Traumatic temporomandibular joint bony ankylosis in growing rats.

BACKGROUND: The pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis remains unknown. This study aimed to explore the pathogenesis of traumatic TMJ bony ankylosis in a rat model. METHODS: Twenty-four 3-week-old male Sprague-Dawley rats were used in this study. Excision of the whole disc, the fibrocartilage damage of the condyle and glenoid fossa, and narrowed joint space were performed in the left TMJ of the operation group to induce TMJ bony ankylosis (experimental side). The right TMJ underwent a sham operation (sham side). The control group did not undergo any operations. At 1, 4, and 8 weeks postoperatively, rats of the operation group were sacrificed and TMJ complexes were evaluated by gross observation, Micro-CT, histological examinations, and immunofluorescence microscopy. Total RNA of TMJ complexes in the operation group were analyzed using RNA-seq. RESULTS: Gross observations revealed TMJ bony ankylosis on the experimental side. Micro-CT analysis demonstrated that compared to the sham side, the experimental side showed a larger volume of growth, and a considerable calcified bone callus formation in the narrowed joint space and on the rougher articular surfaces. Histological examinations indicated that endochondral ossification was observed on the experimental side, but not on the sham side. RNA-seq analysis and immunofluorescence revealed that Matrix metallopeptidase 13 (MMP13) and Runt-related transcription factor 2 (RUNX2) genes of endochondral ossification were significantly more downregulated on the experimental side than on the sham side. The primary pathways related to endochondral ossification were Parathyroid hormone synthesis, secretion and action, Relaxin signaling pathway, and IL-17 signaling pathway. CONCLUSIONS: The present study provided an innovative and reliable rat model of TMJ bony ankylosis by compound trauma and narrowed joint space. Furthermore, we demonstrated the downregulation of MMP13 and RUNX2 in the process of endochondral ossification in TMJ bony ankylosis.

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.

Dentists' entrepreneurial intention and associated factors in public hospitals in major cities in Guangdong (South China): a cross-sectional study.

BACKGROUND: A rapid growth in private dentistry in China has been observed during recent years. Promoting the entrepreneurship of dentists has increasingly received attention in both dentistry and dental education worldwide. However, understanding about the unique features of entrepreneurial behaviors of dentists remains inadequate. METHODS: This study examines dentist's entrepreneurial intention (EI), which was represented by his/her intention of leaving the public hospital system to be engaged in the private sector. Through a snowball sampling method, a total of 336 questionnaires from public hospitals in five major cities in Guangdong Province (China) were collected. The association between the dentists' EI and their individual characteristics were analyzed using a logistic regression model. RESULTS: In the sample studied, 35.7% of the respondents reported to have EI. Female dentists are less likely to report EI (OR = 0.365, p = 0.001). Dentists in the age group of 36 to 45 years (OR = 14.205, p = 0.012) and those aged over 45 years (OR = 8.45, p = 0.066) reported respectively a much stronger EI than those in their 20s. Compared with intern dentists, attending dentists (OR = 7.812, p = 0.016) and associate/chief dentists (OR = 9.857, p = 0.021) were significantly more likely to report EI. Those with master level (OR = 0.221, p = 0.021) or doctorate degrees (OR = 0.118, p = 0.005) are much less likely to report EI. Meanwhile, those in mid-large hospitals (with 101-200 employees) (OR = 3.554, p = 0.036) and small hospitals (with < 50 employees) (OR = 2.398, p = 0.044) reported a stronger EI than those in large hospitals. Additionally, dentists' entrepreneurial behaviors, risk aversion attitudes and their family background all have significant associations. CONCLUSIONS: Since dentistry is a knowledge-intensive industry, dentists' entrepreneurial behaviors have their own features. The findings by this study suggest that, accumulation of practical skills in a dental career, as implied by age, professional qualifications and leadership skills, help to promote EI, whereas an academic oriented education degree per se does not. Dentists in mid-large and small hospitals, rather than in top large hospitals in China, have higher EI. Additionally, female dentists may need more social supports to develop a higher EI. These findings have practical implications for the promotion of EI among dentists.

