Biomedical subjects

W J Finger

Publications and source records attributed to W J Finger.

At least 37 records · Page 2Linked to original sources

PubMed1996

Marginal adaptation of resin-bonded light-cured glass ionomers in dentin cavities.

PURPOSE: To investigate the marginal adaptation of resin-modified glass ionomer cements in dentin cavities placed with or without additional application of resin bonding systems. MATERIALS AND METHODS: Three resin-modified materials (Fuji II LC, Photac-Fil, Vitremer), one compomer (Dyract) and as reference an adhesively bonded resin composite system (Gluma CPS-Pekafill) were used. Flat peripheral dentin surfaces on human molar teeth were produced by wet grinding on SiC paper. Cylindrical cavities, 3.5 mm wide, were prepared in these dentin areas and restored with the individual materials. Sixty cavities were pretreated and restored as requested by the respective manufacturers. Following water storage of the specimens for 15 minutes or 24 hours, excess was gently removed by wet grinding for microscopic inspection of the marginal area. Additionally, in 30 cavities an experimental one-component adhesive resin system, a proprietary dimethacrylate and HEMA mixture dissolved in acetone, was combined with each of the restoratives for evaluation after 15-minutes water storage. Finally, in six cavities each, Dyract was combined with Prime and Bond 2.0, and Vitremer with Scotchbond Multi-Purpose Plus for assessment after 15 minutes. Maximum marginal gap widths (MGW) were measured. One-way ANOVA by ranks (Kruskal-Wallis-Test) followed by Wilcoxon's Two-Sample test were used to study the statistical difference of MGW among the treatment groups at a rejection level P = 0.05. RESULTS: Neither the conventionally placed material systems nor the restorations in combination with adhesives showed consistently gap-free margins after 15-minute water storage. After 24-hour storage with Vitremer 4 of the 6 restorations were gap-free, whereas with all other materials only perfect margins were registered. There was, however, no significant difference between the groups. Application of the experimental and/or the specific resin bonding agents had no effect on early MGW except for the Photac-Fil group, which was significantly reduced.

Analysis of Variance↗

PubMed1996

Laboratory evaluation of one-component enamel/dentin bonding agents.

PURPOSE: To evaluate the bonding efficacy of five commercial and one experimental one-component enamel/dentin adhesives. MATERIALS AND METHODS: The adhesives One-Step (BOS), Primabond (PAB), Prime & Bond 2.0 (PB2), Solist (SOL), Tenure Quik (TEQ), and an experimental compound (EXP) were investigated. The adhesives were used to bond a hybrid-type resin composite to enamel and dentin. Shear bond strength (SBS) to human teeth was determined after 24-hour storage in water. The marginal performance was evaluated on restorations in 3.5 mm wide cylindrical dentin cavities as the maximum gap width found 15 minutes after light activation. The hybrid layer thicknesses at the cavity margin were measured by light microscopy. RESULTS: Mean SBSs to enamel were between 23 and 35 MPa, those to dentin between 3.5 and 25 MPa. BOS and EXP showed the highest bond strengths to dentin and consistently gap-free restorations. PB2 mediated significantly lower SBS to dentin; only three of the six restorations were gap-free. SOL exhibited poor marginal quality (mean MGW 7.5 microns) despite 15 MPa dentin bond strength. PAB and TEQ demonstrated very low SBS to dentin. None of the restorations with these products was gap-free. All adhesives produced hybrid layers between 2 and 10 microns thick, as a coupling zone between dentin and restoration. Adhesives with the essential components of wetting monomer, well-polymerizing dimethacrylate, and acetone as the water-chasing solvent, performed very well when used with a moist bonding technique.

Acrylates↗

PubMed1995

Resin bonding efficacy of Gluma 2000 to dentine of primary teeth: an in vitro study.

