We investigated the effect of synthesized collagen model polypeptides consisting of a proline‐hydroxyproline‐glycine (poly(PHG)) sequence combined with porous alpha‐tricalcium phosphate (α‐TCP) particles on bone formation in a mandibular canine defect model. The porous α‐TCP particles were mixed with a poly(PHG) solution, and the obtained sponge was then cross‐linked and analyzed by scanning electron microscopy. The optimal mixing concentration of α‐TCP granules and the poly(PHG) solution was decided to be 0.15g/mL by compression testing. The osteoblastic differentiation with the ALP activity of human mesenchymal stromal cells (hMSCs) cultured on the poly(PHG)/α‐TCP was slightly greater than that of hMSCs cultured on the poly(PHG). Mandibular defects were analyzed in healthy beagles using micro‐computed tomography and histological evaluation. At 2 and 4 weeks, the volume density of new bone was grater in the poly(PHG)/α‐TCP group than in the group with only poly(PHG) (p<0.05); however, there was no difference at 8 weeks (p>0.05). Histological evaluation at 4 weeks after implantation revealed that the poly(PHG) had degraded and that newly formed bone was present on the surface of the α‐TCP particles. This study demonstrates that the composite created using porous α‐TCP particles and poly(PHG) is sufficiently adaptable for treating the mandibular canine defect model. (J Osaka Dent Univ 2023; 57: 223‐231)

Periodontal disease is an inflammatory condition caused by infection with periodontopathic bacteria. Plasmalogen (Pls) is a glycerophospholipid with anti-inflammatory properties. We investigated the effect of Pls on matrix metalloproteinase-1 (MMP-1) expression induced by TNFα in human gingival fibroblasts (HGFs). RT-qPCR and ELISA analysis were used to measure MMP-1 expression at the gene and protein level, respectively. TNFα increased MMP-1 expression in HGF at the gene and protein level. TNFα-induced MMP-1 gene expression was decreased by Pls pretreatment in a dose-dependent manner. At the protein level, TNFα-induced MMP-1 expression was significantly reduced by Pls pretreatment. These results indicate that Pls inhibits TNFα-induced MMP-1 expression in HGF at the gene and protein levels. These findings suggest that Pls may attenuate periodontal tissue destruction by suppressing MMP-1 in periodontal disease. (J Osaka Dent Univ 2023; 57: 233-237)

The periodontal ligament (PDL) has a key role in periodontal tissue regeneration. Proliferation of PDL-derived cells is closely related to the new formation of connective tissue attachment in periodontal wound healing. Induced pluripotent stem cells (iPS cells) are stem cells that have pluripotent differentiation potential and robust growth activity. The aim of this study was to examine the effect of iPS cell-derived cell extract (iPS-extract) on the proliferation of PDL cells in vitro. iPS-extract was obtained by the freeze/thaw and centrifugation of the cells. Cell proliferation was determined using the WST-8 assay. Cells in the proliferating state were examined by immunofluorescence staining for Ki67. PDL cell proliferation was enhanced in the presence of iPS-extract. Heat treatment of iPS-extract at 65°C did not change the effect of iPS-extract on PDL cell proliferation. iPS-extract significantly increased the number of positive cells for Ki67. Cell extract from iPS cells enhanced the proliferation of PDL cells and this function was not mediated by the protein content of the extract. These results indicate that iPS-extract may have the potential to regenerate periodontal tissues by promoting PDL cell proliferation. (J Osaka Dent Univ 2023; 57: 239-243)

Although choking accounts for over 5,000 deaths annually in the US, in Japan, where the population is only 40% that of the US, accidental suffocation is even greater, with 7,986 deaths reported in 2021. Mochi, a traditional food made from rice, is a common cause of foreign body airway obstruction (FBAO) during the New Year's holidays. We investigated the effect of temperature on the food texture of three types of commercially available mochi using various measurements. The samples were examined at six different temperatures, and the results were statistically evaluated. We investigated the effect of various properties of the mochi. The results showed that hardness increased as temperature decreased, while adhesiveness decreased slightly. Cohesiveness and springiness had no significant correlation with temperature. Stickiness increased as temperature decreased, except for sample B which did not exhibit any changes. Chewiness increased as temperature decreased in all samples. Sample C was slightly harder and stickier, and less cohesive than the others. These findings provide useful information on the textural changes that occur in mochi at different temperatures. (J Osaka Dent Univ 2023; 57: 245-253)