The Past, Present, and Future of Dentoalveolar Surgery in China.

Dentoalveolar surgery, formerly known as dental surgery or oral surgery, is one of the basic branches of oral and maxillofacial surgery. While it has a long history; however, there are great differences in its evolution globally. This article presents a brief review on the development of dentoalveolar surgery internationally. Furthermore, a systematic review on its development in China, is detailed in 6 stages. However, while its development in China since 2005 has been most profound, improvements are still needed in treatment concepts, instruments, treatment processes, attention to high-risk populations and cooperation with other dental/medical disciplines. Future projections based on present standards of care are also presented.

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.

Alveolar ridge preservation with deproteinized bovine bone graft and collagen membrane and delayed implants.

To evaluate clinically and radiographically an alveolar ridge, preservation technique with deproteinized bovine bone graft and absorbable collagen membrane and then restoration with delayed implants were done. The study included 30 patients. The trial group's sockets were filled with deproteinized bovine bone graft (Bio-Oss) and covered with absorbable collagen membrane (Bio-Gide). The control group's sockets healed without any treatment. Panoramic radiograph and computed tomography were taken immediately after graft and 3 and 6 months later to evaluate the height, width, and volume change of the alveolar ridge bone. Dental implants were inserted in all sockets at 6 months, and osseointegration condition was evaluated in the following 12 months. All sockets healed uneventfully. In the trial group, the mean (SD) height reduction of the alveolar ridge bone was 1.05 (0.24) mm at 3 months and 1.54 (0.25) mm at 6 months. The width reduction was 1.11 (0.13) mm at 3 months and 1.84 (0.35) mm at 6 months. Bone volume reduction was 193.79 (21.47) mm at 3 months and 262.06 (33.08) mm at 6 months. At the same trend, in the control group, the bone height reduction was 2.12 (0.15) mm at 3 months and 3.26 (0.29) mm at 6 months. The width reduction was 2.72 (0.19) mm at 3 months and 3.56 (0.28) mm at 6 months. Bone volume reduction was 252.19 (37.21) mm at 3 months and 342.32 (36.41) mm at 6 months. There was a significant difference in alveolar ridge bone height, width, and volume reduction in the 2 groups. The osseointegration condition had no significant difference between the 2 groups. This study suggested that the deproteinized bovine bone graft and absorbable collagen membrane were beneficial to preserve the alveolar ridge bone and had no influence on the osseointegration of delayed implant.

Secondary healing after removal of large keratocystic odontogenic tumor in the mandible: enucleation followed by open packing of iodoform gauze.

PURPOSE: The aim of this retrospective study was to present the findings of an open packing method after enucleation of large keratocystic odontogenic tumors (KCOTs) in the mandible. PATIENTS AND METHODS: We performed a retrospective case series study of 27 patients with KCOTs larger than 5 cm treated at our institution between September 2003 and September 2008. A conservative surgical treatment was applied, which involved enucleation of the primary lesion and open packing of the residual osseous defect with iodoform gauze for secondary healing. Bone regeneration, tumor recurrence, and surgical complications were observed and analyzed. We used the χ(2) test and Pearson correlation coefficient for statistical analysis. RESULTS: The postoperative follow-up time was 52.3 months on average (range, 24 to 84 months). The packing gauze was changed every 2 weeks after enucleation, and the total duration for packing was 10.2 months on average (range, 7-15 months). Bone regeneration and satisfactory secondary healing were observed clinically and radiographically after treatment. Only 1 case had a recurrence 6 months after initial treatment, which was attributed to insufficient bony unroofing during enucleation. The recurrent lesion was re-treated by the same method, and no recurrence occurred in the following 6 years. No serious complications from this method of treatment were observed. No significant variables were found to be related to the recurrence. CONCLUSIONS: Enucleation with subsequent open packing was shown to be a conservative and comfortable treatment for patients and appears to be an effective choice for the management of large KCOTs in the mandible.

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.

Effect on implant drills and postoperative reactions for pre-extraction interradicular implant bed preparation during the COVID-19 pandemic and beyond.

