Development of quality measurement instruments for root canal treatment.

AIM: To devise measurement instruments for 'quality' of root canal treatment to assess training and outcome of general dental practitioners working within primary care settings. METHOD: Scoring systems relating to quality of root canal treatment were developed using expert consensus and published literature. Domains scored included the Treatment Process, Quality of the Obturation, Clinical Healing, Radiographic Healing and Tooth Complexity. Scoring systems were applied to 10 clinical cases treated by each dentist at the beginning and 10 cases treated at the end of their clinical training and 135 cases treated after completion of training. The dentists recorded the treatment process and clinical healing in clinical logs. Two examiners independently scored the radiographs after undertaking calibration and training. Inter- and intra-examiner reliability of scoring radiographic outcomes was tested using Cohen's Kappa statistics. RESULTS: An instrument was created with four domains to assess quality (two for process and two for outcome of root canal treatment), and a measure of case complexity. Domains of treatment process (n = 240 teeth), outcome (n = 32 teeth) and complexity (n = 215 teeth) were scored using radiographs. The Kappa scores for intra-examiner reliability between 0.22 and 1, whilst inter-examiner reliability ranged between 0.18 and 0.99. CONCLUSION: Evidence-based scores for assessment of the quality (process and outcome) and complexity (structure) of root canal treatment were devised. They were reliable, provided that clinicians were trained in record keeping and examiners have in depth training and calibration in the use of the instruments.

Regulation of HMG-CoA synthase and HMG-CoA reductase by insulin and epidermal growth factor in HaCaT keratinocytes.

Synthesis of cholesterol, via the isoprenoid/mevalonate pathway, is required for keratinocyte growth and differentiation, and maintenance of the stratum corneum lipid lamellae. 3-hydroxy-3-methylglutaryl coenzyme A synthase catalyzes the first step in isoprenoid/mevalonate synthesis and under some conditions controls the flux into the pathway. We have investigated whether selected growth factors and hormones could increase 3-hydroxy-3-methylglutaryl coenzyme A synthase mRNA in keratinocytes. Northern blotting was used to demonstrate that 10 microg per ml insulin and 0.1 microg per ml epidermal growth factor both increased steady-state levels of 3-hydroxy-3-methylglutaryl coenzyme A synthase mRNA by 2.5 and 6-fold, respectively. Epidermal growth factor and insulin also increased 3-hydroxy-3-methylglutaryl coenzyme A reductase enzyme activity. 3-hydroxy-3-methylglutaryl coenzyme A synthase promoter activity in a luciferase reporter construct was increased 2-fold by insulin and 2.9-fold by epidermal growth factor. When a mutation in the sterol regulatory element was introduced into the 3-hydroxy-3-methylglutaryl coenzyme A synthase promoter, activity was not increased by insulin, but was increased by epidermal growth factor. Mutation of an AP-1 site in the 3-hydroxy-3-methylglutaryl coenzyme A synthase promoter did not affect the increase in activity following treatment with insulin or epidermal growth factor. Therefore, 3-hydroxy-3-methylglutaryl coenzyme A synthase expression in keratinocytes is regulated by insulin and epidermal growth factor by different mechanisms. These results suggest a role for hormones and growth factors in the control of epidermal cholesterol synthesis.

Expression and regulation of mRNA for putative fatty acid transport related proteins and fatty acyl CoA synthase in murine epidermis and cultured human keratinocytes.

