External cervical resorption of a primary canine

Summary. The authors describe the case of a 3-year-old boy who presented with a mobile right maxillary primary canine. Clinical examination revealed this tooth to have an abnormally large crown, which appeared to have sustained a crown–root fracture. Periodontal probing depths of 5 mm were detected around the tooth. Radiographically, there was a marked constriction at the cementoenamel junction with associated alveolar rarefaction. Both upper primary canines were subsequently removed under general anaesthetic and the right canine was subject to histopathological investigation. A diagnosis of external cervical resorption was made. A review of the literature confirmed this to be a very unusual case presentation.     

Missing facial parts computed by a morphable model and transferred directly to a polyamide laser-sintered prosthesis: an innovation study

Mirroring of missing facial parts and rapid prototyping of templates have become widely used in the manufacture of prostheses. However, mirroring is not applicable for central facial defects, and the manufacture of a template still requires labour-intensive transformation into the final facial prosthesis. We have explored innovative techniques to meet these remaining challenges. We used a morphable model of a face for the reconstruction of missing facial parts that did not have mirror images, and skin-coloured polyamide laser sintering for direct manufacture of the prosthesis. From the knowledge gleaned from a data set of 200 coloured, three-dimensional scans, we generated a missing nose that was statistically compatible with the remaining parts of the patient's face. The planned prosthesis was manufactured directly from biocompatible skin-coloured polyamide powder by selective laser sintering, and the prosthesis planning system produced a normal-looking reconstruction. The polyamide will need adjustable colouring, and we must be able to combine it with a self-curing resin to fulfil the requirements of realistic permanent use.     

Foreign body ingestion in dental practice

Most foreign bodies pass through the gastrointestinal tract uneventfully. The majority of the reported literature describes the management of ingested blunt objects. However, ingestion of sharp objects can still occur with a higher rate of perforation corresponding to treatment dilemmas. We report a case of inadvertently ingested sharp foreign body by a special child, which was retrieved by endoscopic guided forceps. Urgent endoscopic assessment and retrieval of recently ingested sharp dental foreign body is indicated and routine use of preventive measures such as rubber dam, gauze throat screens or floss ligatures is suggested.     

CAD/CAM-produced surgical guides: Optimizing the treatment workflow

The increased availability of devices for 3D radiological diagnosis allows the more frequent use of CAD/CAM-produced surgical guides for implant placement. The conventional workflow requires a complex logistic chain which is time-consuming and costly. In a pilot study, the workflow of directly milled surgical guides was evaluated. These surgical guides were designed based on the fusion of an optical impression and the radiological data. The clinical use showed that the surgical guides could be accurately placed on the residual dentition without tipping movements. The conventional surgical guides were used as a control for the manual check of the deviation of the implant axis. The direct transfer of the digital planning data allows the fabrication of surgical guides in an external center without the need of physical transport, which reduces the logistic effort and expense of the central fabrication of surgical guides.     

Aggregatibacter actinomycetemcomitans leukotoxin is post-translationally modified by addition of either saturated or hydroxylated fatty acyl chains

Aggregatibacter actinomycetemcomitans, a common inhabitant of the human upper aerodigestive tract, produces a repeat in toxin (RTX), leukotoxin (LtxA). The LtxA is transcribed as a 114-kDa inactive protoxin with activation being achieved by attachment of short chain fatty acyl groups to internal lysine residues. Methyl esters of LtxA that were isolated from A. actinomycetemcomitans strains JP2 and HK1651 and subjected to gas chromatography/mass spectrometry contained palmitoyl (C16:0, 27-29%) and palmitolyl (C16:1 cis Δ9, 43-44%) fatty acyl groups with smaller quantities of myristic (C14:0, 14%) and stearic (C18:0, 12-14%) fatty acids. Liquid chromatography/mass spectrometry of tryptic peptides from acylated and unacylated recombinant LtxA confirmed that Lys(562) and Lys(687) are the sites of acyl group attachment. During analysis of recombinant LtxA peptides, we observed peptide spectra that were not observed as part of the RTX acylation schemes of either Escherichia coliα-hemolysin or Bordetella pertussis cyclolysin. Mass calculations of these spectra suggested that LtxA was also modified by the addition of monohydroxylated forms of C14 and C16 acyl groups. Multiple reaction monitoring mass spectrometry identified hydroxymyristic and hydroxypalmitic acids in wild-type LtxA methyl esters. Single or tandem replacement of Lys(562) and Lys(687) with Arg blocks acylation, resulting in a >75% decrease in cytotoxicity when compared with wild-type toxin, suggesting that these post-translational modifications are playing a critical role in LtxA-mediated target cell cytotoxicity.     

