Tooth loss and osteoporosis: to assess the association between osteoporosis status and tooth number

Association between oral health and locomotive syndrome: a cross-sectional study in Japanese adults

BACKGROUND

Many studies have examined the association between oral health, care needs, and physical function, but few have focused on the association between oral health and locomotive syndrome (LS). We examined the association between LS and oral-health status, such as the number of teeth and chewing function, in an adult population.

METHODS

The study included 2888 participants who underwent examinations of motor function and oral health. Individuals with LS stage 1 or higher were classified as having LS, while others were classified as not having it. Logistic regression analysis was performed using the presence or absence of LS as the dependent variable and age, sex, smoking status, drinking habit, exercise habit, walking speed, history of stroke, bone density, body mass index, metabolic syndrome, chewing function, and the number of teeth as independent variables to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for each independent variable.

RESULTS

When the number of teeth and chewing function were included separately in multivariate analyses, the OR for LS was significantly higher for participants with 0-19 teeth than for those with 28 teeth, and for participants with poor chewing function than for those with good function (adjusted ORs, 1.47 [95% CI, 1.01-2.15] and 1.73 [95% CI, 1.37-2.18], respectively). In analyses that included tooth number and chewing function as a combined independent variable, relative to individuals with 28 teeth and good masticatory function, the adjusted ORs were 2.67 (95% CI, 1.57-4.52) for those with 28 teeth and poor chewing function, 1.63 (95% CI, 1.20-2.22) for those with 20-27 teeth and poor chewing function, and 1.83 (95% CI, 1.06-3.18) for those with 0-19 teeth and poor chewing function.

CONCLUSION

Having fewer teeth and poor chewing function may be associated with LS. The maintenance of masticatory function may be important to prevent LS in adulthood.

Synergic Action of Systemic Risedronate and Local Rutherpy in Peri-implantar Repair of Ovariectomized Rats: Biomechanical and Molecular Analysis

Postmenopausal osteoporosis and poor dietary habits can lead to overweightness and obesity. Bisphosphonates are the first-line treatment for osteoporosis. However, some studies show that they may increase the risk of osteonecrosis of the jaw. Considering the antimicrobial, angiogenic and vasodilatory potential of nitric oxide, this study aims to evaluate the local activity of this substance during the placement of surface-treated implants. Seventy-two Wistar rats were divided into three groups: SHAM (SHAM surgery), OVX + HD (ovariectomy + cafeteria diet), and OVX + HD + RIS (ovariectomy + cafeteria diet + sodium risedronate treatment), which were further subdivided according to the surface treatment of the future implant: CONV (conventional), TE10, or TE100 (TERPY at 10 or 100 μM concentration); n = 8 per subgroup. The animals underwent surgery for implant installation in the proximal tibia metaphysis and were euthanized after 28 days. Data obtained from removal torque and RT-PCR (OPG, RANKL, ALP, IBSP and VEGF expression) were subjected to statistical analysis at 5% significance level. For biomechanical analysis, TE10 produced better results in the OVX + HD group (7.4 N/cm, SD = 0.6819). Molecular analysis showed: (1) significant increase in OPG gene expression in OVX groups with TE10; (2) decreased RANKL expression in OVX + HD + RIS compared to OVX + HD; (3) significantly increased expressions of IBSP and VEGF for OVX + HD + RIS TE10. At its lowest concentration, TERPY has the potential to improve peri-implant conditions.

Biochemical and immunohistochemical examination of the effects of ephedrine in rat ovary tissue

PURPOSE

It was aimed to investigate the biochemical and immunohistochemical effects of ephedrine (EPH) in bilateral ovariectomized rats.

METHODS

Twenty-four Sprague Dawley female rats were divided into three groups: control group: The abdomen was opened and closed without any treatment; ischemia-reperfusion (IR) group: 2 h of ischemia followed by 2 h of reperfusion were allowed to cause IR injury; IR+EPH group: oral EPH solution (5 mg/kg) was administered for 28 days.

RESULTS

Biochemical parameters were statistically significant in group comparisons. Increased interleukin-6 (IL-6) expression, degenerative preantral and antral follicle cells and inflammatory cells around blood vessels were seen in IR group. Negative IL-6 expression was observed in seminal epithelial cells, preantral and antral follicle cells in IR+EPH group. While caspase-3 activity increased in granulosa cells and stromal cells in IR group, caspase-3 expression was negative in preantral and antral follicle cells in the germinal epithelium and cortex in IR+EPH group.

CONCLUSIONS

The effect of apoptosis, which occurs with the signaling that starts in the cell nucleus, caused the cessation of the stimulating effect at the nuclear level after EPH administration, and a decrease in the antioxidative effect in IR damage and inflammation in the apoptotic process.

Functional tooth number in the posterior region associated serum ucOC levels

Purpose

The purpose of this study was to investigate serum undercarboxylated osteocalcin (ucOC) levels in partially edentulous patients scheduled to receive implant treatment and determine the association between ucOC levels, vegetable intake, vitamin K, dietary fiber intake, and functional tooth number in the posterior region (p-FTN).

