MDPI AG Acta Medica Okayama 2073-4360 18 7 2026 Effect of Universal Adhesives on Resin Cement–Fiber Post–Core Materials 810 EN Masao Irie Department of Biomaterials, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Masahiro Okada Department of Dental Biomaterials, Graduate School of Dentistry, Tohoku University Yukinori Maruo Department of Prosthodontics, Okayama University Kenraro Akiyama Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kumiko Yoshihara Health Research Institute, National Institute of Advanced Industrial Science and Technology Akimasa Tsujimoto Department of Operative Dentistry, School of Dentistry, Aichi Gakuin University Takuya Matsumoto Department of Biomaterials, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University This study evaluated eleven resin cements used as core build-up materials by examining the following properties: (a) push-out force between root dentin and the fiber post; (b) pull-out force between the fiber post and the core build-up material; (c) shear bond strength of the resin cement to root dentin; (d) flexural strength of the resin cement; and (e) flexural modulus of elasticity of the resin cement. The purpose of this investigation was to clarify the relationships between recently available universal adhesives, core build-up materials, resin cements, and fiber posts. All experiments were performed at two evaluation periods: after 1 day of water storage (Base) and after 20,000 thermocycles (TC 20k). For the push-out test, simulated post spaces were prepared in single-rooted human premolars. The specimens were sectioned perpendicular to the long axis into 2 mm-thick slices and then subjected to push-out testing to assess the bond strength of the dentin–resin cement–fiber post complex. No significant differences in bonding performance were found between Base and TC 20k. These findings suggest that universal adhesives used for pretreatment of multiple substrates in fiber post cementation can provide not only strong but also durable adhesion over time. No potential conflict of interest relevant to this article was reported.

MDPI AG Acta Medica Okayama 2076-3417 16 5 2026 Concentration-Dependent Synergistic Interfacial Interactions Between Multifunctional Acrylate and Silane Coupling Agents in an Organic–Inorganic Nanohybrid Material 2339 EN Yukinori Maruo Department of Prosthodontics, Okayama University Kumiko Yoshihara Health Research Institute, National Institute of Advanced Industrial Science and Technology Masao Irie Department of Biomaterials, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Noriyuki Nagaoka Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University Naoki Kodama Department of Prosthodontics, Okayama University Mai Yoshizane Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kentaro Akiyama Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Synergistic effects of a multifunctional acrylate and a long-chain silane coupling agent were investigated in an organic–inorganic nanohybrid material. We tested the bond strength of nanohybrid composites treated with experimental primers containing silane coupling agents―3-methacryloxypropyl trimethoxysilane (γ-MPTS) or 8-methacryloxyoctyl trimethoxysilane (8-MOTS)―with or without multifunctional acrylates―trimethylolpropane triacrylate (A-TMPT) or dipentaerythritol hexaacrylate (A-DPH). Shear bond strength was evaluated after 24 h of water storage at 37 °C. Untreated control and silane-only groups exhibited low shear bond strengths (e.g., control: 2.4 ± 2.0 MPa) and failed exclusively at the adhesive interface. While addition of A-TMPT did not significantly improve bond strength, addition of A-DPH produced significantly higher shear bond strengths. Highest strength was achieved with 30% 8-MOTS and A-DPH (22.4 ± 6.1 MPa), followed by 20% γ-MPTS and A-DPH (19.0 ± 7.0 MPa), and A-DPH groups produced cohesive failures. Regardless of the silane used (γ-MPTS or 8-MOTS), incorporating A-DPH in the primer consistently yielded superior bond strengths, indicating a promising strategy for improved adhesion for such nanohybrid systems. These findings provide new insights into optimizing resin–filler interfacial interactions and may contribute to the development of restorative materials with improved long-term clinical durability. