Osteogenic potential of three different autogenous bone particles harvested during implant surgery.

OBJECTIVES: The aim was to compare the osteoblast activity and osteogenic potential of autogenous bone particles harvested using three different techniques and determine the most advantageous method of collecting autogenous bone particles. SUBJECTS AND METHODS: Bone particles were harvested from 20 patients during dental implant surgery using bone scraping, low-speed drilling and bone trap filtering. After the osteoblasts were cultured, cell proliferation, migration, mineralization, transcription of osteogenesis-related genes, secretion of osteogenesis-related proteins and osteoinductive protein content in the bone particle matrix were evaluated. RESULTS: Osteoblast activity and osteogenic potential were higher in bone samples harvested by scraper or low-speed drilling than in samples harvested by bone trap filter. Although these parameters were slightly lower in the low-speed drilling group than in the scraper group, significant differences were found only in bone Gla protein levels. However, the levels of osteoinductive proteins in the bone particle matrix were significantly higher in the low-speed drilling group than in the scraper group. CONCLUSIONS: Low-speed drilling is a recommendable and effective technique for collecting autogenous bone particles. In implant operations, low-speed drilling can be considered the first-line option, and if the quantity of harvested bone is insufficient, bone shavings obtained by the scraper may be considered.

Clinical evaluation of salivary carbohydrate antigen 125 and leptin in controls and parotid tumours.

OBJECTIVES: We determined the correlation between saliva and serum for CA125 and leptin, and evaluated their clinical screening potential for parotid tumours. SUBJECTS AND METHODS: Serum, acid-stimulated bilateral parotid saliva and chewing-stimulated whole saliva were collected and measured the levels of CA125 and leptin with electrochemiluminescence immunoassay and enzyme-linked immunosorbent assay for healthy controls and patients with unilateral parotid tumour. Intra- and intergroup comparisons were made among them. Correlations and receiver operating curve analyses were also conducted. RESULTS: There was no correlation between salivary and serum CA125 (r = -0.157-0.265, P > 0.05), while significant correlation was found for leptin (r = 0.219-0.761, P < 0.05). Leptin levels in tumour parotid saliva and CA125 levels in whole saliva were elevated significantly (P < 0.001) and showed screening potential for parotid tumours. Salivary and serum leptin levels were significantly higher in women than in men (P < 0.001). CONCLUSIONS: Salivary CA125 might originate primarily from salivary gland and tumour rather than from blood, while salivary leptin might originate from both blood and salivary gland. Multiple sources might contribute to the significantly elevated CA125 in whole saliva. Whole saliva CA125 and parotid saliva leptin reflected the occurrence of parotid tumours, while serum CA125 and leptin did not. Salivary CA125 and leptin could not distinguish malignant parotid tumours. When detecting leptin level, the influence of subjects' sex must be considered.

[Development and application of homeostatic medicine in stomatology].

Homeostatic medicine is the science of studying the balance of molecules, cells, tissues, organs as well as the whole of the organism, and it is a comprehensive discipline based on the maintenance of balance for the promotion of health, prevention and treatment of diseases. The introduction of homeostatic medicine is of great significance for the development of dentistry. Through the study of oral homeostasis, it helps to elucidate the intrinsic mechanism of disease occurrence fundamentally based on a unique perspective, which is expected to provide effective solutions for clinical diseases and impetus for continuous progress in the development of medicine, and to point out the direction for the developments of science and technology in the future.

DPSCs regulate epithelial-T cell interactions in oral submucous fibrosis.

