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Biomedical subjects

K Nilner

Publications and source records attributed to K Nilner.

At least 55 records · Page 3Linked to original sources
PubMed1990

Oral electrochemical action after soft drink rinsing and consumption of sweets.

The aim of this study was to investigate the influence of pH changes in dental plaque and saliva on the magnitude of the galvanic current created when amalgam restorations make contact in the oral cavity. Ten persons with 46 contacts between amalgam fillings in all participated in the experiments. Potential, polarization, and pH measurements were performed before and after Coca-Cola and orange juice rinsing and intake of sweets, which were used as test products. Distilled water was used as a control. The measurements were performed 2, 5, 10, 20, and 30 min after the rinsing or intake. There was no statistically significant difference in the current magnitude after any test product or between the time intervals after the different products. The results indicated that changes of the plaque and saliva pH for a short time after food and soft drink intake do not influence the magnitude of the galvanic current flowing between amalgam restorations in contact.

Adult↗
PubMed1990

Guinea pig maximization test with a polyether impression material.

Adverse reactions to a polyether rubber impression material introduced in the mid-sixties have been reported in the literature. Most of the reports are inconclusive regarding the distinction between allergic and toxic responses. The aim of this study was to assess the allergenic potential of this material using a guinea pig maximization test. Ten guinea pigs in the experimental group were sensitized in two steps. First, an extract of the material was injected intradermally, and 7 days later, the material mixed in petrolatum was applied topically. After another 2 wk test solutions were applied, and the skin response was evaluated by visual inspection. Ten nonsensitized animals served as controls. From the challenge test it was evident that the catalyst as well as the freshly mixed material elicited positive skin reactions interpreted as being delayed hypersensitivity reactions. The findings indicate that the material contained substances which could be classified as strong to extreme sensitizers. Some of the adverse reactions seen in connection with the use of this material might well be related to delayed hypersensitivity reactions.

Allergens↗
PubMed1989

Relationship between oral symptoms, salivary function, smoking habits and general health in patients with complaints related to dental restorative materials.

Eighty consecutive patients, referred to the Department of Prosthetic Dentistry, Public Dental Service, Stockholm, for examination of complaints related to dental restorative materials or for supposed adverse effects from mercury released from dental amalgams were investigated. Clinical examination as well as battery of laboratory tests were performed. Statistical correlations were found between subjective and objective oral symptoms and lowered pH-values in stimulated saliva (p less than 0.001) as well as between objective oral symptoms only and lowered pH-values in stimulated saliva (p less than 0.001), which indicate salivary tests to be a useful tool when examining this type of patients.

Adult↗
PubMed1986

In vitro testing of dental materials by means of macrophage cultures. I: Methodological aspects.

Macrophages play a central role in the pathogenesis of inflammation. In addition, activated macrophages are the first cells to come in contact with foreign particles in tissue. In the present study the applicability of macrophages for in vitro biological screening of dental materials was tested. Monolayers of murine peritoneal macrophages were prepared. After three days culture the macrophages were inoculated with alloy particles prepared from silver and tin (Ag3Sn), the gamma-phase of dental silver-amalgam. After different inoculation periods the macrophages were fixed and examined with phase contrast microscopy, scanning electron microscopy, and energy dispersive x-ray analysis. Comparison with phagocytosis of particles injected intraperitoneally was also performed. Macrophage cultures inoculated with Latex particles served as controls. Ten minutes after inoculation with alloy particles, about 58% of the macrophages had ingested particles. EDAX-analysis indicated that the phagocytized alloy particles contained both silver and tin in the same proportions as in the original alloy. When the cultures had been inoculated for ten days, however, a marked reduction in phagocytosis was observed probably due to cytolysis of those macrophages which initially had phagocytized the alloy particles. The results indicate that, although the Ag3Sn alloy particles at all the time intervals studied were phagocytized more slowly and to a lesser extent than the Latex particles, the method could be of value in studying the biocompatibility of dental materials available in particulate form.