Methods

A total of 46 patients (20 male and 26 female, 61.9 ± 12.7 years old) were included. The association among serum ucOC levels, vegetable intake, vitamin K and dietary fiber intake was assessed using Spearman’s rank correlation coefficient and binary logistic regression analysis.

Results

In total, 35% of patients (16/46 subjects) showed an abnormally high ucOC level (≧ 4.5 ng/mL). p-FTN showed a weak positive correlation with vegetable intake, vitamin K and dietary fiber intake (r = 0.28, 0.21, and 0.14, respectively) and a significant negative correlation with ucOC levels (r = − 0.51). Multivariate analysis demonstrated that p-FTN as well as vitamin K intake showed a significant negative association with serum ucOC levels.

Conclusions

More than one-third of patients showed abnormally high ucOC levels. p-FTN showed a negative association with serum ucOC levels, which indicated the possibility that oral status affected bone quality.

Loss of KDM4B impairs osteogenic differentiation of OMSCs and promotes oral bone aging

Aging of craniofacial skeleton significantly impairs the repair and regeneration of trauma-induced bony defects, and complicates dental treatment outcomes. Age-related alveolar bone loss could be attributed to decreased progenitor pool through senescence, imbalance in bone metabolism and bone-fat ratio. Mesenchymal stem cells isolated from oral bones (OMSCs) have distinct lineage propensities and characteristics compared to MSCs from long bones, and are more suited for craniofacial regeneration. However, the effect of epigenetic modifications regulating OMSC differentiation and senescence in aging has not yet been investigated. In this study, we found that the histone demethylase KDM4B plays an essential role in regulating the osteogenesis of OMSCs and oral bone aging. Loss of KDM4B in OMSCs leads to inhibition of osteogenesis. Moreover, KDM4B loss promoted adipogenesis and OMSC senescence which further impairs bone-fat balance in the mandible. Together, our data suggest that KDM4B may underpin the molecular mechanisms of OMSC fate determination and alveolar bone homeostasis in skeletal aging, and present as a promising therapeutic target for addressing craniofacial skeletal defects associated with age-related deteriorations.

Transplantation of bone marrow mesenchymal stem cells and fibrin glue into extraction socket in maxilla promoted bone regeneration in osteoporosis rat

AIMS

Bone defect repair in osteoporosis remains a tremendous challenge for clinicians due to increased bone metabolism resulted from estrogen deficiency. This study aims to investigate the effect of bone marrow mesenchymal stem cells (BMSCs) combined with fibrin glue (FG) in the extraction socket healing process of osteoporosis rats, as well as estimate the role of estrogen receptors (ERs) played in BMSCs differentiation in vitro and in the alveolar bone reconstruction process in vivo.

MAIN METHODS

Forty rats were randomly divided into four groups, under general anesthesia, three groups underwent bilateral ovariectomy(OVX) and one group with the sham operation. Three months later, the osteogenic ability of BMSCs, isolated from healthy and osteoporosis rats, respectively, was tested. The ERα and ERβ mRNA expression in BMSCs was also evaluated by RT-PCR analysis. In vivo experiment, Micro-CT detection, histological and immunofluorescent analysis, tissue PCR was conducted up to 2, 4 and 6 weeks after transplantation of BMSCs/FG to assess the newly formed bone in the extraction socket.

KEY FINDINGS

The BMSCs from osteoporosis rats displayed weaker osteogenic potential and lower ERs expression compared with the BMSCs from healthy rats. Newly formed bone tissue filled the socket defect in BMSCs/FG treated VOX rats after six weeks, which was comparable to the sham group, while reduced ERs expression was found in the regenerated bone of the OVX group.

SIGNIFICANCE

The BMSCs seeded within FG might provide an alternative therapeutic method for repairing the extraction socket defect in osteoporosis condition.

Oral health and emotional well-being in premenopausal and postmenopausal women: a cross-sectional cohort study

Background

Menopause, the absence of ovarian sex steroids, is frequently accompanied by emotional and physiological changes in a woman´s body, as well as oral health changes. The present study aimed to evaluate the association between the periodontal health status and emotional and physical well-being among postmenopausal women (PMW) in comparison with regularly menstruating premenopausal women (RMPW).

Methods

A total of 115 women (PMW, n = 56, mean age ± SD: 54 ± 5; RMPW, n = 59, mean age ± SD: 41 ± 4) received a comprehensive medical assessment and a full-mouth oral examination. All completed the Women’s Health Questionnaire (WHQ) to measure emotional and physical well-being. The corresponding bone mineral density (BMD) scores were obtained from participants´ medical records.

Results

Tooth loss was significantly higher in PMW than RMPW after adjusting for age (3.88 ± 2.41 vs 2.14 ± 2.43, p < 0.05). No significant difference was found in the prevalence of periodontitis between the two groups (PMW: 39.2%, RMPW: 32.2%, p > 0.05). The prevalence of periodontitis was associated with fewer daily brushing sessions in PMW (p = 0.021). Based on the WHQ, both PMW and RMPW with periodontitis had higher ‘’depressed mood’’ scores compared to periodontally healthy women (p = 0.06 and p = 0.038, respectively). The women who reported fewer daily toothbrushing sessions found to have higher depressive mood scores (p = 0.043).

