Rat Mandible Research Articles

The combination of odontogenic stem cells and mandibular advancement promotes the length of the mandible in adult rats by facilitating the development of condylar cartilage

BackgroundMandibular retraction is a prevalent dental and maxillofacial deformity that negatively affects patients' functional health and facial aesthetics. It has been challenging to achieve optimal outcomes for patients who have passed the peak of growth and development using only functional orthopedic treatment. There is a pressing need to explore innovative methods to promote the adaptive remodeling of adult condylar cartilage and the mandible in response to external stimuli. This study aimed to investigate the impact of varying injection frequencies of stem cells from the apical papilla (SCAPs) on the growth and development of condylar cartilage and the mandible, as well as their potential for adaptive remodeling.MethodsThe study was conducted on 8-week-old adult male Sprague–Dawley rats. The effects of SCAPs injection and different durations of mandibular advancement (MA) on the adaptive remodeling of condylar cartilage and the mandible were assessed. After the initial experimental findings, various injection frequencies of SCAPs were applied to determine the most effective conditions for promoting the growth and adaptive remodeling of condylar cartilage and the mandible during an 8-week period of mandibular advancement.ResultsThe study found that rats with extended mandibular lead times (8 weeks) or an appropriately increased frequency of mandibular leading time (once every 2 weeks or once every 1 week) exhibited increased lengths of the mandibular body and ascending branch, and a thickened full layer of condylar cartilage. The highest proportions of the proliferative layer, mature layer, and hypertrophic layer were observed in these rats. Additionally, there was a significant increase in the expression levels of SOX9 and COL2A1.ConclusionThe data from this study suggest that adult rats, even after missing their peak growth period, retain the potential for continued growth and development of their condylar cartilage. By prolonging the duration of mandibular advancement and administering injections of stem cells from the apical papilla (SCAPs), it is possible to stimulate the growth and development of the mandibular condyle.

Does Ovariectomy Affect the Mechanics of the Mandibular Alveolar Bone Structure of Wistar Rats Subjected to Tooth Loss and Modified Diet?-A FEA Study.

The aim of this study was to evaluate the mechanical effect of ovariectomy, diet, and tooth extraction on the bone structure of the mandible of Wistar rats. Mandibles from 40 female Wistar rats were used, divided into rats with ovariectomy surgery or surgical simulation. Half of the rats had the right upper incisor extracted and a soft diet was introduced for half of the animals for 30 days. After euthanasia, microtomography of the mandibles was performed for bone segmentation to construct three-dimensional models. Each mandible was subjected to a three-point bending test. The simulation by finite element method was configured according to the protocol for positioning the part on the support and force action by the load cell defined in the mechanical tests. Stress dissipation was described qualitatively on a color scale distributed in ranges of stress values. All models showed a higher concentration of stresses in the regions of force action and in the support regions, with differences in stress values and locations. Diet and dental condition interfered in the distribution of stresses, with the lateral surface of the mandible being more influenced by diet and the medial surface of the mandible by diet and dental condition.

How malocclusion interferes with tissue inhibitor of metalloproteinase-1 expression and morphology of the articular cartilage of the mandible in female rats

ObjectiveThe purpose of this study was to investigate morphological alterations and tissue inhibitor of metalloproteinase-1 expression in the articular cartilage of the mandible under conditions of experimentally induced malocclusion. DesignTwenty-four 8-week-old female Wistar rats were used and divided into control and experimental groups with two different treatment periods (2 and 4 weeks). Sagittal malocclusions were orthodontically created, causing mesial movement of the first molars and distalization of the third molars unilaterally and on opposite sides of the arches. Sagittal sections of the articular cartilage of the mandible were subjected to hematoxylin and eosin and immunohistochemistry for tissue inhibitor of metalloproteinase-1. Chi-square and MannWhitney U tests were applied. ResultsAnimals treated for 2 and 4 weeks showed morphological alterations in articular cartilage of the mandible. The main findings were thickening of the posterior third, layer derangement, osteoclast activity and osteophyte formation. Among the cellular aspects, the presence of chondrocytes with condensed nuclei and cytoplasm reduction were observed. The enzyme in control animals was observed only in the mature layer. Treated animals showed immunopositive cells in the proliferative and mature layers, and in the 2-week treated group, the posterior third of the cartilage had more immunolabeled cells than control (P=0.0291). ConclusionsThe occlusal disorder caused morphological changes in articular cartilage of the mandible, probably due to the attempt to adapt to the new condition. Tissue inhibitor of metalloproteinase-1 expression may play a role as an initial modulator in the biological events observed in articular cartilage of the mandible.