The epidermis has a requirement for fatty acids in order to synthesize cellular membranes and the extracellular lipid lamellar membranes in the stratum corneum. Despite high endogenous production of fatty acids the transport of exogenous essential fatty acids into the epidermis is an absolute requirement. Fatty acid uptake by keratinocytes has been shown to be mediated by a transport system. In this study we determined in murine epidermis and human cultured keratinocytes the expression of three putative fatty acid transport related proteins and fatty acyl CoA synthase, an enzyme that facilitates the uptake of fatty acids by promoting their metabolism. In cultured human keratinocytes, mRNA for fatty acid transport protein (FATP), plasma membrane fatty acid binding protein (FABP-pm), and fatty acyl CoA synthase (FACS) were detectable. Differentiation, induced by high calcium, did not affect FATP mRNA levels, but resulted in an approximately 50% increase in FACS mRNA, while decreasing FABP-pm mRNA by 50%. Fatty acid translocase (FAT) mRNA was not detected in cultured human keratinocytes. In murine epidermis, FATP, FABP-pm, FACS, and FAT mRNA were all present. Barrier disruption by either tape stripping or acetone treatment increased FAT mRNA levels by approximately 2-fold without affecting FATP, FABP-pm, or FACS. Occlusion with an impermeable membrane immediately after barrier disruption completely blocked the increase in FAT mRNA levels, indicating that this increase is related to barrier disruption rather than a nonspecific injury effect. In summary, this study demonstrates that several putative fatty acid transport related proteins as well as fatty acyl CoA synthase are expressed in keratinocytes and epidermis, and that the expression of these proteins may be regulated by differentiation and/ or barrier disruption.

Permeability barrier disruption coordinately regulates mRNA levels for key enzymes of cholesterol, fatty acid, and ceramide synthesis in the epidermis.

The extracellular lipids of the stratum corneum, which are comprised mainly of cholesterol, fatty acids, and ceramides, are essential for epidermal permeability barrier function. Moreover, disruption of the permeability barrier results in an increased cholesterol, fatty acid, and ceramide synthesis in the underlying epidermis. This increase in lipid synthesis has been shown previously to be due to increased activities of HMG-CoA reductase, acetyl-CoA carboxylase, fatty acid synthase and serine palmitoyl transferase, key enzymes of cholesterol, fatty acid, and ceramide synthesis, respectively. In the present study, we determined whether the mRNA levels for the key enzymes required for synthesis of these three classes of lipids increase coordinately during barrier recovery. By northern blotting, the steady-state mRNA levels for HMG-CoA reductase, HMG-CoA synthase, farnesyl pyrophosphate synthase, and squalene synthase, key enzymes for cholesterol synthesis, all increased significantly after barrier disruption by either acetone or tape stripping. Additionally, the steady-state mRNA levels of acetyl-CoA carboxylase and fatty acid synthase, required for fatty acid synthesis, as well as serine palmitoyl transferase, the rate-limiting enzyme of de novo ceramide synthesis, also increased. Furthermore, artificial restoration of the permeability barrier by occlusion after barrier disruption prevented the increase in mRNA levels for all of these enzymes, except farnesyl pyrophosphate synthase, indicating a specific link of the increase in mRNA levels to barrier requirements. The parallel increase in epidermal mRNA levels for the enzymes required for cholesterol, fatty acid, and ceramide synthesis may be due to one or more transcription factors that regulate lipid requirements for permeability barrier function in keratinocytes.

A novel electrobiotechnology for the recovery of precious metals from spent automotive catalysts.

Platinum group metals are routinely used in automotive catalysts but recycle technology lags behind demand. There is no available 'dean technology' and leach solutions (e.g. aqua regia) to solubilise the metals from scrap are highly aggressive. A microwave-assisted leaching method was developed which gave 80% metals recovery, with the leach time reduced from 2 h to 15 min using 50% (aq.) diluted aqua regia to give potentially a more biocompatible leachate. Desulfovibrio desulfuricans reduces soluble platinum group metals to cell-bound insoluble base metals (e.g. Pd(II) --> Pd(0)). For use, biofilm was immobilised on a Pd-23% Ag solid alloy membrane which delivered H. to the cells via an electrochemical chamber at the back-side. The biomass-coated Pd-Ag alloy electrode was used in a flow-through reactor for recovery of Pd, Pt and Rh from aqua regia leachates (pH 2.5) of spent automotive catalysts with up to 90% efficiency at a flow residence time of 15 minutes. Free cells did not reduce platinum group metals from the leachates but the electrobioreactor did so using biofilm-cells pre-loaded with Pd(0). Reactors lacking biomass or reactors with heat-killed biofilm removed less platinum group metals, via electrochemically-synthesised H. reductant alone. The use of an active biofilm layer in a flow-through electrobioreactor provides a simple, dean and rapid potential recycle technology.

