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Needlestick and sharps injuries (NSIs) are serious problems for dental health care workers (DHCWs) because they are at risk for occupational blood-borne infections. In this study, risk factors for NSIs in DHCWs at Tohoku University Hospital (TUH) in Japan over 19 years were analysed.NSI data of DHCWs at TUH from April 2002 to March 2020 were collected from the Exposure Prevention Information Network (EPINet) and statistically analysed.A total of 195 NSIs occurred during the 19-year study period. Approximately 58.5% of NSIs occurred in DHCWs with less than 5 years of experience. Injection needles were the most frequent cause of NSIs (19.0%) followed by suture needles (13.3%) and ultrasonic scaler chips (12.8%). Needle injuries occurred mainly on the left hand, whereas ultrasonic scaler chip and bur injuries occurred on the right hand and other body parts whilst DHCWs were placing the instruments back on the dental unit hanging holder without removing the sharps. NSIs from other instruments primarily occurred on both hands and foot insteps during cleanup. No case of occupational blood-borne infection caused by NSIs was observed during the study period at TUH.NSIs occurred in DHCWs with less experience, and there were associations between the instruments, timing of use, and NSI site. EPINet was considered a valuable tool for monitoring NSIs in order to develop future strategies for minimising NSIs.

Single phase specimens of hollandite-type MnO2, TiO2, and KxTi1 − yMnyO2, were synthesized, and their electrochemical properties and crystal structures were investigated. The chemically prelithiated MnO2 and sufficiently K+-extracted TiO2 specimens exhibited good charge–discharge properties. The initial Li insertion capacities were about 160 mAh/g for TiO2 and about 230 mAh/g for MnO2. In contrast, the partially K+-extracted solid solution, K0.055Ti0.75Mn0.25O2, showed a poor charge–discharge property. The small amount of residual K+ ions in the tunnel structure affected significantly the charge–discharge property. Electron density distribution images obtained from X-ray powder diffraction data elucidated that stabilizing O atoms locate at the tunnel space of lithiated MnO2 but the tunnel space of TiO2 was essentially empty.

The patient was a 22-year-old Japanese woman who complained of a gummy smile. She had several other orthodontic problems, including crowding of the maxillary anterior teeth, retroclination of the maxillary central incisors, excessive maxillary incisor display, a deep overbite, Class II dental relationships, a Class II profile, and a long face. Two options for the correction of these problems were proposed. The first option was to extract the maxillary first premolars to correct the Class II relationship and implant a miniscrew to correct the gingival display; the second option was to place 2 miniplates for distalization of the maxillary molars and a miniscrew to correct the gingival smile without premolar extractions. The patient chose the second option. After placing a preadjusted bracketed system, 2 miniplates were placed in the zygomatic buttresses bilaterally with monocortical screws, and 1 miniscrew was fixed between the root apices of the maxillary central incisors. Distalization and intrusion of the maxillary molars and intrusion of the maxillary incisors were simultaneously started with those temporary skeletal anchorage devices functioning as absolute orthodontic anchors. The total treatment period was approximately 22 months. Her orthodontic problems were corrected. According to the cephalometric evaluation, the entire maxillary dentition was significantly distalized, and her maxillary incisors were successfully intruded, with the mandible showing a slight counterclockwise rotation. Thanks to the temporary anchorage devices combined with miniplates and a miniscrew, we were able to predictably achieve her treatment goals without premolar extractions, orthognathic surgery, and the need for patient compliance.

Single-phase specimens of α -MnO 2 (hollandite-type) and β -MnO 2 (rutile-type) were synthesized by the acid digestion of Mn 2 O 3 under reflux conditions. The type of polymorph of MnO 2 products was strongly dependent on the reaction temperature, type of acid used, and its concentration. The pH titration curve of α -MnO 2 displayed a monobasic acid behavior toward Li + , but β -MnO 2 showed a poor ion-exchange property. In contrast, both α -MnO 2 and β -MnO 2 acted as a rechargeable active material in a liquid organic electrolyte lithium cell. The initial discharge capacities of both electrodes exceeded 200 mAh/g (cut-off voltage: 2 V). After discharge–charge repetition, the α -MnO 2 structure was still retained without structure collapse, although the β -MnO 2 structure was destroyed. These findings show that Li + ions can be inserted only into the hollandite-type tunnels in α -MnO 2 and cannot diffuse the rutile-type linkages in α -MnO 2 as well as those in β -MnO 2 without structure collapse.

