Search PubMed⌕ Search

Biomedical subjects

W W Barkmeier

Publications and source records attributed to W W Barkmeier.

At least 19 recordsLinked to original sources
PubMed1992

Laboratory evaluation of adhesive systems.

Adhesive bonding of resin materials to acid-conditioned enamel is a clinically proven technique in preventative, restorative, and orthodontic procedures. Laboratory evaluations of etched-enamel resin bonding have shown excellent bond strengths and the virtual elimination of marginal microleakage. Adhesion to dentin has been more of a challenge. Earlier-generation dentin bonding systems did not yield high bond strengths in the laboratory or prevent marginal microleakage. Newer-generation adhesive systems generally use a dentin conditioner to modify or remove the smear layer and a subsequent application of an adhesive resin bonding agent. Laboratory evaluations of newer systems have shown bond strengths that approach or actually exceed that of etched enamel resin bonding. Bond strengths have improved with the evolution of dentin bonding systems, and microleakage from the cementum/dentin margin has been significantly reduced or prevented with the newer systems. Although laboratory testing of adhesive systems provides a mechanism to screen and compare newly developed systems, clinical trials are essential to document long-term clinical performance.

Adhesives↗
PubMed1992

Scanning electronic microscopic analysis of the local effects of a periodontal scaling gel on selected surfaces.

A laboratory study was conducted to evaluate the effects of a periodontal scaling gel on mineralized tooth surfaces and selected dental restorative materials. SofScale Scaling Gel (Ash/Dentsply) was applied on enamel and dentin surfaces of freshly extracted human teeth. These surfaces were evaluated before and after a gel treatment. The gel was also applied to glass ceramic, amalgam, hybrid composite, feldspathic porcelain, glass ionomer, gold alloy, silver palladium alloy, and non-precious alloy. The contact times with these materials and substances ranged from two minutes to sixteen hours. Scanning electron microscopy (SEM) was employed to evaluate differences between treated and control surfaces. Intact enamel and dentin surfaces appeared cleaner without obvious morphological changes with gel contact times up to twelve minutes. When treated for sixteen hours, the enamel exhibited an etch pattern characteristic of a surface treated for sixty seconds with 37% phosphoric acid. No morphological changes were observed on the surface of the restorative materials evaluated with contact times up to twelve minutes. Scanning electron microscopy indicates that SofScale Scaling Gel does not alter the morphological structure of restorative materials, intact enamel and dentin with gel contact times up to twelve minutes.

Cellulose↗
PubMed1992

A clinical evaluation of the effects of a periodontal scaling gel.

This research evaluated the in vivo effects of a periodontal scaling gel used in routine prophylaxis. Fifteen adult patients with moderate to heavy calculus were selected for full mouth hand scaling and prophylaxis using a split mouth design, employing SofScale Scaling Gel in experimental quadrants. Patients and operators were asked to evaluate differences between control and treated quadrants. The following parameters were evaluated during and after treatment: Gingival effects, tooth sensitivity, ease of calculus removal, and overall patient comfort. In addition pre- and post-treatment tooth surfaces were evaluated with scanning electron microscopy using a replicate technique. No tooth sensitivity or soft tissue irritation was observed in any control or experimental quadrants. Calculus removal was independently judged by operators to be easier in the gel treated quadrants when compared to untreated control quadrants. Scanning electron microscopy revealed cleaner enamel and root surfaces with no obvious morphological changes in mineralized tissues. The results of this study demonstrate the safety of the scaling gel and the increased effectiveness of calculus removal during hand scaling of teeth treated with this gel.

Adult↗
PubMed1991

Post polymerization strength values of an argon laser cured resin.

A hybrid composite resin, Prisma APH, and a microfilled composite resin, Silux Plus, were compared regarding diametral tensile strength values following conventional visible light polymerization and argon lasing. The time interval between resin polymerization and physical property testing ranged from 1 hour to 20 days. Results demonstrated considerable mean tensile strength value variation in the earlier phases of the study with a lessening of the differences between the tensile strengths achieved by each method of polymerization as the 20 day interval was approached. It was concluded that composite resin testing protocols should be lengthened to be able to fully assess the effects of the widely variant, time dependent mean test results.

Argon↗
PubMed1991

Dentinal bond strengths and microleakage of a 4-META adhesive to amalgam and composite resin.

A 4-META-containing adhesive was evaluated for its ability to bond a composite resin and two types of amalgam to dentin. One group of composite resin was tested after 24 hours and another group after 24 hours of thermocycling. Shear bond strengths were: composite resin at 24 hours = 22.38 MPa; thermocycled composite resin = 20.86 MPa; spherical alloy = 3.38 MPa; admixed alloy = 3.84 MPa. Microleakage was evaluated after the 4-META adhesive was applied to cavity preparations and compared to that of a group treated with a cavity varnish. There was statistically significantly less microleakage in the 4-META group at both the occlusal and gingival margins.

Coloring Agents↗
PubMed1991

Degree of composite resin polymerization with visible light and argon laser.

A study was conducted to compare the degree of resin polymerization achievable using conventional visible light techniques and argon lasing. High performance liquid chromatography was used to extract unpolymerized resin from microfilled and small particle composite resin samples following photoactivation with visible light and the argon laser. It was determined that a significantly greater degree of microfilled resin polymerization was achievable following argon lasing compared to exposure to conventional visible light techniques. Although the small particle composite resin samples were polymerized as well as, or slightly better, with the argon laser, the differences were found to be insignificant. As a result, the argon laser should be considered a potentially advantageous method of initiating the polymerization of dental composite resin restorations.