The aim of this study was to investigate (i) the effect of Gluma 2000 conditioning solution on the dentine of primary teeth, (ii) the penetration of Gluma 2000 adhesive resin into the etched dentine, (iii) the shear bond strength of a composite resin restorative material (Pekafill) bonded with Gluma 2000 to dentine, and (iv) the depth of penetration of adhesive resin into the etched dentine as a function of the conditioning time. Dentine surfaces conditioned for 15, 30, 60 and 120 seconds were examined by scanning electron microscopy. The smear layer was totally removed and, with the longer conditioning times, a fine crystalline precipitation, presumably calcium oxalate, was formed. After Gluma 2000 bonding of composite resin and dissolution of the teeth the resin interface showed excellent penetration into the etched dentine. Shear bond strengths of composite resin bonded with the adhesive resin were similar following conditioning for 15, 30, 60 and 120 seconds. Microphotographs of debonded specimens indicated that the mode of failure was cohesive within the resin. The depth of penetration of resin into etched dentine was determined by scanning electron microscopy, and a linear relationship was found between the thickness of the resin-impregnated layer and conditioning time. It was therefore concluded that depth of resin penetration and shear bond strength are not correlated. The study shows that the Gluma 2000 bonding system produces reliable adhesion of composite resin to dentine of primary teeth.

Acid Etching, Dental↗

PubMed1995

Bonding of composite resin to contaminated human enamel and dentin.

PURPOSE: The purpose of this in vitro study was to evaluate the bond strengths of a bonding agent and composite resin system to human enamel and dentin treated with five contaminants (saliva, plasma, zinc oxide-eugenol cement, noneugenol zinc oxide cement, and handpiece lubricant) using air, moisture, and water as controls. MATERIALS AND METHODS: A commercial bonding agent (Gluma 2000; Bayer AG, Dormagen, Germany) and its composite (Pekafill; Bayer AG) were applied to tooth structure under two conditions (contaminated and re-etched). Samples were debonded in tension after 24 hours using an inverted, truncated cone bond test. RESULTS: Among the controls, the highest bond strengths were obtained to enamel (20 MPa) and dentin (12 MPa) with air drying. Contaminants lowered the bond strength by 20% to 100%. Re-etching without additional mechanical preparation resulted in bond strengths similar to the air control. CONCLUSIONS: Bond strength of Gluma 2000/Pekafill to tooth structure is sensitive to common forms of contamination but can be improved by re-etching after contamination occurs.

Acid Etching, Dental↗

PubMed1995

Effect of acid etchant composition and etch duration on enamel loss and resin composite bonding.

PURPOSE: To investigate the effects of different acid etchants' ability to condition enamel as gently as possible to remove a minimum of substance only, to produce a highly retentive pattern, and finally to ensure frosty appearance of the etched enamel for clinical control of the procedure. MATERIALS AND METHODS: Two commercial uni-etch gels, Gluma 2000-1 and Scotchbond Multi-Purpose Etchant, were studied together with gels of 5, 10, 20 and 35% phosphoric acid and varying amounts of thickening agents in the 20% gel. Enamel loss was measured with a contact-free method by materials and etch duration, and the shortest etching times for dull frosty enamel appearance were determined. Shear bond strength (SBS) was measured after 24 hours' storage in water. RESULTS: Enamel loss was very low with the commercial agents and increased with H3PO4 concentrations and with etch duration. While the commercial compounds produced no frosty enamel even after 120-second etch duration, the phosphoric acids produced frosted enamel after 15, 30, 60 and 120-second application of 35, 20, 10 and 5% acids, respectively. All etchants and etch durations tested produced effective retentive patterns. No differences in SBS were noted, and the failure modes were consistently cohesive in resin.

Acid Etching, Dental↗

PubMed1995

Phosphoric acid as a conditioning agent in the Gluma bonding system.

