Magnetic resonance imaging（MRI）has contrast resolution and is frequently used to soft tissue diseases and diagnose bone marrow. The efficacy of MRI in the evaluation of various disease in nerve and bone marrow tissue has been reported in previous studies. However, to our knowledge, only few studies have assessed the mandibular canal（MC）affected by osteomyelitis using MRI. The purpose of this study was to evaluate the MC on inflammatory condition using MRI. One hundred thirty patients with osteomyelitis （50 men, 80 women; mean age, 55.7 years; age range, 20–89 years）who visited our hos pital between April 2013 and March 2020. Osteomyelitis was diagnosed based on the clinical symptoms and typical clinical imaging findings. The Wilcoxon signed-rank test was used to compare the apparent diffusion coefficient（ADC）value of the MC on the affected by osteomyelitis and non-affected side. This test was calculated using the ADC value of the MC as the criterion variable and disease status as explanatory variable. Statistical significance was set at P<0.05. The median ADC value of the MC on the affected side was 1.34×10^-3 mm²/s and that of the MC on the non-affected side was 1.12×10^-3 mm²/s. The median ADC value of the MCs affected side were higher than those of the non-affected side（P<0.01）. The ADC values of the MC was able to distinguish between affected side and non-affected side. These results suggested that the MRI might serve as a noninvasive method to evaluation the presence of MC on inflammatory condition.

Pleomorphic adenoma is a common salivary gland tumor, representing about two-thirds of cases. Surgical excision is the primary treatment, usually leading to a good prognosis. However, there have been occasional reports of recurrence and malignant transformation. These tumors typically have a capsule, but it can be incomplete or invaded. This makes it crucial to examine the relationship between peripheral tumor tissue and cells within the capsule during histopathological examination. A study at Nihon University School of Dentistry Hospital included 44 cases of palatal pleomorphic adenomas, chosen from 50 based on capsule presence and the absence of satellite nodules. Immunohistochemical stains, SOX 10 and EGFR, were used. HE-stained specimens were classified into four groups following Seifert’s classification, with Subtype 1 as ‘classic type,’ Subtype 2 as ‘stroma-rich type,’ and Subtypes 3 and 4 as ‘cellular-rich type.’SOX-10-positive cell ratios varied significantly near the capsule among these groups. EGFR immunoreactive scores were highest in the cellular type, indicating greater biological activity. The study highlights a strong correlation between Seifert’s classification and the ratio of tumor-forming myoepithelial cells near the capsule. Cellular type demonstrated the highest IRS, suggesting heightened biological activity, which is supported by SOX-10 and EGFR staining patterns. In summary, this study suggests a link between Seifert’s classification and biological activity in minor salivary gland pleomorphic adenomas. Cellular type exhibited a potential for higher biological activity, based on staining patterns and IRS.

The purpose of present study was to examine whether decreased temporal muscular activity after the removal of the temporalis muscle is related to the number of neural stem cells in hippocampal dentate gyrus in rats. Six rats in control group were incised and sutured in the temporal region, whereas each of six rats in unilateral- and bilateral-cut groups underwent removal of the right and both temporalis muscles, respectively, and were sutured. At 27 weeks postnatally, the numbers of Bromodeoxyuridine labelled cells in unilateral-cut and bilateral-cut groups were considerably lower than that in control group. The ratios of neurons to Bromodeoxyuridine labelled cells in unilateral-cut and bilateral-cut groups were considerably lower than that in control group. The findings of this study suggest that decreased temporal muscle activity is associated with fewer neural stem cells in hippocampal dentate gyrus.

Oral biofilms contribute to oral infectious diseases such as dental caries and periodontal disease. Actinomyces oris, an initial attachment colonizer, uses fimbriae（FimA, FimP, and FimQ）presented on the surface layer of the bacteria for biofilm formation. Streptococcus mutans, a cariogenic bacteria, produces membrane vesicles（MVs）with insoluble glucan synthases（GtfB and GtfC）and extracellular DNA（eDNA）. These MVs promote biofilm formation. However, few reports are available on the relationship between S. mutans-produced MVs and A. oris. Herein, the authors investigated the effect of S. mutans-produced MVs on the initial attachment and colonization（INAC）, and biofilm formation of A. oris. MVs at a final concentration of 3.125 µg/mL promoted the INAC formation of WT, ΔfimA, ΔfimP, and ΔfimQ of A. oris. However, MVs from S. mutans ΔgtfBC, lacking insoluble glucan synthase, did not induce the INAC formation in A. oris wild type and mutants. Deoxyribonuclease inhibited INAC formation of A. oris WT and ΔfimA produced by MVs. This study indicated that S. mutans-produced MVs induced fimbriae-independent INAC formation of A. oris via insoluble glucan synthase. The formation of insoluble glucan-dependent INAC in A. oris via S. mutans-produced MVs may result from the interaction between A. oris type 1 fimbriae with eDNA from MVs, potentially contributing to the stabilization of the INAC structure.