Conclusions

Presence of periodontitis is associated with the emotional and physical well-being of women and reinforcement of oral healtcare is recommended at different stages of a woman’s life including menopause to reduce the risk for early tooth loss in women.

Detecting genetic signals of selection in heavily bottlenecked reindeer populations by comparing parallel founder events

Founder populations are of special interest to both evolutionary and conservation biologists, but the detection of genetic signals of selection in these populations is challenging due to their demographic history. Geographically separated founder populations likely to have been subjected to similar selection pressures provide an ideal but rare opportunity to overcome these challenges. Here we take advantage of such a situation generated when small, isolated founder populations of reindeer were established on the island of South Georgia, and using this system we look for empirical evidence of selection overcoming strong genetic drift. We generated a 70 k ddRADseq single nucleotide polymorphism database for the two parallel reindeer founder populations and screened for signatures of soft sweeps. We find evidence for a genomic region under selection shared among the two populations, and support our findings with Wright-Fisher model simulations to assess the power and specificity of interpopulation selection scans-namely Bayescan, OutFLANK, PCadapt and a newly developed scan called Genome Wide Differentiation Scan (GWDS)-in the context of pairwise source-founder comparisons. Our simulations indicate that loci under selection in small founder populations are most probably detected by GWDS, and strengthen the hypothesis that the outlier region represents a true locus under selection. We explore possible, relevant functional roles for genes in linkage with the detected outlier loci.

Therapeutic effect of localized vibration on alveolar bone of osteoporotic rats

OBJECTIVES

Vibration, in the form of high frequency acceleration (HFA), stimulates alveolar bone formation under physiologic conditions and during healing after dental extractions. It is not known if HFA has an anabolic effect on osteoporotic alveolar bone. Our objective is to determine if HFA has a regenerative effect on osteoporotic alveolar bone.

METHODS AND MATERIALS

Adult female Sprague-Dawley rats were divided into five groups: 1) Ovariectomized Group (OVX), 2) Sham-OVX Group that received surgery without ovariectomy, 3) OVX-HFA Group that was ovariectomized and treated daily with HFA, 4) OVX+Static Force Group that was ovariectomized and received the same force as HFA, but without vibration, and 5) Control Group that did not receive any treatment. All animals were fed a low mineral diet for 3 months. Osteoporosis was confirmed by micro-CT of the fifth lumbar vertebra and femoral head. HFA was applied to the maxillary first molar for 5 minutes/day for 28 and 56 days. Maxillae were collected for micro-CT, histology, fluorescent microscopy, protein and RNA analysis, and three-point bending mechanical testing.

RESULTS

Micro-CT analysis revealed significant alveolar bone osteoporosis in the OVX group. Vibration restored the quality and quantity of alveolar bone to levels similar to the Sham-OVX group. Animals exposed to HFA demonstrated higher osteoblast activity and lower osteoclast activity. Osteogenic transcription factors (RUNX2, Foxo1, Osterix and Wnt signaling factors) were upregulated following vibration, while RANKL/RANK and Sclerostin were downregulated. HFA did not affect serum TRAcP-5b or CTx-1 levels. The osteogenic effect was highest at the point of HFA application and extended along the hemimaxillae this effect did not cross to the contra-lateral side.

CONCLUSIONS

Local application of vibration generated gradients of increased anabolic metabolism and decreased catabolic metabolism in alveolar bone of osteoporotic rats. Our findings suggest that HFA could be a predictable treatment for diminished alveolar bone levels in osteoporosis patients.

FOXO1 Mediates Advanced Glycation End Products Induced Mouse Osteocyte-Like MLO-Y4 Cell Apoptosis and Dysfunctions

Osteocyte plays an essential role in bone metabolism by regulating osteoblast and osteoclast activities. Dysfunction or apoptosis of osteocyte will severely endanger the bone homeostasis and result in bone diseases such as osteoporosis. Osteoporosis has been considered as one of the diabetes complications; however, the mechanism is still to be discovered. Advanced glycation end products (AGEs), as the main pathogenic factor of diabetes mellitus, have the capacity to induce osteocyte apoptosis thus sabotaging bone homeostasis. Here, we examined the role of AGE during osteocyte apoptosis and how this effect would affect osteocyte's regulation of osteoblast and osteoclast. Mouse osteocyte-like MLO-Y4 cells were used to study the properties of osteocyte and to examine its biological and pathological function. MTT assay and Annexin V assay showed that AGE significantly induce MLO-Y4 cell apoptosis. qPCR and Western blot results have shown that AGE upregulates proapoptotic gene p53 and its downstream target gene Bax, which leads to enhanced activation of caspase-3, thus inducing apoptosis in MLO-Y4 cells. Increased expression of sclerostin and RANKL in osteocytes has shown that AGE induces osteocyte dysfunction thus severely damaging the bone homeostasis by decreasing osteoblast and increasing osteoclast activities. Furthermore, the role of the transcription factor FOXO1, which is intensely associated with apoptosis, has been determined. Western blot has shown that AGE significantly decreases Akt activities. Immunofluorescence has shown that AGE promotes FOXO1 nuclei localization and enhances FOXO1 expression. Silencing of FOXO1 suppressed AGE-enhanced apoptosis; mRNA and protein expressions of cleaved caspase-3, sclerostin, and RANKL were downregulated as well. Moreover, exogenous FOXO1 increased caspase-3 mRNA levels and caspase-3 transcriptional activity. Lastly, ChIP assay has established the capacity of FOXO1 binding directly on the caspase-3, sclerostin, and RANKL promoter region in AGE environment, providing the mechanism of the AGE-induced osteocyte apoptosis and dysfunction. Our results have shown that FOXO1 plays a crucial role in AGE-induced osteocyte dysfunction and apoptosis through its regulation of caspase-3, sclerostin, and RANKL. This study provides new insight into diabetes-enhanced risk of osteoporosis given the critical role of AGE in the pathogenesis of diabetes and the essential part of osteocyte in bone metabolism.

