Influence of cervical preflaring on determination of apical file size in maxillary premolars: SEM analysis

Abstract

The purpose of this study was to investigate the influence of cervical preflaring on the determination of the first file that binds at working length (WL) in buccal roots of maxillary premolars. Five groups (n=10) were formed at random and, after standard access cavities, the WL was determined 1 mm short from the apex. In group 1, the initial apical file was inserted without preflaring of cervical and middle thirds of the root canals. In groups 2 to 5, the cervical and middle thirds were enlarged with sizes 90 and 110 Gates-Glidden drills, K(3) Orifice Opener instruments, ProTaper instruments and LA Axxess burs, respectively. Canals were sized manually with K-files, starting with No. 08 K-files inserted passively up to the WL. File sizes were increased until a binding sensation was felt at the WL and the size of the instrument was recorded. Transversal sections of the WL regions were examined under scanning electron microscopy and the discrepancies between the canal diameter and first file to bind at the WL were assessed. Significant differences (p<0.001) were found between the groups. The major discrepancy was found without preflaring (mean 157.8 microm). LA Axxess burs produced the smallest discrepancy (mean 0.8 microm). Gates-Glidden drills and K(3) Orifice Opener instruments showed no significant differences (p>0.05) between their results (83.2 microm and 73.6 microm, respectively). The discrepancy for ProTaper instruments was 35.4 microm on average. In conclusion, the instrument binding technique for determination of the anatomical diameter at the WL was not precise. Preflaring of the cervical and middle thirds improved the determination of the anatomical diameter at the WL, and the type of instrument played a major role. Canals preflared with LA Axxess burs showed a more accurate binding of the files to anatomical diameter.

Influence of the Cervical Enlargement in Determining the Diameter of the First File and Establishing the Working Length

“…Studies attest to the efficiency and safety of the files used for this phase of treatment with wide range of endodontic techniques that highlight the importance of this procedure prior to instrumentation of the apical region, in order to improve the quality of root canal preparation. [6][7][8][15][16][17] Associated with this, the correct determination of the length of work permits to establish with greater security, not only that the limit should be cleaning and shaping the canal, but also lets you choose the tool with which to start the preparation and how much will be needed enlarge it. Especially in cases of severe curvature teeth, there is more difficulty in apical preparation as a consequence of dentin at the entrance of the root canal.…”

“…These results are in agreement with those found by other authors. [6][7][8][15][16][17][19][20][21] The group using Gates-Glidden drills and stainless steel hand files had a higher increase in the diameter of the file when compared to the system ProTaper and K3. It is likely that the use of drills and hand tools promoted greater dilation of the cervical and middle thirds, an important factor for more precise adjustment of apical file.…”

Avaliação histológica da limpeza dos canais radiculares promovida por diferentes métodos de irrigação e análise tomográfica da área apical no comprimento de trabalho

“…A determinação in vitro do diâmetro anatômico apical tem sido muito pesquisada (BARROSO et al, 2005;IBELLI et al, 2007;PAQUÉ et al, 2010;PÉCORA et al, 2005;SCHMITZ et al 2008;VANNI et al, 2005;WU et al, 2000;WU et al, 2002). Os autores afirmam que o melhor resultado na seleção do instrumento apical inicial mostrou-se mais preciso quando o preparo cervical foi previamente realizado.…”

“…Assim, neste trabalho, o preparo cervical dos dentes foi realizado com brocas L.A. Axxess ® , pela sua eficácia (BARROSO et al, 2005;IBELLI et al, 2007PÉCORA et al, 2005VANNI et al 2005).…”

“…No entanto, em estudos sobre a correta detecção do diâmetro anatômico da região apical no comprimento de trabalho (CT), foi ressaltada a importância do preparo cervical, uma vez que esse procedimento tende a auxiliar na correta seleção do instrumento inicial, levando a um adequado alargamento do terço apical (BARROSO et al, 2005;IBELLI et al, 2007;PAQUÉ;MARENDING, 2010;PÉCORA et al, 2005;SCHMITZ et al 2008;WU et al, 2000).…”