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By removing a part of the structure, the tooth preparation provides restorative space, bonding surface, and finish line for various restorations on abutment. Preparation technique plays critical role in achieving the optimal result of tooth preparation. With successful application of microscope in endodontics for >30 years, there is a full expectation of microscopic dentistry. However, as relatively little progress has been made in the application of microscopic dentistry in prosthodontics, the following assumptions have been proposed: Is it suitable to choose the tooth preparation technique under the naked eye in the microscopic vision? Is there a more accurate preparation technology intended for the microscope? To obtain long-term stable therapeutic effects, is it much easier to achieve maximum tooth preservation and retinal protection and maintain periodontal tissue and oral function health under microscopic vision? Whether the microscopic prosthodontics is a gimmick or a breakthrough in obtaining an ideal tooth preparation should be resolved in microscopic tooth preparation. This article attempts to illustrate the concept, core elements, and indications of microscopic minimally invasive tooth preparation, physiological basis of dental pulp, periodontium and functions involved in tool preparation, position ergonomics and visual basis for dentists, comparison of tooth preparation by naked eyes and a microscope, and comparison of different designs of microscopic minimally invasive tooth preparation techniques. Furthermore, a clinical protocol for microscopic minimally invasive tooth preparation based on target restorative space guide plate has been put forward and new insights on the quantity and shape of microscopic minimally invasive tooth preparation has been provided.
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Objective To compare the effects of different composite resins as core material on the degree of microleakage in post-core repairation.Methods A total of 46 recently extracted single-rooted mandibular premolars were distributed into different groups according to different core material including ParaCore,AP-X and Ceramage.Then we used direct or indirect forming method to make post-core restorations.All of the specimens were submerged in dyes.Then,they were demineralized,dehydrated and processed to be transparent.The extent of the dye leakage was examined under a stereomicroscope.Results The microleakage value was significantly higher in Group of direct-mold-cement with ParaCore (4.94± 1.71)mm than in Group of indirect-mold-secondary-cement with ParaCore (0.91 ± 0.33) mm,Group of indirect-mold-secondary-cement with AP-X (0.87 ± 0.27) mm,and Group of indirect-mold-secondary-cement with Ceramage (1.02 ± 0.34)mm.Conclusion Different methods of building and cementing FRC post-core restorations,but not different composite resins as core material,have significant effects on the extent of microleakage in post-core repair.
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To compare the microleakage of fiber post and resin-core system fabricated by different methods.The roots of 36 recently extracted single-rooted mandibular premolars were undergone endodontic treatment.Fiber posts and Paracore flowable resin composite were used for fabricating post-core restorations.Microleakage was examined by dye penetration method.The microleakage value was significantly higher in Direct-Mold-Cement-Method group(4.94 ± 1.71) mm compared to Direct-Mold-Secondary-Cement-Method group(0.91 ±0.33) mm and Indirect-Mold-Secondary-Cement-Method group (0.87 ± 0.27) mm (P ＜ 0.05).
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80 extracted human mandible premolars were divided into 10 groups(n =8)based on the post with different tilted angles(0°, buccal 15°and 30°,ligual 15°and 30°).The samples in experiment group were restored with fiber post while in the control group with cast post.Then all the teeth were restored with cast crown and bonded by glass ionomer.Compressive load with the speed of 1.0 mm/min was ap-plied to the restored teeth with a universal material testing machine until failure and the fracture modes were observed.The fracture load of fi-ber post and cast post restoration with the same tilted angles was similar(P >0.05).The main fracture mode of the teeth in all groups was unfavorable tooth fracture.No significant interaction was observed(P =0.217)between the 2 kinds of post and angulation of tilted teeth.
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Objective To evaluate whether S-100β protein could be a serum marker for traumatic spinal cord injury (SCI). Methods From June, 2013 to October, 2014, 24 patients with complete SCI were measured the serum S-100β protein concentrations with en-zyme-linked immunosorbent assay, one week, three and six months after SCI. Serum from ten healthy persons was as normal control. Re-sults The serum S-100βprotein concentrations increased one week and 3 months after SCI (Z>4.273, P<0.001). Conclusion The increase of serum S-100βprotein may help assessing early impairment after complete SCI.
