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The aim of this study was to investigate the wear of four nanofilled resin composites using simulated toothbrushing for 50,000 cycles with calcium carbonate slurry. The depth of abrasion and roughness (Ra) were measured after each 10,000 brushing cycle. The surface texture of the worn samples was examined by SEM.The wear depths of the nanofill Filtek Supreme XT (FIL), the nanohybrides Grandio (GRA), Tetric EvoCeram (TET), and Venus Diamond (VED) increased linearly with numbers of brushing cycles or approximately 80, 12, 600, and 60 mum, respectively after 50,000 strokes. Surface roughness showed virtually no change between 10,000 and 50,000 brushing cycles; the ranking order was TET < FIL < GRA < VED. FIL showed rather uniform abrasion with nanoclusters protruding from the surface. TET was very smoothly abraded without signs of debonding of the prepolymerized particles, whereas GRA and VED showed pronounced wear of the matrix polymer surrounding larger glass filler particles.

The purpose of this in vitro investigation was to study the effects on bond strength to primed human enamel stemming from opacity and polymerization inhibition by oxygen due to two coating resins. The coating resins and primers used were White Coat and an experimental material, SIR. The bond strengths on fine-ground enamel were evaluated for three shades of each of these coating resins after 24-hour storage in water. In addition, their degrees of opacity and oxygen inhibition depths were measured. The mild self-etch primer solutions produced very shallow but distinct etching patterns for micromechanical retention of the coating resin. Significant linear relationships between bond strength on the one hand and opacity and oxygen inhibition depth on the other were found for the three shades of each coating resin. Generally, the bond strength mediated on enamel is sufficiently high when these resins are combined with their proprietary adhesives. Therefore, the decrease in bond strength with increasing opacity of the coating resin shades has to be taken into account during application and light-curing.

Molecular structures of organic films generated from mixed solutions of a l,3,5-triazine-2,4-dithione derivative (VBATDT) and a phosphate derivative (M10P) onto Au, Ag, and Cu substrates were examined by IR and Raman spectroscopy. The molecular structure varies according to the concentration, the molarity ratio of the mixed solution, the substrate, and the method of film preparation. When VBATDT is adsorbed on the metals, the 1,3,5-triazine-2,4-dithiol (heterocyclic) group acts as the adsorption site and changes the ring structure from the thione form to the thiol form. If VBATDT coexists with M10P near the substrate surface, the two kinds of monomers can build, at least, four kinds of chemisorbed layers on the metals. One is the monolayer of VBATDT adsorbed onto Au with two sulfurs in the heterocyclic group, in which the axis of symmetry of the ring is perpendicular to the surface. The second is the monolayer mainly consisting of VBATDT formed on the Ag or Cu substrate with the heterocyclic group tilted. The third is the thick film consisting of the polymer derived from VBATDT; this polymer can be generated on the Ag and Cu substrates from the concentrated mixture. The fourth is the thick film consisting of the polymer made mainly from M10P; this polymer can be prepared on the Cu substrate from the concentrated solution containing a high molarity ratio of M10P. The reasons for these various chemisorbed layers were discussed.

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.

Chemical-cure resin cement has been widely used for orthodontics. To improve the clinical handling of chemical-cure resin cement, a dual-cure resin cement system composed of methyl methacrylate (MMA), urethane dimethacrylate (UDMA) and light activator was developed. The purpose of this study was to estimate the efficacy of an experimental dual-cure resin cement. A composite bracket was bonded to the teeth with one of eight resin cements: (1) Unifast II (Uni II); (2) Unifast II containing camphor quinone (Uni II-CQ); (3) Transbond XT (TB); (4) Orthomite Superbond (SB); (5) Unifast LC (Uni-LC); (6–8) experimental dual-cure resin cement—Exp1, Exp2 and Exp3, respectively. Shear bond strength (SBS) of all of the bonded brackets was measured after the cementation. The data were statistically divided, the highest cement (Uni-LC), the next group (Exp1, Exp2, Exp3 and SB) and the lowest group (Uni II, Uni II-CQ and TB). The dual-cure resin cement exhibited a bonding efficacy comparable to that of Superbond.

To evaluate the effect of a dentin adhesive on sclerotic dentin, contraction gap width and shear bond strength were measured. Dentin cavity wall was pretreated with an experimental dentin bonding system with and without a dentin primer, or with a commercial dentin bonding system. In the experimental dentin bonding groups, contraction gap width of sclerotic dentin was significantly smaller than that of sound dentin when the cavity was not primed with glyceryl monomethacrylate. For each individual tooth, the correlation between contraction gap width and shear bond strength was insignificant. In conclusion, the bonding efficacy of dentin bonding systems to sclerotic dentin was superior to that of sound dentin. Further, it was determined that it was impossible to detect the interaction between the polymerization contraction stress of resin composites and the efficacy of dentin adhesives by measuring bond strength.

summary The purpose of this study was to examine the efficacy of experimentally developed high purity glyceryl mono-methacrylate (GM) as a dentine primer and to evaluate the possibility of allergic reaction. The efficacy of experimental dentine primers was evaluated by measuring the polymerization contraction gap width and the tensile bond strength. Allergic reaction was evaluated by the guinea-pig maximization test. The skin reaction was evaluated according to the criteria of the International Contact Dermatitis Research Group. Contraction gap formation was completely prevented and the tensile bond strength was not significantly affected by priming with GM on high-purity GM. The allergic response decreased when high-purity GM was employed as the challenger. It was concluded that the clinical use of the high-purity GM is beneficial as the delayed allergic reaction could be avoided with no detrimental effect on the dentine bonding.

