Can concentrated growth factor prevent postoperative complications of impacted third molar surgery? A split-mouth randomized double-blind trial.

OBJECTIVES: The purpose of the present study was to evaluate the effect of concentrated growth factor (CGF) on prevention of postoperative complications in the impacted third molar extraction. MATERIALS AND METHODS: A total of 25 healthy patients with symmetrical bilaterally impacted third molars (50 extraction sites) were enrolled in this split-mouth, randomized, double-blind clinical trial. Third molar extractions were performed in both sites of the mandible at the same appointment. Randomization was performed using a coin toss to choose the test and control sites. CGF was placed in the extraction socket and the socket was sutured (test group), while the contralateral socket was only sutured (control group). Each patient acted as their own control. The primary outcome were pain assessed by visual analog scale (VAS) and facial swelling on the1st, 3rd and 7th postoperative days. The secondary outcomes were bone healing in extraction sockets through alveolar bone height (ABH) and alveolar bone density (ABD) evaluated by cone beam computed tomography (CBCT) immediately after extraction and in the 3rd and 6th months. RESULTS: Twenty-five patients (12 female, 13 male; mean age 29.17) with bilateral impacted third molars participated in the study. A statistically significant reduction in pain was determined on the 3rd and 7th postoperative days in the CGF sites compared to the control sites while no statistically significant difference was found between the groups on the 1st postoperative day (3rd day, p = 0.009; 7th day, p = 0.039). There were no statistically significant differences in facial swelling and bone healing between the test and control groups at different time intervals, although the data obtained were slightly favoring the CGF group (p > 0.05). There were no serious adverse effects such as infection, alveolitis, paraesthesia, fracture through the follow-up period in all of the cases. CONCLUSION: The study has demonstrated the effect of CGF on relieving the severity of pain after the third molar extraction. CLINICAL RELEVANCE: Placement of CGF in the extraction socket could relieve postoperative pain and reduce patient discomfort after the third molar extraction. CGF is recommended during the third molar extraction due to its good biological effects, low cost and simple preparation procedures. TRIAL REGISTRATION NUMBER: ChiCTR2300077819.

Knockout of NRAGE promotes autophagy-related gene expression and the periodontitis process in mice.

BACKGROUND AND OBJECTIVE: Neurotrophin receptor-interacting MAGE homologue (NRAGE) plays a crucial role in the regulation of bone metabolism. The present study investigated the regulation role of NRAGE on autophagy activation and periodontitis process during experimental periodontitis. MATERIALS AND METHODS: Six-week-old wild-type (WT) and NRAGE-/- mice were randomly divided into three time points in the periodontitis groups (0, 2, and 4 weeks). Histopathological changes were determined using the tooth mobility, hematoxylin and eosin (H&E) staining, and micro-computed tomography (micro-CT). Osteoclasts activation and number were investigated using tartrate-resistant acid phosphatase (TRAP) staining, immunohistochemistry, and real-time quantitative PCR (RT-PCR). The level of autophagy-related gene expression was measured using immunohistochemistry, immunofluorescence, and RT-PCR. RESULTS: H&E staining and Micro-CT showed that the destruction of the alveolar bone was considerably more severe in the NRAGE-/- group than the WT group after ligation. Tooth mobility in the NRAGE-/- group was obviously higher than that in the WT group. The activation and number of osteoclasts and the level of autophagy-related gene expression in NRAGE-/- group were significantly higher than that in WT group. CONCLUSIONS: The present study showed that knockout of NRAGE induced autophagy-related gene expression and accelerated the process of periodontitis disease via increasing the activity and differentiation of osteoclast.

Knockdown of NRAGE induces odontogenic differentiation by activating NF-κB signaling in mouse odontoblast-like cells.

