Histological evaluation of refinement influence in the cleaning efficacy of rotary nickel-titanium ProTaper® instruments in oval-shaped root canals

Resumo

The aim of this in vitro study was to evaluate the
cleaning and shaping efficacy of rotary nickel-titanium ProTaper®
instrumentation in oval canals and the influence of ultrasonic
irrigation on the final refinement. Material and methods: Twenty
mandibular molars were accessed and divided in two groups. Only
distal roots with oval canals were used. Group I was instrumented
using only rotary nickel-titanium ProTaper® instruments. Group II
received the same preparation followed by refinement with 3 minutes
of ultrasonic passive irrigation. After preparation, the distal roots
were sectioned for histological processing. Coronal, middle and apical
thirds were analyzed. Uninstrumented perimeter in each third was
measured by the software Image tool 3.0. Results: The percentage
of uninstrumented perimeter was calculated for each third of each
root and average percentage was calculated for each third in both
groups. Statistical analysis was performed with t-test through the
software SPSS 11.0.1 for Windows. The level of significance was
set at 1%. Group I showed higher percentage of uninstrumented
perimeter in all thirds. Group II, which received ultrasonic irrigation
showed better results in all thirds (p < 0.01). Comparing the three thirds in the same group, no statistically significant differences
were found (p > 0.05). Conclusion: Under the conditions of this
ex vivo study, the three minutes use of ultrasonic irrigation after
rotary instrumentation resulted in significantly more instrumented
walls in the distal roots of mandibular molars.