OBJECTIVETo evaluate the effect of different auxiliary resistance forms on the resistance and marginal fitness of complete crowns for short molar preparations.

METHODSA total of 70 Nissin resin teeth were prepared with 20° total occlusal convergence, 2.5 mm of occlusocervical height, and a shallow finish line on a milling machine. The milled preparations were then randomly assigned to 7 groups of 10. The first group was used as the control group. A total of 30 dies were modified by preparing interproximal grooves with angles of 0°, 6°, and 20° centered on the mesial and distal surfaces of the dies. The rest of the teeth were prepared with occlusal holes in the center of the occlusal surface milled with the same burs to form 0°, 6°, and 20° holes. Cobalt-chromium copings were fabricated for all specimens. The marginal gap of specific points on the axial surface was measured before and after cementation. The resistance of each specimen was evaluated by applying an external force at an angle of 45° to the long axis of the die by using a universal testing machine in a lingual to buccal direction. The maximum force applied before crown dislodgement was measured. Data were analyzed using the SAS 9.2 software.

RESULTSThe results showed that the 0° groove, 0° hole, and 6° hole were effective in improving the resistance of the complete crowns (P<0.05). The 0° groove, 6° groove, 0° hole, 6° hole, and 20° hole had significant difference with the control group in terms of marginal discrepancies (P<0.05).

CONCLUSIONAuxiliary resistance forms with less degree indicate greater resistance force but worse marginal fitness. In clinical practice, if the resistance of a preparation is enough, the auxiliary resistance forms should be avoided from being used.

Cementation ; Crowns ; Dental Prosthesis Design ; Dental Prosthesis Retention ; Humans ; Molar ; Tooth Crown

OBJECTIVETo evaluate the influence of eugenol-containing and resin-containing endodontic sealers on the bond strength of fiber posts using different strategies of root canal irrigation.

METHODSForty-eight mandibular premolars were endodontically treated. The specimens were randomly assigned into two groups according to different endodontic sealers. Group A used Endofil (eugenol-containing endodontic sealer), and group B used AH-plus (resin-containing endodontic sealer). After post space preparation, each group was randomly assigned into three subgroups according to the strategies of root canal irrigation (eight premolars in each subgroup). Group Al and B1: 0.9%NaCl irrigation; Group A2 and B2: 17% ethylene diamine tetraacetic acid (EDTA)+5.25%NaClO+0.9%NaCl irrigation; Group A3 and B3: ultrasonic agitation associated with 1 7%EDTA+5.25%NaClO+0.9%NaCl. One week after the cementation of fiber posts using RelyX™ Unicem, a push-out test was performed to measure the bond strength of the posts. The microstructure of the root canal surface was examined under scanning electron microscope (SEM).

RESULTSThe bond strengths of the six groups were as follows: Al (7.96±2.23) MPa, A2 (9.95±2.89) MPa, A3 (18.88±3.69) MPa, B1 (11.41±3.71) MPa, B2 (14.00±4.04) MPa, and B3 (19.14±3.27) MPa. Statistical analysis revealed a significant interaction between the different endodontic sealers and the strategies of root canal irrigation (P<0.05). Lower bond strength was found in group Al but not in group BI (P<0.05), and the same result was revealed when comparing group A2 and B2. No significant difference was observed between group A3 and B3 (P>0.05). SEM showed that the root canal in group A3 and B3 achieved the cleanest surface with nearly all dentine tubules opened.

CONCLUSIONThe eugenol-containing endodontic sealer can impair the bond strength of fiber posts compared with the resin-containing sealer when the root canal is irrigated by 0.9% NaCl or 17%EDTA+5.25%NaClO+0.9%NaC. No difference was observed between the two sealers when using 17%EDTA+5.25% NaCIO+0.9%NaCl combined with ultrasonic irrigation.

Bicuspid ; Cementation ; Dental Bonding ; Dental Pulp Cavity ; Dental Stress Analysis ; Dentin ; Humans ; Post and Core Technique ; Root Canal Filling Materials ; Root Canal Irrigants ; Root Canal Therapy

A sensitive method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the simultaneous determination of folic acid (FA) and its active metabolite, 5-methyltetrahydrofolic acid (5-M-THF), in human plasma. The analytes were extracted from plasma with methanol solution containing 10 mg/mL of 2-mercaptoethanol and 0.025% (v/v) ammonium hydroxide. FA and 5-M-THF were more stable after the addition of 2-mercaptoethanol and ammonium hydroxide in the sample preparation procedures of this study than they were in the previously published methods. Chromatographic separation was performed on a Hedera ODS-2 column using a gradient elution system of acetonitrile and 1 mM ammonium acetate buffer solution containing 0.6% formic acid as mobile phase. LC-MS/MS was carried out with an ESI ion-source and operated in the multiple reaction monitoring (MRM) mode. The assay was linear over the concentration ranges of 0.249-19.9 ng/mL for FA, and 5.05-50.5 ng/mL for 5-M-THF. The developed LC-MS/MS method offers increased sensitivity for quantification of FA and 5-M-THF in human plasma and was applicable to a pharmacokinetic study of FA and 5-M-THF.