PURPOSE: Neurotrophin receptor-interacting MAGE homologue (Nrage) plays an important role in bone development and the metabolism of normal skeletal structures. Our previous study showed that Nrage inhibited the odontogenic differentiation of mouse dental pulp cells. However, the potential roles and mechanism of Nrage in regulating odontogenic differentiation are unknown. The aim of this study was to investigate the molecular mechanism of Nrage in odontogenic differentiation of mouse odontoblast-like cells. MATERIALS AND METHODS: Endogenous expression of Nrage was stably downregulated by lentivirus-mediated shRNA. Mineralized nodules formation was detected by alizarin red S staining. Dmp-1, Dspp, and ALP mRNA and protein levels were detected by qRT-PCR and western blotting, respectively. In addition, ALPase activity was detected. Confocal microscopy and co-immunoprecipitation (co-IP) were used to analyze the interactions between NRAGE and NF-κB signaling molecules. An IKK inhibitor was also used in the study. RESULTS: NRAGE expression in odontoblasts was downregulated during mouse first maxillary molar development. Moreover, NRAGE expression was downregulated during odontogenic differentiation of odontoblast-like cells. NRAGE knockdown significantly upregulated DMP1 and DSP expression, increased ALPase activity, and promoted mineralized nodule formation. In addition, NRAGE knockdown increased the translocation of NF-κB1 to the nucleus and phosphorylation levels of p65. Co-IP results showed that NRAGE bound to IKKß. Most importantly, the promoting effect of Nrage knockdown on odontoblastic differentiation was reduced after treatment with an IKK inhibitor. CONCLUSIONS: Our data confirmed that NRAGE is an important regulator of odontogenic differentiation of odontoblasts by inhibiting the NF-κB signaling pathway through binding to IKKß. ABBREVIATIONS: Nrage: neurotrophin receptor-interacting MAGE homologue; DSP: dentin sialophospho protein; DMP-1: dentin matrix protein-1; BMP: bone morphogenetic protein; Wnt: wingless; NF-κB: nuclear factor of activated B cells; DAPI: 4',6-diamidino-2-phenylindole; KO: knockout; DPCs: dental pulp cells; AA: ascorbic acid; ß-Gly: ß-glycerophosphate; Dex: dexamethasone; co-IP: co-immunoprecipitation; IκB: inhibitor of NF-κB; IKK: IκB kinase.

Chemical Stability and Antimicrobial Activity of Plasma-Sprayed Cerium Oxide-Incorporated Calcium Silicate Coating in Dental Implants.

PURPOSE: The aim of this study is to investigate the biological activity and antibacterial property of cerium oxide-incorporated calcium silicate coatings (CeO2-CS) in dental implants. MATERIALS AND METHODS: In this study, MC3T3-E1 cells cultured on the plastic, Ti-6Al-4V, and the cerium oxide-incorporated calcium silicate coatings (CeO2-CS) coating served as the blank, control, and CeO2-CS groups, respectively. A cell counting kit-8 (CCK-8) and flow cytometry were used to evaluate the biocompatibility. The osteoblastic differentiation of the MC3T3-E1 cells was also analyzed by quantitative real-time polymerase chain reaction analysis. The CCK-8 and counts of colony-forming units (CFUs) were used to detect the antibacterial activity of the coating on Enterococcus faecalis. The study showed that the cerium oxide-incorporated calcium silicate coating (CeO2-CS) has better biocompatibility. Meanwhile, the ALP, OCN, and BSP mRNA expression levels in the CeO2-CS group were significantly upregulated (P < 0.05). The number of viable bacteria and the CFU results were significantly reduced in the CeO2-CS group (P < 0.05). CONCLUSION: The cerium oxide-incorporated calcium silicate coatings (CeO2-CS) may promote the osteoblastic differentiation of osteoblasts. Meanwhile, the cerium oxide-incorporated calcium silicate coating (CeO2-CS) showed strong antimicrobial activity on E. faecalis, with good biocompatibility.

[Research on the mechanical differences of machinable lithium disilicate all-ceramic crowns].

