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BACKGROUND:It is convenient to fabricate porcelain veeners using chairside computer aided design/computer aided manufacture (CAD/CAM) system. However, the color of the restorations is not ideal when the veener is cemented immediately, so different surface treatments are needed. OBJECTIVE:To investigate the influence of different surface treatments on the color of chairside porcelain veneers made of CEREC Blocs and the color match between the porcelain veneers and teeth. METHODS:Five fresh extracted maxillary central incisors were selected and prepared. Twenty-five 0.6 mm porcelain veneer specimens were fabricated with Sirona CEREC Blocs by chairside CAD/CAM system, and then randomized into five groups. Untreated specimens served as control group. The other four groups were treated respectively by polishing, glazing, glazing after polishing or staining. The color parameters of specimens and the teeth were measured with ShadeEye NCC on the middle 1/3 region of labial surfaces, and color differences (ΔE) between the specimens and teeth were calculated. Data were analyzed by SPSS 19.0 software. RESULTS AND CONCLUSION:Compared with the control group, the L* value of the glazing, glazing after polishing and staining groups were significantly decreased (P0.05). Compared with the control group, the ΔE values of glazing, glazing after polishing and staining groups were significantly decreased (P0.05). These results suggest that the chairside porcelain veneers made of CEREC Blocs can obtain satisfactory aesthetic appearance by glazing and staining.
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How to cultivate oral medical graduate students with solid general medical founda-tion is still under exploration. There are some systematic, comprehensive and relatively weak limita-tions for different departments' rotations in training general clinical skills for professional degree post-graduates in stomatology. With the establishment of a comprehensive teacher group of oral medicine, prosthodontics and oral & maxillofacial surgery in department of general dentistry, students can be trained for general clinical thinking and skills, and the students' ability of general clinical practice has been strengthened via these programs. On the basis of postgraduate students' analysis of structures and learning interests and under the premise of upholding the uniform requirements, the individualized and hierarchical teaching has been conducted to the students, paying attention to stimulating their interest in learning. Besides, by way of a comprehensive assessment, students' academic performance has been objectively evaluated.
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ObjectiveTo summarize the research and manufacturing ideas of precise positioning instrument and its feasibility and safety in the minimally invasive percutaneous nephrolithotripsy.Methods The precise positioning instrument was preliminarily made by integrating ruler with protractor.Fifty cases of kidney stones or upper ureteral stones were recruited in the study.There were 32 males and 18 females with mean age of 47 years (21 -75 years).Of them,6 cases had open surgery history and 31 cases had different degrees of hydronephrosis.The distance from the mid-point of renal pelvis to the plane of the dorsal surface and the distance from the incident point of the mid-point of pelvis on the dorsal surface to spinous process were measured by ruler on the preoperative CT images.According to the measured results,the point,angle,direction and depth of needle were calculated by geometric formula,and then fix position puncture and percutaneous puncture channel expansion were completed by precise positioning instrument and calibrated by Carm X-ray machine.ResultsThe puncture channels were established successfully in all of the 50 cases.Forty-six cases were punctured successfully by just one try,and the success rate of one puncture only was 92.0％.C-arm was used in none of the cases during the channel establishing process.Each patient was Xrayed 1 -3 times,and the average was 1.4 times.Targeting deflection or renal pelvis injury occurred in none of these cases.ConclusionThe application of the homemade precise positioning instrument is a safe and quick method for the establishment of puncture channel during percutaneous nephrolithotripsy,meanwhile the surgeons can reduce the exposure to radiation.
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<p><b>OBJECTIVE</b>To investigate the stress distributions under load in an all-ceramic crown of the upper central incisor in differential thickness.</p><p><b>METHODS</b>The 3-dimensional finite element model of all-ceramic crown of the upper central incisor in differential thickness was applied with differential loads (100, 150, 200 N). The stress values and distributions of all-ceramic crown were calculated and expressed.</p><p><b>RESULTS</b>The tendency of stress distributions in all-ceramic crown of differential thickness and loads was similar. The maximal stress intensity value was located in the loading site and the cervical region. As the thickness of all-ceramic crown increased, the stress concentration reduced. When the load increased, the stress values increased, especially in the loading site and the cervical region.</p><p><b>CONCLUSION</b>The increasing of the thickness of all-ceramic crown will decrease stress concentration. Because stress concentration is mainly in cervical region and loading site, these regions should be cared in fabrication of all-ceramic crown.</p>
Subject(s)
Humans , Ceramics , Crowns , Dental Porcelain , Dental Stress Analysis , Finite Element Analysis , Incisor , Tensile StrengthABSTRACT
Aim To prepare a new oral colon-specific delivery formulation and to investigate the release profile in vitro and the colon-specific delivery property in vivo in dogs. Methods Sodium 4-aminosalicylic acid was selected as the model drug. The combination of Eudragit RL30D and RS30D were used as sustained-release film, and Eudragit FS30D used as enteric film, which was expected to release drug depending on pH and time. The release profile of tablets was studied in three phosphate buffers with the pH 6.5, 7.0 or 7.4 for 12 h after a simulated gastric presoak for 2 h in 0.1 mol · L-1 HCl. The tablets were radiolabelled with 99mTc to make their release times and positions in the gastrointestinal tract be followed using a gamma camera. Results For the in vitro study, there was no drug released in 0. 1 mol ·L- 1 HCl for 2 h, and release occurred slowly when pH was above 6.5. Drug was released faster while pH was higher. For the in vivo study, the coated tablets remained intact in the upper gastrointestinal tract, and drug release began after the colonic arrival. The uncoated tablets, however, disintegrated in the stomach of the dogs rapidly. Conclusion The coating could protect the drug until the tablets reached the ascending colon, where drug was released slowly for over 10 h.
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Objective:To establish a precise three-dimensional finite element model of temporomandibular joint.Methods: On the basis of images of Chinese Visible Human, the reverse engineering technology was applied to reconstruct the Computer Aided Design(CAD) model of temporomandibular joint.Afterwards, the model was established. Results:A three-dimensional finite element model consisting of 66 122 nodes and 212 704 elements of temporomandibular joint including cortical bone, cancellous bone, mandibular dental arch, masticatory muscles, articular cartilage and periodontal ligament was constructed. Conclusion:The finite element model is more efficient and more precise.
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AIM: To prepare Yuanhuzhitong Dispersible Tablet.(Rhizoma corydalis,Radix Angeliae Dahuricae) METHODS: To inspect formula and preparation technology of dispersible tablet using monofactor experiment and U_9(9~4) uniform design experiment on the basis of multi-markers. RESULTS: The weight of dispersible tablet was definited as 400 mg,the pharmaceutical adjuvants were 34% starch,40% MCC and 10% lactose as filler,8% cCMC-Na as disintegrat,15% PVPK_(30) alcohol water blend as adhesive on the basis of mono-factor test.(CONCLUSION): The formula is reasonable and technology is feasible.