The effect of diabetes mellitus on rat mandibular bone formation and microarchitecture

Hyperbaric oxygen therapy exerts anti-osteoporotic effects in obese and lean D-galactose-induced aged rats

Obesity accelerates the aging processes, resulting in an aggravation of aging-induced osteoporosis. We investigated the anti-osteoporotic effect of hyperbaric oxygen therapy (HBOT) in obese- and lean-aged rats through measurement of cellular senescence, hypoxia, inflammation, antioxidants, and bone microarchitecture. Obese and lean male Wistar rats were injected with 150 mg/kg/day of D-galactose for 8 weeks to induce aging. Then, all rats were randomly given either sham or HBOT for 14 days. Metabolic parameters were determined. Expression by bone mRNA for cellular senescence, hypoxia, inflammation, antioxidative capacity, and bone remodeling were examined. Micro-computed tomography and atomic absorption spectroscopy were performed to evaluate bone microarchitecture and bone mineral profiles, respectively. We found that HBOT restored the alterations in the mRNA expression level of p16, p21, HIF-1α, TNF-α, IL-6, RANKL, RANK, NFATc1, DC-STAMP, Osx, ALP, and Col1a1 in the bone in obese-and lean- aging rats. In obese-aging rats, HBOT increased the level of expression of Sirt1 and CuZnSOD mRNA and diminished the expression level of HIF-2α and ctsk mRNA to the same levels as the control group. However, HBOT failed to alter catalase and OCN mRNA expression in obese-aged rats. HBOT partially improved the bone microarchitecture in obese-aged rats, but completely restored it in lean-aged rats. Interestingly, HBOT protected against obesity-induced demineralization in obese-aged rats. In summary, HBOT exerts an anti-osteoporotic effect in lean-aged rats and prevents some, but not all the negative effects of obese-aged conditions on bone health. Therefore, HBOT is considered as a potential therapy for aging-induced osteoporosis, regardless of obese status.

The onset of adenosine monophosphate-activated protein kinase activity on orthodontic tooth movement in rats with type 2 diabetes

Adenosine monophosphate-activated protein kinase (AMPK) plays pivotal roles in metabolic diseases including type 2 diabetes. However, the specific role of AMPK for orthodontic tooth movement in type 2 diabetes is unclear. In this study, a diabetic rat model was established through dietary manipulation and streptozocin injection. Examinations were conducted to select qualified type 2 diabetic rats. Then, an orthodontic device was applied to these rats for 0, 3, 7, or 14 days. The distance of orthodontic tooth movement and parameters of alveolar bone were analyzed by micro-computed tomography. Periodontal osteoclastic activity, inflammatory status, and AMPK activity were measured via histological analyses. Next, we repeated the establishment of diabetic rats to investigate whether change of AMPK activity was associated with orthodontic tooth movement under type 2 diabetes. The results showed that diabetic rats exhibited an exacerbated alveolar bone resorption, overactive inflammation, and decreased periodontal AMPK activity during orthodontic tooth movement. Injection of the AMPK agonist alleviated type 2 diabetes-induced periodontal inflammation and alveolar bone resorption, thus normalizing distance of orthodontic tooth movement. Our study indicates that type 2 diabetes decreases periodontal AMPK activity, leading to excessive inflammation elevating osteoclast formation and alveolar bone resorption, which could be reversed by AMPK activation.

Molar-incisor hypomineralisation prevalence in a cohort of Australian children with type 1 diabetes

PURPOSE

Systemic diseases or drugs administered early in life may cause a disruption in amelogenesis and contribute to the qualitative defect of enamel described as molar-incisor hypomineralisation (MIH). Therefore, an increase in prevalence of MIH in children with type 1 diabetes (T1D) may be expected as this systemic disorder is commonly diagnosed in early childhood. The aim of this study was to determine the prevalence of MIH in a cohort of children with T1D and investigate diagnosis of MIH with T1D factors.

METHODS

Cross-sectional study of children with T1D recruited from paediatric diabetes clinics at the Women's and Children's Hospital (South Australia). A detailed medical history, comprehensive dental and MIH examination according to the European Academy of Paediatric Dentistry (EAPD) long form classification was collected for each child. All upper and lower first permanent molars and central incisors were scored.

RESULTS

A total number of 73 participants; 35 (47.95%) males were examined including 584 teeth. The mean age of the participants was 13.25 ± 2.58 years, with a mean age of diagnosis 7.75 ± 3.58 years, and a mean HbA1c of 8.5 ± 1.6%. 42 out of 73 children (54.8%) had enamel defects on at least one of the teeth examined. However, 19.2% met the criteria for MIH. Univariate and bivariate analyses were conducted but no significant associations were noted between MIH and risk factors including diabetes control (p > 0.1).

CONCLUSION

There was a high prevalence of enamel defects and MIH amongst children with T1D. More research is required to establish association between T1D and MIH.