The purpose of the present study was to evaluate the efficacy of an experimental self-etching dentin primer composed of TEGMA and phenyl-P using primary and young permanent teeth. The efficacy of the self-etching dentin primer was evaluated by measuring the wall-to-wall polymerization contraction gap width and the shear bond strength to the flat dentin surface.The contraction gap formation was prevented completely in the specimens primed with the 35 vol% TEGMA and 20% phenyl-P for 30 sec.

6-[N-(4-vinylbenzyl)propylamino]-1,3,5-triazine-2,4-dithione (VBATDT) and 10-methacryloyloxydecyl dihydrogen phosphate (M10P) are functional monomers used for the surface treatment of dental alloys. The aim of our study was to clarify the role of a commercial metal primer containing both the monomers in adhesion between resin and various dental metals on a molecular level. We used surface-enhanced Raman scattering (SERS) and infrared reflection absorption (IRA) spectroscopy. An SERS measurement was performed with a 647 nm laser line for a mixture of aqueous Au colloid and the primer. IRA spectra were taken for cast films of the primer on Au, Ag, Cu, and Cr surfaces as a function of rinse time, and for self-assembled monolayer (SAM) films from dilute mixed solution of VBATDT and M10P. These spectra indicate that VBATDT in the primer is mainly chemisorbed on Au, Ag, and Cu surfaces with respect to thickness, whereas only M10P is adsorbed on Cr. We also examined the tensile bond strengths between resin and Au, Ag, Cu, and Cr plates treated by VBATDT, with and without M10P, and found that VBATDT effectively promotes the bond strength between resin and the metals except for Cr, whereas M10P is effective only for Cr. These adhesion characteristics are consistent with the chemisorbed species on each metal surface as shown in the spectroscopic evidence.

The purpose of present study was to determine the possibility of nebulous discoloration of the oral mucosa of guinea pigs as a result of the application of dentine bonding agents. The materials used were the Clearfil® Photo Bond (CPB) system's mixture agent, universal agent and catalyst agent. Four types of experimental catalysts were used. In male albino guinea pigs weighing 300–500 g, oral mucosa irritation tests were performed in accordance with the guidelines of the Cosmetic, Toiletry and Fragrance Association (CTFA). Macroscopical findings on the oral mucosa showed that there was strong nebulous discoloration immediately after application of CPB mix and CPB catalyst and throughout the experimental periods. However, CPB without 10-methacryloxdecyl dihydrogen phosphate (MDP) did not produce noticeable nebulous discoloration and inflammation. The CPB mix caused pathological changes, such as paraketosis and hyperkeratosis on the endepidermis of the mucosa, immediately after its application.

The effect of the cavosurface angle of dentin cavities prepared in extracted human molars on the cavity adaptation of a resin composite was evaluated by measuring the gap width between the resin composite and the dentin cavity wall. Cavities with cavosurface angles of 90 degrees, 120 degrees, 135 degrees, or 150 degrees were pretreated with one of two commercial dentin bonding systems or an experimental dentin bonding system. The contraction gap width was measured at both the cavity margin and the section cavity using a light microscope. Complete cavity adaptation was obtained with pretreatment of the experimental groups regardless of the cavosurface angle. The contraction gap observed at the cavity margin was prevented with the two commercial dentin bonding systems when the cavosurface angle was increased to 150 degrees. A high correlation was observed between the contraction gap width and the proportion of the free surface to the adhesive surface of the resin composite restoration.

It was widely known that 2-hydroxyethyl methacrylate (2-HEMA) can cause contact dermatitis. Commercially available dentine primers and dentine bonding agents that contain 2-HEMA are widely used. The purpose of this study was to investigate the cumulative irritation and delayed hypersensitivity caused by commercial dentine bonding systems when applied to the skin of guinea pigs. We have concluded that almost no dentine bonding systems cause cumulative irritation, but some commercially available dentine bonding systems may produce delayed hypersensitivity.

The dentin cavity adaptation and setting characteristics of four commercial compomers were evaluated by measuring the wall-to-wall contraction gap width in the cylindrical dentin cavity and measuring the compressive strength for a maximum of 14 days after setting. The dentin cavity wall was pretreated by the dentin adhesives according to each manufacturer's instructions or the experimental contraction gap-free dentin bonding system. Complete marginal integrity was obtained in only one compomer and two resin composites which were combined with the experimental dentin bonding system. The compressive strength of two resin composites and two compomers ten minutes after setting was comparable to that after 14 days which indicated that the compomers exhibited setting characteristics as rapidly as the resin composite. It was concluded that a high efficacy dentin bonding system is required for commercial compomers to prevent gap formation during irradiation caused by the rapid setting shrinkage.

