Biomaterials have been the focus of research and innovation in medical materials in recent years. They are natural or synthetic materials that can contact and interact with human cells, tissues and organs to obtain diagnostic, restorative or therapeutic effects. In stomatology, biomaterials have received high attention, such as applications in implant restorations, pulp regeneration, periodontal tissue regeneration and other frontier fields. Dentine hypersensitivity is manifested as short and sharp pain from stimulus to exposed dentin, which has high prevalence and seriously affects people's daily life. However, the pathogenesis is still controversial and traditional treatment is ineffective. Recently, various biomaterials have been invented to treat dentine hypersensitivity. This paper reviews the innovative development of biomaterials in the treatment of dentine hypersensitivity and highlights the ionic mechanism. It is expected that biomaterials can provide new models and ideas for exploring the pathogenesis and therapies of oral diseases.

Objective To investigate the effect of Notch1^P1641S mutation on oral squamous cell carcinoma. Methods CAL27 and HSC3 were cultured in vitro. Notch1^N1 (N1-N1), Notch1^WT (N1-WT) and Notch1^P1641S (N1-P1641S) locus mutant plasmids were constructed. Plasmids were transfected into cell lines and the transfection efficiency was examined by qPCR and Westen blot assay. The effects of Notch1 mutation on proliferation, invasion and migration of CAL27 and HSC3 cells were investigated by CCK-8 assay, plate colony formation assay, Scratch assay, EdU assay and Transwell invasion assay. Western blot was used to detect the expression of cellular pathways. The effect of mutant plasmids on oral squamous carcinoma was further verified by subcutaneous tumorigenesis assay in nude mice. Results The results of the phenotypic assay showed that the proliferation, migration and invasion ability of oral squamous carcinoma cell lines in the N1-P1641S group were enhanced after transfection with the mutant plasmid compared to the N1-N1 and N1-WT groups. The results of Westen blot experiments showed that the expression of PI3K/Akt-related indicators was upregulated in the N1-P1641S group after transfection with the mutant plasmid. Subcutaneous tumorigenesis in nude mice showed an increase in tumor size after transfection with the mutant plasmid. The expression of Ki67, a proliferation-related indicator, was enhanced. Conclusion Notch1^P1641S expression site mutation promotes proliferation of oral squamous carcinoma cells through PI3K/Akt signaling pathway.

Objective To investigate the effect and mechanism of glucose regulated protein78 (GRP78) on the proliferation and metastasis of tongue squamous cell carcinoma(TSCC) treated with cisplatin. Methods MTT assay was used to detect the proliferation of CAL27 and CAL27DR cell. RNA interference was used to knockdown GRP78 expression in CAL27DR cells and then cells were treated with DDP(0 μmol/L, 2.5 μmol/L, 5.0 μmol/L and 10.0 μmol/L)and the proliferation ability was detected by EdU. Transwell assay was used to detect the invasive potential and scratch assay was used to detect the migration potential in CAL27DR and siGRP78 cells. Immunofluorescence assay was used to detect the expression of Cortactin. Western blot assay was used to detect the protein expression of ERK, p-ERK, AKT, p-AKT, FAK, p-FAK, N-cad and E-cad in CAL27DR and siGRP78 cells. Results MTT result showed that the proliferation potential was increased obviously in CAL27DR cells compared with CAL27 cells. EdU assay result showed that the proliferation potential was decreased obviously in siGRP78 cells compared with vector (P<0.05).Transwell and scratch assay results showed that the invasive and migration potential was also decreased in siGRP78 cells compared with vector (P<0.05). Immunofluorescence assay result showed that Cortactin protein expression was decreased in siGRP78 cells compared with vector. The phosphorylation levels of ERK, AKT and FAK were significantly increased in siGRP78 cells compared with vector (P<0.05). The protein expression of N-cad was increased in siGRP78 cells compared with vector and the protein expression of N-cad has the opposite trend (P<0.05). Conclusion GRP78 up-regulates cell proliferation through ERK and AKT kinases, resulting in decreased sensitivity of cells to DDP, and mediates the occurrence of EMT and promotes cell invasion and metastasis by activating FAK kinase in tongue squamous cells.