PURPOSE: To investigate the effect of phosphoric acid conditioning gels on compatibility with the Gluma dentin bonding system. MATERIALS AND METHODS: Sheer bond strengths (BS), marginal performance in dentin cavities and microleakage resistance in mixed cavities were used as target parameters to determine the efficacy of Gluma/Pekafill on dentin pretreated with conditioners of 5, 10, 20 or 35% H3PO4 and different amounts of silica (0, 5 and 10%) after 15, 30 60 or 120-second treatment duration. The thicknesses of the hybrid layers were determined along the dentin cavity margin by light microscopy. RESULTS: Neither the phosphoric acid concentration and the silica content nor the conditioning times tested had a significantly different effect on SBS or marginal performance (P > 0.05). There was no relationship between the hybrid layer thickness and the target parameters either. The SBS recorded on dentin were in the same order of magnitude as previously found on acid etched enamel (+/- 17 MPa). The marginal performance and microleakage results after thermocycling proved adequate dentin bonding and cavity sealing. Phosphoric acid etching of dentin is compatible with the gluma bonding system.

Acid Etching, Dental↗

PubMed1995

Function of the hybrid zone as a stress-absorbing layer in resin-dentin bonding.

The effects of dentinal surface conditioning with phosphoric acid or with phosphoric acid and subsequent deproteinization by sodium hypochlorite on resin bonding are presented. Bond strengths mediated by the Gluma/Pekafill bonding and restorative system were not affected by the alternative pretreatment methods, while marginal performance of restorations in dentinal cavities was significantly adversely affected by the deproteinization procedure. The resin polymer coupling zone has an important function as a layer that compensates for the curing stresses of the restorative material that act in a wall-to-wall direction.

Acid Etching, Dental↗

PubMed1994

Effects of the setting stage on the accuracy of double-mix impressions made with addition-curing silicone.

This study investigated the accuracy of double-mix impressions relative to the time of placing the tray impression material on preparations covered with medium-viscosity silicone. The curing kinetics of the addition-curing silicone impression materials and the accuracy of impressions were investigated. The observed kinetics showed the possibility of the appearance of elastic characteristics of the syringed material before the tray impression was placed. The accuracy of the impressions was not statistically different unless the setting reactions had progressed so that the consistencies of both the syringed and the tray impression were high. These results indicated that the double-mix impression was accurate independent of the curing kinetics of the syringed material alone.

Analysis of Variance↗

PubMed1994

The effect of etching time with Gluma 2000 conditioning solution on shear bond strength of a composite resin and on micromorphology of the enamel.

The purpose of this study was to assess the effect of etching time with Gluma 2000 conditioning agent on, first, the shear bond strength of composite resin to tooth enamel and, secondly, the micromorphology of the enamel. In the first part of the study flat enamel surfaces were prepared with 600-grit silicon carbide paper on 40 primary and 40 permanent teeth. Ten specimens of each group were etched for 15, 30, 60 or 120 seconds before applying bonding resin and restorative composite resin. After 24 hours' storage in water, the shear bond strength of each specimen was tested. Analysis of variance indicated a significant difference between the eight groups. However, the Student-Newman-Keuls test indicated that the only differences that were significant were the greater bond strengths of the 15-second primary tooth specimens compared with the 15- and 30-second permanent tooth specimens. In most cases the debonded specimens showed cohesive failure in resin close to the coupling interface. In the second part of the study the morphology of the enamel etching patterns in 96 other teeth was studied by scanning electron microscopy. The patterns were similar in primary and permanent teeth, and the longer the etching time the more pronounced was the pattern. The patterns produced in ground enamel were more uniform and predictable than those in pumiced enamel. Examination of bonded resin surfaces after dissolution of the teeth showed complete reproduction of the etched enamel surfaces, indicating excellent flow of the resin into the etched enamel.

Acid Etching, Dental↗

PubMed1994

Clinical and laboratory evaluation of adhesive restorative systems.

