Application of computer-aided design and 3D-printed template for accurate bone augmentation in the aesthetic region of anterior teeth.

PURPOSE: To explore the outcomes of bone augmentation in the aesthetic zone of the anterior teeth using computer-aided design and a 3D-printed template. METHODS: Ten patients with severe bone defects in the aesthetic zone of anterior teeth were included in the study; CT data were collected before surgery. The design of the osteotomy line in the bone defect area was determined under computer simulation. The position parameters and osteotomy line of the free bone were determined via virtual surgery. A 3D-printed template was prepared to guide the accurate placement of the bone graft. Reexamination was conducted to evaluate the position of the bone graft immediately after the operation and the resorbed capacity of the bone graft before implant restoration. RESULTS: The position of the bone graft was consistent with the preoperative design. The amount of bone graft resorbed was within the acceptable range three months after the operation, and the effect of implant restoration was satisfactory. CLINICAL SIGNIFICANCE: Use of computer-aided design and a 3D-printed template can be an effective approach for accurate bone augmentation in the aesthetic zone of the anterior teeth.

Single-cell transcriptomic analysis of the tumor ecosystem of adenoid cystic carcinoma.

Adenoid cystic carcinoma (ACC) is a malignant tumor that originates from exocrine gland epithelial cells. We profiled the transcriptomes of 49,948 cells from paracarcinoma and carcinoma tissues of three patients using single-cell RNA sequencing. Three main types of the epithelial cells were identified into myoepithelial-like cells, intercalated duct-like cells, and duct-like cells by marker genes. And part of intercalated duct-like cells with special copy number variations which altered with MYB family gene and EN1 transcriptomes were identified as premalignant cells. Developmental pseudo-time analysis showed that the premalignant cells eventually transformed into malignant cells. Furthermore, MYB and MYBL1 were found to belong to two different gene modules and were expressed in a mutually exclusive manner. The two gene modules drove ACC progression into different directions. Our findings provide novel evidence to explain the high recurrence rate of ACC and its characteristic biological behavior.

An evaluation of allogeneic freeze-dried concentrated growth factors biocompatibilityin vitroandin vivo.

This study evaluated the biocompatibility of allogeneic freeze-dried concentrated growth factors (AFD-CGFs)in vitroandin vivo.For thein vitroexperiments, bone marrow stem cells (BMSCs) were cultured in 10% fresh allogeneic concentrated growth factors (CGFs). AFD-CGF solution was used as the experimental group, and Dulbecco's modified Eagle medium was used as control. Transmission electron microscopy (TEM) showed that the cell ultrastructure was unchanged, and membranes were intact. Scanning electron microscopy, cell counting kit-8, and quantitative polymerase chain reaction indicated that BMSCs and differentiation were unchanged between AFD-CGFs versus control groups (allp> 0.05). Alkaline phosphatase activity was higher in CGF groups (peaked at 14 d) than in the control group. Regarding thein vivoexperiments, four beagles were used for surgery and the rest as controls. Beagles were sacrificed at 2 weeks to observe acute response and membrane absorption; at 12 weeks for wound healing and chronic damage to the liver. According to general observations and histology, the CGFs of all groups were absorbed 2 weeks afterin vivoimplantation. No sign of intolerance was observed. Histology showed a slight increase in immune cells appearing in the implantation area after 2 weeks. However, no or very few inflammatory and immune cells were detected 3 months after the operation. Based on the hematoxylin and eosin staining and TEM results, the ultrastructure of the liver tissue was unchanged. In general, the results suggest that AFD-CGFs are biocompatible and may be a promising option for tissue healing.

miR-148b-3p, miR-337-5p and miR-423-5p expression in alveolar ridge atrophy and their roles in the proliferation and apoptosis of OMMSCs.

MicroRNAs (miRNAs/miRs) have key roles in various physiological and pathological processes by regulating the expression of specific genes. The identification of miRNAs involved in bone metabolism may provide insight into the expression of genes associated with the development of alveolar ridge atrophy. In the present study, the miRNA expression profiles in alveolar ridge atrophy and normal tissue samples were investigated by miRNA microarray analysis. Among the 52 differentially expressed miRNAs identified, the expression levels of 20 selected miRNAs in the alveolar ridge atrophy and normal tissue samples were verified by reverse transcription-quantitative polymerase chain reaction. The results indicated that the expression levels of 11 miRNAs were significantly different between alveolar ridge atrophy and normal tissue samples; however, only three of them (miR-148b-3p, miR-337-5p and miR-423-5p) were previously reported to be involved in bone metabolism. In vitro, miR-148b-3p, miR-337-5p and miR-423-5p mimics promoted the proliferation and inhibited apoptosis of bone marrow mesenchymal stem cells from orofacial bone (OMMSCs), while antisense inhibitors of these miRNAs had the opposite effect. In conclusion, the present study indicated that these miRNAs are involved in the pathogenesis of alveolar ridge atrophy. miR-148b-3p, miR-337-5p and miR-423-5p promote the proliferation of OMMSCs and inhibit their apoptosis. The present results provide a novel perspective for understanding the pathogenesis of alveolar ridge atrophy.

