Calcium phosphate cement with icariin-loaded gelatin microspheres as a local drug delivery system for bone regeneration.

BACKGROUND: Icariin (ICA), a main active ingredient of Herba Epimedium, could promote bone formation, inhibit bone resorption and alleviate inflammatory responses. The aim of this study was to investigate the effect of ICA on the inhibition of bacteria associated with peri-implantitis, and fabricate a calcium phosphate cement (CPC) with ICA-loaded gelatin microspheres (GMs) as a local drug delivery system efficiently promoting bone formation and alleviating inflammation. RESULTS: In this study, ICA exhibited antibacterial activity against P. gingivalis with a MIC value of 1 × 10-4 mol/L. When the concentration of ICA was 0.5 mM, the encapsulation efficiency of GMs reached the maximum value of 76.26 ± 3.97%. GMs with ICA revealed a controlled release profile, 0.5 mM ICA exhibited a higher ICA release profile than the other groups during a 21 d monitoring span. The results of SEM and XRD demonstrated successful fabrication of a calcium phosphate cement with ICA-loaded GMs. ICA released from CPC/GMs (ICA) was slower than ICA released from GMs within 10 days. CPC/GMs (ICA) exhibited antibacterial activity against P. gingivalis, but the antibacterial rate of CPC/GMs (ICA) was only 17.15 ± 6.06%. In addition, CPC/GMs (ICA) promoted the proliferation of BMSCs and significantly stimulated the differentiation and maturation of BMSCs. In vivo, H&E and Masson staining experiments demonstrated that CPC/GMs (ICA) exhibited better capacity for bone regeneration than CPC/GMs and CPC, and the expression of TNF-α and IL-1ß in the tissue around CPC/GMs (ICA) was significantly lower than CPC/GMs and CPC in IHC staining (P < 0.05). CONCLUSION: In this study, ICA exhibited limited antibacterial activity against bacteria associated with peri-implantitis. A composite material of calcium phosphate cement with ICA-loaded gelatin microspheres was developed, which not only promoting osteoinductivity and bone formation, but also alleviating inflammation, demonstrating its potential as a promising bone substitute material for treatment of peri-implantitis.

TMT-labelled quantitative proteomic analysis to predict the target promoting human odontogenic inflammatory granulation tissue transform into reparative granulation tissue.

OBJECTIVES: Odontogenic inflammatory diseases are main causes for alveolar bone breakdown and teeth loss, leaving great difficulties in denture restoration. Local inflammatory granulation tissue (IGT) is considered as pathological tissue and required to be removed. However, there are many evidences supporting that under appropriate intervention, IGT in alveolar bone maybe transformed into reparative granulation tissue (RGT), followed by ossification. Therefore, this study aimed to discover a specific target to promote this transformation. MATERIALS AND METHODS: After drawing out histological differences between IGT and RGT with haematoxylin and eosin (H&E) and immunohistochemical (IHC) assay staining, TMT-labelled quantitative proteomic analysis was applied to identify potential targets. RESULTS: The most striking histological property of RGT was found to be ECM deposition, which significantly decreased inflammatory cells, prominently increased fibroblasts as well as triggered changes of vascular types. Combined with histological findings and proteomic analysis, five KEGG pathways were associated with ECM, inflammation and angiogenesis and 49 pathways involved in differentially expressed proteins. COL1A1 was not only the most up-regulated protein, but also one of main hubs in protein-protein interaction regulatory network. Specific protease cathepsin K (CTSK) was identified. Level of CTSK in RGT was down-regulated to 69.10-76.97% (p < .05), with significantly up-regulated COL1A1, COL1A2, FN1 and TGFB1 included in focal adhesion, PI3K-Akt signalling pathways and angiogenesis. CTSK involved in transformation from IGT to RGT. CONCLUSIONS: CTSK might be a target to regulate transformation from IGT to RGT in alveolar bone through ECM, stem cells and angiogenesis mechanisms. However, further research is also clearly required.

Studies on the Performance of Molar Porous Root-Analogue Implant by Finite Element Model Simulation and Verification of a Case Report.

