In vitro evaluation of positioning accuracy of trephine bur at different depths by dynamic navigation / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the accuracy of trephine bur drilling at different depths guided by dynamic navigation system in 3D printing in vitro model.@*METHODS@#A model at the depth of 5 mm, 10 mm, and 15 mm from the outer surface of which hemispherical cavities was reserved and the 3D printing technology was used to make the standardized model with Veroclear resin. The cone beam CT (CBCT) was taken and the data were imported into the dynamic navigation software (DCARER, China) to establish navigation path programming. Under the guidance of dynamic navigation, a trephine bur with a diameter of 4.5 mm was used to complete the access operation. At each depth, 10 approaches were completed. The postoperative model CBCT was taken. The approach trajectory under navigation was reconstructed and compared with the designed path. The two-dimensional distance deviation, depth deviation, three-dimensional distance deviation, and angle deviation between the actually prepared path and the designed path were calculated.@*RESULTS@#At the depth of 5 mm, the two-dimensional distance deviation between the end position of the prepared path and the designed path was (0.37±0.06) mm, the depth deviation was (0.06±0.05) mm, the three-dimensional distance deviation was (0.38±0.07) mm, and the angle deviation was 2.46°±0.54°; At the depth of 10 mm, the four deviations between the end position of prepared path and the designed path were (0.44±0.05) mm, (0.16±0.06) mm, (0.47±0.05) mm, and 2.45°±1.21°, respectively; At the depth of 15 mm, the four deviations were (0.52±0.14) mm, (0.16±0.07) mm, (0.55±0.15) mm, and 3.25°±1.22°, respectively. With the increase of entry depth, the three-dimensional and depth accuracy of dynamic navigation system decreased (P < 0.01), and the positioning angle deviation had no relation with the entry depth (P>0.01).@*CONCLUSION@#Dynamic navigation technology can achieve high positioning accuracy in the depth range of 15 mm, but its deviation increases with the increase of entry depth.

Controlled release and cytobiology of recombinant human parathyroid hormone 1-34 mediated by hyaluronic acid thermo-sensitive hydrogels / 药学学报

The bone formation promoter recombinant human parathyroid hormone 1-34 [PTH (1-34)] has a short half-life and low bioavailability. In this study, we prepared a biodegradable and temperature-sensitive hyaluronic acid-poly-N-isopropyl acrylamide (AHA-g-PNIPAAm), and further investigated its effects of PTH (1-34) release and cell behavior as drug carrier. The structure of AHA-g-PNIPAAM was confirmed by hydrogen nuclear magnetic resonance spectroscopy and infrared spectroscopy. Next, PTH (1-34) loaded thermo-sensitive hydrogels were prepared by physical swelling method and their stability was investigated. The morphology of hydrogel was observed by scanning electron microscope. The minimum critical transition temperature and drug release behavior of hydrogels were investigated by ultraviolet spectrophotometry. The tetrazolium-based colorimetric assay (MTT assay) was used to investigate the toxicity and proliferation effects of PTH (1-34)-loaded thermo-sensitive hydrogel on mouse mononuclear macrophage RAW264.7 and mouse precranial osteoblasts MC3T3-E1. The effect of PTH (1-34)-loaded thermo-sensitive hydrogel on the differentiation of RAW264.7 was investigated by the tartrate-resistant acid phosphatase assay. The results showed that the PTH (1-34)-loaded thermo-sensitive hydrogel prepared in this study displayed regular three-dimensional honeycomb structure, and had good stability, thermo-sensitivity and sustained and controlled release properties, which could promote the proliferation of MC3T3-E1 cells more effectively and inhibit the differentiation of RAW264.7 into osteoclasts.

Preparation of triptolide-loaded dissolving microneedles and its transdermal penetration / 中国中药杂志

Triptolide(TP), the main active and toxic component of Tripterygium wilfordii, has the limitations of low bioavailability, poor absorption, low concentration in plasma, and small lethal dose. Microneedle(MN), the hybrid of hypodermic needle and transdermal patch, is a physical penetration-enhancing system. Dissolving microneedles(DMNs) can be tailored to specific needs of degradation rate. In this study, the TP-loaded DMNs(DMNs-TP) were prepared with the two-step centrifugation method. The optimal ratio of PVA to PVP K30, water content in matrix solution, demoulding method, and plasticizer for preparing DMNs were investigated with the indexes of formability and mechanical strength. The drug loading capacity was determined by HPLC and morphological characteristics were observed under an optical microscope. The mechanical properties were investigated by H&E staining and Franz diffusion cell was used to detect the in vitro skin permeation characteristics. Through the experiment, we confirmed that the optimal backing material should be PVA and PVP K30(3∶1) and the optimal ratio of matrix material to water should be 3∶4. The prepared DMNs-TP were pyramidal with smooth surface and length of approximately 550 μm. Each patch(2.75 cm~2) had the drug loading capacity of(153.41±2.29) μg, and TP was located in the upper part of the needle. The results of in vitro skin permeation assay demonstrated that the cumulative penetration of TP in DMNs-TP reached 80% in 24 h, while little TP solution penetrated the skin, which proved that DMNs promoted the transdermal delivery of TP.