Objective To study the effect of copper ions on the dental pulp regenerative ability of dental pulp stem cells (DPSCs) and its primary mechanism. Methods After DPSCs were stimulated with culture medium containing copper in different concentrations, CCK-8 assay was employed for evaluating the proliferation of DPSCs and toxic effects on DPSCs; Calcein-AM/PI kit was used to test the cytotoxicity of hydrogel; Western blotting and qPCR was used to detect the protein and mRNA expression of hypoxia inducible factor-1α (HIF-1α), chromobox protein homolog 7 (CBX7) and stemness-related indicators; the phenotype of angiogenesis was examined by human umbilical vein endothelial cells (HUVECs) tubes formation assay and migration assay; the copper-containing hydrogel loaded with DPSCs was prepared and injected into the subcutaneous of nude mice for two weeks, and then hematoxylin-eosin (HE) and immunohistochemistry (IHC) staining were used to observe the self-renewal and angiogenesis of DPSCs under the skin. Results The in vitro results showed that 5, 25, 50 μmol/L copper ions could promote the proliferation of DPSCs and had no significant toxic effects on DPSCs; Western blotting and qPCR results displayed the protein and mRNA levels of HIF-1α, CBX7, Sox-2, Oct-4 and Nanog in 25 μmol/L copper ions group were higher than that in the control group. Copper ions (25 μmol/L) could improve the tube formation and migration of HUVECs. The in vivo results showed that the copper-containing hydrogel loaded with DPSCs could lead to angiogenesis and increase dramatically the expression of Sox-2 in the subcutaneous of nude mice. Conclusion Copper ions can activate HIF-1α, enhance the expression of CBX7, and then upregulate Sox-2, Oct-4 and Nanog to maintain the stemness of DPSCs, meanwhile, can induce the regeneration of blood vessels, which can provide theoretical and experimental foundation for the regeneration of dental pulp.

Objective To investigate the effect of tantalum-coated surface on the proliferation and ossification of human periodontal ligament stem cells(hPDLSCs). Methods The hPDLSCs were separated and cultured, with the cell identified. After polishing and cleaning of pure titanium specimens, the tantalum coating was prepared by plasma spraying technique after sandblasting and acid etching treatment. The polished titanium specimens(P group)were used as control group, and sandblasted acid-etched titanium(SLA group)and tantalum-coated titanium(Ta group)were used as test groups. The micro-morphology and elemental composition of the titanium surface of each group were analyzed by scanning electron microscopy(SEM)and energy spectrometry(EDS). The hPDLSCs were inhibited on the surface of each group of specimens, and the proliferation activity of cells was measured by CCK-8 assay. After osteogenesis induction culture, alkaline phosphatase activity assay and alizarin red staining were performed. Osteogenic gene expression was detected by qPCR. Results Tantalum coating was successfully prepared on titanium specimens. The hPDLSCs were successfully isolated and identified. The results of CCK-8 experiment showed that after 3, 5 and 7 days of culture, the OD value of Ta group was significantly higher than that of SLA and P groups(P<0.05). The results of ALP assay showed that the difference between the three groups was not statistically significant at day 7;at day 14, the ALP activity in the Ta group was significantly higher than that in the P and SLA groups(P<0.01). Alizarin red staining showed that red calcified nodules were formed on the superficial side of the materials in all three groups, and the mineralized nodules in the SLA and Ta groups were significantly more than those in the P group. The qPCR data indicated that the expression levels of ALP, RUNX2, and OCN genes were significantly higher in the Ta group than in the P group(P<0.01), and the expression of RUNX2 and OCN genes were effectively higher than that in the SLA group(P<0.01). Conclusion Tantalum coating can promote the proliferation and osteogenic differentiation of periodontal stem cells.

