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This study was conducted to determine the effect of a 3.5% hydrogen peroxide solution containing titanium dioxide on bonding of resin to pulp chamber dentin. Extracted bovine anterior teeth were allocated to three groups of ten teeth each. The coronal labial pulp chamber dentin was exposed and bleached with 3.5% hydrogen peroxide with titanium dioxide with 405-nm diode laser irradiation for 15 min (Group 1); 30% hydrogen peroxide with halogen lamp irradiation for 15 min (Group 2); and distilled water for 15 min (Group 3). After bleaching, the pulp chamber dentin was prepared for composite resin bonding and the interface between the resin and dentin was observed by scanning electron microscopy. The microtensile bond strength (μTBS) and failure patterns were determined. The μTBS values (mean ± SD) were: 17.28 ± 5.79 MPa (n = 36), 0 MPa, and 26.50 ± 9.83 MPa (n = 36) in Groups 1, 2, and 3, respectively. The μTBS in Group 3 was significantly higher than that in Group 1 (P < 0.05). Hybrid layers and resin tags were clearly observed at the interface in Groups 1 and 3, but not in Group 2. Adhesive failure was mainly observed in Group 1, whereas dentin failure was the main failure pattern in Group 3.

Toyotarou Sugawara1, Atsushi Kameyama2, Akiko Haruyama3, Takumi Oishi4, Nobuyuki Kukidome2, Yasuaki Takase2, Masatake Tsunoda21Undergraduate Student, Tokyo Dental College, Chiba, Japan; 2Division of General Dentistry, Tokyo Dental College Chiba Hospital, Chiba, Japan; 3Department of Dental Materials Science, Tokyo Dental College, Chiba, Japan; 4Department of Dentistry and Oral Surgery, Keio University School of Medicine, Tokyo, JapanObjective: To investigate the influence of maintenance spray on resin bonding to dentin.Materials and methods: The crown of extracted, caries-free human molars was transversally sectioned with a model trimmer to prepare the dentin surfaces from mid-coronal sound dentin, and then uniformly abraded with #600 silicon carbide paper. The dentin surfaces were randomly divided into three groups: oil-free spray group where maintenance cleaner for air bearing handpieces was sprayed onto the dentin surface for 1 s and rinsed with water spray for 30 s; oil-containing spray group where maintenance cleaner for micro motor handpieces was sprayed onto the dentin surface for 1 s and rinsed with water spray for 30 s; and control group where the surface was rinsed with water spray for 30 s and then air-dried. These surfaces were then bonded with Clearfil SE Bond (Kuraray Medical), and resin composite (Clearfil AP-X, Kuraray Medical) build-up crowns were incrementally constructed on the bonded surfaces. After storage for 24 h in 37°C water, the bonded teeth were sectioned into hour-glass shaped slices (0.7-mm thick) perpendicular to the bonded surfaces. The specimens were then subjected to microtensile bond strength (μTBS) testing at a crosshead speed of 1.0 mm/min. Data were analyzed with one-way ANOVA and the Tukey-Kramer test.Results: Maintenance spray-contaminated specimens (oil-free and oil-containing spray groups) showed significantly lower μTBS than control specimens (P < 0.05). However, there was no significant difference between the spray-contaminated groups (P > 0.05).Conclusion: Maintenance spray significantly reduces the bond strength of Clearfil SE Bond to dentin.Keywords: microtensile bond strength, lubricant, maintenance spray, contamination, dentin bonding

The purpose of this study was to evaluate the influence of Er:YAG laser irradiation on the bond strength to dentine of three single-step adhesives (AQ Bond Plus, G-Bond, and Clearfil Tri-S Bond), and one two-step self-etch adhesive (Clearfil Megabond) as a control.The vast majority of the numerous reports on resin bonding to Er:YAG-lased dentine have concluded that Er:YAG laser irradiation is less effective in terms of bond strength, because of the sub-surface damage it produces. However, its effect in combination with single-step adhesives on bonding to dentine remains to be clarified.Eighty bovine incisors were ground with silicon carbide paper to obtain a flat dentine surface, which 40 were irradiated with an Er:YAG laser. Both lased and unlased dentine was bonded to a resin composite with each adhesive. Tensile bond strength was determined after 24 h of storage in water at 37 degrees C. Failure patterns after tensile bond testing was analyzed by scanning electron microscopy.The two-step self-etch adhesive (Clearfil Megabond) showed the highest bond strength to unlased dentine, but was significantly less effective on lased dentine than the three single-step adhesives. On the other hand, AQ Bond Plus produced an effective bond strength to both lased and unlased dentine, perhaps due to its low viscosity.The single-step adhesives tested in this study were as effective in combination with Er:YAG-lased dentine as the two-step self-etch adhesive.

Novel Synthesis of Polymers with Well-Defined Structures Based on Selective Reaction of Cyclic Sulfides and Cyclic Ethers Catalyzed by Quaternary Onium Salts

This study determined the bond strengths to Er:YAG laser-irradiated and non-irradiated bovine enamel of three one-step self-etch adhesives (AQ Bond Plus (AQP), G-Bond (GB), and Clearfil Tri-S Bond (TS)) and one two-step self-etch adhesive (Clearfil Megabond (MB)). Eighty SiC paper-ground bovine enamel surfaces were used, of which half were laser-irradiated. The enamel surfaces were bonded to a resin composite with each adhesive, and tensile bond strengths were determined after 24 hours. For non-irradiated enamel groups, MB achieved greater bond strength to enamel than GB and TS (p0.05), but no significant difference was found between MB and AQP (p0.05). For laser-irradiated enamel groups, no significant differences were found among the four adhesives (p0.05). Additionally, for each adhesive, no significant differences were found between laser-irradiated and non-irradiated enamel. It was thus concluded that Er: YAG laser irradiation of enamel did not affect the tensile bond strength of one-step and two-step self-etch adhesives.

