To study the effects of different post design on retention. 27 simulated tooth roots made of PMMA were divided into three groups, then manufactured the cement-expanded composite screw post-core system (CECSP), cement screw post-core system (CSP) and cast metal post-core system (CMP). The root and post-core system was tensiled by the speed of 10 mm/min on the Instron 4302 and recorded the retention force. It appeared significantly different between retention force of CECSP and CSP and CAM (P < 0.05). As a result, the retention mechanical properties of CECSP was much better than those of cement screw post-core system and cast metal post-core system. Therefore, it is possible to find a new way for restoration of endodontically treated teeth.
Acrylic Resins ; Cementation ; Composite Resins ; Crowns ; Dental Materials ; chemistry ; Dental Prosthesis Retention ; Dental Stress Analysis ; Humans ; Polyurethanes ; Post and Core Technique ; Tensile Strength

Objective To investigate the application value of metronidazole combined with cefuroxime sodium in the laparoscopic treatment of patients with acute non-simple appendicitis.Methods The subjects were 80 patients with acute non-simple appendicitis who underwent laparoscopic appendectomy from July 2020 to June 2023.Among them,41 patients with acute non-simple appendicitis who were treated with metronidazole combined with cefuroxime sodium for laparoscopic surgery were used as the observation group,and 39 patients with acute non-simple appendicitis who were treated with metronidazole combined with ceftriaxone sodium for laparoscopic surgery were used as the control group.The intraoperative situation,inflammation control before and after surgery,postoperative recovery status,and adverse reactions after medication were compared between the two groups.Results There were no statistically significant difference between the two groups in terms of periappendiceal abscess/peritonitis,surgical time,and intraoperative bleeding,the differences were not statistically significant(P>0.05);The inflammatory indexes of acute non-simple appendicitis in both groups gradually returned to normal after surgery,and the white blood cell count,procalcitonin(PCT)and C-reaction protein(CRP)levels in the observation group showed greater decrease than those in the control group,the differences were statistically significant(P<0.05)on the first day and the third day after surgery.The duration of analgesics use and hospital stay in the observation group were(1.8±1.2)and(3.5±0.7)d,respectively,which were significantly shorter than those of(2.7±1.4)and(4.6±0.4)d,the differences were statistically significant(P<0.05).The incidence of intra-abdominal infection in the observation group was 7.7%,which was significantly lower than that of 24.4%in the control group,the difference was statistically significant(P<0.05).The adverse reactions in the two groups were 4.9%and 7.7%,respectively,and the difference was not significant(P>0.05).Conclusion Metronidazole combined with cefuroxime sodium combined with laparoscopic appendectomy can significantly reduce the incidence of abdominal infection in patients with acute non-simple appendicitis,it has high safety.