## 7 Discussion  
Skeletally anchored assisting fixed functional appliances such as the Forsus TM Fatigue Resistant Device and the Herbst appliance have been shown to be effective in improving skeletal form [12; 13; 15; 16; 17]. Other studies have proposed a four miniscrews approach to further improve the skeletal result of fixed functional appliances [14] with favorable results. In this case, we described the Herbst treatment with four miniscrews to obtain an im-proved skeletal correction for crowding and overjet with minimum anchorage loss. Conversely to the buccal miniscrew placement as other authors reported, the upper miniscrews were placed in the anterior area of the palate, allowing different advantages: easier insertion, simultaneous use for hybrid expander, lower risks roots lesions, upper teeth free to move; additionally from a biomechanics point of view, this anchorage allowed the following results: reducing upper molar distalization and intrusion effect of the Herbst, reduction of the upper incisor palatal inclination, maxillary expansion with noteworthy skeletal component. The four miniscrews Herbst treatment finally resulted in a greater skeletal effect and a better control of maxillary and mandibular incisor position and maxillary molar dis-talization (Figure 10). A standard Herbst appliance therapy generally obtained a skeletal correction up to 65% of the class II relationships [18; 19; 20; 21; 22; 23]. [PERSON] described other options to reduce the effect of lower incisors inclinations such the premolar anchorage, premolar-molar anchorage, Pelott anchorage, labial lingual anchorage and class III elastics (150 gr), nevertheless all the systems produced an incisors proclination between 3.1 and 12.1\({}^{\circ}\) post Herbst treatment. [PERSON] et al. evaluated the effectiveness of Herbst treatment with an acrylic splint Herbst appliance adding miniscrews in the lower arch with two types of ligations; they  
Figure 10: Biomechanics diagram. Figure 9: Superimpositions at T0 (start of the treatment) and at T1 (Post-Herbst). showed that the skeletal anchorage reduced mandibular incisors flaring and the elastic chain increased the orthopedic effect of Herbst treatment. [PERSON] et al. assessed whether mandibular anchorage loss during treatment with Herbst/multibracket (MB) appliances can be prevented, using inter-radicular miniscrew anchorage. They showed that this anchorage did reduce proclamation of the lower labial segment to a small extent. The authors found statistically significant differences in anchorage preservation between the study and control groups, even if they were small and were unlikely to be of clinical relevance. In this case, the lower incisors showed a final proclamation of \(1.0^{\circ}\) after the comprehensive therapy; these results are similar to those previously published using skeletal anchorage reinforcement. The upper incisors were slightly retroclined, avoiding naso-labial angle reduction and simultaneously allowing a crowding solution; these results may be addressed by the Hybrid Expander, which allowed a significant amount of skeletal expansion in the upper arch and consequently a significant arch length increase. Miniscrews in the anterior area of the palate also had a key role on the upper first molars avoiding distal and intrusive movement. The success of this approach is deeply related to the miniscrew stability, which, in effect, was successful for both arches. The literature reported skeletal anchorage failure in the lower arch between 17.5 and 30% with Herbst-like appliances, with a higher success rate for the palatal insertion site [23; 24; 25]. The miniscrews success rate could represent a considerable limit, mainly in the lower arch, where the success rate is lower than the palatal area. From a clinical perspective, a lower miniscrew failure could be solved by inserting a new TAD into another position, thus allowing completion of the therapy; nevertheless, this would add more costs and possible patient-related concerns.