Objective To explore the indication,surgical procedure and the postoperative treatment of breast conserving modified radical mastectomy for early stage breast cancer .Methods The clinical data of 21 patients with early stage breast cancer underwent breast conserving modified radical mastectomy were analyzed retrospectively. Results All patient recovered uneventfully. All the external configuration of the breast were fine. There were no recurrence and no complications in this series. Conclusions The breast conserving modified radical mastectomy is recommended for the early stage breast cancer. The external configuration of breast is fine postoperatively, and patients have higher survival quality.But follow up is necessary in order to find and treat the recurrence of breast cancer.

Objective To construct a stable infectious clone of S191 virus strain used for the pro-duction of live attenuated measles vaccine. Methods Full length cDNA of S191 strain and gene fragments encoding nucleocapsid(N),phosphoprotein(P)and RNA polymerase(L)were synthesis and respectively cloned into the vector pVAX1. The 293T cells were respectively transfected with the recombinant expression plasmids and co-cultured with Vero cells. The supernatants of cell culture were collected for identifying res-cued viruses. The indirect immunofluorescence assay was performed for virus identification. The rescued viruses at different passages in Vero cells and the sequences of the rescued viruses were analyzed. Results Restriction enzyme digestion and sequence analysis showed that the recombinant expression plasmids contai-ning the full length cDNA with an artificially engineered mutation at nucleotide 2101(C-A)and gene frag-ments encoding N,P and L proteins of S191 strain were constructed successfully. The N and P proteins were detected in Vero cells with immunofluorescence assay. A cytopathogenic effect on Vero cells was induced by rescued viruses. Conclusion The stable infectious clones of S191 virus used for the production of live at-tenuated measles vaccine were rescued successfully. An approach by using reverse genetics technique for S191 strain study was established which could be used for the development of new chimeric vaccines against measles virus.

Objective To investigate the CT and MRI findings of granulomatosis with polyangiitis of the nasal cavity and paranasal sinus. Methods The CT and MRI features of eight patients of granulomatosis with polyangiitis in the nasal cavity and paranasal sinus confirmed by histo-pathology were analyzed retrospectively.CT scanning was performed in all eight patients.Routine MRI scanning was performed in seven patients.Dynamic contrast MRI was performed in three cases.SImax ,SIpeak ,Tpeak and MSI of the time-intensity Curves(TICs)were calculated.Results On CT scanning,bilateral middle turbinate,uncinate process and nasal septum were defected in 8 cases.Medial wall of bilateral maxillary sinus showed destruction and other walls of bilateral maxillary sinus showed sclerosis in 8 cases.The ethmoid labyrinth were involved in 6 cases in which the volume of maxillary sinus reduced.The collapse of nasal dorsum and flat nasal bone occured in 4 cases.Nasopharyngeal soft tissue was thicken in 2 cases.Theorbit was involved in 1 case.The mucosal thickness of all group of sinuses were showed in all 8 cases.On MRI scanning,peripheric mucosal of the lesions showed iso or long T1 and long T2 signal in 7 cases.Dynamic-enhanced MRI showed heterogeneous enhancement.TICs showed flat.But in one to four periods showed a slow rising gradient.SIpre was 1 030, SImax 2 500,SIpeak 2 353,Tpeak 100 s,and MSI 1.28%.Conclusion Granulomatosis with polyangiitis of the nasal cavity and paranasal sinus shows some typical CT and MRI features.To summarize the features is helpful to the diagnosis and therapy of the lesion.

The particles suspended in seawater have great influence on pollutant migration and transformation in marine environment, while the lipophilic algae toxins enriched by the particles suspended in seawater will lead more serious toxicity to marine filter feeders. In this study, a new method was developed for the simultaneous determination of eight lipophilic algae toxins in suspended particles by ultra performance liquid chromatography-tandem mass spectrometry ( UPLC-MS/MS ) . After extracted with methanol by ultrasonic-assisted extraction, the sample was separated on an Acquity UPLC BEH C18 column (50 mm×2. 1 mm, 1. 7 μm) using gradient elution of acetonitrile and water containing 5 mmol/L ammonium acetate as eluent modifiers. The qualitative and quantitative analyses were carried out by electrospray ionization ( ESI) tandem mass spectrometry in multiple reaction monitoring ( MRM) mode. Under the optimal conditions, satisfactory precision (relative standard deviations (RSD≤14. 1%), recoveries (83. 8%-110. 4%) and detection limits (2. 9-103 pg/g) of the method were achieved. Good linearity (R2≥0. 99) was also obtained for all studied analytes. Then, the method was applied to determine the amounts of the eight lipophilic marine toxins in authentic suspended particle samples collected from Qingdao near-shore area. Pectenotoxin 2 ( PTX2 ) was detected in the samples from Shilaoren beach and No. 3 bathing beach with concentration ranges of 717 and 790 pg/g, respectively.

