砄bjective: To establish two dimensional infinite model for endodontic endosseous implants in order to set up infinite element method and study the stress distribution of the apical foramen area of endodontic endosseous implant. Methods: Based on the analysis of two dimensional endodontic endosseous implants model with finite element method, left and right areas beside the apical foramen were selected as infinite domains including implant dentin and ligament sections. D N interactive method was used to connect the finite and infinite domains. Results: After ten times interaction between finite and infinite domains with D N interactive method, the outcome approached to a stable numerical value close to the displacement of both domains. Conclusion: The infinite model of two dimensional endodontic endosseous implants established by D N interactive method is efficient and accurate.

Objective: To study the precise stress distribution in the apical foramen area of endodontic endosseous implant. Methods:After analysis of the two-dimensional endodontic endosseous implants model with finite element method, left and right areas beside the apical foramen were selected as infinite domains for calculation. Results:Under 45? axial right oblique loading, the stress concentration occurred in both infinite domains of the apical foramen. The tension stress concentrated in the infinite domain near the load side,but the other side was compress concentrated. Two stress concentration points were just at the central points, which were intersections between implant and dentin. In the implant and dentin section, the stress reduced in all directions from two stress concentration points, but in the ligament section, the result was contrary. Conclusion:It is helpful to keep the root stable when the fulcrum of the root changed to lower part after restoration. In the implant area,the diameter of implant at the apical foramen of root shouldn't be reduced for the protection of root in clinical work;It is very important to preserve the tissue of periodental ligament for endodontic endosseous implants.

OBJECTIVETo study the precise stress distribution of the apical foramen area of endodontic endosseous implant, in order to improve the prosthetics of endodontic endosseous implant.

METHODSAfter analysis of the two-dimensional endodontic endosseous implants model with finite element method, left and right areas beside the apical foramen were selected as infinite domains to calculate. D-N interactive method was used to connect the finite and infinite domains.

RESULTSUnder 45 degrees axial right oblique loading, the stress concentration occurred in both infinite domains of the apical foramen. The infinite domain nearing the load side was tension stress concentration, but the other side was compressive stress concentration. Two stress concentration points were just at the central points, which were intersections between implant and dentin. The stress reduced in all directions from these two stress concentration points, but in the ligament, the result was contrary.

CONCLUSIONSThe change of the tooth rotational center is helpful to the tooth stability and carrying capacity after restoration. In the implant area, the diameter of implant at the apical foramen of root shall not be reduced to protect root in clinical work. It is very important to preserve the tissue of periodontal ligament for endodontic endosseous implants.

Dental Implantation, Endosseous ; Dental Models ; Dental Stress Analysis ; methods ; Humans

Objective:To investigate the relationship of glycated hemoglobin(HbA1c)and brain natriuretic peptide(BNP)levels with clinical prognosis of acute myocardial infarction.Methods:A total of 108 patients with acute myocardial infarction combined with diabetes mellitus, who underwent percutaneous coronary intervention(PCI)from March 2016 to June 2017 in our hospital, were enrolled.According to the HbA1c level, patients were divided into three groups: Group A(HbA1c≤6.9%, n=36), Group B(7%≤HbA1c≤7.9%, n=31)and Group C(HbA1c≥8%, n=41). HbA1c and NT-proBNP levels, cardiac function classification at admission and discharge, the incidence of adverse cardiac events during hospitalization and left ventricular ejection fraction(LVEF)at admission, discharge and 3 months after discharge were analyzed.Results:Among the three groups, plasma NT-proBNP levels were higher in Group C than in Group B and Group A( P<0.05), and there was no significant difference between Group B and Group C( P<0.05). Furthermore, HbA1c levels were positively correlated with NT-proBNP levels in Group C( P<0.05). Cardiac function grading was better in Group A and Group B than in Group C at discharge.During hospitalization, the incidence of adverse cardiac events in Group C was 29.3%, which was higher than in Group A(8.3%)and Group B(9.7%)( P<0.05). LVEF levels were significantly improved in Group A and Group B at discharge and 3 months after discharge, compared with those at admission, while Group C had no significant improvement in LVEF levels and had lower LVEF than Group A and Group B( P<0.05). Conclusions:HbA1c and NT proBNP levels can be used as a joint monitoring indicator in patients with acute myocardial infarctions after PCI, to help prevent and reduce the incidence of complications and mortality in patients with acute myocardial infarction after PCI and improve clinical prognosis.