Enamelin maps to human chromosome 4q21 within the autosomal dominant amelogenesis imperfecta locus

Amelogenesis imperfecta is a group of hereditary enamel defects. Of the autosomal dominant forms, only the local hypoplastic type has been mapped to human chromosome 4q 13-4q21. Enamelin is a large enamel matrix protein secreted by ameloblasts. The purpose of this study was to determine the human chromosomal localization of enamelin to establish an association with various forms of amelogenesis imperfecta. Chromosomal mapping was performed by polymerase chain reaction (PCR) amplification using somatic hybrid and deletion/derivation cell line panels with an enamelin primer set based on 100% conserved regions between pig and mouse cDNAs. Sequence-tagged site content mapping using eight markers within the critical local hypoplastic amelogenesis imperfecta region was then performed using an isolated human enamelin genomic BAC clone. The human enamelin amplicon was confirmed by DNA sequence analysis, revealing 81% and 73% identity to pig and mouse cDNAs, respectively. PCR amplification using a somatic cell hybrid panel placed enamelin on chromosome 4 with analysis of a regional chromosome 4 mapping panel refining the localization to 4q 13.1-q21.23. An identified human enamelin BAC genomic clone was shown to contain markers D4S2604 and D4S2670, as well as the first exon of the human ameloblastin gene, placing enamelin in the critical amelogenesis imperfecta locus between markers HIS1 and D4S2604 at 4q21. Our results suggest that enamelin is a strong candidate gene for this disease. Furthermore, human 4q21 may contain a second cluster of enamel matrix genes located proximally to the identified cluster of dentin and bone genes.     

Odontogenic ghost cell carcinoma: a case report with reference to the relation between apoptosis and ghost cells

The neoplastic variant of calcifying odontogenic cyst has various designations, and its malignant counterpart has been reported as aggressive epithelial odontogenic ghost cell tumor or odontogenic ghost cell carcinoma. We present a case of odontogenic ghost cell carcinoma with reference to the relation between the ghost cells and apoptosis. A 33-year-old man complained of a mandibular mass. The mass occupied the entire right side of the mandible with destruction of both buccal and lingual bone. The mass also infiltrated into submandibular and sublingual spaces. Histologically, the mass was composed of a solid proliferation of hyperchromatic and pleomorphic epithelial cells with abnormal mitoses. Islands of ghost cells were frequently admixed with nucleated cells, and there were foci of ameloblastic differentiation. Immunohistochemical stains for cytokeratins, involucrin, and apoptosis-related proteins such as Bcl-2, Bcl-X(L), and Bax were done. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) assay was also performed. The nucleated cells adjacent to the ghost cells expressed cytokeratins and involucrin, but the ghost cells had no reaction. Bcl-2 was negative. Both Bcl-X(L) and Bax were demonstrated in the nucleated cells adjacent to the ghost cells. The ghost cells exhibited Bax protein. Some nucleated cells adjacent to the ghost cells were positive with TUNEL assay. The above results indicate that ghost cells undergo abnormal terminal differentiation as an apoptotic process.     

Giant cell tumour of hyoid bone: case report

Giant cell tumours of bones are uncommon and are usually found in the epiphyses of long bones. They are rare in flat bones (<10%). The tumour has to our knowledge never been described in the hyoid bone, although 18 cases have been reported in the cartilagenous laryngeal skeleton. We report a giant cell tumour of the hyoid bone in a 45-year-old man, which we excised along with the left half of the hyoid bone. It recurred locally one year later and was cured by excision and split course radiotherapy. The patient is disease-free after 30 months of follow-up.     

Craniofacial distraction osteogenesis en bloc

Bone distraction of the superior and medial thirds of the craniofacial skeleton en bloc, avoiding a frontal craniectomy is presented. We applied this procedure in eight patients who were more than 5 years old with different types of craniofacial synostosis and who had not received previous treatment, and with a normal frontal shape. During monobloc advancement, major complications were encountered in older patients, especially the impossibility of the brain to expand rapidly to fill the retrofrontal dead space. Distraction osteogenesis of the craniofacial skeleton en bloc (without craniectomy) is feasible. Miniplates and screws are avoided as well as the possibility of frontal relapse or fractures of the frontozygomatic region. The patients did not need skull vault remodeling, except for a small cranioplasty at the bregma zone. The results obtained were satisfactory and stable at the time. This procedure avoids any kind of osteosynthesis, there is no extradural dead space, the operative time is brief, and blood loss is minimal. The inconvenience is the necessity of a second operation to remove the distractor.     

Soft tissue surgery in the oral and maxillofacial region

The practice of dentistry is most often perceived as the treatment of the hard tissues of the oral region, specifically the teeth and jaws. However, there are many disorders and conditions involving surgical treatment of the soft tissues that extend to the adjacent and associated structures of the oral and maxillofacial surgery region.     

Orbital infection arising from a primary tooth: a case report

Odontogenic infections may spread to the orbit by one or more of several paths. Such extension is potentially dangerous and may lead to loss of vision. A case of infection from a primary tooth, which extended to the retrobulbar area is presented in this report. Treatment included surgical drainage of the resulting subperiosteal orbital abscess through a Caldwell-Luc approach as well as aggressive antibiotic therapy. The importance of early suspicion of this entity and its potential sequelae are discussed.