The purpose of this study was to evaluate the hardness of the adhesive interface between resin and Er:YAG laser-irradiated bovine dentin by nano-indentation.It has been reported that laser output energy and pulse repetition rate affect the tensile bond strength in Er:YAG laser-irradiated dentin.Three laser settings were evaluated at the same total energy level (approximately 1.0 W): 100 mJ/pulse-10 pps (100-10), 50 mJ/pulse-20 pps (50-20), and 33 mJ/pulse-30 pps (33-30). Laser-irradiated dentin in each group was conditioned with 10% citric acid solution containing 3% ferric chloride for 15 sec, rinsed with distilled water for 30 sec, and bonded to PMMA rods with 4-META/MMA-TBB resin. The bonded specimens were sectioned vertically, embedded in epoxy resin, and their nano-hardness measured. A non-irradiated control group was also investigated.The adhesive resin interface in the controls showed the lowest level of hardness, which gradually increased from the top of the hybrid layer (0 microm) through the bottom of the hybrid layer (5 microm) and into the underlying dentin ( approximately 10 microm). Significant differences in hardness were observed between the 5 microm point in the controls, the 10 microm and 15 microm points in the 100-10 group, and the 10 microm point in the 50-20 and 33-30 groups.The results suggest that laser settings affect hybrid layer thickness, even when the total energy level is constant.

This study compared surface roughness and gloss produced by different finishing/polishing procedures for two resin composites, Clearfil AP-X (AP-X) and Estelite Sigma (ES). A total of 70 composite discs (n=35 for each resin composite) were prepared and divided at random into seven finishing/polishing groups (n=5): glass-pressed control; using a super-fine-grit diamond bur (SF); using CompoMaster (CM) after SF-finishing (SF+CM); using White Point (WP) after SF-finishing (SF+WP); using CM after SF+WP-finishing (SF+WP+CM); using Stainbuster (SB) after SF-finishing (SF+SB); and using CM after SF+SB-finishing (SF+SB+CM). After the finishing/polishing procedures, average surface roughness (R(a)) and surface gloss (Gs(60( degrees ))) of all specimens were assessed with a surface profilometer and specimen gloss meter, respectively. Glass-pressed controls for both AP-X and ES composites showed the best surface finish in terms of both R(a) and Gs(60( degrees )). SF-finishing produced the roughest surface and led to almost complete loss of gloss. While additional polishing with CM reduced R(a) and increased Gs(60( degrees )), the additional finishing effect of WP or SB between SF-finishing and CM-polishing was not found for either AP-X or ES.

A new bleaching agent consisting of a titanium dioxide photocatalyst and 3.5% hydrogen peroxide has recently been developed for in-office bleaching and has proven to react well with irradiated light around a wavelength of 400 nm. This study was conducted to evaluate the efficacy of dental bleaching with a 405-nm diode laser irradiation on titanium dioxide and 3.5% hydrogen peroxide by measuring the generation of hydroxyl radicals. The amount of hydroxyl radicals generated from a titanium dioxide and 3.5% hydrogen peroxide irradiated by a 405-nm diode laser were measured using electron spin resonance spin-trapping techniques. The irradiation conditions of the laser were a spot size of 1 mm, output powers of 100, 200, 400 mW, and 600 mW, and irradiation times of 10, 20, 30, and 60 s. Nonirradiated samples were used as controls. DMPO-OH adduct spectra and DMPO-O 2 − adduct spectra were observed when the bleaching agent was irradiated by laser light. The amount of hydroxyl radicals generated changed in accordance with adjustments in the irradiation power and irradiation time. In the nonirradiated controls, hydroxyl radicals were generated in far smaller amounts. The 405-nm diode laser is effective in inducing the generation of hydroxyl radicals and shows promise as a bleaching light source for use in combination with bleaching agents composed of titanium dioxide and low concentrations of hydrogen peroxide.

The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P

Atmospheric plasma or ultraviolet (UV) treatment alters the surface characteristics of tetragonal zirconia polycrystal (TZP), increasing its hydrophilicity by reducing the contact angle against water to zero. This suggests that such treatment would increase the wettability of bonding resin. The purpose of this study was to determine how increasing the hydrophilicity of TZP through plasma irradiation, UV treatment, or application of ceramic primer affected initial bonding with resin composites. Here, the effect of each pre-treatment on the hydrophilicity of TZP surfaces was determined by evaluating change in shear bond strength. Plasma irradiation, UV, or ceramic primer pre-treatment showed no significant effect on bonding strength between TZP surfaces and resin composites. In addition, alumina blasting yielded no significant increase in bond strength. Plasma irradiation, UV treatment, or ceramic primer pre-treatment did not lead to significant increase in bond strength between TZP and resin composites.

