Etiological Mechanisms and Genetic/Biological Modulation Related to PTH1R in Primary Failure of Tooth Eruption.

Primary failure of eruption (PFE) is a rare disorder that is characterized by the inability of a molar tooth/teeth to erupt to the occlusal plane or to normally react to orthodontic force. This condition is related to hereditary factors and has been extensively researched over many years. However, the etiological mechanisms of pathogenesis are still not fully understood. Evidence from studies on PFE cases has shown that PFE patients may carry parathyroid hormone 1 receptor (PTH1R) gene mutations, and genetic detection can be used to diagnose PFE at an early stage. PTH1R variants can lead to altered protein structure, impaired protein function, and abnormal biological activities of the cells, which may ultimately impact the behavior of teeth, as observed in PFE. Dental follicle cells play a critical role in tooth eruption and root development and are regulated by parathyroid hormone-related peptide (PTHrP)-PTH1R signaling in their differentiation and other activities. PTHrP-PTH1R signaling also regulates the activity of osteoblasts, osteoclasts and odontoclasts during tooth development and eruption. When interference occurs in the PTHrP-PTH1R signaling pathway, the normal function of dental follicles and bone remodeling are impaired. This review provides an overview of PTH1R variants and their correlation with PFE, and highlights that a disruption of PTHrP-PTH1R signaling impairs the normal process of tooth development and eruption, thus providing insight into the underlying mechanisms related to PTH1R and its role in driving PFE.

Experimental study of the synergistic effect and network regulation mechanisms of an applied combination of BMP-2, VEGF, and TGF-ß1 on osteogenic differentiation.

The study aimed to explore the osteogenic effect induced by the combined use of bone morphogenetic protein-2 (BMP-2), vascular endothelial growth factor (VEGF), and transforming growth factor-ß1 (TGF-ß1), attain the best combination for osteogenic quality and efficiency, and explore the network regulation mechanisms of induced osteogenesis. MC3T3-E1 cells were cultured in vitro, and BMP-2, VEGF, and TGF ß1 were added to osteogenic induction mediums in different combinations to conduct experiments. At 7 and 14 days, the alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining of the applied BMP-2 and VEGF combination were deeper and the quantitative analysis were higher than those of the other groups. After optimizing the time-effect relationship of the combined application, with BMP-2, VEGF, and TGF-ß1 adding in the early stage and BMP-2 and VEGF adding in the late, the ALP and ARS staining of these groups were deeper and the quantitative analyses were meaningfully higher than the BMP-2 and VEGF combination group at 7 and 14 days. The expression of the RUNX2 gene and the Smad1 signaling pathway in the optimized combination group was also significantly higher. The results demonstrate that the combination of BMP-2, VEGF, and TGF-ß1 applied according to the time-effect relationship can significantly promote osteogenic differentiation mainly through the classical BMP-receptor-Smad signal pathway.

Preventive Efficacy of Antibiotics after Impacted Mandibular Third Molar Surgery.

OBJECTIVE: To explore the preventive efficacy of antibiotics following surgical removal of the impacted mandibular third molars and screen the potential risk factors. STUDY DESIGN: A cohort trial. Place and Duration of the Study: Department of Oral and Maxillofacial Surgery, Zhejiang University School of Medicine, Stomatology Hospital, Hangzhou, China, from August 2021 to 2022. METHODOLOGY: Cases with impacted mandibular third molar were divided into two groups based on antibiotics use. The primary outcome variable post-operative infection, secondary clinical parameter analgesics intake, and other variables (the operative time, the history of pericoronitis, and wound closure) were documented. RESULTS: The post-operative infections occurred in 3.64% (n = 12) of the 330 cases (n = 330); 3.01% in the antibiotic group (n = 166) and 4.27% in the control group (n = 164, OR = 1.44, 95% CI: 0.49 to 4.06; p = 0.54). Concerning secondary outcome measures, the analgesics that the antibiotic group took was 5.40, and the control group took was 5.95 (95% CI = -0.21 to 1.30; p = 0.16). For those with post-operative infections, the average operative time was 22.83 minutes, whereas for those without post-operative infections it was 14.87 minutes (95% CI = -0.26 to 15.67; p = 0.04). When the operative time was greater than or equal to 15 minutes, it was related to more analgesics use (95% CI: -0.43 to 1.93; p <0.05), also was the history of pericoronitis (95% CI = 0.04 to 1.54; p = 0.04). CONCLUSION: Antibiotics are unnecessary for preventing post-operative infections or minimising analgesic requirements following extraction of the impacted mandibular third molars; operative time and pericoronitis showed a suppressive influence on post-operative recovery. KEY WORDS: Impacted molars, Antibiotics, Analgesics, Operative time, Pericoronitis.

