Amelogenesis imperfecta.

Amelogenesis imperfecta (AI) represents a group of developmental conditions, genomic in origin, which affect the structure and clinical appearance of enamel of all or nearly all the teeth in a more or less equal manner, and which may be associated with morphologic or biochemical changes elsewhere in the body. The prevalence varies from 1:700 to 1:14,000, according to the populations studied. The enamel may be hypoplastic, hypomineralised or both and teeth affected may be discoloured, sensitive or prone to disintegration. AI exists in isolation or associated with other abnormalities in syndromes. It may show autosomal dominant, autosomal recessive, sex-linked and sporadic inheritance patterns. In families with an X-linked form it has been shown that the disorder may result from mutations in the amelogenin gene, AMELX. The enamelin gene, ENAM, is implicated in the pathogenesis of the dominant forms of AI. Autosomal recessive AI has been reported in families with known consanguinity. Diagnosis is based on the family history, pedigree plotting and meticulous clinical observation. Genetic diagnosis is presently only a research tool. The condition presents problems of socialisation, function and discomfort but may be managed by early vigorous intervention, both preventively and restoratively, with treatment continued throughout childhood and into adult life. In infancy, the primary dentition may be protected by the use of preformed metal crowns on posterior teeth. The longer-term care involves either crowns or, more frequently these days, adhesive, plastic restorations.

Long-term outcome of skull base surgery with microvascular reconstruction for malignant disease.

BACKGROUND: Successful resection of malignant skull base disease depends implicitly on the ability to reconstruct the resulting defects in the craniovisceral diaphragm, to support neural structures, and to prevent ascending intracranial infections. Microsurgery reliably achieves these objectives and has increased the scope of curative oncologic surgery. The authors assessed the reconstructive results and the long-term oncologic outcome of patients having skull base surgery with free tissue transfer. METHODS: A retrospective review of cases between 1989 and 2001 was undertaken. Demographics, histology, surgical management, complications, locoregional control, and survival were analyzed. RESULTS: Predominantly male patients (n = 53; 62 percent) with an average age of 60 years had microvascular reconstruction following oncologic surgery. There was a preponderance of cutaneous malignancies (56 percent), and most lesions involved the anterior skull base (53 percent). Tumors were mostly resected with a combined intracranial or extracranial approach, and reconstruction was undertaken with radial forearm, rectus abdominis, or latissimus dorsi flaps with 94 percent success. Complications occurred in 23 percent of patients, and no specific risk factors for developing intracranial complications were identified. Specifically, extensive reconstructions did not increase the complication rate. The 5-year locoregional control and survival rates were 74 percent and 60 percent, respectively. A positive resection margin significantly increased the risk of locoregional recurrence and worsened disease-specific survival on Cox regression. Survival was also influenced by grade of malignancy. CONCLUSIONS: Microsurgery is highly reliable for reconstructing defects resulting from oncologic resections of the cranial base. It can and should be undertaken using a small number of highly dependable flaps.

A study of the prescription of radiographs for children by a group of general dental practitioners in the South West of England.

OBJECTIVE: This study aimed to assess the familiarity of general dental practitioners (GDPs) in the South West of England with the guidelines in the first edition of the then Faculty of General Dental Practitioners (UK) "good practice guidelines" publication Selection Criteria for Dental Radiography (henceforth referred to as "the guidelines") by studying the prescription of radiographs for children in two case scenarios. METHOD: A single mailshot of questionnaires containing questions relating to the guidelines and the two case scenarios was sent to 136 GDPs in the South West of England. Their recommendations for the prescription of radiographs for the children in the two scenarios were then compared with the guidelines. RESULTS: There was a 60% response rate. Of the respondents, 48% reported that they had access to the guidelines. Of those who responded to the question, 66% said that they found the guidelines easy to use. Seventy per cent of respondents reported that they preferred the concept of guidelines to that of protocols. The results from the case scenarios revealed an under-prescription of radiographs for patients presenting with developmental problems or trauma when compared to the recommendations in the guidelines. There was good correlation for the prescription of radiographs for caries but little consensus on radiographic review times. CONCLUSIONS: The study highlighted (a) areas within the guidelines that require further clarification and research and (b) that in the group studied half did not have access to the guidelines.

A case study of hemispatial neglect using finite element analysis and positron emission tomography.

BACKGROUND: The authors present a patient who developed transient hemispatial neglect following surgical drainage of a large right frontotemporal arachnoid cyst. As symptoms evolved in parallel with brain shift over the subsequent months, the authors hypothesized that the disorder was associated with the appearance of mechanical stresses in the cerebral mantle. METHODS: To map tissue stress at the various stages of deformation, a finite element computer simulation was conducted on the basis of computed tomography scans of the patient. RESULTS: The authors' results demonstrate substantial shear and compressive stress concentrations in the parietal lobe, a region commonly associated with neglect, and where positron emission tomography confirmed hypoperfusion in this patient. Treatment with combined ventricular-peritoneal and cystoperitoneal shunts was accompanied by clinical recovery and improvement of right parietal lobe cerebral blood flow. CONCLUSIONS: The authors conclude that brain deformation was a contributing factor in the reversible neglect syndrome by compromising the normal flow of blood and/or the deactivation of subcortical circuits of the parietal lobe.