[A comparative study on preparation techniques for fine curved canal of posterior teeth]

A comparison of canal shape produced by routine preparation technique,ultrasonic technique and step-back technique for fine curved canal of posterior teeth was done in this article.The result showed that the canal shape prepared with step-back technique was better,for its postoperative angle change and apical transportation were less than the other two groups.On the contrary,the canal shape prepared with routine technique was worst.Therefore it was concluded that the step-back technique was the first choice for preparing the fine curved canal of posterior teeth.Routine technique was not suitable to prepare the fine curved canal of posterior teeth.