Finite element analysis and experimental evaluation on stress distribution and sensitivity of dental implants to assess optimum length and thread pitch

BACKGROUND AND OBJECTIVE

The dental implant is one of the long term proper remedies to recover a missed tooth as a different prosthetic rehabilitation way. The finite element (FE) method and photoelasticity test are employed to achieve stress distribution and sensitivity in dental implants in order to obtain optimum length and thread pitch.

METHODS

The finite element method and experimental test are developed to evaluate stress distribution and sensitivity around dental implants. Three dimensional FE models of implant-abutment, cortical bone and cancellous bone are created by considering a variation of 0.6 to -1 mm on threads pitch while the implant lengths range from 8.5 mm to 13 mm. Then, axial and oblique forces are applied to the models to obtain the resultant stress contours.

RESULTS

The results indicate that the resultant von Mises stresses in the implant-abutment, cortical bones, and cancellous bones are different. The optimized setting for length and pitch is suggested according to maximum von Mises stress and sensitivity analysis.

CONCLUSIONS

It is concluded that the present FE model accurately predicts stress distribution pattern in dental implants. The results indicate that sensitivity of length play a more significant role in comparison with thread pitch. The accuracy of FEM results in comparison with those of the photoelasticity test recommends applying computation methods in medical practice as great potential in terms of future studies.

The Effectiveness of Prenatal Intervention on Pain and Anxiety during the Process of Childbirth-Northern Iran: Clinical Trial Study

BACKGROUND

Due to the painful nature of childbirth and its maternal and neonatal complications, the woman needs support in this phase of their life. Increased knowledge and skills during pregnancy prepares pregnant mothers for labor and leads to promoted health.

AIM

This study was designed to evaluate the effectiveness of "prenatal education" on the process of childbirth.

SUBJECTS AND METHODS

This clinical trial was conducted on 195 pregnant women, that is, control group (N = 132) and case group (N = 63) attending health centers in Amol-Iran from 20 weeks of gestation age during 2012. Case group members attended in "prenatal education" class and the control group only received routine care. Data were collected through demographic questionnaire, standard hospital anxiety questionnaire, and a checklist related to childbirth information, and intensity of pain based on visual analogue scale and McGill scales. The data were analyzed by Statistical Package for the Social Sciences software using t-test and Chi-square test.

RESULTS

The result of this study showed that the parent with a high level of education was more interested to participant in prenatal classes. The anxiety level in case group (who received education) was 14.47 (4.69) and in control group it was 16 (4.86), (P < 0.001) the pain intensity in case group was 85.68 (1.85) and in control group was 90.99 (14.72) (P = 0.03), intervention on labor such episiotomy was 39 %66.1 (39/63) in case group and 80 %72.8 (80/132) in control group (P = 0.01) and cesarean section was 13 %17.1 (13/63) in case group and 58 %32.2 (58/132) in control group (P = 0.01).

CONCLUSIONS

According to findings of this study, the prenatal education and psychological support are beneficial for mothers during pregnancy and labor. Therefore, it is recommended for educating all the pregnant women.