The aim of the present study was to observe the abrasion of implant drills and postoperative reactions for the preparation of the interradicular immediate implant bed during the COVID-19 pandemic and beyond. Thirty-two implant drills were included in four groups: blank, improved surgery, traditional surgery, and control. In the improved surgery group, a dental handpiece with a surgical bur was used to decoronate the first molar and create a hole in the middle of the retained root complex, followed by the pilot drilling protocol through the hole. The remaining root complex was separated using a surgical bur and then extracted. Subsequently, the implant bed was prepared. Implant drills were used in the traditional surgery group to complete the decoronation, hole creation, and implant-drilling processes. The tooth remained intact until the implant bed was prepared. The surface roughness of the pilot drill was observed and measured. Surgery time, postoperative reactions (swelling, pain, and trismus), and fear of coronavirus disease 2019 scale (FCV-19S) were measured and recorded, respectively. Statistical analysis revealed significant difference with surface roughness among blank group (0.41 ± 0.05 µm), improved surgery group (0.37 ± 0.06 µm), traditional surgery group (0.16 ± 0.06 µm), and control group (0.26 ± 0.04 µm) (P < .001). Significant differences were revealed with surgery time between improved surgery group (5.63 ± 1.77 min) and traditional surgery group (33.63 ± 2.13 min) (P < .001). Swelling, pain, and trismus (improved group: r ≥ 0.864, P ≤ .006; traditional group: r ≥ 0.741, P ≤ .035) were positively correlated with the FCV-19S. This study proved that a new pilot drill could only be used once in traditional surgery but could be used regularly in improved surgery. Improved surgery was more effective, efficient, and economical than the traditional surgery. The higher FCV-19S, the more severe swelling, pain, and trismus.

Application of auriculotemporal nerve block and dextrose prolotherapy in exercise therapy of TMJ closed lock in adolescents and young adults.

BACKGROUND: Temporomandibular joint (TMJ) 'closed lock' is a clinical condition causing TMJ pain and limited mouth opening (painful locking). Recent studies suggest an increasing prevalence of degenerative joint disease associated with the onset of TMJ closed lock in adolescents and young adults. Early interventions are recommended, but the curative effect of standard therapies remains controversial. In this retrospective study, an alternative method of non-surgical treatment of TMJ closed lock is presented, and its long-term efficacy has been observed. METHODS: Forty adolescents and young adults, aged 16 to 30 years old, with distinct combination of symptoms of TMJ closed lock, were enrolled. Patients received anesthetic blockages of the auriculotemporal nerve, then performed mandibular condylar movement exercise for 10 min, and subsequently received hypertonic dextrose prolotherapy in retro-discal area of TMJ. Clinical assessments at baseline and at follow-up (2 weeks, 2 months, 6 months, and 5 years) included intensity and frequency of TMJ pain, mandibular range of motion, TMJ sounds, and impairment of chewing. RESULTS: Cone beam CT images of the TMJs revealed joint space changes in all patients and degenerative bone changes in 20% (8/40) of the patients. The patients were diagnosed as having disc displacement without reduction with limited opening. Successful reduction of displaced disc had been achieved in the treatment. And pain at rest and pain on mastication had substantially decreased in all patients and mandibular function and mouth opening had significantly improved since 2 weeks' follow-up. The overall success rate kept at a high level of 97.5% (39/40) at 6 months and 5 years' follow-up. CONCLUSIONS: The technique combining mandibular condylar movement exercise with auriculotemporal nerve block and dextrose prolotherapy is straightforward to perform, inexpensive and satisfactory to young patients with TMJ closed lock.

Cathepsin K deficiency promotes alveolar bone regeneration by promoting jaw bone marrow mesenchymal stem cells proliferation and differentiation via glycolysis pathway.

