In tooth defect restoration , the technology of obtaining digital impression through intraoral scanning is used more and more frequently in clinical practice because of its simple, comfortable and fast characteristics. The accuracy of digital impression (including trueness and precision) is the key to final success of restoration. The scanning accuracy is different because of different scanning principles of various intraoral scanning equipment. In addition, the scanning scheme adopted in clinical operation, preparation quality and oral environment will all affect scanning accuracy. Understanding the principle of intraoral scanning and relevant influencing factors of scanning accuracy, and taking corresponding coping strategies in clinical operation can improve scanning accuracy, and then eventually improve the success rate of digital restoration of tooth defects.

Objective To explore the effect of gamma secretase inhibitor (Avagacestat) on inhibiting osteoclast formation and bone resorption to suppress the progress of osteoarthritis. Methods Bone marrow cavity macrophages (BMMs) of 6 weeks old C57 mice were extracted and induced for culture. IC₅₀ of Avagacestat on macrophages induced by M-CSF and RANKL was calculated by CCK8. Osteoclast formation test and function test were conducted to determine the inhibition of Avagacestat on osteoclast by setting 3 groups with drug concentration of 0, 120, 240 nmol/L and osteoclast progress-associated genes such as TRAP, C-fos, Cath-K were checked through RT-PCR in 3 groups. Then osteoarthritis mouse model was constructed by injecting LPS into the Articulatio genus. Bone resorption was examined by 3D bone reconstruction, and distribution of osteoclast was detected through HE staining and TRAP staining. Results At 24 h, 48 h and 96 h, the IC₅₀ of Avagacestat on osteoclasts were 493, 426 and 405 nmol/L, respectively. The cell TRAP and bone resorption test respectively certified that Avagacestat could inhibit the formation of osteoclast and bone resorption, and the inhibition of 240 nmol/L was significantly higher than that of 120 nmol/L. RT-PCR results also indicated that the expression of osteolysis-associated genes TRAP, C-fos, Cath-K was significantly inhibited after the addition of Avagacestat, and with the increasing concentration of Avagacestat, expression of these genes significantly declined. 3D bone reconstruction and TRAP staining showed that the number of osteoclasts increased significantly and osteolysis was enhanced in LPS-induced osteoarthritis model. Avagacestat significantly inhibited the number of osteoclasts, showing bone mineral density and bone trabecular number increasing but osteoclast number decreasing after Avagacestat added, statistically significant. Conclusion Avagacestat can inhibit the proliferation of osteoclasts and the expression of osteolytic genes and resorption in osteoarthritis, so it has the potential to be used as a drug for arthritis treatment.

Objective To investigate the influence of ferrule and crown-to-root ratio on fracture resistance of mandibular first premolars treated with prefabricated fiber post and core restoration. Methods Forty sound extracted mandibular first premolars with single root canal in each tooth, were cut 2.0 mm coronal to the buccal cemento-enamel junction for residual root models. The roots were divided into five groups (n=8) at random. Simulated surgical crown lengthening procedures were done in the cervical region of the roots to provide ferrule lengths of 0.0 mm, 1.0 mm, 2.0 mm, 3.0 mm and 4.0 mm for groups A0 to A4 respectively. The corresponding crown-to-root ratios of each group were 0.62, 0.75, 0.91, 1.10 and 1.33 respectively. A glass fiber post-and-core combined with a cast Co-Cr alloy crown was used for the restoration of each root. Each specimen was embedded to a height 2.0 mm below the crown margin from the apical surface in an acrylic resin block and was loaded in a universal testing machine at a 135° angle to its long axis. The fracture loads and fracture patterns of the specimen were recorded and analyzed by SPSS software. Results Fracture loads of A0 to A4 groups were (0.54±0.09), (1.03±0.11), (1.06±0.17), (0.85±0.11), (0.57±0.10) kN. When a 1.0-2.0 mm ferrule was prepared in the cervical region of residual root and the crown-to-root ratio was less than 1, the fracture resistance of teeth increased significantly compared with the group without ferrule (P＜0.05). When the height of ferrule was more than 3.0 mm and the crown-to-root ratio was greater than 1, the fracture resistance of teeth decreased significantly (P＜0.05). Conclusion Different ferrule heights and crown-to-root ratios can significantly affect the fracture resistance of residual teeth. To ensure a better fracture resistance of mandibular first premolars, a 1.0-2.0 mm ferrule should be prepared in the cervical root and the crown-to-root ratio of teeth after restoration should be controlled within 1.

