The purposes of this study were to observe the cavity wall morphology and to evaluate the degree of cavity cleanliness when root-end retrograde cavity preparation was done with ultrasonic diamond instruments.
To observe the morphology of retrocavity and to evaluate the degree of cavity cleanliness, root-end resections were done on 20 palatal roots of extracted maxillary first molars after canal filling with gutta-percha. Retrocavities were prepared using either ultrasonic diamond instruments or stainless steel ones of medium power setting of level 6 (Miniendo^(TM), EIE, CA, U.S.A.). Morphology of the cavity, degrees of the remaining canal debris and smear layer were evaluated under the scanning electron microscope.
The results were as follows :
Cavities prepared with ultrasonic diamond instruments showed scratched appearance of wall, while ultrasonic stainless steel preparation showed hatcheted appearance.
Ultrasonic diamond instruments induced more smear layer than stainless steel ones did (p<0.01) in the cavity. However, there was no significant difference in canal debris (p>0.05).
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