The validity of a clinical use of interradicular miniscrew anchorage for the distal movement of maxillary molars has been referred to recently in the literature. Yamada et al. [8] concluded that miniscrews placed in the maxillary interradicular space provided successful distal movement of molars without patient cooperation or undesirable side effects. Palatal implants have also been used for molar distalization. Gelgor et al. [9] provided anchorage and indirect distalization with a miniscrew in the palate that connected a transpalatal bar to an upper first premolar on either side. Other authors [10,11] have also used similar systems, with miniscrews supported by auxiliary elements, such as an intraoral distalizer or transpalatal bar, in order to gain direct or indirect anchorage. So, both anchorage and distalization can be obtained by using miniscrews with an auxiliary element [9-12], with successful distalization rates and no loss of anchorage (Figure 1).

Lower molar distalization has also been described in the literature. In 2005, Chung et al. [13] used miniscrews for indirect anchorage in the lower dentition. Two miniscrews were inserted between the upper premolars and molars, and Class III elastics run through them to achieve successful distalization. A further possibility is a mini-implant inserted in the ramus of the mandible (Figure 2) providing direct anchorage for lower dentition distalization with a high rate of success (Figure 3).

Another of the applications of miniscrew appliances seems to be to provide anchorage for midline coordination. In their 2011 study, Yanagita et al. [2] placed a miniscrew in the right buccal area following the closure

of the extraction space in order to correct the maxillary midline. In that case, mandibular molar uprighting was also required. The result was alignment of the dental midline with the facial midline and molar uprighting.

In 2011, Aboul-Ela et al. [14] published a study evaluating treatment using a miniscrew implant to support maxillary canine retraction following extraction of the maxillary first premolars. This study reported no molar anchorage loss during canine retraction, indicating that miniscrew anchorage could be successfully used for this purpose.

Thiruvenkatachari et al. [15] compared and measured the amount of anchorage loss during canine retraction using both miniscrews and conventional molar anchorage. Their results showed no anchorage loss on the miniscrew side and they concluded that miniscrews could be used for canine retraction with a high success rate. Many other authors [16-18] have also published studies on the retraction of anterior teeth using miniscrews. The extraction space was fully utilized during canine retraction with no anchorage loss.

Freudenthaler et al. [19] studied the effectiveness of miniscrews in protracting the lower molars into the extraction socket. Miniscrews 2 mm in diameter were inserted between the second premolars at the level of the apical thirds. Similarly, Kyung et al. [20] reported the case of a patient whose lower first molars had been extracted. The lower second molars were protracted with the aid of miniscrews placed between the premolars. Giancotti et al. [21] also illustrated their clinical experience of an adult patient who was treated by extracting the mandibular first molars and placing miniscrews distal to the second premolars. The result was space closure with no anchorage loss and successful protraction of the second and third molars into the extraction sites.

In 2010, Kocsis et al. [22] published a study evaluating the possible effect of miniscrews in managing impacted upper canines. An intraosseous screw was placed into the premolar-molar interradicular space. A high rate of success was achieved and they concluded that miniscrew anchorage should be borne in mind when planning the extrusion of impacted canines, in line with previous studies [23]. Where there are prosthodontic requirements, miniscrews can also be used to handle canine extrusion. Roth et al. [24] reported a case where incisor and canine extrusion was needed for the future construction of a bridge. The patient’s right incisor was missing and the gingiva at the central incisor and canine had receded by 3 - 4 mm. The miniscrew was placed into the alveolus of the missing upper lateral incisor, and extrusion of central incisor and canine was successfully achieved.

Miniscrews are very useful for the non-surgical management of anterior open bite cases with molar intrusion (Figure 3). A recent 2010 case report [25] described the successful treatment of a severe anterior open bite using miniscrew anchorage. The miniscrews were implanted bilaterally between the second premolar and the first molar, and an intrusion force applied. The results showed that the maxillary molars were intruded and a good occlusion achieved. Another case report [26] from 2009 reported the case of an open bite treated by intruding the molars with four miniscrews placed bilaterally in the interradicular space between both upper and lower posterior teeth. Upper molar intrusion is also illustrated in Figure 3, where anchorage was achieved by inserting two miniscrews mesial and distal to the upper first molar using a closed coil-spring and transpalatal bar.

Overeruption of maxillary molars resulting from the loss of the opposite teeth is frequently seen in clinical practice today. Overeruption interferes with occlusion and creates functional disturbances. In order to restore a proper occlusion, intrusion of overerupted molars is essential. Many studies have been published which have concluded that the miniscrew appliance can be successfully used for molar intrusion. In one recent report [27], the authors described maxillary molar intrusion in order to gain enough prosthetic space for a future implant. Other studies have been published in which overerupted lower and upper molars were intruded with miniscrews [28]. Upper molars can also be intruded with miniscrews on the buccal and palatal sides before commencing the prosthetic restoration of missing teeth [29,30].

Conventionally, a combination of mandibular and maxillary osteotomy has been used to correct both mandibular deviation and canted maxillary occlusal plane. One case, reported by Hashimoto et al. [34], suggested a combination treatment using miniscrews and mandibular osteotomy, and the authors described the functional and morphologic changes achieved using miniscrew anchorage instead of maxillary osteotomy. The canted maxillary occlusal plane was corrected using miniscrew anchorage for intrusion of the maxillary right molars, and the mandibular deviation by mandibular osteotomy. The authors concluded that the combination of miniscrew anchorage and mandibular osteotomy was effective for treating patients with mandibular deviation and canted maxillary occlusal plane. In 2006, DeVincenzo [35] presented another case report about correction of the occlusal plane. The author developed a new appliance, called the vertical adjustable corrector, to treat extreme dolichocephalic malocclusions. Intrusion of posterior or anterior teeth may alter the occlusal plane and their conclusion was that this method represented an alternative to surgery.

Different biomechanics have been reported for molar uprighting. Park et al. [36,37] reported that miniscrews could be used to upright mesially inclined mandibular and maxillary second molars. Elastic thread was needed to achieve the effect, and upright the mesially angulated second molar. In 2011 Yanagita et al. [2] used miniscrew anchorage to upright lower molars and correct severe crowding and a midline deviation. The results were retraction of the mandibular teeth into the extraction socket with absolute anchorage and correction of a Class III malocclusion and dental midline deviation. Giancotti et al. [38] uprighted an impacted mandibular second molar with a closed-coil spring, attached to a miniscrew implanted in the retromolar region. In 2005, Yun et al. [39] described the use of miniscrews to provide indirect anchorage when uprighting two cases of mesially tipped mandibular second molars.