The paper describes an inexact tree-matching algorithm to register non-isomorphic 3D coronary artery trees over time. This work is carried out in the frame of the determination of the optimal viewing angles on the C-arm acquisition system for coronary percutaneous procedure. The matching method is based on association graph and maximum clique. Different similarity measures are compared, which use tree characteristics and geometric features of vascular branches. In order to take into account the topology variation between 3D vascular trees and thus improve the performance of the algorithm, we propose to insert artificial nodes in the association graph. Results show that unmatched node rate significantly decreases with the insertion of artificial nodes.