PURPOSE: The aim of this study was to evaluate the effect of porous layer thickness in a 3-dimensionally printed 1-piece molar porous root-analogue implant (RAI) on the biomechanical properties of the peri-implant bone and the clinical efficacy of one such implant in a patient. MATERIALS AND METHODS: Three RAIs with different superficial porous layer thicknesses (0.5 mm, 1 mm, and fully porous) were designed and assembled using a mandible model and then solidified to obtain 3 finite elements models, denoted A, B, and C. Finite element analysis was performed to analyze the stress on the solid and porous structures of the RAIs and the stress and strain experienced by the bone surrounding the implant. RAIs were fabricated by selective laser melting. An unrepairable molar in a single patient was selected for replacement. An RAI was designed and prepared and then implanted into the alveolar bone immediately after minimally invasive extraction of the damaged tooth. Definitive restorations were placed after a 3-month period of uninterrupted healing. RESULTS: The stress concentration observed in the 3 types of RAI was principally between the solid and porous interface contact points, with maximum stress on the solid and porous structures smaller than that of the respective yield strength. The introduction of a porous structure on the surface of the RAIs increased peri-implant bone stress, which increased with thickness of the porous layer. The 3-dimensionally printed porous RAI exhibited excellent initial stability immediately after implantation. After continual observation for 6 months, it was found that bone surrounding the root had infiltrated into the RAI, achieving good osseointegration. CONCLUSIONS: Stress shielding can be reduced by decreasing the elastic modulus of the implant, with the interface between implant and bone allowing more appropriate stress conduction. A 1-piece porous RAI fabricated using 3-dimensional printing establishes a new indication for immediate implantation after extraction.

Influence of the lateral pterygoid muscle on traumatic temporomandibular joint bony ankylosis.

BACKGROUND: The pathogenesis of traumatic TMJ ankylosis remains unclear. This study aimed to verify the role of the lateral pterygoid muscle in the pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis. METHODS: Eight 6-month-old male sheep were used in this study. Bilateral TMJ osteotomies were performed to induce sagittal fractures of the mandibular condyle. The lateral one-fourth segment of the disc was removed to establish a model of TMJ bony ankylosis. Subsequently, the function of the left and right lateral pterygoid muscles was blocked (experimental group) or maintained (control group), respectively. At 12 weeks postoperatively, animals were sacrificed and TMJ complex samples were evaluated by gross observation, spiral computed tomography (CT), micro-CT, and histological examinations. RESULTS: Gross observation revealed bony ankylosis in the control TMJs and fibrous adhesions in the experimental TMJs. Spiral CT and micro-CT demonstrated that, compared to the experimental group, the control group showed calcified callus formation in the joint space and roughened articular surfaces after new bone formation, which protruded into the joint space. Maximum mediolateral and anteroposterior condylar diameters were significantly larger in the control group than in the experimental group. Micro-CT also showed that the primary growth orientation of new trabeculae was consistent with the direction of lateral pterygoid traction in the control group, but not in the experimental group. Histological examination showed fibro-osseous ankylosis in the control group, but not in the experimental group. CONCLUSIONS: The lateral pterygoid simulates the effects of distraction osteogenesis, which is an important factor in the pathogenesis of TMJ bony ankylosis during the healing of sagittal condylar fractures.

Observational Study of Surgical Treatment of Sagittal Fractures of Mandibular Condyle.

