Margareta Molin

Mercury, selenium, and glutathione peroxidase before and after amalgam removal in man.

In 10 healthy persons all amalgam fillings were replaced with gold inlays. Blood and urinary levels were measured on 10 occasions during a 4-month period before and a 12-month period after amalgam removal. These variables were also measured three times in 10 healthy controls. A strong statistically significant relation was found between plasma mercury values and both the total number of amalgam surfaces (r = 0.71, p = 0.0006) and the total surface area of the fillings (r = 0.73, p = 0.0004). In the immediate postremoval phase plasma mercury rose three- to four-fold, whereas the urinary and erythrocyte mercury rose about 50%. These peak values declined to the preremoval level at about 1 month. Twelve months after the removal the plasma and urinary mercury levels were significantly reduced to 50% and 25%, respectively, of the initial values for the experimental group. Apart from the significantly lower plasma selenium values 5 and 10 days after removal no significant differences were found with regard to plasma selenium or erythrocyte glutathione peroxidase either within or between the experimental and the control groups. A large number of supplementary biochemical analyses did not show any influence on organ functions or any differences between the groups before or after the amalgam removal. Amalgam fillings considerably contributed to the plasma and urinary mercury levels.

The fit of gold inlays and three ceramic inlay systems: A clinical and in vitro study

Four inlay systems--gold, Cerec, Mirage, and Empress inlays--were evaluated for their adaptation to stone die and clinically to the tooth by means of a replica technique. Twenty inlays of each system were placed on premolars and molars in the lower jaw. A microscope was used to measure the adaptation at the approximal margin, at the inner axial wall, and at the occlusal cavosurface area. An overall better fit was observed for the gold inlays than for the ceramic inlays. When the different measuring locations were compared, a better fit was found for the occlusal area. The greatest discrepancies were recorded for the Cerec inlays, whereas the Mirage and Empress inlays were comparable.

Influence of film thickness on joint bend strength of a ceramic/resin composite joint

OBJECTIVES The purpose of this study was to evaluate the influence of different film thicknesses of resin composite luting agents on the joint bend strength of a ceramic/resin interface. METHODS Mirage FLC (Chamelon Dental Products) and Vita Cerec (Coltène AG) duo cement were used in combination with the ceramic materials, Mirage and Vita Cerec blocks. Cement layers with thicknesses of 20 microns, 50 microns, 100 microns and 200 microns were light-cured with a high-intensity curing light. Ten specimens of each ceramic/cement combination and thickness provided a total of 80 complete test specimens. Each specimen was placed in a four-point bending jig mounted in a universal tensile testing machine and underwent loading. A paired two-tailed Students 1-test was used to evaluate differences between different series of film thicknesses and resin cement combinations. RESULTS Within each ceramic/cement combination, the bond strength values were significantly lower for the 20 micron film then the thicker films. SIGNIFICANCE Taking into account the physical and clinical properties of resin-based luting agents, available knowledge indicates that a marginal gap on the order of 50-100 microns seems to optimize performance.

A clinical examination of ceramic (Cerec®) inlays

Two hundred and five Cerec ceramic inlays placed by 8 dentists in 72 patients were examined independently by 3 calibrated evaluators 12-24 months after insertion, using the criteria of the California Dental Association (CDA) and also certain periodontal variables. Proximal dental plaque and bleeding on probing were not seen more often on Cerec surfaces than on control homologous surfaces. Ten patients reported postoperative sensitivity after treatment with Cerec inlays. Excellent CDA ratings for Color and Surface were obtained in 57% and 26%, respectively, and for Anatomic Form and Margin Integrity in 55% and 83%, respectively. Obvious differences were seen among the participating dentists with regard to the clinical quality of Cerec inlays. At present, the long-term performance of the Cerec technique cannot be predicted.

Mobilized mercury in subjects with varying exposure to elemental mercury vapour.

SummaryIn a mercury mobilization test, 0.3 g of the complexing agent sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) was given orally to 10 workers with moderate occupational exposure to elemental mercury vapour, controls, and to 5 referents without amalgam fillings. In the workers, DMPS caused an increase in 24-h urinary mercury excretion by a factor of 10; in the dentists, 5.9; in the controls, 5.3; and in the amalgam-free referents, 3.8. Of the mercury excreted during 24 h, 59% appeared during the first 6 h. Close, albeit non-linear, associations were found between mobilized mercury and the premobilization mercury levels in plasma and urine, but not with the duration of occupational exposure or the rough estimate of the integrated function of blood levels vs. time. The present data indicate that mercury mobilized after a single DMPS dose in close connection with exposure is mainly an index of recent exposure and is not significantly affected by slow body pools or long-term exposure.