The purpose of this study was to evaluate the tensile bond strength (TBS) to peroxide-exposed dentin. Furthermore, the effect of ascorbic acid (AA) on the bond strength of peroxide-exposed dentin was investigated. Extracted bovine dentin was exposed to 10% carbamide peroxide, 30% hydrogen peroxide, or distilled water for 30 min, then treated with 10% AA (0, 30, 90, and 180 min), and conditioned with 10% citric acid/3% ferric chloride. The polymethyl-methacrylate (PMMA) rod was bonded to the treated bovine dentin with 4-META/MMA-TBB resin. A minidumbbell-shaped bonded specimen was prepared from these bonded assemblies and the TBS was tested. The fractured surfaces were also observed with a scanning electron microscope. Exposure to peroxide before bonding significantly reduced bond strength. The application of AA to the peroxide-exposed dentin increased bond strength. On the other hand, an adverse effect of AA was found in distilled water-affected dentin. Extended resin fibers were partially seen in the peroxide-exposed dentin. In conclusion, peroxide reduced the bond strength, and the stronger the oxidation, the weaker the obtained bond. Antioxidation with AA recovered the bond strength, and this effect increased the longer the AA was applied.

This paper reviews the design challenges that current and future processors must face, with stringent power limits, high-frequency targets, and the continuing system integration trends. This paper then describes the architecture, circuit design, and physical implementation of a first-generation Cell processor and the design techniques used to overcome the above challenges. A Cell processor consists of a 64-bit Power Architecture processor coupled with multiple synergistic processors, a flexible IO interface, and a memory interface controller that supports multiple operating systems including Linux. This multi-core SoC, implemented in 90-nm SOI technology, achieved a high clock rate by maximizing custom circuit design while maintaining reasonable complexity through design modularity and reuse.

The ring-expansion reaction of equimolar cyclic dithioester 1 with 3-phenoxypropyrene sulfide (PPS) (cyclic dithioester 1/PPS = 1/2) was examined in the presence of TBAC as a catalyst in NMP for 24 h. It was found that intermolecular ester-exchange reaction occurred during the insertion reaction of PPS into cyclic dithioesters, and cyclic polymers with Mns = 3600−8900 were obtained in 80−96% yields. The structures of the obtained cyclic polymers were confirmed by the 1H NMR, 13C NMR IR, and MALDI TOF-MS spectroscopy. The continuous insertion reaction of excess PPS into cyclic dithioester (cyclic dithioester 1/PPS = 1 /50) was also examined, and it was found that the insertion reaction proceeded quantitatively to afford the corresponding cyclic polysulfide with Mn = 42 000 and Mw/Mn = 4.50 in a 96% yield.

Phosphorus-containing vinyl ether monomers and 1-propenyl ether monomers were prepared by the regioselective addition reaction of glycidyl vinyl ether (GVE) or 1-propenyl glycidyl ether with diaryl phosphonates with quaternary onium salts as catalysts. The reaction of GVE with bis(4-chlorophenyl) phenylphosphonate gave bis[1-(4-chlorophenoxy methyl)-2-(vinyloxy)ethyl]phenylphosphonate in a 68% yield. The structures of the resulting phosphorus-containing vinyl ether monomers and 1-propenyl ether monomers were confirmed by IR and 1H NMR spectra and elemental analysis. Photoinitiated cationic polymerizations of the resulting phosphorus-containing vinyl ether monomers and 1-propenyl ether monomers were investigated with photoacid generators. The polymerization of vinyl ether groups and 1-propenyl ether groups of the obtained monomers proceeded very smoothly with a sulfonium-type cationic photoinitiator, bis[4-(diphenylsulfonio)phenyl]sulfide-bis(hexafluorophosphate), upon UV irradiation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3105–3115, 2005

Fluorine-containing poly(acetal)s were synthesized by the polyaddition of bisphenol AF (BPAF) with divinyl ether compounds. It was found that the poly(acetal) (PA-1) with a number average molecular weights of 4400 was obtained in 71% yield by the polyaddition of BPAF with ethylene glycol divinyl ether (EGDVE) using 1 mol % of pyridinium p-toluene sulfonate (PTS) as a catalyst in THF at room temperature for 24 h. Furthermore, the polyaddition of BPAF with other divinyl ether compounds were also carried out to give corresponding poly(acetal)s (PA-2–PA-3) in appropriate reaction conditions. It was also found that the photoinduced depolymerization of the resulting poly(acetal)s proceeded using photo-acid generator (PAG) by the photo-irradiation in the film state. It was found that transmittance of PA-1 was 39% at 157 nm for 0.1 μm thickness.

Polyfunctional 1-propenyl ether monomers (1a–c) were synthesized by the regioselective addition reaction of 1-propenyl glycidyl ether (PGE) with certain phosphonic dichlorides using quaternary onium salts as catalysts. The reaction of PGE with phenylphosphonic dichloride (PPDC) gave bis[1-(chloromethyl)-2-(propenyloxy)ethyl]phenylphosphonate (1a) in 82% yield. Polycondensation of 1a with terephthalic acid (TPC) was also carried out using 1, 8-diazabicyclo[5.4.0]undecene-7 (DBU) as a base to afford the corresponding polymer containing 1-propenyl ether groups (2a). A multifunctional monomer (3a) containing both 1-propenyl ether groups as Vc and methacrylate groups as Vr was prepared by the reaction of 1a with methacrylic acid (MA) using DBU. Photoinitiated cationic polymerization of these 1-propenyl ether compounds proceeded rapidly using bis[4-(diphenylsulfonio)phenyl]sulfide bis(hexafluorophoshate) (DPSP), as a cationic photoinitiator without solvent upon UV irradiation.

