W W Barkmeier’s research while affiliated with University of Nebraska at Omaha and other places

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Publications (254)


Figure 3. The correlation of volume and max depth.
Results for localized wear of light-cure resin luting cements.
Results of Pearson correlation analysis for each material.
Wear Resistance of Light-Cure Resin Luting Cements for Ceramic Veneers
  • Article
  • Full-text available

December 2024

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19 Reads

Journal of Functional Biomaterials

Miyuki Oshika

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Takafumi Kishimoto

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[...]

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The purpose of this study was to compare the wear resistance of light-cure resin luting cements for veneers with that of other luting materials investigated in earlier studies. An Alabama wear-testing machine was used to measure the wear resistance of four recent light-cure resin luting cements for veneers (G-Cem Veneer; Panavia V5 LC; RelyX Veneer Cement; and Vario-link Esthetic LC). The volume loss ranged from 0.027 ± 0.003 to 0.119 ± 0.030 mm3, the mean facet depth from 56.053 ± 7.074 to 81.531 ± 7.712 µm, and the maximum facet depth from 100.439 ± 26.534 to 215.958 ± 27.320 µm. G-Cem Veneer showed significantly better (p < 0.05) wear resistance than the other materials tested. Representative SEM images were obtained which showed differences in form among the wear facets for the luting cements examined. Correlations were calculated between the three measurements for each material, and the pattern of correlations was also different for each material.

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Comparing Various Resin Luting Cement Systems in Different Etching Modes Through Bond Durability and Morphological Features

February 2024

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294 Reads

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8 Citations

Operative Dentistry

Objectives This study aimed to investigate bond performance of various resin luting cement (RLC) systems on enamel and dentin in different etching modes and to compare the RLC-tooth interface morphology using scanning electron microscopy (SEM). Methods and Materials The self-adhesive RLC systems used in combination with universal adhesives were as follows: Scotchbond Universal Adhesive Plus + RelyX Universal (3M Oral Care) and Clearfil Universal Bond Quick ER + SA Luting Multi (Kuraray Noritake Dental). These RLC systems were also used alone as self-adhesive RLC systems without universal adhesives (self-adhesive mode). The conventional RLC systems for comparison materials were as follows: BeautiBond Xtream + ResiCem EX (Shofu) and Tooth Primer + Panavia V5 (Kuraray Noritake Dental). Twelve specimens were prepared for each group to measure shear bond strength (SBS) in different etching modes. A stainless-steel rod was used as a substitute for indirect restorations. Bonded specimens were allocated to baseline (stored for 24 hours) and artificially aged (thermocycling [TC] for 10,000 cycles) groups. Representative treated tooth surfaces and RLC-tooth interfaces were observed using SEM. Results Three-way analysis of variance (ANOVA) revealed that all the factors (etching mode, storage period, and RLC system) had a significant influence on the enamel SBS values (p<0.05). Enamel SBS was significantly higher in etch-&-rinse (ER) mode than in self-etch (SE) mode, regardless of RLC system or storage period. Three-way ANOVA showed that all the factors had a significant influence on the dentin SBS values (p<0.001). Most RLC systems showed significantly higher dentin SBS in SE mode than in ER mode, regardless of storage period. However, the combination with Scotchbond Universal Adhesive Plus and RelyX Universal showed no significant difference in SBS values between etching modes at the baseline and showed a significantly higher SBS value in ER mode than in SE mode after TC. Conclusions The self-adhesive RLC systems with universal adhesives tended to show higher enamel and dentin bond performance than the self-adhesive RLC systems alone. The morphology of treated tooth surfaces and resin cement-tooth interfaces were dependent on the RLC system and etching mode used. The RLC systems with primer application showed a thin, high-density layer above the intact dentin in both etching modes, suggesting chemical interaction.


Scanning electron microscopy observation of dentin bond interfaces in different types of resin luting cements

January 2024

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36 Reads

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4 Citations

Dental Materials Journal

This study aimed to observe and compare the resin luting cement (RLC)/dentin interfaces of different types of RLC systems with scanning electron microscopy (SEM). This study evaluated six self-adhesive resin luting cement systems (SARLCs), four systems combining a SARLC with a tooth primer (SARLCPs), and six conventional resin luting cement systems (CVRLCs). Cured resin composite rods were bonded to bovine dentin using RLCs in different etching modes. The morphological features at the interfaces were observed using SEM. Although all RLCs in etch-&-rinse (ER) mode showed a clear hybrid layer, most SARLCs had a thinner and more porous hybrid layer than the SARLCPs and CVRLCs. All SARLCPs with primer and CVRLCs showed a thin high-density layer below the primer layer in both etching modes. CVRLCs and SARLCPs with primer treatment systems may be more versatile and reliable when compared to simplified RLC systems.