Ceramic inlays (Cerec) cemented with either a dual-cured or a chemically cured composite resin luting agent A 2-year clinical study

On the basis of the criteria of the California Dental Association (CDA), 66 CAD/CAM-manufactured ceramic class-II inlays (Cerec) were compared intraindividually after they had been cemented with either a chemically cured or a dual-cured composite resin luting agent in 27 patients. Plaque and gingival conditions, the overall time consumption for producing each inlay, and the frequency of postoperative sensitivity were also evaluated. There was no statistically significant difference between the two luting agents with regard to the properties evaluated. One inlay was replaced owing to fracture of the restored tooth just before the 24-month re-examination. After 2 years excellent CDA ratings were obtained for color in 92% of the remaining 65 inlays. The corresponding figures for surface and for anatomic form were 100% and 85%, respectively. For margin integrity 85% of the 33 inlays cemented with the dual-cured luting agent and 88% of the 33 inlays cemented with the chemically cured luting agent were rated excellent after 2 years.

An in vivo study of glass ceramic (Dicor®) inlays Preliminary report

For the purpose of evaluating the clinical quality of glass ceramic (Dicor) inlays 15 patients with 37 inlays were examined 1 to 22 months after placement. In addition to certain periodontal variables, the inlays were rated by two independent examiners using the California Dental Association (CDA) quality evaluation system. The results of the present study showed that dental plaque was seen less often on proximal surfaces with inlays than on homologous proximal surfaces. Three patients reported hypersensitivity of the dental pulp. The examination using the CDA criteria showed that 54% of the inlays had a slight color mismatch, and slightly roughened surfaces were occasionally seen (35.5%). In nearly 30% of the inlays there was visible evidence of ditching along the margins. At present, no judgement can be made about the longevity of ceramic inlays.

A clinical evaluation of conical crown retained dentures

In an uncontrolled retrospective recall study of 57 patients treated with conical crown retained dentures, 60 restorations (37 in the maxillae and 23 in the mandible jaw) with a mean wearing time of 30.1 months (range 4 to 76) were evaluated. Of the 248 abutments, eight (3.2%) had been lost. Clinically healthy mucosa was seen in 35 jaws. The marginal fit of the copings was judged to be good. No caries or new restorations were observed in 44 patients. Thirteen patients had 19 surfaces with new restorations and 20 surfaces with caries lesions. Of these 39 surfaces, 38 were located subgingivally.

A clinical evaluation of the Optec inlay system.

To evaluate the clinical quality of ceramic (Optec) inlays, the inlay production of 10 dentists, served by 3 dental laboratories, was examined independently by 2 calibrated examiners. A total of 57 patients with 205 inlays (mean age, 8.1 months) were examined 1 to 32 months after placement by means of using a slightly modified form of the California Dental Association criteria. Periodontal variables such as plaque index, gingival index, and margin index were also recorded. Eight patients reported postoperative but not persistent hypersensitivity in relation to the Optec therapy. No differences between Optec proximal surfaces and homologous control surfaces were seen with regard to plaque or bleeding on probing. The examination using the CDA criteria showed that 59% of the inlays had a slight color mismatch. Slightly roughened surfaces were most common (86%). As to anatomic form and margin integrity, 24% and 67%, respectively, of the inlays were rated excellent. A difference between the dentist with regard to the clinical quality of the inlay treatment procedure was seen. The present results cannot allow a definitive judgement with regard to the long-term clinical quality of the Optec inlay system but will serve as a base for further studies.

The influence of dental amalgam placement on mercury, selenium, and glutathione peroxidase in man

Amalgam restorations were inserted in eight healthy persons, previously unprovided with dental restorations, who had several severe carious lesions. The mean number of surfaces restored were 16.1 (range, 11 to 22). The total mean calculated amount of mercury inserted was 2.9 g (range, 1.5 to 4.3 g). Blood and urinary levels were measured on seven occasions during a 4-month period before and a 3-month period after amalgam placement. One and 3 months after placement, the P-mercury mean values were almost equal to the preplacement values (3.3 nmol/l). After placement U-mercury increased continuously; 3 months after placement a statistically significantly higher (p less than 0.05) mean U-mercury value (0.58 nmol/mmol creatinine) was found compared with the mean preplacement value (0.34 nmol/mmol creatinine). No statistically significant correlation was found between the P- and U-mercury concentrations and the total number of amalgam surfaces. Selenium levels in plasma and urine and erythrocyte glutathione peroxidase showed no systematic change of pattern. The results show that the insertion of amalgam fillings contributed to the U-mercury concentration, but apparently even more extensive amalgam therapy and/or longer exposure periods are needed to affect the P-mercury concentration. No negative effects on the P- and U-selenium or the erythrocyte glutathione peroxidase levels could be found during the 3 months immediately after an extensive amalgam placement. The supplementary blood and urine analyses were not influenced by the insertion of amalgam fillings.