An Organic Mineral Adhesive Bone Graft: A Preclinical Study.

The development of a successful bone grafting technology with cohesive and adhesive properties has been an elusive goal for dental and orthopedic researchers. Tetracalcium phosphate combined with phosphoserine (TTCP-PS) is a synthetic, injectable, cohesive, self-setting, mineral-organic wet-field adhesive. The objective of this study was to evaluate four formulations of TTCP-PS in comparison to the conventional grafting materials, Bioglass and deproteinized cancellous bovine bone with a bioresorbable collagen membrane in standardized defects created in the angle of the rat mandible. Microcomputed tomography and histomorphometry were utilized to evaluate bone replacement with each of these materials after in vivo residence of either 4 or 12 weeks. The results of this study demonstrate that specific TTCP-PS formulations can form bone comparable to conventional materials in an osteopromotive mechanism but with the advantage of having cohesive and adhesive properties.

Examining the Impact of Acute Binge Alcohol Consumption on Trabecular Morphometry and Tensile Strength in Adolescent Sprague Dawley Rat Mandibles

Examining the Impact of Acute Binge Alcohol Consumption on Trabecular Morphometry and Tensile Strength in Adolescent Sprague Dawley Rat Mandibles

Assessment Of Nigella Sativa Oil in Dexamethasone induced Osteoporosis in Mandible of Wister Albino Rats: Experimental Study

Assessment Of Nigella Sativa Oil in Dexamethasone induced Osteoporosis in Mandible of Wister Albino Rats: Experimental Study

The potential calcium content of anchovy (Stolephorus sp.) on mandibular bone growth through osteoprotegerin expression analysis

Abstract Background: Anchovy (Stolephorus sp.) is a commonly used food ingredient due to its high calcium content, which supports craniofacial growth. Calcium stimulates the formation of osteoblasts, which produce osteoprotegerin (OPG). OPG binds to RANKL, blocking RANKL–RANK bonding and limiting osteoclast development. Objective: The objective of this study was to analyze OPG expression in mandibular bones to assess the potential calcium content of anchovies. Methods: Three groups of 27 male Wistar rats were created: control, anchovy, and milk. After 40 days, the rats were decapitated, and their mandibular bones were surgically extracted, decalcified, and prepared for microscopic examination. The results showed a significant difference in OPG expression of rat mandibles between control, anchovy, and milk groups (P < 0.05), as determined by one-way analysis of variance (ANOVA). Tukey’s HSD test revealed a significant difference in the average quantity of rat mandibular OPG expression between the control group and each of the anchovy and milk groups, with probability values of 0.00 and 0.003 (P < 0.05), respectively. However, the average level of OPG expression in anchovy and milk groups did not differ significantly, as indicated by the probability value of 0.064 (P > 0.05). Conclusion: The mandibular development increases after feeding anchovies compared to the control group. Anchovy is not statistically superior to milk in terms of increasing mandibular development. However, as a high-calcium food, anchovy is well-suited to support children’s craniofacial development and growth.

Вплив кверцетину на органічний матрикс і біомеханічні властивості нижньої щелепи щурів після її неповного перелому за умов хронічної алкогольної інтоксикації