The efficacy of four commercial and two experimental dentin bonding systems was examined by observing the cavity adaptation of commercial light-cured resin composites restored in the dogs scheduled to be sacrificed after a medical experiment. Before being sacrificed, a cylindrical class V cavity was prepared in each canine, and the cavity wall was treated with one of four commercial dentin bonding systems according to the manufacturers instructions followed by resin composite filling. The maximum contraction gap widths at the occlusal, gingival and axial cavity wall were measured on the cavity section 30 min after the polymerization of the resin composite under a light microscope. Contraction gap formation was completely prevented in only one of the experimental groups in which the cavity wall was primed with 35 vol% glyceryl mono-methacrylate (GM). In addition, observation of cavity adaptation in the canine in vivo was useful to estimate consistently the efficacy of the bonding systems.

The effects of 2-hydroxyethyl methacrylate (2-HEMA) both in the primer and in the commercial dentin bonding agent on the efficacy of the dentin bonding system was evaluated by measuring the polymerization contraction gap width of a commercial resin composite restored in a cylindrical dentin cavity prepared in an extracted human molar. Contraction gap formation was prevented in the group of the EDTA-conditioning followed by glyceryl mono-methacrylate, ethylene glycol and 1, 6-hexanediol priming regardless of the 2-HEMA content in the dentin bonding agent containing 10-methacryloxydecyl dihydrogen phosphate. However, gap formation could not be prevented completely by the 2-HEMA priming. Therefore, it was possible to conclude that 2-HEMA was neither essential in the primer nor in the dentin bonding agent because of its low bonding efficacy and the resulting side effects on skin tissue as a delayed allergic reaction.

10-Methacryloyloxydecyl dihydrogen phosphate (M10P) for use in dentistry has recently been noted as an adhesive monomer contained in a metal primer. Although the treatment of a metal surface with primer before the application of resin is recognized to improve the adhesion between metal and resin, the role of M10P in the adhesion process has not been clarified. In this study, infrared reflection absorption (IRA) spectroscopy was employed to study the adsorption structures of M10P as well as 2-methacryloyloxyethyl dihydrogen phosphate (M2P) on evaporated silver substrates. The IRA spectra of the self-assembled films of those phosphates verified the adsorption of M10P or M2P on silver substrates from the methyl methacrylate solutions (5 × 10−5 mol/L). The saturation coverages of M10P and M2P were completed after about 50 and 25 min, respectively. Two characteristic bands around 980 and 1080 cm−1 due to the PO32− stretching vibrations were observed. These results indicate that the phosphate groups of both monomers are adsorbed to silver surfaces in the dissociated form, −PO32−, and form hydrophobic monolayers. The monolayer of M10P was found to be more durable against thermocycling in water than that of M2P by IRA measurements. The roles of M10P in the metal primer are presumably to form such a monolayer with appreciable durability and to promote polymerization with resin monomers. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 37, 252–260, 1997.

Class V cavities were prepared and restored with resin composite containing antibacterial filler powder (Apacider-AW, Ap-AW) using experimental restorations. The restored teeth were incubated in vitro with the cariogenic bacteria Streptococcus mutans IFO 13955. Ground sections were then prepared and examined using macrophotography. Lesions of the outer and inner wall were noted, and the depths of which the lesions penetrated were measured. We found that, in restorations containing 1-5 wt% Ap-AW, caries penetrated the marginal area, while in restorations containing 10 wt% Ap-AW the margin remained free of caries out to a distance of about 1.1 and 1.8 mm on the occlusal and gingival sides, respectively.

Objectives: The purpose of this study was to examine the bonding effect of polyvalent alcohols as dentine primers without a methacrylate group, which may cause contact dermatitis. Methods: The efficacy of polyvalent alcohols as dentine primers was estimated by measuring the wall-to-wall polymerization contraction gap width of a light-activated resin composite filled in a cylindrical dentine cavity in an extracted human tooth. A dentine cavity was cleaned with ethylenediaminetetraacetic acid (EDTA) and primed with an aqueous solution of either ethylene glycol, glycerol, erythritol, xylitol or sorbitol at concentrations of between 25 and 75 wt%. A light-cured resin composite was filled after the application of a commercial dual-cured bonding agent. Results: Contraction gap formation was completely prevented only in the group in which the dentine cavity had been primed with an aqueous solution of 62.5 wt% ethylene glycol. Furthermore, in the measurement of a tensile bond strength to a flat dentine surface, high tensile bond strength (17.5 ± 4.4 MPa) was observed in the group that was primed with 62.5% ethylene glycol solution. Conclusion: These results suggest that it is not necessary to dissolve methacrylates in a dentine primer when the primer is dried with a blast of compressed air before application of a polymerizable, suitable bonding agent. It is concluded that a dentine primer composed of polyvalent alcohol solutions without a methacrylate group which may cause contact dermatitis, is effective as a dentine primer, affects the dentine surface, and promotes the efficacy of the dentine bonding system.