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1996-1944 18 9 2025 Initial Bonding Performance to CAD/CAM Restorative Materials: The Impact of Stepwise Concentration Variation in 8-Methacryloxyoctyl Trimethoxy Silane and 3-Methacryloxypropyl Trimethoxy Silane on Feldspathic Ceramic, Lithium Disilicate Glass-Ceramic, and Polymer-Infiltrated Ceramic 1983 EN Yukinori Maruo Department of Prosthodontics, Okayama University Miho Kuwahara Department of Occlusal and Oral Functional Rehabilitation, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kumiko Yoshihara Health Research Institute, National Institute of Advanced Industrial Science and Technology Masao Irie Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Noriyuki Nagaoka Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School Mai Yoshizane Department of Occlusal and Oral Functional Rehabilitation, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takuya Matsumoto Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kentaro Akiyama Department of Occlusal and Oral Functional Rehabilitation, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences This study investigated the effects of varying concentrations of two distinct silane agents, 8-methacryloxyoctyl trimethoxy silane (8-MOTS) and 3-methacryloxypropyl trimethoxy silane (γ-MPTS), on their initial bonding efficacy to feldspathic ceramic (FC), lithium disilicate glass-ceramic (LD) and polymer-infiltrated ceramic (PIC) specimens, in 10% increments for concentrations ranging from 10% to 40%. Shear bond strengths between the ceramic substrates and the luting material were assessed following 24 h incubation in distilled water. For FC, the median value of shear bond strength peaked at 20% of γ-MPTS (7.4 MPa), while 8-MOTS exhibited a concentration-dependent increase, reaching its highest value at 40% (13.1 MPa). For LD, γ-MPTS above 10% yielded similar strength median values (10.2 MPa), whereas 8-MOTS at 30% (15.8 MPa) and 40% (13.4 MPa) yielded higher strength values than at 10% (2.9 MPa) and 20% (4.1 MPa), with the highest median value exhibited at 30%. For PIC, both γ-MPTS and 8-MOTS demonstrated similarly low bond strength values which were not significantly different from the non-silane-treated specimens. When applied on silica-based FC and LD, silane revealed a concentration-dependent bonding effect, with 8-MOTS exhibiting superior bond strength to γ-MPTS. However, PIC, characterized by a high inorganic filler content, demonstrated limited bondability with both silanes. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2073-4360 16 16 2024 Long-Term Bonding Performance of One-Bottle vs. Two-Bottle Bonding Agents to Lithium Disilicate Ceramics 2266 EN Masao Irie Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masahiro Okada Department of Dental Biomaterials, Tohoku University Graduate School of Dentistry Yukinori Maruo Department of Prosthodontics, Okayama University Hospital Goro Nishigawa Department of Prosthodontics, Okayama University Hospital Takuya Matsumoto Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences The aim of this study was to compare the long-term bonding performance to lithium disilicate (LDS) ceramic between one-bottle and two-bottle bonding agents. Bonding performance was investigated under these LDS pretreatment conditions: with hydrofluoric acid (HF) only, without HF, with a two-bottle bonding agent (Tokuyama Universal Bond II) only. Shear bond strengths between LDS and nine resin cements (both self-adhesive and conventional adhesive types) were measured at three time periods: after one-day water storage (Base), and after 5000 and 20,000 thermocycles (TC 5k and TC 20k respectively). Difference in degradation between one- and two-bottle bonding agents containing the silane coupling agent was compared by high-performance liquid chromatography. With HF pretreatment, bond strengths were not significantly different among the three time periods for each resin cement. Without HF, ESTECEM II and Super-Bond Universal showed significantly higher values than others at TC 5k and TC 20k when treated with the recommended bonding agents, especially at TC 20k. Difference in degradation between one- and two-bottle bonding agents containing the silane coupling agent was compared by high-performance liquid chromatography (HPLC). For both cements, these values at TC 20k were also not significantly different from pretreatment with only Tokuyama Universal Bond II. For LDS, long-term bond durability could be maintained by pretreatment with Tokuyama Universal Bond II instead of the hazardous HF. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2073-4360 15 5 2023 Shear Bond Strength of Resin Luting Materials to Lithium Disilicate Ceramic: Correlation between Flexural Strength and Modulus of Elasticity 1128 EN Masao Irie Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Masahiro Okada Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Yukinori Maruo Department of Prosthodontics, Division of Dentistry, Okayama University Goro Nishigawa Department of Prosthodontics, Division of Dentistry, Okayama University Takuya Matsumoto Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science This study investigates the effect of the curing mode (dual-cure vs. self-cure) of resin cements (four self-adhesive and seven conventional cements) on their flexural strength and flexural modulus of elasticity, alongside their shear bond strength to lithium disilicate ceramics (LDS). The study aims to determine the relationship between the bond strength and LDS, and the flexural strength and flexural modulus of elasticity of resin cements. Twelve conventional or adhesive and self-adhesive resin cements were tested. The