OBJECTIVES: To clarify the possible role and mechanism of Cathepsin K (CTSK) in alveolar bone regeneration mediated by jaw bone marrow mesenchymal stem cells (JBMMSC). MATERIALS AND METHODS: Tooth extraction models of Ctsk knockout mice (Ctsk-/- ) and their wildtype (WT) littermates were used to investigate the effect of CTSK on alveolar bone regeneration. The influences of deletion or inhibition of CTSK by odanacatib (ODN) on proliferation and osteogenic differentiation of JBMMSC were assessed by CCK-8, Western blot and alizarin red staining. To explore the differently expressed genes, RNA from WT and Ctsk-/- JBMMSC was sent to RNA-seq. ECAR, glucose consumption and lactate production were measured to identify the effect of Ctsk deficiency or inhibition on glycolysis. At last, we explored whether Ctsk deficiency or inhibition promoted JBMMSC proliferation and osteogenic differentiation through glycolysis. RESULTS: We found out that Ctsk knockout could promote alveolar bone regeneration in vivo. In vitro, we confirmed that both Ctsk knockout and inhibition by ODN could promote proliferation of JBMMSC, up-regulate expression of Runx2 and ALP, and enhance matrix mineralization. RNA-seq results showed that coding genes of key enzymes in glycolysis were significantly up-regulated in Ctsk-/- JBMMSC, and Ctsk deficiency or inhibition could promote glycolysis in JBMMSC. After blocking glycolysis by 3PO, the effect of Ctsk deficiency or inhibition on JBMMSC's regeneration was blocked subsequently. CONCLUSIONS: Our findings revealed that Ctsk knockout or inhibition could promote alveolar bone regeneration by enhancing JBMMSC regeneration via glycolysis. These results shed new lights on the regulatory mechanism of CTSK on bone regeneration.

Investigation of impacted permanent teeth except the third molar in Chinese patients through an X-ray study.

PURPOSE: To investigate the incidence and the local factors of impacted permanent teeth, except for the third molar, in Chinese patients through an x-ray study. MATERIALS AND METHODS: A total of 548 impacted permanent teeth from panoramic radiographs were studied and recorded according to the patients' gender and age, tooth position, and classification of impaction. The local factors contributing to impacted permanent tooth were also investigated. RESULTS: The incidence of impacted permanent teeth in the Chinese was 6.15%. The impacted tooth showed a predilection for women and was more common in the maxilla. The impaction of the canine had the greatest occurrence, 28.10% of all impacted teeth. Vertical impaction was most common (49.09%). The chief local factor for impacted teeth was the lack of interdental space (49.64%). CONCLUSIONS: All permanent teeth can occur with impaction in Chinese patients. Dentists should perform a thorough evaluation before planning suitable treatment.

Formation and in vitro/in vivo performance of "cortex-like" micro/nano-structured TiO2 coatings on titanium by micro-arc oxidation.

A novel "cortex-like" micro/nano dual-scale structured TiO2 coating was prepared on a titanium surface by micro-arc oxidation (MAO) with tetraborate electrolytes. This structure, which combines microslots with nanopores, exhibits super hydrophilicity. This coating modified the surface structure, chemistry, and hydrophilicity in a one-step treatment. Evolution of the coating together with its surface and structure properties was studied. We propose a forming mechanism of the dual-scale structure in which the oxides formed during the MAO discharge dissolve in the tetraborate electrolytes, leaving little or no deposition outside the discharge channels. We performed in vitro tests using human bone marrow-derived mesenchymal stem cells (hBMSCs) that compared this coating with a "volcano-like" MAO coating and a commercial sandblasted, large-grit and acid-etched (SLA) coating. The adhesion, morphology, proliferation, and differentiation of hBMSCs, together with the matrix mineralization, were investigated. Results suggest that the "cortex-like" structure significantly promotes the adhesion, spreading, and differentiation of cells and increases the matrix mineralization. In vivo tests with mongrel dogs showed an excellent osseointegration of the "cortex-like" coating. The combination of the dual-scale structure and the hydrophilicity of the "cortex-like" TiO2 coating synergistically resulted in an outstanding cytocompatibility and osseointegration, which may facilitate a higher level of implant success.

Early osseointegration of implants with cortex-like TiO2 coatings formed by micro-arc oxidation: A histomorphometric study in rabbits.