Osteoprotective Effects of ‘Anti-Diabetic’ Polyherbal Mixture in Type 1 Diabetic Rats

Bone loss leading to osteopenia and osteoporosis is a frequent secondary complication of diabetes. This study aimed to evaluate the value of a traditionally used ‘anti-diabetic’ polyherbal mixture as a possible remedy for the prevention of this complication. Diabetes was induced in Wistar female rats with a single intraperitoneal injection of alloxan monohydrate. The animals with blood glucose higher than 20 mmol/L for 14 consecutive days were considered diabetic. For the next 14 days, animals were treated with two concentrations of the polyherbal mixture (10 and 20 g of dry plant material/ kg). Bone histopathology was evaluated using the H&E and Masson’s trichrome staining. Alloxan-induced diabetes triggered bone histological changes characteristic for the development of osteopenia and osteoporosis and treatment with the polyherbal decoction restored these histopathological changes of the bones to the healthy animal level. At the same time, treatment with these tested doses has shown no adverse effects. These findings suggest that this mixture might be used as a remedy for the prevention of diabetic bone loss.

Osteopenic effects of high-fat diet-induced obesity on mechanically induced alveolar bone remodeling

OBJECTIVES

The aim of the study was to investigate the effect of obesity on the tissue and molecular reactions of alveolar bone in response to orthodontic force and its underlying mechanisms.

METHODS

Sixty-four rats were randomly divided into normal diet (ND) and high-fat diet (HFD) groups for eight weeks of dietary treatment. OTM was induced using nickel-titanium springs between the upper left first molar and incisor. After 1, 3, 7, and 14 days of OTM, the maxillary alveolar bone and gingival tissues were harvested and analyzed.

RESULTS

Compared with the ND rats, the HFD rats had greater OTM distance, serum levels of tartrate-resistant acid phosphatase (TRAP), and tumor necrosis factor α (TNF-α), as well as significant alveolar bone loss and bone architecture deterioration on both the compression and tension sides (p < .05 for all). This response was linked to the increased osteoclast numbers and functional activity and decreased osteoblast activity in the periodontal ligament, gingival tissue, and alveolar bone.

CONCLUSIONS

HFD-induced obesity promoted mechanically induced alveolar bone remodeling and detrimental changes in alveolar bone microstructure by increasing osteoclastogenesis and regulating inflammatory cytokine expression. The increased alveolar bone remodeling in the obese rats lead to an accelerated OTM.

The Impact of Curcumin on Bone Osteogenic Promotion of MC3T3 Cells under High Glucose Conditions and Enhanced Bone Formation in Diabetic Mice

Diabetic osteoporosis (DOP) is characterized by impaired bone microstructure and reduced bone density resulting from high glucose levels. Curcumin (CURC) is extensively applied in the treatment of inflammation-associated diseases. However, the effect of curcumin on bone metabolism in diabetic osteoporosis is unclear. Therefore, this study investigated the optimal concentration of curcumin on enhancing osteogenesis in diabetic osteoporosis. Osteoblasts were treated with a high or low concentration of curcumin under a series of concentrations of high-glucose conditions. Type 2 diabetic mice were intervened with curcumin. Cell proliferation, apoptosis, and osteogenesis-related gene expressions were evaluated by CCK-8, flow cytometry, and real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Bone formation was evaluated by histological staining. The findings revealed that curcumin suppressed apoptosis and enhanced proliferation and osteogenesis-related gene expressions of osteoblasts under high glucose concentrations (p < 0.05). The histological sections displayed reduced bone destruction and increased the growth rate of trabecular bone and the bone density of diabetic mice treated with curcumin, compared to diabetic mice. These results showed that curcumin could reverse the harmful effects of diabetic osteoporosis in a dose-dependent manner, and 10 μmol/L was regarded as the optimal concentration, which supports the potential use of curcumin for bone regeneration under high glucose concentrations.

Cyclosporine A impairs bone repair in critical defects filled with different osteoconductive bone substitutes

The aim of this study was to assess the influence of cyclosporine administration on the repair of critical-sized calvaria defects (CSDs) in rat calvaria filled with diverse biomaterials. Sixty animals were divided into two groups: the control (CTR) group (saline solution) and the cyclosporine (CCP) group (cyclosporine, 10 mg/kg/day). These medications were administered daily by gavage, beginning 15 days before the surgical procedure and lasting until the day the animals were euthanized. A CSD (5 mm Ø) was made in the calvaria of each animal, which was allocated to one of 3 subgroups, according to the biomaterial used to fill the defect: coagulum (COA), deproteinized bovine bone (DBB), or biphasic calcium phosphate ceramics of hydroxyapatite and β-phosphate tricalcium (HA/TCP). Euthanasia of the animals was performed 15 and 60 days after the surgical procedure (n = 5 animals/period/subgroup). Bone repair (formation) assessment was performed through microtomography and histometry, while the analyses of the expression of the BMP2, Osteocalcin, and TGFβ1 proteins were performed using immunohistochemistry. The CSDs not filled with biomaterials demonstrated lower bone formation in the CCP group. At 15 days, less bone formation was observed in the CSDs filled with DBB, a smaller volume of mineralized tissue was observed in the CSDs filled with HA/TCP, and the expression levels of BMP2 and osteocalcin were lower in the CCP group compared to the CTR group. The use of cyclosporine impaired bone repair in CSD, and this effect can be partially explained by the suppression of BMP2 and osteocalcin expression.

