Orthodontic clear aligners have rapidly gained popularity. In cases of tooth extraction during clear aligner treatment, a bowing effect occurs, where the tooth tilts toward the extraction socket, in contrast to the simulation. Quantitative evaluation of orthodontic force is indispensable for elucidating the cause; however, many points regarding orthodontic force remain unclear. Therefore, we quantitatively evaluated the magnitude and distribution of the orthodontic force （as measured by the near-infrared birefringence and retardation） applied to the entire tooth and dentition by the clear aligner during canine tooth retraction using a two-dimensional birefringence measurement method. Additionally, we examined the effects of the amount of retraction of the canine teeth and the shape of the edge of the clear aligner on the orthodontic force. Eight clear aligner types were prepared by changing the amount of retraction of the canine teeth and the shape of the clear aligner margin, and the orthodontic forces applied by the clear aligners to the model were compared. A two-dimensional birefringence measurement system was used for measurement, and the orthodontic force was calculated from the generated optical retardation. A mechanical load was recognized in the canine tooth to which the orthodontic force was applied and in the other teeth. Additionally, differences in marginal morphology affected the magnitude and distribution of orthodontic force. Our results suggest that paying attention to the moving distance and the shape of the margin of the clear aligner is necessary when distally moving the canine teeth.

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Aligner-type orthodontic appliances （“aligners”）, which are more esthetically pleasing than fixed orthodontic appliances, have become widely used in recent years. However, several aspects remain unclear concerning the effects of tooth movement variables, including direction and distance on the orthodontic force. Therefore, we evaluated the magnitude and distribution of the orthodontic force exerted by aligners during arch expansion through two-dimensional birefringence measurement （e.g., near-infrared measurements of optical retardation）. Additionally, we investigated how differences in the number of teeth activated in parallel and the amount of activation affect the orthodontic force of the aligner. We prepared two types of aligner that either moved only one tooth （first molar） or three teeth （first premolar, second premolar, and first molar）, each with two activation types on one side, 0.25 versus 0.50mm, for a total of four types. We subsequently compared the orthodontic force applied by the aligner to the bite model. We used a two-dimensional birefringence evaluation system for measuring the optical retardation generated by birefringence due to orthodontic forces and calculated the mechanical energy from these data. The lateral expansion of only one tooth produced a greater load than the lateral expansion of three teeth when the same amount of activation was set. The orthodontic force for single-tooth expansion was reduced when the amount of activation was doubled. The reaction force on adjacent teeth was strong regardless of the number of expansion teeth. The results suggest that the number of tooth activations and the movement distance during dentition activation affect the magnitude and distribution of the orthodontic force.

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Clinical outcomes may differ from the simulation when the anterior teeth are retracted during aligner treatment. For example, the tooth axis of the anterior teeth may not be maintained, thereby resulting in excessive tipping on the lingual side and severe overbite and tooth root exposure. This study aimed to quantitatively evaluate the effects on orthodontic force magnitude and distribution of different movement methods when retracting anterior teeth during aligner treatment by performing two-dimensional birefringence evaluation （measurement using near-infrared birefringence and retardation）. Two types of aligners were prepared: one that tipped the anterior maxillary teeth by 0.63° to the lingual side and one that produced 0.25mm bodily movement of the tooth. Orthodontic forces exerted on a model by the aligners were compared, and the mechanical energy was calculated from the generated optical retardation using a two-dimensional birefringence measurement system （WPA-200-NIR）. Despite the insignificant difference observed in the amount of movement, significant differences were observed in orthodontic force magnitude and distribution when tipping and/or bodily movement occurred while retracting anterior teeth. Furthermore, loads were exerted in the other loci in addition to those in the anterior teeth. When retracting anterior teeth, orthodontic force magnitude and distribution varied on the basis of differences in the tooth axis tipping angle.

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The number of neurons in the brain increases over time, even in adults. This phenomenon, known as “neurogenesis”, is associated with neural stem cells present only in the dentate gyrus of the hippocampus. However, the frequency of neurogenesis is regulated by various factorsand mastication has been suggested as one such factor. In the present study, we examined the effects of varying the input of masticatory stimulation on neural stem cells using feed with different degrees of hardness. Male C57BL/5 mice were used in a comparative study. After weaning at 3weeks old, experimental mice were fed a soft or hard diet for 4 or 11weeks. To study the dynamic behavior of neural stem cells, the expression of two markers （nestin, a neural stem/progenitor cell marker; and doublecortin, a microtubule-associated protein） was quantitatively analyzed via immunostaining, whereas gene expression was analyzed by real-time polymerase chain reaction （RT-PCR）. Immunostaining-based quantification and gene expression analysis by RT-PCR revealed the decreased expression of markers in the hippocampus in the soft diet group compared to that in the hard diet group. Based on these results, the repression of neurogenesis by a soft diet was associated with changes in neural stem cells in the hippocampus and the frequency of neurogenesis.

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This study aimed to determine the accuracy of the evaluation system for LM1010 （HITACHI High-Tech Science, Tokyo, Japan） based on high-performance liquid chromatography coupled with ultraviolet-visible spectroscopy for therapeutic drug monitoring of the active metabolite mycophenolic acid （MPA） of mycophenolate mofetil （MMF） following renal transplantation and immunosuppressant therapy. We included six patients （including 4 males and 2 females; mean age, 49±13 years） who provided written informed consent. Blood sampling was performed at 0, 1, 2, 3, 4, 6, and 9hr after the administration of 750mg of MMF. The resulting measurements using the LM1010 method and the outsourcing method, high-performance liquid chromatography-mass spectrometry （HPLC-MS/MS）, were compared. The serum concentration of MPA was not significantly different between the LM1010 and HPLC-MS/MS methods for the 42 samples from six patients （4.2±3.5 vs. 4.5±4.1µg/ml）. MPA measurements were correlated with LM1010 and HPLC-MS/MS （r²＝0.9459）. No significant differences in pharmacokinetic parameters, that is, peak serum concentration （C_max） （8.6±4.7 vs. 8.9±5.7µg/ml）, time to peak serum concentration （T_max） （2.4±1.1 vs. 2.4±1.1hr）, estimated serum concentration 12hr after oral administration （C₁₂） （1.3±1.6 vs. 1.4±1.8µg/ml）, and area under the serum concentration-time curve 0-12hr after oral administration （AUC_0-12） （40.6±28.2 vs. 36.9±34.1µg/ml）, were observed between LM1010 and HPLC-MS/MS. In clinical settings, LM1010 can help determine the MPA concentration in patients treated with MMF after renal transplantation.

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