OBJECTIVE: This study was conducted to investigate the complications that occur after surgical treatment of sagittal fracture of the mandibular condyle (SFMC). METHODS: A retrospective study was conducted on patients in whom SFMC was treated using surgical methods (87 patients, 105 sides) between January 1995 and December 2011 (79 sides were treated by rigid internal fixation and the remaining 26 sides were removed the condylar fragments). The longest follow-up was 17 years, and the shortest was 2 years. Follow-ups were conducted to assess mandibular activity, mouth opening, and computed tomography scans of condylar morphologic alterations. The postoperative complications were evaluated and the causes were analyzed. RESULTS: We observed 3 patients with joint ankylosis (all of them were removed the condylar fragments); 8, mouth opening less than 30 mm; 23, deviation on mouth opening at 6 months. At 4 weeks, 19 patients had facial nerve weakness, which was resolved within 6 months. The radiological investigation showed complete remodeling in 56.2% of the condyles (in the 59 sides, 57 sides were treated by rigid internal fixation and 2 sides were removed the condylar fragments); partial remodeling 27.6% condyles (in the 29 sides, 20 sides were treated by rigid internal fixation and 9 sides were removed the condylar fragments); poor remodeling, 16.2% condyles (in the 17 sides, 2 sides were treated by rigid internal fixation and 15 sides were removed the condylar fragments). CONCLUSIONS: Surgical treatment of SFMC is not perfect. There were some complications that occurred after the surgical treatment of SFMC. The findings also indicate that condylar anatomic reduction is the basis for functional recovery and, therefore, rigid fixation should be implemented. Furthermore, the removal of condylar fragments should be performed with caution, and if used, the fragments should be removed entirely.

[Study on NaOH improving the surface morphology of three-dimensional printed poly- L- lactic acid mesh scaffolds].

Objective: To explore the effect of NaOH on the surface morphology of three-dimensional (3D) printed poly- L-lactic acid (PLLA) mesh scaffolds. Methods: The 3D printed PLLA mesh scaffolds were prepared by fused deposition molding technology, then the scaffold surfaces were etched with the NaOH solution. The concentrations of NaOH solution were 0.01, 0.1, 0.5, 1.0, and 3.0 mol/L, and the treatment time was 1, 3, 6, 9, and 12 hours, respectively. There were a total of 25 concentration and time combinations. After treatment, the microstructure, energy spectrum, roughness, hydrophilicity, compressive strength, as well as cell adhesion and proliferation of the scaffolds were observed. The untreated scaffolds were used as a normal control. Results: 3D printed PLLA mesh scaffolds were successfully prepared by using fused deposition molding technology. After NaOH etching treatment, a rough or micro porous structure was constructed on the surface of the scaffold, and with the increase of NaOH concentration and treatment time, the size and density of the pores increased. The characterization of the scaffolds by energy dispersive spectroscopy showed that the crystal contains two elements, Na and O. The surface roughness of NaOH treated scaffolds significantly increased ( P<0.05) and the contact angle significantly decreased ( P<0.05) compared to untreated scaffolds. There was no significant difference in compressive strength between the untreated scaffolds and treated scaffolds under conditions of 0.1 mol/L/12 h and 1.0 mol/L/3 h ( P>0.05), while the compression strength of the other treated scaffolds were significantly lower than that of the untreated scaffolds ( P<0.05). After co-culturing the cells with the scaffold, NaOH treatment resulted in an increase in the number of cells on the surface of the scaffold and the spreading area of individual cells, and more synapses extending from adherent cells. Conclusion: NaOH treatment is beneficial for increasing the surface hydrophilicity and cell adhesion of 3D printed PLLA mesh scaffolds.

Clustering human dental pulp fibroblasts spontaneously activate NLRP3 and AIM2 inflammasomes and induce IL-1ß secretion.

