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Biomedical subjects

W W Barkmeier

Publications and source records attributed to W W Barkmeier.

At least 19 recordsLinked to original sources
PubMed2001

Localized wear of compomer restorative materials.

PURPOSE: To determine and compare the localized wear of six compomer restorative materials. MATERIALS AND METHODS: Ten specimens of Dyract, Dyract AP, F2000, Compoglass F, Elan and Hytac were prepared in a custom fixture and polished. A pretest surface profile was generated using an MTS 3-D surface profilometer and the specimens were subjected to 400,000 cycles in a Leinfelder wear machine equipped with a conical stylus tip to simulate localized wear. A post-test profile was generated and the before and after profiles were fitted and analyzed using AnSur 3-D software. The total volume loss and depth of the wear facet on each specimen was calculated and statistical analysis was accomplished (ANOVA and Tukey's test). RESULTS: Volume loss (mm3) was as follows: F2000, 0.027 +/- 0.002; Hytac, 0.007 +/- 0.023; Elan, 0.054 +/- 0.013; Compoglass F, 0.135 +/- 0.006; Dyract AP, 0.135 +/- 0.023; Dyract, 0.185 +/- 0.032. Maximum depth of the wear facets (microm) was as follows: F2000, 112.2 +/- 10.2; Hytac, 132.8 +/- 9.3; Elan, 144.3 +/- 23. 1; Compoglass F, 168.3 +/- 13.0; Dyract AP, 194.0 +/- 19.7; Dyract, 220.6 +/- 15.8. There was not a difference (P > 0.05) in volumetric loss between F2000 and Hytac or between Hytac and Elan. The volume loss and maximum depth of the wear facets of F2000, Hytac and Elan was significantly less (P< 0.05) than Compoglass F, Dyract AP and Dyract The results of this study indicate that there are significant differences in the in vitro wear rates of compomer materials.

Analysis of Variance↗
PubMed2000

Approaches for intraoral repair of ceramic restorations.

Ceramic-based restorations are an important part of a dentist's armamentarium for durability and esthetics. Because of the brittle nature of ceramic materials, these restorations have the potential to fracture. Repairing ceramic-based restorations can increase the clinical longevity of failed restorations and offer the dentist and patient a cost-effective alternative to replacement. Newer porcelain repair systems show excellent adhesion durability of resin-based composites to the fractured ceramic and exposed metal surfaces. This article reviews the basic principles of ceramic repair and details the use of five intraoral porcelain repair systems.

Ceramics↗
PubMed1998

Dental adhesives in contemporary restorative dentistry.

Significant progress has been made in the area of adhesives in restorative dentistry. With respect to composite restoratives, bond strengths greater than the targeted 17 MPa are now routinely achieved by modern dentin bonding systems in laboratory tests. Each adhesive system must be handled according to the manufacturer's instructions and with careful attention to the details of application for maximal success. Clinical documentation of the success of the modern systems is limited. This especially true for the multipurpose applications often advocated by the product instructions or clinicians lecturing from personal anecdotal experience. The confirmation of laboratory results with controlled clinical trials often occurs late or not at all. A thorough understanding of the in vivo performance is needed to gain the knowledge necessary to further the technologic advances in this area.

Adhesives↗
PubMed1996

Evaluation of porcelain surface treatments and agents for composite-to-porcelain repair.

Intraoral repairs often involve bonding composite to fractured porcelain. Newer adhesive systems, currently referred to as multipurpose systems, include materials with recommended procedures for repair of porcelain. This laboratory study evaluated various treatment regimens with the ProBond adhesive system. Three different porcelain surface procedures were used: (1) air abrasion with aluminum oxide (50 microm), (2) 8% hydrofluoric acid, and (3) air abrasion and hydrofluoric acid. Eight different treatment procedures were then used to bond 10 composite cylinders to porcelain surfaces in each group. Shear bond strengths (in megapascals) were determined with an Instron testing machine after storage in water for 24 hours at 37 degrees C and after 3 months of storage and thermocycling. The combination of air abrasion and hydrofluoric acid on porcelain surfaces before bonding composite recorded the most consistently effective bond strengths. Four of the treatment regimens in the air abrasion groups yielded low bond strengths at 3 months. This study also indicated that silane treatment of porcelain is critical for development of suitable bond strengths for composite.

Air Pressure↗
PubMed1996

Bond strength of an adhesive polymerized under nitrogen.

