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Random copolymers bearing triethanolamine borate (TEAB) groups in the side chains were investigated as the first example of boratrane-containing polymers. The title polymers were synthesized via tw...

Polyhedral oligomeric silsesquioxane (POSS) is a versatile building block for various organic/inorganic hybrid materials. However, its intrinsic reactivity has attracted limited attention, particularly in polymer chemistry. This study investigated the cage-scrambling properties of POSS-pendant random copolymers catalyzed by fluoride anions, leading to gelation of a solution of random copolymers. A series of POSS-pendant random copolymers was prepared using POSS-containing methacrylates and several vinyl monomers. The gelation properties were first investigated in detail using P(PhPOSSMA-r-BMA) by varying the POSS content and reaction conditions. The insoluble product was characterized by FT-IR and solid-state 29Si-NMR, the results of which support the intermolecular cage-scrambling reaction of the pendant POSS moieties via transient siloxane cleavage. Chloride and bromide anions also acted as catalysts for the scrambling reaction. Altering the comonomer or the vertex substituents resulted in varying gelation times depending on each structural characteristic. The unique polymer reaction presented herein opens up a wider range of uses for POSS—not only as an inorganic component but also as an intrinsically reactive moiety in various organic/inorganic hybrid polymer materials. Fluoride anions-catalyzed cage scrambling and gelation of POSS-pendant random copolymers was investigated. A series of POSS-pendant random copolymers was prepared using POSS-containing methacrylates and several vinyl monomers. FT-IR, solid-state 29Si-NMR, and swelling experiments of the gelation products showed that the pendant POSS groups underwent intermolecular cage-scrambling reaction, which proceeds via transient siloxane cleavage. Chloride and bromide anions also catalyzed the scrambling reaction under modified reaction conditions. Gelation properties depended on various factors such as the comonomers, reaction solvents, vertex substituents, POSS contents, and catalyst feeds.

As a new example of intrinsically water-triggered phenomena, we report underwater dehydration of the statistical copolymers synthesized from triethanolamine borate (TEAB) methacrylate and styrene (St) induced by the hydrolysis of the pendant TEAB group. TEAB possesses high polarity owing to its internal Lewis adduct structure, which is lost by hydrolysis to triethanolamine (TEA) with a lower dipole moment. Therefore, the hydration of the copolymers became unfavorable through the hydrolysis of the pendant TEAB to TEA, despite polyol formation, and through a hydrophobic interaction based on St moieties becoming alternatively dominant. The dehydration behavior of the copolymers, along with the hydrolysis of the pendant TEAB group, was systematically investigated. The water solubility of the copolymers was found to be dependent on the gradient of the hydrolysis equilibrium of TEAB on the side chains and was the lowest for the TEA state. These findings offer a novel concept toward designing water-responsive materials.

We report the novel thioacyl-transfer ring-expansion polymerization (REP) of thiiranes, using 3H-benzothiazol-2-thione (BTT) as the cyclic dithiocarbamate initiator and tetrabutylammonium chloride ...

The aim of this study was to evaluate the physico-mechanical properties of a new cavity base material containing mineral trioxide aggregate, LA-T1, prototyped by Neo Dental Chemical Products for indirect restoration. Three base materials, LA-T1, Cavios (CAV, Neo Dental Chemical Products), and Bulk Base Hard (BBH, Sun Medical), were examined. The depth of cure, microshear bond strength with a resin-based luting cement, and the compressive strength of these materials were investigated. The depth of cure of LA-T1 was similar to that of CAV, while the depth of cure of BBH was above the measurement limit. The distance from the base material to the light source, 0 mm and 4 mm, did not significantly affect the depth of cure of all materials. The microshear bond strength of LA-T1 bonded to a resin-based luting cement was slightly higher than that of CAV and similar to that of BBH, both of which were bonded to the same luting cement under the same conditions. The compressive strength of LA-T1 was similar to that of CAV but less than that of BBH. The results of this study indicate that LA-T1 has properties that are similar to those of CAV and thus can be clinically applied.

