By means of X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC), this study set out to investigate the application of plasma immersion ion implantation (PIII) for the surface modification of ProTaper^® NiTi rotary instruments. This study was undertaken because the PIII method was perceived to have the potential of developing into a standard surface modification technique that improves clinical quality and outcome. Specimens received nitrogen ion or nitrogen plus argon ion implantation. XPS analyses with and without argon ion etching were obtained for all specimens. In addition, DSC analysis was performed to investigate the phase transformation behavior of the bulk material. Results indicated that the surfaces of NiTi instruments were successfully modified by nitrogen PIII, whereby a light golden TiN layer was yielded. Moreover, the PIII technique did not alter the superelastic character of NiTi instruments because it was carried out at near-room temperature. We thus concluded that nitrogen PIII is a promising surface modification technique to improve the surface characteristics of NiTi rotary instruments.

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The objective of this study was to evaluate the effects of triethylene glycol (TEG) and triethylene glycol monomethacrylate (TEGMA) solutions as dentin primers on dentin bonding. To this end, wall-to-wall polymerization contraction gap width of a resin composite in a cylindrical dentin cavity and shear bond strength to a flat dentin surface were measured. Dentin was pretreated with an experimental dentin bonding system—consisting of 0.5 M ethylenediaminetetraacetic acid conditioner, TEG or TEGMA primer, and Clearfil Photo Bond bonding agent—prior to resin composite filling. When the cavity was primed with an aqueous solution of 35 vol% TEG, 35 or 45 vol% TEGMA for a few seconds, contraction gap formation was prevented completely. Then, among these three gap-free groups, there were no significant differences in shear bond strength. It was thus shown that both TEG and TEGMA were highly effective dentin primers, completely preventing contraction gap formation even when they were applied for only a few seconds.

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This study was designed to examine the effects of dose of recombinant human BMP-2 (rhBMP-2) on bone formation at palatal sites in 10-week-old (10w) and 70-week-old (70w) rats, when combined with a polylactate-polyglycolate copolymer/gelatine sponge (PGS).
New bone formation was observed at six weeks after implantation. In the 10w rats, thickness of new bone (TNB) increased as the dosage increased from 0 μg to 4 μg, and decreased significantly as the dosage increased from 8 μg to 24 μg. In contrast, in the 70w rats, TNB increased as the dosage increased from 0 μg to 16 μg, and did not significantly change as the dosage increased from 16 μg to 24 μg.
These results suggest that the most effective dosage of rhBMP-2 for induction of bone formation varies according to age.

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We have previously reported that an osteopontin-derived SVVYGLR peptide exhibited potent angiogenic activity in vitro and in vivo. In the present study, the focus points were on the in vitro effect of SVVYGLR on bone marrow stromal cell proliferation, as well as its in vivo effect on bone tissue formation when grafts made of CO₃Ap-collagen sponge—as a scaffold biomaterial containing the SVVYGLR motif—were implanted. SVVYGLR peptide promoted bone marrow stromal cell proliferation. When a CO₃Ap-collagen sponge containing SVVYGLR peptide was implanted as a graft into a tissue defect created in rat tibia, the migration of numerous vascular endothelial cells—as well as prominent angiogenesis—inside the graft could be detected after one week. These results thus suggested that our scaffold biomaterials including the peptide could be useful for bone tissue regeneration.

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Biomechanical properties of bonded dentin are important for resin restorations. We hypothesized that there are no differences in the hardness and elasticity of sound and caries-affected primary dentin bonded with a one-step self-etch adhesive. Resin-dentin interfaces in sound and caries-affected primary dentin were measured with a nano-indentation tester and observed with SEM and TEM. Interfacial dentin hardness was similar for sound and caries-affected dentin, but significantly lower than the underlying intact dentin. As for the Young's modulus of interfacial dentin, both substrates exhibited significantly lower values than the subsurface dentin. Further, the Young's modulus of interfacial dentin was significantly lower in caries-affected dentin. TEM revealed extensive interfacial nanoleakage in bonded sound dentin, while it was minimal in bonded caries-affected dentin. However, in the latter, silver deposits were identified within the porous substrate. Shorter application time and/or improvement of the adhesive components may be required to obtain stable adhesion in primary dentin.