Due to the superior pigment and high flexural strength, machinable lithium disilicate ceramics can be used as a monolithic crown or veneering porcelains on the zirconia core to form the all-ceramic crowns by sintering or bonding procedures. This paper reports the research on the differences in stress distributions amongst these three types of all-ceramic crowns under typical loading conditions. Three-dimensional numerical models of the restored crown based on the first mandibular molar were developed. The vertical concentrated load and 8-point uniformly distributed load were applied, respectively. The maximum stress and stress distribution were resulted from finite element evaluation. It was found that the maximum tensile stress in 3 types of restored crowns subjected to the concentrate load was less than the flexural strength of IPS e.max. The stress distributions in the sintered and bonded double layered crowns were basically identical, and different from the monolithic crown. The stress magnitude in veneer porcelain of the bonded crown was greater than that in the sintered crown. The use of IPS e.max computer aided design monolithic crown as molar restorations should be careful to avoid high stress as the cyclic stress is a concern of fatigue which may influence the longevity of the restored crown. The bonded double layer crowns bear greater risks of veneer chipping compared with the sintered crowns. The conclusions of this study provide helpful guidelines in clinical applications for preparation of computer aided design/computer aided manufacture lithium disilicate all-ceramic restorations.

Effect of storage temperature on the viability of human periodontal ligament fibroblasts.

BACKGROUND: The viability of periodontal ligament fibroblasts (PDLF) can affect the long-term prognosis of replanted avulsed teeth. When immediate replantation of an avulsed tooth is not possible, the cells should be incubated in a physiological storage medium instantly to maintain their biological activity. The ability of different storage media to preserve PDLF viability has been previously evaluated. However, few studies have showed the effect of temperature on the viability of PDLF cultured with various storage media in vitro. MATERIAL AND METHODS: This study was designed to measure PDLF activity by CCK-8 assay to compare the effectiveness at 4, 22 (room temperature), and 37°C under various storage media. RESULTS: Statistical analysis demonstrated that tap water, saline, and saliva decreased cell viability as the storage temperature increased. But the temperature played only a minor role on cell viability when cells were incubated in Hank's balanced salt solution (HBSS), Dubelco's modified Eagle's medium (DMEM), or milk. CONCLUSIONS: Within the parameters of this study, it seems that room temperature is adequate for storing the avulsed teeth in HBSS, DMEM, or milk in the extra-alveolar period.

Porphyromonas gingivalis as a promotor in the development of the alcoholic liver disease via ferroptosis.

Alcoholic liver disease (ALD) is a liver disease caused by heavy drinking. Porphyromonas gingivalis (P.g), a major cause of periodontitis, whose antibodies are elevated in severe ALD patients in the plasma. The purpose of this study is to further study the role and the molecular mechanism of P.g in the progress of ALD. In this study, saliva of patients with ALD was collected. Then, an animal model of ALD with oral P.g administration was established, pathology of liver and spleen, intestinal microorganisms and metabolites were analyzed. The molecular mechanism of P.g on ALD was analyzed in vitro. ALD and intestinal microflora and metabolite changes were observed more serious in the alcohol and P.g groups than the alcohol group. Moreover, ferroptosis was aggravated by P.g in the liver. Meanwhile, P.g promoted ferroptosis accomplication with alcohol in vitro, which can be reversed by ferroptosis inhibitors. In conclusion, P.g aggravates ALD through exacerbation gut microbial metabolic disorder in mice with alcohol, which maybe depend on ferroptosis activation in hepatocytes. The study provides a new strategy for prevention and treatment of ALD by improving the oral micro-environment.

[Effectiveness assessment of 3-D cone beam CT used in human bite marks identification].

