Computer aided design of bio-mechanical mandible

Objectives: To make a computer aided design(CAD) for titanium mandibular prosthesis (Bio-Mechanical Mandible,BMM) upon biomechanical principle of mandible. Methods: The three dimensional finite element model (3-DFEM) of mandible was established depending on CT image of a normal occlusion adult from east China released as DICOM file. According to biomechanical laws of mandible, hemi-mandibular prosthesis, including fixations, was designed applying CAD technique. To analyse the stress distribution in prosthesis under four loading conditions, such as ipslateral loading, contralateral loading, bilateral loading and oblique loading. SAS 6.12 was used in T test and variance analysis for statistical study. Results: BMM consisted of buttress structures and hollow-out structures, double abutments with lag screws along biomechanical tract of mandible was designed for BMM fixation. Under four loading conditions, the stress of BMM was reasonable and well distributed, where the maximum stress was located to the angle area of mandible. There was no statistical difference in stress distribution between fixation units(F=1.42, p=0.2997>0.05).The cancellous bone surrounding inferior abutment of BMM underwent the maximum stress over other fixation units. However, there existed no statistical difference in maximum stress distribution of the cancellous bone surrounding inferior abutment of BMM against the normal (T=-0.0849, p=0.9377>0.05). Conclusions: The design of Bio-Mechanical Mandible (BMM) upon CAD technique was reasonable, which conform the biomechanical principle of mandible.