Objective This study aims to explore the mechanical properties of cancellous bone at different tooth positions and at different levels of tooth roots, and to provide a basis for the establishment of an accurate constitutive alveolar bone model. Methods Human maxillary and mandibular bone collected from fresh corpses was divided into several independent cancellous bone cubes at different tooth positions(anterior and posterior regions)and different levels of the roots(cervical, middle and apical regions). After micro-CT imaging bone density analysis, uniaxial compression test was performed at a loading rate of 0.1 mm/min, and the stress-strain curve was linearly fitted. The elastic modulus was calculated and compared to see if there were differences in the elastic modulus of cancellous bone in different parts of the alveolar bone. Results Under uniaxial compression at 0.1 mm/min, the compressive stress-strain curve for human alveolar cancellous bone was non-linear, with moduli of elasticity ranging from 340 to 805 MPa for all parts of the human maxilla and 107 to 730 MPa for all parts of the mandible. The elastic modulus of cancellous bone in different parts of the alveolar bone was statistically different. The elastic modulus of maxillary and mandibular alveolar cancellous bone was greater in the anterior region than in the the posterior region(P<0.05), in the cervical region than in the middle of the root, and in the middle of the root than in the apical region(P<0.01). Conclusion The cancellous bone elastic modulus is greater in the anterior region than in the posterior, in the cervical region than in the middle, and in the middle region than in the apical. The mechanical properties of cancellous bone in human alveolar bone are influenced by the density of cancellous bone, the location of the root, and the root level.

Objective To compare the cleaning effect of three kinds of Er:YAG laser power parameters on smear layer and damage on root canals with different length and curvature. Methods One root of 144 extracted permanent teeth with single root canal were divided into short group and long group according to different root length, and each group was divided into 3 subgroups according to different root canal curvature: straight, moderate and severe. Each subgroup was divided into 4 groups according to different root canal cleaning methods: ultrasonic group, 0.3 W PIPS group, 0.6 W PIPS group, 0.9 W PIPS group (n=6). After the final irrigation, the root were split longitudinally into two parts and observed under a scanning electron microscope ( ×1 000). The laser's cleaning ability was evaluated according to the smear layer score and damage. Results The cleaning effect of the experimental groups (Er: YAG laser) was significantly better than that of the control group (ultrasonic) (P<0.05). ①At the coronal section of short root, while the power was set at 0.3 W, most of the dental tubules were opened; at 0.6 W, moderate and severe curvature groups' cleaning efficiency were significant improved; at 0.9 W, the cleaning efficiency had no difference with 0.6 W. However, micro-cracks were found on the dentin wall. At the apical section, the cleaning efficiency were improved by the increase of laser power, but it was worse than the coronal section (P<0.05). ②For the long root, most of the straight and moderate groups' dentin tubules at coronal section were opened at 0.3 W while the cleaning efficiency at the apical section was worse than that at coronal section. At 0.9 W, the cleaning efficiency of straight and moderate groups were improved (P<0.05), but the coronal micro-cracks appeared again without significant improvement of smear layer removal ability in the severe curvature group. Conclusion 0.3 W can be an appropriate power for short straight root while for the short moderate root, the power needs to reach 0.9 W. 0.9 W is fit for long straight and moderate root, but neither short nor long severe curvature root can achieve a good cleaning effect at 0.9 W.

Objective To evaluate the antimicrobial effects of different irrigants on the mixed infection of Enterococcus faecalis and Candida albicans in standard root canal models. Methods The mixed biofilm of Enterococcus faecalis and Candida albicans was inoculated into the standard root canal and cultured for 28 days. Canals were washed with 2.5% NaClO or 2% CHX and prepared with ProTaper NEXT, and normal saline was used as a blank control. After chemomechanical preparation, microbial reduction rates were calculated using colony-forming units(CFUs)counting methods; the depths of microbial inhibition in dentinal tubules were examined using a confocal laser scanning electron microscope(CLSM). Results The clearance rates of Enterococcus faecalis and Candida albicans in mixed infection root canals in 2.5% NaClO and 2% CHX groups were higher than those in normal saline group(P<0.05). CLSM observation showed that the inhibition depths of 2.5% NaClO group were significantly higher than those of 2% CHX group(P<0.05), while 2% CHX only inhibited microbes on the superficial dentine. Conclusion 2.5% NaClO exhibits better cleaning effect than 2% CHX on the mixed infection of Enterococcus faecalis and Candida albicans, which can be widely used in clinic.

