Case report: orofacial characteristics of Hallermann-Streiff Syndrome.

BACKGROUND Hallermann in 1948 and Streiff in 1950 described patients characterised by "bird face", congenital cataract, mandibular hypoplasia, and dental abnormalities. The new syndrome was later defined as Hallermann-Streiff Syndrome (HSS), underlining the differences with regard to Franceschetti's mandibulofacial dysostosis. CASE REPORT Examination of a white male affected by Hallermann-Streiff Syndrome revealed facial characteristics typical of the "bird face" in HSS. The nose appeared thin, sharp and hooked; the prominence of the chin was absent in the lateral view; a marked microstomia was evident as well. Radiographic records showed aplasia of teeth 14, 13, 12, 22, 24, 35, 34, 33, 32, 31, 41, 42, and 43. As for orthodontic diagnosis, the following dentoskeletal features were assessed: skeletal Class II malocclusion, narrow upper arch, bilateral posterior crossbite, and anterior open bite. Lateral cephalogram showed hypoplasia of the mandible, a typical sign of HSS. The mandible revealed a clockwise rotation growth pattern with an opening of the gonial angle, skeletal anterior open bite, and an excessive vertical dimension of the lower third of the face. Radiographs at the age of 13 years showed an anomaly in shape of the lower right first bicuspid, which appeared with a double crown. TREATMENT Orthodontic treatment started at 10 years of age with rapid maxillary expansion in the early stages of the mixed dentition, in order to correct the posterior crossbite due to the narrow maxillary arch. A subsequent phase of the orthodontic therapy consisted of a functional appliance with the goal of maintaining the transverse dimension of the dental arches and of controlling the tongue thrust in the anterior open bite. Surgical and prosthetic interventions were scheduled at completion of growth to solve the skeletal discrepancy and for occlusal rehabilitation. FOLLOW-UP The therapeutic protocol used in the patient presented here was able to reach the orthodontic goals during the developmental ages. Further treatment is planned as there are multiple missing permanent teeth and prosthetic/restorative care is needed until the patient reaches full adulthood.