Stochastic Multi-Scale Finite Element Analysis of the Drilling Force of Trabecular Bone during Oral Implant Surgery

To avoid procedural accidents during/after oral implant surgery in a jawbone (e.g., perforation of the lingual side due to an inadequate drilling angle or scratching the mandibular canal), it is important for dentists to develop skilled drilling techniques. We have developed a stochastic multi-scale prediction of apparent elastic moduli of the jawbone with modified first-order perturbation-based stochastic homogenization in which individual differences of drilling properties relating to bone quality can be evaluated with a force-sensitive device. To establish drilling properties in various types of jawbone and the perforation case, and for drill diameters, we propose an original computational method that avoids procedural accidents by defining the drilling angle as a parameter and quantifying individual differences and the inner distribution of bone quality in several jawbones as a drilling force. Three samples demonstrated that drilling forces changed depending on the trabecular structure, with the drilling force changing little around the mandibular canal and increasing just before perforation. Drilling force also depended on the drill diameter but did not always match its size. Estimated drilling forces of the expected value and 50% and 90% probability results suggested prominent differences in drilling properties. This information enables dentists to develop a skillful surgical technique.