Altered gut microbiota ameliorates bone pathology in the mandible of obese-insulin-resistant rats

PURPOSE

The chronic consumption of a high-fat diet (HFD) induces obese-insulin resistance and impairs jawbone health via gut dysbiosis-stimulated inflammatory process. Our previous studies demonstrated that the probiotic Lactobacillus paracasei HII01, prebiotic xylooligosaccharide (XOS), and synbiotics improved several vital organ functions by reducing gut dysbiosis in HFD-induced obese rats. However, the impacts on the cellular level of jawbone microarchitecture have not been examined. Here, we hypothesized that the supplementation of L. paracasei HII01, XOS, and synbiotics ameliorated the bone microarchitectural pathology in HFD-fed rats by reducing systemic inflammation and other metabolic parameters.

METHODS

The dietary regimes (normal or high-fat diet) were provided to 48 male Wistar rats throughout 24-week experiment. After week 12, rats were given either a vehicle, pro-, pre-, or synbiotic for an additional 12 weeks before being killed. Then, blood analyses and bone histomorphometry of the jawbones were performed.

RESULTS

The HFD-fed rats developed obese-insulin resistance with significantly elevated systemic inflammation. Bone histomorphometry of these rats showed a decrease in trabecular thickness with increased osteoclasts and active erosion surfaces. Mineral apposition and bone-formation rates were also remarkably diminished. The treatment with pro-, pre-, and synbiotics equally improved metabolic disturbance, reduced systemic inflammation, increased trabecular thickness, decreased osteoclasts and active erosion surfaces and restored mineral apposition and bone-formation rates.

CONCLUSION

The probiotic L. paracasei HII01, prebiotic XOS, and the synbiotics had similarly beneficial effects to improve jawbone microarchitecture in HFD-fed rats by possibly ameliorating osteoclast-related bone resorption and potentiating bone-formation activities.

Metformin as an add-on to insulin improves periodontal response during orthodontic tooth movement in type 1 diabetic rats

BACKGROUND

Type 1 diabetes (T1D) is associated with delayed tissue healing and bone loss. Periodontal tissues during tooth movement (OTM) in T1D and under diabetic treatment are poorly understood. We aimed to study the effect of metformin as an add-on to insulin therapy on periodontal structures during OTM in T1D rats.

METHODS

Rats were divided into normoglycemic (NG, n = 20) and streptozotocin-induced diabetic groups that were untreated (T1D, n = 20), treated with insulin (I-T1D, n = 20), or treated with insulin plus metformin (IM-T1D, n = 20). After 7 days of treatment, the first right upper molar (M1) was moved mesially. At days 0, 3, 7 and 14, the pattern of OTM and the periodontal tissues were analyzed by micro-CT, histomorphometry, and immunohistochemistry for TRAP.

RESULTS

In T1D, major osteoclastogenic activity and bone loss versus other groups were confirmed by a greater TRAP-positive cell number and reabsorption surface on both the pressure and tension sides for 14 days (p < 0.01). Additionally, we observed low bone volume density. Metformin plus insulin resulted in a daily insulin dose reduction and major glycemic control versus I-T1D. Although no significant differences were observed between I-T1D and IM-T1D, the tooth displacement and inclination, periodontal ligament thickness, and alveolar bone density on the pressure side in IM-T1D were similar to that of NG (p > 0.05).

CONCLUSION

Antidiabetic treatment reduces severe periodontal damage during applied orthodontic force in T1D untreated rats. Metformin as an add-on to insulin therapy resulted in glycemic control and a periodontal tissue response to orthodontic forces that was similar to that of normoglycemic rats.

In Silico Interaction of the Active Compounds of Scurrula Atropurpurea with the RANK/RANKL/OPG System in Diabetoporosis

Introduction:

Diabetoporosis is a very complex health problem in Indonesia. One approach to the problem is through native Indonesian herbal medicine. The application of Scurrula atropurpurea in the treatment of diabetoporosis has not been revealed, so preliminary in silico study needs to be done.

Aim:

The purpose of the present study was to analyze the interaction between the active compound of Scurrula atropurpurea and the RANKL/RANK/OPG system in the pathomechanism of osteoporosis in diabetes mellitus.

Methods:

The procedures of the study included the search for the constituent amino acid of the RANK/RANKL/OPG system, the search for the structure of the active component of Scurrula atropurpurea, 3D modeling of protein structure, protein-ligand docking and visualization, and analysis of protein-ligand bonding interactions.

