Parker M H, Malone K H, Trier A C, Striano T S
Dental Laboratory Branch, Academy of Health Sciences, Ft. Sam Houston, Texas.
J Prosthet Dent. 1991 Dec;66(6):730-3. doi: 10.1016/0022-3913(91)90404-k.
Resistance form of preparations for which castings were made in a large dental laboratory was evaluated. Each preparation was also evaluated for the placement of grooves. Evaluation of resistance form was done by grasping the casting between thumb and index finger and attempting to roll the uncemented casting off the die with finger pressure. Each preparation was tested for resistance form in all directions (buccal, lingual, mesial, and distal), from a fixed point of rotation. Evaluation was by tooth groups: incisors, canines, premolar, and molars. The preparations were found to have resistance form in 96% of the incisors, 92% of the canines, 81% of the premolars and only 46% of the molars. Only nine of 294 preparations evaluated had grooves. Mesial or distal grooves provided resistance to buccal and lingual dislodgment, and buccal or lingual grooves provided resistance to mesial and distal dislodgment.
对在大型牙科实验室制作铸件的预备体的抗力形进行了评估。还对每个预备体的沟的放置情况进行了评估。抗力形的评估是通过用拇指和食指夹住铸件，并试图用手指压力将未粘结的铸件从代型上滚下。从一个固定的旋转点出发，对每个预备体在所有方向（颊侧、舌侧、近中、远中）的抗力形进行测试。按牙组进行评估：切牙、尖牙、前磨牙和磨牙。发现96%的切牙、92%的尖牙、81%的前磨牙和仅46%的磨牙的预备体具有抗力形。在评估的294个预备体中只有9个有沟。近中或远中沟可抵抗颊舌向脱位，颊侧或舌侧沟可抵抗近远中向脱位。