Accelerating the speed of orthodontic tooth movement should contribute to the shortening of the treatment period. This would be beneficial because long treatment times are a negative aspect of orthodontic treatment. In this study, we evaluated the effects of mechanical stimulation by resonance vibration on tooth movement, and we showed the cellular and molecular mechanisms of periodontal ligament responses.The maxillary first molars of 6-week-old male Wistar rats were moved to the buccal side by using an expansive spring for 21 days (n = 6, control group), and the amount of tooth movement was measured. Additional vibrational stimulation (60 Hz, 1.0 m/s(2)) was applied to the first molars by using a loading vibration system for 8 minutes on days 0, 7, and 14 during orthodontic tooth movement (n = 6, experimental group). The animals were killed under anesthesia, and each maxilla was dissected. The specimens were fixed, decalcified, and embedded in paraffin. Sections were used for immunohistochemical analysis of receptor activator of NF kappa B ligand (RANKL) expression. The number of osteoclasts in the alveolar bone was counted by using TRAP staining, and the amount of root resorption was measured in sections stained with hematoxylin and eosin.The average resonance frequency of the maxillary first molar was 61.02 +/- 8.38 Hz. Tooth movement in the experimental group was significantly greater than in the control group (P.05). Enhanced RANKL expression was observed at fibroblasts and osteoclasts in the periodontal ligament of the experimental group on day 3. The number of osteoclasts in the experimental group was significantly increased over the control group on day 8 (P.05). Histologically, there were no pathological findings in either group or significant differences in the amount of root resorption between the 2 groups.The application of resonance vibration might accelerate orthodontic tooth movement via enhanced RANKL expression in the periodontal ligament without additional damage to periodontal tissues such as root resorption.

Oxide films were formed on titanium by means of microarc oxidation (MAO) using a direct current power supply. The oxide films containing Ca and P were obtained in an electrolyte containing β-glycerophosphate sodium salt pentahydrate (β-GP) and calcium acetate (CA). The surfaces of the oxide films were rough and porous, and the concentration of Ca and P were 7.3 mol% and 6.4 mol%, respectively, when MAO was performed in an electrolyte containing 0.04 M β-GP and 0.10 M CA at 200 A/m 2 current density and 430 V final voltage. The oxide film consists of anatase, rutile and an amorphous phase. After hydrothermal treatment at 190 °C, the hydroxyapatite crystals were precipitated on the oxide film surfaces. The amount of hydroxyapatite crystals increased by increasing the hydrothermal treatment time and the Ca/P ratio in the oxide film.

Microarc oxidation (MAO) was performed on Ti–6Al–4V in electrolytes containing calcium glycerphosphate (Ca-GP) and calcium acetate (CA) using a regulated direct current power supply. It was found that the MAO method was suitable for Ti–6Al–4V to form a ceramic coating in electrolytes of Ca-GP and CA, and the oxide films displayed a porous and rough structure on the surface of films. The film with a Ca/P ratio equivalent to hydroxyapatite was obtained when final voltage and current density were 350 V and 200 A/m2 in the electrolyte containing 0.06 M calcium glycerphosphate (Ca-GP) and 0.25 M calcium acetate (CA). After hydrothermal treatment, the hydroxyapatite was precipitated on the surface of the film obtained by MAO and the hydroxyapatite thickness was about 4 μm. The films were investigated by means of electron probe micro-analysis, atomic force microscopy, X-ray diffractometry and scanning electron microcopy before and after hydrothermal treatment.

Microarc oxidation (MAO) was performed on titanium in an electrolyte containing calcium glycerphosphate (Ca-GP) and calcium acetate (CA) using a direct current power supply. It was found that the MAO method is suitable forming a ceramic coating containing Ca and P using titanium, and that films display a porous and rough structure on their surface. Samples with a Ca/P ratio of 1.71 were hydrothermally treated in water solution whose pH was adjusted to 7.0-11.0 by adding NaOH at 190 degrees C for 10 h in an autoclave. Hydroxyapatite crystals were precipitated on the film surface after the hydrothermal treatment, and the amount of hydroxyapatite precipitated increased with increasing pH of water solution. The oxide film composition was semiquantitatively analyzed with an electron probe microanalyzer. The microstructures on the sample surfaces were observed by scanning electron microscopy before and after the hydrothermal treatment. The topography of the oxide film was imaged with an atomic force microscope. Its cross section was observed by scanning electron microscopy after being coated with a thin Au film. The surface structures of the films were analyzed by X-ray diffraction.

