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This study aimed to create a biomaterial from titanium dioxide (TiO2), which has been known to have photocatalytic and bone formation promoting effects. I expected that anatase titanium dioxide-based implants could promote bone augmentation and induce bone formation. Powdery anatase TiO2 was compression molded and sintered at 700, 800, 900, and 1000 °C to prepare sintered compact samples. X-ray diffraction and scanning electron microscopy were used to observe the surface of these samples. Furthermore, mouse osteoblast-like cells (MC3T3-E1 cell line) were seeded on the samples sintered at different temperatures, and cell proliferation was observed to evaluate the cell proliferation of the samples. The sample sintered at 700 °C was composed of anatase TiO2. The samples sintered at 800 °C and 900 °C were confirmed to consist of a mixture of anatase and rutile TiO2 crystalline phases. Moreover, the sample sintered at 700 and 800 °C, which contained anatase TiO2, showed remarkable photocatalytic activity. Those samples sintered at 1000 °C were transformed to the rutile TiO2. The cell proliferation after 7–14-days culturing revealed that cells cultured on the 700 °C sample decreased in number immediately after initiation of culturing. The cells cultured on TiO2 sintered at 900 °C markedly proliferated over time with an increase in the alkaline phosphatase activity, showing good MC3T3-E1 cell compatibility of the samples. The sample sintered at 1000 °C, which is rutile TiO2, showed the highest increase.

The aim of this study was to clarify the effect of attachment on tooth movement produced by a plastic aligner. Closing of a diastema, in which the maxillary right and left central incisors moved bodily, was simulated using a finite element method. Long-term orthodontic movements of the maxillary dentition were simulated by accumulating the initial displacement of teeth produced by elastic deformation of the periodontal ligament. The incisor tipped and rotated just after placement of the aligner irrespective of the attachment. After a sufficiently long time, the incisor was upright and moved bodily in the aligner with attachment, but the incisor remained tipped in the aligner without attachment. It was demonstrated that the attachment was effective for achieving bodily movement.

The mechanism in the formation of periodontal polyp has been established in several histological studies but details on cell differentiation and/or proliferation have not been elucidated. In the present study, we established a convenient and possible experimental system using ddY mice. Briefly, pentobarbital sodium (Somnopentyl) was injected into the abdominal cavity of the mouse followed by access cavity preparation on maxillary first molar using low speed ½ round bur (Merufa Inc), exposing the pulp and then allowed to perforate the floor of the pulp chamber. Observation was done over time until 6 months using micro CT (m_CT) image photography. Results with transmission image using m_CT showed theexpansion in the width of the periodontal ligament in the furcation area. The lesion was excised as one mass and examined histopathologically. The granulation tissue was covered with stratified squamous epithelium. The present experimental technique has been confirmed to be effective in analyzing the formation of periodontal polyp induced by mechanical perforation.

Although studies on the formation of apical periodontitis have somehow been carried out but detailed cellular dynamics remain unclear. We recently established an experiment that could easily be performed using ddY mice. First, under general anesthesia using isoflurane inhalation, the coronal portion of the maxillary first molar was penetrated using a round bur and drill with water irrigation causing pulp exposure until the root apex. Micro computed tomography (R_mCT) was taken over time during observation. Four weeks later, R_mCT confirmed the presence of a radiolucent image at the apex of the tooth, which was then removed for histological examination. The results showed that granulation tissue with fibrosis had gradually formed at the periphery of the abscess. The present method confirmed the effectiveness of the experimental mode to exmine the formation of chronic inflammatory lesions at the root apex.

The aim of the present study is to increase the knowledge about the molecular mobility of cefditoren pivoxil (CDTR-PI) on the granules surface by studying the glass transition temperature (Tg) of the drug using inverse gas chromatography (IGC), and to clarify the inhomogeneity of the granule resulting in the physical stability of them. The Tg of the granulated amorphous CDTR-PI and the granulated CDTR-PI with polymers were measured by inverse gas chromatography (IGC) and differential scanning calorimetry (DSC). There was no difference among samples in the Tg measured by DSC. However, the Tg measured by IGC were different among samples; the value of CDTR-PI with hydroxypropylcellulose (HPC-L) was lower than the others, and showed a tendency similar to spray-dried samples. It was suggested that IGC measured the surface transition temperatures of granules that was impossible to measure by DSC. By comparison with the influence of the Tg on the surface and the whole granule on the crystallization rates of them, the surface Tg strongly affected the physicochemical stability of granules compared to those of the whole.

The evaluation of the physicochemical stability of granules of amorphous cefditoren pivoxil (CDTR-PI), alone or with polymers, demonstrated that granulated amorphous CDTR-PI with hydroxypropyl methylcellulose was the most stable. We measured glass transition temperature by differential scanning calorimetry (DSC). The molecular mobility of the whole granules did not change, and it was not consistent with the results of the evaluation of physicochemical stability. Peak shifts were observed in IR spectra of amorphous CDTR-PI with polymers after granulation, and the shifts were similar to those observed for spray-dried samples. Furthermore, the shifts were not observed after the granules were ground. Acid–base parameters, which were also measured by inverse gas chromatography (IGC), changed after granulation. These results suggested that on the surface of the granules, CDTR-PI and the polymers would be mixed monomolecularly, as in the spray-dried samples. The changes in the molecular state of a drug when mixed monomolecularly with a polymer on the surface of granules were successfully confirmed by IGC and IR.