Evaluating the possible association between systemic osteoporosis and periodontal disease progression in postmenopausal women

To evaluate the association between systemic osteoporosis and periodontal diseases in postmenopausal women. A total of 300 women aged (50-70 years) were divided into an osteoporotic (OP) group (n = 150) and non-osteoporotic (NOP) group (n = 150) depending on BMD measured using (DXA) at the femoral neck and lumbar spine. Periodontal examination including PI, GI, PPD, and CAL was measured. A standard digital dental panoramic radiograph was taken for each patient and analyzed using specially developed software graphic program to assess the alveolar bone level and BMD. Elemental analysis of root surfaces of extracted teeth was done for detecting Ca, P, F, Mg, and K using (LIBS). Results showed the differences between both groups were not statistically significant in PI, GI, and PPD. A statistically significant difference was found between both groups in CAL, the distance between CEJ-AC and alveolar bone density. Elemental analysis of the root surfaces revealed that Ca was statistically significantly less in the OP group while the differences between both groups regarding F and P were not statistically significant. Mg and K found to be significantly more in the OP group than in the NOP group. To conclude osteoporosis is certainly a risk factor for periodontal disease and seems to plays a vital role in disease progression.

Respective role of membrane and nuclear estrogen receptor (ER) α in the mandible of growing mice: Implications for ERα modulation

Estrogens play an important role in bone growth and maturation as well as in the regulation of bone turnover in adults. Although the effects of 17β-estradiol (E2) are well documented in long bones and vertebrae, little is known regarding its action in the mandible. E2 actions could be mediated by estrogen receptor (ER) α or β. ERs act primarily as transcriptional factors through two activation functions (AFs), AF1 and AF2, but they can also elicit membrane-initiated steroid signaling (MISS). The aim of the present study was to define ER pathways involved in E2 effects on mandibular bone. Using mice models targeting ERβ or ERα, we first show that E2 effects on mandibular bone are mediated by ERα and do not require ERβ. Second, we show that nuclear ERαAF2 is absolutely required for all the actions of E2 on mandibular bone. Third, inactivation of ERαMISS partially reduced the E2 response on bone thickness and volume, whereas there was no significant impact on bone mineral density. Altogether, these results show that both nuclear and membrane ERα are requested to mediate full estrogen effects in the mandible of growing mice. Finally, selective activation of ERαMISS is able to exert an effect on alveolar bone but not on the cortical compartment, contrary to its protective action on femoral cortical bone. To conclude, these results highlight similarities but also specificities between effects of estrogen in long bones and in the mandible that could be of interest in therapeutic approaches to treat bone mass reduction. © 2018 American Society for Bone and Mineral Research.

Quantitative Ultrasound of the Mandible as a Novel Screening Approach for Osteoporosis

This study used an axial transmission quantitative ultrasound (QUS) device to assess mandibular bone strength. The aim of the study was first to establish the precision and repeatability of the axial transmission QUS measurement for a range of mandibular anatomic sites, and second to investigate the ability of the modality to differentiate between osteoporotic subjects and a control group. Three groups of adult Caucasian women were recruited: (1) healthy premenopausal women (n = 26), (2) healthy postmenopausal women (n = 48), and (3) women with osteoporosis (n = 53). Subjects were excluded from groups 1 and 2 if they had any pre-existing bone conditions. Speed of sound (SOS) measurements were taken from the mandible using an OmniSense multisite QUS device. Group 3 had dual-energy X-ray absorptiometry scans of the lumbar spine and femur. The most suitable site on the mandible was determined by repeat SOS measurements in 10 healthy premenopausal subjects, at 5 different sites. The parasymphysis site had the lowest root mean squared coefficient of variation at 0.74%, and was chosen as the most suitable site for mandibular SOS measurements. Group 1 and group 2 had significantly higher mean SOS measurements than the osteoporotic subjects (group 3), with means of 3683 m/s (210), 3514 m/s (221), and 3312 m/s (264), respectively. A 1-way analysis of variance confirmed a statistically significant difference between mean SOS measurements from the 3 groups (p < 0.0001). Axial transmission QUS of the mandible can differentiate between subjects with osteoporosis and a healthy control group, and shows potential for use as a screening tool for osteoporosis.