BACKGROUND: Oral submucous fibrosis (OSF) is a precancerous lesion characterized by fibrous tissue deposition, the incidence of which correlates positively with the frequency of betel nut chewing. Prolonged betel nut chewing can damage the integrity of the oral mucosal epithelium, leading to chronic inflammation and local immunological derangement. However, currently, the underlying cellular events driving fibrogenesis and dysfunction are incompletely understood, such that OSF has few treatment options with limited therapeutic effectiveness. Dental pulp stem cells (DPSCs) have been recognized for their anti-inflammatory and anti-fibrosis capabilities, making them promising candidates to treat a range of immune, inflammatory, and fibrotic diseases. However, the application of DPSCs in OSF is inconclusive. Therefore, this study aimed to explore the pathogenic mechanism of OSF and, based on this, to explore new treatment options. METHODS: A human cell atlas of oral mucosal tissues was compiled using single-cell RNA sequencing to delve into the underlying mechanisms. Epithelial cells were reclustered to observe the heterogeneity of OSF epithelial cells and their communication with immune cells. The results were validated in vitro, in clinicopathological sections, and in animal models. In vivo, the therapeutic effect and mechanism of DPSCs were characterized by histological staining, immunohistochemical staining, scanning electron microscopy, and atomic force microscopy. RESULTS: A unique epithelial cell population, Epi1.2, with proinflammatory and profibrotic functions, was predominantly found in OSF. Epi1.2 cells also induced the fibrotic process in fibroblasts by interacting with T cells through receptor-ligand crosstalk between macrophage migration inhibitory factor (MIF)-CD74 and C-X-C motif chemokine receptor 4 (CXCR4). Furthermore, we developed OSF animal models and simulated the clinical local injection process in the rat buccal mucosa using DPSCs to assess their therapeutic impact and mechanism. In the OSF rat model, DPSCs demonstrated superior therapeutic effects compared with the positive control (glucocorticoids), including reducing collagen deposition and promoting blood vessel regeneration. DPSCs mediated immune homeostasis primarily by regulating the numbers of KRT19 + MIF + epithelial cells and via epithelial-stromal crosstalk. CONCLUSIONS: Given the current ambiguity surrounding the cause of OSF and the limited treatment options available, our study reveals that epithelial cells and their crosstalk with T cells play an important role in the mechanism of OSF and suggests the therapeutic promise of DPSCs.

[Overview on diagnosis and treatment of oral diseases in the Qing Royal Court].

The remained documents and archives show that the history of diagnosis and treatment of oral diseases in royal court of the Qing Dynasty was over 200 years. The departmental system of medical care in the Qing Royal Court was inherited from former Ming Dynasty. Although the departments in the system changed over reigns, the Department of Dentistry exist all the time. In a set of historical records of 38 medical cases opened to the public, the documented symptoms and diseases, in the sense of modern medical science, included periodontitis, oral mucosal diseases, dental caries, parotiditis, etc., and the patients involved various ranks in the court, showing that oral diseases were common in the Qing Royal Court. The royal doctors ranked variedly and the medication they used was diverse. Medical fuming or steaming and medical heating were some distinctive methods among the treatments. In 1600s, the western modern medical science started to be introduced into China. In the reign of Kangxi Emperor (1700s), many western doctors were employed by the royal court and they engaged in the treatment of oral diseases. The late Qing Dynasty appeared the second peak that western doctors came into China. In 1898, Dr. Jingrong Chen, a dentist who possessed knowledge of modern dentistry in Beijing city, set up a dental clinic in the royal court and gave treatment to patients in the royal members and high-ranking officials.

[Effect of hydroxyapatite based agents on the bonding properties of universal adhesives].