Animals↗
PubMed1986

In vitro testing of dental materials by means of macrophage cultures: II. Effects of particulate dental amalgams and their constituent phases on cultured macrophages.

It is known that macrophages play an important role in the removal of foreign particulate matter from tissue. When powdered dental amalgam is introduced into the soft tissues an amalgam tattoo is formed due to the intracellular degradation of amalgam by macrophages and their polykaryons. It was therefore feasible to study the effects of particulate amalgams as well as their individual phases on macrophages in vitro. The parameters compared were rate of the phagocytosis, changes of cellular morphology, and release of lactate dehydrogenase (LDH) to demonstrate plasma membrane permeability. It was shown that all the alloys except the Sn8Hg particles (gamma 2-phase) and gamma 2-containing Revalloy were effectively phagocytized by macrophages, and the alterations in cellular morphology were slight during the first day. Prominent cellular damage was seen in cultures treated with particulate Ag2Hg3 (gamma 1-phase) and Revalloy for 1 week. A slight increase in LDH activity in the medium was seen one hour after the alloy treatment. The LDH activities due to the amalgam treatment increased in the order Dispersalloy less than Revalloy less than Sybraloy. Intraperitoneal phagocytosis did not cause any morphological changes in macrophages, but the per cent of phagocytosis was diminished.

Animals↗
PubMed1985

Electrochemical potentials of amalgam restorations in vivo.

The potentials of 407 amalgam restorations have been determined in vivo. The measurements were performed with very high impedance equipment, and relative to a Ag/AgCl reference electrode. The readings varied from -23 mV to -595 mV, with 90% of the readings confined to within -127 mV to -431 mV and a mean value of -226.1 mV. Of the restorations, 394 were measured twice, and no significant difference could be found between the first and the second reading. During the study, eight new restorations were inserted. Their potentials varied from -180 mV to -565 mV, with a mean of -339.4 mV, which was significantly lower than that of the older restorations.

Adult↗
PubMed1985

Effect of dental amalgam restorations on the mercury content of nerve tissues.

In an autopsy study in two men and an experimental study performed on three female beagles the mercury burden of nerve tissues was determined. Nerve tissues from the head and face region and from three peripheral nerves were analyzed for mercury content with the aid of atomic absorption spectroscopy. In the dogs dental amalgam restorations were placed so as to investigate the possible influence from the amalgam on the mercury content of the tissues under study. The mercury content in man and dogs differed widely from one nerve to another, with no apparent relation to the number, type, or location of tooth restorations.

Aged↗
PubMed1985

On electric current creation in patients treated with osseointegrated dental bridges.

Electric currents are created when metals or metal alloys are immersed and make contact with each other in an electrolyte. As such metallic contacts are created in the oral cavity also at treatments with osseointegrated fixed bridges ad modum Brånemark, the generated currents were studied in vivo. In four subjects, all wearing osseointegrated mandibular dental bridges and complete maxillary acrylic dentures, the bridges were removed leaving the osseointegrated titanium abutments exposed in the oral cavity. Potentials and polarizations were determined independently for all the titanium abutments and gold alloy bridges and from the obtained data the maximum electric currents generated at contact between the materials were calculated. The results of this study showed that, generally speaking, in the oral cavity dental gold alloy was electrochemically more noble than titanium implants. The mean potential difference between the two metallic systems was found to be 73 mV and the mean generated maximum electric currents was in the magnitude of 26 microA at oral contacts between titanium and dental gold alloy.

Dental Abutments↗
PubMed1984

Quality of extensive fixed prosthodontics after five years.