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This study examined the effects of monomer composition, original filler content, and application of centrifugal force on the resulting filler loading of composites. Either Bis-MPEPP or UDMA was mixed with TEGDMA at a molar ratio of 1: 1. Silane-treated silica (14-20 wt%) was added to each mixture. After the mixtures were centrifuged and light-polymerized, rate of increase was determined as the filler increment of 2.0-mm-high, disk-shaped sections of specimen when compared against the uncentrifuged filler content. Both the original filler loading and monomer composition influenced the filler content of the centrifuged composites. Fillers in Bis-MPEPP-based composites exhibited a higher rate of condensation after application of centrifugal force than did UDMA-based composites. The results were suggestive of underlying relationships among the composition, component stability, and post-polymerization properties of flowable composites.

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This study was designed to evaluate the efficacy of resin coating on the regional microtensile bond strength (MTBS) of a resin cement to the dentin walls of Class II cavities. Twenty mesio-occlusal cavities were prepared in human molars. In 10 cavities, a resin coating consisting of a self-etching primer bonding system, Clearfil SE Bond, and a low-viscosity microfilled resin, Protect Liner F, was applied. The other 10 teeth served as a non-coating group. After impression taking and temporization, they were kept in water for one day. Composite inlays were then cemented with a dual-cure resin cement, Panavia F 2.0, and stored in water for one day. Thereafter, MTBSs were measured. Two-way ANOVA (p=0.05) revealed that the MTBS of resin cement to dentin was influenced by resin coating, but not by regional difference. In conclusion, application of a resin coating to the dentin surface significantly improved the MTBS in indirect restorations.

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The aim of this study was to develop an effective primer to improve the adhesive property between all kinds of dental metal alloy and resin cement. To this end, we synthesized N,N'-dimethacryloylcystine (NDMCC) which had both disulfide functional group (to improve adhesion between precious metal alloy and resin) and carboxyl group (to improve adhesion between non-precious metal alloy and resin). With the presence of SuperBond C&B, the adhesion between precious, semi-precious, and non-precious dental metal alloys and resin cement was improved when compared to the untreated controls. However, the adhesive property between all types of dental metal alloy and resin cement was not improved with Panavia 21EX. In particular, reduced bond strength in the case of non-precious metal alloy was speculated to arise from the acid-base neutralization reaction between the carboxyl group of NDMCC and the amine present in the polymerization initiator system of Panavia 21EX.

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Resin coating technique is a unique method that improves the dentin bond strength of resin cements in indirect restorations. However, the weak link of a specimen bonded using the resin coating technique was reported to be the bonded interface between the resin coating material and resin cement. The purpose of this study, therefore, was to enhance the bonding performance between a resin coating material and a resin cement. Two light-cured flowable composites, Protect Liner F and Clearfil Flow FX, were used as coating materials, and two dual-cure composite materials, Panavia F 2.0 and Clearfil DC Core Automix, were used as resin cements. The ultimate tensile strength of each material and the microtensile bond strengths of the bonded specimens of resin coating material and resin cement were measured using a crosshead speed of 1.0 mm/min. Three-way ANOVA (p=0.05) revealed that the highest microtensile bond strength was obtained using a combination of Clearfil Flow FX and Clearfil DC Core Automix, and when the surface of the coating material was treated with ED Primer II. It was strongly suggested that materials with a higher ultimate tensile strength, when used in both resin coating and cementation, could enhance the bond strength between the two.

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With a view to comparing conventional (CGIC) and resin-modified glass ionomer cements (RMGIC) in terms of mechanical properties, these materials were subjected to different loading conditions for evaluation. In addition, this study investigated the assumption that capsulated systems possess superior mechanical properties compared to the hand-mixed systems, owing to the former's better material homogeneity and a more precise adjustment of the powder-liquid ratio.
In view of the aims of this study, the following mechanical properties were determined: strength and modulus of elasticity in flexural test, diametric tensile and compressive strengths, as well as variation of hardness and modulus of elasticity with depth.
In all macroscopic strength tests, the RMGICs performed significantly better than the CGICs. In microhardness evaluation, the differences were levelled out. In particular, the mechanical properties of RMGICs were comparable to those of microfilled and packable composites.
The effect of mixing was closely intertwined with material property. The tested CGICs performed better when they were hand-mixed, whereas RMGICs fared better in the capsulated form.