This article investigates the impact of water-soluble form of quercetin (corvitin) on the depolymerization of the organic matrix biopolymers and biomechanical properties of the rat mandible following its incomplete fracture during chronic alcohol intoxication. The study was conducted on the 14th day after inducing chronic alcohol intoxication by daily intragastric administration of a 40% ethanol solution in a daily dose of 12 ml/kg body weight; on that day the incomplete fracture of the mandible was modelled by drilling the bone to a depth of 1 mm using a carbide drill with a diameter of 1.5 mm at a speed of up to 1000 rpm. The administration of a water-soluble form of quercetin for 14 days during the posttraumatic period in a daily dose of 10 mg/kg (in recalculation for quercetin), following an incomplete mandibular fracture during chronic alcohol intoxication, significantly reduced the activity of acid phosphatase and its tartrate-resistant isoform by 35.3% and 23.1%, respectively, as well as led to a decrease in the concentration of free hydroxyproline, hexuronic and N-acetylneuraminic acids by 17.0%, 30.6%, and 43.3%, respectively, compared to the findings revealed in animals, which did not receive the drug. The Young’s modulus exceeded the values of this group by 72.3%, the elastic limit by 53.2% the tensile strength by 59.6%, and the relative elongation to failure by 30.0%. We concluded that the administration of a water-soluble form of quercetin for 14 days following an incomplete mandibular fracture during chronic alcohol intoxication improves reparative processes in the injured area; it also restricts bone resorption and the depolymerization of connective (bone) tissue biopolymers such as collagen, proteoglycans, and sialoglycoproteins. Under these conditions, the biomechanical properties of the mandibular bone in the fracture area, particularly its elasticity and strength, are significantly enhanced.

Use of Plant Extracts in Polymeric Scaffolds in the Regeneration of Mandibular Injuries.

Severe loss of bone mass may require grafting, and, among the alternatives available, there are natural biomaterials that can act as scaffolds for the cell growth necessary for tissue regeneration. Collagen and elastin polymers are a good alternative due to their biomimetic properties of bone tissue, and their characteristics can be improved with the addition of polysaccharides such as chitosan and bioactive compounds such as jatoba resin and pomegranate extract due to their antigenic actions. The aim of this experimental protocol was to evaluate bone neoformation in experimentally made defects in the mandible of rats using polymeric scaffolds with plant extracts added. Thirty rats were divided into group 1, with a mandibular defect filled with a clot from the lesion and no graft implant (G1-C, n = 10); group 2, filled with collagen/chitosan/jatoba resin scaffolds (G2-CCJ, n = 10); and group 3, with collagen/nanohydroxyapatite/elastin/pomegranate extract scaffolds (G3-CHER, n = 10). Six weeks after surgery, the animals were euthanized and samples from the surgical areas were submitted to macroscopic, radiological, histological, and morphometric analysis of the mandibular lesion repair process. The results showed no inflammatory infiltrates in the surgical area, indicating good acceptance of the scaffolds in the microenvironment of the host area. In the control group (G1), there was a predominance of reactive connective tissue, while in the grafted groups (G2 and G3), there was bone formation from the margins of the lesion, but it was still insufficient for total bone repair of the defect within the experimental period standardized in this study. The histomorphometric analysis showed that the mean percentage of bone volume formed in the surgical area of groups G1, G2, and G3 was 17.17 ± 2.68, 27.45 ± 1.65, and 34.07 ± 0.64 (mean ± standard deviation), respectively. It can be concluded that these scaffolds with plant extracts added can be a viable alternative for bone repair, as they are easily manipulated, have a low production cost, and stimulate the formation of new bone by osteoconduction.

MINERAL COMPOSITION OF MANDIBULAR BONE TISSUE IN SIMULATED PERIODONTITIS DURING METABOLIC ACIDOSIS

Destructive changes in the mandibular cancellous bone tissue determine the severity of periodontal diseases and affect their treatment outcomes. The imbalance between macro- and microelements leads to structural and functional changes in the spongy bone tissue of the lower jaw, and when being combined with the inflammatory process in the soft tissues of the periodontium leads to the tooth loss. Mineral elements deposited in the bones are included in the body buffer systems and are able to influence the metabolic processes of the macroorganism by mobilizing them into the bloodstream.
 The aim of the study is to carry out a comparative analysis of mineral element concentrations in the bone tissue of the alveolar process of the lower jaw in rats with experimentally induced periodontitis under conditions of simulated metabolic disorders and following pharmacotherapeutic correction.
 Materials and methods. The reseach was conducted on 80 white outbred sexually mature male rats aged 2-4 months and weighing 120-200 g. The animals were divided into 5 groups (16 in each): two control groups representing NC (negative control) and PC (conditionally positive control) and three experimental groups: I Group, II Group, III Group. The NC group consisted of animals kept on a standard vivarium diet throughout the experiment. The animals of PC, I – III Groups were exposed to peridontitis simulation: the rats received 0.04% solution of ammonium chloride (NH4Cl) per os within 30 days. Animals in group III (experimental periodontitis) received intramuscular injections of 5% meldonium dihydrate solution in a dose of 0.2 mg/kg of body weight. The rats in group IV (periodontitis treatment) received "Calcium glycerophosphate" (a first-generation calcium supplement) in a dose of 133 mg/kg. Group V (combination treatment) received both the meldonium dihydrate solution and calcium glycerophosphate in the same respective doses. Tissue levels of zinc, magnesium, strontium, calcium, sodium, potassium, phosphorus, and iron were measured using atomic absorption (zinc, magnesium), atomic emission (strontium, calcium, sodium, potassium), and photometric (phosphorus, iron) methods.
 Results. The change in the amount of elements in the mandibular cancellous bone tissue reveals irregularity and different mechanisms over the course of the mineralization process, depending on the chosen means of correction. The findings obtained suggest that the corrective treatments (meldonium dihydrate, calcium glycerophosphate, or their combination) promoted gradual bone density improvement through the accumulation of studied elements in the rat mandible. This indicates potential reversibility of pathological changes at this experimental stage.
 Conclusions. The cancellous part of the mandible in rats appears to be a dynamic system, responding actively to both detrimental factors and corrective interventions by altering the content and proportions of macro- and microelements.