A group of 150 patients who had received extensive restorative treatment 5 years prior to this study was selected at random from the Swedish Dental Insurance System records in Malmo. Of the 133 respondents to a questionnaire, 109 participated in a clinical evaluation of 891 restorations including 498 crowns, 232 pontics, 6 removable partial dentures, and 155 adjacent or opposing metallic restorations. The clinical evaluation was performed by two trained examiners by means of the CDA quality evaluation for dental care. Ninety percent of the crowns and pontics, 80% of the adjacent or opposing metallic restorations, and all six partial dentures were rated satisfactory. Twenty-three percent of the crowns, 49% of the pontics, 17% of the adjacent or opposing restorations, and half the partial dentures rated in the range of excellence. Not acceptable ratings for crowns included 3.4% T ratings and 6.6% V ratings. For pontics, the corresponding percents were 9.5% and 0.4%, respectively. T ratings were in most cases indicative of overcontouring, whereas V ratings for crowns were usually given because of secondary caries. Marginal periodontitis was mainly associated with not acceptable ratings but was also observed in connection with satisfactory restorations. Only 2% of the restorations had been lost during the 5-year period after insertion.

Adult↗
PubMed1983

Clinical evaluation of patients referred with symptoms related to oral galvanism.

Sixty-eight consecutive patients (9 males, 59 females) referred for symptoms alleged to be caused by oral galvanism were investigated according to a standardized examination program including clinical examination, epicutaneous patch test with dental materials, haematologic screening, salivary test, calculation of currents created at metallic contacts between restorative materials and testing of electrical taste thresholds. No clinical entity could be identified but recognized clinical conditions that could possibly explain the complaints for which the patients were referred were prevalent. The most common symptoms reported were a smarting sensation in the mouth (71%) and different distant symptoms (47%). As regards oral signs, some of them showed similar prevalences as have been found in a general Swedish population. The main exception was changes at the apex of the tongue - found in 15%. Allergic skin reactions to dental materials were found among 25% of the patients. Mean values of blood and saliva parameters did not differ from what is considered normal. The distribution of currents created by contacting dental metallic restorations showed no deviation from the corresponding currents calculated in a control group. The median value for lowest electrical taste threshold in the group of referred patients was significantly lower than in a control group.

Adolescent↗
PubMed1982

On intraoral potential- and polarization-measurements of metallic restorations. A methodological and time dependent clinical study.

A study was conducted to scrutinize the precision of a method for in vivo potential and polarization measurements. The variation with time of the magnitude of currents created at contacts between metallic dental restorations of varying age was also studied. The precision found indicates that the method allows for comparatively precise measurements of potentials to be taken. Studies of performed measurements of polarizations show that the precision of these measurements varies somewhat with contact conditions and the areas of restorations examined. The precision of the currents calculated was found sufficient for precise enough calculation to be made of the magnitude of currents created in the oral cavity. The study also shows a decrease with time of the magnitude of currents created at contact between metallic dental restorations of varying age.

Adult↗
PubMed1982

Oral galvanic action after treatment with extensive metallic restorations.

An epidemiological study was performed in 250 persons who five years previously had been treated with extensive metallic reconstructions. To gain representative information these persons were selected at random from three Local Social Insurance Offices in different parts of Sweden. Those person, who in a questionnaire reported symptoms that could be alleged to have been caused by oral galvanic actions, were offered free clinical examination including quality evaluation and free measurements of potentials and polarizations of the metallic dental restorations. Persons from a subgroup to this study not suffering from any oral discomforts were chosen as a control group. Comparisons between the two groups were made in regard to current creation at metallic contacts, clinical quality and mucosal conditions. In none of the statistical analyses performed, differences could be shown between the groups. A tendency to higher amounts of restorative care at comparatively lower level of technical quality could, however, be noticed in the group of persons with oral symptoms which they themselves associated with oral galvanism.

Aged↗
PubMed1982

Intraoral currents and taste thresholds.

A group of patients, with oral symptoms such as oral smart, battery taste and mental taste, were examined to study the relationship, if any, between intraoral currents, created at metallic contacts between restorative materials, and taste perception thresholds. The patients were examined with an electrogustometric method for determination of taste threshold levels. Further the intraoral currents were calculated from data obtained at potential and polarization measurements. Comparisons were then between groups of subjects with and without oral symptoms. The results of this study indicate that patients with certain oral symptoms have lower threshold levels for electric taste stimulation than persons in a control group selected at random. No differences were, however, observed between the magnitudes of intraoral currents in the two groups.

Adult↗