Bond durability of a two-step adhesive with a universal-adhesive-derived primer in different etching modes under different degradation conditions

January 2023

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171 Reads

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9 Citations

Dental Materials Journal

This study investigated the enamel and dentin bond durability of a two-step adhesive system, using a universal adhesive-derived primer (G2-Bond Universal [GU]), and compared it with the two conventional, two-step, self-etch adhesive systems (Clearfil SE Bond 2 [CS] and OptiBond XTR [OX]) under thermal cycling (TC) and long-term water storage (WS). The shear bond strengths to bovine enamel and dentin were determined using the etch-and-rinse and self-etch modes. Twelve specimens per test group were prepared and further divided into the following subgroups: 1) subjected to TC, 2) long-term WS, and 3) WS for 24 h (baseline). The enamel and dentin bond durability of GU was superior to those of CS and OX in different etching modes and under different degradation conditions. The latest two-step adhesive system, which utilizes universal adhesives’ benefits in its primer, might offer durable clinical bonding performances and can be widely used in a clinical setting.



Early Phase Enamel Bond Performance of a Two-step Adhesive Containing a Primer Derived from a Universal Adhesive

November 2022

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333 Reads

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8 Citations

Purpose: To investigate the changes in the enamel bond performance of a two-step adhesive containing a primer derived from a universal adhesive in the early phase before 24 h and compare them to those of other adhesives. The Knoop hardness number (KHN) of the cured adhesive layers and resin composite was measured. Materials and methods: A new two-step adhesive using universal adhesive technology, G2-Bond Universal, was tested. Two conventional two-step adhesives, Clearfil SE Bond 2 and OptiBond eXTRa, and an established universal adhesive, Scotchbond Universal Plus Adhesive, were used as comparison materials. Twelve specimens per group were used to measure the shear bond strength (SBS) to bovine enamel in different etching modes. The bonded specimens were stored in distilled water at 37°C for 5 min or 1, 6, 12, or 24 h before SBS testing. The KHN of the adhesive layer and resin composite was determined after the same storage periods as for SBS testing. Results: All adhesives exhibited increased SBS with prolonged storage periods, irrespective of the etching mode. The KHN of the adhesive layer and resin composite increased over time. Conclusions: There were strong positive correlations between the SBS and KHN of the adhesive layer and resin composite. Phosphoric acid pre-etching of enamel effectively increases enamel bond performance. The two-step adhesive G2-Bond Universal demonstrated significantly higher bond strength in the early phase than the other adhesives in self-etch mode.


Fig. 1. Fatigue bond strength testing set-up with ACTA Fatigue Tester (Academic Center for Dentistry Amsterdam, Amsterdam, Netherlands).
Fig. 2. Fatigue bond strength testing set-up with Four-station Fatigue Cycler (Prototech, Portland, OR, USA).
Fig. 3. Fatigue bond strength testing set-up with MTS 858 Mini Bionix II Servo Hydraulic System (MTS Systems Corporation, Eden Prairie, MN, USA).
Fig. 5. The results for fatigue bond strength of 3-and 2-step etch-and-rinse (E&R) adhesive systems and universal adhesives in E&R mode to enamel and dentin.
Fig. 14. Scanning electron microscopy (SEM) observations of hybrid layer for 3-and 2-step etch-and-rinse (E&R) adhesive systems and universal adhesive in E&R mode. D: dentin; HL: hybrid layer.
Fatigue bond strength of dental adhesive systems: Historical background of test methodology, clinical considerations and future perspectives

November 2022

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507 Reads

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14 Citations

Japanese Dental Science Review

Numerous laboratory evaluations have been conducted since Dr. Rafael Bowen introduced a method for determining the bond strengths of adhesive systems to dental substrates in 1965. Most of the past studies have been conducted using static bond strength tests, such as shear and tensile bond strength testing with either macro or micro sized specimens. These static bond strength tests are conducted using a monotonically increasing load in which stress is applied continuously until failure occurs. Although the type of stress that develops in static bond strength tests is not typically encountered in clinical situations, over the years clinicians have based their choice of adhesive systems for use in daily practice on the results of such tests. However, some well-known researchers have reported that the results obtained from static bond strength testing may have limited clinical relevance and should not be used only by themselves to make recommendations for clinical use. In clinical situations, restorations undergo cyclic stress during mastication at stress levels well below the breaking stress used in static bond strength tests. Thus, dynamic bond strength tests, using cyclic loading, should be more clinically relevant than static bond strength tests. Over 15 years, a testing method designed to assess fatigue bond strengths of dental adhesive systems has been developed through inter-collegial and international collaborative efforts. This review discusses the development of fatigue bond strength testing methodology, provides both a historical perspective and current information regarding available testing data for all categories of adhesive systems to enamel and dentin and perspectives on the future development of both adhesive systems and testing methods.