Ring‐expansion polymerization (REP) of thiiranes was investigated using 3H‐benzothiazol‐2‐one (BT) as the cyclic aromatic thiourethane initiator in the presence of tetrabutylammonium chloride (TBAC) catalyst. The polymerization proceeded in a well‐controlled manner to afford cyclic polysulfides with one BT moiety per macrocycle, as confirmed by MALDI‐TOF MS spectroscopy. Differential scanning calorimetry (DSC) measurement of the obtained cyclic polysulfides revealed slight decrease in the glass‐transition temperature as the increase in the molecular weight, supporting the cyclic topology of the products. Postpolymerization of thiiranes using the BT‐initiated cyclic polysulfide as the macroinitiator afforded the ring‐expanded product while maintaining the narrow polydispersity and well‐defined cyclic structure, which enabled precise synthesis of cyclic block copolymer with different thiirane combination. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2442–2449

The aim of this study was to evaluate the influence of solvent evaporation on the ultimate tensile strength (UTS) of commercial adhesives. Two 1-step (OptiBond All-In-One and G-Premio Bond) and two 2-step (Clearfil SE Protect, OptiBond XTR) adhesives were selected. Two bottles of each adhesive were opened and stored at 37 °C in a dry oven with silica gel shielded from light for 2 weeks (“Desiccated”). Two unopened bottles were stored at room temperature (“Original”). After 2 weeks, the adhesives were used to fill an hour-glass shaped, metallic matrix mold and light-cured. Samples were weighed, and then immersed in a 37 °C water bath for 1 h or 7 days. The UTS of each sample was then measured at a cross-head speed of 1 mm/min (n = 10). The UTS for the Clearfil SE Protect was higher in the “Original” than “Desiccated” samples (p 0.05). Neither of the two “Original” 1-step samples could be hardened, even after light-curing, yet the ‘Desiccated’ OptiBond All-In-One samples obtained high UTS values. Both OptiBond All-In-One and Clearfil SE Protect had an increase in weight after the 7-day immersion in water. In conclusion, residual solvent reduces the mechanical strength of the adhesive. The hydrophilicity of the adhesive resin might also affect its mechanical strength.

Background: The present study aimed to examine the impact of “curricula for undergraduate education in oriental medicine (OM)/complementary and alternative medicine (CAM)” on student awareness of OM. A questionnaire survey was conducted involving the Nagasaki University School of Dentistry (NUSD), a university that implements education in OM as part of its undergraduate curriculum, and Tokyo Dental College (TDC), which does not teach OM. Materials and methods: The third- and fifth-year students of both NUSD and TDC underwent the anonymous questionnaire survey, which included questions regarding their knowledge of OM and CAM, interests in these subjects, and their opinions on the necessity of teaching OM in the undergraduate dental education, and the results were collected for analysis. Results: Whereas 33% of 5th year NUSD students had knowledge of OM/CAM was 33%, only 10% of 5th year TDC students reported knowledge on the subject. 69% of 5th year NUSD students interested in OM/CAM, while 5th year TDC students who interest them were only 45%. Although 77% of 5th year NUSD students were in favor of OM education implemented in the Faculty of Dentistry, the percentages of TDC students of that were smaller (46% in 3rd year and 48% in 5th year). Whereas 26% of 5th year TDC students did not recognize the necessity of oriental medicine education, only one 5th year NUSD student (2%) did not so. Conclusion: Introduction of education in OM in the undergraduate dental education program helps students to increase their interests in dental clinical applications., African Journal of Traditional, Complementary and Alternative Medicines, 14(3), pp.287-295; 2017

Synthesis of a series of diblock copolymers consisting of POSS-containing random methacrylate copolymers and polystyrene (P(MAPOSS-r-methyl methacrylate)-b-polystyrene etc.) has been established by reversible addition–fragmentation chain-transfer (RAFT) polymerisation. The polymerisation of styrene as the second block was well controlled when POSS-containing random copolymers were used as the chain transfer agent (CTA). Dynamic cross-linking of POSS-containing block copolymers, which utilized a cage scrambling reaction among pendant POSS units mediated by a fluoride ion, was achieved by evaporating the solvent from a solution of block copolymers tetrabutylammonium fluoride (TBAF) and 1,4-bis(triethoxysilyl)benzene (BTSB) in THF. During the solvent evaporation and thermal annealing that provided cross-linked polymer films, a phase-separated structure was formed. The microphase-separated structure of the cross-linked block copolymers showed the cylindrical morphology of the POSS-containing blocks, which was proved by small angle X-ray scattering (SAXS) measurements and transmission electron microscopy (TEM) observations. A clear microphase-separated structure was obtained when a larger amount of fluoride ions was used for cage scrambling. The morphology was maintained even after immersing in tetrahydrofuran, indicating that the phase-separated structure was completely immobilized by cross-linking.