Objectives: The objective of the present study was to investigate whether NOD-like receptor family pyrin domain-containing 3 (NLRP3) and absent in melanoma 2 (AIM2) inflammasomes pathways were involved in an experimental model of fibroblast activation named nemosis, which was used to mimic circumstances without bacteria stimulation. Methods: Nemosis of human dental pulp fibroblast (DPFs) was induced by three-dimensional culture in U-shaped 96-well plates and investigated by scanning electron microscopy (SEM). DPFs monolayers were used as control. Annexin V-FITC/7-AAD apoptosis assay was performed on the DPFs spheroids by flowcytometry. Caspase-1 activity detection assay was conducted on the DPFs spheroids. Quantitative real-time polymerase chain reaction (qRT-PCR), cytokine measurements, Western blot and the effect of COX-2 inhibitor on spheroids was studied. Results: SEM study observed human dental pulp fibroblast clusters and cell membranes damage on the surface of DPFs spheroids. The percentages of necrotic cells from DPFs spheroids gradually increased as the incubation time increased. A statistically significant increase in caspase-1 activity was observed after DPFs spheroids formation. DPFs spheroids displayed significant amounts of NLRP3, AIM2 mRNA and protein expression, caspase-1 mRNA expression and cleaved Caspase-1 protein expression and high IL-1ß concentrations (P < 0.05) than DPFs monolayers. Specific COX-2 inhibitor (NS-398) decreased NLRP3 mRNA and protein expression, cleaved Caspase-1 protein expression, Caspase-1 activity and IL-1ß mRNA expression and IL-1ß concentrations (P < 0.05). However, Specific COX-2 inhibitor had no impact on AIM2 mRNA and protein expression, caspase-1 mRNA expression and pro-Caspase-1 protein expression. Conclusions: In conclusion, clustering human DPFs spontaneously activated NLRP3 and AIM2 inflammasomes and induced IL-1ß secretion which could be partially attenuated by COX-2 inhibitor. Thus, nemosis could become a powerful model for studying mechanisms underlying aseptic pulpitis.

[Comparative efficacies of non-surgical treatment for pediatric and adult sagittal fractures of mandibular condyle].

OBJECTIVE: To compare the efficacies of non-surgical treatment for pediatric and adult sagittal fractures of mandibular condyle. METHODS: From January 1985 to December 2010, our department treated 67 cases (82 sides) sagittal fractures of mandibular condyle with occlusal splint at a height of 1-2 mm in molar region for six months or other non-surgical treatment. Their clinical and radiological remodeling of affected condyles after treatment were reviewed at six mouths, one year and each year after treatment. They were divided into 2 groups according to age. There were 28 patients (34 sides) aged over 12 years and 39 patients (48 sides) under 12 years. During a follow-up period of 2-25 years, mandibular activity, mouth opening and parallel CT scan of condylar morphological alterations were examined. RESULTS: Under 12-year-old group:good mandibular function was observed in 39 patients. Maximal mouth opening over 35 mm was achieved at 6 months.Only 11 of 39 patients had deviation on mouth opening at 6 months.Radiological studies showed that 32 condyles were complete remodeling and 16 condyles were partial remodeling. Poor remodeling was not observed. Over 12-year-old group:Ankylosis occurred in 4 joints. And 15 of 28 patients had deviation on mouth opening at 6 months.Radiological studies showed the remodeling of condyles was complete (n = 6), partial (n = 16) and poor (n = 12) respectively. CONCLUSION: Mandibular functional recovery and condylar remodeling are better in children with more powerful healing and reconstructing capacities.

[Analysis of human mandible and temporomandibular joint using three-dimensional finite element method under different mechanical models].

OBJECTIVE: Analysis the result of human mandible and temporomandibular joint using two different three-dimensional finite element method under different mechanical models. METHODS: The 3-dimensional model including cortical and cancellous bone for human mandible was obtained through computed tomography (CT) scan. Then the model was meshed in the software ICEM CFD. The passive and active muscle-force loadings were separately applied on the FE model to simulate the anterior clenching. Stress distributions in two models were compared. RESULTS: The stress distributions of two models were apparently different. In the passive muscle-force model, high stress was mainly distributed in mandibular angle, retromolar trigone, notch and bite point on crown. In the active muscle-force model, high stress was mainly distributed in condylar vertex and neck, mandibular angle, retromolar trigone and bite point on crown. There were some similarities between passive and active muscle loadings. However, large difference existed in condylar region due to the vertices reaction force disparity. CONCLUSION: Closer to actual stressing state of human mandible and temporomandibular joint, the active muscle-force model is a proper biomechanical model for human mandible under anterior clenching.

Glucagon-like peptide-1 receptor promotes osteoblast differentiation of dental pulp stem cells and bone formation in a zebrafish scale regeneration model.