Systematic analysis of lncRNAs, miRNAs and mRNAs for the identification of biomarkers for osteoporosis in the mandible of ovariectomized mice

Osteoporosis is a complex and multifactorial disease caused by an imbalance between bone formation and resorption. Post-menopausal women with endogenous estrogen deficiency suffer from systemic bone loss and osteoporosis, and are at high risk of this affecting the jaw bones. MicroRNAs (miRNAs or miRs) have been implicated in the mechanisms of metabolic bone diseases and are expressed at differential levels in alveolar bone following ovariectomy. In the present study, we systematically analyzed the expression profiles of miRNAs, mRNAs and long non-coding RNA (lncRNAs) in the mandible of ovariectomized (OVX) mice. A complex miRNA-mRNA-lncRNA regulatory network was constructed based on differentially expressed RNAs. Two core differentially expressed genes (DEGs), namely, LRP2 binding protein (Lrp2bp) and perilipin 4 (Plin4), significantly influenced the network targeted by differentially expressed miRNAs. Moreover, peroxisome proliferator-activated receptor (PPAR) and insulin signaling pathways were significantly dysregulated in the mandible of OVX mice. Several differentially expressed lncRNAs were also implicated in the two signaling pathways, which influenced mandible development by forming competing endogenous RNA. On the whole, our data indicate that the comprehensive analysis of miRNAs, mRNAs and lncRNAs provides insight into the pathogenesis of estrogen deficiency-induced osteoporosis in the mandible. This study proposes potential biomarkers for diagnosis or therapeutic targets for osteoporosis which may aid in the development of novel drugs for the treatment of osteoporosis.

Providing Flaxseed Oil but Not Menhaden Oil Protects against OVX Induced Bone Loss in the Mandible of Sprague-Dawley Rats

Higher intakes of polyunsaturated fatty acids (PUFA) are associated with benefits at several skeletal sites in postmenopausal women and in rodent models, but the effect of PUFA-containing oils on tooth-supporting alveolar bone of the mandible has not been studied. Moreover, direct comparison of the effect of flaxseed oil (a source of alpha-linolenic acid (ALA)) and menhaden oil (a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) is unknown. One-month old female Sprague-Dawley rats (n = 48) were randomized to and fed a diet containing flaxseed oil or menhaden oil from one to six months of age. At three months of age, rats were randomized to receive SHAM or ovariectomy (OVX) surgery (n = 12/diet). The inter-radicular septum below the first molar of the mandible was imaged at 6 months of age (study endpoint) using micro-computed tomography (μCT) at a resolution of 9 μm. As expected, OVX significantly reduced percent bone volume (BV/TV), connectivity density (Conn. D.), trabecular number (Tb. N.), and increased trabecular separation (Tb. Sp.) compared to SHAM rats (p < 0.001). However, post hoc analysis revealed these differences were present in rats fed menhaden oil but not those fed flaxseed oil. These results suggest that providing flaxseed oil, possibly through its high ALA content, provides protection against the OVX-induced alveolar bone loss in rats.

The effects of implant topography on osseointegration under estrogen deficiency induced osteoporotic conditions: Histomorphometric, transcriptional and ultrastructural analysis

Compromised bone quality and/or healing in osteoporosis are recognised risk factors for impaired dental implant osseointegration. This study examined the effects of (1) experimentally induced osteoporosis on titanium implant osseointegration and (2) the effect of modified implant surface topography on osseointegration under osteoporosis-like conditions. Machined and micro-roughened surface implants were placed into the maxillary first molar root socket of 64 ovariectomised and sham-operated Sprague-Dawley rats. Subsequent histological and SEM observations showed tissue maturation on the micro-rough surfaced implants in ovariectomised animals as early as 3days post-implantation. The degree of osseointegration was also significantly higher around the micro-rough implants in ovariectomised animals after 14days of healing although by day 28, similar levels of osseointegration were found for all test groups. The micro-rough implants significantly increased the early (day 3) gene expression of alkaline phosphatase, osteocalcin, receptor activator of nuclear factor kappa-B ligand and dentin matrix protein 1 in implant adherent cells. By day 7, the expression of inflammatory genes decreased while the expression of the osteogenic markers increased further although there were few statistically significant differences between the micro-rough and machined surfaces. Osteocyte morphology was also affected by estrogen deficiency with the size of the cells being reduced in trabecular bone. In conclusion, estrogen deficiency induced osteoporotic conditions negatively influenced the early osseointegration of machined implants while micro-rough implants compensated for these deleterious effects by enhancing osteogenic cell differentiation on the implant surface.

STATEMENT OF SIGNIFICANCE

Lower bone density, poor bone quality and osseous microstructural changes are all features characteristic of osteoporosis that may impair the osseointegration of dental implants. Using a clinically relevant trabecular bone model in the rat maxilla, we demonstrated histologically that the negative effects of surgically-induced osteoporosis on osseointegration could be ameliorated by the biomaterial's surface topography. Furthermore, gene expression analysis suggests this may be a result of enhanced osteogenic cell differentiation on the implant surface.