A block copolymer consisting of a photo-decomposable polyurethane and poly(methyl methacrylate) (PMMA) was developed. The end-functionalized polyurethane (P2) was synthesized by polycondensation with the end-functionalization reagents. P2 possesses the photosensitive o-nitrobenzyl group and the 2-bromoisobutyryl group as the initiator of the atom transfer radical polymerization (ATRP). The block copolymer (P2-b-PMMA) was synthesized by the ATRP of methyl methacrylate (MMA) with P2 as the macroinitiator. The P2 block in P2-b-PMMA was decomposed by photo-irradiation at 365 nm by the initiation of the photo-fries rearrangement of the urethane linkage and the subsequent domino reaction consistent with the elimination of the aza-quinone methide and decarboxylation. The photo-initiated decomposition of the P2 segment in the thin-film state was accomplished.

This study aimed to examine the marginal seal between various commercial temporary restorative materials and exposed dentin/built-up composite. Sixty bovine incisors were cut above the cemento-enamel junction, and half of the dentin was removed to form a step, which was built up using flowable resin composite. The root canals were irrigated, filled with calcium hydroxide, and sealed using one of six temporary sealing materials (hydraulic temporary restorative material, temporary stopping material, zinc oxide eugenol cement, glass-ionomer cement, auto-cured resin-based temporary restorative material, and light-cured resin-based temporary restorative material) (n = 10 for each material). The samples were thermocycled 500 times and immersed in an aqueous solution of methylene blue. After 2 days, they were cut along the long axis of the tooth and the depth of dye penetration was measured at the dentin side and the built-up composite side. For the margins of the pre-endodontic resin composite build-up, the two resin-based temporary restorative materials showed excellent sealing. Hydraulic temporary restorative material had a moderate sealing effect, but the sealing effect of both zinc oxide eugenol cement and glass-ionomer cement was poorer.

This in vitro study aimed to clarify the combined effect of electric toothbrushing and dentifrice on the removal of artificial stain. Twenty-five bovine incisors were cut at the cervix and the crown was embedded in auto-cured acrylic resin. Specimens were abraded using #240 SiC paper to obtain a flat enamel surface, and 20 specimens were treated with 10% citric acid / 3% ferric chloride solution followed by 1% tannic acid solution to produce surface staining. They were divided into four groups: 1) brushing with an electric toothbrush and whitening dentifrice (group S+B); 2) brushing with an electric toothbrush and fluoride dentifrice (group S+C); 3) brushing with an electric toothbrush and no dentifrice (group S); and 4) no brushing (control group). The remaining five specimens were used as a baseline. Color values (L*, a*, and b* were measured before brushing (0 min), and at 1 min, 5 min, 10 min, and 20 min using a microscopic area spectrophotometer. The color change (?E) was calculated by subtracting the baseline values from the final color values obtained at each time point. The data were statistically analyzed using two-way repeated-measures analysis of variance and Tukey?s honest significant difference test as a post hoc test (p0.05). Groups S+B and S+C demonstrated greater ?E values than group S. The combination of electric toothbrushing and dentifrice removed the artificial stain more effectively than brushing without dentifrice. However, the stain removal was limited. The two dentifrices evaluated in this study exhibited similar stain removal effects.

Here we report the facile network formation of a methacrylate polymer containing polyhedral oligomeric silsesquioxane (POSS) in the side chain by a dynamic cage-scrambling reaction mediated by fluo...

