Metastatic Pleomorphic Adenoma in the infratemporal fossa and neck following total parotidectomy after 30 years.

Metastasising pleomorphic adenoma is rare and may occur years after surgical excision of a pleomorphic adenoma (PA). We present a 61-year-old woman with a right infratemporal PA with metastases to the cervical lymph nodes after 30 years following a total parotidectomy. She was treated successfully with a resection of the tumour with combined neck and mandibulotomy approach along with postoperative radiotherapy given subsequently.

ViPAR: a software platform for the Virtual Pooling and Analysis of Research Data.

BACKGROUND: Research studies exploring the determinants of disease require sufficient statistical power to detect meaningful effects. Sample size is often increased through centralized pooling of disparately located datasets, though ethical, privacy and data ownership issues can often hamper this process. Methods that facilitate the sharing of research data that are sympathetic with these issues and which allow flexible and detailed statistical analyses are therefore in critical need. We have created a software platform for the Virtual Pooling and Analysis of Research data (ViPAR), which employs free and open source methods to provide researchers with a web-based platform to analyse datasets housed in disparate locations. METHODS: Database federation permits controlled access to remotely located datasets from a central location. The Secure Shell protocol allows data to be securely exchanged between devices over an insecure network. ViPAR combines these free technologies into a solution that facilitates 'virtual pooling' where data can be temporarily pooled into computer memory and made available for analysis without the need for permanent central storage. RESULTS: Within the ViPAR infrastructure, remote sites manage their own harmonized research dataset in a database hosted at their site, while a central server hosts the data federation component and a secure analysis portal. When an analysis is initiated, requested data are retrieved from each remote site and virtually pooled at the central site. The data are then analysed by statistical software and, on completion, results of the analysis are returned to the user and the virtually pooled data are removed from memory. CONCLUSIONS: ViPAR is a secure, flexible and powerful analysis platform built on open source technology that is currently in use by large international consortia, and is made publicly available at [http://bioinformatics.childhealthresearch.org.au/software/vipar/].

Senior dentists' perceptions of dental therapists' roles and education needs in Malaysia.

UNLABELLED: To describe the perceptions of senior dental officers (SDOs) on the roles of dental therapists (DTs) and their education needs in Malaysia. METHODS: A cross-sectional survey was conducted using a self-administered postal questionnaire targeting all 112 SDOs in the Malaysian Ministry of Health. The SDOs were asked about their perceptions of DT's roles in relation to clinical tasks, oral health promotion, administration and the dental team and their perceptions of DT's future education needs. Data were analysed using spss software, version 17 (SPSS Inc., Chicago, IL, USA). RESULTS: The response rate was 60%. A majority of SDOs were women (68%) with a mean age of 44.9 (SD: 8.04). Generally, the majority of SDOs perceived the current roles of DT in non-complex clinical tasks such as examination and diagnosis, preventive treatment, extraction of deciduous teeth and oral health promotion as very important. Fewer than half of SDOs perceived DT's role in the extraction of permanent teeth as important. Most SDOs perceived the need to train DT in 'scaling and polishing for adults' (80.5%), 'delivering inferior alveolar nerve block' (57.3%) and 'pulp therapy' (59.2%). They also had positive perceptions of providing education for DT up to degree level (70.8%). CONCLUSION: This study suggests that Malaysian SDOs have positive perceptions of the current roles of DT and of the expansion of some of their clinical tasks to include broader client groups through further training and education. These findings indicate a need to revise the current curriculum and legislation pertaining to DT's education and scope of practice in Malaysia.

Observation of enhanced transformer ratio in collinear wakefield acceleration.