DYNAMICS OF BIOCHEMICAL MARKERS OF HUMORAL IMMUNITY AND METABOLISM IN MANDIBULAR BONE TISSUE UNDER INFLUENCE ON REPARATIVE OSTEOGENESIS

The scientific and practical significance of our study lies in the application of various therapeutic measures aimed at accelerating the processes of reparative osteogenesis in the presence of perforated defects in the bone tissue of the mandible using hydroxyapatite-containing osteotropic material “Biomin GT bone graft» and thymaline (injections into the surrounding soft tissues) analyzed in our article.
 The aim of the study is to investigate the dynamics of secretory immunoglobulin A content and activity of acid and alkaline phosphatases in the oral fluid of rats under the conditions of influence on the processes of reparative osteogenesis when filling the bone defect with osteotropic material and injecting thymaline into the surrounding soft tissues at different study periods.
 Materials and methods. Experimental studies were conducted on 30 mature WAG population rats weighing 160-180 g, which were divided into five groups. The control group consisted of 6 intact rats, the first group included rats with a simulated hole defect of the mandible, the second group included rats with a simulated hole defect followed by closure of the bone defect with hydroxyapatite-containing osteotropic material, the third group included rats with a mandibular defect after thymaline injections into the surrounding soft tissues, and the fourth group included animals with a defect after filling the bone defect with osteotropic material and injections of thymaline into the surrounding soft tissues. The concentration of sIgA in the oral fluid of rats was determined by enzyme-linked immunosorbent assay using «The IgA Saliva ELISA kit» (Diametra, Italy). The activity of alkaline (ALP) and acid phosphatase (AP) in the biomaterial was measured using a set of reagents “Granum» Ukraine, Kharkiv. The optical density was measured using a STAT-FAX 303+ immunoenzyme analyzer.
 Results and discussion. A decrease in the content of sIgA in the oral fluid of rats of groups I-IV was found both on day 3 and day 7 of the study compared with the control group. On the 14th day, an increase (by 16.7%) in the content of sIgA in the oral fluid of rats of group IV was determined compared to the first group. The content of sIgA in the oral fluid of rats of groups I and III remained below the control by 29.6%, 32.7%, 29.9%, respectively. On the 28th day, only in rats of group IV, sIgA exceeded the value of its content in rats of the control group and was 52.6% higher compared to rats of group I. On the 3rd day, an increase in the activity of ALP from 102% to 111%, respectively, was observed in the oral fluid of rats of groups I-IV compared to intact animals. On the 7th day, the greatest (18.9%) decrease in the activity of ALP was observed in the oral fluid of rats of group IV; on the 14th day, only rats of group IV showed a decrease in the activity of ALP (by 38.1%) compared to the 3rd day. On the 28th day, a decrease in the activity of ALP (by 43.12%) was observed in the oral fluid of rats of group IV compared to day 3 and was equal to the control. On the third day, there was an increase in the activity of AP in the oral fluid of all rats. When comparing the values of AP activity in the oral fluid of rats of groups I and IV, a difference of 17.3% was determined. In rats of group IV on day 14: 25.6% decrease in AP activity compared to day 3 of the study, although it differed from the control group. However, statistically significant decrease in AP activity was observed in rats of group IV compared to groups I-III.
 Conclusions. In rats with a simulated mandibular perforation defect on the third and seventh days of observation, a deficiency of sIgA in the oral fluid was observed, indicating a decrease in the functioning of the humoral link of local immunity. In rats of group IV, on the 14th and 28th day of the study, the sIgA content was normalized. There is an activation of reparative osteogenesis in the bone tissue of the mandible in rats with a simulated hole defect under the conditions of its subsequent closure with hydroxyapatite-containing osteotropic material and injections of thymaline into the surrounding soft tissues. The determination of biochemical markers of bone metabolism, in particular alkaline and acid phosphatase in the oral fluid in mandibular fractures, can be used in clinical practice to improve the efficiency of diagnosing reparative osteogenesis in the jaw bones.

