本研究之目的在探討根管修形與不同充填方式對根尖封閉性之影響。本實驗使用68顆單根管的牙齒，將牙齒隨機分做四組（A至D組）。所有組別皆以退展法修形。A組和B組修形為.10 mm/mm之錐度，C組和D組修形為.05 mm/mm之錐度。A組和C組以側方充填法充填，B組和D組以Thermafil充填。將牙齒浸泡在墨汁中48小時後將其脫鈣、脫水並浸泡於冬青油中使其透明，以實體顯微鏡紀錄其結果。將結果使用統計軟體加以分析。結果顯示在根尖滲漏方面，A組及B組之根尖滲漏較D組輕微。分析顯示根管修形為顯著之影響因素（P<0.05），而充填方式則否（P=0.348）。由以上結果得到結論：較大的根管修形錐度在使用Thermafil充填的情況下可改善根管充填之根尖滲漏之現象。側方充填法與Thermafil充填法之充填效果在根尖滲漏滲漏方面沒有差異。

The purpose of this study was to investigate the sealing ability in relation to root fillings made by lateral compaction of gutta percha and by the use of Thermafil obturators with different canal tapers prepared by step-back technique. Sixty-eight extracted permanent human teeth with single canal were randomly divided into four groups (A to D). All of the groups were instrumented using a step-back technique. Groups A and B were instrumented making the taper .10 mm/mm, while groups C and D were instrumented making the taper .05 mm/mm. Groups A and C were obturated with lateral compaction technique, while Groups B and D were obturated
with Thermafil obturation technique. The teeth were immersed in India ink for 48 h and then decalcified. Methyl salicylate was used to render the teeth transparent. Apical leakage was measured under stereo microscope. The data were analyzed with statistical analysis software.
Apical leakage of groups A and B were less than group D. The effect test showed that shaping of the canal was a significant factor (P<0.05) but obturation technique was not significant (P=0.348).
Canals shaped with greater taper using step-back technique resulted in less apical leakage, which were obturated with Thermafil. There was no difference in apical leakage between cold lateral compaction technique and Thermafil technique.