Background The resistance of bleached enamel to demineralization has not been elucidated fully. In this study, the authors aimed to examine the level of in vitro demineralization of human tooth enamel after bleaching by using two common bleaching regimens: home bleaching (HB) and office bleaching (OB) with photoirradiation. Methods The authors bleached teeth to equivalent levels by means of the two bleaching regimens. They used fluorescence spectroscopy to measure the reduction in enamel density and the release of calcium into solution after storing the treated teeth in a demineralizing solution for two weeks. They also visualized and quantified mineral distribution in demineralized bleached enamel over time by using a desktop microcomputed-tomographic analyzer. Results Enamel subjected to HB or to photoirradiation without bleaching showed increased demineralization. In contrast, enamel treated with OB was more resistant to demineralization. This resistance to demineralization in teeth treated with OB presumably is due to peroxide's permeating to deeper layers of enamel before being activated by photoirradiation, which enhances mineralization. Conclusions The mineral distribution pattern of enamel after treatment plays a critical role in providing resistance to demineralization in whitened teeth. Practical Implications OB confers to enamel significant resistance to in vitro demineralization. Dentists should supervise the nightguard HB process.

Objective: The purpose of this study was to investigate the adhesion of glass ionomer cements to dentin and the effect of pretreatment using Carisolv. Study design: Forty extracted permanent teeth with caries were used for this study. All lesions were removed using the Carisolv system and teeth were divided into eight groups. Groups 1 to 4 were filled with three types of conventional glass ionomer cements and a resin modified glass ionomer cement. Group 8 was restored with composite resin. In the remaining three groups (Groups 5 to 7), several pretreatment procedures, including EDTA and dentin primer application and a combination of these, were performed before restoring with resin modified glass ionomer cement. All restorations were thermocycled, and microleakage tests were performed on all teeth. Results: There were no statistical differences among Groups 1, 2 and 3 or between Groups 4 and 8. However, Groups 1 to 3 had higher microleakage levels than Groups 4 and 8. Groups 5 to 7 showed similar leakage levels as Group 4. Conclusion: Pretreatment with EDTA or dentin primer did not improve bonding ability. Combination of caries removal using Carisolv and a resin modified glass ionomer cement restoration without pretreatment seems to be an acceptable method for caries treatment.

The purposes of this study were to examine whether 2-HEMA, GM, and methacrylic acid cause contact dermatitis, and to determine the optimum concentrations of these primers for sensitization and challenge in guinea pigs. A sensitizing concentration of 0.2% 2-HEMA resulted in strong rubefaction and several vesiculopapules in response to the challenge, and a sensitizing concentration of 0.5% GM produced strong rubefaction at 24 hours. We also observed the development of contact dermatitis on human brachia in a closed-patch test. Skin that was treated with both 2-HEMA and GM clearly showed the onset of rubefaction and itchiness. 2-HEMA caused sensitized delayed allergic reactions at all the concentrations tested.

Objective: The adaptation of experimental dentine bonding systems has been evaluated in vivo. Methods: A cylindrical cavity which extended into dentine was prepared in the facial surface of vital teeth that were to be extracted for orthodontic reasons. The preparations were restored with a commercial light-activated resin composite that was mediated by experimental dentine bonding systems. The restored teeth were extracted as soon as possible following polymerization of the composite. The marginal and internal adaptation of the resin composite restoration was observed under a light microscope in both horizontal and longitudinal sections of the teeth immediately after extraction. Results: Of the experimental dentine bonding systems investigated, those including a primer of glyceryl methacrylate showed complete adaptation whereas those with primers of 2-HEMA showed a contraction gap in three out of 10 specimens.

The purpose of the present study was to evaluate the safety of ethylene glycol (EG) and 1, 6-hexanediol (HD) solutions as experimental dentin primers when subjected to the guinea pig maximization test (GPMT), primary irritation test, cumulative skin irritation test and human patch test. No primary and cumulative skin irritation resulting from the use of 62.5% EG or 45% HD solutions was observed. In the case of GPMT, the animals sensitized with 2-hydroxyethyl methacrylate (2-HEMA) responded to 100% HD. 62.5% EG and 45% HD as dentin primers were safer than 2-HEMA such as a methacrylic primer.

Objectives: The effects of the duration of cleaning and priming on the marginal adaptation of a light-activated resin composite in a cylindrical dentine cavity were examined by measuring the width of the wall-to-wall polymerization contraction gap. Methods: The dentine cavity was cleaned with ethylene diamine tetra-acetic acid (EDTA) and primed 35 vol% hydroxyethyl methacrylate (HEMA) or glyceryl methacrylate (GM) solution for up to 60 s. The cavity was filled with a light-cured resin composite after the application of a dual-cured dentine bonding agent. Results: The formation of a contraction gap by the composite appeared to be prevented completely, regardless of the duration of priming with GM solution, when the cavity was cleaned with EDTA for 60 s. When cleaning was limited to just 30 s, GM priming had to be prolonged to 60 s to obtain complete marginal integrity. A significantly wide contraction gap was observed without EDTA cleaning, even when the cavity wall was primed with GM solution for 60 s. Conclusion: GM solution was a better dentine primer than HEMA solution, since HEMA priming did not prevent gap formation under any of the conditions tested.