Objective To evaluate the clinical outcomes of All-on-4 immediate loading implant restorations in edentulous patients. Methods A total of 30 All-on-4 patients with 144 implants who completed the treatment between November 2013 and August 2019 were included in this study. The 1-6 years outcome measurements, including survival rate of the implants and prostheses, marginal bone resorption of the implants, mechanical complications of the prostheses, patient satisfaction and quality of life scores were analyzed after implantation. Results Among the 30 patients, the implant survival rate and the restoration survival rate was 100%. There was no statistical difference in the comparison results of the marginal bone loss between axial and tilted implants in each time period. The bone loss stabilized within 2 or 3 years after implantation, and there was continuous bone loss during the follow-up period, but there was no significant change in bone resorption. One or more mechanical complications occurred in 13 restorations, accounting for 43.3%(13/30)of the total restorations, including temporary restorations fractured, abutment screws of restorations broken, retention screws loose, and restorations had one or more fractures. In terms of stability, psycho-social and chewing recovery, patient satisfaction score was relatively high;while for aesthetics, pain, and pronunciation effects, patient satisfaction score was relatively low. Conclusion The short-term clinical outcomes of All-on-4 immediate loading implant restoration technology in edentulous patients are reliable. However, more long-term clinical studies with high-quality large samples need to be conducted.

Objective To observe the anatomic morphology of the normal maxillary sinus using cone-beam computed tomography(CBCT)and evaluate its variation to age and gender, helping clinicians to understand the anatomy of the normal maxillary sinus and to anticipate the selection of treatment plans. Methods CBCT data of 480 patients were selected and divided into 4 groups according to age:18-24 years old group, 25-39 years old group, 40-54 years old group and ≥55 years old group. The CBCT data were imported into Mimics software to measure maxillary sinus volume(MSV), surface area, and the morphology of the maxillary sinus floor(MSF) bilaterally. The correlation with age and gender was analyzed using SPSS software. Results There was no significant difference in MSV and surface area between the left and right sides(P>0.05), and the MSV and surface area of males were higher than those of females(P<0.05). MSV was greater in the 18-24 and 25-39 age groups than in the other two groups, and the measurement of surface area was the greatest in the 18-24 age group(P<0.05). There was no significant correlation between gender and MSF morphology(P>0.05), but there was a significant correlation between age and MSF morphology(P<0.05). Conclusion The volume and surface area of the normal maxillary sinus are affected by age and gender and decrease with age, but the maxillary sinus morphology is symmetrical on the left and right side.

Objective To compare the clinical effects of strip autogenous bone block combined with GBR (guided bone regeneration) and GBR alone in horizontal bone augmentation. Methods Twenty patients who needed delayed implantation of horizontal bone augmentation were selected and divided into two groups. The study group(group A)was strip autogenous bone block combined with GBR, and the control group(group B) was GBR alone. Before operation(T₀), immediately after operation(T₁) and 6 months after operation(T₂), the width of different sections of alveolar ridge in the bone graft area was measured by cone beam computed tomography(CBCT). The graft success rate, bone increment, bone resorption rate and The VAS pain scale scores of two groups were evaluated. Results Six months after bone grafting, the success rate of two groups was 100%,andthe bone width in both groups was significantly increased. The increment of group A at 1 mm and 3 mm below the crest was more than that of group B, with a significant difference(P<0.05), while there was no significant difference at 6 mm and 9 mm below the crest(P>0.05). The absorption rate of group A was lower than that of group B at 1 mm, 3 mm and 6 mm below the crest, with a significant difference(P<0.05), while the bone absorption rate of two groups at 9 mm below the crest was similar, with no significant difference(P>0.05).There was no significant difference in pain scale scores between two groups(P>0.05). Conclusion For severe horizontal bone defect, application of strip autogenous bone block combined with GBR has a lower absorption rate at the crest and middle of alveolar ridge, and can get a better crest contour than that of GBR alone.