Figure 1. Figure 1. Atomic force microscopy images of milled and polished chairside CAD/CAM provisional restorations. (a) milled restorations of artBloc Temp; (b) milled restorations of Telio
CAD; (c) milled restorations of Vita CAD-Temp; (d) CA polished restorations of artBloc Temp; (e) CA polished restorations of Telio CAD; (f) CA polished restorations of Vita CAD-Temp; (g) KU polished restorations of artBloc Temp; (h) KU polished
restorations of Telio CAD; (i) KU polished restorations of Vita CAD-Temp; (j) KP polished restorations of artBloc Temp; (k) KP polished restorations of Telio CAD; (l) KP polished restorations of Vita CAD-Temp.
Table 1. Materials used in this study.
Table 2. Table 2: Surface Roughness (Ra) of Milled and Polished Chairside CAD/CAM Provisional Restorations Measured Using Optical Profilometer.
Table 3. Table 3: Surface Roughness (Ra) of Milled and Polished Chairside CAD/CAM Provisional Restorations Measured Using Atomic Force Microscopy.
Table 4. Faculty Member and Graduate Student (16 Dentists) Assessment of Chairside CAD/CAM Provisional Restorations for Visual Ranking and Clinical Acceptability Scores.
Effectiveness of Different Polishing Kits for Chairside CAD/CAM Provisional Restorative Materials

October 2022

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111 Reads

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4 Citations

Operative Dentistry

Objective: To investigate the efficacy of three specially designed polishing kits for provisional restorations made from three chairside computer-aided design and computer-aided manufacturing (CAD/CAM) provisional resin block. Method: Ninety-six chairside CAD/CAM provisional restorations were milled out of three chairside CAD/CAM provisional resin blocks: (1) ArtBloc Temp (Merz Dental); (2) Telio CAD (Ivoclar Vivadent); and (3) Vita CAD-Temp (VITA Zahnfabrik). The provisional restorations for each material were allocated into the following groups: (1) milled restorations (no polish); (2) polished with CADMaster CAD/CAM Adjustment & Polishing Kit (CM, Shofu); (3) polished with KUT Ultimate Bisacryl (Temporaries) Polishing Kit (KU, Dental Savings Club); and (4) polished with K0330 PMMA Adjusting, Finishing & Polishing (KP, Brasseler USA). Optical profilometry and atomic force microscopy (AFM) were used to assess the surface roughness (Ra) of each provisional restoration at the microscale and nanoscale, respectively, and obtain topographical images. In addition, the milled and polished restorations were visually evaluated by 16 dentists. Results: There was a strong positive correlation with Ra values between optical profilometry and AFM. Only KP significantly improved the surface roughness of CAD/CAM provisional restorations compared to the milled equivalent, regardless of material type or measurement modality (ie, lateral length scale). Although surface topography imaging with AFM revealed some shallow scratches, even for KP polished specimens, all KP polished restorations were categorized as clinically acceptable for provisional restorations in visual inspections from dentists. Conclusion: Specially designed polishing kits for provisional restorations did not all improve the surface roughness of chairside CAD/CAM provisional restorations, regardless of the measurement method. KP was more consistently effective in polishing milled chairside CAD/CAM provisional restorations than CM and KU.


Citations (92)


... According to the manufacturer [17,18], SBU+ has several advantages over its predecessor, including dual-and self-cure compatibility without the need for an additional dual-cure activator, no need to light cure the adhesive when it is combined with the corresponding dualcured resin-based cement from the same manufacturer, a crosslinking radiopaque monomer that does not contain Bis-GMA (bisphenol A-glycidyl methacrylate), and a longer silane chain that eliminates the need for a separate primer when luting ceramic restorations. Several laboratory studies have described the adhesion characteristics of SBU+ to enamel and dentin [19][20][21]. However, RCT with SBU+ have not been reported in the peer-reviewed literature. ...

Reference:

Prospective, randomized clinical trial evaluating the clinical performance of a new universal adhesive in Class I and Class II restorations at 1 year
Effect of different pretreatment agents on intact or ground enamel bond performance of different types of adhesive systems
  • Citing Article
  • June 2024

International Journal of Adhesion and Adhesives

... The luting resin tested seems to have sufficient resistance against hydrolysis and thermocycling during the tested time interval. Also, in other studies 49,56 no significant bond strength differences were reported with the same luting resin. However, bond strength to dentin was investigated 49 or the thermocycling method differed from the present study. ...