PURPOSE: To investigate the effectiveness of Clearfil Liner Bond, Gluma 2000, and Scotchbond Multi-Purpose when applied in combination with proprietary restorative resins in V-shaped circular cavities which were cut in incisors either centrally on the labial enamel surface (Type 1) or labially crossing the cemento-enamel junction (Type 2). MATERIALS AND METHODS: Forty teeth scheduled for extraction for periodontal reasons were treated in vivo and another 40 teeth in vitro. The in vivo restored teeth were extracted after 3 months of clinical service and the in vitro treated samples were stored in water for 1 week and thermocycled 250 times between 5 degrees C and 55 degrees C, prior to a 24-hour immersion in 0.5% fuchsin tracer solution of all specimens, sectioning and scoring interfacial dye penetration. RESULTS: ANOVA revealed no significant differences between all in vivo samples sites, all in vitro enamel sites and the apical Type 2 sites of the Gluma samples. In contrast, the apical Type 2 leakage of CLB and SMP was significantly more pronounced, although not statistically different from each other. The results of the short-term clinical performance of the three systems was moderately more favorable than the laboratory microleakage test results.

Analysis of Variance↗

PubMed1994

Relationship between degree of polymerization of resin composite and bond strength to Gluma-treated dentin.

The purpose of the present study was to investigate the relationship between shear bond strength (SBS) to dentin and degree of polymerization of resin adjacent to the coupling interface. A hybrid-type resin composite was polymerized on Gluma-treated dentin at thicknesses of 1, 2, 3 and 5 mm, respectively, with seven different light activation times (LAT) from 3 through 180 seconds. SBS of the specimens was determined 10 minutes after the end of light activation. The degree of polymerization of resin close to the dentin interface was determined by Wallace Indentation Depth (WID) of specimens polymerized under the same conditions as the SBS samples, however, separated from the dentin surface by a thin glass plate. Consistent relationships were found for SBS vs. LAT and WID vs. LAT by regression analyses (y = A+B/x). There was a strong linear correlation between SBS and WID (r = -0.93), indicating that the early bond strength to Gluma-treated dentin is a function of mechanical characteristics of resin close to the bonding interface.

Composite Resins↗

PubMed1994

Effect of filler content of restorative resins on retentive strength to acid-conditioned enamel.

In this in vitro study the retentive strength of enamel, either conventionally etched with a phosphoric acid gel or conditioned with an oxalic acid containing etching agent, was investigated. Five experimental restorative resins with filler contents between 0 and 78% by weight were polymerized on the etched enamel surfaces. In spite of the pronounced micromorphological differences of the patterns generated with the two etching agents, the bond strengths mediated were very similar. Application of an intermediate low-viscous or adhesive resin had no influence on bond strength. Exponential relationships were found between the filler content of the resins on the one hand and their flexural moduli and flexural strengths on the other. Significant exponential relations were also demonstrated between filler content and bond strength to the etched enamel surface. The linear relationship between mechanical properties of the resins and their bond strengths to etched enamel indicates that debonding occurred by cohesive failure in resin.

Acid Etching, Dental↗

PubMed1994

Effect of wettability of adhesive resins on bonding to dentin.

The purpose of this study was to investigate on human dentin the relationships between, on the one hand, the wettability of five adhesive compounds, characterized by different solubility parameters delta, and on the other, the thickness of the resin impregnated dentin layer (RIL) and the shear bond strength (SBS). Cut dentin surfaces were treated with conditioners of pH 1.25, 3.6 or 7.4. Shear bond strength was measured on 20 specimens each. RIL was determined by scanning electron microscope on specimens fractured perpendicularly to the bonding interface. When resins with delta 32, 30 or 39 (MJ1/2/m3/2) were used RILs were consistently 4 microns and 1 micron on dentin pretreated with the two acidic conditioners. No clearly measurable RIL was shown after application of the conditioner with pH 7.4, and when resins with delta-values of 20 and 25 were applied. For the same adhesive no difference in SBS was found, when applied on the differently conditioned dentin sites. Resins with delta > 30 produced significantly higher SBS than the two adhesives with smaller delta.

Analysis of Variance↗

PubMed1993

Morphology of coupling sites between bonding agents and dentine in vivo and in vitro.