Objective: To study the effect of hydroxyapatite (HA) based agents on the bonding properties of universal adhesive with different application modes, and to provide evidence for the use of adhesives after desensitization treatment. Methods: Sixty impacted third molars were extracted and selected (acquired from Department of Oral and Maxillofacial Surgery, College of Stomatology, Xi'an Jiaotong University). Four third molars were used to prepare 1 mm thick dentin disks and treated with 1% citric acid to simulate sensitive tooth models. The dentin surfaces were observed by scanning electron microscope (SEM) after treating with no desensitization (control group), desensitized by HA based toothpaste Biorepair and Dontodent Sensitive respectively (desensitizing toothpaste A group and B group), or HA paste treatment (desensitizing paste group ) (n=2 per group). The remaining teeth were selected to expose the mid-coronal dentin and establish dentin sensitivity models. Then, the specimens were divided into 4 former groups and received corresponding treatment. Each group was randomly divided into 2 subgroups, and intermediately strong universal adhesive (G-Premio Bond) was applied on the desensitized dentin by either etch-and-rinse mode or self-etch mode. Resin-dentin slice specimens (n=4 per subgroup), microtensile specimens (n=20 per subgroup) and slice specimens (n=6 per subgroup) were prepared. The microstructure and nanoleakage of the adhesive interfaces were observed by scanning electron microscopy (SEM). The microtensile strength (bond strength) and fracture mode were tested and recorded. The water permeability of the adhesive interface was observed by laser scanning confocal microscopy (LSCM). Results: SEM showed that desensitizing toothpaste and desensitizing paste could partially or entirely occlude most of the dentin tubules. For the etch-and-rinse mode, the bond strength of specimens treated with toothpaste A [(40.98±4.60) MPa], toothpaste B [(40.89±4.64) MPa] and HA paste [(41.48±3.65) MPa] was significantly higher than that of the control group [(38.58±4.28) MPa] (F=3.89,P<0.05). There was no statistically significant difference in bond strength among the 4 subgroups for self-etch modes (F=0.48,P>0.05). After desensitization, the bond strength of the control group and desensitizing groups in the self-etch mode was significantly higher than that in the etch-and-rinse mode (P<0.05). The overall fracture modes were mixed failure and interfacial failure in the control group and desensitizing groups. SEM showed speckled silver-stained particles deposited along the bottom of the hybrid layer on the bond interface of etch-and-rinse mode, and there were few silver-stained particles deposited on the bond interface of self-etch mode. LSCM showed continuous linear penetration in the hybrid layer of etch-and-rinse mode subgroups and discontinuous linear penetration in the hybrid layer of self-etch mode subgroups. Conclusions: HA based desensitizers have no adverse effect on the bond strength of intermediately strong universal adhesive and show good bonding performance accompanied with the self-etch mode.

[Osteoradionecrosis and bisphosphonate-related osteonecrosis of the jaw: a review of the pathogenesis and treatment].

Osteoradionecrosis of the jaw (ORNJ) and bisphosphonate-related osteonecrosis of the jaw (BRONJ) are usually caused by head and neck radio-therapy and by the usage of bisphosphonate, respectively. These diseases can lead to facial deformity and dysfunction of the mandible, and may cause severe chronic facial pain. The pathogenesis of ORNJ and BRONJ are complex, and the therapy of which is still challenged. The present article reviewed the latest literature about the pathogenesis and treatment of ORNJ and BRONJ were reviewed for update. The irradiation may damage the endothelia cells and microvessels in jaw bone, which leads to the termination of the bone remodeling 15 days after irradiation. Mesenchymal stem cells based bio-therapy can assist the recovery of mandibular circulation and the reconstruction of the bone, showing therapeutic potential for ORNJ clinical treatment. Bisphosphonate can induce the dysfunction of bone marrow mesenchymal stem cells and the immune imbalance of the body. Allogeneic mesenchymal stem cells transplantation can rebuild the jaw bone and rebalance the immune of the recipient, demonstrating the ideally potential for the treatment of BRONJ. Taking together, although it would be complicated and winding, the improvement of biotech and the usage of mesenchymal stem cells shed a light on the way of ORNJ and BRONJ treatments.

[Evaluation of the effects auricular reconstruction with Medpor combined with hearing rehabilitation].

Objective: To investigate the clinical effects of single-stage auricular reconstruction and hearing rehabilitation in children with microtia and external auditory canal atresia. Methods: Sixty eight cases of microtia with external auditory canal atresia (53 males and 15 females, age from 7 to 12 years, with a median age of 8.8 years), who received operations in Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine from July 2017 to December 2019 were collected.A total of 28 cases received auricle reconstruction with high-density polyethylene (Medpor) framework and hearing reconstructions, among which 20 patients received the traditional external auditory canal and middle ear repair (EACR), and eight patients were implanted bone conduction device bone bridge(BB) simultaneously.In the control group, 40 patients only received Medpor frame implantation for auricle plasty. Postoperative changes in auricle morphology and auditory function and postoperative complications were evaluated. Results: After three to thirty months follow-ups, the auricles shape recovered well in all three groups. The average scores of 14 fine structures in the auricles were 9.43(EACR) and 10.67(BB) points. The average score of auricle symmetry were 6.83(EACR) and 6.00(BB) points. There was no significant difference compared to the auricle reconstruction group (8.23/6.20 points). P>0.05. After surgery, the average hearing improvement in the BB group was 43.33 dB HL and the average speech recognition threshold declined 42.28 dB HL. In the EACR group, the average hearing improvement was 4.13 dB HL and the average speech recognition threshold declined 11.36 dB HL. No vertigo, tinnitus, cerebrospinal fluid leakage and other complications occurred in all the patients. In the EACR group, sensorial hearing loss, auricle stent fracture, ear canal restenosis and ear canal atresia occurred in one patient respectively. In the auricle group, one auricle stent exposure and one facial branch nerve injury occurred. Nearly ten patients had difficulty in hair growth at scalp incisions. Conclusions: The operation of single-stage auricular reconstruction and hearing rehabilitation for microtia is feasible. The methods of hearing reconstruction should be determined by evaluating the development of the inner and middle ear of the patients. For those with poor mastoid development, bone bridge implantation is recommended to achieve a stable and significant hearing effect.

