A Three-Dimensional Finite Element Analysis of the Stress Distribution Around the Bone Mini-Implant Interface Based on the Mini-Implant Angle of Insertion, Diameter, and Length.

Background: Temporary anchorage devices or mini implants have gained great attraction due to their capability to provide absolute anchorage, low cost, versatility, and can be loaded immediately after placement. Material and Methods: Finite element analysis was used to evaluate the distribution of stress at the bone mini implant interface based on different angles of insertion (30°, 45°, 60°, and 90°) mini implant diameter (1.3 mm, 1.6 mm, and 2 mm) and mini implant length (6 mm, 8 mm, and 10 mm). A retraction force of 2 N was applied. Results: Areas of maximum stress concentration were the head and neck of the mini implant and cortical bone around the mini implant. A very minimal amount of stress was found in the cancellous bone. The maximum stress found in the cortical bone was 5.1301 MPa and in the mini implant was 26.355 MPa with an angle of insertion of 30°, a 1.3 mm diameter, and a 6 mm length. The minimum stress found in the cortical bone was 1.4702 MPa and that in the mini implant was 5.3895 MPa with an angle of insertion of 90°, a 2 mm diameter, and a 10 mm length. Conclusion: For maximum stability, mini implants should be placed at a perpendicular angle of insertion with sufficient diameter and length.

A Cross-sectional Study to Evaluate Nuclear Changes in Buccal Mucosa Following Panoramic Radiography.

AIM AND OBJECTIVE: To evaluate the possible genotoxic effect of X-rays on buccal mucosa while exposing to dental panoramic radiography using micronucleus test. MATERIALS AND METHODS: The study group comprised of 30 healthy subjects, 15 males and 15 females, aged between 24 years and 65 years. Samples were obtained from the exfoliated oral mucosa cells of buccal mucosa before and 12 days after exposing the patients to panoramic radiography. RESULTS: The study reported that there was no significant increase in the number of micronuclei cells present before and after panoramic radiography. Positive correlation existed between age with pre- and postexposure micronuclei. CONCLUSION: Diagnostic dental panoramic radiograph does not induce micronuclei in the target buccal epithelium cells. A positive correlation between age and micronuclei frequency was established. CLINICAL SIGNIFICANCE: Panoramic radiographs does not induce cytotoxicity but increase frequency may be vulnerable to genotoxic effects in buccal mucosal cells. Hence, dental radiographs should be prescribed only when necessary.