MiR-92a regulates oral squamous cell carcinoma (OSCC) cell growth by targeting FOXP1 expression.

Increasing evidence indicates that microRNAs dysregulation contributes to the development and progression of various human cancers, including oral squamous cell carcinoma (OSCC). However, little is known about the potential role of microRNA-92a (miR-92a) in OSCC. Thus, the aim of this study was to investigate the effects of miR-92a expression on OSCC cell growth, apoptosis and tumorigenesis. Real-time quantitative polymerase chain reaction was used to detect the expression level of miR-92a in primary tumor tissues and OSCC cell lines. The effects of miR-92a on cell proliferation, cell cycle, apoptosis and tumorigenesis of OSCC cells were explored after miR-92a expression was increased or decreased in the UM1 and Tca-8113 cells, respectively. The 3'-untranslated region (3'-UTR) of FOXP1 combined with miR-92a was analyzed with dual-luciferase reporter assays. The level of miR-92a expression was significantly up-regulated in the OSCC tissues and cell lines. The up-regulation of miR-92a expression promoted UM1 cell proliferation, cell cycle progression in vitro and tumor growth in nude mice, but its expression reduction inhibited these processes and induced apoptosis in Tca-8113 cells. Additionally, miR-92a expression was inversely correlated with FOXP1 protein expression in the OSCC tissues and cell lines. Furthermore, FOXP1 was identified as a functional downstream target of miR-92a by directly targeting the 3'-UTR of FOXP1. These findings indicate that miR-92a may act as a tumor inducer in OSCC by suppressing FOXP1 expression, and it could serve as a potential therapeutic target for OSCC treatment.

Enhanced silver loaded antibacterial titanium implant coating with novel hierarchical effect.

In this study, we present a novel strategy for hierarchical antibacterial implant coating by controlling structural and componential features as regulators of surface bactericidal property. Anodized titanium dioxide nanotubes and self-polymerized polydopamine were both used as preliminary antibacterial agents with a significant positive effect on surface bioactivity. At the same time, the storage capacity of nanotubes and the in situ reduction activity of polydopamine can introduce large amounts of strong attached silver nanoparticles for enhanced stable antibacterial performance. The surface morphology, chemical composition, and hydrophilicity had been thoroughly characterized. The sustained silver release performances were continuously monitored. The successively in vitro inhibition on Staphylococcus aureus growth of titanium dioxide nanotube, polydopamine layer and silver nanoparticles demonstrated the hierarchical antibacterial property of the final silver nanoparticles-incorporated polydopamine-modified titanium dioxide nanotube coating (silver/polydopamine/nanotube). Moreover, the bioactivity investigation indicated the vital role of polydopamine-modified titanium dioxide nanotube coating on preserving healthy osteoblast activity at the implant interface. The unique hierarchical coating for titanium implant may be a promising method to maximize antibacterial capacity and maintain good cellular activity at the same time.

Evaluation of Mechanical Properties and Marginal Fit of Crowns Fabricated Using Commercially Pure Titanium and FUS-Invest.

This study investigated the mechanical properties and single crown accuracy of the tailor-made Fourth University Stomatology investment (FUS-invest) for casting titanium. Background. Current investment for casting titanium is not optimal for obtaining high-quality castings, and the commercially available titanium investment is costly. Methods. Titanium specimens were cast using the tailor-made FUS-invest. The mechanical properties were tested using a universal testing machine. Fractured castings were characterized by energy-dispersive spectroscopy. 19 titanium crowns were produced using FUS-invest and another 19 by Symbion. The accuracy of crowns was evaluated. Results. The mechanical properties of the titanium cast by FUS-invest were elastic modulus 125.6 ± 8.8 GPa, yield strength 567.5 ± 11.1 MPa, tensile strength 671.2 ± 15.6 MPa, and elongation 4.6 ± 0.2%. For marginal fit, no significant difference (P > 0.05) was found at four marker points of each group. For internal fit, no significant difference (P > 0.05) was found between two groups, whereas significant difference (P < 0.01) was found at different mark point of each group. Conclusions. The mechanical properties of titanium casted using FUS-invest fulfilled the ISO 9693 criteria. The marginal and internal fit of the titanium crowns using either the FUS-invest or Symbion were similar.