The expressions of insulin-like growth factors, their receptors, and binding proteins are related to the mechanism regulating masseter muscle mass in the rat

OBJECTIVE: The mechanism regulating skeletal muscle mass is unclear. The purpose of the present study was to investigate the extent to which insulin-like growth factors (IGFs), their receptors (IGFRs), and binding proteins (IGFBPs) are involved in the regulation of skeletal muscle mass. DESIGN: We measured the mRNA expression levels for IGFs, IGFRs, and IGFBPs in the rat masseter muscle hypertrophied by oral administration of clenbuterol for 3 weeks and determined the correlations between the weight of masseter muscle and the mRNA expression levels. RESULTS: The mRNA expression levels for IGF-I and II, IGFR1 and 2, and IGFBP4 and 6 showed clenbuterol-induced elevations and positive correlations with the weight of masseter muscle. That for IGFBP3 only exhibited a clenbuterol-induced decrease and a strong negative correlation with the weight of masseter muscle. The mRNA expression levels for IGFBP2 and 5 showed no significant changes between the control and clenbuterol groups, and no significant correlations. IGFBP1 mRNA was not detectable. CONCLUSION: These results suggest that IGF-I, II, IGFR1 and 2, and IGFBP3, 4 and 6 are related to the mechanism regulating masseter muscle mass in the rat.     

An audit of the UK national cancer referral guidelines for suspected oral mucosal malignancy

BACKGROUND AND OBJECTIVE: This study aimed to assess the effectiveness of the UK National Guidelines for identifying patients with potentially malignant oral disease which were introduced in 2000. DESIGN: Retrospective audit. SETTING: The oral medicine unit in a university teaching hospital in London. METHODS: All new referrals over a one year period were retrospectively reviewed in a departmental audit to evaluate guideline effectiveness. Reasons for referral and final diagnosis were compared in a randomly selected sub-population. RESULTS: Four hundred and eighty-seven of 901 new patients referred were classified as having potentially malignant disease from the referral letter. In a randomly selected subgroup of 241 patients, 18 actually had malignant (8) or dysplastic lesions (10). Of 75 patients referred with a persistent oral ulcer, only nine were actually malignant or dysplastic. Eight of 116 patients referred with a white patch and none with red patches were found to have dysplastic or malignant lesions. The criteria failed to identify three carcinomas and two severely dysplastic lesions (15% of the malignant or dysplastic lesions). All of the latter had been referred by primary care physicians with orofacial pain of unknown cause. CONCLUSIONS: UK National Guidelines discriminate poorly between potentially malignant and other oral mucosal disease.     

An object-relational model for structured representation of medical knowledge

Domain specific knowledge is often not static but continuously evolving. This is especially true for the medical domain. Furthermore, the lack of standardized structures for presenting knowledge makes it difficult or often impossible to assess new knowledge in the context of existing knowledge. Possibilities to compare knowledge easily and directly are often not given. It is therefore of utmost importance to create a model that allows for comparability, consistency and quality assurance of medical knowledge in specific work situations. For this purpose, we have designed on object-relational model based on structured knowledge elements that are dynamically reusable by different multi-media-based tools for case-based documentation, disease course simulation, and decision support. With this model, high-level components, such as patient case reports or simulations of the course of a disease, and low-level components (e.g., diagnoses, symptoms or treatments) as well as the relationships between these components are modeled. The resulting schema has been implemented in AMOS II, on object-relational multi-database system supporting different views with regard to search and analysis depending on different work situations.