| Abstrakt: |
Paqué F, Zehnder M, Marending M. Apical fit of initial K-files in maxillary molars assessed by micro-computed tomography. International Endodontic Journal, 43, 328–335, 2010. Aim To two- and three-dimensionally assess the fit of the first K-file binding at working length after a crown-down canal procedure. Methodology Twelve maxillary molars with fully developed roots and four separate root canals were selected. Canals were pre-flared using ProFile 0.04 instruments to three quarters of estimated working length (WL). WL was electronically determined using an ISO 06 K-file. Progressively larger K-files were inserted passively to WL. The first binding file was termed initial apical file (IAF). On micro-computed tomography (μCT) scans, cross-sectional areas of IAFs and canals and the largest and smallest root canal diameters were measured 1 mm from instrument tips. Volumes of the apical 2 mm of the instruments and corresponding root canal sections were calculated, and file binding was assessed. Results IAF sizes ranged from ISO-size 0.08–0.30 and were lowest in second mesiobuccal and highest in palatal canals. Files bound in the apical 2 mm in 96% of the canals. The mean canal area filled by the instruments 1 mm from the tip was below 40% in all canal types, the filled volume below 50% (anova, P > 0.05). The mean ratio (±SD) between largest and smallest canal diameter was 3.0 ± 2.6 for first mesiobuccal, 3.3 ± 2.6 for second mesiobuccal, 4.1 ± 3.5 for distobuccal and 1.6 ± 0.4 for palatal canals, indicating oval to flattened cross-sections. Conclusions Two- and three-dimensional analysis of μCT scans revealed that whilst IAFs bound in the apical area, their fit was poor, because their shape does not correspond to maxillary molar canal anatomy. [ABSTRACT FROM AUTHOR] |
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