Apical displacement produced by rotary nickel-titanium instruments and stainless steel files

Abstract

The aim of this study was to evaluate the apical displacement produced by different rotary nickel-titanium instruments, testing the hypothesis that rotary systems with nickel-titanium instruments produce lower mean values of apical displacement than stainless steel hand instruments. A total of 100 maxillary permanent first molars were selected for the study. The mesiobuccal roots were sectioned at the top cervical third and embedded in blocks of self-curing resin. The specimens were randomly divided into 5 groups and the root canals were prepared using the following nickel-titanium instruments: Group 1 - Quantec system 2000 (Analytic Endodontics, Mexico); Group 2 - Pro-File T.0.04 (Dentsply/Maillefer, Switzerland); Group 3 - Pro-File Series 29 T.0.04 (Dentsply Tulsa, Switzerland); Group 4 - Pow-R T.0.02 (Moyco-Union Broach, USA). Specimens in Group 5 were prepared using stainless steel hand instruments Flexofile (Dentsply/Maillefer, Switzerland). All root canals were previously submitted to cervical preparation using Orifice Shaper instruments #1, 2, 3 and 4 (Dentsply/Maillefer, Switzerland). After odontometry, the remaining root canal was shaped employing increasingly larger instruments, so that the final instrument corresponded to Quantec #9, Pro-File Series 29 #6, and #35 for the other groups. Specimens in Groups 1 to 4 were prepared using an electric handpiece with 16:1 reduction at 350 rpm. The specimens in Group 5 were manually prepared. Apical displacement was measured and recorded by means of radiographic superimposition on a specific desk. Statistical analysis (ANOVA) of the results revealed that all groups presented apical displacements. Considering only the nickel-titanium instruments, Group 4 showed the lowest mean value while Groups 2 and 3 produced the highest mean apical displacement values (p<0.001).

Influence of anatomical features in the endodontic treatment planning of maxillary anterior teeth

“…This data is important when planning biomechanical preparation as instruments with different tapers and/or kinematics must be used to allow greater surface contact of the instrument. 17,18 According to Buchanan, 19 one must be aware of the anatomical differences of each third of the root canal to optimize the function of each instrument.…”

Avaliação, por meio de microtomografia computadorizada, da anatomia interna de dentes anteriores superiores

“…Já nos incisivos centrais, apesar de apresentar também acentuada conicidade, a diferença entre a conicidade dos diâmetros maior e menor foi mais discreta (0,09 mm para o diâmetro maior e 0,07 mm para diâmetro menor). Esse dado torna-se importante no momento do planejamento do preparo biomecânico, em que se deve utilizar instrumentos com diferentes conicidades e/ou cinemáticas que permitiria então maior área de superfície tocada pelo instrumento (VANNI et al, 2004;VANNI et al, 2005). Segundo BUCHANAN (1994), para otimizar a função de cada instrumento é preciso ter conhecimento das diferenças anatômicas de cada terço do canal radicular.…”

Research progress of mandibular first molar preparation with nickel-titanium instruments under the guidance of CBCT

“…The flexibility and fracture resistance of NiTi instruments are 2-3 times higher than those of stainless steel files [27], which makes them more efficient and safer [28]. Another study found that [29], nickel-titanium instruments are less prone to apical deviation than stainless steel instruments, which allows the apical segment to be filled more tightly and improves the success rate of root canal treatment. To sum up, nickel-titanium instruments have the advantages that traditional stainless steel instruments are difficult to replace in various aspects.…”