Fluorine-containing poly(ether)s with pendant primary hydroxyl groups were synthesized by the polyaddition of bisphenol AF di(3-ethyl-3-oxetanylmethyl ether) (BPAFEO) with bisphenol AF (BPAF) using quaternary onium salts, crown ether complexes or organic bases as catalysts. When the polyaddition was performed with co-catalysts such as tetraphenylphosphonium chloride (TPPC) and 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) without solvent at 190 °C for 120 h, the corresponding poly(ether)s pendant primary hydroxyl groups were successfully obtained in good yield. The polyaddition of various bis(oxetane)s with BPAF also proceeded in bulk to provide the corresponding poly(ether)s. It was found that these poly(ether)s are highly transparent at 157 nm, and transmittance of poly(ether)s were determined to be 34–55 % at 157 nm for 0.1 μm thickness.

This study explored the abilities of 1-(9-anthrylmethyloxy)-2-pyridone and related compounds, which absorb long-wavelength light (>350 nm), to photochemically initiate radical and cationic polymerizations. It was found that the irradiation of the title compounds initiates the radical polymerization of styrene whereas the cationic polymerization of oxetane proceeds in the presence of these photoinitiators to a negligible extent. The behavior of 9-anthrylmethyloxyl and amidyl radicals in the photopolymerization process of styrene was discussed based on 1 H NMR, UV, and fluorescence spectral data. In addition, the photoinitiation ability of the anthrylmethyloxyl end group was also investigated by using its model compound.

Fluorine-containing polyethers with pendant hydroxyl groups were synthesized by the polyaddition of fluorine-containing bis(epoxide)s with certain fluorine-containing diols with quaternary onium salts as catalysts. When the polyaddition was performed with 2,2′,6,6′-tetrafluoro-4,4′-biphenol diglycidiyl ether and 2,2′,6,6′-tetrafluoro-4,4′-biphenol, the corresponding polyether with pendant hydroxyl groups was successfully obtained in good yield. The polyaddition of certain fluorine-containing bis(epoxide)s with diols also proceeded in bulk to provide the corresponding fluorine-containing polyethers with high molecular weights. These polyethers were highly transparent at 157 nm for 0.1 μm thickness, with their transmittance of 14–75% at 157 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2543–2550, 2004

The polyaddition of 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene with 2,2′-bis[(4-chloroformyl)oxyphenyl]propane was examined with quaternary onium salts as catalysts. When the polyaddition was carried out with tetrabutylphosphonium bromide in chlorobenzene at 120 °C for 24 h, the corresponding poly(alkyl aryl carbonate) with a high molecular weight (number-average molecular weight = 16,700) was obtained in an almost quantitative yield. It was found from the 1H NMR and 13C NMR spectra of the obtained polymer that the addition reaction proceeded without any side reactions, providing the polycarbonate with pendant chloromethyl groups in the side chain. The polyaddition of bis{[3-(3-ethyloxetanyl)]methyl}terephthalate also proceeded smoothly and gave the corresponding polycarbonate with high molecular weight in a good yield. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2304–2311, 2003

We have studied synthesis and solid-state ring-opening polymerization of macrocyclic S-aryl thioesters, dimer p-BBDT-2, trimer p-BBDT-3, and tetramer p-BBDT-4 containing terephthaloyl structure. The targeted p-BBDT-2, p-BBDT-3, and p-BBDT-4 were prepared by the reaction of terephthaloyl chloride (TPC) with 4- tert-butyl-1,2-benzenedithiol (BBDT) using NaOH under phase transfer conditions. The macrocyclic trimer p-BBDT-3 was obtained preferentially in 81% yield by a reaction at a concentration of 1.0 mol 1-1 in a mixture of aqueous NaOH and chloroform. The structures of the prepared macrocyclic S-aryl thioesters were well identified by IR, 1H NMR, 13C NMR spectroscopies, MALDI-TOF MS, and elemental analysis. The solubility and thermal properties of p-BBDT-2, p-BBDT-3, and p-BBDT-4 were characterized. It was found that the ring-opening polymerization of p-BBDT-2, p-BBDT-3, and p-BBDT-4 without catalysts occurred in the solid state, and the corresponding poly( S-aryl thioester)s with moderate molecular weights were obtained. The behaviors of the polymerization of p-BBDT-3 and catalytic effect of potassium halides/dibenzo-18-crown-6 complexes were examined. It was also found that the poly( S-aryl ester) obtained by a solid-state polymerization had good thermal properties.

In this study, using a prototype Er:YAG laser of which pulse repetition rate can be adjusted up to 30 pps, we histopathologically investigated the damage to pulpal response at the time of cavity preparation in relation to the pulse repetition rate. After the Beagle dogs received systemic anesthesia, a contact tip of 600 μm in fiber diameter was placed in the Er:YAG laser and a Black's V cavity was prepared under the following radiation conditions with watering. After cavity preparation was completed, the interior of the cavity was cleansed and filled with a hydraulic sealing material. Observation periods lasted both 7 and 28 days. Paraffin sections were obtained via a conventional method, stained with a double-staining of hematoxylin and eosin, and histopathologically investigated for changes in the pulp under a microscope. In both the 7th and 28th day follow-up observation cases, circular disorders such as vasodilation and hemorrhage were found at a high rate in both groups, although inflammatory changes such as infiltration of round cells were few. Under the radiation conditions set in this experiment, it was confirmed that cutting of the dental hard tissue could be made without severe changes to the pulp. Because the pulse repetition rate can be changed, we will be able to study in detail the cutting efficiency with changes in the width of the radiation conditions at various cutting sites, such as the dental enamel, dentine and soft dentine.

