ABSTRACT
Objective: We aimed here to evaluate the enlargement characteristics of two nickel-titanium
rotary instrument systems that use two different preparation techniques, in simulated
root canals under "operator-related variables" standardized conditions. Materials and Methods: A total of 40 simulated canals in resin blocks were divided into two groups as the
Mtwo group for use with a single-length technique and the ProTaper instrument system
group for use with crown down technique. To standardize the operator-related variables,
all preparations were carried out with a computer controlled device that was developed
and used previously as described in a published study. The pre- and post-operative
digital images of the canals were superimposed and measured at 11 levels from the
apical tip. The distances between the pre- and post-operative outer lines of the root
canals were measured at both the inner and outer sides of the curve. The amount of
removed material and the symmetry of the preparations were evaluated. Statistical
analyses were performed with Mann-Whitney test. Results: Significantly more material was removed by Mtwo at 9 levels and by ProTaper at 2
levels (P < 0.05) while no significant difference was determined at 11 levels. The preparations
made with ProTaper were more symmetrical at 4 levels while no significant difference
was determined at 7 levels. Conclusions: Mtwo removed significantly more material than ProTaper at different levels of the
curved root canals. Mtwo and ProTaper made symmetrical preparations and maintained
the original shape of the root canal at different levels under controlled operator-related
variables.
Key words:
Mtwo - preparation symmetry - ProTaper - resin blocks - rotary instrumentation