One approach to future high energy particle accelerators is based on the wakefield principle: a leading high-charge drive bunch is used to excite fields in an accelerating structure or plasma that in turn accelerates a trailing low-charge witness bunch. The transformer ratio R is defined as the ratio of the maximum energy gain of the witness bunch to the maximum energy loss of the drive bunch. In general, R<2 for this configuration. A number of techniques have been proposed to overcome the transformer ratio limitation. We report here the first experimental study of the ramped bunch train (RBT) technique in a dielectric based accelerating structure. A single drive bunch was replaced by two bunches with charge ratio of 1:2.5 and a separation of 10.5 wavelengths of the fundamental mode. An average measured transformer ratio enhancement by a factor of 1.31 over the single drive bunch case was obtained.

Is opportunistic oral cancer screening by dentists feasible? An analysis of the patterns of dental attendance of a nationally representative sample over 10 years.

OBJECTIVES: To assess whether or not opportunistic oral cancer screening by dentists to detect pre-malignant or early cancer lesions is feasible. The objective was to analyse the patterns of dental attendance of a national representative sample over a period of 10 years to ascertain whether individuals at high-risk of oral cancer would be accessible for opportunistic oral cancer screening. METHODS: Secondary analysis of data extracted from the British Household Panel Survey, a national longitudinal survey (n=5547). Analysis to ascertain whether patterns of attendance for dental check-ups for a period of 10 years (1991-2001) were associated with risk factors for oral cancer such as age, sex, education, social class, smoking status and smoking intensity. RESULTS: Males, aged over 40 years, less educated manual workers and smokers were significantly less likely to attend for dental check-ups compared with females and younger, higher educated, higher socio-economic class non-smokers (p < 0.05). Throughout the 10-year period, young people, more than older people, had progressively lower odds ratios of attending. Those with more education used dental services more. Heavy smokers were infrequent attendees. CONCLUSIONS: This study suggests that opportunistic oral cancer screening by dentists is not feasible to include high-risk groups as they are not regular attendees over 10 years. Those who would be screened would be the low-risk groups. However, dentists should continue screening all patients as oral precancers are also found in regular attendees. More should be done to encourage the high-risk groups to visit their dentists.

Observation of multipactor in an alumina-based dielectric-loaded accelerating structure.

We report a new regime of single-surface multipactor that was observed during high-power testing of an 11.424-GHz alumina-based dielectric-loaded accelerating structure. Previous experimental observations of single-surface multipactor on a dielectric occurred in cases for which the rf electric field was tangential and the rf power flow was normal to the dielectric surface (such as on rf windows) and found that the fraction of power absorbed at saturation is approximately 1%, independent of the incident power. In this new regime, in which strong normal and tangential rf electric fields are present and the power flow is parallel to the surface, the fraction of power absorbed at saturation is an increasing function of the incident power, and more than half of the incident power can be absorbed. A simple model is presented to explain the experimental results.

Coherence incoherence and dimensional crossover in layered strongly correlated metals.

The properties of an interacting electron system depend on the electron correlations and the effective dimensionality. For example, Coulomb repulsion between electrons may inhibit, or completely block, conduction by intersite electron hopping, thereby determining whether a material is a metal or an insulator. Furthermore, correlation effects increase as the number of effective dimensions decreases; in three-dimensional systems, the low-energy electronic states behave as quasiparticles, whereas in one-dimensional systems, even weak interactions break the quasiparticles into collective excitations. Dimensionality is particularly important for exotic low-dimensional materials where one- or two-dimensional building blocks are loosely connected into a three-dimensional whole. Here we examine two such layered metallic systems with angle-resolved photoemission spectroscopy and electronic transport measurements, and we find a crossover in the number of effective dimensions from two to three with decreasing temperature. This is apparent from the observation that, in the direction perpendicular to the layers, the materials have an insulating character at high temperatures but become metal-like at low temperatures, whereas transport within the layers remains metallic over the whole temperature range. We propose that this change in effective dimensionality correlates with the presence of coherent quasiparticles within the layers.

Quasiparticle liquid in the highly overdoped Bi(2)Sr(2)CaCu(2)O(8+delta).