Bone cells express the glucagon-like peptide 1 receptor (GLP-1R). However, its presence and role in human dental pulp derived stem cells (hDPSCs) remains elusive. Hence, in the current study, we isolated hDPSCs and differentiated them into osteoblasts, where GLP-1R expression was found to be upregulated during osteoblast differentiation. GLP-1 receptor agonist, liraglutide peptide treatment, increased osteoblast differentiation in hDPSCs by increasing calcium deposition, ALP activity, and osteoblast marker genes, Runx2, type 1 col, osteonectin, and osteocalcin. Furthermore, activation of long non-coding RNA (LncRNA) LINC00968 and microRNA-3658 signalling increased Runx2 expression. Specifically, liraglutide increased LncRNA-LINC00968 expression while decreasing miR-3658 expression. LINC00968 targets miR-3658, and miR-3658 targets Runx2. Additionally, in an in-vivo study, zebrafish scale regeneration model, liraglutide promoted calcium deposition, osteoblastic cell count, collagen 1α, osteonectin, osteocalcin, runx2a MASNA isoform expression (transcribed from promoter P1), and Ca/P ratio in scales. Overall, GLP-1R activation promotes osteoblast differentiation via Runx2/LncRNA-LINC00968/miR-3658 signalling in hDPSCs and promotes bone formation in zebrafish scale regeneration.

Calcium phosphate cement with minocycline hydrochloride-loaded gelatine microspheres for peri-implantitis treatment.

OBJECTIVES: This study aimed to fabricate an antibacterial calcium phosphate cement (CPC) with minocycline hydrochloride (MINO)-loaded gelatine microspheres (GMs) as a local drug delivery system for the treatment of peri­implantitis. METHODS: CPC/GMs(MINO), incorporating MINO-loaded GMs into CPC, was developed and characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), and drug release profiling. The antibacterial activity against Porphyromonas gingivalis and Fusobacterium nucleatum was evaluated. Bone mesenchymal stem cells (BMSCs) were cultured in the extracts of the developed cements to evaluate osteoinductivity in vitro. Furthermore, a rabbit femoral model was established to evaluate osteogenic ability in vivo. RESULTS: SEM and XRD confirmed the porous structure and chemical stability of CPC/GMs(MINO). The release profile showed a sustained release of MINO from CPC/GMs(MINO), reaching an equilibrium state on the 14th day with a cumulative release ratio of approximately 84%. For antibacterial assays, the inhibition zone of CPC/GMs(MINO) was 3.67 ± 0.31 cm for P. gingivalis and 7.47 ± 0.50 cm for F. nucleatum. Most bacteria seeded on CPC/GMs(MINO) died after 24 h of culture. In addition, CPC/GMs(MINO) significantly enhanced alkaline phosphatase activity, osteogenic gene expression, and BMSC mineralisation compared with CPC/GMs and the control group (P < 0.05). The in vivo results showed that CPC/GMs(MINO) possessed a higher quality and quantity of bone formation and maturation than CPC/GMs and CPC. CONCLUSIONS: CPC/GMs(MINO) showed excellent antibacterial activity against pathogens associated with peri­implantitis and demonstrated good osteoinductivity and osteogenic ability. CLINICAL SIGNIFICANCE: Peri-implantitis is among the most common and challenging biological complications associated with dental implants. In this study, MINO-loaded GMs were incorporated into CPC, which endowed the composite cement with excellent antibacterial and osteogenic abilities, demonstrating its potential as a bone graft substitute for treating peri­implantitis.

3D printing titanium grid scaffold facilitates osteogenesis in mandibular segmental defects.

Bone fusion of defect broken ends is the basis of the functional reconstruction of critical maxillofacial segmental bone defects. However, the currently available treatments do not easily achieve this goal. Therefore, this study aimed to fabricate 3D-printing titanium grid scaffolds, which possess sufficient pores and basic biomechanical strength to facilitate osteogenesis in order to accomplish bone fusion in mandibular segmental bone defects. The clinical trial was approved and supervised by the Medical Ethics Committee of the Chinese PLA General Hospital on March 28th, 2019 (Beijing, China. approval No. S2019-065-01), and registered in the clinical trials registry platform (registration number: ChiCTR2300072209). Titanium grid scaffolds were manufactured using selective laser melting and implanted in 20 beagle dogs with mandibular segmental defects. Half of the animals were treated with autologous bone chips and bone substances incorporated into the scaffolds; no additional filling was used for the rest of the animals. After 18 months of observation, radiological scanning and histological analysis in canine models revealed that the pores of regenerated bone were filled with titanium grid scaffolds and bone broken ends were integrated. Furthermore, three patients were treated with similar titanium grid scaffold implants in mandibular segmental defects; no mechanical complications were observed, and similar bone regeneration was observed in the reconstructed patients' mandibles in the clinic. These results demonstrated that 3D-printing titanium grid scaffolds with sufficient pores and basic biomechanical strength could facilitate bone regeneration in large-segment mandibular bone defects.

