Natural history of a proinsulin-secreting insulinoma: from symptomatic hypoglycemia to clinical diabetes.
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Blood Glucose↗
Biomedical subjects
N J Grey
Publications and source records attributed to N J Grey.
Repair of fractured porcelain units: alternative approaches.
Laboratory studies have demonstrated high bond strengths between a number of resin systems to metal and porcelain, as well as to tooth substance. In circumstances where fracture of a porcelain bridge or crown has occurred, it may appear reasonable to attempt a repair using one of these systems in conjunction with abrasion of the fractured surface, although current knowledge does not allow an accurate prediction of the longevity of the repair under oral conditions.
Acrylic Resins↗
Audit in restorative dentistry.
Auditing activity requires patient data to be collected and analysed to allow comparisons to be made and conclusions drawn. Within the General Dental Services the Dental Practice Board regularly collects practitioner specific clinical data and distributes this to allow dentists to compare their own clinical activity with local and national means. In hospital dentistry, a software package has been developed to enable orthodontic audit to be performed in hospital practice. The package is now being piloted in several centres. A similar software package is required for auditing restorative dentistry activity in units where consultant services are provided. Hospital patient administration systems provide demographic data and appointment systems predominantly with little opportunity for patient specific clinical analysis. Carefully designed software will allow appropriate clinical data and analysis. To ensure compliance and accurate recording both by clinical and support staff it is essential that any software system should be easy to use.
Dental Service, Hospital↗
In vitro comparison of conventional crowns and a new all-ceramic system.
Thirty-three crowns of similar size and shape were constructed to fit a standard brass die. Eleven crowns were manufactured from each of the following groups of materials: metal-ceramic, aluminous porcelain and a new all-ceramic system based on a glass infiltrated alumina coping. The overall fitting accuracy of each crown was determined using a low viscosity silicone paste, prior to cementation onto brass dies with zinc phosphate cement. The average film thickness was 95, 154 and 123 microns respectively. Each cemented crown was loaded to fracture. The mean load to failure of the glass infiltrated alumina crowns was significantly greater than that of the aluminous porcelain jacket crowns (P < 0.0001), but not significantly different from the metal-ceramic crowns.
Aluminum Oxide↗
An in vitro comparative analysis: scanning electron microscopy of dentin/restoration interfaces.
One hundred maxillary premolar teeth were randomly allocated to ten groups. Each group was restored with one of ten different restorative techniques. The teeth were stored in deionized water for 7d prior to longitudinal sectioning in a mesio-distal plane. Following sectioning, ten specimens from each group were chosen at random from the 20 available sections. The sectioned surfaces were polished using 600-grit SiC abrasive paper and etched for 10 s with 50% phosphoric acid to remove the smear layer produced by sectioning. Five tooth sections from the dentin bonding resin groups were allowed to dry at 20 degrees C for 24h. The glass ionomer-based groups were reimmersed in deionized water during this period. The remaining five sections from each group were replicated using an addition-cure vinyl polysiloxane impression material and an epoxy resin. A comparison was made of the sections and the replicas. All tooth specimens were sputter-coated with gold for 4 min and examined using a scanning electron microscope. Replicas were gold-coated for 3 min. Different tooth/restoration interfaces, associated with different materials, were observed. A marked difference between the replicas and tooth sections was observed for glass ionomer-based restorations but not for resin-based bonding systems. Representative samples of replicas and specimens are shown, and the significance of the observed differences is discussed.
Bisphenol A-Glycidyl Methacrylate↗
In vitro microleakage associated with posterior composite restorations used with different base/bonding system combinations.
The study aimed to determine the base/restoration combination which allowed the least microleakage in Class II cavities. One hundred premolar teeth were prepared with a standardized, minimal two-surface cavity and randomly ascribed to ten equal groups. The cavities were restored by use of one of ten different material/technique combinations. Restored teeth were sealed to within 1 mm of the restoration margins with nail varnish prior to the immersion of the crowns in 5% (buffered) eosin for 48 h. The teeth were then hemisected longitudinally, in a mesio-distal plane, through the midline of the restoration by means of a diamond disc with water coolant, and one half of each tooth was then photographed. The transparencies were examined by image analysis programmed to facilitate calculation of the percentage of the tooth/restoration interface and of the crown dentin exhibiting dye penetration. Light- and chemically-cured glass-ionomer-based restorations showed similar amounts of leakage when expressed as a percentage area of crown dentin. This was significantly (p less than 0.05) less than that shown by cavities both etched and bonded. Cavities restored without enamel etching or involving the use of a bonding system exhibited significantly (p less than 0.05) greatest leakage.
Acid Etching, Dental↗
In vitro marginal microleakage: examination of measurements used in assessment.
Premolar teeth with Class II amalgam restorations placed after the application of cavity varnish (Group A), a light cured glass ionomer base (Group B) and 40 per cent polyacrylic acid as a pretreatment agent, followed by unset cermet cement (Group C) were examined for marginal leakage using dye penetration and image analysis. Including amongst the parameters examined were linear leakage length and leakage area, which were found to have no consistent correlation. Group A and C did not generally show significant differences in the parameters examined, whereas Group B exhibited significantly less linear leakage (P less than 0.001), and significantly less leakage area when the stained area was expressed as a percentage of available dentine (P less than 0.001). While allowing some linear leakage, it was found that the light cured glass ionomer base appeared to prevent the dye from entering the dentine. It is concluded that an assessment based solely on the leakage length is inadequate and that some measurement of penetration into dentine should be included in order to fully assess the microleakage potential of a material or technique.