The present study was aimed to use the 3-D cone beam CT (CBCT) as a new method in human bite marks identification which was carried out in experimental pigskin to assess its effectiveness in our laboratory. Bite marks were digital photographed according to American Board of Forensic Odontology (ABFO) guidelines. In this study, the data of the suspect's dental casts were collected by scanning in two ways: one was after plate scanning, in which the comparison overlays were generated by Adobe Photoshop 8.0 software; the other was by CBCT, which generated comparison overlays automatically. The bite marks were blind identified with the two kinds of data of the suspect's dental casts respectively. ROC curve was used to analyze the sensitivity, specificity, and 95% confidence interval. The results showed that CBCT method got a larger area under the ROC curve: 0.784 (SE = 0.074, 95% CI = 0.639-0.929), and got a very high specificity (specificity 98.7%, 95% CI = 94.5%-99.8%). Thus, this study illustrates that the CBCT used in bite mark identification is an effective and accurate tool and has stronger ability to exclude suspects compared with the conventional method, but the comparison process needs further study to enhance its effectiveness in bite mark identification.

Porphyromonas gingivalis induced UCHL3 to promote colon cancer progression.

Porphyromonas gingivalis (P. gingivalis), a Gram-negative oral anaerobe, was demonstrated to facilitate colonization and progression in colonic tumor, while the underlying mechanism still remains to be clarified. Here, we identified the proteome profile changed by P. gingivalis infection in HCT116 cells through label-free quantitative proteomics, and found that deubiquitinase UCHL3 was a key protein that response for P. gingivalis infection. By CCK8, colony formation, wound healing assays, and in vivo subcutaneous tumor mouse moudle, we proved that P. gingivalis could promote the proliferation and migration of colon cancer, while the process was inhibited by UCHL3 knock down. Through IP-MS, we identified GNG12 as the UCHL3 interacting protein. The protein level of GNG12 was significantly reduced when knock out UCHL3. Thus we propose that GNG12 is a substrate protein of UCHL3. Furthermore, we demonstrated that overexpression of GNG12 could restore the tumor inhibition effect caused by UCHL3 knock down, and UCHL3-GNG12 axis promote colon cancer progression via the NF-κB signal pathway. Collectively, this study unveiled that P. gingivalis infection up-regulated UCHL3 and stabilized its substrate protein GNG12 to activate the NF-κB signal pathway to promote colon cancer progression. Our study indicate that UCHL3 is a potential biomarker and therapeutic target for colon cancer which infected with P. gingivalis.

Periodontitis exacerbates atherosclerosis through Fusobacterium nucleatum-promoted hepatic glycolysis and lipogenesis.

AIMS: Positive associations between periodontitis (PD) and atherosclerosis have been established, but the causality and mechanisms are not clear. We aimed to explore the causal roles of PD in atherosclerosis and dissect the underlying mechanisms. METHODS AND RESULTS: A mouse model of PD was established by ligation of molars in combination with application of subgingival plaques collected from PD patients and then combined with atherosclerosis model induced by treating atheroprone mice with a high-cholesterol diet (HCD). PD significantly aggravated atherosclerosis in HCD-fed atheroprone mice, including increased en face plaque areas in whole aortas and lesion size at aortic roots. PD also increased circulating levels of triglycerides and cholesterol, hepatic levels of cholesterol, and hepatic expression of rate-limiting enzymes for lipogenesis. Using 16S ribosomal RNA (rRNA) gene sequencing, Fusobacterium nucleatum was identified as the most enriched PD-associated pathobiont that is present in both the oral cavity and livers. Co-culture experiments demonstrated that F. nucleatum directly stimulated lipid biosynthesis in primary mouse hepatocytes. Moreover, oral inoculation of F. nucleatum markedly elevated plasma levels of triglycerides and cholesterol and promoted atherogenesis in HCD-fed ApoE-/- mice. Results of RNA-seq and Seahorse assay indicated that F. nucleatum activated glycolysis, inhibition of which by 2-deoxyglucose in turn suppressed F. nucleatum-induced lipogenesis in hepatocytes. Finally, interrogation of the molecular mechanisms revealed that F. nucleatum-induced glycolysis and lipogenesis by activating PI3K/Akt/mTOR signalling pathway in hepatocytes. CONCLUSIONS: PD exacerbates atherosclerosis and impairs lipid metabolism in mice, which may be mediated by F. nucleatum-promoted glycolysis and lipogenesis through PI3K/Akt/mTOR signalling in hepatocytes. Treatment of PD and specific targeting of F. nucleatum are promising strategies to improve therapeutic effectiveness of hyperlipidaemia and atherosclerosis.