Transplantation of osteoporotic bone marrow stromal cells rejuvenated by the overexpression of SATB2 prevents alveolar bone loss in ovariectomized rats

Estrogen-deficient osteoporosis is an aging-related disease with high morbidity that not only significantly increases a woman's risk of fragility fracture but is also associated with tooth and bone loss in the supporting alveolar bone of the jaw. Emerging evidence suggests that the aging of bone marrow stromal cells (BMSCs) contributes to the development of osteoporosis. In this study, we aimed to investigate the role of the special AT-rich sequence-binding protein 2 (SATB2), a stemness and senescence regulator of craniofacial BMSCs, in rat ovariectomy-induced alveolar osteoporosis. We also sought to determine whether transplantation of SATB2-modified BMSCs could ameliorate estrogen deficient alveolar bone loss. Our data revealed that BMSCs from ovariectomy-induced alveolar bone exhibited typical senescence phenotypes such as diminished stemness and osteogenic capacity, increased expression of senescence or osteoclastic markers and enhanced adipogenic potential. These phenotypic changes are a result of SATB2-mediated senescence dysregulation as evidenced by nuclear γH2AX foci formation. Moreover, overexpression of SATB2 significantly alleviated the senescence of osteoporotic BMSCs in vitro. Importantly, transplantation of SATB2-modified BMSCs significantly attenuated ovariectomy-induced alveolar bone loss in vivo. Together, our results revealed that SATB2 is a critical regulator of alveolar BMSC senescence, and its overexpression decreases these senescent changes both in vitro and in vivo. SATB2-modified BMSC delivery could be a viable and promising therapeutic strategy for alveolar bone loss induced by estrogen-deficient osteoporosis.

Relation between osteoporosis and radiographic and clinical signs of osteoarthritis/arthrosis in the temporomandibular joint: a population-based, cross-sectional study in an older Swedish population

OBJECTIVE

The aim was to elucidate the relation between osteoporosis and osteoarthritis/arthrosis (OA) in the temporomandibular joint (TMJ).

BACKGROUND

General epidemiological data support the hypothesis that osteoporosis and OA are inversely correlated but is not conclusively investigated in the TMJ.

MATERIALS AND METHODS

A group of 114 representative elderly women and men, randomised from a comprehensive population study in Gothenburg, Sweden, had bone mineral density established with whole-body, dual-energy X-ray absorptiometry (DXA) as part of a health survey. In addition, dental examinations were performed, including panoramic radiographs exposed as an overview of the TMJ's and jaws. In 88 of the 80-year-old participants (48 women and 40 men), a clinical orofacial examination according to the RDC/TMD system was performed.

RESULTS

A diagnosis of osteopenia/osteoporosis was found in 36% of the 114, with a statistically different greater proportion of women. Condylar alterations evaluated from panoramic radiographs were observed in 34%, with no significant gender difference. No significant differences were found in the proportion of individuals with osteopenia/osteoporosis and any condylar radiographic alteration or not. Forty-one of the clinically examined subjects, 47%, fulfilled the criteria for an RDC/TMD diagnosis with no gender difference. All participants graded the orofacial pain as low chronic pain. An opening capacity of <40 mm denoted a higher risk of having pain in the temporomandibular system. No association was found between clinical diagnosis of RDC/TMD and osteopenia/osteoporosis.

CONCLUSION

The prevalence of osteopenia/osteoporosis appears not to be of importance for radiological or clinical findings of OA in the TMJ.

Factors associated with having less than 20 natural teeth in rural adults: a cross-sectional study

BACKGROUND

Some systematic reviews have consistently indicated a positive link between Metabolic syndrome, impairedfasting glucose, all-cause or circulatory disease-related mortality, general health, periodontitis, and toothloss. This study was to examine the prevalence of number of remaining teeth <20 and associated risk factors among adults in a rural area of Taiwan.

METHODS

A community-based, cross-sectional study was conducted in southwestern coastal Taiwan in 2013; 6680 residents aged 20-64 years were studied. Oral hygiene, substance use, dietary habits, and metabolic syndrome were explored as potential risk factors for number of remaining teeth <20 using logistic regression analysis.

RESULTS

The mean number of remaining teeth was 24.6 (SD = 7.4), and 16.3 % (n = 1085) of the participants had number of remaining teeth <20. Men had significantly less frequent use of dental floss, unhealthy dietary habits, more substance use and metabolic syndrome than did women (p <0.001). However, women tended to have fewer teeth than men (p <0.001). After adjusting for potential confounders, older age (odds ratio [OR] = 4.56, 95 % confidence interval [CI]: 3.74-5.55), female (OR = 1.88, 95 % CI: 1.56-2.25), less education (OR = 2.40, 95 % CI: 1.90-3.02), infrequent use of dental floss (OR = 1.94, 95 % CI: 1.66-2.27), substance use (OR = 1.32, 95 % CI: 1.09-1.59), and number of metabolic syndrome components (OR = 1.10, 95 % CI: 1.04-1.16) were independently associated with a higher risk of number of remaining teeth <20.

CONCLUSIONS

Number of remaining teeth <20 was highly prevalent among rural adults. In addition to unmodifiable factors, infrequent use of dental floss, substance use, and metabolic syndrome were risk factors associated with tooth loss.

Effects of occlusion on mandibular morphology and architecture in rats

BACKGROUND

A rodent occlusal hypofunction model has been widely established in jawbone-related studies. However, the effects of occlusal stimuli, with total elimination of molar contacts, and its rehabilitation on mandibular remodeling remain unclear.