Results from the study of a highly overdoped (OD) Bi(2)Sr(2)CaCu(2)O(8+delta) with a T(c) = 51 K using angle-resolved photoemission spectroscopy are presented. We observe a sharp peak in the spectra near ( pi,0) that persists well above T(c), a nodal self-energy which approaches that seen for the Mo(110) surface state, and a more k-independent line shape at the Fermi surface than the lower-doped cuprates. This allows for a realistic comparison of the lifetime values to the experimental resistivity measurements. These observations point to the validity of the quasiparticle picture for the OD even in the normal state.

Doping and temperature dependence of the mass enhancement observed in the cuprate Bi(2)Sr(2)CaCu(2)O(8+delta).

High-resolution photoemission is used to study the electronic structure of the cuprate superconductor, Bi(2)Sr(2)CaCu(2)O(8+delta), as a function of hole doping and temperature. A kink observed in the band dispersion in the nodal line in the superconducting state is associated with coupling to a resonant mode observed in neutron scattering. From the measured real part of the self-energy it is possible to extract a coupling constant which is largest in the underdoped regime, then decreasing continuously into the overdoped regime.

An entropy-coded lattice vector quantizer for transform and subband image coding.

A lattice-based vector quantizer (VQ) and noiseless code are proposed for transform and subband image coding. The quantization is simple to implement, and no vector codebooks need to be stored. The noiseless code enumerates lattice codevectors based on their (weighted) l(1) norm. A software implementation is able to handle lattice codebooks of size 2(256). The image coding performance is shown to be comparable or superior to the best encoding methods reported in the literature.

Levels of serum IgG against Porphyromonas gingivalis in patients with rapidly progressive periodontitis, rheumatoid arthritis and adult periodontitis.

Levels of serum IgG against Porphyromonas gingivalis cell sonicate were determined in patients with rheumatoid arthritis (RA) (n = 25), rapidly progressive periodontitis (RPP)(n = 25) and adult periodontitis (AP)(n = 15) and controls (HP)(n = 10) utilizing the ELISA technique. Comparison between groups showed no significant differences between the HP and RA groups and also between the RPP and AP groups. The increased levels of IgG in the RPP and AP groups were comparable. Significant differences in IgG levels were noted between HP and RPP (p<0.05) and between HP and AP (p<0.01). The differences between RA and RPP and between RA and AP were highly significant (p<0.0001). Thus it was revealed that the serum levels of IgG against P. gingivalis in RPP and AP patients were elevated, whereas the levels in RA patients were comparable to those in controls.

Periodontal status of teeth in contact with denture in removable partial denture wearers.

The aims of the study were to determine the periodontal status of the teeth in contact with removable partial dentures (RPDs) and to compare them with other teeth in the opposing arch not related to any prosthesis. The periodontal status was also assessed in relation to the age of the dentures. Four hundred and twenty-seven patients treated with RPDs from 1981 to 1986 were recalled for examination. Prior to prosthetic treatment they were given periodontal treatment and fillings when required. Initially all were given oral hygiene instructions and motivation. They were reviewed regularly only on a short-term basis. Eighteen patients were suitable for the present study comprising of eight males and 10 females whose mean age was 41 years. The RPDs were in use from 1.5 to 8 years (mean 4.6 years). The following parameters were assessed: Plaque index (P1I), Gingival index (GI), loss of attachment (LA) and tooth mobility. The wearing of RPDs resulted in higher P1I, GI and LA compared to the controls and these differences were statistically significant. There was an increased frequency of higher P1I, GI and LA with the increase in denture age. Minor changes in tooth mobility were observed. It was concluded that the wearing of RPDs was detrimental to periodontal health in patients whose oral hygiene was less than adequate.

Severe progressive periodontal destruction due to radiation tissue injury.

Cancer radiotherapy to the head and neck region results in short- and long-term radiation tissue injuries. Radiation bone injury is a long-term manifestation which could progress to osteoradionecrosis. A case of radiation tissue injury to the periodontium is presented. The possible pathogenesis of these events is described as they relate to the sequential radiographic changes observed over a period of 6 years until the involved teeth were exfoliated. The post-irradiation management of the teeth with advancing periodontal disease in the path of irradiation was by conservative means, including good personal oral hygiene care, scaling and root planing, periodic chlorhexidine irrigation, and topical fluoride application.