Ultrafine particles exposure is associated with specific operative procedures in a multi-chair dental clinic.

Air quality in dental clinics is critical, especially in light of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic, given that dental professionals and patients are at risk of regular exposure to aerosols and bioaerosols in dental clinics. High levels of ultrafine particles (UFP) may be produced by dental procedures. This study aimed to quantify ultrafine particles (UFP) concentrations in a real multi-chair dental clinic and compare the levels of UFP produced by different dental procedures. The efficiency of a high-volume evacuator (HVE) in reducing the UFP concentrations during dental procedures was also assessed. UFP concentrations were measured both inside and outside of a dental clinic in Shanghai, China during a 12-day period from July to September 2020. Dental activities were recorded during working hours. The mean (±standard deviation) concentrations of indoor and outdoor UFP during the sampling period were 8,209 (±4,407) counts/cm3 and 15,984 (±7,977) counts/cm3, respectively. The indoor UFP concentration was much higher during working hours (10,057 ± 5,725 counts/cm3) than during non-working hours (7,163 ± 2,972 counts/cm3). The UFP concentrations increased significantly during laser periodontal treatment, root canal filling, tooth drilling, and grinding, and were slightly elevated during ultrasonic scaling or tooth extraction by piezo-surgery. The highest UFP concentration (241,136 counts/cm3) was observed during laser periodontal treatment, followed by root canal filling (75,034 counts/cm3), which showed the second highest level. The use of an HVE resulted in lower number concentration of UFP when drilling and grinding teeth with high-speed handpieces, but did not significantly reduce UFP measured during laser periodontal therapy. we found that many dental procedures can generate high concentration of UFP in dental clinics, which may have a great health impact on the dental workers. The use of an HVE may help reduce the exposure to UFP during the use of high-speed handpieces.

In vitro anti­bacterial activity of diosgenin on Porphyromonas gingivalis and Prevotella intermedia.

Diosgenin (Dios), a natural steroidal sapogenin, is a bioactive compound extracted from dietary fenugreek seeds. It has a wide range of applications, exhibiting anti­oxidant, anti­inflammatory and anti­cancer activities. However, whether the extracts have beneficial effects on periodontal pathogens has so far remained elusive. The aim of the present study was to investigate the anti­bacterial effects of Dios on Porphyromonas gingivalis (P. gingivalis) and Prevotella intermedia (P. intermedia) in vitro. The anti­microbial effect of Dios on P. gingivalis and P. intermedia was assessed by a direct contact test (DCT) and the Cell Counting Kit (CCK)­8 assay at 60, 90 and 120 min. In addition, counting of colony­forming units (CFU) and live/dead cell staining were used to evaluate the anti­bacterial effects. The results of the DCT and CCK­8 assays indicated that Dios had beneficial dose­dependent inhibitory effects on P. gingivalis and P. intermedia. The CFU counting results also indicated that Dios had dose­dependent anti­bacterial effects on P. gingivalis and P. intermedia. Of note, Dios had significant anti­bacterial effects on the biofilms of P. gingivalis and P. intermedia in vitro as visualized by the live/dead cell staining method. In conclusion, the present results demonstrated that Dios had a marked anti­bacterial activity against P. gingivalis and P. intermedia in vitro, both in suspension and on biofilms. The present study highlighted the potential applications of Dios as a novel natural agent to prevent and treat periodontitis through its anti­bacterial effects.

In Vitro Study of Bond Strength Between Abutments with Different Degrees of Convergence and Crowns by Pre-Bonding Method.