manufacturer's recommended pretreating agents were used where indicated. The shear bond strengths to LDS and the flexural strength and flexural modulus of elasticity of the cement were measured immediately after setting, after one day of storage in distilled water at 37 degrees C, and after 20,000 thermocycles (TC 20k). The relationship between the bond strength to LDS, flexural strength, and flexural modulus of elasticity of resin cements was investigated using a multiple linear regression analysis. For all resin cements, the shear bond strength, flexural strength, and flexural modulus of elasticity were lowest immediately after setting. A clear and significant difference between dual-curing and self-curing modes was observed in all resin cements immediately after setting, except for ResiCem EX. Regardless of the difference of the core-mode condition of all resin cements, flexural strengths were correlated with the LDS surface upon shear bond strengths (R-2 = 0.24, n = 69, p < 0.001) and the flexural modulus of elasticity was correlated with them (R-2 = 0.14, n = 69, p < 0.001). Multiple linear regression analyses revealed that the shear bond strength was 17.877 + 0.166, the flexural strength was 0.643, and the flexural modulus was (R-2 = 0.51, n = 69, p < 0.001). The flexural strength or flexural modulus of elasticity may be used to predict the bond strength of resin cements to LDS. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1996-1944 15 21 2022 Does Multifunctional Acrylate's Addition to Methacrylate Improve Its Flexural Properties and Bond Ability to CAD/CAM PMMA Block? 7564 EN Yukinori Maruo Department of Prosthodontics, Okayama University Kumiko Yoshihara Health Research Institute, National Institute of Advanced Industrial Science and Technology Masao Irie Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Noriyuki Nagaoka Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School Takuya Matsumoto Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Shogo Minagi Department of Prosthodontics, Okayama University This study investigated the effects of a multifunctional acrylate copolymer-Trimethylolpropane Triacrylate (TMPTA) and Di-pentaerythritol Polyacrylate (A-DPH)-on the mechanical properties of chemically polymerized acrylic resin and its bond strength to a CAD/CAM polymethyl methacrylate (PMMA) disk. The methyl methacrylate (MMA) samples were doped with one of the following comonomers: TMPTA, A-DPH, or Trimethylolpropane Trimethacrylate (TMPTMA). The doping ratio ranged from 10 wt% to 50 wt% in 10 wt% increments. The flexural strength (FS) and modulus (FM) of PMMA with and without comonomer doping, as well as the shear bond strength (SBS) between the comonomer-doped PMMA and CAD/CAM PMMA disk, were evaluated. The highest FS (93.2 +/- 4.2 MPa) was obtained when doped with 20 wt% of TMPTA. For TMPTMA, the FS decreased with the increase in the doping ratio. For SBS, TMPTA showed almost constant values (ranging from 7.0 to 8.2 MPa) regardless of the doping amount, and A-DPH peaked at 10 wt% doping (8.7 +/- 2.2 MPa). TMPTMA showed two peaks at 10 wt% (7.2 +/- 2.6 MPa) and 40 wt% (6.5 +/- 2.3 MPa). Regarding the failure mode, TMPTMA showed mostly adhesive failure between the CAD/CAM PMMA disk and acrylic resin while TMPTA and A-DPH showed an increased rate of cohesive or mixed failures. Acrylate's addition as a comonomer to PMMA provided improved mechanical properties and bond strength to the CAD/CAM PMMA disk. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2504-477X 5 10 2021 Flexural Property of a Composite Biomaterial in Three Applications 282 EN Masao Irie Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Yukinori Maruo Department of Occlusion and Removable Prosthodontics, Okayama University Hospital Goro Nishigawa Department of Occlusion and Removable Prosthodontics, Okayama University Hospital Takuya Matsumoto Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Resin composite is widely used in the dental field in clinics as a biomaterial. For example, it has been used as a composite material, a type of biomaterial, to repair caries and restore masticatory function, and as a luting agent to adhere the restoration to the tooth substrate. In order to demonstrate its function, we have measured the mechanical strength. From such basic research, we explain the potential of a dental material through the measurement of flexural strength and modulus of elasticity. In this research, we introduce commercial products that are actually used as composite materials suitable for tooth substrate and provide readers with their properties based on flexural strength and modulus of elasticity. In clinical performance, it might be advisable to delay polishing when a composite material is used for a luting material, a filling material and a core build-up material, as the flexural strength and the flexural modulus of elasticity were improved after 1 day of storage, and flexural strength and characteristics are considered as important mechanical properties of oral biomaterials. No potential conflict of interest relevant to this article was reported.