Objective To compare the effects of five different removal methods of residual adhesive on enamel and brackets′ shear bond strength(SBS). Methods Sixty-six isolated premolars were randomly divided into 6 groups. Group A:blank group; Group B:diamondbur; Group C:green sandstone; Group D:slow tungsten carbide bur; Group E:slow tungsten carbide bur +tooth polishing cup; Group F:slow tungsten carbide bur + silicon particle. The same number of adhesive samples in each group were ground by the methodabove, and the operation time was recorded. The enamel surface was qualitatively and quantitatively evaluated by scanning electron microscope (SEM) and surface roughness instrument. After bonding metal brackets, the SBS of brackets in each group was measured by universal mechanical tester, and the adhesive residual index (ARI) was analyzed. Results The removal efficiency of group B and C was higher, and that of group E was the lowest. SEM showed that the enamel morphology of group F was closest to group A. The roughness of group F was the lowest ((0.48±0.13)μm), which had no statistical difference with group A (P＞0.05). The SBS of group D was the highest ((16.61±1.99)MPa), which was statistically higher than group A (P<0.05). There was no significant difference in ARI index among all groups after bracket removal (P＞0.05). Conclusion The removal efficiency of diamondburs and green sandstone is high, but they have great damage to enamel; slow tungsten carbide bur combined with silicon particle has the lowest damage to enamel, and the removal efficiency is acceptable. The SBS of the bracket treated with slow tungsten carbide bur is the highest.

Objective To study the regulatory effect of miR-155 on osteogenic differentiation of periodontal ligament stem cells (PDLSCs) in inflammatory microenvironment. Methods PDLSCs were cultured and divided into control group, tumor necrosis factor group-α(TNF-α) group, miR-negative control (NC) group, TNF-α+miR-NC group, TNF-α+miR-155 inhibitor group and miR-155 group according to different treatment methods. Fluorescence quantitative PCR was used to detect miR-155, recombinantrunt related transcription factor 2 (Runx2), osteocalcin (OCN), collagen Ⅰ (Col-Ⅰ),bone morphogenetic protein 5 (BMP5) and bone morphogenetic protein 10 (BMP10) expression levels; Western blot was used to detect Runx2, OCN, Col-Ⅰ, BMP5, BMP10 protein expression; alizarin red staining was used to detect the formation of calcium nodules in cells; the double luciferase reporter gene was used to verify that miR-155 targeted BMP5 and BMP10. Results Compared with the control group, the expression level of miR-155 in PDLSCs in the TNF-α group increased; the mRNA and protein expression levels of Runx2, OCN, Col-Ⅰ and the formation of calcium nodules decreased (P＜0.05). Compared with the miR-NC group, the mRNA and protein expression levels of Runx2, OCN and Col-Ⅰ and the formation of calcium nodules in PDLSCs in the TNF-α+miR-NC group were decreased (P＜0.05). Compared with the TNF-α+miR-NC group, the mRNA and protein expression levels of Runx2, OCN and Col-Ⅰ and the formation of calcium nodules in PDLSCs in the TNF-α+miR-155 inhibitor group increased (P＜0.05). miR-155 negatively regulated the expressions of BMP5 and BMP10. Conclusion The expression of miR-155 in PDLSCs increases in inflammatory microenvironment. Knocking down miR-155 promotes the osteogenic differentiation of PDLSCs in inflammatory microenvironment. Targeting BMP5 and BMP10 is the relevant molecular mechanism.