PURPOSE: To investigate the optimal degree of convergence of the abutment with which the bond strength achieved by the pre-bonding method is comparable with that in direct bonding with a conventional degree of convergence. MATERIALS AND METHODS: Abutments with 5.5-mm diameter, 5-mm height, 0.5-mm shoulder width, and three kinds of degrees of convergence (2, 4, and 6 degrees) were first designed by digital modeling. Their corresponding inner crowns were also modeled, and a gap of 40 µm was kept between the abutment and the inner crown. Thirty abutments and 30 inner crowns were then lathed out from a titanium plate (10 sets per degree of convergence). Six groups were defined in this study, according to the different degrees of convergence and bonding methods (direct bonding, pre-bonding) (n = 10 sets). The samples handled with direct bonding would be cleaned for reuse in tests with pre-bonding. Temporary cement was used as an adhesive, and the bond strength was tested in each set of samples. The comparison among the results was performed by the Kruskal-Wallis test. RESULTS: The mean values of bond strength with direct bonding methods were 349.39 ± 65.75 N, 316.49 ± 54.22 N, and 277.49 ± 56.96 N, and with pre-bonding methods were 279.35 ± 48.58 N, 227.97 ± 26.72 N, and 154.6 ± 23.03 N, respectively (2, 4, and 6 degrees). No statistical difference was found among the values in direct bonding groups and, in pre-bonding groups, only the comparison between 2 and 6 degrees of convergence showed statistical significance (P = .000). Between different bonding methods, statistical differences were shown in abutments with 4 and 6 degrees of convergence (P = .006, P = .000), respectively. The bond strength with pre-bonding methods and 2 degrees of convergence showed no significant difference from that with direct bonding and 6 degrees of convergence. CONCLUSION: The bond strength was inversely proportional to the degree of convergence, and the bond strength of pre-bonding was lower than that of direct bonding with the same degree of convergence. When using the pre-bonding method, the bond strength between the abutment and inner crown with 2 degrees of convergence could be comparable with using the direct bonding method and abutments with conventional degrees of convergence.

Expression of autophagy­associated proteins in rat dental irreversible pulpitis.

Autophagy serves an important role in numerous diseases, as well as in infection and inflammation. Irreversible pulpitis (IP) is one of the most common inflammatory endodontic diseases, and autophagy has been reported to regulate IP in vitro. However, the level of autophagy in the IP pathogenic process in vivo remains unknown. The aim of the current study was, thus, to investigate the levels of autophagy­associated proteins in rats with IP in vivo. A rat dental IP model was successfully constructed, and five different time points (0, 1, 3, 5 and 7 days) were investigated. The levels of the autophagy­related 5 (ATG5), ATG7, light chain 3 (LC3) and Beclin­1 proteins exhibited a time­dependent increase in rats with IP, whereas the levels of mammalian target of rapamycin and p62/sequestosome 1 were decreased. In addition, the levels of ATG proteins were specifically increased in odontoblasts and microvascular endothelial cells in pulpitis tissue. Based on these findings, autophagy may serve an important role in IP, and the present study data provide a new insight into the IP pathogenesis and treatment.

The effect of adhesive failure and defects on the stress distribution in all-ceramic crowns.

OBJECTIVES: To explore the effect of adhesive failure and defects between the crown and cement on the stress distribution within all-ceramic crowns and the corresponding risk of failure. METHODS: An IPS e.max crown of lithium disilicate produced by CAD/CAM for a first mandibular molar was modeled using finite element analysis based on X-ray micro-CT scanned images. Predefined debonding states and interfacial defects between the crown and cement were simulated using the model. The first principal stress distribution of the crown and cement was analyzed under a vertical occlusal load of 600 N. A concept of failure risk was proposed to evaluate the crown. RESULTS: Stress concentrations in the crown were identified on the occlusal surface surrounding the region of loading, beneath the area of loading and at the margin of the interior surface. Stress concentrations in the cement were also evident at the boundary of the debonded areas. The lower surface of the crown is safe to sustain the 600 N vertical load, but the top surface of the cement would undergo cohesive failure. According to the evaluation of failure risk of the crown, the conditions of highest risk corresponded to the conditions with highest percentage of cement damage. The risk of failure is not only associated with debonding between the crown and cement, but also associated with its distribution. CONCLUSIONS: Debonding related defects and cementing defects are more deleterious to the interfacial stress than debonding itself. The axial wall plays a critical role in maintaining the principal tensile stress of the crown at an acceptable level.