MATERIALS AND METHODS

Forty-eight 5-wk-old Sprague-Dawley male rats were used. Twenty-four experimental rats underwent occlusal hypofunction by insertion of a bite-raising appliance. Twenty-four rats received no treatment (control group). Two weeks later, half the experimental rats (occlusal hypofunction group) were killed; the appliance was removed from the remaining experimental rats (recovery group) for two additional weeks before killing. Control animals were killed biweekly. Body weight and masseter muscle weight were measured, and the mandibles were subjected to micro-computed tomography to evaluate the mandibular morphology and cortical bone characteristics. The expressions of osteoblast- and osteoclast-related genes were evaluated with quantitative polymerase chain reaction.

RESULTS

No significant body weight differences were observed between the experimental and control rats. However, lighter masseter muscle, shorter mandibular incisor crown, mandibular body and ramus, and higher mandibular alveolar process and first molar fossae were observed in the occlusal hypofunction group. Moreover, the cortical bone characteristics associated with the expression of osteoblast- and osteoclast-related genes were remarkably different in the central and posterior mandible in the occlusal hypofunction group. At the 2-wk recovery time point after occlusal stimuli, the altered parameters in the masseter and mandible returned to normal levels.

CONCLUSIONS

Mandibular remodeling via bone turnover is region specific for altered occlusal stimuli. Normal occlusion is an important determinant of the mandibular morphology and architecture.

Association between adult height and tooth loss in a representative sample of Koreans

OBJECTIVES

Evidence suggests that taller individuals have better health than that of shorter individuals. However, evidence for links to tooth loss is scarce. The aim of this study was to examine the association between adult height and tooth loss and to examine the roles of covariates in explaining the association in different birth cohorts in Korea.

METHODS

Using data from the Fourth and Fifth Korea National Health and Nutritional Examination Survey (KNHANES IV and V), the subjects were grouped into two birth cohorts based on their historical context: born from 1920 to 1945 and 1946 to 1962. The dependent variables were loss of 8 or more teeth and total tooth loss (edentulism), while the independent variable was the height quartile. Demographic factors (survey year, age, and gender), early childhood/adult socioeconomic status (SES) (father's education, own education, income, and place of residence), health behaviors (cigarette smoking, binge drinking, frequency of toothbrushing, and regular dental visit), and health problems (diabetes and hypertension) were included in a series of analytical models.

RESULTS

The survey year-, age-, and gender-adjusted prevalence ratios (PR) of the loss of 8 or more teeth for the shortest quartile were 1.23 (95% confidence intervals, CI: 1.13-1.35) for the 1920-1945 birth cohorts and 1.39 (95% CI: 1.20-1.62) for the 1946-1962 birth cohorts. The PRs for edentulousness were 1.64 (95% CI: 1.34-2.02) for the 1920-1945 birth cohorts and 2.26 (95% CI: 1.31-3.91) for the 1946-1962 birth cohorts. These associations were moderately attenuated after adjusting for own education but still significant in the fully adjusted models. After full adjustment for the covariates, those in the shortest height quartiles in the relatively young birth cohorts (1946-1962 birth cohorts) had a 1.93 (95% CI: 1.09-3.43) times greater prevalence of edentulism than that of their tallest counterparts.

CONCLUSIONS

Given that adult height reflects early-life conditions, independent associations between height and tooth loss support the view that early-life circumstances significantly influence oral health outcomes in later life.

The ovariectomized rat as a model for studying alveolar bone loss in postmenopausal women

In postmenopausal women, reduced bone mineral density at the hip and spine is associated with an increased risk of tooth loss, possibly due to a loss of alveolar bone. In turn, having fewer natural teeth may lead to compromised food choices resulting in a poor diet that can contribute to chronic disease risk. The tight link between alveolar bone preservation, tooth retention, better nutritional status, and reduced risk of developing a chronic disease begins with the mitigation of postmenopausal bone loss. The ovariectomized rat, a widely used preclinical model for studying postmenopausal bone loss that mimics deterioration of bone tissue in the hip and spine, can also be used to study mineral and structural changes in alveolar bone to develop drug and/or dietary strategies aimed at tooth retention. This review discusses key findings from studies investigating mandible health and alveolar bone in the ovariectomized rat model. Considerations to maximize the benefits of this model are also included. These include the measurement techniques used, the age at ovariectomy, the duration that a rat is studied after ovariectomy and habitual diet consumed.

Tooth loss early in life accelerates age-related bone deterioration in mice

Both osteoporosis and tooth loss are health concerns that affect many older people. Osteoporosis is a common skeletal disease of the elderly, characterized by low bone mass and microstructural deterioration of bone tissue. Chronic mild stress is a risk factor for osteoporosis. Many studies showed that tooth loss induced neurological alterations through activation of a stress hormone, corticosterone, in mice. In this study, we tested the hypothesis that tooth loss early in life may accelerate age-related bone deterioration using a mouse model. Male senescence-accelerated mouse strain P8 (SAMP8) mice were randomly divided into control and toothless groups. Removal of the upper molar teeth was performed at one month of age. Bone response was evaluated at 2, 5 and 9 months of age. Tooth loss early in life caused a significant increase in circulating corticosterone level with age. Osteoblast bone formation was suppressed and osteoclast bone resorption was activated in the toothless mice. Trabecular bone volume fraction of the vertebra and femur was decreased in the toothless mice with age. The bone quality was reduced in the toothless mice at 5 and 9 months of age, compared with the age-matched control mice. These findings indicate that tooth loss early in life impairs the dynamic homeostasis of the bone formation and bone resorption, leading to reduced bone strength with age. Long-term tooth loss may have a cumulative detrimental effect on bone health. It is important to take appropriate measures to treat tooth loss in older people for preventing and/or treating senile osteoporosis.

