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Influence of a brushing working motion on the fatigue life of NiTi rotary instruments
Author(s) -
Plotino G.,
Grande N. M.,
Sorci E.,
Malagnino V. A.,
Somma F.
Publication year - 2007
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/j.1365-2591.2006.01179.x
Subject(s) - nickel titanium , dental instruments , orthodontics , dentistry , significant difference , sample size determination , materials science , statistical significance , mathematics , medicine , composite material , statistics , shape memory alloy
Aim To evaluate the cyclic fatigue resistance of M two NiTi rotary instruments when used with a brushing or no‐brushing action in oval root canals. Methodology Cyclic fatigue testing of instruments was performed in tapered artificial canals with a 5 mm radius of curvature and an angle of curvature of 60°. Twenty M two instruments for each size were selected and divided into two groups: group A = 10 instruments used with a no‐brushing motion (control group); group B = 10 instruments used with a brushing‐milling action. Each M two instrument was used for cleaning and shaping 10 oval root canals. In all 80 instruments were rotated until fracture occurred and the number of cycles to failure (NCF) recorded. Data were analysed by one‐way anova , Tukey HSD test and independent sample t ‐test to determine any statistical difference; the significance was determined at the 95% confidence level. Results No statistically significant reduction of NCF between instruments used with a no‐brushing motion (group A) and instruments used with a brushing motion (group B) were apparent except for size 25, 0.06 taper. M two size 10, 0.04 taper, size 15, 0.05 taper, size 20, 0.06 taper, size 25, 0.06 taper instruments had a decrease in life span of 1%, 0.5%, 8% and 19%, respectively. Conclusions Fatigue life of instruments of larger size could be reduced by using them with a lateral brushing or pressing movement. However, each file was successfully operated without intracanal failure, demonstrating that M two rotary instruments can be used safely in a brushing action in simulated clinical conditions up to 10 times in oval canals.