Results:

Those bond energies were RANKL-aviculin (–274.96 kJ/mol), RANKL-rutin (–263.12 kJ/mol), RANKL-quercitrin (–256.98 kJ/mol), RANKL-quercetin (–226,50 kJ/mol), RANKL-kaempferol (–221,65 kJ/mol), RANKL-catechin (–214,85 kJ/mol), RANKL-epicatechin (–211.66 kJ/mol), RANKL-caffeine (-171.73 kJ/mol), and RANKL-theobromine (-161.14 kJ/mol). The bond energies were RANK-rutin (-719.26 kJ/mol), RANK-catechin (-680.15 kJ/mol), RANK-caffeine (-654.48 kJ/mol), RANK-theobromine (-651.77 kJ/mol), RANK-quercitrin (-650.68 kJ/mol), RANK-kaempferol (-643.03 kJ/mol), RANK-epicatechin (-641.86 kJ/mol), RANK-quercetin (-641.76 kJ/mol), and RANK-aviculin (-628.62 kJ/mol). Those bond energies were OPG-epicatechin (-590.09 kJ/mol), OPG-theobromine (-578.08 kJ/mol), OPG-caffeine (-568.88 kJ/mol), RANKL-catechin (-560.63 kJ/mol), OPG-quercitrin (-554.50 kJ/mol), OPG-rutin (-547.91 kJ/mol), OPG-quercetin (-545.75 kJ/mol), OPG-kaempferol (-544.48 kJ/mol), and OPG-aviculin (-539.15 kJ/mol).

Conclusion:

The nine active ingredients of Scurrula atropurpurea do not interfere with the physiological function of RANKL to interact with RANK. The initial interaction of RANK with catechin or rutin will facilitate the bond of RANK to RANKL. When forming a complex with OPG, epicatechin will facilitate its interaction with RANKL.

Effect of a bisphosphonate and selective estrogen receptor modulator on bone remodeling in streptozotocin-induced diabetes and ovariectomized rat model

BACKGROUND CONTEXT

Diabetes and menopause can cause severe osteoporosis. In general, menopause and diabetes can lead to an imbalance in bone turnover, which results in secondary osteoporosis. However, the efficacy of antiresorptive drugs against this form of osteoporosis has not been extensively evaluated.

OBJECTIVE

The aim of this study was to determine the changes in vertebral bone remodeling when postmenopausal osteoporosis is accompanied by diabetes and to compare the efficacy of bisphosphonates and selective estrogen-receptor modulators (SERMs) against these outcomes.

STUDY DESIGN

Streptozotocin-induced diabetic, ovariectomized Sprague-Dawley rats were used as the disease model. Alendronate and raloxifene were used as the bisphosphonate and SERM, respectively.

METHODS

We divided 62 female rats into five groups: (1) control (n=14), (2) DM (diabetes) (n=12), (3) DM+OVX (diabetes+ovariectomy) (n=12), (4) DM+OVX+A (diabetes+ovariectomy+alendronate) (n=12), and (5) DM+OVX+R (diabetes+ovariectomy+raloxifene) (n=12). Serum biochemical markers of bone turnover, including osteocalcin and the C-telopeptide of type I collagen (CTX-1), were analyzed. We measured histomorphometric parameters of the fourth lumbar vertebrae using microcomputed tomography. Mechanical strength was evaluated by a compression test.

RESULTS

In the DM and DM+OVX group, only the levels of osteocalcin significantly decreased compared with those of the control group at 8 weeks after OVX. At 12 weeks, the serum CTX-1 levels in the DM+OVX+A and DM+OVX+R groups were significantly lower than those of the DM+OVX group, but there were no changes in the levels of osteocalcin. Bone mineral density and mechanical strength were higher in the DM+OVX+A and DM+OVX+R groups than in the DM and DM+OVX groups (p<.05).

CONCLUSIONS

Even if postmenopausal osteoporosis is accompanied by diabetes in this animal model, both alendronate and raloxifene seem to show antiresorptive effects, decreased bone turnover rates, and improved bone mechanical strength. Therefore, alendronate and raloxifene are effective in the treatment of osteoporosis even for bone loss caused by DM and postmenopausal osteoporosis.

Assessment of bone quality in patients with diabetes mellitus

Substantial evidence exists that diabetes mellitus is associated with an increased risk of osteoporotic fractures. Low bone strength as well as bone extrinsic factors are probably contributing to the increased bone fragility in diabetes. Bone density and quality are important determinants of bone strength. Although bone mineral density (BMD) and the fracture risk assessment tool (FRAX) are very useful clinical tools in assessing bone strength, they may underestimate the fracture risk in diabetes mellitus. Through advances in new technologies such as trabecular bone score (TBS) and peripheral quantitative computed tomography (pQCT), we can better assess the bone quality and fracture risk of patients with diabetes mellitus. Invasive assessments such as microindentation and histomorphometry have been great complement to the existing bone analysis techniques. Bone turnover markers have been found to be altered in diabetes mellitus patients and may be associated with fractures. This review will give a brief summary of the current development and clinical uses of these assessments.

Glycemic control protects against trabecular bone microarchitectural damage in a juvenile male rat model of streptozotocin-induced diabetes

PURPOSE

To determine which features of the bone microarchitecture are affected by established diabetes mellitus (DM) and the effectiveness of glycemic control in the protection of bone tissue.

MATERIAL AND METHODS

Sixty juvenile Wistar male rats were divided into three groups of 20 animals: a control group (C) that included healthy animals, a diabetic group (D) that included animals with induced diabetes, and a controlled diabetic group (CD) that included animals with induced diabetes that were treated with insulin. The animals were euthanized at the periods of 6 and 8 weeks after the induction of diabetes (10 animals per group/period). Vertebral L4 specimens were submitted to μCT analysis to assess the following parameters of the bone microarchitecture: bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular spacing (Tb.Sp).