The purpose of this study was to evaluate performance in oral soft tissue surgery and the periodontal tissue interactions resulting from increasing the repetition rate of a pulsed-mode Er:YAG laser system from 10 to 30 pulses per second (pps). Five beagle dogs aged 2 or 3 years old were used in this study. The specific maneuvers were performed for a gingivectomy and the removal of melanin pigmentation. A trial Er:YAG laser, which is adjustable up to 30 pps of repeated rate, was used. As for gingivectomy, the output power was made under eight conditions (35 mJ–30 pps, 35 mJ–20 pps, 70 mJ–10 pps, 70 mJ–20 pps, with or without water). The irradiation condition for the removal of melanin pigment was set at 35 mJ–30 pps with or without water. The observation periods were immediately, 7 and 28 days. Specimens were made and observed under a light microscope. Procedures of the gingivectomy and removal of melanin pigmentation resulted in favorable healing, regardless of the irradiation conditions. Increasing the repetition rate up to the 30 pps with low power significantly improved the smoothness and morphology. The high-repetition-rate Er:YAG laser technology described is advantageous, compared with low-repetition-rate Er:YAG lasers, and is applicable in a variety of oral soft tissue surgical procedures.

This paper reviews our recent studies on the syntheses and functions of novel calixarene derivatives with excellent thermal stability as high performance materials. Calixarene derivatives containing protective groups such as tert-butoxycarbonyl (t-Boc), trimethylsilyl (TMS), and cyclohexenyl (CHE) groups were successfully prepared by the reaction of certain calixarenes, p-methylcalix[6]arene (1a), p-tert-butylcalix[8]arene (1c), and C-methylcalix[4]resorcinarene (1d) with the corresponding protecting reagents. Calixarene containing radically polymerizable groups such as methacryloyl groups and cationic polymerizable groups such as propargyl, vinyl ether groups were prepared in good yields. Calixarene derivatives containing cyclic ethers such as oxirane, oxetane, and spiro orthoesters were also prepared. Calixarene derivatives thus obtained had good film forming property and thermal stability. It was proved that the photoinduced deprotection of the calixarene derivatives containing protective groups in the presence of a photo-acid generator proceeded easily to give the corresponding calixarenes with phenol groups. Photoinitiated polymerization of the calixarenes with various polymerizable groups using suitable photoinitiators in the film state proceeded efficiently to produce crosslinked films. Furthermore, thermal curing of epoxy resins with calixarenes (1a, 1c, 1d), and calixarenes containing active ester groups using certain catalysts were studied to found that the calixarenes were useful curing agents for epoxy resins.

The donor–acceptor type norbornadiene (D–A NBD) carboxylic acids containing carbamoyl groups such as dipropylcarbamoyl, methylphenylcarbamoyl, propylcarbamoyl, and phenylcarbamoyl groups were synthesized in good yields. Benzyl esters of the D–A NBD carboxylic acids were also prepared by the reaction of D–A NBD carboxylic acids with benzyl bromide as reference compounds for the polymers. Polystyrenes with pendant D–A NBDs were prepared with 100% degree of substitution by the reaction of D–A NBD carboxylic acids and poly[( p -chloromethyl)styrene] at 70 °C for 6 h using 1,8-diazabicyclo[5.4.0]undecene-7 as a base in N -methylpyrrolidone. The photochemical valence isomerizations of the reference compounds and all the NBD polymers were examined upon UV-irradiation in THF solution or in the film state, and it was found that the polymer containing phenylcarbamoyl group had especially high photoreactivity. In addition, the rate of the photochemical reaction of the NBD polymers increased efficiently by the addition of 4,4′-bis(diethylamino)benzophenone as photosensitizer in the film state, and all the NBD groups of the polymers isomerized to the QC group in as little as only 20 s. The stored thermal energy of the irradiated polymers was also evaluated by DSC to be 32–52 kJ/mol.

The synthesis and optical properties of polyesters with pendant fluorinated phenoxy groups were examined. The polyaddition of bisphenol AF diglycidyl ether (1) with fluorine-containing terephtalates (2a–f) was carried out with tetrabutylphosphonium chloride (TBPC) as the catalyst in chlorobenzene to afford the corresponding polyesters with number-average molecular weights (Mn's) ranging from 15,200 to 30,000 in 88–96% yields. Furthermore, the polyaddition of 1 with isophthalate 2g and phthalate 2h also produced high-molecular-weight polyesters with Mn's = 22,700 and 22,600 in 88 and 84% yields, respectively. The linear relationship was observed between the fluorine contents and refractive indices of the obtained polyesters. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 213–222, 2003

The polyaddition of 4,4′-bis[(3-ethyl-3-oxetanyl)methoxy]biphenyl (4,4′-BEOBP) and phenylphosphonic dichloride (PPDC) with quaternary onium salts as catalysts proceeded under mild reaction conditions to afford a polymer containing phosphorous atoms in its main chain. A polyphosphonate with a high number-average molecular weight (10,300) was obtained by the reaction of 4,4′-BEOBP and PPDC in the presence of tetraphenylphosphonium chloride (TPPC) in o-dichlorobenzene at 130 °C for 24 h. The structure of the resulting polymer was confirmed with IR, 1H NMR, and 31P NMR spectroscopy. Furthermore, it was proved that the polyaddition of certain bis(oxetane)s with phosphonic dichlorides proceeded smoothly to give corresponding polyphosphonates with TPPC as the catalyst. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3835–3846, 2002

