Objective To investigate the influence factor of cavity filling complicating odontoclasis and evaluate the prevention measure. Method We collected 82 posterior teeth complicating odontoclasis which cavity filling was diagnosed by own hospital and analysed factors related to odontoclasis. Results After cavity filling 0 to more than 3 years

the odontoclasis ratio is 9.76 %

12.20 %

30.49 % and 47.56 % respectively; the odontoclasis ratio of complex cavity is 68.29 % and that of simple cavity is 31.71 %; the odontoclasis ratio of nonvital pulp teeth is 76.83 % and that of vital pulp teeth is 23.17 %. These differences have statistical signifficanc. Tongue （palatal） tip odontoclasis is more than buccal tip. Conclusion Cavity filling time

faulty cavity and nonvital pulp are important causes of odontoclasis. The odontoclasis of posterior teeth can be prevented by avoiding dysfunctional bite and using proper methods of treatment of endodontics.