Background This in vitro study aimed to clarify the combined effect of electric toothbrushing and dentifrice on the removal of artificial stain. Material and Methods Twenty-five bovine incisors were cut at the cervix and the crown was embedded in auto-cured acrylic resin. Specimens were abraded using #240 SiC paper to obtain a flat enamel surface, and 20 specimens were treated with 10% citric acid / 3% ferric chloride solution followed by 1% tannic acid solution to produce surface staining. They were divided into four groups: 1) brushing with an electric toothbrush and whitening dentifrice (group S+B); 2) brushing with an electric toothbrush and fluoride dentifrice (group S+C); 3) brushing with an electric toothbrush and no dentifrice (group S); and 4) no brushing (control group). The remaining five specimens were used as a baseline. Color values (L*, a*, and b* were measured before brushing (0 min), and at 1 min, 5 min, 10 min, and 20 min using a microscopic area spectrophotometer. The color change (ΔE) was calculated by subtracting the baseline values from the final color values obtained at each time point. The data were statistically analyzed using two-way repeated-measures analysis of variance and Tukey’s honest significant difference test as a post hoc test (p0.05). Groups S+B and S+C demonstrated greater ΔE values than group S. Conclusions The combination of electric toothbrushing and dentifrice removed the artificial stain more effectively than brushing without dentifrice. However, the stain removal was limited. The two dentifrices evaluated in this study exhibited similar stain removal effects. Key words:Color change, stain removal, dentifrice, electric toothbrush, whitening effect.

Background This study aimed to evaluate the effect of dental prophylaxis on the surface gloss and roughness of different indirect restorative materials for computer-aided design/computer-aided manufacturing (CAD/CAM): two types of CAD/CAM composite resin blocks (Shofu Block HC and Estelite Block) and two types of CAD/CAM ceramic blocks (IPS Empress CAD and Celtra DUO). Material and methods After polishing the CAD/CAM blocks and applying prophylaxis pastes, professional dental prophylaxis was performed using four different experimental protocols (n = 5 each): mechanical cleaning with Merssage Regular for 10 s four times (Group 1); four cycles of mechanical cleaning with Merssage Regular for 10 s and Merssage Fine for 10 s (Group 2); four cycles of mechanical cleaning with Merssage Regular for 10 s and Merssage Fine for 30 s (Group 3); and mechanical cleaning with Merssage Fine for 10 s four times (Group 4). A glossmeter was used to measure surface gloss before and after mechanical cleaning, and a contact stylus profilometer was used to measure surface roughness (Ra). Results Polishing with prophylactic paste led to a significant reduction in surface gloss and increase in surface roughness among resin composite blocks, whereas the polishing-related change in surface gloss or roughness was smaller in Celtra DUO, a zirconia-reinforced lithium silicate block. Conclusions Changes in surface gloss and roughness due to polishing with a prophylactic paste containing large particles were not improved by subsequent polishing with a prophylactic paste containing fine particles. Key words:CAD/CAM, professional dental prophylaxis, prophylactic paste, surface gloss, surface roughness.

Polyisocyanurates have been successfully prepared by the thermal rearrangement of polycyanurates, which were obtained from 2,4-dichloro-6-methoxy-1,3,5-triazine and bisphenol monomers. The thermal rearrangement was carried out in the presence of a small amount of tetrabutylammonium bromide (TBAB) as a catalyst at 200 °C for 30 or 60 min in an argon atmosphere, and the degree of arrangement was greater than 95%. Transparent and amorphous polyisocyanurate films were obtained and showed a good thermal stability with a 5% weight loss temperature above 340 °C in nitrogen and the glass transition temperature above 210 °C. Films with a 10-µm thickness exhibited an excellent transparency above 90% at 400 nm. Furthermore, the thermal rearrangement of 2,6-bis(4-methoxyphenyl)-6-methoxy-1,3,5-triazine to 1,3-bis(4-methoxyphenyl)-5-methyl-1,3,5-triazinane-2,4,6-trione was investigated in detail. It was found that the complete thermal rearrangement was successfully accomplished in the presence of 2 wt % TBAB at 150 °C for 20 min in an argon atmosphere. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 692–698

The purpose of this study was to investigate the effect of type of rubber dam and application method on the moisture exclusion effect. The intraoral temperature and relative humidity were compared among various moisture exclusion appliances. Various dry field techniques were applied to 5 subjects and intraoral temperature and relative humidity measured 5 min after placing a digital hygro-thermometer in the mouth. The relative humidity was 100% in all subjects when moisture was excluded by means of cotton rolls alone. When only tooth 36 was exposed, relative humidity was significantly lower with latex, urethane, or 3-dimensional sheets than with cotton rolls alone, and was similar to the level of humidity in the room. When a local rubber dam was used, the relative humidity was significantly higher than the indoor humidity (p

Polycyanurates from 2,4-dichloro-6-methoxy-1,3,5-triazine with bisphenol A or 9,9-bis(4-hydroxyphenyl)fluorene were subjected to thermal treatment under argon to induce the thermal rearrangement of...

