Changes in diameter, cross-sectional area, and extent of canal-wall touching on using 3 instrumentation techniques in long-oval canals

Objective. The objective of this study was to compare the shaping ability of manual H-files, rotary nickel-titanium ProTaper system, and reciprocating SafeSiders in long oval-shaped root canals. Study design. The roots of 45 human premolars were sectioned at 2 levels in the middle third and reassembled using a 3-piece metal mold. Pre- and postinstrumentation cross-sectional images were superimposed and evaluated in terms of change in buccolingual-to-mesiodistal canal ratio, maximum buccolingual and mesiodistal canal dimensions, and cross-sectional areas. Ratios of touched canal wall and canal outline with more than 200 mu m dentin removal to the original canal perimeter were also calculated. Results. The buccolingual-to-mesiodistal ratio decreased after instrumentation with no difference among techniques (P > .05). The change in the buccolingual dimension was significantly less for SafeSiders compared with H-files and ProTaper (P < .05). The change in mesiodistal dimension was significantly less with SafeSiders compared with H-files only (P < .05). The change in area, in descending order, was as follows: H-files > ProTaper > SafeSiders (P < .05). The ratio of touched canal outline was highest with H-files, compared with ProTaper and SafeSiders (P < .05), and H-files recorded the highest ratio of canal outline with more than 200 mu m of dentin thickness removal (P < .05). Conclusions. None of the 3 instrumentation techniques completely prepared the oval root canal. Manual and rotary NiTi instrumentation may perform better than reciprocating SafeSider instrumentation in shaping oval canals. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:688-695)