Objective: This study was undertaken to examine the possibility of a delayed hypersensitivity reaction or contact dermatitis occurring in the guinea-pig in response to methacrylate derivatives used as experimental dentine primers. Method: The dentine primers 2-HEMA, GM, MA and MMA were tested in a guinea-pig maximization test. Results: All the dentine primers tested produced positive delayed hypersensitivity reactions in the guinea-pig. MMA produced the most severe reaction. Conclusion: It is concluded that in the clinical situation, clinicians and other members of the dental team should be aware of the need for careful handling of the dentine primers tested.

The efficacy of a high-pulse Er:YAG laser in treating caries was evaluated clinically. Caries removal and cavity preparation were performed using an Er:YAG laser (Er-D1, Hoya Continuum, Japan) at 30–350 mJ/pulse, 20 or 30 pps without local anesthesia. The cavities were restored with adhesive resin composite according to the manufacturer's instructions. After treatment, the patients were asked to express the level of pain and discomfort felt during cavity preparation with the Er:YAG laser by means of a Visual Analogue Scale (VAS). The mean VAS value for discomfort was 6.03 and female patients recorded a lower value than male patients (P

A wave length of Er:YAG laser is 2940 nm; it has high absorbability in water, and is notable as dental hard tissue cutter. Previous study at 10-Hz irradiation showed good result in vivo. The aim of this study is to evaluate the effect of the higher pulse rate, 30 Hz, Er:YAG laser for adhesive resin cavity preparation in vivo. Sixty cavities were prepared by high-pulse Er:YAG laser, and clinical symptoms were recorded by operator and donor, respectively. The results showed that high-pulse rate Er:YAG offers less painful, safe and effective cavity preparation without any side effect.

The dentin bonding efficacies of two commercial dentin bonding systems and experimental self-etching dentin primers composed of methacryloxyethyl hydrogen phenyl phosphate (Phenyl-P) and either hydroxyethyl methacrylate (HEMA) or glyceryl methacrylate (GM, 2,3-dihydroxypropyl methacrylate) were examined. The wall-to-wall polymerization contraction gap width of a commercial light-activated resin composite in a cylindrical dentin cavity and the tensile bond strength to a flat dentin surface were measured. Changes in dentin hardness were determined by Micro Vickers Hardness measurement, and an SEM observation was performed after priming. Formation of a contraction gap was completely prevented by the application of Phenyl-P diluted in HEMA or GM solution combined with a commercial dentin bonding agent, although gap formation was evident in nearly half of the specimens with both commercial dentin bonding systems. The mean tensile bond strengths of the tested groups varied from 16.3 to 20.7 MPa, and there were no significant differences between groups. Based on the measurement of Micro Vickers Hardness and SEM observation after priming, a slight reduction in dentin hardness was observed. However, this reduction in dentin hardness due to self-etching priming did not significantly correlate with either contraction gap width or tensile bond strength.

The presence of macrophages in dental pulp is well known. However, whether these macrophages proliferate and differentiate in the dental pulp in situ, or whether they constantly migrate from the blood stream into the dental pulp remains unknown. We have examined and compared the development of dental pulp macrophages in an organ culture system with in vivo tooth organs to clarify the developmental mechanism of these macrophages. The first mandibular molar tooth organs from ICR mice aged between 16 days of gestation (E16) to 5 days postnatally were used for in vivo experiments. Those from E16 were cultured for up to 14 days with or without 10% fetal bovine serum. Dental pulp tissues were analyzed with immunohistochemistry to detect the macrophages and with reverse transcription and the polymerase chain reaction (RT-PCR) for the detection of factors related to macrophage development. The growth curves for the in vivo and in vitro cultured cells revealed similar numbers of F4/80-positive macrophages in the dental pulp. RT-PCR analysis indicated the constant expression of myeloid colony-stimulating factor (M-CSF) in both in-vivo- and in-vitro-cultured dental pulp tissues. Anti-M-CSF antibodies significantly inhibited the increase in the number of macrophages in the dental pulp. These results suggest that (1) most of the dental pulp macrophages proliferate and differentiate in the dental pulp without a supply of precursor cells from the blood stream, (2) M-CSF might be a candidate molecule for dental pulp macrophage development, and (3) serum factors might not directly affect the development of macrophages.

The aim of this study was to investigate the diffusion of red-stained experimental GM primer and blue-stained dentin bonding agent into EDTA-conditioned dentin and the effect of GM priming on contraction gap formation. After GM priming at 0, 35, 70, or 100 vol%, marginal adaptation was evaluated by measuring the wall-to-wall contraction gap width of a light-activated resin composite (Palfique Estelite, Tokuyama Dental, Japan) mediated with a commercial dentin bonding agent (Clearfil Photo Bond, Kuraray Medical, Japan). Contraction gap formation was completely prevented when treated with 35 vol% GM primer. Moreover, after treatment with 35 vol% GM, the red and blue dyes of stained GM primer and dentin bonding agent diffused up to a depth of 40 µm into the dentin surface. The diffusion of primer and bonding agent into EDTA-conditioned dentin was essential for bonding efficacy although SEM observation revealed an absence of hybrid layer formation.

