Objective : To compare the stress distribution of residual posterior root restored with a new titanium alloy post of different diameter and taper, and discuss the rational design of posterior tooth post by the three-dimensional finite element method. Methods : Mandibular second premolar image data was obtained by CBCT, and the mandibular second premolar post models with different diameter and taper were established with the help of Mimics data conversion, Geomagic Studio image processing technology and Creo/Parametric software. Then Abaqus was used to simulate the load condition of prosthesis and analyze the Von Mises stress of the cervical and apical regions. Results: With the same diameter, the influence of the different post tapers on the peak stress of the root cervical area was irregular. When the taper was the same, the peak stress of the root apex area decreased firstly and then increased as the diameter increased. When the diameter was 1 mm, the peak stress of the root cervical and apex area was the lowest. Conclusion The effect of diameter on the stress distribution of dentin is more important than that of taper. To select the reasonable diameter and taper of the post is helpful to reduce the peak stress of the root cervical and apex area.

Objective Visual electrophysiology and optical correlation tomography angiography(OCTA)were used to investigate differences in preoperative retinal function in patients with type 2 diabetic cataract(DC)without obvious retinopathy(NDR)and to determine the clinical application of whole-process blood glucose man-agement(WBGM)for improving postoperative vision in DC patients.Methods This study investigated the preop-erative and postoperative visual electrophysiology(N75,P100,photopic FERG,and scotopic FERG),peripapil-lary retinal nerve fiber layer(pRNFL)and peripapillary capillary vessel density(ppVD)data,as well as trends in these data changes during blood glucose management intervention.Results As the course of T2DM progressed,FBG and HbA1c increased,the N75 and P100 lategraduancy periods of patients gradually lengthened,and the photopic FERG,scotopic FERG,pRNFL,and ppVD values decreased at each postoperative time point.At the same time,the best corrected visual acuity(BCVA)of patients after surgery gradually decreased(P<0.05).Compared with that at 1 week after surgery,the BCVA of Group A(without whole-process blood glucose manage-ment)gradually increased at 1 month and 3 months after surgery but showed a downward trend at 1 year after sur-gery.The BCVA of Group B(with whole-process blood glucose management)gradually stabilized at 1 month after surgery,and at all time points after surgery,the BCVA of Group B was better than that of Group A.The results showed that N75 and P100 in Group A were greater than those in Group B,while the photopic and scotopic FERG,pRNFL,and ppVD(%)in Group A were lower than those in Group B.In addition,N75 and P100 in Group A showed a gradual prolongation trend at various time points after surgery,while photopic FERG,scotopic FERG,pRNFL,and ppVD(%)showed a gradually decreasing trend.However,the above data in Group B gradu-ally stabilized at 3 months after DC surgery,approaching the preoperative level of the group(P<0.05).In the state of whole blood glucose management,although N75 and P100 both reached their longest durations at 1 week af-ter surgery,N75,P100,photopic FERG,scotopic FERG,and pRNFL showed a gradually decreasing trend at 1 month and 3 months after surgery,while ppVD(%)gradually increased(P<0.05).At various time points from 3 months to 1 year after surgery,the overall trend of the above indicators remained stable and close to the preoperative values(P>0.05).Conclusion According to the results of the quantitative analysis of visual electrophysiology and OCTA,in DC patients without obvious retinopathy and with the worsening of diabetes,retinal function decreased,but whole-process blood glucose management effectively restored retinal function and improved visual quality after surgery.