Objective To analyze the effects of esmketamine and sevoflurane inhalation regimens on hemodynamics and recovery quality in children undergoing oral day surgery under general anesthesia. Methods A total of 136 children with caries were selected from our hospital from September 2020 to July 2021. All patients were expected to receive daytime dental treatment under general anesthesia and divided into a control group and a study group according to the random throwing method. The control group was given esketamine anesthesia, and the study group was given non-intubation sevoflurane inhalation anesthesia. The operation-related conditions, MAP, HR, SpO₂ indexes, CHIPPS score, PAED score and the incidence of anesthesia-related adverse events at each perioperative period were compared between the two groups. Results The onset time of anesthesia and the time of fully awake in the study group were shorter than those in the control group (P<0.05). There was no significant difference in the levels of MAP, HR and SpO₂ at T₁ between the two groups (P>0.05). MAP and HR were lower than those of the control group at T₂, and the difference was significant (P<0.05). There was no significant difference in SpO₂ levels at T₁, T₂, and T₃ (P>0.05). The CHIPPS and PAED scores of the study group were significantly lower than those of the control group at 15 and 30 min after awakening. In terms of adverse reactions, the total incidence of adverse reactions in the study group was 2.90% (2/68), which was lower than 11.76% (8/68) in the control group, with a significant difference (P<0.05). Conclusion Compared with esmketamine, sevoflurane has better value and safety in children undergoing oral day surgery under general anesthesia. It has rapid onset of anesthesia and good recovery quality. At the same time, it is beneficial to maintain hemodynamic stability, reduce the risk of anesthesia-related adverse reactions such as respiratory depression and vomiting, and has more promotional value.

Objective To compare the clinical efficacy of maxillary protraction and Twin-block magnetic appliance in the treatment of mild-to-moderate skeletal Class Ⅲ malocclusion in the late stage of mixed dentition or early permanent teeth stage. Methods A total of 40 patients with mild-to-moderate skeletal Class Ⅲ malocclusion in thelate stage of mixed dentition or early permanent teeth stage were randomly divided into three groups. The first group of 20 patients received treatment with maxillary protraction appliance and the second group of 20 patients received treatment with Twin-block magnetic appliance. Sixteen patients in the third group with mild-to-moderate skeletal Class Ⅲ malocclusion who did not initiate treatment but were regularly followed up were selected as the control group, with an average age of 9 years and 5 months. Twenty cephalometric measurements were selected and the changes before and after treatment were analyzed by variance analysis and least-significant difference (LSD) test. Results There were significant statistical differences between group Ⅰ, group Ⅱ and the control group Ⅲ. Seven cephalometric measurements were significantly different between group Ⅰ and group Ⅱ(P<0.05). In the maxillary protraction group, the inclination of anterior teeth was increased; the overjet of anterior teeth and the molar relationship was improved. In the Twin-block magnetic appliance group, the A point moved down less; the mandibular plane(SNL-ML)rotated clockwise less, and the maxillary incisors erupted vertically more. Conclusion Both maxillary protraction and Twin-block magnetic appliance can promote maxillary development, but Twin-block magnetic appliance has more advantages in preventing labial inclination of anterior teeth and mesial movement of anchorage molars than maxillary protraction.

The jaw is constantly renewed and remodeled throughout the lifetime and is a crucial part of the stomatognathic system. The jaw homeostasis and repair of jaw injury are regulated by multiple cells and molecules, in which immune cells play an important role. Numerous studies have confirmed that the immune system could regulate the process of bone homeostasis and bone remodeling by direct and indirect pathways. This review summarizes the mechanisms of immune cells regulating bone homeostasis and bone reconstruction in order to provide ideas for future in-depth research.

Food impaction around implants is a common complication. To prevent horizontal food impaction, clinicians should not only strictly control the indications of implant restoration, but also formulate proper implant placement and restoration protocols. Besides, it is also of vital importance for clinicians to strengthen patients' awareness of oral health care, and provide professional mechanical debridement at regular intervals. Vertical food impaction often results from interproximal contact loss between implant-supported restorations and adjacent teeth. To prevent vertical food impaction, it is recommended to evaluate and adjust interproximal contacts and occlusion during the follow-up.

In 2020, Avila-Orti proposed that the peri-implant “supracrestal tissue height (STH)” consisted of gingival sulcus epithelium, junctional epithelium and connective tissue, which adhered to the surface of the implant, forming a soft tissue seal around the implant.The depth of implant placement, the connection of abutment and the different structure and chemical composition of implant surface can all affect the height and adhesion ofsupracrestal soft tissue. This article will review the formation and attachment of supracrestal soft tissue and related clinical methods to promote soft tissue adhesion.