ABSTRACT
The aim of the present study was to evaluate the influence of spreader shape on the quality of obturation. Forty-five single canal teeth with varying degrees of apical curvature were used throughout. The canals were prepared using the step-back technique and obturated with lateral condensation. The teeth were classified into three groups (A, B, and C) and treated as follows. Group A was treated with markedly conical, flat-ended spreaders (A to D; Dentsply-Maillefer, Ballaigues, Switzerland). Group B was treated with slightly conical (15 to 40) sharp-pointed CC-cord spreaders. Group C was treated with CC-cord, slightly conical but flat-ended spreaders. The obturated teeth were decalcified in 7.5% nitric acid to obtain four cross-sections: the first at 2 mm from the apex and then the following three sections at 1-mm intervals. Section thickness was approximately 1 mm. Each section was photographed under a stereoscopic microscope. The following areas were measured on each of the microphotographs using a planimeter: (a) gutta-percha mass, (b) mass of sealer, (c) foreign bodies, and (d) empty spaces. These four areas were added to determine total cross-sectional canal area and then the percent of that area attributable to a and to b + c + d was calculated. The statistical analysis of the data (parametric Student's t test for independent groups) revealed that only in group B was the area occupied by a, the gutta-percha mass, significantly greater at all levels than the area occupied by b + c + d. Next in obturation effectiveness was group C, followed by group A.