Acid Etching, Dental↗
In vitro marginal microleakage associated with five dentine bonding systems and associated composite restorations.
Fifty sound premolar teeth, extracted for orthodontic purposes and stored at room temperature in physiological saline since extraction, were prepared with a standardized minimal two-surface Class II cavity. The teeth were then ascribed randomly to five groups, each of ten teeth. Each of four groups was restored using a different dentine bonding system and the associated posterior composite resin according to the manufacturer's instructions. The fifth group was restored with Superbond C & B dentine bonding system and Occlusin composite. After immersion in de-ionized water for at least 7 days, the teeth were sealed with nail varnish to within 1 mm of the margin of the restoration. The teeth were then immersed in 5 per cent buffered Eosin for 48 h. Following mesiodistal sectioning the sections were photographed and subjected to image analysis to establish the length of dye penetration at the tooth/restoration interface and the amount of dye penetration into the crown dentine. Tripton/Occlusin and XR Bond/Herculite XR groups showed a significantly (P less than 0.05) smaller amount of leakage than Gluma/Lumifor or Scotchbond 2/P50 combinations when assessed as a percentage of the tooth/restoration interface exhibiting leakage. When the percentage of crown dentine showing dye penetration was considered, the Tripton/Occlusin group showed less leakage than the other material combinations. It is concluded that Tripton, when used with the recommended composite, will allow significantly less microleakage than Gluma/Lumifor, Scotchbond 2/P50 or Superbond C & B/Occlusin combinations and a similar amount to XR Bond/Herculite XR in vitro.
Acid Etching, Dental↗
Aesthetics and porcelain veneers.
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Adolescent↗
Physiologic mechanisms in the development of starvation ketosis in man.
The present study was undertaken to determine whether alterations in ketone body utilization and hepatic production, independent of the FFA load, were also involved in the development of fasting ketosis. Plasma Beta-OH butyric acid (Beta-OHB) increased to 2.5-4.5 mM and plasma FFA to 1,000-1,400 muEq/L. in normal weight individuals after five to seven days' starvation and in obese subjects after ten to fourteen days' fasting. Acute elevations fo the plasma FFA greater than 1,500 muEq/L. for sixty minutes in fed normal weight and obese subjects with a fat meal-heparin regimen resulted in peak elevations of plasma Beta-OHB (0.25-0.45mM), only 10 percent of that seen during fasting. When plasma FFA were lowered acutely during fasting with the antilipolytic agent Pyrazole to control levels (400-600 muEq/L.), plasma Beta-OHB decreased 35 plus or minus 5 per cent. Comparable lowering of plasma FFA in normal weight or obese starved subjects given dexamethasone to maintain elevated fasting plasma insulin levels resulted in an 87 plus or minus 3 per cent decrease in plasma Beta-OHB. Similar studies in obese fasted subjects pretreated with an intravenous infusion of insulin (1.0 U/hr. for eight hours) before receiving Pyrazole resulted in a 65 plus or minus 5 per cent decrease in plasma Beta-OHB. Plasma Beta-OHB half-life, determined after injections of 12 gm. Beta-OHB, increased significantly during fasting (110 plus or minus 15 minutes) and was decreased when the fasting subjects were maintained on dexamethasone (65 plus or minus 7 minutes). These studies indicate that accelerated hepatic ketogenesis during starvation is a result of both enhanced activity of the enzymatic system(s) involved in ketone body production as well as an increased FFA load. The increase in plasma Beta-OHB during fasting reflects not only an accelerated rate of hepatic ketogenesis but also an impairment of peripheral utilization, both processes apparently being sensitive to insulin. Diabetes 24:10-16, January, 1975.
Acidosis↗
The effect of fasting, diet, and actinomycin D on insulin secretion in the rat.
The present studies were performed to elucidate the mechanisms responsible for the impairment of glucose-stimulated insulin secretion observed in fasting. Rats fasted for 48 hr displayed marked impairment in their insulin secretory response to both oral and intravenous glucose. Glucose-stimulated insulin secretion was restored within 24 hr by refeeding; actinomycin D given before refeeding blocked the expected return of normal glucose-stimulated insulin secretion despite adequate food intake. Fasted rats refed a diet devoid of carbohydrate failed to display a return of normal insulin secretory responsiveness to oral glucose in contrast to rats fed isocalorically a high carbohydrate diet. Differences in insulin secretion in fed, fasted, and fasted-refed rats could not be attributed to changes in pancreatic insulin content. There was no significant difference in the insulin secretory response to aminophylline of fed, fasted, or fasted-refed rats. The intermittent pulsing of fasted rats with hyperglycemic episodes by the injection of small amounts of glucose (500 mg) intraperitoneally every 8 hr ameliorated the impairment of glucose-stimulated insulin secretion characteristic of the fasting state. These results suggest that the impairment of glucose-stimulated insulin secretion during fasting and its restoration by refeeding are regulated by changes in a glucose-inducible enzyme system in the pancreatic beta cell.
Administration, Oral↗