No abstract

Incorporating glass fiber in composite restorations may alter the stress state within the structure depending on fiber position.

Background. The choice between reducing the bone height and inserting a shorter implant with a greater diameter or a longer and narrower implant without altering the bone height is a challenge in clinical practice. Objectives. The purpose of this finite element analysis (FEA) was to compare the pattern and level of stress around implants with different lengths and diameters and with different amounts of bone loss, which changes the implant-crown ratio over time, depending on the available bone and the treatment modality. Material and methods. The FEA was carried out to evaluate the stress distribution in bone around 3.25 × 13 mm and 4 × 11 mm 3i implants, and 3.3 × 12 mm and 4.1 × 10 mm Straumann ® implants. A 3D segment of the mandible was reconstructed from a computed tomography image of the posterior mandible. Occlusal force was simulated by applying 200 N vertical and 40 N horizontal loads to the occlusal node at the center of the abutment. The pattern of stress distribution in bone was evaluated in 10 models for each implant, representing 0-9 mm of bone resorption. Results. The results showed that along with decreasing the implant insertion depth, and consequently the implant-crown ratio, the amount of stress in bone increased. The amount of stress increased with an increase in depth of bone loss in all models, but there was no significant change in the amount of stress in the first several millimeters of bone loss. Conclusions. The results suggest that in terms of stress distribution, it is better to reduce the bone height and insert shorter implants with a greater diameter than longer implants with a smaller diameter.