Malocclusion with impacted teeth is often encountered in orthodontic treatment. We investigated the influence of impacted maxillary central incisors on maxillofacial morphology in order to create normal occlusion by orthodontic treatment. We examined 15 males and 15 females who visited the Department of Orthodontics, Osaka Dental University Hospital, who had impacted maxillary central incisors and who were classified as having Hellman dental developmental stage IIIB. The maxillofacial morphology, the direction of the long axis of the impacted teeth, and root axis curvature were studied using cephalometric radiographs. We found that there was correlation between the direction of the long axis of the impacted tooth and N-Me, ANS-Me, Is-Is' and Mo-Ms in males, and between the long axis of the tooth and ∠SNA in females. There was also correlation between the root axis curvature and ∠SNA and Mo-Mi in females. The maxillofacial morphology of most of the cases was skeletal Class I. Although the L1 to Mandibular values were small and the mandibular anterior teeth were inclined lingually, there was no mandibular retrusion. In addition, although the impacted teeth did not inhibit growth and development of the nasomaxillary complex, there was a negative correlation between the direction of central incisor impaction and the facial height. (J Osaka Dent Univ 2023; 57: 255-262)

We used cephalograms to investigate the correlation between the craniofacial morphology and the mandibular symphysis in Chinese children, measuring the angles between the mandibular plane and symphysis, and the angles between the symphysis and mandibular central incisor. We observed the correlations in males with skeletal Class I between ∠SNA and Idm-Me (mm); between ∠SNB and Idm-Me (mm); between ∠ANB and ∠Idm-X to MP; between FMA and ∠Idm-Me to MP, ∠X-Me to MP, and Thickness Pogonion; between IMPA and ∠Idm-Me to MP, ∠Idm-X to MP, ∠X-Me to MP, and Thickness Pogonion; and between Gn-Cd and Idm-Me (mm), and Thickness Pogonion. In males with skeletal Class II, correlations were observed between ∠SNB and Thickness Pogonion; between ∠ANB and ∠Idm-Me to MP, and ∠L1 to X-Me; between FMA and ∠L1 to Idm-X, and ∠L1 to X-Me; between IMPA and ∠Idm-Me to MP, ∠Idm-X to MP, ∠X-Me to MP, ∠L1 to Idm-X, and ∠L1 to X-Me; and between Gn-Cd and Idm-Me (mm), Thickness Point B, and Thickness Pogonion. In females with skeletal Class I, correlations were observed between FMA and ∠X-Me to MP, ∠L1 to Idm-X, and ∠Thickness Pogonion; between IMPA and ∠Idm-X to MP, ∠X-Me to MP, and ∠L1 to X-Me; and between Gn-Cd and Idm-Me (mm), and Thickness Pogonion. In females with skeletal Class II, correlations were observed between ∠SNA and ∠Idm-Me to MP, ∠Idm-X to MP, and ∠X-Me to MP; between ∠SNB and ∠Idm-Me to MP, ∠Idm-X to MP, and ∠X-Me to MP; between FMA and ∠L1 to Idm-X, and Thickness Point B; between IMPA and ∠Idm-Me to MP, ∠Idm-X to MP, ∠X-Me to MP, ∠L1 to X-Me, and Thickness Point B; and between Gn-Cd and ∠L1 to X-Me, and Idm-Me (mm). These results suggested the importance of monitoring movement of the mandibular anterior teeth during orthodontic treatment because skeletal differences affect the inclination of these teeth and the morphology of the symphysis. (J Osaka Dent Univ 2023; 57: 263-273)

Regular dental visits are an important opportunity for detecting oral cancer. We investigated the relation between the frequency of previous dental visits and the prognosis of oral cancer using an administrative claims database. We obtained longitudinal data from the Japanese Insurance Database on 1,154 oral cancers patients. The results of the logistic regression model showed that a regular dental visit at least once annually in 2 years was negatively associated with lymph node metastasis (OR=0.57, 95% CI=0.38-0.85, p=0.006). However, other factors such as age, sex, work status, and tumor site were not significantly associated with lymph node metastasis. Based on our findings, dental clinicians should educate patients on the importance of regular dental visits not only for the routine maintenance of their oral health, but also for oral cancer prevention. (J Osaka Dent Univ 2023; 57: 275-281)

We investigated the incidence of temporomandibular joint disorders in rheumatoid arthritis (RA) patients. We studied the demographic data of 38 RA patients and examined their clinical and radiographic findings. In addition, we statistically examined the correlation between the duration of the illness, the radiographic findings, and the Larsen grade. We found no bony ankylosis of the TMJ, the maximum mouth opening was 38.3 mm, and there was almost no limitation in joint range of motion. Some form of changes in the bone and resorption were observed in the radiographic findings in condyles of 67 joints (88%). On statistical analysis, only a weak correlation was observed between the duration of illness and radiographic findings of the condyle (r=0.464), only a weak correlation was observed between Larsen's grade and radiographic finding (r=0.489), and a strong correlation was observed between left and right condyle deformation in the radiographic findings (r=0.795). These results suggest that the TMJ is less affected by RA than other joints. (J Osaka Dent Univ 2023; 57: 283-287)