Case report: aesthetic management of a localised periodontal defect with a gingival veneer prosthesis.

Traditionally acrylic resin gingival veneer prostheses have been used to disguise aesthetic deficiencies of maxillary anterior teeth following successful periodontal therapy and have been retained by engaging horizontal undercuts distal to the canine teeth. They are, however, versatile prostheses with uses in fixed and removable prosthodontics and therapeutic treatment of gingival conditions. In the case presented a small acrylic resin gingival veneer prosthesis retained by a resilient lining material was used to manage a localised periodontal defect of the mandibular central incisor teeth.

An overview of dental care for the young patient: 3. Treatment measures.

In this final part of the series the reasons for providing high-quality restorations for the young patient are considered. For such treatment to be successful it must be underpinned by effective management of the child's behaviour. Appropriate techniques and materials for a range of commonly encountered situations are discussed, with particular emphasis on the restoration of carious teeth.

An overview of dental care for the young patient: 1. Introduction, priorities and disease prevention.

The provision of high-quality dental care for children presents a challenge for the general dental practitioner. The aim must be to ensure that young patients reach adulthood with optimal dental health. This series of three articles takes an overview of good practice in the provision of dental care for children, with emphasis on disease prevention, early diagnosis of dental disease and deformity and appropriate treatment measures. This first paper discusses preventive measures and highlights the need to apply them, particularly for patients at high risk of dental disease or with special needs in relation to dentistry.

Performance of a metal hydride store on the "Ross Barlow" hydrogen powered canal boat.

This project involved the conversion of a British Waterways maintenance craft to a canal boat, powered by a combination of a solid-state hydrogen store, Proton Exchange Membrane (PEM) fuel cell, lead-acid battery pack and a high-efficiency, permanent magnet (NdFeB) electric motor. These replaced the conventional diesel engine thus eliminating water, noise, local and general atmospheric pollution. The "Protium" project applies modern technologies to a traditional mode of transportation. The TiMn2-based metal hydride store exhibited excellent performance as an effective means of storing 4 kg of hydrogen with a suitable desorption flow rate and temperature adequate for the operation of a 1 kW PEM fuel cell in a water-based environment.

A comparison of the fit of spark-eroded titanium copings and cast gold alloy copings.

The fit of spark-eroded titanium and cast gold alloy copings was compared by assessment of retrieved cement film analogues. This technique was chosen for its simplicity, nondestructive nature, and for the information it provided on overall fit. The present study showed that the overall fit of titanium copings was comparable to that of gold copings. In marginal areas, the space between die and coping was found to be larger for spark-eroded than cast copings.

Application of cross-sectional imaging in the differential diagnosis of apical radiolucency.

A case is described in which exact localization of a cystic lesion associated with the apices of the maxillary central incisor teeth was sought to aid diagnosis and presurgical planning. The area was imaged using cross-sectional tomographic slices in the sagittal plane produced by a Scanora multimodal tomographic unit (Orion Corporation Soredex, Helsinki, Finland). The images demonstrated the cystic lesion arising within the incisive canal, conforming a diagnosis of naso-palatine duct cyst. Surgery was therefore performed via a palatal approach giving direct access to the cyst. Histological examination of the enucleated cyst confirmed a nasopalatine duct cyst.

Closed-form approximations to the REML estimator of a variance ratio (or heritability) in a mixed linear model.

In this article, we estimate heritability or intraclass correlation in a mixed linear model having two sources of variation. In most applications, the commonly used restricted maximum likelihood (REML) estimator can only be obtained via an iterative approach. In some cases, the algorithm used to compute REML estimates may be slow or may even fail to converge. We develop a set of closed-form approximations to the REML estimator, and the performance of these estimators is compared with that of the REML estimator. We provide guidelines regarding how to choose the estimator that best approximates the REML estimator. Examples presented in the article suggest that the closed-form estimators compete with and, in some cases, outperform the REML estimator.

Magnets in prosthetic dentistry.

