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Results for “DENTAL AMALGAM”

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PubMed1989

Variation in human salivary pellicle formation on biomaterials during the day.

Contact angle measurements were used to study the effects of pellicle formation on polymethyl-methacrylate, dental amalgam and gold. Samples were exposed to saliva in vivo for periods of 5-20 min at three separate occasions during the day. Pellicle drastically increased the wettability of all the materials and effectively sealed off the effect of the original surface activity. Variation in pellicle formation during the day was demonstrated. Pellicles formed at midday showed the least reduction in contact angles compared to those formed during the morning and afternoon. This difference coincided with an increased concentration of inorganic phosphate in saliva at midday. The method enables comparative studies of pellicle formation on hard biosurfaces. The findings indicate differences in the physical behaviour of saliva during the day, and illustrate the importance of making adhesion studies with this variation in mind.

Adhesiveness↗

PubMed1989

A comparative study of the bond strengths of amalgam and alloy-glass ionomer cores.

The purpose of this study was to compare the bond strengths of dental amalgam cores and dental alloy-glass ionomer cores that were luted to cast gold crowns with glass ionomer cement. Seventy-two human extracted molars were sectioned horizontally and four regular thread mate system pins were inserted into a flat pulpal floor. The teeth were restored with amalgam or alloy-glass ionomer admixture and prepared for crown preparations. Castings were produced with type III gold and cemented to the cores with Fuji type I glass ionomer cement. Thirty-six of the specimens were subjected to thermal fatigue by cycling between 4 and 50 degrees C for periods of 1, 5 and 10 weeks. The remainder of the specimens were retained in deionized water at 37 degrees C. Bond strengths of the cores, in tension, were measured with a universal testing machine. The alloy-glass ionomer cores exhibited higher bond strengths than the amalgam cores for virtually all time periods, particularly the thermocycled samples. The alloy-glass ionomer cores exclusively displayed core fractures and pin/tooth insufficiencies while the amalgam cores failed because of a deterioration of the glass ionomer luting cement.

Crowns↗

PubMedDate not supplied

In vitro microleakage of four tracers with multiple applications to the same tooth.

Microleakage testing continues to be undertaken using a variety of techniques and methodologies. This study compared four microleakage tracers to determine if a difference exists in their ability to demonstrate microleakage on a single dental amalgam restorative material by testing in two phases. Class V amalgam restorations were placed on the facial surfaces of 105 extracted human premolars with all margins in enamel. The teeth were stored at 37 degrees C in water for two weeks except during thermocycling for 2500 cycles between 8 degrees C and 48 degrees C. The teeth were prepared for microleakage testing by sealing the external surfaces with nail polish and tinfoil, leaving the restoration and surrounding 1 mm exposed. In the first phase, four groups of 15 teeth were randomly assigned to 0.5% basic fuchsin dye, 2.0% fluorescent dye, 1.5% reactive orange 14 and 45Ca. In the second phase, another three groups of 15 teeth were immersed in 45Ca, then immersed in one of the remaining three tracers. Ridit analysis and Newman-Keuls multiple comparisons were used to compare the groups at a significance level of 0.05. The results indicate that there are differences in observed microleakage between tracers and there is no statistical influence on dye tracers by initial immersion in 45Ca.

Bicuspid↗

PubMed2006

Perceptions of how the Internet has impacted on dentistry.

OBJECTIVES: This study sought to identify how patient information on the Internet has influenced the delivery of oral care and the use practitioners themselves make of the Internet. METHODOLOGY: Data were collected via a self completed 18 item postal questionnaire, sent to a random sample of 620 dentists on the GDC register in Wales. RESULTS: In total 457 (74%) of the questionnaires were returned. One half of all practitioners stated that patients had asked them about material of relevance to dentistry obtained from the Internet, although in the majority of cases this happened less frequently than once a month. The most common topics enquired after were cosmetic procedures, dental amalgam and implants. A minority of dentists, 47 (11%) viewed the Internet as a threat to the dentist-patient relationship. However, 169 (39%) agreed information gained from the Internet had led to patients demanding inappropriate care or more complex treatment (135/31%). Having to take time to discuss Internet material was viewed as a burden by 93 practitioners. The potential of the Internet to widen inequalities in access to oral health information was agreed upon by one third of respondents. Concerns over the quality and reliability of Internet derived information, together with a lack of knowledge of appropriate sites, prevented dentists using the Internet as an oral health education resource. However, only 18.7% claimed never to use the Internet for their own Continuing Professional Development. Access for CPD purposes was mainly from home. Of those working in general practice, 54 had their own practice website, and a further 103 said this was something they were considering. Email was used to communicate with patients by 42 dentists, mainly to make appointments. CONCLUSIONS: Views on the impact of the Internet were generally positive, but there is a long way to go before its full potential is realised.

Appointments and Schedules↗

PubMed1999

Mercury and silver in saliva from subjects with symptoms self-related to amalgam fillings.

The amount of mercury released into saliva from dental amalgam fillings is currently being debated. Mercury enters saliva as vapor, ions and particles of amalgam. The aim of the present study was to determine mercury and silver concentrations in saliva of persons with amalgam fillings. Moreover, it was the aim to investigate whether amalgam particles were present in samples of stimulated saliva in control subjects. In that case, we also wanted to determine the influence of these particles on the mercury concentrations found. Fifty-three patients with a wide range of complaints self-related to their amalgam fillings were examined by the Dental Biomaterials Adverse Reaction Unit of Norway. Among other tests, stimulated saliva was collected from each patient and analyzed for mercury and silver. Mercury and silver correlated with the amount of amalgam present. There was a strong correlation between mercury and silver concentrations. Amalgam particles were found by energy dispersive X-ray analysis. It appears that a considerable part of the mercury and silver were present as amalgam particles. The present study shows that amalgam particles in saliva have to be controlled for when analyzing mercury in saliva from subjects with amalgam fillings.

Adult↗

PubMed2003

Evaluation of corrosion degradation of amalgams by immersion and fracture test.

In this study an immersion and fracture test was used to evaluate the susceptibility of dental amalgams to degradation of their mechanical strength by corrosion. Specimens of each of the six types of high-copper amalgams and one type of low-copper amalgam were prepared and tested. Cylindrical specimens were grooved using a diamond cutoff blade and immersed in 1% NaCl to which H2O2 was added to increase the oxidation power. After two weeks of exposure the specimens and controls were fractured and the loss of strength was calculated. Two amalgams showed a significant loss of strength. The test procedure is relatively simple and does not require sophisticated electrochemical or analytical instrumentation. A higher resolution power might be achieved by increasing the severity of corrosion or the number of replicate tests.

Corrosion↗

PubMedDate not supplied