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The purpose of this study was to investigate the effects of different cross-sectional shapes and presence of taper on stress distribution in clasp arms made of glass fiber-reinforced composite (FRC) material. Stress analysis of clasps was performed under a constant load (5 N) using a three-dimensional finite element method with due consideration to the anisotropy of unidirectional FRC material. Results were then compared with clasp arms made of metal—an isotropic material. It was found that both FRC clasps and metal clasps yielded similar results. As for the displacement of clasp arms with a basic cross-sectional shape under a load of 5 N, the amount of displacement showed that FRC clasps provided sufficient retentive force required for clinical application.

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The purpose of this study was to evaluate the effects of four different ratios of silanized mica filler and milled glass fiber on the surface hardness of an acrylic denture tooth material. Acrylic resin disks made of polymethyl methacrylate (PMMA) used in fabrication of denture teeth were used as the control group. Eight test groups were prepared by adding a ratio of 5%, 10%, 15%, or 20% by weight of silane-treated mica filler or milled glass fibers to the PMMA resin of denture teeth. Surface hardness test was performed for each group. There were statistically significant differences in surface hardness between the control group and 5%, 10%, and 15% mica- and glass-containing test groups (p<0.05). It was determined that addition of 5%, 10%, and 15% of silane-treated mica filler or silane-treated milled glass fiber to the PMMA resin of denture teeth resulted in significantly improved surface hardness.

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The purpose of this study was to determine the optimal condition for fabricating accurate crowns efficiently using an internet-based CAD/CAM system. The influences of three different CAD/CAM restorative materials (titanium, porcelain, and composite resin) and three different step-over scanning distances (0.01 mm, 0.11 mm, and 0.21 mm) were evaluated, and their interactive effects were carefully examined.
Several points on the inner and outer surfaces of machined crowns—as well as height—were measured. These measurements were then compared with the original models, from which machining accuracy was obtained. At all measuring points, the inner surface of all crowns was machined larger than the die model, whereas the cervical area of porcelain crown was machined smaller than the crown model. Results of this study revealed that a step-over distance of 0.11 mm was an optimal scanning condition, taking into consideration the interactive effects of scanning time required, data volume, and machining accuracy.

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Tooth movements produced by a canine retraction spring were calculated. Although a gable bend and an anti-rotational bend were incorporated into the spring, the canine tipped and rotated initially. Retraction force decreased and moment-to-force ratio increased after the spring legs closed. Then, the initial tipping and rotation began to be corrected. As a result, the canine moved almost bodily after a prolonged period of time. Such tooth movements cannot be estimated from the initial force system. The gable bend decreased tipping movement, but increased rotational movement. On the other hand, the anti-rotational bend decreased rotational movement but increased tipping movement. In other words, one bend decreased the effect of the other, when both bends were incorporated in the spring.

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To reduce the leachability of reducing agents from composite resins, immobilization of a simulated reducing agent at the surface of SiO₂ fillers was examined. SiO₂ plates were immersed in 2% 3-aminopropyltriethoxy silane/ethanol solution, and then immersed in dimethyl sulfoxide with 0.25 wt% 4-dimethyl amino benzoic acid (DMABA), 2.0 wt% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, and 0.5 wt% N-hydroxysuccinimide. Wide-scan spectrum of X-ray photoelectron spectroscopy did not detect carbon contamination. However, narrow scan detected an O=C-N peak at 399.8 eV, suggesting that DMABA could be immobilized on silane-coupled SiO₂ plates. Further, surface plasmon resonance analysis indicated the adsorption of MMA at the surface of reducing agent-immobilized plate.