[Research on physical and mechanical properties, crown accuracy by using self- made FUS-invest dental investment].

PURPOSE: To evaluate the physical and mechanical properties of pure titanium castings cast by self- made FUS-invest dental investment, and evaluate casting accuracy. METHODS: Seven pure titanium castings were cast by self-made FUS-invest zirconium investment and analyzed using servo hydraulic dynamic experiment system (JJG139-83 standard), scanning electron microscope and energy spectrum analysis. Thirty-eight crowns of pure titanium were cast by two different methods. One cast by FUS-invest zirconium embedding material was used for experiment and the other cast by phosphate embedding material was used as control. Casting accuracy was assessed through measuring the difference value d at the marginal marker points and distance between casting pieces of wall and working modes of casting were examined under microscope. Scanning electron microscope with energy-dispersive spectrum (EDS) was used to analyze the status of composition of the casting surface. SPSS 17.0 software package was used to investigate the difference of two groups. RESULTS: ①Qualitative analysis of servo hydraulic dynamic experiment system showed various mechanical properties: elastic modulus (123.5±14.2) GPa, yield strength (569.3±16.5) MPa, tensile strength (668.4±16.1) MPa, elongation (4.5±0.2)%. EDS analysis of the fracture was observed at different depth (13, 25, 50, 350 µm) under the surface of pollution layer, a little Si and Fe with different atomic percentage was found but no Zr. ②No significant difference (P>0.05) was found between each group of four markers on the marginal fit, and internal fit, whereas significant difference (P<0.01) was found at different marker point. CONCLUSIONS: The mechanical properties of commercially pure titanium casting by self-made FUS-invest zirconium-based investment can meet the qualification of dental metal materials, although elongation was a little lower. Both the marginal adaptation and internal fit between the two groups had no significant difference. The mean marginal difference was 46 µm, the mean internal difference at axial angle was 56 µm and approximately 0 at axial wall.

Natural teeth-retained splint based on a patient-specific 3D-printed mandible used for implant surgery and vestibuloplasty: A case report.

RATIONALE: With respect to improving the quality of oral rehabilitation, the management of keratinized mucosa is as important as bone condition for implant success. To enhance this management, a natural teeth-retained splint based on a patient-specific 3-dimensional (3D) printed mandible was used in vestibuloplasty to provide sufficient keratinized mucosa around dental implants to support long-term implant maintenance. PATIENT CONCERNS: A 28-year-old male patient had a fracture of the anterior andible 1 year ago, and the fracture was treated with titanium. DIAGNOSES: The patient had lost mandibular incisors on both the sides and had a shallow vestibule and little keratinized mucosa. INTERVENTIONS: In the first-stage implant surgery, 2 implants were inserted and the titanium fracture fixation plates and screws were removed at the same time. During second-stage implant surgery, vestibuloplasty was performed, and the natural teeth-retained splint was applied. The splint was made based upon a patient-specific 3D-printed mandible. At 30-day follow-up, the splint was modified and reset. The modified splint was removed after an additional 60 days, and the patient received prosthetic treatment. OUTCOMES: After prosthetic treatment, successful oral rehabilitation was achieved. Within 1 year and 3 years after implant prosthesis finished, the patient exhibited a good quantity of keratinized gingiva. LESSONS SUBSECTIONS: The proposed splint is a simple and time-effective technique for correcting soft tissue defects in implant dentistry that ensures a good quantity of keratinized mucosa.

Alkalescent nanotube films on a titanium-based implant: A novel approach to enhance biocompatibility.

The interfacial pH value has a marked effect on cell viability because the pro-mineralization activity of osteoblasts increases at alkaline extracellular pH, whereas the pro-resorptive activity of osteoclasts increases under more acidic conditions. To obtain the more favorable alkaline interface, we developed a novel nanotube layer that was incorporated with magnesium oxide on a titanium implant substrate (MgO/NT/Ti) via ethylenediamine tetraacetic acid (EDTA) chelation. This facile immersion-annealing process successfully created a homogeneous magnesium oxide layer with sustained release kinetics and superior hydrophilicity according to the surface characterization and microenvironment measurement. The titania nanotubes on the substrate with an anatase phase exhibited a lower passivation current and a more positive corrosion potential compared with pure titanium, which guaranteed a reasonable corrosion resistance, even when it was wrapped with a magnesium oxide layer. In vitro cell cultures showed that MgO/NT/Ti significantly increased cell proliferation and alkaline phosphatase (ALP) activity. The resulting alkalescent microenvironment created by the MgO layer encouraged the cells to spread into polygonal shapes, accelerated the differentiation stage to osteoblast and induced a higher expression of vinculin. In summary, the incorporated alkalescent microenvironment of MgO/NT/Ti provided a viable approach to stimulate cell proliferation, adhesion, and differentiation and to improve the implant osseointegration.