[The role of semaphorin 4D in the mechanism of bisphosphonate-related osteonecrosis of the jaw in rats].

PURPOSE: To study the expression level of semaphorin 4D (Sema4D) in bisphosphonate-related osteonecrosis of the jaw (BRONJ) and to explore its possible role in the occurrence of BRONJ. METHODS: BRONJ-like rat model was established by intraperitoneal injection of zoledronic acid assisted with tooth extraction. The maxillary specimens were extracted for imaging and histological examination, and bone marrow mononuclear cells(BMMs) and bone marrow mesenchymal stem cells(BMSCs) of each group were obtained in vitro for co-culture. Trap staining and counting were performed on monocytes after osteoclast induction. RAW264.7 cells were induced by osteoclast orientation under bisphosphonates(BPs) environment, and Sema4D expression was detected. Similarly, MC3T3-E1 cells and BMSCs were induced to osteogenic orientation in vitro, and the expression level of osteogenic and osteoclastic related genes ALP, Runx2, and RANKL was detected under the intervention of BPs, Sema4D and Sema4D antibody. Statistical analysis of the data was performed using GraphPad Prism 8.0 software. RESULTS: BRONJ-like rat model was successfully constructed. Two weeks after tooth extraction, the healing of the tooth extraction wound in the experimental group was significantly limited, and the tooth extraction wound was exposed. H-E staining results showed that regeneration of new bone in the extraction socket of the experimental group was significantly restricted, dead bone was formed, and the healing of the soft tissue was limited. The results of trap staining showed that the number of osteoclasts in the experimental group was significantly less than that in the control group. Micro-CT results showed that bone mineral density and bone volume fraction in the extraction socket of the experimental group were significantly lower than those of the control group. Immunohistochemical results showed that compared with the control group, the expression level of Sema4D in the experimental group was significantly increased. In vitro studies showed that compared with the control group, the osteoclast induction of BMMs in the experimental group was significantly lower than that in the control group. BMSCs in the experimental group significantly reduced the induction of osteoclasts. Osteoclastic induction experiments revealed that bisphosphonates could effectively inhibit the formation of osteoclasts, and the expression of Sema4D was significantly reduced. Osteogenic induction experiment found that Sema4D significantly reduced the expression of Runx2 and RANKL genes in osteoblasts, while the expression of ALP gene decreased and the expression of RANKL up-regulated after adding Sema4D antibody. CONCLUSIONS: BPs can interfere with normal bone healing time by up-regulating the expression of Sema4D in tissues, leading to coupling disorder between osteoclasts and osteoblasts with inhibition of the maturation of osteoclasts, thereby inhibiting the growth of osteoblasts. Differentiation and expression of related osteogenic factors mediate the development of BRONJ.

Adipose-Derived Stem Cells Promote Bone Coupling in Bisphosphonate-Related Osteonecrosis of the Jaw by TGF-ß1.

This study aimed to investigate molecularly targeted therapy to revive bone remodeling and prevent BRONJ by local adipose-derived stem cells (ADSCs) transplantation. Clinical samples of BRONJ and healthy jawbones were used to examine the bone coupling-related cells and TGF-ß1 expression. Bone coupling-related cells and TGF-ß1 expression were also assessed in BRONJ-like animal model to confirm the results in clinical samples. ADSCs were locally administered in vivo and the therapeutic effects were evaluated by gross observation, radiological imaging, and histological examination. Furthermore, ADSCs-conditioned medium (ADSCs-CM) and neutralizing antibody were applied to assess the effects of ADSCs-derived TGF-ß1 on restoring bone coupling in vivo. Osteoclast formation and resorption assays were performed to evaluate the effects of ADSCs-derived TGF-ß1 on ZA-treated pre-osteoclasts. Cell migration was performed to assess the effects of ADSCs-derived TGF-ß1 on patients' bone marrow stem cells (BMSCs). The number of osteoclasts, Runx2-positive bone-lining cells (BLCs) and TGF-ß1 expression were decreased in BRONJ and animal model jaw bone samples. These reductions were significantly rescued and necrotic jawbone healing was effectively promoted by local ADSCs administration in BRONJ-like animal models. Mechanistically, ADSCs-CM mainly contributed to promoting bone coupling, while TGF-ß1 neutralizing antibody in the conditioned medium inhibited these effects. Besides, osteoclastogenesis and patients' BMSCs migration were also rescued by ADSCs-derived TGF-ß1. Furthermore, bone resorption-released bone matrix TGF-ß1, together with ADSCs-derived TGF-ß1, synergistically contributed to rescuing BMSCs migration. Collectively, ADSCs promoted bone healing of BRONJ by TGF-ß1-activated osteoclastogenesis and BMSCs migration capacities.