[Applied anatomy of the stylomastoid foramina and its relation to the surrounding bone structures].

PURPOSE: To study the relationship between the stylomastoid foramen and surrounding bony structures, enrich anatomical data and provide reference for clinical surgery. METHODS: A total of 62 intact and dry adult skulls were selected. The shape of the stylomastoid foramen was observed, the diameter of the stylomastoid foramen, the distances from the posterolateral point and the anterior medial point to the surrounding bony structures were measured with a vernier caliper. SPSS 25.0 software package was used to analyze the data. RESULTS: There were four shapes of stylomastoid foramen, i.e., circular (61.29%), oval (29.84%), irregular (8.06%) and triangular (0.81%). The circular diameter was (2.80±0.61) mm, the oval long and short diameters were (4.43±0.96) and (2.79±0.60) mm. Distances from the posterolateral and anterior medial points of the stylomastoid foramen to the posterolateral point of the external opening of the carotid canal, the anterior medial point of the jugular foramen, the midline, the most anterior point of the foramen magnum, the posterior point of the great palatine foramen, the posterolateral point of the foramen lacerated, the foramen ovale, the posterolateral point of the foramen spinosum, the anterior point of the styloid process root, the outermost point of the tympanomastoid fissure and the tip of the mastoid process were (16.10±2.81), (24.01±2.65), (44.95±3.24), (45.10±2.71), (61.66±4.14), (35.56±4.35), (32.26±2.85), (29.12±3.40), (10.39±3.25), (9.49±2.24) and (12.01±2.79) mm; (12.80±2.41), (21.56±2.51), (42.96±3.97), (42.91±2.76), (58.97±3.97), (32.98±4.14), (29.20±2.77), (25.80±2.87), (7.37±2.33), (11.42±2.00) and (15.41±2.57) mm, respectively. Statistical analysis showed that there was no significant difference in the apertures and distances between the left and right side(P＞0.05). CONCLUSIONS: Most of the stylomastoid foramen are round and oval, understanding the distance between the foramen and surrounding bony structures is helpful for guiding clinical operations and enriching anatomical knowledge.

Evaluation of Root-Analog Implants and Standardized Specimens Fabricated by Selective Laser Melting.

PURPOSE: To evaluate root-analog implants (RAIs) fabricated by selective laser melting (SLM). MATERIALS AND METHODS: Two types of implants (a maxillary right first molar RAI and a screw-cylinder-type molar implant) were designed using CAD software. Both implant types were fabricated with the SLM technique using Ti-6Al-4V powder. The stress distribution and micromotion of the implants were evaluated using finite element analysis, and the mechanical properties of the printed implants (relative density and compression test), surface properties of an SLM-fabricated specimen (morphology, roughness, and contact angle test), and biocompatibility of an SLM-fabricated specimen (osteoblast attachment, metal ion precipitation analysis, cell viability, and osteogenic gene expression) were evaluated. RESULTS: The RAI model exhibited better stress distribution and less micromotion than the screw-cylinder implant model. The screw-cylinder implant was better than the RAI at withstanding pressure, but both implant types could withstand masticatory forces. The densities of both implant types were similar to those of the bulk materials. Block samples made using the same SLM technique as the RAI exhibited good surface properties and excellent biocompatibility. CONCLUSION: The properties of the molar RAI fabricated with the SLM technique suggest that it may have potential for future clinical use, but this will need to be verified by in vivo studies.

