Introduction and objective:
When filling root canals with gutta-percha points (GP), good adaptation of the point to the apical diameter must be achieved through the use of a point corresponding to the size of the master apical file (MAF). GP points with a greater taper, designed to fit into root canals shaped with files with a greater taper, are currently in common use. The study was performed to evaluate the ISO compliance of GP greater taper points (4% and 6%).

Material and methods:
Two boxes of GP in sizes 20, 30 and 40 (Dentsply Maillefer, Switzerland) with a taper of 4% (GP 4% group) and 6% (GP 6% group) were used. The percentage of GPs conforming to the ISO size and those not conforming to the ISO size was determined by assessing the fit of the GP apex diameter (D0) with an endodontic gauge (Dentsply Maillefer, Switzerland). Data were analysed using the chi2 test with a significance level of 0.05.

Results:
Overall, 58.9% of the GP points assessed were in accordance with the ISO size. Depending on the size (20, 30, 40 according to ISO), compliance was 75%, 52.5% and 44.4% in the group GP 4%, and 87.5%, 32.5% and 60% in the group GP 6%, respectively. The results were statistically significant in the GP 4% (p<0.0001) and GP 6% (p<0.05) groups. In both groups, standardisation of greater taper GP was most accurate at size 20. There were no statistically significant differences between the number of GP points with correct diameter between groups GP 4% and GP 6%.

Conclusions:
The study demonstrated the presence of differences between the ISO size and the actual size of the greater taper GP points. Therefore, the calibration of greater taper GP points before root canal filling should be a routine procedure.