Effect of simvastatin on the extraction socket healing in the mandible of prednisolone-treated albino rat

Effect of simvastatin on the extraction socket healing in the mandible of prednisolone-treated albino rat

A coaxial electrospun mat coupled with piezoelectric stimulation and atorvastatin for rapid vascularized bone regeneration.

The repair of critical bone defects caused by various clinical conditions needs to be addressed urgently, and the regeneration of large bone defects depends on early vascularization. Therefore, enhanced vascularization of artificial bone grafts may be a promising strategy for the regeneration of critical-sized bone defects. Taking into account the importance of rapid angiogenesis during bone repair and the potential of piezoelectric stimulation in promoting bone regeneration, novel coaxial electrospun mats coupled with piezoelectric materials and angiogenic drugs were fabricated in this study using coaxial electrospinning technology, with a shell layer loaded with atorvastatin (AVT) and a core layer loaded with zinc oxide (ZnO). AVT was used as an angiogenesis inducer, and piezoelectric stimulation generated by the zinc oxide was used as an osteogenesis enhancer. The multifunctional mats were characterized in terms of morphology, core-shell structure, piezoelectric properties, drug release, and mechanical properties, and their osteogenic and angiogenic capabilities were validated in vivo and ex vivo. The results revealed that the coaxial electrospun mats exhibit a porous surface morphology and nanofibers with a core-shell structure, and the piezoelectricity of the mats improved with increasing ZnO content. Excellent biocompatibility, hydrophilicity and cell adhesion were observed in the multifunctional mats. Early and rapid release of AVT in the fibrous shell layer of the mat promoted angiogenesis in human umbilical vascular endothelial cells (HUVECs), whereas ZnO in the fibrous core layer harvested bioenergy and converted it into electrical energy to enhance osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs), and both modalities synergistically promoted osteogenesis and angiogenesis. Furthermore, optimal bone regeneration was achieved in a model of critical bone defects in the rat mandible. This osteogenesis-promoting effect was induced by electrical stimulation via activation of the calcium signaling pathway. This multifunctional mat coupling piezoelectric stimulation and atorvastatin promotes angiogenesis and bone regeneration, and shows great potential in the treatment of large bone defects.

Biomechanical and histomorphological analysis of the mandible in rats with chronic kidney disease

The present study aimed to investigate the biomechanical and histomorphological features of mandibles in an adenine-induced chronic kidney disease–mineral and bone disorder (CKD-MBD) rat model of CKD. A total of 14 Sprague-Dawley rats were randomized into the following two groups: control group and CKD group. At the end of the sixth week, all rats were euthanized, and serum was collected for biochemical marker tests. Macroscopic bone growth and biomechanical parameters were measured in the right hemimandible, while the left hemimandible was used for bone histomorphometric analysis. Compared to the control group, the CKD group showed a significant increase in serum creatinine, blood urea nitrogen, and serum parathyroid hormone at the end of the sixth week. The biomechanical structural properties significantly decreased in the CKD group compared to the control group. Bone histomorphometric analysis indicated that the trabecular bone volume of rats in the CKD group was significantly lower than that of the control group. In the CKD groups, the bone formation parameters of the trabecular bone were significantly increased, while the bone mineralization apposition rates of both the trabecular bone and periosteal cortical bone were significantly increased. The rat CKD model showed deteriorated structural mechanics, low trabecular bone volume, high trabecular bone formation, increased trabecular bone mineralization apposition rate, and increased cortical bone mineralization apposition rate, which met the characteristics of osteitis fibrosa, indicating that this model is a useful tool for the study of mandible diseases in CKD patients.