We previously reported on the accessibility of dental services in Japan using the Geographic Information System, evaluating the supply and demand for home dental care using a new approach based on previous methods. For this study, we obtained population data in 2019 from the Japanese National Census and data retrieved from the e-Stat website. In addition, we purchased data from the Kokusai Kogyo Company on dental clinics and offices specializing in home dental care in 2019. We further modified the dental accessibility indicators by adding transportation network information. The information we obtained for the new accessibility index ratio (AIR), data which was converted into traffic time, was considerably different from the previous data, which only considered the distance from dental clinics specializing in home dental care to the patients. The accessibility indicator we defined may be a useful tool for revealing the demand for and supply of home dental care in Japan. (J Osaka Dent Univ 2023; 57: 289-293)

Candida albicans is a common pathogen, especially in immunocompromised patients. What is concerning is that this pathogen is displaying increasing resistance to azole drugs, which are commonly used to treat it. We investigated the antifungal activity of Moringa oleifera leaves against C. albicans. The fungicidal effect of C. albicans exposed to Moringa oleifera leaves was determined using adenosine triphosphate (ATP) bioluminescence. Moringa oleifera leaves showed antifungal activity against C. albicans with a minimum inhibitory concentration (MIC) of 50 μg/mL. Additionally, at the MIC, the Moringa oleifera leaves significantly reduced ATP-leakage. This study provides sufficient evidence of the in vitro antifungal effects of Moringa oleifera leaves against C. albicans. (J Osaka Dent Univ 2023; 57: 295-299)

In Japanese, obesity is a lifestyle-related disease and major risk factor for type 2 diabetes mellitus. Asians, including the Japanese, are reported to have a higher incidence of diabetes mellitus because they have a lower body mass index and higher body fat percentage. In this study, we performed a morphological analysis of the mucosal epithelium of the palatal gingiva of the maxillary first molar in normal rats and in Spontaneously Diabetic Torii fatty rats, a model of obese type 2 diabetes mellitus (ODM). The superficial morphology of the mucosal epithelium showed epithelial cells of various sizes and nearly exfoliated epithelial cells in the ODM group. The mucosal epithelium was significantly thicker in the ODM group than in the normal group (p<0.01). The number of cells in the granular and prickle layers was significantly greater in the ODM group than in the normal group (p<0.01), and the number of epithelial papilla was significantly lower in the ODM group than in the normal group (p<0.01). In conclusion, hyperglycemia with ODM thickens the mucosal epithelium of the palatal gingiva of the maxillary first molar causing the epithelial papillae to be lower and epithelial cells of the keratinized layer to detach more easily. (J Osaka Dent Univ 2023; 57: 301-312)

In order to meet the needs of a globalized society, there is a growing demand for dental technicians and dental hygienists who are fluent in English. However, problems occur at the workplace due to the lack of English proficiency among health care providers. Students studying to work in this field are often not confident of their language abilities. English education needs to be enhanced at the workplace as well as in schools. Based on the concept of English for specific purposes (ESP) education, we did a needs analysis on the status of the English proficiency of dental technician and hygiene students along with the type of English language skill thought necessary for each department. Based on proficiency test results and text analysis of a questionnaire, it became clear that students in both departments feel English proficiency that centers on communication skills is necessary for their careers. The objective for using English differed between the departments. Technician students sensed the necessity to communicate with patients, clients, and colleagues both domestically and abroad while dental hygiene students felt a need to communicate with foreign patients domestically. These findings can contribute to the structuring of the curriculum and teaching plans for practical dental English education. (J Osaka Dent Univ 2023; 57: 313-320)

We statistically examined the effect of background conditions and coexisting conditions on sleep apnea syndrome (SAS) patients. Thirty-three patients who had been examined using polysomnography (PSG) from April 1, 2019 to December 31, 2020 in Osaka Dental University Hospital were recruited for this study. They were divided into two groups, the severe group (apnea hypopnea index (AHI) over 25) and mild to moderate group (AHI between 5 and 25). The effect of SAS severity on background conditions such as age, gender and obesity, and the prevalence of coexisting conditions, including hypertension, diabetes mellitus (DM), metabolic syndrome (MS) and chronic kidney disease (CKD), were examined with the χ2 test, Student's t-test and multivariate analysis (p<0.05). SAS severity related to age, gender, obesity and hypertension, but not to MS, DM or CKD. Because MS, DM and CKD are closely related to visceral fat, the SAS severity might be related to systemic obesity rather than visceral obesity. (J Osaka Dent Univ 2023; 57: 321-323)

Intrusive luxation with a crown fracture of the permanent teeth is a rare and severe injury, and knowledge regarding the management of these injuries is limited. A 9-year-old boy fell down the stairs at school, resulting in intrusive luxation of his maxillary central incisors complicated by mid-crown fractures involving the dentin. The root formation was almost complete. The pulp of the left central incisor was exposed. Both teeth were surgically repositioned. The fractured fragments were reattached, and endodontic treatment was performed due to pulp necrosis. The patient was followed-up monthly for 43 months. At 43-months, the permanent central incisors were clinically and radiologically satisfactory. (J Osaka Dent Univ 2023; 57: 325-330)