Objective To investigate the effects of recombinant human amelogenin(rhAm) on angiogenesis of human umbilical vein endothelial cell(HUVEC) in vitro. Methods HUVEC were cultured in vitro. The effect of different concentrations of rhAm(0.1, 10.0, 50.0, 100.0 μg/mL rhAm) were compared with control group. The proliferation of HUVEC was investigated via MTT assay. The migration of HUVEC was investigated via scratch assay. Expression of angiogenesis-related genes and proteins were measured via real-time PCR and western blotting. The angiogenic structure formation of HUVEC was investigated via tube formation assay. Results The proliferation of HUVEC was stimulated by rhAm at concentration of 0.1 μg/mL and 10.0 μg/mL(P＜0.05), while inhibited at concentration of 100.0 μg/mL (P＜0.01). At concentration of 10.0 μg/mL, rhAm stimulated HUVEC migration in scratch assay(P＜0.01). According to the result of real-time PCR, the mRNA expression of intercellular cell adhesion molecule-1 (ICAM-1)(P＜ 0.01) and E-selectin (P＜0.05) were increased by rhAm at concentration of 10.0 μg/mL; the mRNA expression of vascular endothelial growth factor receptor(VEGFR)-1 and VEGFR-2 had a trend of up-regulation but no statistical difference. According to the result of western blotting, the protein expression of ICAM-1(P＜0.01)was increased by rhAm at concentration of 10.0 μg/mL, while the protein expression of VEGFR-1, VEGFR-2 and E-selectin had a trend of up-regulation but no statistical difference. RhAm induced the formation of angiogenic structure in vitro. Conclusion Results of the present in vitro study show the potential influence of rhAm on the angiogenic activity of HUVEC at a lower concentration, which may play an important role in periodontal tissue regeneration.

Objective To analyze the clinical and histopathological characteristics of oral lichen planus (OLP) complicated with type 2 diabetes mellitus (T2DM) through case-control study. Methods One hundred and four patients were divided into OLP group and OLP+T2DM group and their basic information, clinical types and REU scores of OLP were collected. Histopathological manifestations were described by two pathologists. Clinical and histopathological manifestations between the two groups were analyzed by SPSS 24.0. Results The prevalence of erosive OLP and REU score in OLP+T2DM group were significantly higher than those in OLP group (P＜0.001). After one month follow-up, REU score of OLP patients taking hypoglycemic drugs decreased significantly (P＜0.001), and that of OLP patients with ideal blood glucose control (P＜0.01) decreased significantly. Logistic regression analysis showed that: high REU score, erosion type, dense lymphocyte infiltration, unclear lymphocyte infiltration zone, severe inflammation in the basal layer, and presence of fibrin in the basal layer (OR=1.58, 37.15, 8.49, 10.16, 3.94, 4.35) were typical characteristics of OLP with T2DM. Conclusion OLP patients with T2DM have more severe clinical lesions and higher degree of tissue destruction. A personalized plan should be made to obtain better treatment effect.

Objective To investigate the clinical necessity of periodontal minimally invasive non-surgical therapy (MINST) in upper anterior teeth of patients with thin gingival phenotype. Methods Eighteen cases of grade Ⅲ and Ⅳ periodontitis with thin gingiva, who visited the Department of Periodontology of the Affiliated Stomatological Hospital of Nanjing Medical University from May 2020 to September 2021,were recruited and divided into two groups randomly. Their upper anterior teeth were treated with MINST (MINST group) or conventional subgingival scaling and root planing (SRP group). Changes of clinical parameters, such as probing depth (PD), clinical attachment loss (CAL), gingival recession (GR) and bleeding on probing (BOP) positive rates, were examined and compared between baseline and 3 and 6 months after therapy, as well as intergroup differences. Patients′ perception of discomfort/pain experienced during and after therapy was evaluated using visual analog scale (VAS) immediately and 7 d after procedure. After 6 months, patients′ perception regarding outcomes of the therapy wasalso measured by VAS in the same way. In addition, patients′ aesthetic satisfaction of the treated teeth was also recorded. Results Regardless of PD at the baseline, both groups had significant changes in PD, CAL, BOP positive rates and GR (P＜0.01). For sites of 4 mm≤PD≤6 mm, at 6 months after operation, change values of GR in the SRP group were greater than those in the MINST group (P=0.035). Also, only in SRP group, higher GR values were observed after 6 months compared to measurements after 3 months (P＜0.001). For sites with PD>6 mm, intergroup analysis showed that change values of PD and CAL in MINST group were higher than those in SRP group(P＜0.01). At 6 months after operation, change values of GR in SRP group were higher than those in MINST group(P=0.014). In addition, at 6 months postoperatively, further changes in PD values in both groups (P＜0.05) and in GR values (P=0.025)in SRP group were observed, compared to 3 months. In addition, the complaint of discomfort/pain and root hypersensitivity during the first post-therapy week was more severe in SRP group(P＜0.05), and no significant differences in the perception of therapy outcomes and aesthetic satisfaction levels of the treated teeth were observed between groups. Conclusion For upper anterior teeth with thin gingiva, especially for sites with PD>6 mm, MINST presents obvious advantages in PD reduction, CAL gain, maintaining position of the gingival margin and improving post-operative comfort experience of patients. Therefore, it is necessary to use MINST to achieve better periodontal health. However, it cannot be considered that MINST can achieve higher aesthetic evaluation from patients.

