OBJECTIVES: This study aims to use 3D prin-ting technology based on the principle of stereo lithography apparatus (SLA) to shape dental lithium disilicate ceramics and study the effects of different slurry proportions on the microstructure and properties of heat-treated samples. METHODS: The experimental group comprised lithium disilicate ceramics manufactured through SLA 3D printing, and the control group comprised lithium disilicate ceramics (IPS e.max CAD) fabricated through commercial milling. An array of different particle sizes of lithium disilicate ceramic powder materials (nano and micron) was selected for mixing with photocurable acrylate resin. The proportion of experimental raw materials was adjusted to prepare five groups of ceramic slurries for 3D printing (Groups S1-S5) on the basis of rheological properties, stability, and other factors. Printing, debonding, and sintering were conducted on the experimental group with the optimal ratio, followed by measurements of microstructure, crystallographic information, shrinkage, and mechanical properties. RESULTS: Five groups of lithium disilicate ceramic slurries were prepared, of which two groups with high solid content (75%) (Groups S2 and S3) were selected for 3D printing. X-ray diffraction and scanning electron microscopy results showed that lithium disilicate was the main crystalline phase in Groups S2 and S3, and its microstructure was slender, uniform, and compact. The average grain sizes of Groups S2 and S3 were (559.79±84.58) nm and (388.26±61.49) nm, respectively (P<0.05). Energy spectroscopy revealed that the samples in the two groups contained a high proportion of Si and O elements. After heat treatment, the shrinkage rate of the two groups of ceramic samples was 18.00%-20.71%. Test results revealed no statistical difference in all mechanical properties between Groups S2 and S3 (P>0.05). The flexural strengths of Groups S2 and S3 were (231.79±21.71) MPa and (214.86±46.64) MPa, respectively, which were lower than that of the IPS e.max CAD group (P<0.05). The elasticity modulus of Groups S2 and S3 were (87.40±12.99) GPa and (92.87±19.76) GPa, respectively, which did not significantly differ from that of the IPS e.max CAD group (P>0.05). The Vickers hardness values of Groups S2 and S3 were (6.53±0.19) GPa and (6.25±0.12) GPa, respectively, which were higher than that of the IPS e.max CAD group (P<0.05). The fracture toughness values of Groups S2 and S3 were (1.57±0.28) MPa·m^0.5 and (1.38±0.17) MPa·m^0.5, respectively, which did not significantly differ from that of the IPS e.max CAD group (P>0.05). CONCLUSIONS The combination of lithium disilicate ceramic powders with different particle sizes can yield a slurry with high solid content (75%) and suitable viscosity and stability. The dental lithium disilicate ceramic material is successfully prepared by using 3D printing technology. The 3D-printed samples show a small shrinkage rate after heat treatment. Their microstructure conforms to the crystal phase of lithium disilicate ceramics, and their mechanical properties are close to those of milled lithium disilicate ceramics.
Printing, Three-Dimensional ; Dental Porcelain/chemistry* ; Ceramics/chemistry* ; Materials Testing ; Particle Size

Intracranial aneurysms in children are rare in clinical practice.Its pathogenesis is not clear,and the treatment method has many controversies.The authors reported a case of pediatric intracranial aneurysms associated with neurofibromatosis type Ⅰ treated with two flow diverters,and reviewed relevant literatures,hoping to provide a useful reference for exploring the treatment of pediatric intracranial aneurysms.

Guided bone regeneration technology applied in alveolar bone defect regeneration is based on the barrier function and space maintenance of the barrier membrane. Therefore, traditional development strategies for barrier membranes focus on their physical barrier function, degradation characteristics and biocompatibility to avoid immunogenicity. However, not only does the barrier membrane passively block connective tissue, it is recognized as a “foreign body”that triggers a persistent host immune response, known as a foreign body reaction. The theories of osteoimmunology reveal a close relationship between the immune system and bone system and emphasize the role of immune cells in bone tissue-related pathophysiological processes. Based on these findings, we propose a novel development strategy for barrier membranes based on immune microenvironment regulation: by manipulating mechanical properties, surface properties and physiochemical properties, barrier membranes are endowed with an improved immunomodulation ability, which helps to regulate immune cell reactions to induce a favorable local immune microenvironment, thus coordinating osteogenesis and osteoclastogenesis as well as barrier membrane degradation to increase the efficiency of barrier membranes in GBR applications. In this paper, we review the development of barrier membranes and their close relationship to the immune microenvironment concerning bone regeneration and membrane degradation. Additionally, the outcomes of research on barrier membranes based on the regulation of the immune microenvironment have been summarized to improve the osteogenesis efficiency of barrier membranes and solve the problem of the regeneration and repair of bone defects, especially alveolar bone defects.