The effect of delta-like 1 homologue on the proliferation and odontoblastic differentiation in human dental pulp stem cells.

INTRODUCTION: This study aimed to investigate the functions of delta-like homologue 1 (DLK1) in the proliferation and differentiation of human dental pulp stem cells (hDPSCs). METHODS: Immunohistochemical analysis was used to determine the expression of alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP), DLK1, NOTCH1 and p-ERK1/2 in the mouse first maxillary molar. Recombinant lentivirus was constructed to overexpress DLK1 stably in hDPSCs. The cell viability and proliferation of hDPSCs were examined by CCK8 and EdU incorporation assay respectively. The odontoblastic differentiation of hDPSCs was determined by detection of ALPase activity assay, ALP and alizarin red staining and the expression of mineralization-related genes including ALP, DSPP and dental matrix protein. The mRNA and protein levels of DLK1 and p-ERK1/2 protein expression were detected. ERK inhibitor was used to test the differentiation effect of DLK1 on hDPSCs. RESULTS: Delta-like homologue 1 was highly expressed on the odontoblasts and dental pulp cells on the first maxillary molar; the expression of p-ERK1/2 is similar with the DLK1 in the same process. The expression level of DLK1 increased significantly after the odontoblastic induction of hDPSCs. DLK1 overexpression increased the proliferation ability of hDPSCs and inhibited odontoblastic differentiation of hDPSCs. The protein level of p-ERK1/2 significantly increased in hDPSCs/dlk1-oe group. ERK signalling pathway inhibitor reversed the odontoblastic differentiation effects of DLK1 on hDPSCs. CONCLUSIONS: The proliferation of hDPSCs was promoted after DLK1 overexpression. DLK1 inhibited the odontoblastic differentiation of hDPSCs, which maybe through ERK signalling pathway.

DNA methylation is critical for tooth agenesis: implications for sporadic non-syndromic anodontia and hypodontia.

Hypodontia is caused by interactions among genetic, epigenetic, and environmental factors during tooth development, but the actual mechanism is unknown. DNA methylation now appears to play a significant role in abnormal developments, flawed phenotypes, and acquired diseases. Methylated DNA immunoprecipitation (MeDIP) has been developed as a new method of scanning large-scale DNA-methylation profiles within particular regions or in the entire genome. Here, we performed a genome-wide scan of paired DNA samples obtained from 4 patients lacking two mandibular incisors and 4 healthy controls with normal dentition. We scanned another female with non-syndromic anodontia and her younger brother with the same gene mutations of the PAX9,MSX1,AXIN2 and EDA, but without developmental abnormalities in the dentition. Results showed significant differences in the methylation level of the whole genome between the hypodontia and the normal groups. Nine genes were spotted, some of which have not been associated with dental development; these genes were related mainly to the development of cartilage, bone, teeth, and neural transduction, which implied a potential gene cascade network in hypodontia at the methylation level. This pilot study reveals the critical role of DNA methylation in hypodontia and might provide insights into developmental biology and the pathobiology of acquired diseases.

The correlations between health-related quality of life changes and pain and anxiety in orthodontic patients in the initial stage of treatment.

