1.Three-dimensional finite element analysis of angled abutments in anterior maxilla implant restoration
Liangzhi DU ; Zhe XU ; Ping SHI ; Juan CHAI ; Xiaofeng CHANG
Journal of Xi'an Jiaotong University(Medical Sciences) 2016;37(3):403-407
Objective To explore the effects of angled abutments on the anterior maxilla implant restoration. Methods We analyzed the biomechanical properties of implants of different sizes (Φ3.5 mm,4.0 mm and 4.5 mm in diameter;L11.5 mm and L13 mm in length)after connecting different angled abutments (0°,10°,20°,and 30°) using finite element method.Results The stresses and strains of loading parts of restorations increased and their distribution became more concentrated as the angle of abutment increased.Cortical bone of Φ3 .5 implants with smaller angle (10°or less)andΦ4.0 implants with abutments had the risk of overpassing the bone elastic threshold when the angle approached 30°.However,the cortical bone elastic deformation was within a safe range at all angles inΦ4.5 group.Conclusion We should consider the diameter of the implant when selecting angled abutments.The angled abutments are not suitable for small diameter implants.The bite force should be under control when needed. The larger angled abutments can be applied in the standard and major diameter implants and it is necessary to avoid occlusal overloading.
2.The effects of angled abutments with small diameter implant restoration in anterior maxilla:A finite ele-ment analysis
Liangzhi DU ; Zhe XU ; Ping SHI ; Xiaofeng CHANG
Journal of Practical Stomatology 2016;32(4):526-531
Objective:To study the influences of angled abutments connected with small diameter implants in anterior maxilla restora-tion.Methods:Simulation models of angled abutment with small diameter restoration in anterior maxilla were established,the biome-chanical properties of the models were studied by finite element method(FEM)analysis.Results:Following the increase of the abut-ment angle,the stress and strain of all parts increased linearly and more concentrated,while appropriate prosthetic crown could share some load.Cortical bone elastic deformation exceeded the threshold when the abutment angle was bigger than 8 °.Conclusion:With abutment angle increase,stresses and strains will increase and will be more concentrated,which is unfavorable for load conduction.Ap-propriate crown can reduce the adverse effects of angled abutment.Angled abutment should not be used for d 3.5 implant.
3.Effects of artificial bone particles in maxillary sinus augmentation in rabbits:An experimental study
Xiaofeng CHANG ; Liangzhi DU ; Shaoli LIU ; Juan CHAI ; Longlong HE
Journal of Practical Stomatology 1995;0(04):-
Objective: To compare JGW with autogenous bone when used as grafting material in maxillary sinus floor augmentation.Methods: A study was conducted by performing a bilateral maxillary sinus floor augmentation with autogenous bone and JGW(Jin Gu Wei,Golden Bone,bone substitute,Shanghai Xiaobo Tec.) on rabbits.The process of bone formation was evaluated during different periods by imageology and histomorphology methods.Results: At 2nd week the gray scale of JGW was very lower than that of autogenous bone,but no significant difference was found at 12th week.The number of osteoblasts decreased with the time,no significant difference was found at 12th week.The degradation of JGW was relatively faster.Conclusion: JGW is feasible in maxillary sinus floor augmentation.
4.A clinical study of piezosurgery osteotomy in lateral sinus floor augmentation
Liangzhi DU ; Hainan FENG ; Xiaofeng CHANG ; Xiaohong LI ; Shaoli LIU
Journal of Practical Stomatology 2014;(5):689-692
Objective:To evaluate the clinical effect and safety of piezoelectric osteotomy in lateral sinus floor augmentation.Meth-ods:53 implants were placed in 30 sites after lateral sinus floor augmentation(LSFA)in 29 patients by piezoelectric osteotomy.47 implants were placed simultaneously with LSFA,6 were delayed.6-8 months after implantation,the final fixed prostheses were per-formed.The patients were followed-up at 3,6,and 12th months after restoration.Results:The mean residual bone height(RBH) was 4.46 mm before operation.The mean height of sinus elevation was 7.34 mm after operation.No membrane perforation occurred. Peri-implantitis,peri-implant mucositis and implant mobility were not found during follow-up.X-ray examination showed good os-seointegration in the interface between the implants and bones.The implant survival rate and the operation success rate were 100%. Conclusion:The application of piezosurgery is safe and reliable in lateral sinus floor augmentation.