[The pattern and regulatory mechanism of mammalian diphyodont tooth replacement].

Although the dental lamina of permanent teeth in human being has been developed as early as the embryo stage, the replacement of the deciduous teeth by permanent teeth does not take place untill the age of 6 to 12 years old. The molecular mechanism of the initiation of permanent teeth is still unclear. The rodent species are usually used for the tooth development research in the past. However, this animal model is not suitable for the tooth replacement study because of the absence of tooth replacement in rodents. After 10 years of efforts, our team has established the animal model of miniature pig for tooth replacement research. Using this model, we firstly defined the spatiotemporal pattern of teeth replacement. In the further mechanism research, results showed that the growing rate of the deciduous teeth was faster than that of the surrounding alveolar bone, and biomechanical stress inside mandible was generated due to the fast growth of deciduous teeth. The stress might up-regulate the signal of Runt-related transcription factor 2 (RUNX2)-Wnt pathway in the mesenchyme between the deciduous and permanent teeth, sustain the successional dental lamina at the resting stage and inhibit the development of permanent teeth. A similar expression pattern was also found in the mesenchyme between the deciduous and permanent teeth in human. Our findings demonstrated that the eruption of deciduous tooth released the stress inside mandible, thus induced the "Wnt translocation" from the mesenchyme into the epithelium of permanent counterpart and therefore initiated the development of permanent teeth. The underlying mechanism of the replacement of deciduous teeth by permanent teeth is the regulation of biomechanical stress throughout the initiation process. Based on the findings, we proposed the theory of "biomechanical stress regulation of the tooth replacement" . The replacement pattern and regulatory mechanism provide a scientific foundation for the organ development and regeneration by regulating the biomechanical stress and Wnt pathway in the future.

[Nitrate: a pioneer from the mouth to the systemic health and diseases].

Dietary nitrate which mainly comes from green leafy vegetables, is absorbed into blood circulation by the intestinal mucosa. Parotid gland is an important organ for transporting nitrate. Nitrate in blood is taken up by sialin, a nitrate transporter and concentrated in salivary glands and secreted into saliva. The salivary nitrate is partially reduced to nitrite and nitric oxide by oral bacteria, and then salivary nitrate and nitrite return into blood circulation with swallowing and intestinal mucosal absorption. As a non-classic source of nitric oxide, nitrate-nitrite-nitric oxide pathway plays an important role on physiological and pathological conditions, especially on the condition of hypoxia and ischemia. These functions include body protection, such as gastrointestinal tract, cardiovascular system, anti-inflammation, regulation of glucose/lipid metabolism, improvement of sport ability, maintaining gut microbiome hemostasis, and alleviating senility. The traditional view on nitrate as a harmful substance to human body has been proved to be lack of scientific evidence. With further research and application, as a pioneer from the mouth to the whole body, nitrate is expected to play a crucial part in human health, and prevention and treatment of systemic diseases.

Temporal and spatial expression of TGF-beta2 in tooth crown development in mouse first lower molar.

