Boron Accelerates Cultured Osteoblastic Cell Activity through Calcium Flux

A low concentration of boron (B) accelerates the proliferation and differentiation of mammalian osteoblasts. The aim of this study was to investigate the effects of 0.1 mM of B on the membrane function of osteoblastic cells in vitro. Genes involved in cell activity were investigated using gene expression microarray analyses. The Ca²⁺ influx and efflux were evaluated to demonstrate the activation of L-type Ca²⁺ channel for the Ca²⁺ influx, and that of Na⁺/K⁺-ATPase for the Ca²⁺ efflux. A real-time PCR analysis revealed that the messenger RNA (mRNA) expression of four mineralization-related genes was clearly increased after 3 days of culture with a B-supplemented culture medium. Using microarray analyses, five genes involved in cell proliferation and differentiation were upregulated compared to the control group. Regarding the Ca²⁺ influx, in the nifedipine-pretreated group, the relative fluorescence intensity for 1 min after adding B solution did not increase compared with that for 1 min before addition. In the control group, the relative fluorescence intensity was significantly increased compared with the experimental group (P < 0.05). Regarding the Ca²⁺ efflux, in the experimental group cultured in 0.1 mM of B-supplemented medium, the relative fluorescence intensity for 10 min after ouabain treatment revealed a significantly lower slope value compared with the control group (P < 0.01). This is the first study to demonstrate the acceleration of Ca²⁺ flux by B supplementation in osteoblastic cells. Cell membrane stability is related to the mechanism by which a very low concentration of B promotes the proliferation and differentiation of mammalian osteoblastic cells in vitro.

Association between total functional tooth unit score and hemoglobin A1c levels in Japanese community-dwelling individuals: the Nagasaki Islands study

BACKGROUND

It is widely recognized that periodontal disease is associated with diabetes mellitus. Periodontal disease is accompanied by inflammation of the periodontal tissue, impaired masticatory function, and the presence of periodontopathic bacteria, all of which may affect glycemic control. However, the exact relationship between these factors and glycemic control has not yet been established. In this study, we aimed to investigate the relationship between periodontal disease-related factors and glycemic control in Japanese community-dwelling individuals.

METHODS

We conducted a cross-sectional study involving 671 participants aged 29-92 (65.3 ± 12.1) years, using data from the Nagasaki Islands Study. Participants underwent routine medical examinations, including body mass index (BMI) and hemoglobin A1c (HbA1c) levels. Information on the participants' demographics (age and sex) and whether they were on diabetes medications, had an exercise habit, consumed alcohol, engaged in late-night eating, had regular dental checkups, and smoked was obtained using a self-administered questionnaire. Dental examinations were performed to examine dentition status, probing pocket depth, clinical attachment level (CAL), and bleeding on probing. Functional tooth units (FTUs), defined as pairs of occluding posterior teeth, were used as an indicator of occlusal support area. Saliva samples were collected and levels of two species of periodontopathic bacteria (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans) were determined using real-time polymerase chain reaction. We analyzed the association between HbA1c levels and variables related to periodontal status, masticatory function, and salivary levels of periodontopathic bacteria.

RESULTS

Bivariate analysis showed that HbA1c levels were significantly associated with age, sex, exercise habit, BMI, diabetes medications, CAL, salivary P. gingivalis level, number of teeth, and three FTU subcategories. In the multiple regression analysis, age, BMI, diabetes medications, and total FTU score (i.e., including natural teeth, implant-supported artificial teeth, fixed prostheses, and removable dentures) remained associated with HbA1c levels (B = 0.23, 0.14, 0.52, and - 0.12; p < 0.001, p < 0.001, p < 0.001, and p = 0.008, respectively).

CONCLUSIONS

In this community-based cross-sectional study, total FTU was significantly associated with HbA1c levels, independent of other risk factors. This suggests that reconstructed occlusal support areas, including dentures, are associated with glycemic control in the older population.

Dental Deposits Are Differentially Associated With Periodontal Conditions and the Number of Teeth in Japanese Community-Dwelling Individuals: The Nagasaki Islands Study

OBJECTIVE

This study aimed to determine how dental deposits are associated with periodontal conditions and the number of teeth in Goto Islands' residents.

BACKGROUND

Previous studies have shown that dental deposits increase the risk of developing periodontal diseases. However, the relationships between dental deposits and the periodontal/dentitional conditions in a super-aging society remain unclear.

MATERIALS AND METHODS

A cross-sectional study involving 671 participants (age: 65.0 ± 12.0 years) was conducted using data from the Nagasaki Islands Study (NaIS). Participants underwent a routine medical examination. Information on oral hygiene and smoking status was collected from a self-administered questionnaire. Dental examinations were conducted to determine the number of teeth, probing pocket depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP) ratio, calculus index (CI) score, and debris index (DI) score. Saliva samples were collected from the participants to determine the levels of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans by real-time polymerase chain reaction. Multivariable logistic regression analyses were performed to evaluate the relationships between dental deposits and periodontal/dentitional conditions.

RESULTS

Multivariable logistic regression analyses show that greater DI score was significantly associated with higher BOP ratio (OR = 2.51, 95% CI: 1.75-3.61), greater CAL (OR = 1.51, 95% CI: 1.02-2.23), and fewer teeth (OR = 1.70, 95% CI: 1.04-2.76). Greater CI score was significantly associated with a higher BOP ratio (OR = 2.18, 95% CI: 1.47-3.23), deeper PPD (OR = 2.04, 95% CI: 1.22-3.50), and more teeth (OR = 0.13, 95% CI: 0.08-0.23).

CONCLUSIONS

Debris and calculus deposition were associated with more severe periodontal conditions, but calculus deposition was strongly associated with more teeth. The association between calculus deposition and more teeth may be an emerging trend in super-aging societies, and future longitudinal studies are warranted to elucidate the changing relationship between calculus and number of teeth.