Previously, we reported that the integrity of a resin composite restoration deteriorated when the dentin cavity wall was decalcified by conditioning. In this study, to evaluate the bonding between dentin adhesive and non-decalcified dentin surface, we experimented with a novel method of using a high-pressure water spray device to prepare smear layer-free dentin surfaces. When the smear layer was removed, shear bond strength significantly increased regardless of the removal method employed. Further, with glyceryl monomethacrylate (GM) priming, no significant differences in bond strength were observed among these smear layer removal methods: ethylenediamine tetraacetic acid (EDTA) conditioning, phosphoric acid conditioning, and removal by water spray. It was also found that GM priming was key to achieving marginal integrity, whereas contraction gap width increased with phosphoric acid conditioning. It was thus concluded that the efficacy of a dentin adhesive should be evaluated by consistently observing the contraction gap in three-dimensional cavities rather than by mere measurement of bond strength to a flat dentin surface.

Induction and suppression of wind-up were studied in 97 tooth pulp-driven neurons in the trigeminal subnucleus caudalis, using Wistar albino rats anesthetized with urethane and alpha-chloralose. Tooth pulp stimulation applied to an ipsilateral lower incisor evoked early discharges, indicating excitatory inputs from A-delta fibers and subsequent late discharges from C-fiber volleys in caudal neurons. Wind-up was efficiently evoked by stimulation delivered at 0.3-1 Hz, with current intensity sufficient to evoke late discharges. Conditioning stimulation of the arcuate nucleus of the hypothalamus (ARH) suppressed late discharges, including wind-up, without affecting the A-fiber response. Focal cooling of the periaqueductal gray (PAG) abolished the suppression by the ARH and further enhanced the wind-up of the caudal neurons. These results suggest: 1) Temporal summation of depolarization evoked by C-fiber volleys builds wind-up in caudal neurons; 2) ARH stimulation suppresses late discharges by blocking synaptic transmission from C-fiber inputs, and this interrupts prolonged facilitation of the neurons; 3) the ARH is involved in induction of inhibitory controls descending from the PAG to the trigeminal caudalis.

We studied the allergic reaction of guinea pigs to glyceryl methacrylate (GM), hydroxyethyl methacrylate (HEMA) and meso-erythritol methacrylate (EM), which are used as dentin primers. On the 18th day of the application test, when macroscopic investigation revealed an inflammatory reaction, the methacrylic acid-treated group showed marked eschar formation in comparison with the control group. In each of the dentin primer groups, a slight degree of skin redness was noted, but there were no serious symptoms. On the 25th day, the applications were resumed macroscopic inspection on the 32nd day found eschar in the methacrylic acid group only. Therefore, this experiment with dentin primers suggests a delayed allergic reaction. Local irritability test showed a more severe reaction than the application test. In this test, all experimental dentin primers and methacrylic solution promptly showed inflammation, and the chemical compound, methacrylic acid was a factor in inflammation.

A study of the adhesive interface between 4-MET/MMA-TBB resin and hydroxyapatite or bovine enamel was reported. The present report is a continuation of that study. The possible chemical interaction between 4-methacryloxyethyl trimellitic acid (4-MET) and bovine or human dentin was examined by laser Raman spectroscopy. A 4-MET monomer solution was prepared by evaporating two thirds of the methyl methacrylate (MMA) in a commercial dentin adhesive. The solution was then applied to a dentin surface after treating the surface with an aqueous solution of 10% citric acid containing 3% ferric chloride. A salt formed on both bovine and human dentin surfaces. This salt was formed by the process we previously reported in which 4-MET formed a salt on the hydroxyapatite and bovine enamel. No evidence was observed of chemical reaction between 4-MET and any organic component in the dentin.

To evaluate the efficacy of a conventional and newly-developed caries detector (Caries Check) by measuring the Vickers microhardness (VMH) and DIAGNOdent value of the dentin cavity wall of extracted human teeth after removing carious dentin that was stained by the caries detector.30 human teeth with coronal dentin caries extending halfway through the dentin were sectioned and extracted for use in this study. As a control, the longitudinal section of a caries-free extracted human tooth was prepared. The VMH and DIAGNOdent values were measured and the microstructure of the dentin cavity wall was examined using a scanning electron microscope (SEM).When Caries Check was employed as a guide for carious dentin removal, the microhardness of the cavity wall was significantly lower than the normal dentin and the DIAGNOdent value indicated that the dentin may have recalcified. SEM observations of the stained regions revealed that Caries Check did not stain the sclerotic dentin. Based on these findings, Caries Check may be a useful modality because the excavation of the dentin structure was shallower and the sclerotic dentin was preserved.

