Suboptimal debridement quality produced by the single-file F2 ProTaper technique in oval-shaped canals.

Introduction: The aim of this study was to determine whether the debridement quality of the single-file F2 ProTaper instrumentation technique is comparable to a full conventional ProTaper sequence in both round and oval-shaped root canals.

Methods: Fifty-four recently extracted vital lower incisors were instrumented with either a full range of ProTaper Universal instruments in rotary motion (group 1) or with the single-file F2 ProTaper technique in reciprocating motion (group 2). Teeth were previously classified as round or oval-shaped by means of bidirectional radiographs, resulting in 24 round canals, 24 oval canals, and 12 controls. After instrumentation, the roots were demineralized, and the apical 3 mm was multi-sliced and processed for histologic examination. The percentage of residual pulp tissue (PRPT) was calculated with the aid of image analysis software. Univariate analysis of variance was used to verify the variables influencing PRPT.

Results: Both canal shape and technique significantly influenced PRPT (P < .05). Oval-shaped canals displayed much more PRPT than round canals in both techniques (P < .05). The difference in PRPT between the techniques depended on the root canal shape, since a significant interaction between canal shape and technique was observed (P < .05). Group 1 displayed considerably less PRPT in oval canals than group 2 (P < .05), whereas in round canals no significant difference was found between the 2 techniques (P > .05).

Conclusions: The single-file F2 ProTaper technique displayed similar PRPT to the full range of ProTaper instruments in round canals. However, the debridement quality of the single-file F2 ProTaper technique was suboptimal in oval canals.