Objective To assess the clinical efficacy of invisible mandibular-advancement appliances on skeletal Class Ⅱ teenagers with Twin-Block as the control. Methods Forty-nine patients were involved in the retrospective study (21 in invisible group and 28 in TB group), whose lateral cranial radiographs taken before and after treatment were traced and analyzed. Dental, skeletal indexes and Holdaway analysis results of two groups were statistically compared. Results After treatment, SNB increased significantly in both groups. Increase in invisible group (ΔT=3.18±1.67) was significantly larger than that in TB group (ΔT=1.73±1.53) (P=0.013). ANB and OJ, meanwhile, decreased with no statistical difference. But in ANB, invisible group (ΔT=-2.76±1.48) showed a more obvious trend of decreasing than TB group (ΔT=-2.40±1.33). The invisible group also revealed better control of incisors′ inclination as well as a trend of decreasing in mandibular plane angle. Both groups demonstrated major improvement of patients′ profiles according to Holdaway analysis. Conclusion Invisible mandibular-advancement appliances display a similar effect of mandibular advancement, which is confirmed in the treatment of skeletal Class Ⅱ patients with TB. In addition, the invisible group has an advantage when a control of frontal teeth and vertical growth pattern is needed, while TB is more efficient in inducing the mandibular ramus. Both appliances could significantly improve soft tissue protrusion.

Objective To study the relationship between bone mass of space missing mandibular first molar and bone loss of the mandibular second molars moved into the space, and to provide reference for risk prediction and prognosis in clinical treatment. Methods Fifty orthodontic patients with mandibular first molar loss were included in the study. Patients were treated with bracket, and the space was closed by mesially moving molars with the aid of implant anchorage. Cone-beam CT was taken and bone mass was measured before and after treatment. SPSS22.0 statistical software was used to analyze the data. Results The mean bone height loss of mandibular second molars at seven out of eight sites was less than 1 mm. Moreover, 34.5% of all sites had bone height increase, and 90% molars had sites with bone height increase. The height and width absorption of alveolar bone in space missing mandibular first molar had no significant correlation with the bone height loss of the mandibular second molar moved into space. Conclusion Closing the space missing mandibular first molar by orthodontic mesial movement of adjacent molars will not cause severe bone loss, and even the increase of bone height may be obtained at some sites. Risk of treatment cannot be predicted through the absorption of alveolar bone in the tooth missing area, and incremental bone surgery is unnecessary before treatment.

Patients with skeletal Class Ⅱ often have airway problems in varying degrees, such as obstructive sleep apnea and hypopnea syndrome (OSAHS). This article reports a case of an adult male patient with osseous high-angle Class Ⅱ combined with OSAHS and bilateral temporomandibular joint anterior disc displacement without reduction treated with digital multidisciplinary treatment. After treatment, the patient′s OSAHS symptoms improved significantly. His micrognathia was corrected; facial soft tissue profile was also improved, and joint symptoms were controlled. This case shows that digital-guided multidisciplinary treatment combining respiratory medicine, oral and maxillofacial surgery and orthodontics, can achieve good therapeutic effects on this kind of patients.