Comparing Various Resin Luting Cement Systems in Different Etching Modes Through Bond Durability and Morphological Features

Operative Dentistry

... Two-step self-etch adhesive systems include of a seperate primer and bonding agent 13,14,40 . Primer treatment in either etching mode before cementation may induce chemical interaction because of functional monomers reaching the intact dentin through the smear layer or the hybrid layer 41 . Most studies 21,24-26 using Er: YAG laser treatment reported that bond strength of two-step self-etch adhesive systems on dentin was better than that of etch-rinse adhesive systems. ...

Scanning electron microscopy observation of dentin bond interfaces in different types of resin luting cements
  • Citing Article
  • January 2024

Dental Materials Journal

... No significant decrease in bond strength was observed at TC10,000 in any of the groups. Matsui et al. reported a significant decrease at 5,000 cycles for Clearfil SE Bond 25) , but for CSE2, the µTBS does not decrease even when tested under bovine tooth storage conditions for one year 36) , thermal cycling 20,000 times 10) , 50,000 times 37,38) . This stability is likely due to the improved polymerization by CSE2 which contains new polymerization initiators and the formation of more stable hybrid layer and bond layer 39) . ...

Bond durability of a two-step adhesive with a universal-adhesive-derived primer in different etching modes under different degradation conditions

Dental Materials Journal

... According to the manufacturer [17,18], SBU+ has several advantages over its predecessor, including dual-and self-cure compatibility without the need for an additional dual-cure activator, no need to light cure the adhesive when it is combined with the corresponding dualcured resin-based cement from the same manufacturer, a crosslinking radiopaque monomer that does not contain Bis-GMA (bisphenol A-glycidyl methacrylate), and a longer silane chain that eliminates the need for a separate primer when luting ceramic restorations. Several laboratory studies have described the adhesion characteristics of SBU+ to enamel and dentin [19][20][21]. However, RCT with SBU+ have not been reported in the peer-reviewed literature. ...

Early Phase Enamel Bond Performance of a Two-step Adhesive Containing a Primer Derived from a Universal Adhesive

... However, provisional restorations are susceptible to bacterial retention and colonization owing to biomaterial surface properties, such as roughness, contact area and electrical charges that facilitate microbial adhesion and growth [11][12][13][14]. In addition, microbial communities within the oral cavity vary with more than 700 bacterial species and exist mainly as biofilms on teeth, dentures and mucosal surfaces [15,16]. ...

Effectiveness of Different Polishing Kits for Chairside CAD/CAM Provisional Restorative Materials
  • Citing Article
  • October 2022

Operative Dentistry

... Although Kuraray released Clearfil SE Bond (Kuraray Noritake Dental, Tokyo, Japan) in 1991 which is considered the gold standard in this category, it did not reveal about the adhesive's component or the discovery of 10-MDP. After Kuraray's patent on 10-MDP expired, 3M Oral Care launched Scotchbond Universal Adhesive in 2013 and since then many manufacturers have followed and developed universal adhesive systems [13]. Second, the systematic review by Silva et al. [4] included studies with only one type of cavity design. ...

Bond Durability of Two-Step HEMA-Free Universal Adhesive

Journal of Functional Biomaterials

... The resin-based composite (RBC) embodies the concept of minimal intervention dentistry, which has been refined since its initial proposal by FDI in 2002, and materials have been developed by applying the results of basic research to clinical practice [1]. Research focusing on the mechanisms of adhesion between the restorative material and the tooth substrate has led to substantial improvements in bond durability [2], which has made it possible to perform restorative treatments that balance functionality and aesthetics. ...

Fatigue bond strength of dental adhesive systems: Historical background of test methodology, clinical considerations and future perspectives

Japanese Dental Science Review

... A group of six highly filled flowable composite resins exhibited higher flexural properties and wear resistance compared to two conventional composite resin pastes [6]. Similarly, in a study of handling and mechanical properties of low viscosity composite resins, it was evident that some exhibited excellent flexural properties and wear resistance [10]. When the effects of acidic beverages on the surface roughness, microhardness, flexural strength and elastic modules were evaluated for a microhybrid, bulk-fill and injectable composites, it was evident that the highly filled "injectable" exhibited the highest mean flexural strength values and, interestingly, when exposed to short-and long-term immersion cycles it exhibited a flexural strength value above ISO 4049/2019 standards [11], which is promising for clinical use [12]. ...

Handling and Mechanical Properties of Low-viscosity Bulk-fill Resin Composites
  • Citing Article
  • September 2021

Operative Dentistry

... The blade method was also used to apply the shear stress [36]. However, it has shown that having the crosshead blade closer to the substrate which can effectively reduce the tensile part such as enclose-mould method [52] or Ultradent Shear bond strength test method in ISO 29,022 [53]. ...

Effect of mold enclosure and chisel design on fatigue bond strength of dental adhesive systems

European Journal Of Oral Sciences