Methods: Thirty complete crown wax patterns made with a brass die were divided randomly into 5 groups(a,b,c,d,e).

• 方法:用铜制全冠代型模具制作30个全冠蜡型,随机分成a、b、c、d和e共5组,e组作为对照组,用TitavestCB包埋材料一次性包埋。