Trends among dental residents at Tokyo Dental College between 2006, at which time clinical residency became mandatory, and 2011 were analyzed and the following results obtained. Almost all the eligible students from our school participated in the orientation seminar on dental residency programs. Although the number varied slightly by year, approximately 70 to 150 students from other schools also participated in these orientation seminars. Almost all the students from our school and 60 to 80% of those from other schools participating in the orientation seminar each year applied to sit the dental residency entrance examination. The number of candidates was highest in 2006 (318) and lowest in 2010 (205) (average: 248), and the applicant-to-seat ratio for residency was 1.59. The examination pass rate was 59.02%. Approximately 10% of the students from other schools were admitted as dental residents.

This study evaluated the microtensile bond strength (μTBS) of 1-step self-etch adhesives (1-SEAs) and 2-step self-etch adhesives (2-SEAs) to pulp chamber dentin immediately after bleaching with 2 types of common bleaching techniques. Pulp chamber dentin of bovine teeth was bleached using 30% hydrogen peroxide (H2O2) solution with quartz-tungsten-halogen light-curing unit (Group 1) and 3.5% H2O2-containing titanium dioxide (TiO2) (Pyrenees®) activated with 405-nm violet diode laser for 15 min (Group 2). Unbleached specimens were placed in distilled water for 15 min and used as controls. After treatment, dentin was bonded with resin composite using 1-SEA or 2-SEA and stored in water at 37°C for 24 h. Each specimen was sectioned and trimmed to an hourglass-shape andμTBS was measured. Fractured specimens were examined under a scanning electron microscope to determine fracture modes. All specimens in Group 1 failed before proper bonding tests. In Group 2, theμTBS of 2-SEA was significantly greater (with no failed specimens) than 1-SEA (where 21 out of 36 failed). These results indicate that 2-SEA is a better adhesive system than 1-SEA on bleached dentin. Our results also demonstrated that application of H2O2significantly decreases bond strength of resin to dentin; however, in the case of nonvital tooth bleaching, Pyrenees® is a better alternative to the conventional 30% H2O2bleaching.

Background The authors evaluated the effects of three dry-field techniques (rubber dam, Isolite i2 [Isolite Systems, Santa Barbara, Calif.] and Coolex [APT, Osaka, Japan]) on intraoral temperature and relative humidity (RH), compared with the effects of a nonisolated control on intraoral temperature and RH. Methods The authors measured the room’s temperature and RH and then placed dry-field devices in five participants’ mouths and measured the intraoral temperature and RH for 20 minutes. They then removed the devices or turned off the vacuum system and measured intraoral temperature for an additional five minutes. Results The authors found no significant differences in either intraoral temperature or RH at any time during the measurement period in the isolated control group ( P > .05); the intraoral temperature was more than 30°C and RH was more than 95 percent. On the other hand, the use of dry-field techniques significantly reduced both intraoral temperature and RH when the rubber dam was in place or the vacuums were turned on ( P > .05). The intraoral temperature and RH gradually increased after the authors removed the rubber dam or turned off the vacuums. Conclusions The results of this study revealed that all three dry-field techniques could reduce both temperature and RH effectively. Clinical Implications Both Isolite i2 and Coolex could provide environments similar to the room conditions used during in vitro specimen preparation for investigating the mechanical properties of dental restorative materials.

Most manufacturers do not provide details about the photoinitiators contained in dental adhesives. Therefore, it is difficult to choose an optimal combination of dental adhesive and light-curing unit. The purpose of this study was therefore to investigate the spectral emission characteristics of several commercially available light-curing units and the spectral transmittance characteristics of contemporary dental adhesives. Spectral distributions of emitted lights were determined on a UV-vis-NIR spectrometer for three quartz-tungsten-halogen (QTH) light-curing units (Jetlite 3000, J. Morita; New Light VL-2, GC; D-Lux 2000, Dentrade) and three light-emitting diode (LED) light-curing units (Curenos, Shofu; G-Light Prima, GC; Bluephase, Ivoclar Vivadent). Spectral distributions of light transmittance in contemporary dental adhesives (Scotchbond Multi-Purpose, 3M ESPE; Adper Single Bond, 3M ESPE; One-Step, Bisco; AQ Bond Plus, Sun Medical; OptiBond All-in-One, Kerr; Clearfil S3 Bond, Kuraray Medical; G-Bond, GC; Tokuyama Bond Force, Tokuyama Dental; GBA 300 experimental, GC) were also determined. Each of the three QTH light-curing units had a wide emission range of 380-510 nm. A narrower emission range was observed in the LED light-curing units than in the QTH light-curing units. It was found that 2 LED light-curing units had dual peak wavelengths in both the blue and violet regions of the visible spectrum. There were some variations in light transmittance, and therefore the results suggested that some dental adhesives contain alternative photoinitiators besides camphorquinone. The selection of suitable light-curing units on the basis of the light absorption of dental adhesives and resin composites in dental clinics is of upmost importance.