The synthesis and characterization of the fluoropolymers poly1a–1d and poly2a–2d with pendant hydroxyl groups were examined. The polyaddition of bis(epoxide)s [2,2′-bis(4-glycidyletherphenyl)hexafluoropropane and bisphenol A diglycidyl ether] with dicarboxylic acids (tetrafluoroterephthalic acid and terephthalic acid) and diols [2,2′-bis(4-hydroxyphenyl)hexafluoropropane, 2,2′,3,3′,5,5′,6,6′-octafluoro-4,4′-biphenol, 1,4-bis(hexafluorohydroxyisopropyl)benzene, and 1,3-bis(hexafluorohydroxyisopropyl)benzene] was carried out at 50–100 °C for 6–48 h in the presence of quaternary onium salts (tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylphosphonium bromide, and tetrabutylphosphonium chloride; 2.5 mol %) as catalysts in dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dioxane, diglyme, o-dichlorobenzene, chlorobenzene, and toluene to afford the corresponding polymers, poly1a–1d and poly2a–2d, with number-average molecular weights of 11,000–59,400 in 45–97% yields. The solubility of the obtained polymers was good, and their thermal stability might be assumed from their structures. A linear relationship was observed between the contents of the fluorine atoms and the refractive indices. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1395–1404, 2002

New photoreactive calixarene derivatives containing spiro ortho ester groups (calixarenes 3a-3c) were synthesized by the reaction of 2-bromomethyl-1,4,6-trioxaspiro[4.4]nonane with 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octakis(carboxymethoxy)calix[4]resorcinarene, 5,11,17,23,29,35-hexamethyl-37,38,39,40,41,42-hexakis-(carboxymethoxy)calix[6]arene, and 5,11,17,23,29,35,41,47-octa-tert-butyl-49,50,51,52, 53,54,55,56-octakis-(carboxymethoxy)calix[8]arene, which were prepared by the reaction of C-methylcalix[4]resorcinarene, p-methylcalix[6]arene, and p-tert-butylcalix[8]arene, respectively. The thermal stability of the obtained calixarene derivatives containing spiro ortho ester groups was examined with thermogravimetric analysis, and it was found that these calixarene derivatives had good thermal stability. The photoinitiated cationic polymerization of spiro ortho ester groups in calixarene derivatives 3a-3c was examined with certain photoacid generators in the film state. Interestingly enough, the reaction of calixarene derivatives did not proceed with only photoirradiation; however, the reaction proceeded smoothly when the photoirradiation was followed by heating. Furthermore, calixarene 3a, composed of a C-methylcalix[4]resorcinarene structure, showed the highest photochemical reactivity in this reaction system.

Linear and branched polymers bearing S-(2-benzoxazolyl) thioester groups were selectively synthesized by free radical and photoinitiated radical polymerization, respectively, of S-(2-benzoxazolyl)-...

Many patients presenting at oral malodor clinics have psychological halitosis, which is characterized as being obsessive about having oral malodor or being distressed from a keen awareness of oral odor. We used the Tokyo University Egogram (TEG) to evaluate personality traits in patients presenting at the oral malodor clinic of this institute. The incidence of each TEG personality type was compared between a total of 600 patients presenting at the clinic and a cohort of healthy individuals. Differences were found between the malodor patient and healthy groups. Nurturing Parent (NP)-dominant, Adult (A)-dominant, inverse N (NP low, Free Child high), showed a significant decrease of 6.7, 11.3, and 3.6%, respectively; whereas N (A low) and N (NP high, Free Child low) showed a significant increase of 3.3 and 6.4%, respectively (p < 0.01).

Career paths and aspirations were investigated among postgraduate dental trainees on completion of clinical training at Tokyo Dental College between 2006, when clinical residency became mandatory, and 2011. Overall, those finding employment with independent general dental practitioners accounted for the majority (34%), followed by those entering postgraduate courses at the Chiba Hospital (20%), those embarking on a postgraduate clinical specialty course at the Chiba Hospital (16%), and those going on to other universities (7%). At the Chiba Hospital, the number selecting postgraduate courses, residency training (including further residency training or a postgraduate clinical specialty course), or employment with a general dental practitioner was almost the same; however, the number selecting postgraduate courses at the Suidobashi Hospital was low, showing a strong tendency toward becoming a general or clinical practitioner. At the Ichikawa General Hospital, most of the trainees decided to remain at the same school or hospital as postgraduate students or residents, showing an aspiration toward further specialization. The results of the Fisher's exact test showed a significant difference in career paths between the Chiba, Suidobashi, and Ichikawa General Hospitals. Trends among postgraduate dental trainees from this and other schools completing the clinical residency program here and subsequently entering postgraduate courses, further residency training, or a postgraduate clinical specialty course at this school were investigated. No major difference was observed in the percentage of trainees remaining at the same school or entering postgraduate courses between those from this and those from other schools; however, more trainees from other schools selected further residency training, while fewer selected a postgraduate clinical specialty course.