Argon↗
PubMed1991

Dentinal shear bond strength, microleakage, and contraction gap of visible light-polymerized liners/bases.

The bond strength and microleakage patterns of three light-curing glass-ionomer cement liners/bases (Vitrebond, XR Ionomer, and Zionomer) were evaluated and compared to a fluoride-releasing resin (TimeLine) designed for the same use. Bond strength tests were performed at 24 hours and 7 days. At 24 hours Vitrebond, Time-Line, and Zionomer had statistically significantly greater bond strengths than XR Ionomer. At 7 days, Vitrebond had a statistically significantly stronger bond than the others. Microleakage was evaluated after 24 hours of thermocycling. Vitrebond and XR Ionomer had statistically significantly less leakage than the others, while TimeLine had significantly more leakage than the others. Polymerization contraction gaps between the liners/bases and dentin were examined with scanning electron microscopy. Contraction gaps were approximately 10 microns with Vitrebond and XR Ionomer and 5 microns with TimeLine. A contraction gap generally was not observed with Zionomer.

Dental Bonding↗
PubMed1991

Current status of adhesive resin systems.

The advanced third-generation bonding agents have created excitement as they have the potential to develop effective dentin bonding. These materials have shown better bond strengths and less marginal microleakage than the previous generations of adhesives. Enamel acid etching and the new primer/adhesive systems can enhance the retention rates of resin restorations and reduce or eliminate marginal microleakage.

Adhesives↗
PubMed1989

Enhancement of physical properties of resin restorative materials by laser polymerization.

A study was conducted to compare the compressive strength, diametral tensile strength, transverse flexural strength, and flexural modulus of a microfilled and a small particle composite resin restorative material following argon laser and conventional visible light polymerization techniques. All physical properties examined in this study were enhanced by laser polymerization. The diametral tensile strength of both types of restorative materials was significantly greater following laser polymerization, as were the transverse flexural strength and the flexural modulus of the microfilled resin restorative material. Additionally, these results were obtained with a laser polymerization time that was one-fourth that used for visible light activation. It was concluded that the argon laser is a potentially advantageous means of initiating the polymerization of dental composite resin restorations.

Acrylic Resins↗
PubMed1989

Shear bond strength, microleakage and SEM study of the XR Bond adhesive system.

A new resin dentin adhesive consisting of a primer (phosphonate dimethacrylate) and bonding agent (phosphonated BIS-GMA) was evaluated with bond strength tests, marginal microleakage studies, and SEM examination. The mean bond strength to dentin was 15.6 +/- 3.7 MPa. Microleakage studies found no marginal leakage at the enamel cavosurface margin and very minimal microleakage at the dentin/cementum margins. SEM examination showed that the primer was very effective in modifying the smear layer.

Acrylates↗
PubMed1989

Fluoride release from orthodontic adhesives.

Two commercial orthodontic adhesives containing fluoride were evaluated in vitro for fluoride release. Fluoride release is critical in preventing both decalcification around orthodontic brackets and the formation of white spot lesions. A paste-type adhesive composite resin and a glass ionomer luting agent were compared to a glass ionomer restorative material to determine fluoride release. The composite resin adhesive released minimal fluoride for only three days and then ceased. The glass ionomer adhesive released fluoride at a similar rate to the glass ionomer restorative material with fluoride release still evident at three months.

Composite Resins↗
PubMed1989

Shear bond strength of the Tenure Solution dentin bonding system.

A liquid solution of an oxalate bonding system containing NTG-GMA and PMDM has become commercially available. The bond strength of this oxalate adhesive (Tenure Solution) to dentin was determined by bonding composite resin cylinders to extracted teeth. The bond strengths obtained in this study are compared to the bond strengths obtained in earlier studies with the first and second generation oxalate adhesives whose components were supplied as powders and required mixing. The oxalate solutions developed significantly higher bond strengths than the original powder type systems.

Composite Resins↗
PubMed1988

Assessing composite resin wear in primary molars: four-year findings.

Many investigators have reported minimal wear of resin restorations in primary molars. Until recently, quantitative wear assessments have not been reported. The purpose of this investigation was (1) to present and contrast data from two 48-month clinical trials wherein quantitative wear assessments were used to evaluate wear of resin restorations in primary molars, and (2) to compare these results with those using the USPHS method of wear assessment. The data were collected from two different clinical trials. One was conducted at the University of California in San Francisco by Tonn and Ryge (TR Trial). The other was conducted at the University of North Carolina at Chapel Hill by Oldenburg, Vann, and Dilley (OVD Trial). The OVD Trial had a sample size of 45 patients with 106 restorations; the TR Trial had 44 patients with 96 restorations. The restorations in both trials were Class I and II restorations in occlusion. They were placed with the experimental light-cured posterior composite resin F-70, later marketed as Ful-Fill. At baseline, six, 12, 24, 36, and 48 months, restorations were evaluated by two evaluators trained in USPHS criteria as well as by a quantitative method of wear assessment, the standard cast technique as described by Leinfelder. Interstudy comparisons were made by Chi-square tests (USPHS evaluations) and ANOVA (quantitative assessments). The results showed that resin restorations in primary molars exhibited progressive wear with time in service. The rate and quantity of wear were very similar to those seen in permanent posterior teeth over 36 months. Findings agree with previous reports that the USPHS evaluation criteria are insensitive in detecting early wear in primary molars.

Bisphenol A-Glycidyl Methacrylate↗