PURPOSE: To evaluate the use of nitrogen, in conjunction with visible light polymerization, for improving composite-to-dentin bond strengths. MATERIALS AND METHODS: Composite cylinders were bonded to dentin with Scotchbond Multi-Purpose. Immediate (Groups 1-4) and 24-hour (Groups 5-8) strengths were determined for the following two adhesive application and two polymerization techniques: Groups 1 & 5: gentle air thinning of adhesive and polymerization with conventional visible light curing (VLC) unit; Groups 2 and 6: aggressive air thinning of adhesive and conventional VLC; Groups 3 and 7: gentle air thinning of adhesive and polymerization in nitrogen environment with modified VLC unit; and Groups 4 and 8: aggressive air thinning of adhesive and polymerization in nitrogen environment with modified VLC unit. RESULTS: The immediate bond strengths (MPa) were: Group 1: 15.1 +/- 1.8, Group 2: 6.1 +/- 2.1, Group 3: 17.8 +/- 3.1, Group 4: 15.8 +/- 2.0. The 24-hour strengths were: Group 5: 26.7 +/- 4.4, Group 6: 13.5 +/- 7.5, Group 7: 24.1 +/- 5.7, Group 8: 26.4 +/- 4.3. Visible light polymerization of a thinned layer of adhesive resin in a nitrogen environment produced significantly higher immediate and 24-hour bond strengths than when compared to visible light polymerization in ambient air.

Air↗
PubMed1996

Effect of low-viscosity resins on the performance of dental adhesives.

PURPOSE: To determine whether the use of low-viscosity intermediate resins (LVR) reduces microleakage of dental adhesive systems. MATERIALS AND METHODS: Wedge-shaped Class V cavities were prepared in sound extracted molars. Occlusal margins were in enamel and gingival margins were in dentin/cementum. Five adhesive systems (All-Bond 2, Clearfil Liner Bond 2, OptiBond, Prime & Bond and Scotchbond Multi-Purpose) were applied to the preparations strictly according to manufacturers' directions on one side of the tooth and with the addition of LVR (OptiBond FL Adhesive or Protect Liner F) on the other. All cavities were restored with Z100 resin composite. Specimens were then stored in water at 37 degrees C for 24 hours, thermocycled 800x, stained with silver nitrate, sectioned, and evaluated for leakage. Marginal penetration of silver nitrate was scored on 0-3 scale. RESULTS: Statistical analysis (Kruskal-Wallis non-parametric ANOVA) revealed a significant difference (P < 0.0001) in leakage at dentin margins. Multiple pairwise comparisons of control groups revealed considerable overlapping between groups, but with a trend toward less leakage by OptiBond and Clearfil Liner Bond 2. Leakage of Scotchbond Multi-Purpose was significantly reduced when Protect Liner F was used.

Analysis of Variance↗
PubMed1995

Bond strength of an adhesive resin system with various dental substrates.

A laboratory study was conducted to evaluate the Panavia 21 resin-based adhesive system as a bonding agent between a variety of dental substrates. Panavia 21 resin was bonded directly to enamel and dentin and placed between nickel-chromium-beryllium (Ni-Cr-Be) specimens and enamel, dentin, other Ni-Cr-Be samples, and type III gold. Panavia 21 resin was also used to bond amalgam to dentin. Shear bond strengths were determined at 24 hours and after thermocycling at 3 months. The results of this study at both the 24-hour and the 3-months test periods indicate that the enamel bond strengths of Panavia 21 resin (24 hours, 19.3 +/- 5.5 MPa; 3 months, 23.7 +/- 4.4 MPa) exceeded its dentin bond strengths (24 hours, 7.8 +/- 1.4 MPa; 3 months, 8.8 +/- 3.2 MPa). The bond strengths between Panavia 21 resin and Ni-Cr-Be alloy (24 hours, 16.3 +/- 3.4 MPa; 3 months, 17.6 +/- 2.7 MPa) and those for Panavia 21 resin between Ni-Cr-Be alloy and dentin (24 hours, 18.7 +/- 4.2 MPa; 3 months, 19.8 +/- 5.3 MPa) were comparable to adhesive enamel bond strengths. High bond strengths were also generated by Panavia 21 resin between Ni-Cr-Be alloy and type III gold (24 hours, 39.3 +/- 5.9 MPa; 3 months, 35.5 +/- 7.1 MPa). The greatest bond strengths observed during both test time periods for Panavia 21 resin were between Ni-Cr-Be alloy and enamel (24 hours, 54.2 +/- 10.7 MPa; 3 months, 56.4 +/- 7.1 MPa) and between two samples of Ni-Cr-Be alloy (24 hours, 55.1 +/- 5.6 MPa; 3 months, 49.1 +/- 8.6 MPa). Panavia 21 resin produced high bond strengths between a variety of dental substrates commonly used for the placement of fixed prosthodontic restorations.

Adhesives↗
PubMed1995

4-year clinical study of castable ceramic crowns.