BACKGROUND:Occluder implantation in patients with congenital heart disease can increase in vivo platelet adhesion and aggregation, resulting in thrombosis on the occluder surface. OBJECTIVE:To investigate the effect of the occluder on platelet function in patients with congenital heart disease undergoing transcatheter closure. METHODS: Clinical data from 124 patients with congenital heart disease undergoing transcatheter closure were retrospectively analyzed. These patients were divided into groups of atrial septal defect in 46 cases, patent ductus arteriosus in 43 cases and ventricular septal defect in 35 cases according to the types of congenital heart disease. The positive rates for peripheral blood CD62p, CD63 RESULTS AND CONCLUSION:There was no difference in the positive rates of peripheral blood CD and thrombin sensitive protein were compared before and 6 hours, 24 hours, 12 months after occluder implantation. 62p, CD63 and thrombin sensitive protein among three groups prior to occluder implantation. Up to 6 hours after occluder implantation, the expression levels of peripheral blood CD62p, CD63 and thrombin sensitive protein reached peak in the three groups, especialy in the patients with atrial septal defect and ventricular septal defect, then gradualy decreased. After 12 months, the expression levels of CD62p and CD63 recovered in the patients with patent ductus arteriosus and ventricular septal defect, but stil maintained a higher level in those with atrial septal defect (P < 0.05). The expression of thrombin sensitive protein showed no difference among the three groups at different time. These findings indicate that after occluder implantation, the platelet activation is more remarkable and lasts longer in the patients with atrial septal defect and ventricular septal defect, especialy in those with ventricular septal defect.

Objective: To evaluate the efficacy of ultrasound-guided caudal epidural block for postoperative analgesia in the infants undergoing lobectomy under general anesthesia. Methods: Sixty American Society of Anesthesiology physical status Ⅱ or Ⅲ pediatric patients of both sexes, aged 1-3 yr, weighing 10-16 kg, scheduled for elective lobectomy under general anesthesia, were divided into 2 groups (n=30 each) using a random number table method: control group (group C) and epidural block group (group E). Caudal epidural block was performed under ultrasound guidance after induction of general anesthesia and at 15 min before surgery in group E. An epidural catheter was inserted at T_{6, 7} interspace, 0.1% ropivacaine 1 mg/kg was injected at 5 min after injecting 1% lidocaine 3 ml, the diffusion of epidural fluid was controlled at T_3-10, and the epidural catheter was then removed.An analgesia pump was connected at the end of the surgery in two groups.Pain was evaluated using Face Legs Activity Cry Consolability scale.When Face Legs Activity Cry Consolability scale score>3, the pump was pressed.When pain was still unrelieved 5 min later, sufentanil 0.1-0.2 μg/kg was intravenously injected.The patients were followed up for 48 h after operation, and the requirement for additional remifentanil and sufentanil, and the occurrence of postoperative nausea and vomiting, respiratory depression, hypoxemia and over-sedation was recorded.The number of pressing times, extubation time and duration of intensive care unit stay were also recorded.Pain at 1 and 2 days after operation was evaluated using the Postoperative Pain Measure for Parents. Results: Compared with group C, the consumption of remifentanil, the number of pressing times and requirement for additional sufentanil were significantly decreased, the incidence of each index of the Postoperative Pain Masure for Patients was decreased at 1 day after surgery, the extubation time and duration of intensive care unit stay were shortened, and the incidence of nausea and vomiting and over-sedation was decreased in group E (P<0.05). Conclusion Ultrasound-guided caudal epidural block provides better efficacy and fewer side effects for postoperative analgesia in the infants undergoing lobectomy under general anesthesia.

Objective: To explore the risk stratification of pulse oxygen saturation (SpO₂) in patients with emergency hypoxemia patients, and to provide evidence for the identification of critical illness. Methods: Self-designed clinical data registration form for patients with emergency hypoxemia, and prospective collection of 344 hypoxemia patients in the emergency department of Peking Union Medical College Hospital from March to April in 2018, including baseline data (name, gender, age, ID number, date, registration time), hospitalization method, past history, patient complaint and diagnosis, triage level, SpO₂, whether to enter the rescue room, etc. Results: All of 344 emergency hypoxemia patients, there were 163 cases (21.2%) of ambulances, and 107 cases (31.1%) of patients requiring immediate rescue. There were 54 cases (25.7%) and 53 cases (39.6%) in need of immediate rescue in day shift (8:00-20:00) and night shift (20:00-8:00 next day), with 9:00-10:00, 14:00-15:00, 20:00-24:00 in the majority. There was a statistical difference in the way of hospitalization, triage, and SpO₂ (χ²=29.537, 25.780, t=4.722, all P<0.05) . SpO₂ risk stratification was 0.905 in patients without pulmonary disease, and SpO₂ risk stratification in patients with lung disease was 0.765. Conclusions Patients with hypoxemia account for a certain proportion in the emergency department and are in critical condition. The degree of critical condition of patients can be evaluated based on whether they have lung diseases, and the risk stratification of patients can be accurately determined with the help of SpO₂, so as to further guide the hierarchical treatment measures for patients with emergency hypoxemia and rationally optimize the allocation of emergency resources.