To clarify the mechanism underlying the regulation of osteoclast differentiation and activation in giant cell tumor of bone, we investigated the expression of osteoclast-related markers in osteoclasts, neoplastic cells, and osteoclast precursors comprising giant cell tumor of bone using immunohistochemical analysis, and analyzed the distribution of receptor activator of nuclear factor κ-B ligand (RANKL)-expressing cells. We performed serial staining of sections using antibodies against osteoclast-related markers including RANKL, CD68, CD11b, c-Fms, RANK, and cathepsin K and analyzed the presence of the G34W mutation of H3F3A in giant cell tumor of bone. Mononuclear cells were CD11b⁺, CD68⁺, RANK⁺, and c-Fms⁺. In contrast, most multinucleate cells were CD11b^–, CD68⁺, RANK⁺, and c-Fms⁺. RANKL was expressed in mononuclear cells and some multinucleate cells. Conversely, G34W was detected in mononuclear cells. RANKL⁺ mononuclear cells were also G34W⁺. RANKL expression was unevenly distributed in giant cell tumor of bone. RANKL⁺ cells were frequently localized along blood-containing cavity-like spaces. In areas with a high percentage of RANKL⁺ mononuclear cells, large numbers of osteoclasts were observed. In addition, the distribution of multinucleate cells (>100 µm in diameter) correlated with the distribution of RANKL⁺ cells. The distribution of RANKL⁺ mononuclear cells is uneven in giant cell tumor of bone and may have some effect on the localization of multinucleate cells. The distribution of mononuclear cells harboring the G34W mutation was identical to that of RANKL⁺ mononuclear cells.

We examined the age-dependent effects of the alendronate sodium hydrate (alendronate) on the ultrastructure of the golden hamster parathyroid gland (PTG). At 1 year of age, the percent area of Golgi apparatus and lysosomes in alendronate-treated hamster PTG was significantly increased in comparison to control hamsters, while at 2 years of age, the percent area of lipid droplets was significantly decreased relative to control hamsters. These findings suggest that alendronate promotes the synthesis of hamster parathyroid hormone at 1 year but not 2 years of age. These results indicate that the sensitivity of PTG to alendronate is age-dependent.

The in vitro and in vivo degradation behavior and osteogenic ability of new hydrothermal hydroxyapatites (HAs) were investigated. Two different HA granules with short and long-rod HA crystals (SRHA and LRHA, respectively) were hydrothermally synthesized. A low pH immersion test was performed to observe morphological degradation features. At 2 days, HA in a low pH immersion fluid revealed pitfall-like degradations on the surface. Both HA granules were implanted in rat calvaria bone defects. The biodegradable behavior and effects of new bone formation were histologically and radiographically investigated. At 4 and 24 weeks after surgery, defect areas were filled with implanted HAs and newly formed bone. No differences in boundary area shapes between SRHA and LRHA were found. The area of LRHA degradation was greater compared with SRHA (p < 0.05). At 24 weeks, implanted HA granules showed inward incursion of fibrous tissue and tissue fluid. Accordingly, in vivo hydrothermal HA indicated good osteogenesis and progress.

The goal of hard tissue reconstruction in the oral and maxillofacial field is suitable oral function in elderly patients. Recently, some studies have reported an association between cardiovascular diseases and oral function. However, these have not been supported by extensive evidence and further collection of data is needed. This study included 108 residents of Takatsuki City who were 65 years of age or older. Oral environment and function (number of teeth, maximum occlusal force, gummy score, and chewing time), vascular functions (brachial-ankle pulse wave velocity, baPWV; and ankle brachial pressure index, ABI) were measured. Negative correlations were observed between the number of teeth and baPWV, maximum occlusal force and baPWV, and gummy score and baPWV. A negative correlation was observed between chewing time and rtABI. Multiple linear regression analysis showed that maximum occlusal force had significant negative associations with baPWV (standardized partial regression coefficient (β) = -0.251, p<0.05) after controlling for age. The present study suggested some degree of association between oral function and cardiovascular diseases. A decline in masticatory efficiency may limit the type of foods that can be ingested, leading to changes in dietary habits and associated imbalances in nutritional intake. Furthermore, progression of periodontal disease caused by reduced salivary secretion may influence vascular sclerosis, thus supporting the development of cardiovascular diseases. Further research is needed to determine the causal relationship.

The goal of hard tissue reconstruction in the oral and maxillofacial field is good oral function. However, research into oral function remains inadequate and methods for evaluating oral function have yet to be established. In this study, we report the relationship between oral function and occlusal bite force in the elderly. This study included 108 residents of Takatsuki City aged 60 years or older. Oral condition was assessed by measuring tooth loss and periodontal condition, and oral function was assessed based on masticatory performance indicators. Mean age was 75.5±4.8 years. As indicators of occlusal function, the means of maximum occlusal force, gummy jelly score (masticatory performance score) and time required for 30 chews were 313.5±234.8 N, 4.0 and 28.5±10.0 s, respectively. As indicators of oral function, the means of tongue pressure, salivary flow rate and lip pressure were 26.3±8.9 kPa, 1.5±0.93 g/min and 12.7±7.1 N, respectively. In this study, we report mean values for oral function in healthy elderly subjects. In the future, it will be necessary to clarify standard values for residents with various diseases.

