Un caso di distalizzazione molare attraverso l’uso delle forze direzionali secondo Tweed-Merrifield

Objectives

To describe a case of severe skeletal and dental malocclusion (Class II) in an actively growing child. The facial disharmony consisted in upper incisor protrusion and a profile characterized by a marked convexity, protrusion of the upper lip, and retrusion of the cutaneous chin. The general objectives were: (1) eliminate the arrest in mandibular growth; (2) exert an orthopedic effect on upper maxilla; (3) correct molar and canine relationships; and (4) improve the facial profile.

Materials and methods

Given the child's age, an excellent mandibular response could still be expected. The parents were informed that the boy's cooperation was essential for the success of the treatment. Treatment consisted in: (1) application to the upper arch of a standard edgewise multibracket appliance (0.021 x 0.028) based on the Tweed-Merrifield Directional Force System; (2) orthopedic treatment of the upper maxilla involving application of high extraoral traction (HpHg) (arch 0.018 x 0.025); (3) evaluation of results achieved with repeat radiography; (4) application of an appliance to the lower arch; (5) continuation of therapy to achieve correct dental relationships (arch 0.019 x 0,025). Use of high extraoral traction (HpHg), Class II elastic bands, and intermaxillary elastics; (6) removal of the appliance and application of an upper Hawley appliance and lower retainer 3/3.

Results and conclusions

The final results were very good in terms of esthetics (occlusal and skeletal). Thanks to the child's full cooperation, both problems were fully resolved with only 29 months of active correction and 12 months’ use of a removable night-time retainer.