In our previous studies, a novel cortex-like TiO2 coating was prepared on Ti surface through micro-arc oxidation (MAO) by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment were testified. This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration. A sand-blasting and acid-etching (SLA) coating that has been widely used in clinical practice served as control. Topographical and chemical characterizations were conducted by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, contact angle meter, and step profiler. Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic, whereas the SLA surface was hydrophobic. The roughness of MAO was similar to that of SLA. The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT, histological analysis, and fluorescent labeling at the bone-implant interface four weeks after surgery. The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation. Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces. It was suggested that with micro/nanostructure and superhydrophilicity, the cortex-like MAO coating causes excellent osseointegration, holding a promise of an application to implant modification.

Influence of preservation of the alveolar ridge on delayed implants after extraction of teeth with different defects in the buccal bone.

Our aim was to evaluate the influence of preservation of the alveolar ridge on delayed implants with different defects in the buccal bone. We enrolled 60 patients who had one posterior mandibular tooth extracted. Cone-beam computed tomography (CT) was used to measure the buccal bone defects in the alveolar ridge before the tooth was extracted (level A=3 to 5 mm, and level B=more than 5 mm). After the tooth had been extracted, the socket either had the alveolar ridge preserved (trial group) or it was left to heal spontaneously (control group). The changes in the dimensions of the alveolar ridge from preoperatively to 6 months postoperatively were evaluated by cone-beam CT. Suitable implants were inserted 6 months later, and their length and diameter recorded. The implant stability quotient was evaluated for the following 3 months. The dimensions of the bone in the alveolar ridge in the trial group were significantly less than those in the control groups in both levels. Fifty-seven patients required implants (except 3 in level B in the control group). There were more longer and wider implants in the trial group than in the control group in Level B. 3 months after implantation, there were no significant differences in implant stability quotients between the groups, though in the control group, Level B, the mean (SD) value was 69.50 (1.00) while in the other groups values were all above 70 at 3 months. We conclude that when the defect in the buccal bone was more than 5mm, the alveolar ridge preservation demonstrated a remarkable effect in preserving the alveolar ridge dimension and delayed implantation.

Substance P incorporation in calcium phosphate cement for dental alveolar bone defect restoration.

A combination of osteoinductive neuropeptide substance P (SP) and osteoconductive bone cement of calcium phosphate (CPC) might provide an effective and lower-cost solution for complex alveolar bone defects restoration. The present study aims to investigate the key design considerations of SP delivery in CPC. In this study, CPC-based modular scaffolds were developed, where collagen type I was used as accessory organic ingredient to modulate the physical and biological characters. SP was directly mixed in the cement as free peptides, or was covalently immobilized with collagen component. The structural and mechanical properties of the scaffolds were assessed in vitro, and their osteogenic ability was observed in a rabbit model with alveolar bone defect. The results showed that SP could enhance the osteo-conductivity/inductivity of CPC. Collagen solution optimized biocompatibility of CPC, and meanwhile exhibited additive effects on the functions of SP. Nevertheless, immobilization of SP with collagen blocked their bioactivity in CPC. Collagen sponges created macro-porosity in CPC and achieved maximum bone ingrowth with the aid of SP. In conclusion, the present study primarily demonstrated that CPC scaffold can be functionalized by synthetic SP, and the biocompatibility and porosity of the scaffold are adaptable key factors determining their final osteogenic activities.

Thorough documentation of the accidental aspiration and ingestion of foreign objects during dental procedure is necessary: review and analysis of 617 cases.

