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Biomedical subjects

G Schmalz

Publications and source records attributed to G Schmalz.

At least 91 records · Page 5Linked to original sources
PubMed1995

Mutagenicity of AH26 in an in vitro mammalian cell mutation assay.

The mutagenic activity of the root canal sealer AH26 was tested in the V79/hprt mammalian cell mutation assay. AH26 was mixed and eluted immediately after mixing or after setting times of 24 h or 7 days. Different amounts of dimethyl sulfoxide or physiological saline eluates were then tested for mutagenicity. Eluates of mixed AH26 were toxic and mutagenic, and both effects strongly depended on the setting time. The number of mutants after exposure to eluates of unset AH26 was enhanced approximately 7- to 10-fold. However, the mutagenic activity of the mixed material was clearly reduced after a setting time of 1 wk. Physiological saline eluates of the mixed AH26 were toxic at higher doses, but were not found to be mutagenic. Dimethyl sulfoxide eluates of the liquid component of AH26 elicited mutagenic effects similar to the freshly mixed material; eluates made in physiological saline were barely mutagenic at a 10-fold higher concentration. In accordance with recommendations of international guidelines, the V79/hprt mammalian cell mutation assay will be routinely used for the evaluation of the mutagenicity of dental materials in further investigations.

Animals↗
PubMed1995

Clinical and radiographical split-mouth-study on resorbable versus non-resorbable GTR-membranes.

The aim of this prospective split-mouth-study was to compare the 5-months-healing results after implantation of resorbable (Polyglactin-910) and non-resorbable (e-PTFE) GTR-membranes. 12 healthy patients with 41 periodontal defects were treated. Radiographical and clinical examinations (papillary bleeding index, gingival recession, probing pocket depth, probing attachment level, and furcation depth) were carried out under standardized conditions immediately before and 5 months after surgery. The vertical relative attachment gain (V-rAG) was calculated as a % of the bony defect depth (intra-operatively measured) at baseline, and the horizontal relative attachment gain (H-rAG) as a % of the furcation depth at baseline. The standardized radiographs were evaluated blind by 4 experienced examiners for changes of the alveolar bone. Furthermore, digital subtraction radiography was carried out using the standard deviation of the grey level histograms in the experimental region and in a control region as a test parameter for bone changes. Both types of membranes achieved an attachment gain. Using the split-mouth-design, no statistically significant (< or = 0.05) difference between the two membranes could be detected (number of defects/median) with regard to V-rAG (Polyglactin: 12/77.5%, e-PTFE: 12/73.2%) or to H-rAG of class-II-furcations (Polyglactin: 5/66.7%, e-PTFE: 5/66.7%), or to bone changes using conventional and subtraction radiographic evaluation. In conclusion based on this 5-months-study, the resorbable membranes provided attachment gain comparable to the e-PTFE-membranes.

Adult↗
PubMed1995

The biological evaluation of medical devices used in dentistry. The influence of the European Union on the preclinical screening of dental materials.

The advent of the European Union requires the biological evaluation of all medical devices used in dentistry prior to their general availability for clinical use. Biological evaluation is one component of the 'Essential Requirements' with which all devices need to conform. Such conformity will result in the issue of the CE mark. To facilitate this process, harmonised European standards are required. It is the policy of The European Committee for Standardisation (CEN) that, whenever possible, the relevant International standards will be adopted as European standards.

Animals↗
PubMed1994

Mutagenicity of dentin bonding agents.

Aside from the considerable number of reports on the physical and chemical properties of dental bonding agents, information concerning their biologic effects is sparse. Three dentin bonding agents (Prisma Universal Bond, Pertac Universal Bond, and Syntac) and the ingredients methylmethacrylate, 2-hydroxyethyl-methacrylate, and glutaraldehyde were investigated in the Salmonella typhimurium mutagenicity test system using five different bacterial strains (TA97a, TA98, TA100, TA102, and TA104). The materials as well as the ingredients were eluted in both dimethyl sulfoxide and physiologic saline, and serially diluted eluates were used in the plate incorporation test. Pertac Universal Bond and Prisma Universal Bond did not elicit any mutagenic effects in any of the bacterial strains. In contrast, Syntac adhesive showed clear mutagenicity in S. typhimurium strain TA102. Dimethyl sulfoxide eluates, as well as physiologic saline eluates of the Syntac bonding agent, caused numbers of revertants that were about 6 times higher than control values. Reversion rates with other strains were moderately enhanced. Glutaraldehyde, an ingredient of Syntac adhesives, caused mutagenicity in a manner similar to Syntac adhesive eluates. Neither 2-hydroxyethyl-methacrylate nor methylmethacrylate monomer was found to be mutagenic over a broad concentration range.