Tooth loss is one of the most important factors in preventing the development of dementia in aging societies. Although numerous studies focusing on this relationship have been conducted, few studies have investigated the relationship between oral function and the development of dementia. Therefore, in the present study, we examined the relationship between oral and cognitive functions in the elderly population. This study included 108 residents of Takatsuki City aged 65 years or older. We analyzed jaw function based on each individual’s tooth loss and periodontal condition. In addition, we used the Japanese version of the Mini-Mental State Examination and Trail Making Test (TMT) A/B to assess subjects’ cognitive function. Spearman’s rank-order correlation coefficient was used in the statistical analysis. There was a significant negative correlation between the number of teeth, maximum occlusal force, and scores on the TMT A and B times. There was also a significant negative correlation between the tongue pressure and the TMT A time. The present study’s results suggest that dental and hard tissues should be actively reconstructed in the elderly population to help prevent the development of dementia.

Biphasic calcium phosphate (BCP) cement, consisting of an α-tricalcium phosphate-tetracalcium phosphate as the only solid phase and a calcium phosphate solution (Ca-P soln) as the liquid phase, was formerly reported. The BCP cement was easy to prepare, and was expected to show desired handling properties and to form hydroxyapatite (HA) for clinical applications. The objective of the study was to evaluate physical properties and HA formation of the BCP cement. The solid phase of the cement was a BCP (Ca/P of 1.8) prepared in a furnace and ground to a median size of 9.96µm. The liquid phase of the BCP cement consisted of an acidic Ca-P soln, which was produced by mixing phosphoric acid with calcium carbonate (CaCO₃) and diluted 3.0-fold, 3.5-fold, 4.0-fold with H₂O. Additionally, trisodium citrate anhydrous and polyvinylpyrrolidone were included as a water reducing agent and washout resistance enhancer, respectively. Cement powder and liquid were mixed (P/L=3.0) to produce samples for setting time, diametral tensile strength (DTS) and compressive strength (CS) measurements. X-ray powder diffraction (XRD) analyses and microscopic observations by FE-SEM and atomic force microscope (AFM) were also performed to identify HA conversion in set samples with time chronologically. BCP cement showed good washout resistance when immersed in water. The setting times (n=5) were 3.0-fold: 5.24±0.01min, 3.5-fold: 7.39±0.01min and 4.0-fold: 9.06±0.01min at 25±1°C. Differences were apparently existed between each sample (p<0.05). One-day wet DTS (n=5) values were 3.0-fold: 7.07±0.51MPa, 3.5-fold: 5.98±0.91MPa and 4.0-fold: 5.07±0.51MPa and CS (n=5) values were 3.0-fold: 46.58±3.21MPa, 3.5-fold: 47.75±2.55MPa and 4.0-fold: 45.53±1.97MPa. No difference was exhibited between DTS results for each sample except between 3.0-fold and 4.0-fold samples (p<0.05), and CS results showed no apparent difference existed among all samples (p<0.05). XRD analyses showed that BCP cement mostly converted to HA and microscopic features exhibited that HA crystals were clearly observed on surfaces of the BCP-cement at 24hours after mixing. The newly developed BCP cement was found to have adequate physical properties and HA formation for clinical use.

The salivary gland duct ligation model for the treatment of obstruction caused by salivary stones causes hypofunction of the salivary gland. However, sufficient results have not been obtained regarding the regeneration of acinar cells and the restoration of function, and the development of treatment methods is still ongoing. Here, we administered dental pulp stem cell-derived conditioned medium (DPSC-CM) containing various growth factors to mice and examined its effects. The main excretory duct of the submandibular gland was ligated; after 3 weeks, the ligation was released, and Dulbecco’s modified Eagle’s medium (DMEM) or DPSC-CM was administered biweekly via the right jugular vein. The mice were euthanized at 2, 4, and 8 weeks after the release of the ligation, and the submandibular glands were collected. After the release, the acinar cells had a time-dependent recovery. The DPSC-CM group exhibited a significant increase in the expression of progenitor cell marker cytokeratin 5 (CK5) at 4 weeks after the release of the ligation and acinar cell marker aquaporin 5 (AQP5) at 8 weeks compared with the control and DMEM groups by real-time RT-PCR. The administration of DPSC-CM in mice after the release of the submandibular main duct ligation promotes acinar cell regeneration.

In recent years, tooth erosion due to tooth root exposure has increased. This is associated with an increase in remaining teeth in the elderly and frequent ingestion of acidic foods. Fluoride application is a clinical method for preventing tooth erosion; however, dentin solubility after topical fluoride application, according to the type of erosive acid, has not been adequately investigated. We studied the characteristics of demineralization and acid resistance of dentin to four erosive acids and evaluated the efficacy of topical fluoride application in preventing tooth erosion. Small blocks with a smooth surface were prepared by mirror-finishing the labial side of a bovine tooth root. In the experimental group, acidulated phosphate fluoride (APF) was applied topically for 4 minutes, while the control group received no fluoride treatment. Both groups were immersed in a remineralization solution for 1 h at 37 °C. Five samples from each group were subjected to tooth erosion and demineralization by immersion in lactic acid, phosphoric acid, acetic acid, and citric acid for 6 h at 37 °C. Demineralization and dentin solubility were evaluated by calculating mineral loss (ΔZ) and lesion depth (Ld) from the average surface roughness (Sa), difference in height profile, and contact microradiogram (CMR). We also performed electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS) qualitative analysis to assess fluoride dynamics and properties of the compounds formed on the dentin surface after APF application. Samples with APF application showed greater resistance towards all four erosive acids. While a highly calcified layer was found with lactic and acetic acid, resistance was not adequate against citric acid, which has chelating properties. Fluoridated calcium formed on the tooth surface after topical fluoride application. Fluoride ions are taken up by peritubular dentin through the dentinal tubules, resulting in increased acid resistance.