Evaluation of the mechanical properties and fit of 3D-printed polyetheretherketone removable partial dentures.

Compared with CAD/CAM, fused deposition modeling (FDM) 3D printing technology is simple and safe to operate and has a low cost and high material utilization rate; thus, it is widely used. The present investigation aimed to evaluate the mechanical properties and fit of polyetheretherketone (PEEK) removable partial dentures (RPDs) constructed by FDM. We analyzed mechanical properties of PEEK samples prepared by FDM, milling, or injection molding. RPDs were designed and finite element analysis models was constructed to evaluate maximum stress and strain in the RPDs, cortical bone and mucosa. Geomagic Qualify software was used to analyze gaps between the model and the tissue surface of the framework. The results showed that the compressive strength of the 3D-printed PRDs was greater than that of the injection-molded samples. Finite element analysis demonstrated that the maximum stress on the PRDs was less than the yield strength of the material. Overall, the mechanical properties and fit of the PEEK RPD fabricated by FDM technology essentially fulfilled clinical requirements.

Development of the temporomandibular joint in miniature pig embryos.

The temporomandibular joint (TMJ) is a synovial joint involved in sliding and hinge movements of lower jaw in mammals. Studies on TMJ development in embryos have been mainly performed using rodents. However, the TMJ structure in rodents differs in several aspects from that in humans. There are few studies on the embryonic development of TMJ in large mammals. In the present study, we investigated the embryonic developmental characteristics of the TMJ in pigs histologically. Embryonic day 35 (E35), E45, E55, E75, E90, and postnatal day 1(P1) embryos/fetuses from the pigs were used for the study. The results showed condensation of mesenchymal cells on E35. The inferior articular cavity was formed on E45, together with a narrow crack in the superior articular cavity region. The superior and inferior articular cavities and articular disc of the TMJ were completely formed on E55. On E75, the condyle showed an obvious conical shape and the superior and inferior joint cavities were enlarged. Furthermore, the mandibular ramus and mandibular body under the neck of the condyle were ossified from E75 to P1 day. The chondrocyte layer of the condyle was significantly thinner from E75 to P1. It is speculated that the spatiotemporal development of the TMJ in miniature pig embryos is similar to that in humans. Embryonic development of the pig TMJ is an important bridge for translating the results of rodent research to medical applications.

Immediate, non-submerged, three-dimensionally printed, one-piece mandibular molar porous root-analogue titanium implants: A 2-year prospective study involving 18 patients.

This study prospectively evaluated non-submerged, three-dimensionally printed, one-piece molar porous root-analogue titanium implants. A total of 18 non-restorable multiple-rooted teeth in 18 patients, aged 22-64 years, were included in this study. A series of computed tomography images of the mandible were selected and rendered into a digital model. The non-restorable mandibular molars were digitally separated from the surrounding alveolar bone, and served as the template on which the porous root-analogue titanium implants (RAIs) were designed with computer-aided design (CAD) software. The porous molar RAIs were fabricated with the selective laser melting technique (average particle size 20 µm) and inserted into the alveolar sockets after extraction of the non-restorable molars. Definitive restorations were placed after 3 months of uninterrupted healing. Peri-implant clinical and radiographic measurements were obtained 2 years later. All patients functioned well following 2 years of functional loading, and peri-implant clinical and radiographic measurements demonstrated implant stability. No implants were lost at the 2-year follow-up, and the survival rate was 100%. Three-dimensionally printed one-piece molar porous RAIs may be a promising option for the replacement of non-restorable molars that are planned for extraction. Additional studies are required to evaluate the long-term survival of implants fabricated using this technique.

An evaluation of allogeneic freeze-dried concentrated growth factors biocompatibilityin vitroandin vivo.