RESULTS

The D group exhibited lower values of BV/TV (%) and numbers of trabeculae compared with the C group at 6 and 8 weeks and compared with the CD group at 8 weeks. The CD group exhibited higher trabecular thickness values compared with the D group at 8 weeks. There were no differences between the groups regarding the spaces between the trabeculae.

CONCLUSION

Induced diabetes affected the microarchitecture of the trabecular bone of the vertebrae by reducing the values of the majority of the parameters in relation to those of the control group. Glycemic control with insulin appears to protect bones from the effects of the hyperglycemia.

The effects of low-level laser therapy on the healing of bone defects in streptozotocin-induced diabetic rats: A histological and morphometric evaluation

BACKGROUND

The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) on the healing of bone defects in rats with streptozotocin (STZ)-induced DM.

METHODS

28 male Sprague-Dawley rats were used in this study. 14 animals received a single dose of STZ intraperitoneally (65 mg/kg) to induce Type I DM, whereas others were injected only with sterile saline solution. Four weeks later, standard bone defects were created in the tibiae of rats. Surgical wounds in one group from each of the diabetic and non-diabetic animals were irradiated with diode laser for every other day for 4 weeks and they were described as DM + LLLT and CONT + LLLT groups, respectively. Remaining two groups received no laser treatment. New bone formation, osteoblast and blood vessel counts were calculated in histologic sections.

RESULTS

DM group had significantly smaller bone area and lower blood vessel count when compared to DM + LLLT, CONT and CONT + LLLT groups (p < 0.05 for each). CONT and CONT + LLLT groups had significantly larger bone area than DM + LLLT group (p < 0.05 for both).

CONCLUSIONS

LLLT application promoted vascularization and new bone formation in animals with DM to a limited extent, since it was unable to support the healing process up to the level of non-diabetic animals.

Survival/Success of Dental Implants with Acid-Etched Surfaces: A Retrospective Evaluation After 8 to 10 Years

Abstract The aim of this study was to conduct a retrospective evaluation of the survival and success rates of dental implants with acid-etched surfaces after 8-10 years of function. Forty-four patients who received 183 implants 8-10 years ago were evaluated. Clinical examinations were performed around the implants and natural teeth. The following parameters were measured: visible plaque index (VPI), marginal bleeding index (MBI), probing depth (PD), bleeding on probing (BOP) and clinical attachment level (CAL). To considerer an implant as a success case, the following criteria were considered: absence of peri-implant infection and suppuration, absence of implant mobility, absence of persistent pain and dysesthesia and absence of radiolucency around the implant. Overall, 178 implants were categorized as surviving (97.3%), 155 were categorized as successful (84.7%), 5 implants (2.7%) were lost (1 in the maxilla and 4 in the mandible), and 3 implants were not under functional load (2.0 %). 20 implants were diagnosed with peri-implantitis. Thus, the survival rate was 97% and the success rate was 85%. In conclusion, implants with acid-etched surfaces showed high survival and success rates after a period of 8 to 10 years of function.

Does Oxidative Stress Induced by Alcohol Consumption Affect Orthodontic Treatment Outcome?

HIGHLIGHTS Ethanol, Periodontal ligament, Extracellular matrix, Orthodontic movement. Alcohol is a legal drug present in several drinks commonly used worldwide (chemically known as ethyl alcohol or ethanol). Alcohol consumption is associated with several disease conditions, ranging from mental disorders to organic alterations. One of the most deleterious effects of ethanol metabolism is related to oxidative stress. This promotes cellular alterations associated with inflammatory processes that eventually lead to cell death or cell cycle arrest, among others. Alcohol intake leads to bone destruction and modifies the expression of interleukins, metalloproteinases and other pro-inflammatory signals involving GSKβ, Rho, and ERK pathways. Orthodontic treatment implicates mechanical forces on teeth. Interestingly, the extra- and intra-cellular responses of periodontal cells to mechanical movement show a suggestive similarity with the effects induced by ethanol metabolism on bone and other cell types. Several clinical traits such as age, presence of systemic diseases or pharmacological treatments, are taken into account when planning orthodontic treatments. However, little is known about the potential role of the oxidative conditions induced by ethanol intake as a possible setback for orthodontic treatment in adults.

The effects of supplemental melatonin administration on the healing of bone defects in streptozotocin-induced diabetic rats

Diabetes mellitus (DM) causes an increased production of free radicals that can impair bone healing. Melatonin is a hormone secreted mainly by the pineal gland, which participates in the neutralization process of free radicals.

Bone remodeling during orthodontic tooth movement in rats with type 2 diabetes

INTRODUCTION

Type 2 diabetes is known to affect bone metabolism. In this study, we aimed to determine the effects of type 2 diabetes on bone remodeling during orthodontic tooth movement.

METHODS

The 48 rats were divided into 4 groups: Wistar control group (n = 8), Goto-Kakizaki (GK) control group (n = 8), Wistar appliance group (n = 16), and GK appliance group (n = 16). The distances between the teeth were measured weekly. On day 42, maxillary alveolar bone specimens were obtained for histologic evaluation and determination of the gene expression levels of the receptor activator of nuclear factor ҡB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG).