Hydrogel is a three-dimensional network polymer formed by chemical and/or physical crosslinking in aqueous solution. Hydrogels often have high water absorption and water retention, and their highly hydrated properties are similar to those of extracellular matrix, which endows hydrogels with excellent biocompatibility. In addition, many hydrogels have biological functions such as anti-inflammatory, anti-oxidation and anti-cancer, so hydrogels have great potential for application in biomedicine. At present, hydrogels play an important role in tissue engineering scaffolds, drug carriers and biomedical devices. In this paper, basic properties of hydrogels and hydrogels commonly used in biomedicine are introduced, and the application of hydrogels in biomedicine is emphasized. Present situation of its application is summarized, and problems to be overcome in further clinical transformation of hydrogels are discussed.

The anterior zone is critical for oral aesthetic therapy, and adjusting the shape and position of anterior teeth is an important part of systematic aesthetic therapy. In clinical diagnosis and treatment, the dentist expects to restore natural teeth shape to coordinate with facia shape; to close anterior tooth space and adjust midline position to make the bow beautiful and symmetrical; to coordinate the relationship between dental arch and gingival and buccal tissue through vertical and horizontal control to achieve a beautiful smile. Perfect aesthetic treatment of anterior teeth requires the intervention of multi-disciplines and multiple treatment methods, and cultural background and aesthetic habits of patients should be regarded to achieve the best treatment effect. Digital diagnosis and treatment technology provides a guarantee for pre-treatment aesthetic analysis and prediction and post-treatment aesthetic evaluation. Based on the latest research at home and abroad, in this paper, both the anterior teeth’s position and shape and the relationship between dentition and gingival, buccal soft tissue are considered to summarize aesthetic considerations of anterior zone in oral treatment, so as to provide reference for oral treatment planning in aesthetic zone.

Fibromodulin is a small leucine-rich proteoglycan. It plays an important physiological role in the formation and maturation of dental tissue, the development of alveolar bone and the composition of joint structure. It also participates in the occurrence of periodontal disease, caries, temporomandibular joint disease and other pathological states. This article reviews the physiological function, pathological effect and potential clinical application of fibromodulin in oral diseases.

Dental pulp stem cells (DPSCs) are a kind of adult stem cells with high proliferation and multi-directional differentiation potential. They are rich in sources, convenient for extraction and less controversial in ethics. Because of its potential of multi-directional differentiation, it can be induced into neuronal differentiation under certain conditions, and has a broad application prospect in the repair of nerve injury and the treatment of neurogenetic diseases. Neurotrophins (NT) are a kind of protein molecules produced by innervated tissues or cells that can promote axonal growth and facilitate the differentiation and survival of nerve cells. It can be divided into neurotrophic factors (NTFs) family, glial cell line-derived neurotrophic factor (GDNF) family, interleukin-6 (IL-6) cytokine family, fibroblast growth factor (FGF) family and so on. NT, as a nutritional factor in promoting nerve cell differentiation, can also promote stem cell neuronal differentiation. It has a certain guiding effect on the neuronal differentiation of DPSCs in vitro and in vivo. This paper briefly introduces the signal transduction role of NT in promoting neuronal differentiation, and summarizes the effect and application prospect of NT on nerve differentiation of DPSCs.

Clear aligners have significant advantages in maxillary molar distalization. However, due to various factors such as different maxillary anatomical structure types and patient compliance, the actual distal movement of upper molar is inconsistent with design. It affects orthodontic treatment outcome. This article reviews basic characteristics of patients, difference in anatomical structures of maxillary molars and treatment design to provide a reference to upper molar distalization design for orthodontists, so as to improve movement efficiency.

After Bolton, Chinese scholars have carried out a series of related studies to explore the effect of extraction mode of premolars on Bolton ratio. However, there are both consensus and differences in relevant studies, and the standard for optimal over-all ratio after the extraction of four premolars in Chinese hasn′t been established. This paper summarizes progress of relevant research, aiming to provide reference for further research and clinical practice.

As a basic tool of oral aesthetics, digital smile design has been used by more and more stomatologists for clinical diagnosis and treatment, which can be combined with traditional model technology and other digital tools. It promotes the communication between doctors and patients, doctors and technicians and among doctors, and significantly improves the accuracy, predictability, implementation efficiency and success rate of treatment. In addition to being widely used in the field of oral restoration, digital smile design can be also combined with periodontitis, orthodontics, maxillofacial surgery and other disciplines for comprehensive treatment. This paper reviews the present situation and development of digital smile design in anterior tooth aesthetics.