This study aimed to assess generic health-related quality of life (HRQoL), pain intensity, and anxiety levels and the relationship between the three aspects in healthy young Chinese orthodontic patients in the early stage of orthodontic treatment. We enrolled 252 eligible participants (10-29 years old) to complete validated Chinese versions of questionnaires, including the State-Trait Anxiety Inventory (S-AI), the visual analogue scale (VAS), and the Short-Form 36-Item Health Survey (SF-36) at baseline and on days 1, 2, 3, 7, 14, and 30 after initial archwire placement (SF-36 only at baseline and day 30). The response rate was 96% (243 of 252). SF-36 had moderate reliability (Cronbach's alpha coefficient exceeding 0.7, good fit on day 30). Statistical significant changes were observed in physical function (P < 0.01), body pain (P = 0.01), and general health (P < 0.01) domains. Spearman correlation coefficients for SF-36 with S-AI were -0.131~-0.515 (P < 0.05); SF-36 with VAS were -0.141~-0.273 (P < 0.05), indicating significant but moderate negative correlations between HRQoL and pain/anxiety. Overall, the application of SF-36 in assessing HRQoL is reluctantly suitable for young Chinese orthodontic patients in the early stage of orthodontic treatment. Early treatment-related pain and anxiety are important factors in HRQoL.

A novel model of bisphosphonate-related osteonecrosis of the jaw in rats.

OBJECTIVE: To establish a rat model of bisphosphonate-related osteonecrosis of the jaw (BRONJ) that realistically mimics major clinical manifestations of the disease. METHODS: Female Sprague Dawley rats received intravenous zoledronate 80 µg/kg once a week via the tail vein. Three weeks after intravenous injection, maxillary first molars were extracted under general anesthesia. Then 1, 4 and 12 weeks after tooth extraction, the rats were euthanized, and the intact maxillas were harvested en bloc. Macroscopic analysis, histological analysis and cytokine analysis were performed. Untreated rats with tooth extraction were used as controls. RESULTS: 12 weeks after extraction, rats treated with zoledronate developed BRONJ-like disease, including characteristic features of impaired soft tissue healing, exposed necrotic bone or sequestra, increased inflammatory infiltrates, while the controls showed normal bone healing. 4 weeks after extraction, rats treated with zoledronate exhibited the decreased receptor activator of nuclear factor kappa-B ligand (RANKL) values, the increased osteoprotegerin (OPG) values and the remarkable decreased RANKL/OPG ratio when compared with the controls. CONCLUSION: The rats treated with zoledronate can be considered a novel, reliable and reproducible animal model to better understand the pathophysiology and pathogenesis of BRONJ and to develop a therapeutic approach.

The Effect of NRAGE on cell cycle and apoptosis of human dental pulp cells and MDPC-23.

OBJECTIVES: Neurotrophin receptor-mediated melanoma antigen-encoding gene homology (NRAGE) is an important regulator of proliferation, cell cycle arrest and apoptosis. Our previous study showed that NRAGE is an important regulator of proliferation and odontogenic differentiation of mouse dental pulp cells. This study aimed to investigate the effects of NRAGE on the cell cycle and apoptosis on human dental pulp cells (hDPCs) and MDPC-23. MATERIALS AND METHODS: Cells were infected by recombinant lentivirus to stably knockdown the expression of NRAGE, then the biological effects of NRAGE on the MDPC-23 was detected. The cell cycle distributions and apoptosis of hDPCs and MCPC-23 were performed by flow cytometric analysis. Simultaneously, the cell cycle and apoptosis were also detected after cells treated with IKK inhibitor. RESULTS: The mRNA and protein levels of NRAGE decreased significantly after infected by recombinant lentivirus. Knockdown of NRAGE inhibited the apoptosis in hDPCs and MCPC-23. Knockdown of NRAGE show significantly G0G1 arrest in hDPCs, while no significantly difference in MDPC-23. Meanwhile, Knockdown of NRAGE activated the NF-κB signaling pathway. After treated with IKK inhibitor, the effect of NRAGE knockdown on apoptosis was reversed in both hDPCs and MDPC-23. CONCLUSION: NRAGE is a potent regulator for cell cycle and apoptosis of hDPCs. Knockdown of NRAGE inhibited apoptosis of hDPCs and MDPC-23 through the NF-κB signaling pathway.