RESULTS

No significant difference was observed in the levels of tooth movement between the 2 appliance groups. After orthodontic force application, the alveolar bone volume and osteoblast surface in the GK rats were diminished compared with those in the Wistar rats. The increase in the osteoclast surface relative to the control groups was 2.4-fold greater in the GK rats than in the Wistar rats. Significant upregulations of the RANK and OPG gene expression levels in the Wistar appliance group were observed. The RANKL/OPG ratio was increased in the GK appliance group compared with the Wistar appliance group.

CONCLUSIONS

Diminished bone formation and slightly increased bone resorption were observed during orthodontic tooth movement in the rats with type 2 diabetes.

Calcitonin and vitamin D3 have high therapeutic potential for improving diabetic mandibular growth

The goal of this study was to assess the effect of the intermittent combination of an antiresorptive agent (calcitonin) and an anabolic agent (vitamin D₃) on treating the detrimental effects of Type 1 diabetes mellitus (DM) on mandibular bone formation and growth. Forty 3-week-old male Wistar rats were divided into four groups: the control group (normal rats), the control C+D group (normal rats injected with calcitonin and vitamin D₃), the diabetic C+D group (diabetic rats injected with calcitonin and vitamin D₃) and the diabetic group (uncontrolled diabetic rats). An experimental DM condition was induced in the male Wistar rats in the diabetic and diabetic C+D groups using a single dose of 60 mg·kg⁻¹ body weight of streptozotocin. Calcitonin and vitamin D₃ were simultaneously injected in the rats of the control C+D and diabetic C+D groups. All rats were killed after 4 weeks, and the right mandibles were evaluated by micro-computed tomography and histomorphometric analysis. Diabetic rats showed a significant deterioration in bone quality and bone formation (diabetic group). By contrast, with the injection of calcitonin and vitamin D₃, both bone parameters and bone formation significantly improved (diabetic C+D group) (P < 0.05). These findings suggest that these two hormones might potentially improve various bone properties.

Intermittent hypoxia induces disturbances in craniofacial growth and defects in craniofacial morphology

OBJECTIVES

To investigate intermittent hypoxia (IH) induced changes in craniofacial morphology and bone mineral density (BMD) in the mandible of growing rats.

DESIGN

Seven-week-old male Sprague-Dawley rats were exposed to IH for 4 days or 3 weeks. Sham-operated rats simultaneously breathed room air. Lateral and transverse cephalometric radiographs of the craniofacial region were obtained, and the linear distances between cephalometric landmarks were statistically analyzed. BMD and bone microstructure of the mandible were evaluated using micro-computed tomography (micro-CT).

RESULTS

Cephalometric analyses demonstrated that exposure to IH only in the two groups for 3 weeks decreased the size of the mandibular and viscerocranial bones, but not that of the neurocranial bones, in early adolescent rats. These findings are consistent with upper airway narrowing and obstructive sleep apnea (OSA). Micro-CT showed that IH increased the BMD in the cancellous bone of the mandibular condyle and the inter-radicular alveolar bone in the mandibular first molar (M1) region.

CONCLUSIONS

This study is the first to identify growth retardation of the craniofacial bones in an animal model of sleep apnea. Notably, 3 weeks of IH can induce multiple changes in the bones around the upper airway in pubertal rats, which can enhance upper airway narrowing and the development of OSA. The reproducibility of these results supports the validity and usefulness of this model. These findings also emphasize the critical importance of morphometric evaluation of patients with OSA.

Management of endocrine disease: Diabetes and osteoporosis: cause for concern?

Diabetes and osteoporosis are both frequent conditions, and they may thus occur simultaneously by chance. However, a growing body of evidence suggests that hyperglycemia may impair bone matrix formation and biochemical competence. Decreased biomechanical competence may be present even in a setting of increased bone mineral density, as assessed by traditional dual energy X-ray absorptiometry or normal structural parameters by quantitative computed tomography. Also, the absence of endogenous insulin secretion in type 1 diabetes (T1D) and insulin resistance or, in some cases, frank hyperinsulinemia in T2D may play a role.

Osteopathology in the Equine Distal Phalanx Associated With the Development and Progression of Laminitis

Although the equine distal phalanx and hoof lamellae are biomechanically and physiologically integrated, bony changes in the distal phalanx are poorly described in laminitis. The aims of this study were (1) to establish a laminitis grading scheme that can be applied to the wide spectrum of lesions seen in naturally occurring cases and (2) to measure and describe changes in the distal phalanx associated with laminitis using micro-computed tomography (micro-CT) and histology. Thirty-six laminitic and normal feet from 15 performance and nonperformance horses were evaluated. A laminitis grading scheme based on radiographic, gross, histopathologic, and temporal parameters was developed. Laminitis severity grades generated by this scheme correlated well with clinical severity and coincided with decreased distal phalanx bone volume and density as measured by micro-CT. Laminitic hoof wall changes included progressive ventral rotation and distal displacement of the distal phalanx with increased thickness of the stratum internum-corium tissues with lamellar wedge formation. Histologically, there was epidermal lamellar necrosis with basement membrane separation and dysplastic regeneration, including acanthosis and hyperkeratosis, corresponding to the lamellar wedge. The changes detected by micro-CT corresponded to microscopic findings in the bone, including osteoclastic osteolysis of trabecular and osteonal bone with medullary inflammation and fibrosis. Bone changes were identified in horses with mild/early stages of laminitis as well as severe/chronic stages. The authors conclude that distal phalangeal pathology is a quantifiable and significant component of laminitis pathology and may have important implications for early detection or therapeutic intervention of equine laminitis.

