used for the stabilisation 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 (19 x 25) attached to two miniscrews inserted in the interception of the opposing forces is a major consideration within the therapeutic strategy. The orthopaedic closure of dental spaces using miniscrews is highly recommended if: Figs. 3a–c: Mesialisation of the upper molars. Miniscrews inserted in the paramedian region with laboratory abutments (FORESTADENT) and transverse screw with hook for a Delaire facial mask (a). Status after transverse expansion and formation of a median diastema (b). Extra-oral view of the appliance with a Delaire mask (c). Figs. 4a–c: Space closure in the region of the upper anterior teeth. Diagram showing the anchorage principle (a). Baseline situation: The central frontal teeth were held in place using a steel arch (19 x 25) fixed to a miniscrew with additional frontal dental torque (b). After nine months the anchorage is stable (c). 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 distalise the canine further (c).