SAGE Publications Acta Medica Okayama 2280-8000 18 2020 Flexural properties, bond ability, and crystallographic phase of highly translucent multi-layered zirconia 2280800020942717 EN Yukinori Maruo Department of Occlusion and Removable Prosthodontics, Okayama University Kumiko Yoshihara National Institute of Advanced Industrial Science and Technology, Health Research Institute Masao Irie Department of Biomaterials, Okayama University Goro Nishigawa Department of Occlusion and Removable Prosthodontics Noriyuki Nagaoka Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Takuya Matsumoto Department of Biomaterials, Okayama University Shogo Minagi Advanced Research Center for Oral and Craniofacial Sciences, Okayama University This study investigated the mechanical properties, bond ability, and crystallographic forms of different sites in a highly translucent, multi-layered zirconia disk. Flexural properties, bond ability to resin cement, and phase composition were investigated at three sites of a highly translucent, multi-layered zirconia disk: incisal, middle, and cervical. Flexural strength (FS) and flexural modulus (FM) were measured with static three-point flexural test. Shear bond strength (SB) to resin cement was measured after 24 h storage (37°C). Phase composition under mechanical stress was analyzed using X-ray diffraction. Without air abrasion, FS at the incisal site yielded the lowest value and was significantly lower than the middle and cervical sites. Air abrasion lowered the FS of each site. FM at the incisal site without air abrasion showed the significantly lowest value, and air abrasion increased its FM value. At the middle and cervical sites, their FM values were higher than the incisal site but were not significantly affected by air abrasion. SB value did not show significant differences among the sites. After sintering, cubic zirconia was detected at each site. Rhombohedral phase transformation occurred after mirror polishing. In highly translucent, multi-layered zirconia which was mainly composed of cubic zirconia, rhombohedral phase transformation occurred under mechanical stress and resulted in weakened mechanical properties. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2073-4360 12 12 2020 Flexural Strength of Resin Core Build-Up Materials: Correlation to Root Dentin Shear Bond Strength and Pull-Out Force 2947 EN Masao Irie Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Yukinori Maruo Department of Occlusion and Removable Prosthodontics, Okayama University Goro Nishigawa Department of Occlusion and Removable Prosthodontics, Okayama University Kumiko Yoshihara National Institute of Advanced Industrial Science and Technology (AIST), Health and Medical Research Institute Takuya Matsumoto Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science The aims of this study were to investigate the effects of root dentin shear bond strength and pull-out force of resin core build-up materials on flexural strength immediately after setting, after one-day water storage, and after 20,000 thermocycles. Eight core build-up and three luting materials were investigated, using 10 specimens (n = 10) per subgroup. At three time periods-immediately after setting, after one-day water storage, and after 20,000 thermocycles, shear bond strengths to root dentin and pull-out forces were measured. Flexural strengths were measured using a 3-point bending test. For all core build-up and luting materials, the mean data of flexural strength, shear bond strength and pull-out force were the lowest immediately after setting. After one-day storage, almost all the materials yielded their highest results. A weak, but statistically significant, correlation was found between flexural strength and shear bond strength (r = 0.508, p = 0.0026, n = 33). As the pull-out force increased, the flexural strength of core build-up materials also increased (r = 0.398, p = 0.0218, n = 33). Multiple linear regression analyses were conducted using these three independent factors of flexural strength, pull-out force and root dentin shear bond strength, which showed this relationship: Flexural strength = 3.264 x Shear bond strength + 1.533 x Pull out force + 10.870, p = 0.002). For all the 11 core build-up and luting materials investigated immediately after setting, after one-day storage and after 20,000 thermocycles, their shear bond strengths to root dentin and pull-out forces were correlated to the flexural strength in core build-up materials. It was concluded that the flexural strength results of the core build-up material be used in research and quality control for the predictor of the shear bond strength to the root dentin and the retentive force of the post. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 22 9 2006 Immediate versus water-storage performance of Class V flowable composite restoratives 875 883 EN Masao Irie Kenji Hatanaka Kazuomi Suzuki David C. Watts Objectives The aims of this investigation were to clarify the effects of 24 h water-storage and finishing time on mechanical properties and marginal adaptation to a Class V cavity of eight modern flowable resin-composites. Methods Eight flowable composites, plus two controls (one microfilled and one hybrid composite), were investigated with specimen sub-groups (n = 10) for each property measured. The principal series of experiments was conducted in model Class V cavities with interfacial polishing either immediately (3 min) after setting or after 24 h water-storage. After the finishing procedure, each tooth was sectioned in a buccolingual direction through the center of the restoration, and the presence or absence of marginal-gaps was measured (and then summed for each cavity) at 14 points (each 0.5 mm apart) along the cavity restoration interface (n = 10 per group; total points measured = 140). The shear bond-strengths to enamel and to dentin, and flexural strengths and moduli data were also measured at 3 min and after 24 h water-storage. Results For all flowable composites, polished immediately after setting, 14–30 summed gaps were observed (controls: 64 and 42). For specimens polished after 24 h, a significantly (p < 0.05) reduced number of 8–17 summed gaps occurred for only 3 flowable composites; whereas for 5 flowable composites there were non-significantly-different (p > 0.05) numbers (11–17) of summed gaps (controls: 28 and 22). After 24 h storage, shear bond-strengths to enamel and to dentin, flexural strengths and moduli increased highly significantly (p < 0.001) for all materials, except Silux Plus. Significance A post-cure interval of 24 h resulted in enhanced mechanical and adhesive properties of flowable dental composites. In a minority of cases there was also a reduced incidence of marginal-gap formation. However the latter effect may be partly attributed to 24 h delayed polishing, even though such a delay is not usual clinical practice. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 22 5 2005 Root-surface gap-formation with RMGIC restorations minimized by reduced P/L ratio of the first increment and delayed polishing 486 497 EN Masao Irie Rosalina Tjandrawinata Kazuomi Suzuki David C. Watts Objectives This in vitro study evaluated the effect on interfacial gap-formation around resin-modified glass–ionomer (RMGIC) root surface restorations with (a) variations in powder/liquid ratio (P/L) of the first increment of an incremental procedure, compared with a bulk restoration technique, and (b) delayed versus immediate polishing, to permit maturation. Methods Cavity preparations were placed in premolar teeth on upper facial root surfaces. Two RMGICs were studied (Fuji II LC and Vitremer), with their associated conditioner or primer, applied with an incremental technique. The P/L ratio of the first increment was reduced to fractional (normalized) values between 0.2 and 1.0 of the manufacturers' recommended P/L, and the manufacturers' P/L was used for the second increment. Control groups were bulk filled. After polishing, either: (i) immediately after light-activation or (ii) after 24 h storage, the restored teeth were sectioned in a buccolingual direction through the center of the restoration and the presence or absence of marginal gaps was measured at ×1000 magnification at 14 points (each 0.5-mm apart) along the cavity restoration interface; (n=10; total points measured per group=140). Results For both RMGICs, significant differences (p<0.05) in gap-incidence were observed between polishing (i) immediately and (ii) after one-day storage. In the former case, 30–70 gaps were found, with or without the incremental technique. In the latter case, only 2–14 gaps were observed. With fluid mixes (normalized P/L ratios between 0.3 and 0.6) for the first increment, gap-formation was greatly reduced, especially with Fuji II LC. Significance To minimize gap formation, more fluid mixes could be used especially with Fuji II LC to give improved adaptation to the dentin. Secondly, whenever possible, polishing should be delayed on the final increment to permit maturation and minimize mechanical disruption of both increments. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 33 2 2008 Class I Gap-formation in Highly-viscous Glass-ionomer Restorations: Delayed vs Immediate Polishing 196 202 EN Masao Irie Yukinori Maruo Goro Nishgawa Kazuomi Suzuki David C Watts This in vitro study evaluated the effects of delayed versus immediate polishing to permit maturation of interfacial gap-formation around highly viscous conventional glass-ionomer cement (HV-GIC) in Class I restorations, together with determining the associated mechanical properties. Cavity preparations were made on the occlusal surfaces of premolars. Three HV-GICs (Fuji IX GP, GlasIonomer FX-II and Ketac Molar) and one conventional glass-ionomer cement (C-GIC, Fuji II, as a control) were studied, with specimen subgroups (n=10) for