The pycnodysostosis is a genetically determined, autosomal recessive osteosclerosis, due to deficiency of cathepsin K. It is characterized by short stature, massive skull, hands and feet with short terminal phalanges, dysplastic nails. Oral and maxillofacial manifestations include hypoplasia of the mandible and maxillary sinus, obtuse mandibular gonial angle deciduous teeth and permanent impacts, or malposition, frequent overcrowding, periodontal lesions. Bone sclerosis is already detectable in X-rays during childhood, often present open fontanelles and sutures, wormian bones; frequent pathological fractures. This article presents the case of a male patient, Caucasian, age 9 years and 11 months suffer from pycnodysostosis, mutation of the gene in heterozygotes p.R241X, already followed at the Pediatric Endocrinology Clinic of the Spedali Civili of Brescia. After evaluation at the Department of Maxillofacial Surgery of the Spedali Civili of Brescia, for surgical reasons required a cone beam computed tomography (CBCT) scanner with NewTom 3G, was presented to our observation at the Department of Orthodontics of the Dental Clinic of the University of Brescia. CBCT findings including detailed information about the anatomy of the upper and lower jaw, dental elements, their relationship with the surrounding anatomical structures and the spatial position. The only radiographic examination currently available that obtains 3D images and the volume of the life-size area, without exposing patient to dose of radiation from a classic multi-layer CT is CBCT that, even through the 3D reconstructions with dedicated programs can make a correct diagnosis, prognosis and treatment in patients with maxillofacial dysmorphism. This examination allows to obtain images from around the skull that permit a complete orthodontic diagnosis, not only restricted to the area of surgical interest, taking into account the reports of the dental arches to each other and with surrounding structures.
