A COMPARATIVE STUDY ON THE APICAL LEAKAGE OF RETROFILLING AFTER APICAL CAVITY PREPARATION WITH ULTRASONIC INSTRUMENT

초음파 기구에 의한 치근단 와동형성후 역충전의 밀폐성에 대한 연구

This study was conducted to evaluate and compare the apical leakage in the following retrofilling techniques after apical resection; No apical cavity preparation and no retrofilling(control group), Amalgam(group I) or silver glass ionomer cement(group II) retrofilling after apical cavity preparation with mini contra-angle and bur, Amalgam(group III) or silver glass ionomer cement(group N) retrofilling after apical cavity preparation with ultrasonic micro endo tip. Extracted ninety upper anterior and lower canine teeth were fixed in skull simulators and root canals were prepared with step-back method and obturated with gutta-percha and zinc oxide eugenol sealer. Obturated roots were resected 2mm from apical ends and apical cavities of 1mm width and 2mm depth were prepared and retrofilled by above mentioned methods. After application of nail varnish on all surface except resected surface, apical 1/3 of the roots were placed in 1% methylene blue solution for 3 days. After longutudinal sectioning to expose central parts of filled materials, depths of penetrated dye were measured by measuring microscope and were analyzed statistically. The results were as follows. 1. Having no relation with instruments used in apical cavity preparation, amalgam retrofilling groups(group I and II) showed less apical leakage which was not significant statistically than no retrofilling group(control group) (P<0.05), but silver glass ionomer cement retrofilling gruoups(group II and IV) showed significantly less apical leakage than no retrofilling group(control group) (P<0.01). 2. In the groups retrofilled with the same material, the apical leakage in cavities prepared with ultrasonic micro endo tip (group III and IV) was less than that in cavities prepared with mini contra-angle and bur(group I and II), but not significant statistically(P>0.05). 3. When apical cavities were prepared with same instrument. the egroups retrofilled with silver glass ionomer cement(group II and IV) showed significantly less apical leakage than the groups retrofilled with amalgam(group I and III)(<0.01).