Transforming Growth Factor beta2 (TGF-beta2) is involved in the regulation of many important cellular processes during tooth development. In this study we systematically characterized the expression pattern of TGF-beta2 in vivo and further analyzed its possible roles during different developmental stages of mouse first lower molar using immunofluorescence histochemical method with confocal microscopy. TGF-beta2 signaling was detected in different developing stages in both dental epithelium and surrounding dental mesenchyme. For the first time, we found that the basement membrane and epithelial cells in the basal layer showed no immunostaining from embryonic day 11 to 13; the primary enamel knot and secondary enamel knot exhibited pronounced immunostaining with different expression patterns at embryonic day 14 and 16. In addition, the mature ameloblast lost immunoreactivity, but the secretory ameloblast still exhibited positive immunoreaction at day 2 of postnatal development. Collectively, the temporospatial distribution patterns of TGF- beta2, especially in the basement membrane, epithelial cells in the basal layer, enamel knot, mature odontoblast and ameloblast, suggested a close association between TGF-beta2 signaling and tooth crown development, and indicated that TGF-beta2 might participate in tooth initiation, epithelial morphogenesis, formation of dentine matrix, and ameloblast differentiation.

Bone marrow cells can give rise to ameloblast-like cells.

Post-eruptive loss of ameloblasts requires identification of alternative sources for these cells to realize tooth-tissue-engineering strategies. Recent reports showed that bone-marrow-derived cells can give rise to different types of epithelial cells, suggesting their potential to serve as a source for ameloblasts. To investigate this potential, we mixed c-Kit(+)-enriched bone marrow cells with embryonic dental epithelial cells and cultured them in re-association with dental mesenchyme. Non-dividing, polarized, and secretory ameloblast-like cells were achieved without cell fusion. Before basement membrane reconstitution, some bone marrow cells migrated to the mesenchyme, where they exhibited morphological, molecular, and functional characteristics of odontoblasts. These results show, for the first time, that bone-marrow-derived cells can be reprogrammed to give rise to ameloblast-like cells, offering novel possibilities for tooth-tissue engineering and the study of the simultaneous differentiation of one bone marrow cell subpopulation into cells of two different embryonic lineages.

The inhibitory effect of magnolol from Magnolia officinalis on glucosyltransferase.

Dental caries has been an intractable disease in spite of intense dental research. Glucosyltransferase (GTF) enzyme plays the most important role in the development of dental caries. In our previous studies, magnolol, a compound from Magnolia officinalis Rehder et Wilson (Magnoliaceae), was shown to possess a strong anti-GTF activity. The purpose of the present study was to examine the effect of magnolol on the functional domains of GTF for the purpose of defining its anti-GTF activity mechanism. GTF-I which was prepared from Streptococcus milleri transformant KSB8 cells expressing the gtfB gene was used. The results demonstrated magnolol reduced total glucan synthesis, depending on the magnolol concentration. There were no significant differences in Michaelis constant (K(m)) values between the presence and absence of magnolol as determined by Lineweaver-Burk plot, and maximum velocity (V(m)) in the presence of magnolol was lower than that in its absence. Magnolol significantly inhibited both sucrose hydrolysis and glucosyl transfer to glucan by GTF-I. Free glucose in the presence of magnolol was reduced by 33-48% as compared to in its absence, while the quantity of glucan was reduced by 75-82%. These findings suggested that magnolol inhibited both two sequential reaction phases of GTF non-competitively by operating on the glucan-binding domain, but not on the catalytic domain. Magnolol could be a valuable resource for the exploration of novel bioactive compounds in natural products.

Spatial and temporal expression of histone demethylase, Kdm2a, during murine molar development.

The histone demethylase, lysine (K)-specific demethylase 2A (Kdm2a), is highly conserved and expressed ubiquitously. Kdm2a can regulate cell proliferation and osteo/dentinogenic, adipogenic and chondrogenic differentiation of mesenchymal stem cells (MSCs) derived from dental tissue. We used quantitative real-time RT-PCR analysis and immunohistochemistry to detect Kdm2a expression during development of the murine molar at embryonic days E12, E14, E16 and E17 and postnatal days P3 and P14. Immunohistochemistry results showed no positive staining of Kdm2a at E12. At E14, Kdm2a was expressed weakly in the inner enamel epithelium, stellate reticulum cells and dental sac. At E16, Kdm2a was expressed mainly in the inner and outer enamel epithelium, stratum intermedium and dental sac, but weaker staining was found in cervical loop and dental papilla cells adjacent to the basement membrane. At E17, the strongest Kdm2a staining was detected in the ameloblasts and stronger Kdm2a staining also was detected in the stratum intermedium, outer enamel epithelium and dental papilla cells compared to the expression at E16. Postnatally, we found that Kdm2a was localized in secretory and mature ameloblasts and odontoblasts, and dentin was unstained. Real-time RT-PCR showed that Kdm2a mRNA levels in murine germ cells increased from E12 to E14 and from E14 to E16; no significant change occurred at E16, E17 or P3, then the levels decreased at P14 compared to P3. Kdm2a expression may be closely related to cell proliferation, to ameloblast and odontoblast differentiation and to the secretion of extracellular enamel and dentin during murine tooth development.