Objective To compare the efficacy of different target concentrations of etomidate in combination with midazolam,fentanyl and rocuronium used to induce anesthesia for tracheal intubation.Methods Eighty ASA Ⅰ or Ⅱ and Mallampati Ⅰ or Ⅱ patients of both sexes,aged 25-50 yr,weighing 57-76 kg,scheduled for elective non-cardiac surgery under general anesthesia,were randomly allocated into 4 groups according to the target effect-site concentration of etomidate (n =20 each) ∶ 0.5 μg/ml group (group E0.5),0.7 μg/ml group (group E0.7),0.9μg/ml group (group E0.9) and 1.1 μg/ml group (group E1.1).The patients were unpremedicated.Anesthesia was induced with midazolam 0.05 mg/kg,fentanyl 3 μg/kg,rocuronium 0.6 mg/kg and etomidate given by target-controlled infusion.When the effect-site concentration of etomidate reached 0.5,0.7,0.9 or 1.1 μg/ml,endotracheal intubation was performed.Auditory evoked potential index was recorded before induction of anesthesia (baseline),immediately before intubation,during insertion of the laryngoscope,and at 1,3 and 5 min after intubation.Myoclonus,injection pain,the requirement for vasoactive agents and burst suppression (BS) were recorded during induction of anesthesia.Results Compared with group E0.5,the requirement for urapidil was significantly decreased in group E0.7,the requirement for esmolol and urapidil was significantly decreased and the incidence of BS was increased in group E0.9,the requirement for esmolol and urapidil was significantly decreased,and the requirement for atropine and ephedrine and incidence of BS were increased in group E1.1 (P ＜ 0.05).The incidence of BS was significantly higher in group E0.9,and the requirement for atropine and incidence of BS were significantly higher in group E1.1 than in group E0.7 (P ＜ 0.05).The incidence of BS was significantly higher in group E1.1 than in group E0.9 (P ＜ 0.05).There was no significant difference in auditory evoked potential index and incidences of myoclonus and injection pain among the four groups (P ＞ 0.05).Conclusion The optimum target concentration of etomidate is 0.7μg/ml when combined with midazolam,fentanyl and rocuronium used to induce anesthesia.

Objective To evaluate the accuracy of auditory evoked potential index (AAI) in monitoring the anesthetic depth during isoflurane anesthesia.Methods Thirty ASA Ⅰ or Ⅱ patients aged 18-55 years and undergoing elective surgery under general anesthesia were enrolled in this study. The patients were unpremedicated. Anesthesia was induced with midazolam 0.05 mg/kg, fentanyl 3 μg/kg and propofol 1 mg/kg. Tracheal intubation was facilitated with recuronium 0.1 mg/kg. The patients were mechanically ventilated (VT:40 mm Hg. Anesthesia was maintained with isoflurane inhalation and intermittent intravenous boluses of vecuronium. Isoflurane was started with high-flow (FGF, 3 L/min) for 12 min followed by low-flow (LGF, 0.5 L/min). The inspired isoflurane concentration was set at 3%. The electrocardiogram (ECG), mean arterial pressure (MAP), heart rate (HR), pulse oxygen saturation (SpO2), end-tidal isoflurane concentration and AAI were continuously monitored during anesthesia and recorded before induction of anesthesia (baseline, To ), immediately after induction (T1), immediately before isoflurane inhalation (T2), at 3 min(T3), 6 min (T4), 9 min (T5) and 12 min (T6) during high-flow wash-in and at the end-tidal isoflurane concentrations of 0.8 MAC (T7), 1.0 MAC (T8) and 1.3 MAC (T9) during low-flow inhalation of isoflurane, respectively.Results AAI decreased gradually while the end-tidal isoflurane concentration increased during high-flow wash-in. And AAI was negatively correlated with the end-tidal isoflurane concentrations ( r = -0.896, P ＜ 0.01 ) during low-flow inhalation of isoflurane anesthesia.