Diabetes detrimental effects on enamel and dentine formation

OBJECTIVES

Understanding morphological changes and mineral content of tooth hard tissues may influence dental treatment. In this study, the effect of Type 1 Diabetes Mellitus (T1DM) on tooth structure was examined.

METHODS

Experimental T1DM was induced in 3-week old male Wistar rats (n=10) by a single dose of 60mg/kg body weight of Streprozotocin. All rats were injected with calcein twice during the experiment and sacrificed at the age of 7 weeks old. Micro-computed tomography (micro-CT) was used to determine the mineral density and thickness of enamel and dentine. Also, a histomorphometery study was conducted to detect the rates of dentine mineral apposition and formation. The examined area was in the crown analogue of the rat mandibular incisor parallel to the long axis of the mesial surface of the first molar. All results were compared using Students' t-test (p<0.05).

RESULTS

Results showed that the enamel and dentine thickness were significantly reduced (hypoplasia) and there was a significant reduction of the rate of dentine mineral apposition and formation, while there was no significant effect of the T1DM condition on the mineral density of enamel and dentine.

CONCLUSIONS

T1DM has a detrimental influence on the formation of enamel and dentine in the early growth stage.

CLINICAL SIGNIFICANCE

T1DM condition may alter treatment planning of orthodontic treatment as it is associated with decreased enamel and dentin thickness that may affect teeth size and their resistance to caries.

Micro-CT analysis of the rodent jaw bone micro-architecture: A systematic review

Introduction

Knowledge about macro- and micro-structural characteristics may improve in vivo estimation of the quality and quantity of regenerated bone tissue. For this reason, micro-CT imaging has been applied to evaluate alveolar bone remodelling, alterations of periodontal ligament thickness and cortical and trabecular bone changes in rodent jaw bones. In this paper, we provide a systematic review on the available micro-CT literature on jaw bone micro-architecture.

Methodology

A detailed search through the PubMed database was performed. Articles published up to December 2013 and related to maxilla, mandible and condyle with quantitatively analysed bone micro-architectural parameters were considered eligible for inclusion. Two reviewers assessed the search results according to inclusion criteria designed to identify animal studies quantifying the bone micro-architecture of the jaw rodent bones in physiological or drug-induced disease status, or in response to interventions such as mechanical loading, hormonal treatment and other metabolic alterations. Finally, the reporting quality of the included publications was evaluated using the tailored ARRIVE guidelines outlined by Vignoletti and Abrahamsson (2012).

Results

Database search, additional manual searching and assessment of the inclusion and exclusion criteria retrieved 127 potentially relevant articles. Eventually, 14 maxilla, 20 mandible and 12 condyle articles with focus on bone healing were retained, and were analysed together with 3 methodological papers. Each study was described systematically in terms of subject, experimental intervention, follow-up period, selected region of interest used in the micro-CT analysis, parameters quantified, micro-CT scanner device and software. The evidence level evaluated by the ARRIVE guidelines showed high mean scores (between 18 and 25; range: 0–25), indicating that most of the selected studies are well-reported. The major obstacles identified were related to sample size calculation, absence of adverse event descriptions, randomization or blinding procedures.

Conclusions

The evaluated studies are highly heterogeneous in terms of research topic and the different regions of interest. These results illustrate the need for a standardized methodology in micro-CT analysis. While the analysed studies do well according to the ARRIVE guidelines, the micro-CT procedure is often insufficiently described. Therefore we recommend to extend the ARRIVE guidelines for micro-CT studies.

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This review investigates discrepancies between reports using micro-CT imaging of rodent jaw bone, the applied methodology and reported results.

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Knowledge about the bone micro-architecture of the rodent jaw is scarce.

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Jaw bone micro-architecture varies according to ROI selections and the methodology applied to define a specific region are insufficient.

Evaluation of stability of surface-treated mini-implants in diabetic rabbits

Introduction. The purpose of this study was to investigate effects of surface treatment of mini-implants in diabetes-induced rabbits by comparing osseointegration around mini-implants. Methods. Twelve New Zealand white rabbits were divided into two groups (alloxan-induced diabetic group and control group). A total of 48 mini-implants were placed after four weeks of diabetic induction. 24 mini-implants were surface-treated with SLA (sandblasted with large grit, and acid etched) and the remaining 24 mini-implants had smooth surfaces. Four weeks after placement, 32 mini-implants were removed from 4 control and 4 diabetic rabbits. Insertion and removal torques were measured. The remaining 16 mini-implants from the two groups were histomorphometrically analyzed. Results. Maximum insertion torque showed no difference between diabetic and control groups, but total insertion energy was higher in control group. In surface-treated mini-implants, maximum removal torque was higher in both diabetic and control groups. Bone-implant contact (BIC) was increased in the control group when compared to the diabetic group. Surface-treated group had higher BIC than smooth surface group in both control and diabetic groups. However, there was no significantly statistical difference. Conclusions. Type 1 diabetes mellitus and surface treatment method of mini-implant affected primary stability of mini-implants. In addition, the use of orthodontic mini-implants in a diabetic patient is likely to show results similar to the healthy patient.