OBJECTIVES: To review the cases of accidental aspiration and ingestion of foreign objects during dental procedure, and to emphasize the importance of thorough documentation of the accidents. METHODS: A comprehensive search on (dental procedure/treatment/practice), (aspiration/inhalation), and (ingestion/swallow) was performed for all years before 1st October 2014 available. The statistic analysis was made on the variables including journals and reported year, patients' age, gender, general conditions, dental procedure and location for procedure, foreign objects, site of involvement, possible causes, anesthesia during procedure and treatment, symptoms, treatment time and treatment modality, follow-up, and so on. RESULTS: A total of 617 cases reported by 45 articles from 37 kinds of journals were included and analyzed. Most reports made detailed record. While some important variables were recorded incompletely, including patient's general conditions, location for procedure, clinical experience of the involving dentists, tooth position of procedure, possible causes, and anesthesia during procedure and treatment for the accident. CONCLUSIONS: Aspiration and ingestion of foreign objects are rare and risky complication during dental procedure. Each accident should have thorough documentation so as to provide enough information for the treatment and prevention.

Evaluation of reference gene suitability for quantitative expression analysis by quantitative polymerase chain reaction in the mandibular condyle of sheep.

Reference genes are commonly used as a reliable approach to normalize the results of quantitative polymerase chain reaction (qPCR), and to reduce errors in the relative quantification of gene expression. Suitable reference genes belonging to numerous functional classes have been identified for various types of species and tissue. However, little is currently known regarding the most suitable reference genes for bone, specifically for the sheep mandibular condyle. Sheep are important for the study of human bone diseases, particularly for temporomandibular diseases. The present study aimed to identify a set of reference genes suitable for the normalization of qPCR data from the mandibular condyle of sheep. A total of 12 reference genes belonging to various functional classes were selected, and the expression stability of the reference genes was determined in both the normal and fractured area of the sheep mandibular condyle. RefFinder, which integrates the following currently available computational algorithms: geNorm, NormFinder, BestKeeper, and the comparative ΔCt method, was used to compare and rank the candidate reference genes. The results obtained from the four methods demonstrated a similar trend: RPL19, ACTB, and PGK1 were the most stably expressed reference genes in the sheep mandibular condyle. As determined by RefFinder comprehensive analysis, the results of the present study suggested that RPL19 is the most suitable reference gene for studies associated with the sheep mandibular condyle. In addition, ACTB and PGK1 may be considered suitable alternatives.

Human embryonic stem cell-derived mesenchymal stem cell seeding on calcium phosphate cement-chitosan-RGD scaffold for bone repair.

Calcium phosphate cement (CPC) has in situ-setting ability and excellent osteoconductivity. Human embryonic stem cells (hESCs) are exciting for regenerative medicine due to their strong proliferative ability and multilineage differentiation capability. However, there has been no report on hESC seeding with CPC. The objectives of this study were to obtain hESC-derived mesenchymal stem cells (hESCd-MSCs), and to investigate hESCd-MSC proliferation and osteogenic differentiation on novel CPC with chitosan immobilized with RGD (CPC-chitosan-RGD). RGD was covalently bonded with chitosan, which was then incorporated into CPC. The CPC-chitosan-RGD scaffold had higher strength and toughness than CPC-chitosan control without RGD (p<0.05). hESCs were cultured to form embryoid bodies (EBs), and the MSCs were then migrated out of the EBs. Flow cytometry indicated that the hESCd-MSCs expressed typical surface antigen profile of MSCs. hESCd-MSCs had good viability when seeded on CPC scaffolds. The percentage of live cells and the cell density were significantly higher on CPC-chitosan-RGD than CPC-chitosan control. Scanning electron microscope examination showed hESCd-MSCs with a healthy spreading morphology adherent to CPC. hESCd-MSCs expressed high levels of osteogenic markers, including alkaline phosphatase, osteocalcin, collagen I, and Runx2. The mineral synthesis by the hESCd-MSCs on the CPC-chitosan-RGD scaffold was twice that for CPC-chitosan control. In conclusion, hESCs were successfully seeded on CPC scaffolds for bone tissue engineering. The hESCd-MSCs had good viability and osteogenic differentiation on the novel CPC-chitosan-RGD scaffold. RGD incorporation improved the strength and toughness of CPC, and greatly enhanced the hESCd-MSC attachment, proliferation, and bone mineral synthesis. Therefore, the hESCd-MSC-seeded CPC-chitosan-RGD construct is promising to improve bone regeneration in orthopedic and craniofacial applications.