The aim of this study was to evaluate tri-ethylene glycol mono-methacrylate (TEGMA) in terms of dermatological allergic reaction using a Guinea Pig Maximization Test. Skin reaction was evaluated according to the criteria of International Contact Dermatitis Research Group. TEGMA, as a constituent in new primers, has been reported to contribute to a priming ability similar to that of highly purified glyceryl mono-methacrylate (GM). In this study, it was found that its adverse effect was less than that of 2-hydroxy ethyl methacrylate (2-HEMA), but similar to that of highly purified GM. In conclusion, it was anticipated that TEGMA would hereafter replace 2-HEMA as a primer, as it posed a lower risk of triggering dermatological allergic reaction.

summary The bonding efficacy of four one-bottle adhesives (OptiBond Solo Plus, Gluma Comfort Bond, One Step and Prime & Bond NT) and a multi-step adhesive (Clearfil Photo Bond) as a control was evaluated. The dentine cavity wall was conditioned with phosphoric acid or ethylenediaminetetraacetic acid (EDTA) and the marginal integrity was estimated by measuring the wall-to-wall contraction gap width between the composite and the dentine cavity surface. In the positive control group, the adhesive was applied following glyceryl methacrylate (GM) priming. The analyses were performed by Kruskal–Wallis and Mann–Whitney U-tests. One-bottle adhesives were clearly inferior to the multi-step bonding system in marginal integrity when dentine was conditioned with EDTA. The present findings also suggested that the marginal sealing ability of ethanol-based one-bottle systems was better than acetone-based one-bottle systems when dentine surfaces were conditioned with EDTA. Nevertheless, further investigations are needed on the function of fillers in one-bottle adhesives for the prevention of contraction gaps.

To test the efficacy of the multiple application of a total-etch dentin adhesive was investigated by measuring (1) the contraction gap width of a light-activated resin-based composite in a cylindrical dentin cavity and (2) the early tensile bond strength to a flat dentin surface with the Single Bond Dental Adhesive System.Contraction gap width was measured in a cylindrical dentin cavity (3 mm x 1.5 mm) treated with a single coat or double coats of the Single Bond adhesive and restored with Silux Plus or Z-100. As control, the cavity was treated with an experimental dentin bonding system consisting of EDTA, 35% GM and Clearfil Photo Bond. Early tensile bond strengths of Silux Plus or Z-100 were measured on the flat dentin surface treated with the three bonding procedures as in the contraction gap study within 10 min. after final cure.The contraction gap of Silux Plus and Z-100 was prevented with the double coats of the Single Bond adhesive, whereas the contraction gap of Z-100 was not prevented with the single coat of the Single Bond and the experimental system. When the film thickness of the Single Bond system was less than 2 microm, the gap could not be prevented. The tensile bond strengths of Silux Plus and Z-100 to flat dentin mediated with the three bonding procedures were not significantly different (P0.05).

Objective. To evaluate the effect of a dentine bonding system to sclerotic dentine in comparison with normal dentine. Methods. The efficacy of the dentine bonding system to sclerotic dentine was examined by measuring wall-to-wall polymerization contraction gap width. The dentine cavity wall was pretreated with an experimental dentine bonding system with and without a dentine primer. The dentine primer was glyceryl mono-methacrylate (Blemmer GLM, NOF Corp., Tokyo, Japan) (GM), which contained esterified methacrylate with a polyvalent alcohol, which is similar to 2-HEMA. The structure of sclerotic dentine and the changes to that structure caused by etching were observed using a scanning electron microscope (SEM). Results. With GM priming, complete marginal integrity was obtained regardless of the type of dentine. Without GM priming, complete marginal integrity was obtained in half of the specimens of the sclerotic dentine, and was not obtained in any of the specimens of normal dentine. In the SEM study, the structure of sclerotic dentine was considered to be viable for adhesion. However, this was not the case when etched with phosphoric acid. Conclusion. It was concluded that sclerotic dentine had a clear advantage over normal dentine with regard to the adaptation of resin composites. Therefore the structure of sclerotic dentine possesses a naturally derived structure to which a primer may attach. Sclerotic dentine is part of the body's natural defenses and should be preserved. It should not be exposed to acid etching which would damage its structure.

The bonding efficacy of sclerotic dentin was determined by measuring the polymerization contraction gap width of a commercial light-activated resin composite in a cervical defect and by measuring the micro-Vicker's hardness at the dentin adhesive surface; morphological characteristics were observed using a scanning electron microscope in extracted human incisors and premolars. Contraction gap formation was completely prevented when the cavity wall was primed with 35 vol% glyceryl mono-methacrylate solution after 0.5 mol/L EDTA conditioning. The contraction gap width was significantly decreased when the resin composite was filled into the sclerotic dentin cavity even when priming was omitted. These results suggest that the sclerotic dentin, which is frequently observed in cervical defects, should be preserved as a substrate because it exhibits an effect of dentin priming and is suitable for bonding.