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OBJECTIVE: This study aims to compare the fracture resistance of teeth restored with different post and core systems by cyclic loading test and to predict long-term effects. METHODS: A total of 15 recently extracted mandibular premolars without crowns were endodontically treated. The teeth were randomly divided into three groups with five teeth in each group. Group A, teeth restored with cast metal post and core. Group B, teeth with fiber post and resin core. Group C, teeth with resin filling. All of the teeth were restored with full-cast metal crowns. The specimens were exposed to 300,000 cyclic loadings in a cyclic loading machine and 1,000 thermal cycles between 5 and 55 °C. All of the samples were loaded in AG-IS mechanical testing machine with a compressive load until fracture occurred. The fracture load and the fracture mode of each tooth were recorded. RESULTS: The fracture resistance in group B and C were higher than that of the cast metal post and core restoration (P < 0.05). Repairable fractures were observed in group B and C, whereas unrestorable and catastrophic fractures were found in group A. CONCLUSION: Fiber post and resin filling is a good choice to restore endodontically treated teeth.
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Análise do Estresse Dentário , Técnica para Retentor Intrarradicular , Fraturas dos Dentes , Dente Pré-Molar , Humanos , Dente não VitalRESUMO
This study evaluated the effects of berberine in combination with insulin on early osseointegration of implants in diabetic rats. Fifty male Sprague-Dawley rats were randomly divided into 5 groups: healthy rats were used as control (HC), and streptozotocin-induced diabetic rats were treated with insulin, berberine, berberine + insulin (IB), or no treatment. Each rat received one machined-surface cp-Ti implant into the right tibia and was given insulin injection and/or gavage feeding with berberine daily for 8 weeks until being sacrificed. Serum levels of alkaline phosphatase (ALP) and bone gamma-carboxyglutamic acid-containing protein (BGP) were analyzed in each group. Peri-implant mineral apposition was marked by fluorochrome double-labeling and osseointegration was histomorphologically examined. The ALP and BGP levels decreased in diabetic rats but were successfully corrected by insulin and berberine combined treatment. Moreover, untreated diabetic rats had less labeled mineral apposition and impaired osseointegration. In contrast, Groups I, B, and IB were observed with increased peri-implant bone formation. The combination treatment of insulin and berberine was more effective than each administrated as a monotherapy. These results suggest that berberine combined with insulin could promote osseointegration in diabetic rats, thereby highlighting its potential application to patients, though further studies are needed.
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Objective To evaluate DTI for early diagnosis and prognosis of diffuse axonal injury (DAI)in the moderate and sever traumatic brain injury (sTBI).Methods 30 patients with sTBI and 30 healthy controls were studied with T1 WI and DTI.The frac-tional anisotropy(FA)and ADC were quantified from different regions of interest(ROI)including the genu of corpus callosum(gCC), the trunk of CC,the splenium of CC(sCC)and the integrity CC.The FA and ADC of the same R0I was compared between TBI group and control group,and FA and ADC of the different parts of CC were compared in TBI group.Correlations between the FA or ADC and coma duration of the TBI patients were analyzed by Pearson linear correlation.Results Compared with control group,the FA value decreased significantly in each ROI,while ADC was reversed.The FA or ADC of the different ROI were correlated with co-ma duration in TBI group.Conclusion DTI is sensitive to detect the white matter injury of TBI.FA value detected in the CC can help diagnose DAI earlier and evaluate the degree of injury.
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Various functional proteins are differently expressed in each pathologic stage after spinal cord injury, representing injury and the pathological change of repair. Ideal biomarker is helpful to evaluate complicated biological reactions of spinal cord injury and predict prognosis. As specific serum markers of central nerve injury, neuron-specific enolase (NSE) and astrocyte primary calcium binding protein S-100βhad been studied preliminarily, but the specificity and sensitivity need more research. Future efforts still need to develop ideal bio-markers to predict functional outcome.