Estrogen Deficiency-Associated Bone Loss in the Maxilla: A Methodology to Quantify the Changes in the Maxillary Intra-radicular Alveolar Bone in an Ovariectomized Rat Osteoporosis Model

The effects of estrogen deficiency on bone characteristics are site-dependent, with the most commonly studied sites being appendicular long bones (proximal femur and tibia) and axial bones (vertebra). The effect on the maxillary and mandibular bones is still inconsistent and requires further investigation. This study was designed to evaluate bone quality in the posterior maxilla of ovariectomized rats to validate this site as an appropriate model to study the effect of osteoporotic changes. Forty-eight 3-month-old female Sprague-Dawley rats were randomly divided into two groups: an ovariectomized (OVX) group (n=24) and Sham-operated (SHAM) group (n=24). Six rats were randomly sacrificed from both groups at time points 8, 12, 16, and 20 weeks. The samples from tibia and maxilla were collected for micro computed tomography (μCT) and histological analysis. For the maxilla, the volume of interest area focused on the furcation areas of the first and second molar. Trabecular bone volume fraction (BV/TV, %), trabecular thickness (Tb.Th.), trabecular number (Tb.N.), trabecular separation (Tb.Sp.), and connectivity density (Conn.Dens) were analyzed after Micro CT scanning. At 8 weeks the indices BV/TV, Tb.Sp., Tb.N., and Conn.Dens showed significant differences (p<0.05) between the OVX and SHAM groups in the tibia. Compared with the tibia, the maxilla developed osteoporosis at a later stage, with significant changes in maxillary bone density only occurring after 12 weeks. Compared with the SHAM group, both the first and second molars of the OVX group showed significantly decreased BV/TV values from 12 weeks, and these changes were sustained through 16 and 20 weeks. For Tb.Sp., there were significant increases in bone values for the OVX group compared with the SHAM group at 12, 16, and 20 weeks. Histological changes were highly consistent with Micro CT results. This study established a method to quantify the changes of intra-radicular alveolar bone in the posterior maxilla in an accepted rat osteoporosis model. The degree of the osteoporotic changes to trabecular bone architecture is site-dependent and at least 3 months are required for the osteoporotic effects to be apparent in the posterior maxilla following rat OVX.

Identifying dental panoramic radiograph features for the screening of low bone mass in postmenopausal women

A retrospective cohort study was performed to evaluate the use of panoramic radiographs as a screening tool for low bone mass in postmenopausal women. Female subjects aged ≥50 years were included. The predictor variables were gonial angle, antegonial angle, mandibular cortical bone integrity, periodontal disease status, and number of remaining teeth. The primary outcome variable was bone mineral density status. Descriptive and logistic regression statistics were computed; P<0.05 was considered significant. The sample was composed of 273 subjects, aged 50-89 years. Visual assessment of mandibular cortical bone integrity demonstrated a statistically significant correlation with low bone mass diagnosis on univariate logistic regression (P=0.019), but lost significance on multivariate analysis with age, body mass index, and number of remaining teeth (P=0.6). A visual estimation of the mandibular cortical bone integrity from panoramic radiographs may be useful for identifying postmenopausal women at high risk for osteoporosis.

Osteopenic consequences of botulinum toxin injections in the masticatory muscles: a pilot study

Patients with temporomandibular muscle and joint disorder (TMJD) increasingly seek and receive treatment for their pain with botulinum toxin (BoNTA; botulinum toxin A). Used intramuscularly in therapeutic doses, it produces localised paresis. Such paresis creates risk of reduced bone mineral density, or 'disuse osteopenia'. Animal studies have frequently used BoNTA as a model of paralysis to induce bone changes within short periods. Osteopenic effects can be enduring in animals but have yet to be studied in humans. This is the first study in humans to examine bone-related consequences of BoNTA injections in the masticatory muscles, comparing oral and maxillofacial radiologists' ratings of trabecular bone patterns in the condyles of patients with TMJD exposed to multiple masticatory muscle injection sessions with BoNTA to a sample of patients with TMJD unexposed to masticatory muscle injections with BoNTA. Cone-beam computed tomography (CBCT)-derived images of bilateral condyles were evaluated in seven patients with TMJD receiving 2+ recent BoNTA treatment sessions for facial pain and nine demographically matched patients with TMJD not receiving BoNTA treatment. Two oral and maxillofacial radiologists evaluated CBCT images for evidence of trabecular changes consistent with osteopenia. Both evaluators noted decreased density in all participants exposed to BoNTA and in none of the unexposed participants (P < 0.001). No other abnormalities associated with reduced loading were detected. These findings need replication in a larger sample and over a longer time period, to ensure safety of patients with TMJD receiving multiple BoNTA injections for their pain.