Magnetic retention is a popular method of attaching removable prostheses to either retained roots or osseointegrated implants. This review chronicles the development of magnets in dentistry and summarizes future research in their use. The literature was researched by using the Science Citation Index and Compendex Web from 1981 to 2000. Articles published before 1981 were hand researched from citations in other publications. Articles that discussed the use of magnets in relation to prosthetic dentistry were selected.

Regulation of cholesterol synthesis by oleic and palmitic acid in keratinocytes.

Cholesterol synthesis is essential for homeostasis of the epidermis, being required for both cell division and differentiation, as well as maintenance of the epidermal permeability barrier. Cholesterol synthesis in keratinocytes has been demonstrated to be regulated by sterol levels and the barrier function of the stratum corneum. Cholesterol synthesis in the epidermis is correlated with changes in mRNA levels for key enzymes, such as HMG-CoA synthase and HMG-CoA reductase, which have been previously demonstrated to be coordinately regulated by the sterol regulatory element binding proteins (SREBPs). In this study we demonstrate that a functional sterol regulatory element is required for sterol regulation of HMG-CoA synthase in keratinocytes. We also investigate the regulation of cholesterol synthesis by fatty acids, which are another important constituent of the stratum corneum lipids. Palmitic and oleic acid inhibit 14C-labelled acetate incorporation into sterols in a similar manner to sterols. However, unlike sterols, 50 microM oleic acid increase the steady state mRNA levels of HMG-CoA synthase and the activity of the HMG-CoA synthase promoter. The addition of 50 microM oleic acid to 25-hydroxycholesterol results in an enhancement of the inhibitory effect of the sterol on promoter activity. The inhibition of acetate incorporation into sterols in human keratinocytes by 50 microM palmitic and 50 microM oleic acid is not due to regulation of HMG-CoA synthase at the level of transcription.

A preliminary electron backscattered diffraction study of sintered NdFeB-type magnets.

This paper reports, for the first time, the use of electron backscattered diffraction (EBSD) to study orientation in sintered NdFeB type magnets. The magnetic properties of NdFeB magnets are greatly improved if a strong crystallographic texture is firstly achieved, namely, the direction of the c-axis is along the direction of magnetization. A systematic survey of sample preparation techniques showed that samples that were mechanically polished and then etched gave the most reliable EBSD data. Analyses were made using both fully automated EBSD scans and by EBSD measurements taken after manual movement of the beam. The EBSD results are presented as secondary electron SEM micrographs, orientation images and 001 pole figures. For the selection of grains investigated, the deviation of the c-axis was shown to be between 10 degrees and 30 degrees from the ideal [001]//magnetization direction. It is demonstrated that EBSD is a valuable tool for characterizing the microstructure and texture relationships and for assessing the performance of the processing routes of NdFeB magnets.

Calcium: a crucial consideration in serum-free keratinocyte culture.

This investigation was conducted when previously repeatable experimental data became impossible to reproduce when using keratinocytes cultured in serum-free medium. Differences in calcium molarity between batches of medium were identified as a source of variation in cultured keratinocyte populations. The susceptibility of cultured keratinocytes to even small alterations in calcium molarity has been demonstrated. 2 regular medium batches were compared with a special preparation of medium, devoid of calcium chloride then supplemented with a known concentration of calcium ions. Culture progress in each medium was assessed by: morphological observation, % cells expressing involucrin and proliferating cell nuclear antigen, cell attachment, growth rate and colony forming efficiency. In order to control the phenotype of cultured keratinocytes, in a reproducible system, it is recommended that serum-free keratinocytes medium is purchased with the omission of calcium chloride. Supplementation of this medium may then be made by the investigator to suit individual culture requirements.

Use of autografts for the treatment of leg ulcers in elderly patients.

Human keratinocytes obtained from seven elderly patients who had long-standing leg ulcers of venous or rheumatoid origin were grown into sheets for autografting on to their ulcers on at least one and, in some cases, two occasions. Following the application of the autografts on to the ulcers the appearance of the ulcer base improved with an increase in the vascularity of the granulation tissue and decrease in the amount of exudate. An 'edge effect' was also noted in five cases, with the previously indolent-looking edge of the ulcer appearing healthier and more active. However, over a 4-month follow-up period there was no complete re-epithelialization in any of the ulcers despite these initial improvements.