PURPOSE: To evaluate the 4-year clinical performance of castable glass ceramic crowns used to restore teeth in the posterior segments. MATERIALS AND METHODS: 101 castable ceramic (Dicor) full++ crown restorations were placed in 61 molar and 40 premolar teeth using a bonded resin cement. RESULTS: After 4 years of clinical performance, 15 of the original 101 restorations were known to have failed with 13 of those failures affecting molar restorations. All serviceable restorations were rated as excellent for color match, margin adaptation, proximal contact and gingival health. Cavosurface margin discoloration received a 93.5% alfa response. The results of this study show that Dicor crowns meet the esthetic and biological requirements for posterior restorations. The incidence of fracture of molar restorations in this study indicated that when used for restoring molars, careful case selection and caution must be employed.

Adult↗
PubMed1995

Bond strengths and SEM evaluation of Clearfil Liner Bond 2.

PURPOSE: To evaluate a dental adhesive system that uses a single conditioning/primer agent. MATERIALS AND METHODS: Twenty-five flat enamel and dentin bonding sites were prepared to 600 grit on human molar teeth. The Clearfil Liner Bond 2 adhesive system was used to bond Clearfil AP-X composite to both enamel and dentin. After 24 hours of water storage, shear bond strengths were determined using an Instron testing machine. Fifty V-shaped cavity preparations were prepared in human molar teeth with an enamel and cementum margin. Composite restorations were placed using the new adhesive system. The teeth were stored for 24 hours, thermocycled, stained with AgNO3 , sectioned and examined for microleakage. SEM examinations were also completed to evaluate the effects of the treatment steps on enamel and dentin surfaces. RESULTS: Mean shear bond strengths for the experimental adhesive to enamel and dentin were 28.2 +/- 4.9 and 19.4 +/- 3.1 MPa. A t-test revealed that the enamel bond strength was significantly greater (P<0.05) than the dentin strength. No marginal leakage was observed from the enamel margins of the restorations. Three restorations showed minimal leakage from the cementum margins. SEM examinations showed resin penetration into both the conditioned enamel and dentin surfaces. The adhesive system produced high bond strengths to both enamel and dentin, exhibited very minimal microleakage and was easy to use.

Composite Resins↗
PubMed1994

Bond strength of a resin cement to a cured composite inlay material.

Although resin cements have been effectively bonded to mineralized tooth structures, bonding to a cured composite material has remained a challenge. This study evaluated the shear bond strength of a resin cement bonded to a cured composite inlay material by use of a variety of composite surface treatments: (1) hydrofluoric acid/60 seconds, (2) ammonium bifluoride/60 seconds, (3) resin adhesive, (4) microabrasion with 50 microns aluminum oxide, and (5) microabrasion with 50 microns aluminum oxide and application of a resin adhesive. The resin cement was also bonded to human enamel that was etched with phosphoric acid. Scanning electron microscopy examinations were completed to evaluate the effects of the composite surface treatments. The results indicated that microabrasion of a cured composite enhances bonding of a resin cement. The bond strength of a resin cement to a composite surface that was air abraded with aluminum oxide, with or without the application of a resin adhesive, was higher than surface treatments with hydrofluoric acid or ammonium bifluoride. Scanning electron microscopy indicated that an irregular surface on the composite was created with aluminum oxide air abrasion.

Acid Etching, Dental↗
PubMed1994

Effect of porcelain surface treatments on bond strengths of composite resin bonded to porcelain.

A laboratory study was conducted to evaluate the bond strength of composite resin bonded to porcelain surfaces by use of a variety of treatment regimens with the All-Bond 2 adhesive system. There were significant differences in the 24-hour bond strengths between several of the surface treatment methods. The mean shear bond strength after 24 hours of water storage ranged from 10.6 +/- 2.3 MPa to 25.0 +/- 4.4 MPa. Nine of the surface treatment methods showed a significant decrease (p < 0.05) in bond strengths after 3 months of water storage and thermocycling. After 3 months, the bond strengths ranged 0.1 +/- 0.1 MPa to 17.4 +/- 2.0 MPa. Porcelain surface treatment with aluminum oxide air abrasion followed by hydrofluoric acid, a silane coupling agent, and an unfilled resin produced a bond strength after 3 months' water storage and thermocycling that was significantly greater (p < 0.05) than the other nine porcelain surface-treatment techniques. Visual examination of the debonded specimens generally showed cohesive failures in porcelain for the treatment groups with a mean bond strength above 13 MPa.

Adhesives↗
PubMed1994

Laboratory evaluation of Amalgambond and Amalgambond Plus.