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@#Various functional proteins are differently expressed in each pathologic stage after spinal cord injury, representing injury and the pathological change of repair. Ideal biomarker is helpful to evaluate complicated biological reactions of spinal cord injury and predict prognosis. As specific serum markers of central nerve injury, neuron-specific enolase (NSE) and astrocyte primary calcium binding protein S-100β had been studied preliminarily, but the specificity and sensitivity need more research. Future efforts still need to develop ideal biomarkers to predict functional outcome.
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<p><b>OBJECTIVE</b>This study aims to compare the fracture resistance of teeth restored with different post and core systems by cyclic loading test and to predict long-term effects.</p><p><b>METHODS</b>A total of 15 recently extracted mandibular premolars without crowns were endodontically treated. The teeth were randomly divided into three groups with five teeth in each group. Group A, teeth restored with cast metal post and core. Group B, teeth with fiber post and resin core. Group C, teeth with resin filling. All of the teeth were restored with full-cast metal crowns. The specimens were exposed to 300,000 cyclic loadings in a cyclic loading machine and 1,000 thermal cycles between 5 and 55 °C. All of the samples were loaded in AG-IS mechanical testing machine with a compressive load until fracture occurred. The fracture load and the fracture mode of each tooth were recorded.</p><p><b>RESULTS</b>The fracture resistance in group B and C were higher than that of the cast metal post and core restoration (P < 0.05). Repairable fractures were observed in group B and C, whereas unrestorable and catastrophic fractures were found in group A.</p><p><b>CONCLUSION</b>Fiber post and resin filling is a good choice to restore endodontically treated teeth.</p>
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Humanos , Dente Pré-Molar , Análise do Estresse Dentário , Técnica para Retentor Intrarradicular , Fraturas dos Dentes , Dente não VitalRESUMO
The aim of the study was to investigate the biocompatibility and osteogenic effectiveness of the porous nanohydroxyapatite/polyamide 66 (n-HA/PA66) scaffold material that was cultured with the rat bone marrow mesenchymal stem cells (rBMSCs), under the static culture condition and the dynamic perfusion culture condition in vitro, and to investigate whether the 3D perfusion culture condition was better in provoking proliferation of rBMSCs than the 3D static culture condition. The Methyl thiazolyl tetrazolium (MTT) assay, alkaline phosphatase (ALP) activity assay, Osteocalcin (OCN) assay and scanning electron microscope (SEM) were used to observe the proliferation and differentiation of rBMSCs. The samples were respectively harvested at 1st, 3rd, 7th, 14th, and 21st days and effect comparisons were made between the two of the culture conditions. The results showed that values of MTT, ALP, and OCN were increased continuously and revealed a significant difference between the two culture conditions (p < 0.05). On the 14th day, SEM revealed calcified nodules 2-8 µm in diameter in the lamellar structure. Under the static culture condition, the pores were covered with the cells looking like a piece of blanket, but under the perfusion culture condition the cells were observed to have a 3D lamellar structure. In conclusion, the porous n-HA/PA66 scaffold material can be used as a good candidate material for the bone scaffold construction in the tissue engineering because of its excellent 3D structure, which can greatly improve the proliferation and differentiation of rBMSCs and make them proliferate and osteogenesis even better under the perfusion culture condition.
