Hu Xiao-ping, Hu Piao-ping, Zhu Hong-shui
Dept. of Prosthodontics, The Affiliated Stomatological Hospital of Nanchang University, Nanchang 330006, China.
Hua Xi Kou Qiang Yi Xue Za Zhi. 2009 Aug;27(4):422-4, 429.
To study the retentive force and deformation of acetal resin clasp.
40 premolars and 40 molars were cast respectively. Undercut of 0.25 mm or 0.50 mm depth were measured for each with undercut gage. According to the type of abutment and the depth of undercut, the specimens were divided into 4 groups: Premolars with 0.25 mm undercut, premolars with 0.50 mm undercut, molars with 0.25 mm undercut and molars with 0.50 mm undercut, 20 specimens each group. 10 three-arm clasps with resin and Co-Cr alloy were fabricated in each group, respectively. The clasps were set into the corresponding abutments and soaked in distilled water. The retentive force of the clasps when 0, 720, 1440, 2160, 2880, 3600, 4320 consecutive times of setting in and removing out from the abutments were measured. The distance between the tips of retentive arm and resistant arm after 0 and 4320 cycles were recorded.
The retentive force and deformation of the resin clasp are significantly lower than those of Co-Cr clasp.
研究乙缩醛树脂卡环的固位力及变形情况。
分别铸造40颗前磨牙和40颗磨牙。用倒凹测量仪测量每颗牙0.25mm或0.50mm深度的倒凹。根据基牙类型和倒凹深度，将标本分为4组：0.25mm倒凹的前磨牙、0.50mm倒凹的前磨牙、0.25mm倒凹的磨牙和0.50mm倒凹的磨牙，每组20个标本。每组分别制作10个树脂和钴铬合金的三臂卡环。将卡环安装到相应的基牙上并浸泡在蒸馏水中。测量卡环在连续0、720、1440、2160、2880、3600、4320次进出基牙时的固位力。记录0次和4320次循环后固位臂和抗力臂尖端之间的距离。
1）树脂卡环的平均固位力（1.69N）显著低于钴铬卡环（5.87N）（P<0.01）。在相同因素下，树脂卡环的固位力显著小于钴铬卡环（P<0.01）。磨牙卡环的固位力显著低于前磨牙模型（P<0.01）。0.25mm倒凹卡环的固位力显著低于0.50mm倒凹卡环（P<0.01）。随着循环次数的增加，钴铬卡环的固位力显著降低（P<0.01），但树脂卡环的固位力无显著变化（P>0.05）。2）4320次后，钴铬卡环固位臂和抗力臂尖端之间的距离显著增加（P<0.05），但树脂卡环尖端之间的距离无显著变化（P>0.05）。
树脂卡环的固位力和变形显著低于钴铬卡环。