The purpose of this study was to evaluate the combined effects of citric acid and glutaraldehyde (GA) on the resin bonding to Er: YAG laser-irradiated dentin. Bovine dentin was prepared with 180- to 600-grit SiC paper and then uniformly irradiated with an Er: YAG laser (laser-irradiated group) or immersed in water at 60 degrees C for 15 min (heated group). The samples were then acid-conditioned with 10% citric acid (10-0) or 10% citric acid/3% ferric chloride (10-3) for 15 s and treated with GA for 10 min before bonding to an acrylic rod with 4-META/MMA-TBB resin. These samples were trimmed to prepare miniaturized dumbbell-shaped specimens. After storage in water at 37C for 1 d, the tensile bond strength was measured, and the fractured surface was evaluated using a scanning electron microscope (SEM). In the laser-irradiated and heated groups, the 10-3+GA-treated specimen had higher bond strength than that of 10-0+GA. On the other hand, the tensile bond strength of 10-3 +GA in the non-irradiated group was lower that that of 10-0+GA. In conclusion, the combination of 10-3 and GA for bonding with 4-META/MMA-TBB resin was the most effective for Er: YAG laser-irradiated dentin and heated dentin, but it was not effective for the non-irradiated dentin.

Thermal polymerizations of macrocyclic S-aryl thioester trimer with a 5- t-butylisophtaloyl skeleton ( m-CTE-3) were investigated. The polymerization of m-CTE-3 without catalysts occurred at over 260°C in the solid state and heating at 280°C for 10 min produced a polymer with a Mw of 370 000. Quaternary onium salts or crown ether complexes enhanced the solid-phase thermal polymerization of m-CTE-3. In the case of the polymerization using 18-crown-6 ether (18-C-6)/potassium halide complexes, the polymerization occurred at around 200°C. It was proved that 18-C-6/KBr was the most effective catalyst to produce high molecular weight polymers with Mw as much as 850 000. It was also suggested that the solid-phase polymerization proceeded in a chain-growth reaction mode.

The synthesis of poly(carbonate)s with phenoxymethyl groups in their side chains by a polyaddition of bisphenol A diglycidyl ether (4a) with diphenyl carbonate (2) using quaternary onium salts or c...

Polyesters containing donor−acceptor norbornadiene (D−A NBD) residues in the main chain were synthesized by the polyaddition of D−A NBD dicarboxylic acids, 5-(4-methoxyphenyl)-1,4,6,7,7-pentamethyl-2,5-norbornadiene-2,3-dicarboxylic acid and 5,6-bis(4-methoxyphenyl)-7,7-dimethyl-2,5-norbornadiene-2,3-dicarboxylic acid, with bis(epoxide)s. The photoisomerization of the NBD residues in the resulting polyesters proceeded smoothly to give the corresponding quadricyclane (QC) groups. The NBD residues in these polyesters showed resistivity to repeated cycles of the interconversion.

New photoreactive calixarene derivatives containing cationically polymerizable pendant oxetane groups (calixarenes la,b, 2a,b, and 3a,b) were synthesized in good yields by the substitution reaction of C-methylcalix[4]resorcinarene (CRA), p-methylcalix[6]arene (MCA), and p-tert-butylcalix[8]arene (BCA) with (3-methyloxetan-3-yl)methyl 4-toluenesulfonate and (3-ethyloxetan-3-yl)methyl 4-toluenesulfonate with potassium hydroxide as a base and tetrabutylammonium bromide as a phase-transfer catalyst in N-methyl-2-pyrrolidone, respectively. Calixarene derivatives containing cationically polymerizable pendant oxirane groups (calixarenes 4, 5, and 6) were also prepared in good yields by the substitution reaction of CRA, MCA, and BCA with epibromohydrin, respectively, with cesium carbonate as a base in N-methyl-2-pyrrolidone. The thermal stability of the obtained calixarene derivatives containing pendant oxetane groups or oxirane groups was examined with thermogravimetric analysis, and it was found that these calixarene derivatives had thermal stability beyond 340 °C. The photochemical reaction of calixarenes 1, 2, and 3 containing pendant oxetane groups was examined with certain photoacid generators in the film state. In this reaction system, calixarene la, composed of a CRA structure and pendant (3-methyloxetan-3-yl)methyl groups, showed the highest photochemical reactivity when bis-[4-(diphenylsulfonio)phenyl]sulfide bis(hexafluorophosphate) was used as the catalyst. The photochemical reaction of calixarenes 4, 5, and 6 containing pendant oxirane groups was also examined, and it was found that the photoinitiated cationic polymerization of calixarenes 4, 5, and 6 proceeded smoothly under the same conditions; however, the reaction rates were lower than those of the corresponding calixarenes 1, 2, and 3 containing pendant oxetane groups.

Novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups were synthesized by the one-pot method for the reaction of poly(methacrylic acid) with epibromohydrin; this was followed by a reaction with phenacylbromide with 1,8-diazabicyclo-[5.4.0]undecene-7 as a condensation reagent. These esterification reactions proceeded smoothly and quantitatively under mild conditions. Moreover, the photochemical reactions of the resulting polymers were evaluated by UV and IR spectroscopy. The pendant phenacyl ester groups were photocleaved to give corresponding carboxyl groups, and then the produced carboxyl groups reacted with pendant epoxy groups. Furthermore, the baking process promoted a crosslinking reaction because of the addition reaction of epoxy groups with carboxyl groups after irradiation. It was also proven that the photochemical reactivity of the resulting polymers was affected by the structure of the phenacyl ester group. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 530–538, 2001