[Effect of investment composition ratio for pure titanium crown and bridge on some mechanical properties of mould].

OBJECTIVE: To determine the optimal composition of a self-developing investment material by measuring physical and mechanical properties of mould. METHODS: L(9) (3(4)) orthogonal design was adopted. One hundred and fifty specimens with the size of 80 mm × 20 mm × 20 mm were prepared to measure the atmospheric temperature bending strength, high temperature bending strength and residual bending strength. Nine specimens with the size of 5 mm diameter 25 mm heigh were prepared to survey the thermal expansion curve from ambient temperature to 1150°C. RESULTS: Strengths were greatly affected by fine powder proportion in refractory and water/powder ratio. When the content of fine powder was 35% and water/powder ratio was 1:7.5, adequate atmospheric temperature strength and high temperature strength could be achieved. Moreover, the residual strength was moderate. The thermal extension curves of specimens in experiment group were almost similar. And the average linear expansion coefficient was (4 ∼ 5) × 10(-6)/°C. CONCLUSIONS: The three kinds of bending strength of self-developing investment material are compared with commercialized investment material for titanium casting when water/powder ratio and the content of fine powder are carefully controlled.

[Effect of investment for titanium crown and bridge on reactive layer of castings].

OBJECTIVE: To investigate the effect of self-developing investment (FUS-invest) on the reactive layer of titanium castings. METHODS: Three 10 mm x 10 mm x 1 mm pure titanium castings were founded using FUS-invest. Metallographical structure of reactive layer was observed. X-ray diffraction (XRD) and scanning electron microscope with energy-dispersive spectrum (EDS) were used to analyze the status of composition of the casting surface. Micro-Vickers hardness was measured. RESULTS: The metallograph indicated that the reactive layer was composed of coarse flake-shaped alpha phase of grains. The value of micro-Vickers hardness with the range 243 to 314 MPa had not significantly difference under the depth of 105 microm beneath the surface. The XRD pattern clearly showed the peaks of ZrO2, SiO2, Mg2TiO4 and TiO2. EDS analysis demonstrated that the main elements were Al, Si, Zr and Cl. CONCLUSION: FUS-invest is suited for pure titanium casting because of the thin reactive layer and less change to metallographical structure.

[Effects of the improved FUS-invest investment for zirconium-oxide titanium crown and bridge on the reaction layer].

OBJECTIVE: To investigate the effects of the improved FUS-invest investment for zirconium-oxide titanium crown and bridge on the reaction layer. METHODS: 10 mm x 10 mm x 1 mm titanium castings were invested. Spectrum analysis was done to its reaction layer, the metallographic examination was observed and Vickers hardness was measured. RESULTS: The reaction layer was not obvious by the metallographic examination. The layer with plenty of Si was hardly detectable. The needle crystal layer diffused distribution on the surface of the titanium matrix. The depth was about 55 microm. Spectrum analysis showed that the contents of Si and Zr decreased as the depth increased. The microhardness, which obviously decreased from the surface to the matrix, tended to be equal with the hardness of the matrix after the depth reached 75 microm from the surface. CONCLUSION: The thickness of the reaction layer of the improved FUS-invest investment for zirconium-oxide titanium crown and bridge was decreased to 55 microm from 85 microm, which was the thickness before improvement.

[The effect of casting techniques on the accuracy of titanium crown and bridge].

OBJECTIVE: To investigate the method of enhancing the accuracy of titanium crowns by improving the casting method. METHODS: A self-assembled die was used to fabricate 48 standardized wax crowns. The dies were averagely divided into two groups. 21 crowns were successfully fabricated from one group according to the improved techniques. 18 crowns were fabricated by traditional method. A reference mark was scribed 90 degrees apart at four sites on the margin of each wax pattern and respective die. The distance between the margins of the wax pattern and the die was measured under a stereomicroscope. Similar method was also applied to measure the margin of castings. The castings were longitudinally split through midline. The distance between the 4 points(B',C',D',E') selected in the inner part of the crown and the die was respectively examined. RESULTS: Castings acquired by the improved method were more complete and had smoother surface. Marginal discrepancy value had significant difference between the two groups. Value in experimental group was smaller. Distance from B',E' to die between the two groups had no significant difference, but the distance from C',D' to the die was significantly different. The experimental group was smaller. CONCLUSION: Standardized crowns fabricated by the improved titanium casting technique were more accurate, but special investment for titanium crowns and bridges should be developed to compensate the casting shrinkage of metal.