The xenoestrogenic substance bisphenol-A is widely used as a synthetic precursor of resin monomers, such as bisphenol-A diglycidyl methacrylate. Reports describing the release of bisphenol-A from polymerized resin into saliva have aroused considerable concern regarding exposure to xenoestrogen by dental treatment. The purpose of the present study was to demonstrate a reliable methodology of detecting the trace amounts of bisphenol-A in dental materials. Bisphenol-A was separable from bisphenol-A diglycidyl methacrylate, which is often employed as the principal dimethacrylate monomer, by selective extraction with a Sep-Pak C18 cartridge. Using this extraction method in combination with a gas-chromatography mass-spectrometry, we have obtained evidence that all unpolymerized materials used in this study were contaminated with bisphenol-A. Quantitative analysis using a deuterium-labeled compound as an internal standard revealed bisphenol-A contents in commercial dental materials ranging from < 1 microgram/g material to about 20 micrograms/g material. The polymerized dental materials released up to 91.4 ng bisphenol-A/g material into phosphate buffered saline during 24-h incubation. These results indicate that bisphenol-A can be released from dental materials, however the leachable amount would be less than 1/1000 of the reported dose (2 micrograms/kg body weight/day) required for xenoestrogenisity in vivo.

The objective of the present study was to understand the role of the functional monomers in dentin bonding agents of an experimental dentin bonding system by measuring the wall-to-wall contraction gap and tensile bond strength measurement. The efficacy of three commercial dentin bonding agents after using EDTA for conditioning and GM for priming was evaluated by measuring the contraction gap of the resin composite in a cylindrical dentin cavity, and by measuring the tensile bond strength of the composite to a flat dentin surface. The effect of the functional monomers was demonstrated by the contraction gap measurement alone. The value of the contraction gap was significantly different between the commercial dentin bonding agents and these agents without functional monomers (p

In order to clarify the role of a primer on the adhesion between dental precious metals and resin, surface-enhanced Raman scattering (SERS) technique has been applied to the structural analysis of the adhesive monomer, 6-(N-(4-vinylbenzyl)propylamino)-1,3,5-triazine-2, 4-dithione (VBATDT) adsorbed on colloidal Au surfaces. VBATDT is one of the major components of commercial primers. A mixture of a methanol solution of VBATDT and aqueous Au colloid was illuminated by the 647.1 nm line from a Kr ion laser to obtain the SERS. The most intense peak at 458 cm-1 due to C = S stretching in the Raman spectrum of solid VBATDT disappears completely in the SERS, while all the other peaks due to vinylbenzyl group vibrations remain unchanged. It suggests that some structural change occurs in VBATDT upon adsorption on Au which involves the C = S bonds and that the molecule undergoes thione-thiol-type tautomerization in the adsorption process. The SERS spectrum of a commercial primer containing VBATDT exhibits a similar spectral pattern. The present results lead us to conclude that some specific interactions exist between the sulfur atoms of VBATDT and Au surface to form chemical bond likes, which are effective to improve the bond strength between dental precious metals and resin. The ambivalent properties of the primer, chemical stability in storage and chemical affinity to Au, are also explained by the thione-thiol-type tautomerization of VBATDT on the basis of the spectroscopic evidence.

The effectiveness of newly developed commercial dentin bonding systems (SB, MB II and KB) was evaluated by measuring the contraction gap width of a resin composite restored into a cylindrical dentin cavity prepared in an extracted human molar and by measuring the tensile bond strength to the flat dentin surface. In addition, calcium loss during dentin conditioning was analyzed using electron microanalyses. An experimental dentin bonding system composed of EDTA conditioning, GM solution priming and a bonding agent containing 10-MDP was employed as a control in which it was presumed that contraction gap formation was prevented completely. However, gap formation was observed using the three commercial simplified dentin bonding systems. SEM observation showed that the gap was formed between the resin composite and the top surface of the dentin cavity wall indicating that the fracture occurred at the adhesive interface, but never inside the dentin nor inside the resin composite.

Objectives: To evaluate the effect of two experimental primers based on glyceryl methacrylate (GM, 2,3-dihydroxypropyl methacrylate) and 2-hydroxyethyl methacrylate (2-HEMA) on the marginal adaptation of light-cured composite placed into cylindrical dentine cavities and to study the interfacial microstructure. Methods: The bonding efficacy of two experimental dentine primers combined with a dentine cleanser composed of either 0.5 mol l −1 EDTA neutralized to pH 7.4 by sodium hydroxide or 10% citric acid containing 3% ferric chloride (10-3 solution), and a commercial dentine bonding agent containing phosphate ester, were examined by measuring the wall-to-wall polymerization contraction gap of a commercial light-activated resin composite placed into cylindrical dentine cavities. The adhesive interface between the dentine and the dentine adhesive was observed using a transmission electron microscope (TEM). Results: The formation of a contraction gap was completely prevented by priming with GM, regardless of the dentine cleanser used. However, in groups primed with 2-HEMA, gap formation was observed in three and four specimens out of 10 in the groups that were cleaned with the EDTA and 10-3 solution, respectively. In samples primed with GM, a high-density layer was observed by TEM at the superficial dentine in the hybrid layer, which may have indicated a high monomer content, whereas no density variations were observed in the hybrid layer in samples primed with 2-HEMA.