PURPOSE: To evaluate the shear bond strength (SBS) of a microfilled resin restorative material and an amalgam alloy to dentin using the Amalgambond Plus adhesive system with a variety of bonding regimens. MATERIALS AND METHODS: The study design incorporated bonding composite to both dry and moist dentin using open-ended plastic matrices and closed-ended gelatin capsules. In addition, the bond strength of amalgam to dry dentin was determined. RESULTS: The mean SBS of Silux Plus to dentin using Amalgambond without the HPA powder ranged from 17.55 +/- 1.96 MPa to 22.47 +/- 3.89 MPa. The SBS range observed when the microfilled composite was bonded to dentin with Amalgambond Plus (includes the HPA powder) was from 20.33 +/- 3.84 MPa to 22.50 +/- 3.69 MPa. There was no significant difference (P > 0.05) in the SBS of the microfilled resin restorative material to dentin between the groups that were bonded using an open-ended cylinder-shaped plastic matrix and those prepared using a closed-ended gelatin capsule matrix, nor was there a difference (P > 0.05) in the SBS when the microfilled resin restorative material was bonded to either wet or dry dentin surfaces. The use of multiple applications of Amalgambond adhesive did not markedly increase the SBS with this system. The mean bond strength of amalgam alloy (Dispersalloy) to dentin using Amalgambond Plus was 10.41 +/- 1.47 MPa.

Composite Resins↗
PubMed1994

Shear bond strength of composite to enamel and dentin using Scotchbond Multi-Purpose.

A laboratory study was conducted to determine the shear bond strength to enamel and dentin using the Scotchbond Multi-Purpose dental adhesive system. High shear bond strengths of P50 composite to both human enamel (26.8 +/- 5.2 MPa) and bovine enamel (24.8 +/- 4.1 MPa) were found when the system was used according to manufacturer's directions. The mean bond strength for human dentin (25.5 +/- 7.5 MPa) was also similar to that found for bovine dentin (23.4 +/- 4.9 MPa). Variations in the recommended application technique were examined on bovine dentin. Extreme air drying of the primer slightly reduced the mean shear bond strength (19.7 +/- 6.4 MPa), while a significant reduction was observed when the adhesive resin was aggressively air-thinned (10.1 +/- 6.6 Mpa).

Acid Etching, Dental↗
PubMed1993

Bond strength of composite resin to porcelain with newer generation porcelain repair systems.

A laboratory study was conducted to evaluate the mean shear bond strength of composite resin bonded to porcelain with the use of eight newer generation repair systems. The range of shear bond strength after 24 hours of water storage was 23.5 +/- 5.3 MPa to 12.0 +/- 2.3 MPa. After 3 months of water storage and thermocycling, the bond strength range was 20.7 +/- 1.7 MPa to 4.2 +/- 1.0 MPa. Three of eight systems evaluated did not exhibit a significant (p > 0.05) decrease in bond strength when the 24-hour bond strengths were compared with the 3-month bond strengths. Most specimens failed cohesively in the porcelain at 24 hours, but at 3 months only four of the eight systems showed consistent failures in the porcelain.

Chromium Alloys↗
PubMed1993

Shear bond strength, microleakage and scanning electron microscopy study of the Clearfil Liner Bond System.

Various adhesive systems have been introduced for enamel and dentine bonding and one of the newer systems available recently is the Clearfil Liner Bond System. This investigation was to determine the shear bond strength, evaluate the microleakage and conduct SEM examinations of this new bond system. The results showed it was possible to obtain a mean shear bond strength of 17.45 MPa to human dentine. Microleakage was minimal at the cementum/dentine margin and no microleakage was observed at the enamel margin of resin restorations placed with the system. SEM examinations revealed minimal to significant resin penetration into dentinal tubules.

Dental Bonding↗
PubMed1993

Bond strength of a veneering porcelain using newer generation adhesive systems.

A laboratory study was conducted to determine the shear bond strength of etched and silane-treated porcelain to enamel and dentin, using resin cements and newer generation adhesive systems. The results of this in vitro study showed excellent bond strength of porcelain to acid-conditioned enamel using a new adhesive system and a resin cement. The study also found strong bonds between etched and silane-treated porcelain and dentin, using several newer generation adhesive systems in conjunction with resin cements. The learning objective of this article is an increased knowledge of the newer generation adhesives with data for material comparison.

Composite Resins↗
PubMed1992

Power and time requirements for use of the argon laser to polymerize composite resins.

A carefully controlled laboratory study was conducted to determine the optimum power setting and polymerization cycle time to cure four commercially available composite resins with an argon laser. Most effective resin polymerization was achieved when Prisma APH was polymerized at 310 mW for 7 seconds, when Herculite was polymerized at 160 mW for 12 seconds, when P-50 was polymerized at 525 mW for 13 seconds and when Silux Plus was polymerized at 270 mW for 13 seconds. The exact parameters of laser power and exposure time seem to be material specific, with greater variation being noted in power setting than in exposure time.

Argon↗