A methodologic study of the effect of dental materials on growth and adhesion of animal cells in vitro

abstract – An in vitro method was used to investigate the ability of animal cells to (a) grow in the proximity of various dental materials, (b) adhere to and grow on the surface of the same materials during long-term contact. Disks (30 × 1 mm), made from the different materials, were placed in the center of plastic Petri dishes and incubated with human epithelial cells (NCTC 2544) and mouse fibroblasts (L 929). The growth around and on the surface of the disks was followed by measuring the amount of deoxyribonucleic acid (DNA) and/or cell number. The cultures were stained with crystal violet to visualize the distribution of the cells. In the presence of gold alloy, growth was similar to that obtained in control cultures, whereas the other materials tested showed various degrees of a toxic effect. With the two heat-cured acrylics tested, a transient toxic effect was observed on the surface of the disks. In the presence of silicate cement, various degrees of growth inhibition were observed, both on the surface of and around the disks. A toxic effect of silver amalgam was evident on the surface of and in the close proximity of the disks, whereas Addent 12® and copper amalgam appeared to have a general toxic effect. The present method might thus be of value in the evaluation of the tissue compatibility of biomaterials.     

Silicate cement in a cell culture system

abstract — Human epithelial cells (NCTG 2544) were grown as monolayer cultures in the presence of silicate cement disks (Bio-trey 9®). A cytotoxic effect was found on the surface of the disks after 24 h, whereas a corresponding effect was obvious around the disks after incubation for 3 d. In the silicate cement cultures more glucose was utilized and more lactate formed per cell than in control cultures. In the presence of silicate cement, pH of the culture medium decreased during incubation, reaching 6.3–6.4 after 6 d. Phosphate, silicon, zinc, and fluoride were released into the medium from the silicate cement disks. The medium concentration of sodium, however, remained constant, and aluminum was not detected. The concentrations of calcium and magnesium decreased, and experiments with ⁴⁵Ca showed that calcium was bound to the silicate cement disks.     

Antibodies to Human Sinus Node in Sick Sinus Syndrome

The incidence of autoantibodies against human conducting tissue was studied in 45 pacemaker patients with sick sinus syndrome (SSS), in 17 patients with bradyarrhythmia, and jive patients with hypertensitive carotid sinus syndrome. Antibodies against the human sinus node were demonstrated in 29% of patients with SSS and in 24% of patients with bradyarrhythmia; a tenfold risk of SSS could be calculated in patients with this antibody as compared to age-matched controls. At least two subtypes of anti-sinus node antibodies were demonstrated: an antibody absorbable and another one not absorbable with ventricular myocardium. Patients with SSS and prior myocarditis of rheumatic fever have a threefold incidence of that antibody, demonstrating that anti-conducting tissue antibodies are etiologic indicators for former inflammatory heart disease. These antibodies may play a role in the secondary immunopathogenesis of sick sinus syndrome. This hypothesis emerges as an interesting new pathogenetic concept.     

Decreased monocyte inter leukin-1ß production in atopic eczema

It has been suggested that in atopic eczema (AE) a reduced lymphocyte response to T-cell mitogens in vitro is secondary to altered production of cytokines or inflammatory mediators. We investigated, in parallel, the mitogen-induced T-cell proliferation, monocyte interleukin-1ß (IL-1ß) production, and prostaglandin E2 (PGE2) production of monocytes and of peripheral blood mononuclear cells (PBMC) in AE patients and non-atopic controls. After stimulation with concanavalin A (Con A) PBMC of AE patients showed a significantly reduced proliferative response compared with the controls. The monocyte production of IL-1ß after stimulation with lipopolysaccharide (LPS) was significantly decreased in AE. No differences between AE patients and controls were observed with regard to the PGE2 production of PBMC after stimulation with Con A or the monocyte release of PGE2 after LPS stimulation. Because IL-1 plays a central role in the activation of T-cell proliferation, the decreased monocyte IL-1ß production may provide a plausible explanation for the reduced mitogen response of T cells in AE.     

Vibration, Acceleration, Gravitation, and Movement: Activity Controlled Rate Adaptive Pacing During Treadmill Exercise Testing and Daily Life Activities

Activity-based sensors for rate adaptive pacing have been available for several years and now include several different types: vibration; acceleration; gravitation; and movement. However, a systematic comparison evaluating the relative advantages and disadvantages of these various sensors has received little study. The purpose of the present study was to compare these sensor subtypes using treadmill testing and an outdoor test circuit, which simulated daily life activities and included both uphill and downhill walking. Pacemakers were strapped on the chest of healthy volunteers and connected to one channel of an ambulatory recording device, which also recorded the subject's intrinsic heart rate. The pacemakers were programmed using an initial treadmill test to standardize the rate responsive parameters for each device. Nine different pacemaker models were studied including 3 vibration-based (Elite. Synchrony, Metros). 4 acceleration-based (Relay, Excel, Ergos, Trilogy), 1 gravitational-based (Swing), and 1 movement-based (Sensorithm) device. All devices demonstrated a prompt rate response with casual walking on flat ground. The vibration-, gravitational-, and movement-based pacemakers showed a pronounced rate decline during more strenuous work, e.g., walking uphill. This phenomenon was absent in the accelerometer-based units. In particular, the vibration- and movement-based units showed a higher rate with walking downhill compared to uphill. An optimally tuned rote behavior on the treadmill usually did not provide an optimal rate behavior during daily activities and there was a tendency to overstimulation during low workload. The development of the two newest sensors (gravitational and movement) did not result in an improved performance of rate response behavior. Overall, the accelerometer-based pacemakers simulated or paralleled sinus rate behavior the most closely.     

Frequency and location of artificial crowns and fixed partial dentures constructed at a dental school

The material consists of patients who received single crowns and fixed partial dentures at the Department of Prosthetics, Dental Faculty, University of Oslo in the period 1967-73. Two-thirds of the patients were women, and about two-thirds of the restorations were made in the maxilla. A total of 3275 crowns were received by 2145 patients. On average, maxillary teeth were crowned 7 years earlier than mandibular teeth. A total of 1393 fixed partial dentures, consisting of 6835 units, were made for 1368 patients.     

Mercury concentrations in blood from Danish dentists

Abstract — Blood samples from a group of 130 dentists and a control group of 40 blood-donors were analyzed by cold vapor atomic absorption spectrophotometry in order to evaluate the extent of mercury exposure. The median blood concentration of mercury was 4.0 (range: 1.2–19.2) μg/1 for dentists and 2.0 (1.1–4.6) μg/1 for controls (2 P <0.01). Practice characteristics obtained in a questionnaire showed no statistically significant relationship to blood mercury, but 49 dentists having one or more fish meals per wk, had a median concentration of mercury, which was 47% higher than dentists seldomly consuming fish (2 P <0.01). It was concluded that none of the examined dentists had blood concentrations above the level (35 μg Hg/1) associated with the hygienic threshold limit.