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Biomedical subjects

C Prati

Publications and source records attributed to C Prati.

At least 73 records · Page 4Linked to original sources
PubMed1990

Effects of chemical pretreatments on dentin bonding.

The aim of this study was to evaluate several chemical pretreatments on the shear bond strength of three dentin bonding agents (DBAs) and to try to correlate dentin morphology with bond strength using scanning electron microscopy (SEM). The DBAs tested were: Gluma Primer in association with Scotchbond DC, Scotchbond DC alone and Clearfil New Bond. Bond strengths of Scotchbond DC and Clearfil New Bond were not significantly modified or reduced by acidic dentin pretreatments. Gluma/Scotchbond adhesion was increased by several treatments but only maleic acid treatment produced shear bond strengths significantly higher than EDTA treatment. SEM evaluation of dentin treatments revealed a wide variety of morphological changes in the dentin surface with partial and complete removal of smear layer by acidic solutions, and only minor modification by amino acid solutions. Only maleic acid was capable of the complete removal of the smear layer and smear plugs coupled with extensive exposure of dentin collagen fibrils.

Acid Etching, Dental↗
PubMed1990

Shear bond strength and SEM evaluation of dentinal bonding systems.

Shear bond strength of seven dentin bonding systems (DBS) was evaluated. After shear bond testing, the specimens were analyzed under scanning electron microscope (SEM). Buccal dentin just below the dentin-enamel junction of erupted third molars of young subjects were used. A statistical difference was observed among the material bond values. SEM examination of both sides of the sheared bonds frequently showed an adhesive failure between dentin and bonding agents in the specimens where resin penetrated into the opened dentinal tubules. A complex cohesive fracture of both resin and dentin was observed for bonding agents that required the treatment of the smear layer, while a cohesive fracture in the smear layer thickness was noted when dentin was not altered by primer solutions. The study demonstrated that the DBS that require the removal of the smear layer showed a significantly higher shear bond strength and that the bond value reflects the mode of material fracture and the presence of smear layer.

Composite Resins↗
PubMed1990

[Glass ionomer cements and dentinal pretreatments: the evaluation of their adhesion to the dentin].

The aim of the present study was to evaluate the shear bond strength test of two glass-ionomer cements (G C cement and Ketac Bond) after different chemical pretreatments of dentine surface. The following dentine pretreatments were used: sodium hypochlorite, polyacrylic acid, tannic acid, H3PO4, FeCl3, Fe ossalate, Tubulicid, H2O2 and aqueous solution as control. Flat dentine surface of human extracted teeth was treated with the chemical agents, washed and dried. Cylindrical specimens of glass-ionomer cement were applied on dentine surface. After 24 hours in humidifier the specimens were tested in a universal testing machine. A significant higher bond was obtained only from polyacrylic acid and sodium hypochlorite treatments. The present results suggest that dentine pretreatment represent an essential step in composite resin/glass-ionomer cement restorations.

Adhesiveness↗
PubMed1989

[Dentin adhesives and the traction test. Comparative evaluation].

This study evaluated the shear bond strength of six dentinal bonding agents and one unfilled enamel bond in association with a microfilled composite resin. Eight specimens were prepared for each product. All the bonded samples were stored at 37 degrees C for 24 hours in a humidifier. Bond strength was measured with a universal testing machine. A statistically significant difference was found between the various products. The new dentinal bonding agents gave the highest bond value.

Composite Resins↗
PubMed1989

[Early marginal infiltration and Class II cavities].

The purpose of the present study was to evaluate the early marginal microleakage in 20 Class II MOD restorations made in association with conventional and sandwich technique. Human extracted third molars were used in the study. Multi-incremental technique was used in all restorations. After finishing, the teeth were stored in dye solution for 12 hours, transversally sectioned at three levels and evaluated under optical stereomicroscope. Cervical sections showed the highest marginal leakage. Sandwich technique in association with glass-ionomer cements have showed a significant lower early microleakage with respect to the conventional technique.

Composite Resins↗
PubMed1989

[Surface polishing of anterior composites].

In this research it has been valued at SEM the smoothness degree of the surface obtained in vitro on three kinds of composite resins for anterior restorations (Lumifor, Silux, Pekalux). The surface has been polished and finished with abrasive disks (Sof Lex Pop On XT). The composite resin Lumifor presents at SEM a good finished surface. Far better results have been obtained with the microfilled composite resins Silux and Pekalux, which show at SEM surfaces perfectly polished and homogeneous.

Composite Resins↗
PubMed1989

Effects of acid and cleansing agents on shear bond strength and marginal microleakage of glass-ionomer cements.

