Cause analysis of root fracture in anterior teeth with post crown and its design improvement

Objective: To explore the relations between root canal design, post crown type and root fracture after postcrown restoration. Method: Discuss the methods of preventing root fracture by cause analysis of root fracture frommechanical aspect in post crown restored anterior tooth. Results: Positions of the prepared root canal oriface and postcrown types are connected with root fracture. Conclusion: It is useful to prevent root fracture by choosing proper postcrown type, designing proper position and apperance of root canal oriface. It is suggested that root canal oriface properlyinclined to none pin hole at which side are beneficial to root fracture prenention.