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Reatores Biológicos , Células-Tronco Mesenquimais/citologia , Fosfatase Alcalina/metabolismo , Animais , Materiais Biocompatíveis/química , Técnicas de Cultura de Células , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Durapatita/química , Desenho de Equipamento , Teste de Materiais , Células-Tronco Mesenquimais/metabolismo , Microscopia Eletrônica de Varredura , Nanoestruturas/química , Nylons/química , Osteocalcina/metabolismo , Osteogênese , Perfusão , Ratos , Engenharia Tecidual , Alicerces TeciduaisRESUMO
Microbial colonization on implanted devices and biofilm formation is a recurrent complication in implant surgery and may result in loss of implants. The aim of this study was to deposit silver nanoparticles on a titanium surface to obtain antibacterial properties. In the present study, we prepared a silver nanoparticle-modified titanium (Ti-nAg) surface using silanization method. The morphology and chemical components of the Ti-nAg surface were characterized by scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS). Two species of bacteria, Staphylococcus aureus and Escherichia coli, were utilized to test the antibacterial effect of the Ti-nAg treated surface. The SEM examination revealed that a small quantity of silver nanoparticles was sparsely deposited on the titanium surface. The diameter of these nanoparticles ranged from ten to several hundred nm. EDS analyses revealed that there was 4.26% of Ag present on the surface. After a 24-hour incubation, 94% of Staphylococcus aureus and over 95% of Escherichia coli had been killed on the Ti-nAg surface, and the SEM examination of anti-adhesive efficacy test showed that there were less bacteria attached to Ti-nAg surface than to a control surface of untreated Titanium. These data suggest that silver nanoparticle-modified titanium is a promising material with an antibacterial property that may be used as an implantable biomaterial.
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Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Nanopartículas/administração & dosagem , Nanopartículas/química , Prata/química , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Titânio/química , Antibacterianos/química , Antibacterianos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Nanopartículas/ultraestrutura , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
The objective of the research is to investigate the elements of routine sandblast technique on the evolution of bending strength of dental infiltrated Al2O3 ceramics and the underlying erosion mechanism. The plane specimens of an infiltrated ceramic were manufactured, polished and then tested under the modified pen-like sandblasting apparatus (90 degrees erosive angle and 10 mm sandblasting distance), with different grit sizes, working pressure and disposing time. Half of samples were selected randomly and sintered subsequently with Vitadur alpha veneering porcelain. Before and after sintering, the three-point-bending strengths was measured, and the surfaces of dental porcelain were observed with SEM and LCSM. The bending strength of ceramics decreased significantly after sandblast as compared with that of empty control group. After the procedure of sintering the veneering porcelain, the descending evolution of bending strength slowed down. Under the present manufacturing conditions, grit size effect is prominent among those correlative elements of sand grit size, working pressure and disposing time. And fatigue cracking characterizes the mechanism of erosion of dental infiltrated Al2O3 ceramics.
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Humanos , Óxido de Alumínio , Química , Materiais Dentários , Química , Análise do Estresse Dentário , Teste de Materiais , Ligas Metalo-Cerâmicas , Química , Resistência ao Cisalhamento , Estresse MecânicoRESUMO
<p><b>OBJECTIVE</b>The purpose of this study was to introduce cryotreat technique into prosthetic dentistry by investigating the wear resistance changes of SDA-II medium melting-point castable alloy before and after cryotreat.</p><p><b>METHODS</b>15 samples were divided into three groups, i.e. control group, cryotreat group, cryotreated plus post-cryogenic treat group. Weight loss measurement was used to examine the wear resistance.</p><p><b>RESULTS</b>For SDA-II medium melting-point castable alloy, cryotreat effectively improved its wearing resistance; so far as the wear resistance was concerned, the post-cryogenic treatment was unnecessary.</p><p><b>CONCLUSION</b>The results obtained above suggest that cryotreat was an effective method in enhancing the wear resistance of SDA-II medium melting-point castable alloy.</p>
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Humanos , Temperatura Baixa , Ligas Dentárias , Análise do Estresse Dentário , Dureza , Teste de Materiais , Estresse Mecânico , Propriedades de SuperfícieRESUMO