In spite of the unclear relationship between in vitro and in vivo conditions, the majority of dentine bonding agent investigations are carried out in vitro. The purpose of this SEM study was to compare micromorphologically the bonding sites between dentine and seven resin bonding systems, which were applied either in vivo or in vitro on freshly cut dentine in similar locations on contralateral premolar teeth scheduled for extraction for orthodontic reasons. The morphology of the bonding sites was investigated on samples fractured perpendicularly to the bonding interface following superficial decalcification and deproteinization of the dentine. For six of the seven systems studied a resin-impregnated dentine layer was identified. This hybrid zone was very similar on specimens prepared in vivo and in vitro.

Adolescent↗

PubMed1993

Influence of aluminum oxalate solutions acidity and conditioning times on resin bond strength to enamel.

The present investigation demonstrated that variations in pH between 0.8 and 2.1 and in the duration of etching with an aluminum oxalate/glycine conditioning solution between 5 and 120 seconds has no influence on the retentive strength of restorative polymer to enamel, although the micromorphological appearance of enamel is clearly affected. The lower the pH of and the longer the etching time with the conditioning solution, the more pronounced is the roughness pattern generated. SEM inspection of the fracture sites following debonding of shear bond strength specimens verified consistently cohesive failure in resin close to the interface.

Acid Etching, Dental↗

PubMed1992

Marginal leakage of a new adhesive restorative system: a preliminary in vivo investigation.

The efficacy of newly developed adhesive restorative materials is commonly described by in vitro test results such as bond strength and microleakage data. Due to the inconsistency often found between in vitro testing and in vivo performance, the purpose of the present investigation was to restore teeth scheduled for extraction in vivo with an experimental restorative bonding system and to evaluate the microleakage of the restorations by common laboratory techniques following extraction after 3 months of clinical service. Two restorations were placed in each of seven anterior teeth, one in the middle of the labial enamel portion and the other labially extending over the cementoenamel junction (CEJ). Six of the seven fillings completely surrounded by enamel showed no microleakage. However, two of the restorations crossing the CEJ revealed microleakage originating from the cervical margins. In spite of the small number of fillings assessed, the experimental enamel-dentin adhesive compound tested is preliminarily considered a promising new system.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1992

Effect on dentinal adhesives on marginal adaptation and cavity sealing with resin restorations in vitro.

In a companion article in this issue and a previous article in this journal, two experimental enamel dentin adhesive systems were evaluated and compared with four commercially available resin bonding agents by SEM investigation of the tooth adhesive interfaces and by determination of bond strengths to enamel and dentin under various conditions. In continuation of these screening investigations, the present article describes the results of cavity tests for assessment of marginal adaptation by measurement of gap dimensions, and of cavity sealing by rating of microleakage, when standardized dentin cavities were treated with the adhesive restorative systems. Both tests resulted in the same ranking of the six materials. Gluma, Clearfil Photo Bond, and two experimental compounds showed very narrow gaps and moderate microleakage. In contrast, Prisma Universal Bond 2 (the material has been replaced in the market by Prisma Universal Bond 3) and Scotchbond 2 showed significantly wider marginal gaps and more pronounced microleakage. Final discrimination between the efficacy of adhesive restorative materials by any of the currently used in vitro tests is disputable and prediction of long-term clinical performance by laboratory test data remains questionable.

Adhesives↗

PubMed1992

Comparative in vitro evaluation of recent enamel and dentin adhesive materials.

In this in vitro study, two experimental and four commercially available enamel-dentin bonding agents are characterized by shear bond strengths to human teeth following storage of the specimens for 2 minutes, 15 minutes, and 24 hours, respectively, or after stressing of the bonds by 5000 thermal cycles between 5 degrees and 55 degrees C. It is assumed that the experimental compounds are clinically adequate materials to mediate long-term retention of resin restorations placed without reliance on mechanical undercuts. The limitations of such in vitro strength data regarding clinical performance are discussed and emphasized.

Analysis of Variance↗