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 μm 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 μm 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.
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 μm 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 μm 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.