<p><b>OBJECTIVE</b>Today metal-ceramic restorations are widely accepted in dental practice because of their good aesthetic and biocompatible properties, but there are still several problems to be resolved, among which the influences of their margins on gingival health is noticeable. The purpose of this study was to investigate the influences of metal-ceramic restoration margin on gingival health.</p><p><b>METHODS</b>129 abutments of metal-ceramic restorations, including their margins' fitness, location and smoothness were examined and their influences on gingival health were analyzed.</p><p><b>RESULTS</b>There was a close relation between the metal-ceramic restorations' margins and the gingival health.</p><p><b>CONCLUSION</b>In order to maintain the gingival health, the margins should be smooth, closely fitted, no overhanging and in a moderate location (i.e. not below the gingival more than 1 mm).</p>
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Feminino , Humanos , Masculino , Doenças da Gengiva , Gengivite , Hemorragia , Ligas Metalo-CerâmicasRESUMO
<p><b>OBJECTIVE</b>The purpose of this study was to investigate effects of cryotreat on the corrosion resistance of SDA-II medium melting-point castable alloy.</p><p><b>METHODS</b>12 samples were divided into three groups, including the control group, the cryotreated group and the cryotreated & post-cryogenic treated group. The cryotreating process was firstly dropping the temperature from room temperature to -170 degrees C with dropping rate 3 degrees C/min, maintaining -170 degrees C for 2 hrs, and then returning to ambient temperature with an increasing rate of 1 degree C/min. The post-cryogenic process was maintaining the samples in 300 degrees C for 1 hr. Finally, all samples were subjected to the electrochemical potentiodynamic polarization after immersed in the artificial saliva (ISO/TR 10271: 1993 (E), pH 6.8) for 24 hrs at ambient temperature. The exposing area of each sample was 10 mm x 10 mm. The electrochemical tests were carried out in the artificial saliva under 37 degrees C, with the scanning rate of 20 mV/min, starting potential -200 mV below OCP and stopping current 10(-3) A. The corrosion currents (Icorr), the pitting corrosion potentials (Eb) and the potentiodynamic polarization curves were observed using the 283 electrochemical corrosion measuring system automatically.</p><p><b>RESULTS</b>For SDA-II medium melting-point castable alloy, cryotreat reduced corrosion rate of the alloy, but had no effect on the pitting corrosion potential. As far as the post-cryogenic treatment, it didn't affect the corrosion resistance.</p><p><b>CONCLUSION</b>The results suggested that cryotreat was an effective procedure in enhancing the corrosion resistance of SDA-II medium melting-point castable alloy, and it may be applicable in prosthetic dentistry.</p>
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Humanos , Temperatura Baixa , Corrosão , Ligas Dentárias , Técnica de Fundição Odontológica , Dureza , Teste de Materiais , Mecânica , Saliva Artificial , TemperaturaRESUMO
Objective:To investigate the feasibility of improving the corrosion resistance of nickel-chromium alloys by the means of cryogenic treatment. Methods:16 disk samples were divided into 4 groups, including control group(C), cryotreat group(E1),tempering after cryotreat group(E2) and simulative porcelain sintering after cryotreat group(E3). All samples were subjected to electrochemical potentiodynamic polarization after immersed in the artificial saliva ISO/TR 10271:1993(E) pH 6.8 for 24 h at ambient temperature. The metallography of all groups were observed by SEM. Results:①Cryogenic treatment elevated the pitting corrosion potential and dropped the corrosion current of Ni-Cr alloys. Following simulative porcelain sintering,as well as tempering after cryotreat, decreased the corrosion current. But the corrosion potential of Ni-Cr alloys fell after cryotreat and following simulative porcelain sintering. Tempering after cryotreat did not affect the pitting corrosion potential. ②Much small secondary substance separated out and evenly distributed along the crystals of Ni-Cr alloys after cryotreat. Conclusion:Cryogenic treatment effectively improves the electrochemical corrosion resistance of Ni-Cr alloys, and tempering following cryotreat is unnecessary. It is not recommended to sintering porcelain after cryogenic treatment.
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To study the effects of high salt intake together with cold stress on rat cardiac renin angiotensin aldosterone system (RAAS) in rats. Male Wistar rats were randomly divided into four groups: control, high salt (8%NaCl), cold stress (5 2℃) and compound group (8%NaCl+cold stress). Blood pressure and body weight were measured once a week. The experiment ran for 8 weeks. Renin activity (RA), angiotensinⅡ (AngⅡ), and aldosterone (Aldo) in plasma and left ventricle were determined with radioimmunoassay. Angiotensin II receptor mRNA was determined with RT PCR. The results showed that ①Rats in compound group had higher blood pressure than rats in the other three groups ( P