Decreased jaw bone density and osteoblastic insulin signaling in a model of obesity

Previous studies have demonstrated that decreased bone mass results from either the impairment of osteoblastic insulin signaling or obesity. Our previous study revealed that 12-week high-fat-diet (HFD) consumption caused obesity as well as peripheral and brain insulin resistance. However, the osteoblastic insulin resistance induced by HFD has not been elucidated. Therefore, we hypothesized that 12-week HFD rats exhibited not only peripheral insulin resistance but also osteoblastic insulin resistance, which leads to decreased jawbone quality. We found that the jawbones of rats fed a 12-week HFD exhibited increased osteoporosis. The osteoblastic cells isolated from HFD-fed rats exhibited the impairment of osteoblastic insulin signaling as well as reduction of cell proliferation and survival. In conclusion, this study demonstrated that insulin resistance induced by 12-week HFD impaired osteoblastic insulin signaling, osteoblast proliferation, and osteoblast survival and resulted in osteoporosis in the jawbone.

Hyperglycemia induces endoplasmic reticulum stress-dependent CHOP expression in osteoblasts

Diabetic osteoporosis is a metabolic bone disease responsible for global health problems. Hyperglycemia induces osteopenia, increases bone fragility and unbalances the coupling of osteoblasts and osteoclasts. The mechanism is, however, unknown. For the purpose of this study, we hypothesized that hyperglycemia destroys endoplasmic reticulum (ER) homeostasis, activates C/EBP-homologous protein (CHOP) and induces osteoblast apoptosis under diabetic conditions. Diabetic rats were created by injecting streptozotocin (STZ) 65 mg/kg intraperitoneally and their osteoblasts were cultured under high-glucose medium in vitro. The bone mineral density (BMD) and pathological changes of the rats’ femurs were observed. The expression of CHOP in osteoblasts was assayed using immunohistochemistry and western blot analysis. Six weeks after diabetic model establishment, a significant decrease was found in the BMD of the diabetic rat femurs, and the numbers of osteoblasts under cortical bone were also reduced. The expression of the ER stress regulator CHOP in osteoblasts of diabetic rats or high-glucose medium was also elevated (P<0.01). The present results demonstrated that hyperglycemia elevated the expression of CHOP and finally led to osteoporosis. This suggested that elevating the expression of CHOP may play a role in diabetic osteoporosis.

Bone-vasculature interactions in the mandible: is bone an angiogenic tissue?

Starting from early stages of craniofacial development, the leading role of vasculature, in particular endothelial progenitor cells, becomes apparent. They are probably the cells that synthesize the appropriate bone morphogenetic protein (BMP), that precedes neural crest cell migration and determines their final destination and skeletal development. During postnatal osteosynthesis in the mandible, angiogenesis similarly goes before osteosynthesis, regulates this process with the production of BMP-2 and serves as a scaffold for osteoblasts. This growth factor is involved in bone metabolism and bone injury repair. The dependence of bone from vasculature, is better understood when looking to osseous changes that result from vasculopathies and arteritides, like in diabetes mellitus and polyarteritis nodosa respectively, that affect the mandible more frequently than previously suspected. These changes are not only the result of a dysregulation of osteoblasts and osteoclasts, but of a complex network of factors that affect the vasculature, like VEGF and hypoxia. Abnormal vasculature results in qualitatively degradated bone, with an atypical architecture or even in bone necrosis. The dynamic interplay between vasculature and bone of the mandible, with the vasculature endothelium playing an initiating and regulatory role in osteosynthesis, supports the hypothesis of an angiogenic origin of bone. This hypothesis, helps in understanding of bone pathology, like avascular necrosis and of the impact of interventions and medications that affect vasculature, on bone metabolism.

Are antiresorptive drugs effective against fractures in patients with diabetes?

We studied whether the reduction in bone turnover by use of antiresorptive drugs is detrimental in patients with diabetes who already have low bone turnover due to hyperglycemia in a nationwide cohort study from Denmark. All users of antiresorptive drugs against osteoporosis between 1996 and 2006 (n = 103,562) were the exposed group, with three age- and gender-matched controls from the general population (n = 310,683). Patients on bisphosphonates and raloxifene had a higher risk of hip, spine, and forearm fractures. However, no difference was observed in the antifracture efficacy between patients with diabetes and nondiabetic controls or between patients with type 1 and type 2 diabetes. Too few were users of strontium to allow analysis for this compound. The excess risk of fractures among patients treated with bisphosphonates or raloxifene compared to nonexposed controls was due to the higher a priori risk of fractures among patients treated for osteoporosis. Diabetes does not seem to affect the fracture-preventive potential of bisphosphonates or raloxifene. The low-turnover state of diabetes thus does not seem to be a hindrance to the effect of these drugs against osteoporosis. Therefore, patients with diabetes should receive treatment for osteoporosis in the same way as nondiabetic patients.