The purpose of this study was to examine the effect of 4-amino-1-hydroxybutylidene-1, 1-bisphosphonate (AHBuBP), a potent blocker of bone resorption, on orthodontic tooth movements in rats. In the first experiment, the right and left upper first molars were moved buccally for 3 weeks with a uniform standardized expansion spring under systemic administration of AHBuBP every other day. The total tooth movement during the 3-week experimental period was 40% of that in the control at a dose of 0.5 mg P/kg. In the second experiment, the right and left upper first molars were first moved buccally for 3 weeks without AHBuBP. The spring was then removed and administration of AHBuBP was initiated. The total relapse movement during the 3-week experimental period was 50% of that in the control at a dose of 0.5 mg P/kg. Results of the first and second experiments were both dose dependent. Histologic examination showed that in the experimental animals fewer osteoclasts appeared on the alveolar bone surface, and both bone resorption and root resorption were inhibited. Inhibition of tooth movement was also observed when AHBuBP was applied topically. These results suggest that AHBuBP could be useful in enhancing anchorage or retaining teeth in orthodontic treatment.

The aim of this study is to evaluate the performance of a newly developed Ni-free SMA wire as an orthodontic wire by comparing with a Ni–Ti wire. A Ti–Nb–Al superelastic wire or an orthodontic superelastic wire (Ni–Ti wire) was set in the mouth of male Wistar-strain rats, and orthodontic palatal movement of maxillary first molars was performed with an initial load of 15 gf. The amount of tooth movement was measured and periodontal structures were observed using microfocus X-ray CT radiographs. There was no significant difference in the amount of movement between the Ti–Nb–Al group and the Ni–Ti group. Microfocus X-ray CT observation revealed no morphological differences between the two groups. Our results indicate that the Ti–Nb–Al wire can be a comparable orthodontic wire to the Ni–Ti wire.

The aim of this study was to confirm the usefulness of magnets for orthodontic tooth movements. Computer simulation was performed to design magnets, especially for this new animal model. The flux density and attractive force of samarium–cobalt (Sm–Co) magnet and neodymium–iron–boron (Nd–Fe–B) magnet were examined. The magnet or titanium was bonded on the rat maxillary first molars. The initial distance between magnets/titanium was 1.0 mm (experimental group I/control group I, Exp. I/ Cont. I) or 1.5 mm (experimental group II/control group II, Exp. II/Cont. II). The amount of tooth movement was measured and periodontal structures were observed using microfocus X-ray CT radiographs. The distance between magnets decreased in both experimental groups. Tooth movement in Exp. II was slower than Exp. I. Horizontal sections of microfocus CT radiographs showed narrow periodontal space without root resorption on the pressure side in both experimental groups. Attractive force of the newly designed magnets caused effective tooth movement without any pathological changes in rats.

The solid-state reaction of strontium sulfate with anatase and rutile was examined by isothermal and non-isothermal TGA/DTA and X-ray diffraction. The endothermic peak due to the reversible phase transition of SrSO 4 was observed by DTA in the vicinity of the endothermic peak due to the reaction. The product was only SrTiO 3 in all cases. The reaction mechanism was described by the Jander model. The rate constant for anatase was about twice as large as that for rutile. The relation between In k j and T −1 for anatase and rutile was discontinuous being linear either side of the phase transition temperature of SrSO 4 . The rate constant just above the transition temperature was enhanced 1.5 times with respect to that just below the temperature. The activation energy for the reaction of strontium sulfate with rutile was 354 and 435 kJ mol −1 in the higher and lower temperature regions respectively. In the reaction with anatase, the phase transition of anatase to rutile was also observed in about 30% of the fraction reacted at any temperature, and the rate constant was scattered from the In k j vs. T −1 curve, especially at high temperatures.