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The purpose of this study was to evaluate the microshear bond strength and bond durability between ceramic and two dualcured resin luting agents irradiated by different light intensities. Ceramic specimens were bonded with two resin bonding systems: Ceramic Primer and Linkmax HV (CP/LMHV) and Monobond S and Variolink IIHV (MBS/VLIIHV), and were either irradiated by 800, 310, 160, 80, and 40 mW/cm² light or not irradiated. Bond strength was measured after 24-hour water storage at 37°C and after subsequent 10,000 times of thermal cycling. Failure modes were determined by stereomicroscopy. After 24-hour water storage, there were no significant differences among the various irradiation conditions for both MBS/VLIIHV and CP/LMHV. However, regardless of light intensity, MBS/VLIIHV showed higher bond strength than CP/VLIIHV at each thermal cycling, except for no irradiation condition at 10,000 thermal cycles. In conclusion, thermal cycling significantly reduced the bond strength for all groups.

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To prevent enamel lesions from further demineralization, a complete and homogeneous penetration of low-viscosity resins (‘infiltrants’) should be accomplished. With commercially available adhesives, this goal might not be achieved because of their penetration capabilities. On this note, the Penetration Coefficient (PC) describes the penetrativity of liquids and might be employed to develop optimal infiltrants. Thus, the aim of this study was to compare the penetration abilities of 12 experimental infiltrants (BisGMA/TEGDMA comonomers showing varying PCs) with a commercially available adhesive (Excite, Vivadent). In each of the 156 bovine enamel specimens, four subsurface lesions were created. Three of the four lesions were infiltrated with either the adhesive or one of 12 experimental resins for either 10, 22, or 40 seconds, and subsequently light-cured. Specimens were studied using confocal microscopy and penetration depths were determined. A good correlation between PC and penetration depth was thereby observed (Pearson's correlation coefficient, r=0.820).

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By means of Weibull analysis, this study evaluated and compared the flexural strength and shear bond strength of flowable light-cured composites against those of conventional ones. Twenty specimens of each material were prepared for flexural and shear bond strength measurements. Specimens were measured after water storage at 37°C for 24 hours. Three of four flowable composites showed significantly higher flexural strength than conventional ones, with Weibull moduli ranging between 6 and 14. With the presence of a bonding agent, the shear bond strength to enamel of both types was not different significantly (p=0.28), with Weibull moduli ranging between 4 and 9. In the selection of an excellent resin composite material, results of this study showed that a high, stable Weibull modulus value could be a sound indicator.

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The purpose of this study was to examine all-ceramic crowns for internal defects using micro-focus X-ray computed tomography (microCT). Mono-ceramic CAD/CAM crowns, ceramic-core CAD/CAM crowns, and heat-pressed ceramic crowns were used as specimens. The microCT images of the specimens were obtained and analyzed using a 3D volume rendering software.
Mono-ceramic CAD/CAM crowns contained almost no pores, while ceramic-core CAD/CAM crowns contained pores only in the porcelain veneer area. Heat-pressed ceramic crowns had lots of pores in the cusps and the area around them.
Results of this study indicated that internal pores in all-ceramic crowns could be observed non-destructively using microCT, and that CAD/CAM all-ceramic crowns contained fewer pores than crowns fabricated using manual techniques.

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This study was a clinical trial of a one-step, total priming and bonding system, Xeno III. Thirty restorations were placed in minimally invasive V-shaped, Class V cervical cavities. Immediately after placement, baseline records were made after restorations were assessed using modified Ryge/USPHS criteria. Subsequently, restorations were evaluated at recall intervals up to 18 months. Additionally, the measurement of tensile bond strength and the FE-SEM observation of resin-tooth interface were performed in vitro. At 18 months, all restorations were classified as clinically satisfactory and assigned with an Alpha rating. Tensile bond strength of Xeno III was not significantly different from that of Clearfil SE Bond. Resin-enamel/dentin interface was very tight, with the presence of a very thin hybrid layer at the superficial dentin. Based on the results obtained, the Xeno III resin bonding system seemed promising as a one-step, self-etch adhesive.

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