An ultrastructural study of debris retention by endodontic reamers

The aim of this study was to determine the structure and the ultrastructure of the organo-mineral coating retained by endodontic reamers. Premolars extracted for orthodontic reasons were instrumented using Rispi Micromega reamers mounted on a counterangle Giromatic. One group of premolars was instrumented without irrigation, a second group was instrumented with irrigation using physiological saline, and a third group was instrumented with irrigation using Dakin. After instrumentation, the specimens were observed by scanning electron microscopy. Two microscopic techniques were used for each specimen. Secondary electron imaging was used to examine the amount of material adhering to the surfaces of the Rispi reamers after instrumentation, whereas backscattered electron imaging was used to determine the variation in the organo-mineral composition of the smear layer adhering to the reamers. The deeper layer adhering to the surface of the reamers was predominantly organic in nature no matter which instrumentation or irrigation technique was used.