This study evaluated the biocompatibility of allogeneic freeze-dried concentrated growth factors (AFD-CGFs)in vitroandin vivo.For thein vitroexperiments, bone marrow stem cells (BMSCs) were cultured in 10% fresh allogeneic concentrated growth factors (CGFs). AFD-CGF solution was used as the experimental group, and Dulbecco's modified Eagle medium was used as control. Transmission electron microscopy (TEM) showed that the cell ultrastructure was unchanged, and membranes were intact. Scanning electron microscopy, cell counting kit-8, and quantitative polymerase chain reaction indicated that BMSCs and differentiation were unchanged between AFD-CGFs versus control groups (allp> 0.05). Alkaline phosphatase activity was higher in CGF groups (peaked at 14 d) than in the control group. Regarding thein vivoexperiments, four beagles were used for surgery and the rest as controls. Beagles were sacrificed at 2 weeks to observe acute response and membrane absorption; at 12 weeks for wound healing and chronic damage to the liver. According to general observations and histology, the CGFs of all groups were absorbed 2 weeks afterin vivoimplantation. No sign of intolerance was observed. Histology showed a slight increase in immune cells appearing in the implantation area after 2 weeks. However, no or very few inflammatory and immune cells were detected 3 months after the operation. Based on the hematoxylin and eosin staining and TEM results, the ultrastructure of the liver tissue was unchanged. In general, the results suggest that AFD-CGFs are biocompatible and may be a promising option for tissue healing.

Biomechanical evaluation of a customized 3D-printed polyetheretherketone condylar prosthesis.

The present study aimed to evaluate the biomechanical behavior of a custom 3D-printed polyetheretherketone (PEEK) condylar prosthesis using finite element analysis and mechanical testing. The Mimics software was used to create a 3D model of the mandible, which was then imported into Geomagic Studio software to perform osteotomy of the lesion area. A customized PEEK condyle prosthesis was then designed and the finite element model of the PEEK condyle prosthesis, mandible and fixation screw was established. The maximum stress of the prosthesis and screws, as well as stress and strain of the cortical and cancellous bones in the intercuspal position, incisal clench, left unilateral molar clench and right unilateral molar clench was analyzed. The biomechanical properties of the prosthesis were studied using two models with different lesion ranges. To simulate the actual clinical situation, a special fixture was designed. The compression performance was tested at 1 mm/min for the condyle prosthesis, prepared by fused deposition modeling (FDM). The results of a finite element analysis suggested that the maximum stress of the condyle was 10.733 MPa and the maximum stress of the screw was 9.7075 MPa; both were far less than the yield strength of the material. The maximum force that the two designed prostheses were able to withstand was 3,814.7±442.6 N (Model A) and 4,245.7±348.3 N (Model B). Overall, the customized PEEK condyle prostheses prepared by FDM exhibited a uniform stress distribution and good mechanical properties, providing a theoretical basis for PEEK as a reconstruction material for repairing the temporomandibular joint.

A novel vertical aligned mesoporous silica coated nanohydroxyapatite particle as efficient dexamethasone carrier for potential application in osteogenesis.

Bone defect is a common problem and inducing osteoblasts differentiation is the key process for the regenerative repair. Recently, the mesoporous silica (MS) coated nanohydroxyapatite (nHA) particles (nHA-MS) has shown enhanced intrinsic potency for bone regeneration, whereas whether the osteogenesis potency can be further enhanced after drug delivery has not been investigated. In this study, the nHA-MS was fabricated by a novel biphase stratification growth way. The cytotoxicity in MC3T3-E1 was validated by MTT assay, apoptosis analysis and cell cycle examination. The cell uptake was observed by confocal laser scanning microscope and transmission electron microscope respectively. After adsorption with dexamethasone (DEX), the osteogenic differentiation was determined bothin vitroandin vivo. The synthesized nHA-MS showed a core-shell structure that the nanorod-like nHA was coated by a porous MS shell (∼5 nm pores diameter, ∼50 nm thickness). A dose-dependent cytotoxicity was observed and below 10 µg ml-1was a safe concentration. The nHA-MS also showed efficient cell uptake efficiency and more efficient in DEX loading and release. After DEX adsorption, the nanoparticles exhibited enhanced osteogenic induction in MC3T3-E1 and rat calvarial bone defect regeneration. In conclusion, the nHA-MS is a favorable platform for drug delivery to obtain more enhanced osteogenesis capabilities.