each property measured. After polishing, either immediately (six minutes) after setting or after 24 hours storage, the restored teeth were sectioned in a mesiodistal direction through the center of the model Class I restorations. The presence or absence of interfacial-gaps was measured at 1000× magnification at 14 points (each 0.5-mm apart) along the cavity restoration interface (n=10; total points measured per group = 140). Marginal gaps were similarly measured in Teflon molds as swelling data, together with shear-bond-strength to enamel and dentin, flexural strength and moduli. For three HV-GICs and one C-GIC, significant differences (p<0.05) in gap-incidence were observed between polishing immediately and after one-day storage. In the former case, 80–100 gaps were found. In the latter case, only 9–21 gaps were observed. For all materials, their shear-bond-strengths, flexural strength and moduli increased significantly after 24-hour storage. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 20 9 2004 Immediate performance of self-etching versus system adhesives with multiple light-activated restoratives 873 880 EN Masao Irie Kazuomi Suzuki David C. Watts Objectives: The purpose of this study was to evaluate the performance of both single and double applications of (Adper Prompt L-Pop) self-etching dental adhesive, when used with three classes of light-activated restorative materials, in comparison to the performance of each restorative system adhesive. Evaluation parameters to be considered for the adhesive systems were (a) immediate marginal adaptation (or gap formation) in tooth cavities, (b) free setting shrinkage-strain determined by the immediate marginal gap-width in a non-bonding Teflon cavity, and (c) their immediate shear bond-strengths to enamel and to dentin. Methods: The maximum marginal gap-width and the opposing-width (if any) in the tooth cavities and in the Teflon cavities were measured immediately (3 min) after light-activation. The shear bond-strengths to enamel and to dentin were also measured at 3 min. Results: For light-activated restorative materials during early setting (<3 min), application of Adper Prompt L-Pop exhibited generally superior marginal adaptation to most system adhesives. But there was no additional benefit from double application. The marginal-gaps in tooth cavities and the marginal-gaps in Teflon cavities were highly correlated (r=0.86–0.89, p<0.02–0.01). For enamel and dentin shear bond-strengths, there were no significant differences between single and double applications, for all materials tested except Toughwell and Z 250 with enamel. Significance: Single application of a self-etch adhesive was a feasible and beneficial alternative to system adhesives for several classes of restorative. Marginal gap-widths in tooth cavities correlated more strongly with free shrinkage-strain magnitudes than with bond-strengths to tooth structure. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 20 1 2004 Marginal and flexural integrity of three classes of luting cement, with early finishing and water storage 3 11 EN Masao Irie Kazuomi Suzuki David C. Watts Objectives. The aims of this investigation were to clarify the effects of finishing-time and 24 h water-storage on mechanical properties and marginal adaptation to dentin of seven modern luting cements, representing three chemical types. Methods. Bistite II, Chemiace II, Compolute, XenoCem, PermaCem, Fuji Cem and Fuji Plus were investigated with specimen sub-groups (N=10) for each property measured. The principal series of experiments was conducted in dentin cavities with interfacial polishing either immediately (3 min) after setting or after 24 h water-storage. After the finishing procedure, the maximum marginal gap width and the opposing width (if any) per cavity were measured microscopically, and summed. Then the overall sum of gap-widths (per group; N=10) was calculated. Marginal gaps were similarly measured in Teflon cavities, together with shear-bond-strengths to dentin and early flexural strengths, moduli and swelling data. Results. For specimen-sets polished immediately after setting, summed marginal gaps of 23–121 μm were observed, for all luting cements except Compolute. A significantly different (p<0.05) result of either no gap or 6–28 μm summed gap-widths occurred in specimens polished after 24 h. For all materials, their shear-bond-strengths, flexural strength and moduli significantly increased after 24 h storage. Significance. The marginal behavior can be interpreted in terms of the contributions of bonding, shrinkage, swelling and compliance of components, along with compositional features of the cements. With these types of cement it is generally inadvisable to polish the interfacial luting surface immediately after cementing. The polishing procedures should be carried out not less than 24 h later. One resin-cement was able to withstand immediate finishing. No potential conflict of interest relevant to this article was reported.