5.Urodynamic analysis of recent bladder function following radical hysterectomy
Xianjing CHEN ; Yiyi SONG ; Pengming SUN ; Chaoqin LIN ; Liangzhi CAI ; Kaihong DU
Tumor 2010;(3):243-246
Objective:To study the variation of recent bladder function of the patients who received radical hysterectomy and evaluate its significance. Methods:Sixty-three patients with cervical carcinoma in International Federation of Gynecology and Obstetrics(FIGO) stage IB1 to ⅡA received urodynamic examination before and after operation. The urodynamic parameters included filling cystometry, pressure-flow rate, and electromyography of sphinctienter. Results:Radical hysterectomy induced significant increase in the first sensation (P<0.01)and post voiding residual of bladder (P<0.01) ;whereas caused significant decrease in the maximum volume(P<0.01), compliance(P<0.01),maximum flow rate(P<0.01) and the pressure at the maximum flow rate(P<0.01), respectively, compared with the corresponding values before the operation. Short-term bladder dysfunctions were observed in 34 patients (54.0%) including bladder detrusor dysfunction, low compliance bladder, bladder outlet obstruction, dyssynergia of urethral external sphincter and detrusor overactivity. The incidences of low compliance bladder and bladder detrusor dysfunction increased significantly after operation (P<0.01). Urinary retention was found in 28.6%(18/63) patients. The incidences of bladder detrusor dysfunction (66.7% vs 20.0%) and detrusor overactivity (33.3% vs 4.4%) in the group with urinary retention were significantly higher than those of corresponding group without urinary retention. Conclusion:The bladder function had obvious short-term changes following radical hysterectomy. In the many types of bladder dysfunction the main dysfunctions were low compliance bladder and bladder detrusor dysfunction. The bladder detrusor dysfunction might be the major cause of the urinary retention following the surgery. Urodynamic test was important for post-operative analysis and treatment of bladder dysfunction.
6.The evaluation of peri-implant bone defects with bioelectrical impedance in canine
Longxun ZHOU ; Zhaoli MENG ; Fangfang LIU ; Longlong HE ; Liangzhi DU ; Yong ZHANG ; Xi-aofeng CHANG
Journal of Practical Stomatology 2015;(1):77-80
Objective:To measure the bioelectrical impedance around the dental implants with bone defects.Methods:Bilateral maxillar second premolar were extracted in 6 native mongrel dogs,implants were placed immediately with or without bone defect of corresponding alveolar bene.Impedance value(IV)between the implant and contralateral mouth corner was measured by LCR TEST-ER.IVs were compared and analyzed by SPSS.Results:IVs of bone defect group were bigger than that of control group(P <0.05), in largger defect group were smaller than that in smaller group(P <0.05).Conclusion:Bioelectrical impedance can be used as an evaluation of peri-implant bone defects and the size of bone defect.
7.Influence of urodynamic factors on urinary retention in patients with cervical carcinoma after radical hysterectomy
Xianjing CHEN ; Yiyi SONG ; Liangzhi CAI ; Kaihong DU ; Chaoqin LIN ; Yanzhao SU ; Jin YU
Chinese Journal of Obstetrics and Gynecology 2010;45(9):677-681
Objective To study the effect of urodynamic factors on the urinary retention of the patients with cervical cancer received radical hysterectomy. Methods Seventy-two patients with cervical cancer Ininternational Federation of Gynecology and Obstetrics (FIGO) stage Ⅰ bl to Ⅱ a hospitalized in Fujian Provincial Maternity and Child Health Hospital between June 2006 and August 2009, who were not found any abnormal representation of urodynamics before the operation, were divided into the group with urinary retention and the group without urinary retention based on whether urinary retention after the operation. All patients were detected by urodynamic examination following radical hysterectomy. Data obtained from urodynamic examination were analysed by logistic regression to evaluate the influence of urodynamic factors on the urinary retention postoperation. Results Twenty-one patients out of all were found with urinary retention after the operation , the incidence rate of urinary retention was 29%. The first sensation after operation in both groups were increased significantly than those before operation[ ( 171 ±61 )ml vs.