Adipose-derived stem cells prevent the onset of bisphosphonate-related osteonecrosis of the jaw through transforming growth factor ß-1-mediated gingival wound healing.

BACKGROUND: Due to its complex pathogenesis and low clinical cure rate, bisphosphonate-related osteonecrosis of the jaw (BRONJ) poses a substantial challenge for oral and maxillofacial surgeons. Therefore, the treatment of BRONJ should focus on prevention. In clinical studies, primary wound closure can significantly reduce the incidence of BRONJ. Whether local stem cell transplantation can promote primary gingival healing in patients with a medication history and prevent BRONJ has not been reported. METHODS: In this study, animals were divided into a healthy group (non-drug treatment), a BP group, a hydroxyapatite (HA) group, and an adipose-derived stem cell (ADSC) group. All groups except the healthy group were treated with BPs and immunosuppressive drugs once per week for 8 weeks, simulating clinical use for the treatment of cancer patients with bone metastasis, to induce BRONJ-like animals. After the sixth drug treatment, the bilateral premolars were extracted in all groups. In contrast to the healthy and BP groups, the extraction sockets in the HA and ADSC groups were filled with HA or HA + ADSCs simultaneously post extraction to observe the preventive effect of ADSCs on the occurrence of BRONJ. At 2 and 8 weeks post extraction, animals from all groups were sacrificed. RESULTS: At 8 weeks post transplantation, ADSCs prevented the occurrence of BRONJ, mainly through accelerating healing of the gingival epithelium at 2 weeks post extraction. We also found that ADSCs could upregulate the expression of transforming growth factor ß1 (TGF-ß1) and fibronectin in tissue from animals with a medication history by accelerating gingival healing of the extraction socket. A rescue assay further demonstrated that TGF-ß1 and fibronectin expression decreased in TGF-ß1-deficient ADSC-treated animals, which partially abolished the preventive effect of ADSCs on the onset of BRONJ. CONCLUSION: ADSCs prevent the onset of BRONJ, mainly by upregulating the expression of TGF-ß1 and fibronectin to promote primary gingival healing, ultimately leading to bone regeneration in the tooth extraction socket. Our new findings provide a novel stem cell treatment for the prevention of BRONJ.

[Preparation and examination of BMP-2 loaded chitosan nanospheres in vitro].

PURPOSE: To prepare chitosan nanospheres for loading of BMP-2 and to evaluate its size, zeta potential, appearance, degradation and release characteristic in vitro, and then to investigate its feasibility as a carrier for sustained release of BMP-2. METHODS: The BMP-2 loaded chitosan nanospheres were prepared using ionic crosslinking method with tripolyphosphate (TPP) and chitosan. Transmission electron microscope was used to evaluate the morphological properties, and laser particle size analyzer was used to analyze particle size, Zeta potential and distribution. Lysozyme degradation experiment was performed to assess the biodegradation behavior. ELISA assay was used to determine the loading efficiency, encapsulation efficiency and in vitro drug release kinetics. The data was analyzed by SPSS 19.0 software package. RESULTS: The BMP-2 loaded chitosan nanospheres were spherical in shape, smooth on surface and uniform dispersion without aggregation. The mean diameter was 150.85 nm. The dispersion index was 0.37, and zeta potential was +35.42 mV. The average loading efficiency and encapsulation efficiency were (56.83 ± 2.26)% and (68.24 ± 3.83)%, respectively. Release experiment in vitro showed that the releasing property of BMP-2 loaded chitosan nanospheres was consistent with two-phase kinetic regulation and BMP-2 was controlled to release from the chitosan nanospheres over 30 days. CONCLUSIONS: The BMP-2 loaded chitosan nanospheres prepared by ionic crosslinking method are successfully prepared which show a good controlled release property. It provides the basis for further application in bone tissue engineering.