Carcinogenicity Tests↗
PubMed1994

Biological and clinical investigations of a glass ionomer base material.

OBJECTIVES: The purpose of this study was to investigate the biological properties of a new glass ionomer base material containing strontium glass. METHODS: The glass ionomer base material (Base Line, De Trey Dentsply) was tested for cytotoxicity using a standard agar diffusion test, for its effect upon the pulp in subhuman primates, and in a clinical study as base beneath both composite fillings and amalgam fillings. RESULTS: The material showed a cytotoxicity pattern similar to reference materials, a zinc phosphate cement and a reference glass ionomer base material, which are used successfully in clinical applications. With the pulp/dentin usage test in subhuman primates, there were no statistically significant differences between the experimental glass ionomer base material and the negative control group if bacterial contamination of the cavity floor or direct contact with the pulp was avoided. The results of the clinical study also indicated no pulp damage after one year. SIGNIFICANCE: The experimental glass ionomer base material proved to be acceptable both biologically and clinically.

Analysis of Variance↗
PubMed1994

Growth kinetics of fibroblasts on bovine dentin.

In vitro dentin barrier tests published so far show several shortcomings. Therefore, we designed a new test method using bovine dentin disks on which cells were grown on one side. In this study, we evaluated the growth kinetics of L-929 mouse fibroblasts on dentin disks of 0.75-mm thickness and 4-mm diameter derived from lower incisors of freshly slaughtered bovines. The application of 50% citric acid for 30 s was optimal for the gentle removal of the smear layer from the cut dentin slices. Growth kinetics of mouse fibroblasts depended on the initially plated cell density: optimal cell growth on the disks was observed with approximately 200 cells/mm2, which was the same as the growth rate on the bottom of a cell culture vessel. Consequently, bovine dentin disks are a suitable substrate for normal cell growth, and this set-up can be used in a dentin barrier test.

Acid Etching, Dental↗
PubMed1994

Characterization of an in vitro dentin barrier test using a standard toxicant.

To characterize a new artificial pulp chamber using bovine dentin, the influence of different phenol concentrations on the cell reaction was evaluated. Bovine dentin slices of 100, 200, 300, 500, and 700 microns were cleaned, sterilized, and mounted between two 5-mm-thick glass plates with a borehole of 5 mm in diameter. L-929 mouse fibroblasts were seeded into the "pulpal" part of the device and incubated for 24 h. Different concentrations of a phenol solution as a standard toxicant were applied to a sterile cotton pellet in the "cavity" side of the device. After incubation for 24 h, the cytotoxic reaction was evaluated by cell counting after vital staining with fluorescein diacetate and related to the negative control. A dependency of the cytotoxic reaction on the concentration of the standard toxicant and on the thickness of the dentin slice was demonstrated. The simple dentin barrier test using bovine dentin may be a suitable alternative to other more complicated procedures using human dentin.

Animals↗
PubMed1990

[Determination of caries risk in federal soldiers].

Using Dentocult/Dentobuff the "caries risk" was determined in 102 adult test persons three times within a period of 44 weeks and correlated with clinical and radiological study results (Spearman rank correlation, multiple calculation of correlation and regression). The patients were given dental treatment as required during the study period. A close correlation was seen between the individual Dentocult measurements taken at different times, which speaks for relative constancy in these measured values in individual test persons. No significant correlation with the overall increase in caries was found and did not become apparent until cases of caries were categorised as primary, secondary and smooth-surface types. The correlation coefficient was, however, low at R = 0.2-0.4. The prognostic value of the Dentocult/Dentobuff system was at best about 50%. A connection between the caries risk test and clinical parameters became evident in the presence of localised retention. On the whole, however, it must be said that our studies do not show that this method makes it possible to prognosticate the caries risk in individual patients.

Adult↗
PubMed1990

[Marginal fit of ceramic and composite inlays in vitro].