The donor–acceptor-type norbornadiene (D–A NBD) 1,4,5,6-tetramethyl-3-phenyl-2,5-NBD-2-carboxylic acid was prepared by the Diels–Alder reaction of methyl 3-phenylprop-2-ynoate with 1,2,3,4-tetramethyl-1,3-cyclopentadiene. 1,4,5,6,7-Pentamethyl-3-phenyl-2,5-NBD-2-carboxylic acid was also synthesized in the same way. Styrene-type polymers with pendant D–A NBD moieties were prepared with a 100% degree of substitution (DS) by the reaction of D–A NBD carboxylic acids with poly[(p-chloromethyl)styrene] with 1,8-diazabicyclo[5.4.0]undecene-7 in dimethyl sulfoxide at 70 °C for 6 h. In the reaction of D–A NBD carboxylic acids with poly(2-chloroethyl vinyl ether), the DSs were about 60%. The photochemical valence isomerizations of all the NBD polymers proceeded smoothly with UV irradiation in tetrahydrofuran solutions and in the film state. In addition, the rate of the photochemical reaction of the NBD polymers increased efficiently by the addition of 4,4′-bis(diethylamino)benzophenone as a photosensitizer in a film state. The stored thermal energy of the irradiated polymers was also evaluated by differential scanning calorimetry to be 55–74 kJ/mol. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1764–1773, 2001

Calixarene derivatives 1a, 1b, and 1c containing pendant tert-butoxycarbonyl (t-BOC) groups were synthesized in 81, 93, and 83% yields, respectively, by the reaction of C-methylcalix[4]resorcinarene (CRA), p-methylcalix[6]arene (MCA), and p-tert-butylcalix[8]arene (BCA) with di-tert-butyl dicarbonate using triethylamine as a base in pyridine. Calixarene derivatives 2a, 2b, and 2c containing pendant trimethylsilyl ether (TMSE) groups were obtained in 58, 50, and 82% yields, respectively, by the reaction of CRA, MCA, and BCA with 1,1,1,3,3,3-hexamethyldisilazane using chlorotrimethylsilane as an accelerator in tetrahydrofuran. Calixarene derivatives 3a, 3b, and 3c containing pendant cyclohexenyl ether (CHE) groups were also prepared in 65, 78, and 84% yields, respectively, by the reaction of CRA, MCA, and BCA with 3-bromocyclohexene using potassium hydroxide as a base as well as tetrabutylammonium bromide as a phase-transfer catalyst in N-methyl-2-pyrolidone. The photoinduced deprotection of calixarene derivatives 1a–c was examined with bis-[4-(diphenylsulfonio)phenyl]sulfide bis(hexafluorophosphate) as a photoacid generator on UV irradiation followed by heating in the film state, and it was found that the deprotection of the t-BOC groups of 1a proceeded smoothly in high conversion. The deprotection rates of the t-BOC groups of 1b and 1c were much lower than that of 1a under the same irradiation conditions. The photoinduced deprotection of calixarenes 2b–c containing tetramethylsilane groups as well as 3a–c containing CHE groups were also examined under similar reaction conditions in the film state, and it was found that the deprotection rates of calixarenes 2b–c and 3a–c were lower than those of the corresponding 1a–c calixarenes. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1481–1494, 2001

A donor–acceptor norbornadiene derivative, 5-(4-methoxyphenyl)-1,4,6,7,7-pentamethyl-2,5-norbornadiene-2,3-dicarboxylic acid diglycidyl ester (D–A NDGE), was synthesized by the reaction of the cesium salt of 5-(4-methoxyphenyl)-1,4,6,7,7-pentamethyl-2,5-norbornadiene-2,3-dicarboxylic acid with epibromohydrin in N-methyl- pyrrolidone (NMP). The polyaddition reactions of D–A NDGE with certain dicarboxylic acids were carried out with tetrabutylammonium bromide as a catalyst in NMP, producing corresponding polyesters containing D–A norbornadiene (NBD) residues in the main chain in fair to good yields. The photoisomerization of the D–A NBD residues in the polyesters proceeded very smoothly, forming the corresponding quadricyclane groups. The photoreactivities of the D–A NBD residues in the polymer were 50 times higher than those of the NBD residues in the film state and 60 times higher than those in a tetrahydrofuran solution. The stored energy in the quadricyclane groups of the polymers was about 45–55 kJ/mol according to differential scanning calorimetry analysis of the irradiated polymer films. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2683–2690, 2001

Polyethers with unsymmetrical structures in the main chains and pendant chloromethyl groups were synthesized by the polyaddition of 3-ethyl-3-(glycidyloxymethyl)oxetane (EGMO) with certain diacyl chlorides with quaternary onium salts or pyridine as catalysts. The unsymmetrical polyaddition of EGMO containing two different cyclic ether moieties such as oxirane and oxetane groups with terephthaloyl chloride proceeded smoothly in toluene at 90 °C for 6 h to give polymer 1 with a number-average molecular weight (Mn) of 51,700 in a 93% yield when tetrabutylammonium bromide (TBAB) was used as a catalyst. The polyaddition also proceeded smoothly under the same conditions when other quaternary onium salts, such as tetrabutylammonium chloride, tetrabutylammonium iodide, tetrabutylphosphonium chloride, and tetrabutylphosphonium bromide, and pyridine were used as catalysts. However, without a catalyst no reaction occurred under the same reaction conditions. Polyadditions of EGMO with isophthaloyl chloride and adipoyl chloride gave polymer 2 (Mn = 28,700) and polymer 3 (Mn = 25,400) in 99 and 65% yields, respectively, under the same conditions. The chemical modification of the resulting polymer, polymer 1, which contained reactive pendant chloromethyl groups, was also attempted with potassium 3-phenyl-2,5-norbornadiene-2-carboxylate with TBAB as a phase-transfer catalyst, and a polymer with 65 mol % pendant norbornadiene moieties was obtained. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 368–375, 2001