Proximal tooth surface quality and periodontal status.

The aim of this study was to determine the periodontal status in relation to the quality of the adjacent proximal tooth surface. The gingival index (GI) and probable pocket depth (PD) were measured in 144 contra-lateral pairs of sound vs. restored and 95 contra-lateral pairs of sound vs. carious surfaces in 124 patients. The restorations studied were silver amalgams and tooth-coloured filling materials, the margins of which were supragingival or level with the gingival margins. The results showed that the GI and PD were greater for both restored and carious tooth surfaces than for the contra-lateral sound surfaces. When all the teeth were grouped together, the differences in the mean values of GI and PD were statistically significant at the P less than or equal to 0.05 level. A comparison between restored and carious (non-paired) tooth surfaces revealed higher mean values of GI and PD for the latter, which were highly significant at the P less than 0.001 level. Thus the present study shows that proximal tooth surface quality influences the health status of the adjacent periodontium.

Early-onset periodontitis: radiographic patterns of alveolar bone loss in 55 cases from a selected Malaysian population.

The objective of this report was to determine the radiographic patterns of alveolar bone loss in early-onset periodontitis (EOP) cases in a selected Malaysian population. The radiographs of 55 cases of EOP patients were examined and the radiographic patterns were classified as follows: Type I: bone destruction on first molars and/or incisors only; Type II: bone destruction on first molars and/or incisors and several additional teeth (less than 14 teeth); Type III: generalized bone destruction (greater than 14 teeth), but with involvement noticeably more extensive on the first molars and/or incisors; Type IV: generalized bone destruction (greater than 14 teeth), but with no more bone loss on the first molars and/or incisors than on other involved teeth. Sex, age, and missing teeth were also recorded. Out of 55 cases, 47 cases, 22 males and 25 females, were classified into the types mentioned above; the remaining 8 cases were excluded due to too many missing teeth. It was found that 7 (14.9%) were Type I; 12 (25.5%) were Type II; 7 (14.9%) were Type III; and 21 (44.7%) were Type IV. There was a predominance of first molar/incisor involvement in Types I, II, and III with the maxillary first molars most frequently involved followed by the mandibular central incisors. Type I occurred in the younger age group and Types II, III, and IV mainly in the older age group. It was concluded that EOP in this patient sample resembled that of western society.

Other dental treatment needs in patients who requested removable partial dentures.

The aims of this study were to determine the dental and periodontal status and the associated treatment needs, other than that for prosthetic care, in patients who requested removable partial dentures. Forty-six patients who had never worn removable partial dentures before were examined for plaque index, tooth status, gingival index, loss of periodontal attachment and tooth mobility. Prior to prosthetic treatment, 15% of the teeth needed conservative treatment and 1% needed extractions. From the periodontal point of view, 65% of the teeth needed some form of related therapy, and 2% of the teeth were at risk of extraction due to advanced mobility.

Cervical cord compression due to ossified posterior longitudinal ligament associated with diffuse idiopathic skeletal hyperostosis.

We describe a case of cervical cord compression due to ossified posterior longitudinal ligament in association with diffuse idiopathic skeletal hyperostosis, in a young female. Characteristic CT findings are described.

Vogt-Koyanagi-Harada syndrome--a case report.

A 30 year old Malay male developed bilateral choroiditis followed by vitiligo, poliosis and canities. CT scan showed nodular thickening of the optic nerves. Characteristic abnormalities were seen in visual and brainstem auditory evoked potentials and fluorescein angiography. These findings were in keeping with the diagnosis of Vogt-Koyanagi-Harada syndrome. Treatment with dexamethasone resulted in complete recovery of vision and partial improvement in skin and hair lesions.