Assessment of coronoid process trajectories during the mandibular kinematics - an ex vivo study.

OBJECTIVE: This study investigated the trajectories of the different morphologic variants of the coronoid process in relation to the zygomatic bone, from closed mouth to maximal mouth opening, in an ex vivo model. STUDY DESIGN: CBCT volume of a dry human skull articulated with the mandible was acquired, and the mandible was segmented. Ten different morphologies of the right coronoid processes were designed in relation to the zygoma and numbered. The coronoid processes and the segmented mandible were 3D-printed. These coronoid processes could be fitted and separated from the mandible as a puzzle piece. The human skull was occluded with the 3D-printed mandible, and CBCT volumes were acquired for six different standardized positions for each right coronoid process, and the entire process was repeated three times. RESULTS: A total of 156 CBCT volumes, comprising three repeated sets of 52 volumes each, were acquired and assessed. All the sets of CBCT measurements showed good to excellent agreement. A 50 mm mouth opening could be achieved for coronoid processes 1-8. With the coronoid process 9, the maximal mouth opening was 20 mm, and with the coronoid process 10, no mouth opening was accomplished. CONCLUSION: Morphological forms of the CPs 1-8 encountered unobstructed mouth opening, with only CP 9 demonstrated a 20 mm maximal mouth opening, and CP 10 was incapable of any mouth opening.