The purpose of this study was to evaluate whether violet-laser diode (VLD) can be used as light-curing source. The ultimate (micro-)tensile strength (µTS) of three adhesives was determined when cured by VLD in comparison with curing by two different types of commercial LED light-curing units. One VLD (VLM 500) and two LED units (Curenos and G-Light Prima) were used to cure the adhesive resin of the two-step self-etch adhesives Clearfil SE Bond, Tokuso Mac Bond II, and FL- Bond II. A 0.6-mm thick acrylic mould was filled with adhesive resin and cured for 60 s. After 24-h water storage, specimens were trimmed into an hourglass shape with a width of 1.2 mm at the narrowest part, after which the µTS was determined (n = 10). In addition, the light transmittance of each adhesive was characterized using a UV-vis-NIR spectrometer. No significant difference in curing efficiency between VLD and LED were observed for both Tokuso Mac Bond II and FL-Bond II ( p> 0.05). For Clearfil SE Bond, the µTS of VLD-cured specimens was higher than that of the specimens cured by the LED Curenos unit ( p< 0.05). Spectrometry revealed that this marked difference must be attributed to a different light transmittance of Clearfil SE Bond for visible blue light versus for the lower area of UV and visible violet light. In conclusion, A GaN-based violet laser diode can be used as light-curing source to initiate polymerization of dental resins.

The aim of this study was to investigate whether atmospheric-pressure plasma (APP) or ultraviolet (UV) irradiation could alter the hydrophilicity of a computer-aided design/computer-aided manufacturing (CAD/CAM) glass ceramic surface, and thereby enhance the repair bond strength between the ceramic and a resin composite. Forty-eight leucite-reinforced glass ceramic discs were treated with 40% phosphoric acid and randomly assigned into one of six groups: Group 1, control, Group 2, treated with a mixture of Clearfil SE Bond primer (SEP) and Clearfil Porcelain Bond Activator (PBA), Group 3, subjected to APP irradiation for 10 s, Group 4, subjected to UV irradiation for 60 min, Group 5, APP irradiation followed by SEP/PBA, and Group 6, UV irradiation followed by SEP/PBA. After treatment, discs were bonded with resin composite using Clearfil SE Bond and stored in water at 37 &deg, C for 1 week. We then tested how these treatments affected the microtensile bond strength (&micro, TBS) and measured changes in the water contact angle (CA). Samples from Group 2 showed the highest &micro, TBS (44.3 &plusmn, 6.0 MPa) and CA (33.8 &plusmn, 2.3&deg, ), with no significant differences measured between Groups 1, 3, and 4 (p &lt, 0.05). Furthermore, the additional treatments of APP or UV before SEP/PBA had no effect (Group 5, p = 0.229) or a reduced effect (Group 6, p = 0.006), respectively, on &micro, TBS. Overall, APP or UV irradiation before SEP/PBA treatment did not enhance the repair bond strength.

This paper describes a novel method to reduce tool electrode wear in electrical discharge machining (EDM) by applying the relative sliding motion between electrodes. Experimentally, it was found that the cathode spot is more likely to slide on the electrode surface than the anode spot. Heat conduction analysis showed that material removal increases once with the moving speed of the heat source when the moving speed is low. After peaking at the maximum value, the material removal starts to drop, resulting in almost no material removal with the ultimate speed. In this study, the end of a tungsten anode rod was therefore machined by a copper cathode disc rotating at a high circumferential speed. The results showed that tool electrode wear ratio decreases with increasing rotational speed.