[Preliminary analysis of influencing factors on source of snoring sound].

Objective:To investigate the main factors affecting the source of snoring sound of snoring patients.Method:Seventy-three patients with either simple snoring or obstructive sleep apnea-hypopnea syndrom(AHI≤40) underwent routine ENT examination,CT scanning(in awake condition) and drug-induced sleep endoscopy.The sources of snoring sound were observed.The neck circumference,body mass index and CT data were measured.Result:The sources of snoring sound of the 73 cases were divided into three types in general: palatal fluttering based group(Group Ⅰ),lateral wall vibration based group(Group Ⅱ) and palatal fluttering together with vibration of lateral wall based group(Group Ⅲ).The minimum lateral caliber of retropalatal region and retroglossal region,the ratio of minimum anteroposterior/ lateral caliber of the two regions,the thickness of pharyngeal lateral wall had statistical differences.The main influencing factors on the source of snoring sound between Group Ⅱ and Group Ⅰ were the ratio of minimum anteroposterior/lateral caliber of retropalatal region and the mean thickness of pharyngeal lateral wall.The influencing factor between Group Ⅲ and Group Ⅰ was the mean thickness of pharyngeal lateral wall.Conclusion:The ratio of minimum anteroposterior/lateral caliber of retropalatal region and the mean thickness of pharyngeal lateral wall are the main factors affecting the source of snoring sound of snoring patients.

From Nitrate to Nitric Oxide: The Role of Salivary Glands and Oral Bacteria.

The salivary glands and oral bacteria play an essential role in the conversion process from nitrate (NO3-) and nitrite (NO2-) to nitric oxide (NO) in the human body. NO is, at present, recognized as a multifarious messenger molecule with important vascular and metabolic functions. Besides the endogenous L-arginine pathway, which is catalyzed by complex NO synthases, nitrate in food contributes to the main extrinsic generation of NO through a series of sequential steps (NO3--NO2--NO pathway). Up to 25% of nitrate in circulation is actively taken up by the salivary glands, and as a result, its concentration in saliva can increase 10- to 20-fold. However, the mechanism has not been clearly illustrated until recently, when sialin was identified as an electrogenic 2NO3-/H+ transporter in the plasma membrane of salivary acinar cells. Subsequently, the oral bacterial species located at the posterior part of the tongue reduce nitrate to nitrite, as catalyzed by nitrate reductase enzymes. These bacteria use nitrate and nitrite as final electron acceptors in their respiration and meanwhile help the host to convert nitrate to NO as the first step. This review describes the role of salivary glands and oral bacteria in the metabolism of nitrate and in the maintenance of NO homeostasis. The potential therapeutic applications of oral inorganic nitrate and nitrite are also discussed.

Bio-Root and Implant-Based Restoration as a Tooth Replacement Alternative.