Direct and indirect composite and ceramic inlays exhibit a space between inlay and tooth, which is filled with a luting composite resin. The aim of the present study was to evaluate the influence of the width of this space upon the quality of the marginal seal of the inlay system. The marginal quality of class II-inlays with small (0.2 mm) and large (0.4 mm) spaces was examined using quantitative SEM analysis and dye penetration. Regular class-II composite fillings served as controls. After thermal and mechanical loading the composite inlays with the wider composite layer showed more marginal gaps than both groups of ceramic inlays. The ceramic inlays did not show a significant deterioration of the margins. The least amount of dye penetration was observed in ceramic inlays with a wider composite layer at the interproximal cavity wall. Composite fillings showed more dye penetration than inlays.

Ceramics↗
PubMed1990

[Root canal therapy--clinical results].

Clinical and radiographic evaluations of root canal therapy indicated, that after correct patient selection endodontic therapy is technically feasible in most cases (even in posterior teeth). Only in few cases (3%) did symptoms of flare ups (5.4-13.4%) last for more than one week. This rate could be further reduced by additional measures, such as the local application of antibiotics and steroids. Long-term success rates for root canal therapy have been reported to range between 71 and 96%. The patient's age and the type of tooth affected had no effect on prognosis. Teeth with periapical resorptions displayed slightly lower success rates. Failures were primarily attributable to overfilling or inadequate instrumentation and/or filling. Root canal therapy should be part of an overall treatment plan including considerations of primary and secondary prevention as well as each patient's individual needs.

Humans↗
PubMed1990

[Clinical comparison of different cervical fillings after one year].

Cervical lesions in 38 patients were restored using composite resins (n = 57), the "sandwich-technique" (n = 64) or glassionomercement (n = 66). Immediately following insertion and 4, 8, and 12 months later, the restorations were examined clinically and in the SEM. Two composite fillings and one filling each of the two other types of restoration were lost. After one year the quality of the dentinal margins of the composite restorations was statistically (p less than 0.05) inferior to the two other methods. Margin quality in enamel was rated superior (p less than 0.05) with glassionomercement as against the other materials. Clinically, the composite filling yielded poorer results regarding marginal integrity and discoloration, although in general they showed superior esthetics. In restoring cervical lesions the use of glassionomercements or the "sandwich-technique" has definite advantages over composite fillings. For the evaluation of new restorative materials and techniques, SEM should be used in addition to clinical examinations.

Adolescent↗
PubMed1990

[In vitro growth of periodontal ligament fibroblasts between bone and root slices].

In a first experiment the proliferation and growth kinetics of periodontal ligament fibroblast monolayers generated from human healthy (HPDL) and diseased (DPDL) periodontia were compared. In a second experimental series a periodontal ligament-like space was developed by laying a root slice inside a bony ring slice on the bottom of a tissue culture petri dish and leaving a space of about 0.5 mm between both structures. HPDL cells showed a higher proliferation rate than DPDL cells. Growing into the space between the slices, the PDL cells built up a matrix which was composed of cells and fibrils. HPDL cells built up the matrix more rapidly than DPDL cells.

Adolescent↗
PubMed1989

The role of proteoglycans in collagen gel contraction by human gingival fibroblasts.

Fibroblasts generated from biopsies of normal gingiva contract collagen gels to a significantly greater extent than do fibroblasts generated from chronically inflamed gingiva. The present study demonstrates that proteoglycans play a major role in gel contraction, and that cells from the two sources differ greatly in their ultrastructural features and their capacity to synthesize proteoglycans. Fibroblasts from normal gingiva contained more rough endoplasmic reticulum and mitochondria, and they were more well-spread than cells from chronically inflamed gingiva. We observed a fine granular electron-dense lamina of material especially prominent around the cell processes and on the surface of the collagen fibrils. This material appears to be rich in proteoglycans since it stained with ruthenium red, a dye that binds to proteoglycans, and labeled in cultures incubated for 1 or 4 hr in medium containing 35S-sodium sulfate. Proteoglycans have the capacity to bind matrix components to one another and to cells, and thereby play a major role in gel contraction. Normal fibroblasts have a significantly greater capacity to synthesize proteoglycans, as manifested by label incorporation, that do cells from inflamed tissue, and this may account for their greater capacity to contract collagen gels in vitro.

Collagen↗