Comparative evaluation of tip diameter of different gutta-percha cones according to ISO 6877 measurement method and direct measurement method: an in vitro study

Objectives: Accurate fitting of the gutta-percha master cone is essential to ensure apical sealing and the success of endodontic treatment. The purpose of this study was to analyze the dimensional variability of gutta-percha cones by assessing the conformity of their apical tip diameter to manufacturer-specified values, and to compare tip diameter (D0) determination according to ISO 6877 with a direct measurement method. Methods: Ten size 25/.06 and ten size 30/.04 gutta-percha cones from ten commercial brands were evaluated. The apical tip diameter was determined according to the ISO 6877 measurement protocol and compared with a direct measurement obtained using a profilometer. Results: A substantial number of gutta-percha cones exhibited apical tip diameters that did not correspond to manufacturer-declared values. ISO 6877-based determination of D0 yielded heterogeneous results, likely due to morphological irregularities and taper variations. In contrast, direct measurement provided more homogeneous values that were generally closer to the nominal diameter. Cones manufactured using an injection molding process demonstrated the highest dimensional consistency. Conclusions: These findings highlight the need to revise the dimensional tolerances defined by ISO standard 6877. The adoption of more precise manufacturing and quality-control processes, together with the use of direct measurement as a complementary assessment tool, may improve the reliability of the nominal dimensions of gutta-percha cones.