Quercetin suppresses ovariectomy-induced osteoporosis in rat mandibles by regulating autophagy and the NLRP3 pathway.

With the aging population and the popularity of implant prostheses, an increasing number of postmenopausal osteoporosis (PMOP) patients require implant restorations; however, poor bone condition affects the long-term stability of implant prostheses. This study aimed to investigate the therapeutic effect of quercetin (QR) compared with alendronate (ALN), the primary treatment for PMOP, on mandibular osteoporosis (OP) induced by ovariectomy (OVX) in female rats. Adult female rats were treated with QR (50 mg/kg/day), ALN (6.25 mg/kg/week) by gavage for 8 weeks, chloroquine (CQ, 10 mg/kg/twice a week), and cytokine release inhibitory drug 3 (MCC950, 10 mg/kg/three times a week) by intraperitoneal injection for 8 weeks after bilateral OVX. Blood samples were collected prior to euthanasia; the mandibles were harvested and subjected to micro-computed tomography (micro-CT) and pathological analysis. QR administration controlled weight gain and significantly improved the bone microstructure in OVX rats, increasing bone mass, and bone mineral density (BMD), reducing bone trabecular spacing, and decreasing osteoclast numbers. Western blotting, real-time quantitative PCR (RT-qPCR), and serum markers confirmed that QR inhibited interleukin- 1β (IL-1β) and interleukin-18 (IL-18) on the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) protein 3 (NLRP3) pathway thereby inhibiting osteoclast differentiation, immunofluorescence and western blotting also confirmed that QR inhibited autophagy in OVX rats and suppressed the number of tartrate-resistant acid phosphatase (TRAP)-stained positive osteoclasts. The findings suggest that QR may protect the bone structure and prevent bone loss in osteoporotic rats by inhibiting the NLRP3 pathway and autophagy in osteoclasts with comparable effects to ALN, thus QR may have the potential to be a promising alternative supplement for the preventive and therapeutic treatment of PMOP.

Hypoxia dissociates HDAC6/FOXO1 complex and aggregates them into nucleus to regulate autophagy and osteogenic differentiation.

This research aimed to elucidate the molecular mechanisms underlying the periodontitis-associated bone loss, with particular emphasis on the contributory role of hypoxic microenvironment in this process. Periodontitis generally causes alveolar bone loss and is often associated with a hypoxic microenvironment, which affects bone homeostasis. However, the regulating mechanism between hypoxia and jaw metabolism remains unclear. Hypoxia triggers autophagy, which is closely related to osteogenic differentiation, but how hypoxia-induced autophagy regulates bone metabolism is unknown. HDAC6 and FOXO1 are closely related to bone metabolism and autophagy, respectively, but whether they are related to hypoxia-induced bone loss and their internal mechanisms is still unclear. Established rat nasal obstruction model and hypoxia cell model. Immunohistochemistry was performed to detect the expression and localization of HDAC6 and FOXO1 proteins, analysis of autophagic flux and transmission electron microscopy was used to examine the autophagy level and observe the autophagosomes, co-immunoprecipitation and chromatin immunoprecipitation were preformed to investigate the interaction of HDAC6 and FOXO1. Hypoxia causes increased autophagy and reduced osteogenic differentiation in rat mandibles and BMSCs, and blocking autophagy can attenuate hypoxia-induced osteogenic differentiation decrease. Moreover, hypoxia dissociated the FOXO1-HDAC6 complex and accumulated them in the nucleus. Knocking down of FOXO1 or HDAC6 alleviated hypoxia-induced autophagy elevation or osteogenic differentiation reduction by binding to related genes, respectively. Hypoxia causes mandibular bone loss and autophagy elevation. Mechanically, hypoxia dissociates the FOXO1-HDAC6 complex and aggregates them in the nucleus, whereas HDAC6 decreases osteogenic differentiation and FOXO1 enhances autophagy to inhibit osteogenic differentiation.

Analysis of the Induced Membrane Technique in the Rat Mandible

Analysis of the Induced Membrane Technique in the Rat Mandible

Osteogenic effect and mechanism of IL-10 in diabetic rat jaw defect mode.