We previously reported that dental stem cell-mediated bioengineered tooth root (bio-root) regeneration could restore tooth loss in a miniature pig model. As a potential new method for tooth restoration, it is essential to compare this method with the widely used commercial dental implant-based method of tooth restoration. Tooth loss models were created by extracting mandibular incisors from miniature pigs. Allogeneic periodontal ligament stem cells (PDLSCs) and dental pulp stem cells (DPSCs) were isolated and cultured. A PDLSC sheet was prepared by adding 20.0 µg/mL vitamin C to the culture medium; in addition, a hydroxyapatite tricalcium phosphate (HA/TCP)/DPSC graft was fabricated and cultured in a 3-dimensional culture system. A total of 46 bio-root implantations and 9 dental implants were inserted, and crown restorations were performed 6 mo after implantation. Histological, radiological, biomechanical, and elemental analyses were used to evaluate and compare tissue-engineered bio-roots and dental implants to the natural tooth roots. After 6 mo, both computed tomography scans and histological examinations showed that root-like structures and dentin-like tissues had formed. Three months after crown restoration, clinical assessments revealed that tooth function was equivalent in the regenerated bio-root and the dental implant. Biomechanical testing showed that the bio-roots were similar to natural tooth roots in compressive strength, modulus of elasticity, and torsional force; however, these properties were significantly higher in the dental implants. Elemental analysis revealed a higher similarity in elemental composition between bio-roots and natural tooth roots than between bio-roots and dental implants. However, the dental implant success rate was 100% (9 of 9) and the bio-root success rate was only 22% (10 of 46). Taken together, we showed that an allogeneic HA/TCP/DPSC/PDLSC sheet could successfully build a bio-root with structure and function similar to the natural tooth root; however, tissue engineering procedures must be optimized further to improve the success rate.

Dynamic compression combined with exogenous SOX-9 promotes chondrogenesis of adipose-derived mesenchymal stem cells in PLGA scaffold.

OBJECTIVE: Mechanical stimuli play a crucial role in cartilage repair and regeneration. Dynamic compression, as a physical stimulus, has been demonstrated to be an important factor in regulating the proliferation and differentiation of adipose-derived mesenchymal stem cells (ADSCs). However, the interaction of mechanical stimuli and chondrogenesis regulator on the chondrocyte phenotype and differentiation of ADSCs remains unknown. In the present study, we investigated the effects of dynamic compression combined with exogenous SOX-9 on chondrogenesis of ADSCs in a three-dimensional porous polylactic-co-glycolic acid (PLGA) scaffold. MATERIALS AND METHODS: The morphology of ADSCs on the scaffolds was examined using scanning electron microscopy (SEM). The proliferation of ADSCs was evaluated by MTT assay. The expression of cartilage-specific genes in early chondrogenic differentiation was assessed by real-time PCR. RESULTS: Our results indicated that the combination of dynamic compression with exogenous SOX-9 induces the expression of chondrogenic genes and promotes the proliferation of ADSCs. CONCLUSIONS: Therefore, compression and SOX-9 have positive effects on chondrogenesis process of ADSCs, which may benefit articular cartilage regeneration.

Mesenchymal dental pulp cells attenuate dentin resorption in homeostasis.

Dentin in permanent teeth rarely undergoes resorption in development, homeostasis, or aging, in contrast to bone that undergoes periodic resorption/remodeling. The authors hypothesized that cells in the mesenchymal compartment of dental pulp attenuate osteoclastogenesis. Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells [DPCs]) and alveolar bone (alveolar bone cells [ABCs]) were isolated and separately cocultured with primary rat splenocytes. Primary splenocytes readily aggregated and formed osteoclast-like cells in chemically defined osteoclastogenesis medium with 20 ng/mL of macrophage colony-stimulating factor (M-CSF) and 50 ng/mL of receptor activator of nuclear factor κB ligand (RANKL). Strikingly, DPCs attenuated osteoclastogenesis when cocultured with primary splenocytes, whereas ABCs slightly but significantly promoted osteoclastogenesis. DPCs yielded ~20-fold lower RANKL expression but >2-fold higher osteoprotegerin (OPG) expression than donor-matched ABCs, yielding a RANKL/OPG ratio of 41:1 (ABCs:DPCs). Vitamin D3 significantly promoted RANKL expression in ABCs and OPG in DPCs. In vivo, rat maxillary incisors were atraumatically extracted (without any tooth fractures), followed by retrograde pulpectomy to remove DPCs and immediate replantation into the extraction sockets to allow repopulation of the surgically treated root canal with periodontal and alveolar bone-derived cells. After 8 wk, multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resoprtion alternating with areas of osteodentin formation in root dentin surface in the observed 8 wk. These findings suggest that DPCs of the mesenchymal compartment have an innate ability to attenuate osteoclastogenesis and that this innate ability may be responsible for the absence of dentin resorption in homeostasis. Mesenchymal attenuation of dentin resorption may have implications in internal resorption in the root canal, pulp/dentin regeneration, and root resorption in orthodontic tooth movement.