(126 ±28)ml, (134±39)ml vs. (119 ± 17)ml,all P<0.05], while the maximum volume[ (337 ±66) and (300 ±66)ml, respectively], the compliance[ (31 ±25) and (29 ± 18) ml/cm H2O (1 cm H2O =0. 098 kPa), respectively], the maximum flow rate[ (10 ±4) and (12 ±5) ml/s, respectively] and the pressure at the maximum flow rate [ (27 ±9) and (32 ±8) cm H2O, respectively] were decreased obviously after radical hysterectomy in both the group with urinary retention and the group without urinary retention ( all P <0.05), compared with the corresponding value before the operation. The urodynamic changes in urinary retention group was much more severe than those in group without urinary retention ( P < 0. 05 ). The single factor analysis results showed that bladder destusor dysfunction ( OR = 8. 20, 95% CI: 2.62 - 25. 66, P <0. 01 ) and lack of sensation ( OR = 6. 90, 95% CI: 1.95 - 24. 43, P < 0. 01 ) were relevant to the urinary retention post-operation. While there were not relationship was found between low compliance bladder( OR =1.99, 95% CI:0. 70 - 5.63, P = 0. 195 ), detrusor overactivity ( OR = 2. 51, 95% CI: 0. 73 - 8.67, P =0. 144), bladder outlet obstruction ( OR = 3.77, 95% CI: 0. 76 - 18. 57, P = 0. 104 ) or dyssynergia of urethral external sphincter( OR =2. 67, 95% CI:0. 49- 14. 45, P =0. 255 ) and urinary retention following the operation. There were an antagonistic effects ( OR = 7.60, 95% CI: 1.43 - 40. 39, P = 0. 017 ) of detrusor overactivity and bladder destrusor dysfunction on urinary retention. The multiple factors analysis results revealed that bladder destusor dysfunction( OR = 7.01, P < 0. 01 ) and lack of sensation( OR = 5.45, P =0. 018)were the independent risk factors influening on the urinary retention post-operation. Conclusions There are obvious urodynamic change in cervical cancer patients following radical hysterectomy. Bladder destrusor dysfunction and lack of sensation are the independent urodynamic risk factors influencing on urinary retention following radical hysterectomy, while detrusor over activity may be a protective effect on bladder destrusor dysfunction post-operation in some degree. Urodynamic test is important for analysis and treatment of urinary retention following radical hysterectomy.
8.The effect of diameter of the screw-access hole on the implant prosthodontic system and surrounding cortical bone-A 3D finite element analysis
Zhe LI ; Bowen QIN ; Xiaofeng CHANG ; Zhaoli MENG ; Feng PAN ; Miao WANG ; Liangzhi DU
Journal of Practical Stomatology 2018;34(2):182-187
Objective: To investigate the stress and stress distribution generated on each component of implant prosthodontic system and surrounding cortical bone when different diameters of screw-access hole (SAH) were prepared on molar crown. Methods: A fimite element(FE) model of partial mandible without first molar was set up, and an Bego implant was insert into it. A total of 5 models of the crown were computer-simulated by varying the diameter (Φ = 0-4 mm) of the SAH. The loading forces were 200 N axially (0°) and 100 N obliquely (45°) respectively on occlusive surface. The FE analysis was performed by computer. Results: Φ ≤3 mm: stress on occlusal surface of crown was almost unchanged and mainly distributed in the loading area. Φ = 4 mm, stress appeared an obvious rise and reached the maximum, the stress concentration under vertical load was changed to the hole margin. In vertical loading, screw could remain at a relatively low stress level when diameter did not exceed 1 mm. No changes on other components was observed. Conclusion: SAH diameter of 1 mm is recommended when a cement-and screw-retained crown is used in posterior region.
9.Discovery of a normal-tension glaucoma-suspect rhesus macaque with craniocerebral injury: Hints of elevated translaminar cribrosa pressure difference.
Jian WU ; Qi ZHANG ; Xu JIA ; Yingting ZHU ; Zhidong LI ; Shu TU ; Ling ZHAO ; Yifan DU ; Wei LIU ; Jiaoyan REN ; Liangzhi XU ; Hanxiang YU ; Fagao LUO ; Wenru SU ; Ningli WANG ; Yehong ZHUO
Chinese Medical Journal 2024;137(4):484-486