The aim of this study was to investigate the effect of IL-10 on the phenotype polarization of macrophages and osteogenesis in diabetes mellitus type 2 (T2DM) rat jaw defects. Lipopolysaccharide (LPS) and interleukin-10 (IL-10) were chosen to induce the polarization of macrophages. In vitro assessment included wound-healing assay, western blotting, and alizarin red staining after co-culture of the bone marrow-derived mesenchymal stem cells (BMSCs) and induced macrophages. For in vivo study, IL-10 was loaded on GelMA-Heparin and applied to bone defects of the alveolar ridge in diabetic rats, while Bio-Oss Collagen, simple GelMA-Heparin, and blank control groups were set for contrast experiment. The mandibles of rats were processed for micro-computed tomography, histology, and immunohistochemistry 1 week and 4 weeks after the operation. IL-10 induced expression of arginase 1, TGF-β1, EGR2, and Mannose Receptor (CD206), whereas LPS induced expression of iNOS, TNF-α, IL-6, CD80. The BMSCs co-cultured with macrophages induced by IL-10 showed increased migration, osteogenic differentiation, and mineralization in vitro. Notably, the IL-10-laden GelMA-Heparin group showed quicker new bone formation and a higher M2/M1 ratio of macrophages in the jawbone defect area compared with the control groups. IL-10 can stably induce macrophages to M2 type, thereby influencing BMSCs and improving the osteogenesis of jaw bone defects.

Hypoxia caused by unilateral nasal obstruction decreases mandibular density in rats through inhibition of Cyp1a1 expression.

Oral breathing has an important impact on morphology and bone mineral density (BMD) in a mandible. This study aimed to investigate the hub genes and mechanism regulating the mandibular BMD decrease induced by nasal obstruction. A unilateral nasal obstruction model was established in 1-week-old Wistar rats by electrocautery obstruction. BMD of the mandible was determined by micro-computed tomography. Transcriptome analysis was performed to identify differentially expressed genes (DEGs). Hub genes were identified by building protein-protein interaction network and verified by western blot. A hypoxic cell model was established in bone marrow mesenchymal stem cells (BMSCs) by using CoCl2. The expression of hypoxia-inducible factor-1α (HIF-1α), NF-kB ligand-receptor activator (RANKL), osteoprotegerin (OPG), and Cyp1a1 was detected by western blot. The mandibular BMD of rats in the unilateral nasal obstruction group was significantly decreased. A total of 38 DEGs were identified in nasal obstruction rats compared with normal rats. A ratio of RANKL/OPG in the mandible was elevated by nasal obstruction, while the Cyp1a1 was decreased. In vitro, the HIF-1α expression and RANKL/OPG ratio were upregulated by hypoxia while the Cyp1a1 expression was decreased. Pretreatment with Cyp1a1 activator, FICZ, could increase the expression of Cyp1a1 while attenuating the activation of HIF-1α and RANKL. Respiratory changes caused by nasal obstruction contribute to the decrease in Cyp1a1 expression in the mandible of juvenile rats, which is associated with disturbances in bone homeostasis controlled by the RANKL/OPG ratio.

Effect of long-term intake of liquid nutrition on the development and maintenance of the weight and size of the skull, mandible, and teeth in rats.

The consistency of the diet may affect the development and maintenance of the muscular and bony parts of the masticatory apparatus. Therefore, we investigated the effect of chronic intake of liquid nutrition (Fresubin) on the growth and maintenance of the weight and size of the skull, mandible, and teeth in Wistar rats fed with liquid nutrition during different developmental periods: (i) from weaning to adulthood, (ii) only in the juvenile period, or (iii) only in adulthood. We found that in all groups of rats fed with liquid nutrition, the skull and the mandible were significantly lighter in weight than those of control rats fed exclusively with pelleted chow from weaning to adulthood. In addition, in rats fed with liquid nutrition, the length of the mandible was significantly increased, whereas the height of the mandible and the length of the upper incisors were reduced. Our data indicate that food consistency may profoundly affect the growth pattern and the maintenance of the mass and size of skull bones and teeth during different periods of life. The extent of the effect was found to depend on the period during which liquid nutrition is provided and on the duration of its intake. In conclusion, the findings indicate that prolonged intake of liquid nutrition can significantly affect the development of the bone part of the masticatory apparatus.