A six-herb Chinese medicine composition ointment as a promising candidate for treatment of hypertrophic scars / 中草药·英文版

Objective: To study the anti-hypertrophic scar effect of the six-herb Chinese medicine composition (SCMC) ointment on the rabbit ear hypertrophic scar models. Methods: The optimal formulation of SCMC ointment matrix was screened by the orthogonal designs and a series of evaluation tests. The SCMC ointment was prepared through emulsifying method. The rabbit ear hypertrophic scar models were established and used to investigate the anti-hypertrophic scar effect of SCMC ointment. Results: Our results demonstrated that all the quality control indications of the SCMC ointment met the requirements. Anti-hypertrophic scar activity results showed that all the rabbit ear scar tissues appeared different degrees of shrink and fading, and took an unobvious but palpable shift from hard to soft texture with the low, middle and high concentration SCMC ointments treatments in vivo. Additionally, on 21st day the scar area and thickness in different concentrations of SCMC ointment groups were significantly reduced than control group, in a concentration-dependent manner. The immunohistochemical results also indicated that the SCMC ointment had good anti-hypertrophic scar properties and could inhibit hypertrophic scar formation. Conclusion: The SCMC ointment could improve the blood circulation condition of hypertrophic scar tissues. Our research has demonstrated the Chinese medicine composition ointment with good anti-hypertrophic scar properties that could be used to treat hypertrophic scars. Meanwhile, it provides a theoretical basis for further clinical application.

Computer aided design and three-dimensional printing for apicoectomy guide template / 北京大学学报(医学版)

OBJECTIVE@#To establish an apicoectomy guide template design and manufacturing method, based on multi-source data fusion, computer aided design (CAD) and fused deposition modeling (FDM). The feasibility of the guide template was preliminary evaluated by the in vitro model experiment.@*METHODS@#An extracted upper anterior tooth, after root canal treatment, was optical scanned, after which the extracted upper anterior tooth was poured in an apicoectomy plaster model. Cone-beam computed tomography (CBCT) scanning of the apicoectomy plaster model was performed, after which optical scanning of the plaster model for apical resection surgery was carried out. All of the relevant CBCT and optical scanning data of the extracted upper anterior tooth and the apicoectomy plaster model were introduced into the Geomagic Studio 2012 software. The multi-source data fusion technology was used to virtually simulate the three-dimensional positional relationship of the extracted tooth, the dentition, the alveolar bone and the gingival, based on which, the three-dimensional design of the apicoectomy guide template was completed in the Geomagic Studio 2012 software. With the technology of fused deposition modeling, the apical resection surgical guide template was three-dimensionally printed with the material of polylactic acid (PLA). Under the guidance of the surgical guide template, the root apical resection was performed on the plaster model. After the apicoectomy, the extracted upper anterior tooth was taken off from the apicoectomy plaster model and then was given the optical scanning. The apical resection length and angle were calculated by the function of distance measurement and angle measurement, and the results were compared with the preset values.@*RESULTS@#The length of the apical resection was 2.88 mm along the direction of the long axis of the tooth, which was 0.12 mm lower than the preset 3 mm. The included angle between the apical resection plane and the long axis of the tooth was 77.9°, 12.1° lower than the preset 90°.@*CONCLUSION@#This study successfully established a digital design and production method of apicoectomy guide template by combing the multi-source data fusion, CAD and FDM technology. The design route and the production method are feasible. The study will provide a technology and methodology reference for the development of domestic special software for the digital design of apicoectomy guide template.

Analysis of volatile fatty acids in gingival crevicular fluid of patients with chronic periodontitis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the volatile fatty acids in gingival crevicular fluid (GCF) and to analyze the relationship between the levels of the volatile fatty acids and chronic periodontitis.</p><p><b>METHODS</b>GCF samples taken from 37 patients with chronic periodontitis and 16 volunteers with healthy periodontal status were analyzed by capillary electrophoresis.</p><p><b>RESULTS</b>The detection frequencies and concentrations of succinic acid, butyric acid and valeric acid were significantly higher in GCF of chronic periodontitis than in that of healthy group. The detection frequencies of propionic acid had no statistic difference between the two groups, but the concentrations of it was significantly higher in inflammation group. We also found that the concentrations of succinic acid, propionic acid and butyric acid were significantly lower in shallow pockets than that in deep pockets.</p><p><b>CONCLUSIONS</b>The volatile fatty acids, especially succinic acid, propionic acid, butyric acid and valeric acid were associated significantly with the severity and inflammation of periodontal disease. The levels of succinic acid, propionic acid and butyric acid in GCF were related to pocket depth.</p>

The malocclusion of primary dentition in the suburb of Chengdu: a cross-section survey / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To reveal malocclusion of primary dentition in the suburb of Chengdu.</p><p><b>METHODS</b>Cross-section survey and malocclusion rate calculation were performed.</p><p><b>RESULTS</b>There are 491 children with malocclusion from total 1 279 children; the rate of malocclusion is 38.38%. The most important malocclusion in primary dentition are over bite (III degrees), anterior cross bite, edge to edge bite, early loss of deciduous teeth, fused teeth.</p><p><b>CONCLUSION</b>The rate of malocclusion of primary dentition in the suburb of Chengdu is a little bit light. Much work should be done to prevent or treat the malocclusion of primary dentition.</p>