This study investigated changes in chewing satisfaction from old to new dentures, exploring how perceived masticatory difficulty with the old denture influenced food intake with the new dentures. Additionally, factors influencing overall masticatory satisfaction with the new dentures were examined. Consecutive sampling involved edentulous individuals seeking replacements for both maxillary and mandibular complete dentures. A total of 103 edentulous individuals（49 males, 54 females; age range: 39-87 years; mean age: 71.6±8.6 years）participated. At the baseline visit, patients provided general satisfaction ratings for their dentures in terms of subjective mastication. A 12- item questionnaire, using a 100mm visual analog scale（VAS）, assessed their ability to chew specific foods（tofu, fish cake, bean sprouts, cubic rice crackers, rice crackers, and squid jerky）with existing maxillary and mandibular dentures. The study revealed a significant increase in VAS for overall masticatory satisfaction and the intake of six Japanese foods with diverse textures. Notably, perceived masticatory difficulty with previous dentures exerted a substantial impact on subsequent food intake with new dentures. Factors influencing perceived mastication with the new dentures included crunchy foods（cubic rice crackers and rice crackers）and elastic foods（fish cake）. These findings highlight the considerable influence of old denture-related masticatory difficulty on overall masticatory satisfaction and subsequent food intake with new dentures. The study suggests valuable insights for treatment planning and denture design, emphasizing the necessity of considering these factors when fabricating new dentures and providing guidance to patients post-insertion.

This study examined changes in masticatory function indices, maximum occlusal force, masticatory performance, and masticatory score before and after removable prosthesis treatment, taking into account the prosthetic difficulty level, which assesses factors such as the shape of the residual ridge and properties of the mucous membrane. Participants（n=40, mean age 75.0±6.8 years）seeking prosthetic treatment were evaluated. Significant improvements in maximum occlusal force were observed in Classifications I and III, while masticatory performance improved significantly in Classification III. Multiple regression analysis indicated that post-treatment maximum occlusal force was significantly influenced by pre-treatment maximum occlusal force（p = 0.01）, with marginal significance in the number of remaining teeth（p = 0.06）（adjusted R² = 0.38）. Factors significantly associated with post-treatment masticatory performance included pre-treatment masticatory performance（p = 0.03）（adjusted R² = 0.27）. Additionally, the post-treatment masticatory score was significantly associated with the pre-treatment masticatory score（p < 0.00）（adjusted R² = 0.55）. The findings suggest challenges in improving masticatory indices, particularly at Level IV, the most difficult index. Post-treatment maximum occlusal force, masticatory performance, and masticatory score significantly correlate with the pre-treatment status of each index. These results propose the utility of prosthetic difficulty level and masticatory indice（msasticatory performance, maximum occlusal force, and masticatory score）as predictive indicators for patients seeking denture treatment.

To date, significant research has been conducted on biological apatite, the composition of which deviates considerably from that of hydroxyapatit（eCa（PO_{l0 4}）（₆ OH）₂）. Our previous studies have shown individual differences in the composition of biological apatite in human enamel and diversity in enamel. Furthermore, heating amplified the variability of the components. A study on soft drink demineralization has found that Sprite^® has the highest enamel solubility among many soft drinks. Fourier transform infrared spectrophotometers are often used to analyze the composition of materials. This study comprehensively investigated the mechanism of Sprite^® induced demineralization. Human enamel demineralized with Sprite^® and heated was compared with that heated after resting in a container moistened with saline solution. The samples were then analyzed by micro-Fourier transform infrared spectroscopy（micro-FTIR）. The results showed that the peak values for carbonate were consistent with those of common biological apatite crystals. The peak values for phosphate were 471 to 594 cm^-1 for the PO₄³ν^-₂ absorption band, 555 to 675 cm^-1 for the PO₄³ν^- ₄ absorption band, 960 to 1,192 cm^-1 for the PO₄³ν^- ₁ absorption band, and 1,003 to 1,227 cm^-1 for the PO₄³ν^- ₃ absorption band. Additionally, the peak intensity of the carbonate peak decreased in all samples after demineralization, whereas the phosphate peak partially increased in intensity and shifted significantly to the left. Furthermore, decreased intensity of the carbonate peak was observed in all samples in the experimental group, suggesting that carbonate was leaking into the Sprite^® soaking solution. Other papers have not found such significant changes in phosphate in caries or in demineralization reactions with other demineralizing solutions. The difference may be because Sprite^® was used for demineralization. Future studies should compare the components of the Sprite^® soaking solution before and after demineralization to clarify the kinds of chemical reactions that have occurred.