• 作者： 張心涪
• 作者服務機構： 國立臺灣大學醫學院牙醫學系
• 中文摘要： 本文係研究三種四環塑膠圈鏈經由不同程度之瞬間伸張後，在既定時間（1，4，24小時和1，2，3週）內觀察其力量衰退變化情形。結果顯示：（1）未經瞬間伸張之圈鏈，在測試三星期中有大部份力量失去情形。大部份力量之失去在最初幾個小時發生，爾後力量衰退情形減低。（2）圈鏈經瞬間伸張之長度愈大，伸張後剩餘之力量愈小。（3）塑膠圈鏈經適當瞬間伸張後，可有效地減少圈鏈初期使用時過強的力量。 圈鏈經瞬間伸張至與測試距離相同或比測試距離稍長一些時，可以減少初期使用時過強之力量，然而仍維持與控制組（未經瞬間拉長）相同之力量。如果瞬間伸張長度比測試距離長很多時，與控制組比較，此伸張不但可減少初期使用時過強之力量，並且在測試之三星期中，其力量亦減少。
• 英文摘要： The object of this study was to investigate the effect of instantaneous prestretching on the forcedegradation behavior of three kinds of four-link plastic modules. A simple sliding apparatus was used toprestretch instantaneously the plastic modules to 100, 200 and 300% of their original length. After pre-stretching, specimens were tested at 20, 25 and 30 mm stretch distances. Force measurements were per-formed at the following occasions: before prestretching; at the end of prestretching; after 1,4 and 24 hours;and after 1, 2 and 3 weeks. The following conclusions can be drawn from this investigation: (1)The con-trol specimens which had not been instantaneously prestretched exhibited considerable force loss over thethree-week test period. Most of the force loss occurred rapidly during the first few hours, with a muchlower subsequent force degradation rate. (2) Instantaneous prestretching to a greater length resulted in alower force value remaining at the end of prestretching. (3) Instantaneous prestretching of the plastic mo-dules is an efficient method to dissipate the high initial force level which is clinically undesirable. Prestretching of the modules around or slightly longer than the stretch distance could reduce thehigh initial force level and still maintain the same force level as the control groups. However, if the lengthof instantaneous prestretching of the four-link plastic module was much longer than the testing stretchdistance which corresponds to the average distance from the first molar to the canine in the same quadrant,the prestretching would reduce both the high initial force value and the force value during the three-weektest period, as compared with the control group.
• 中文關鍵字： instantaneous prestretching; orthodontic plastic modules; force degradation
• 英文關鍵字： --