The aims of the present study were to evaluate the effects of various dentin chemical pretreatments (a) on the shear bond strength of five glass-ionomer cements (GICs) and (b) on marginal microleakage of the five GICs used in association with resin composites in Class V restorations. The dentin treatments were: three acid agents (polyacrylic acid, tannic acid, orthophosphoric acid), three cleansing agents (Tubulicid blue solution, hydrogen peroxide, and sodium hypochlorite), and an aqueous solution as control. After dentin treatment, the test specimens were stored in water at 37 degrees C for 24 hr. Shear bond strength was determined with a universal testing machine at a cross-head speed of 0.5 cm/min. Sodium hypochlorite and polyacrylic acid significantly improved the adhesion of GICs to a different degree in the various materials. Regarding microleakage tests, 320 non-retentive cavities were prepared at the cementum-enamel junction in freshly extracted human teeth. The teeth were thermocycled, immersed in dye solution, and serial-sectioned longitudinally at three sites. Treatment with sodium hypochlorite was the most effective in reducing marginal leakage. The present results suggest that dentin treatment is an important step in all resin composite/GIC restorations.

Acid Etching, Dental↗
PubMed1989

Early marginal microleakage in Class II resin composite restorations.

The aim of this study was to evaluate in vitro the early marginal microleakage around conventional and sandwich Class II (MOD) restorations. Ten different combinations of dentin bonding agents, glass-ionomer cements, and posterior resin composites were used. Class II cavities were prepared in freshly extracted third molars whose root surfaces had previously been coated. All gingival margins were prepared at the cementum-enamel junction. Teeth were filled by use of a multi-incremental technique, finished with discs, and immediately immersed in 2% erythrosin B for 12 h at 37 degrees C. Three transverse sections were made at 0.5 mm, 2 mm, and 3.5 mm over the cementum-enamel margin and evaluated under a stereomicroscope. Microleakage was scored linearly along the dentin/enamel-restoration interface. Sections at the cementum-enamel level showed significantly higher microleakage than the other two. Significant differences were observed between the various combinations of materials. Early marginal microleakage in Class II restorations depends not only on filling technique and on dentin bonding systems but also on the resin composite. Glass-ionomer cements significantly reduce early marginal microleakage in Class II restorations.

Composite Resins↗
PubMed1989

[Dentinal adhesives and glass ionomer cements: which are the best?].

The aim of this study was to examine the degree of marginal infiltration in vitro of some different dentinal bonding agents and glass ionomer cements in class V cavities prepared at cementum-enamel junction. A microfilled composite resin was used in all the cavities. Two-hundred and fifty thermocycle tests were performed after the samples had been in water for 24 hours. After evaluation under optical stereomicroscope, statistically significant differences between the various bonding systems were revealed. It would appear that the new generation of dentinal bonding systems, e.g. Scotchbond 2, Gluma Bond and Superbond, offer significant better in vitro results.

Dental Cavity Preparation↗
PubMed1989

Cytophilic antibodies cause leucocyte migration inhibition in coeliac disease.

Leucocyte migration inhibition in response to challenge with gluten fraction III was prevented by pretreatment of coeliac leucocytes with pronase, an enzyme that removes cytophilic antibodies. Leucocytes from healthy volunteers preincubated with serum from untreated and treated coeliac patients showed marked migration inhibition when incubated with gluten fraction III. No migration inhibition was observed with leucocytes from healthy volunteers preincubated with serum from patients with small bowel diseases other than coeliac disease and from other healthy volunteers. Untreated and treated coeliac patients who were leucocyte migration inhibition negative in the direct assay had migration indices in the sensitized range in the serum induced assay. This work is in keeping with a previous suggestion that in coeliac disease leucocyte migration inhibition induced by gluten fraction III is caused by cytophilic antibodies.

Adult↗
PubMed1989

Microleakage of mixed Class-V restorations placed with GIC-bases or dentin bonding agents.

The aim of this study was to compare the microleakage of a new generation of light-cured glass-ionomer cement bases and multistep dentin bonding agents with materials of the previous generation. Mixed class-V non-retentive cavities were prepared in freshly extracted third molars and filled with the test materials. After 250 thermocycles, the teeth were immersed in a dye solution for 48 h, sectioned longitudinally and evaluated under a stereomicroscope. The new bonding systems (i.e. Clearfil New Bond, Gluma Bond, Scotchbond 2 and Vitrabond) showed statistically significant lower microleakage values than the previous materials (i.e. Scotchbond DC, Ketac Bond, GC lining cement and 3M GIC). This in-vitro study emphasized the efficacy of the new generation of glass-ionomer cement bases and multi-step bonding agents.

Adhesives↗