Apical Anatomy of Maxillary First Premolars in an Iraqi Sub-Population: A Micro Computed Tomographic Study

Objectives To investigate the apical root canal anatomy of maxillary first premolars in an Iraqi sub-population using micro-computed tomography (micro-CT). Materials and Methods A total of 151 extracted maxillary first premolars were collected and scanned using micro-CT. Images were segmented and three-dimensionally (3D) reconstructed using Mimics software. The apical constriction (AC) for each canal was located and distances were measured from the AC to the major apical foramen (MAF), to the anatomic apex (AA) and from MAF to AA. The longest and shortest canal diameters at AC were also measured. The cross-sectional canal shape at the AC and the direction of the MAFs were determined. Qualitative data were analysed using the Chi-Square test while quantitative data were analysed with the Independent-Samples T-test and One-Way ANOVA with Bonferroni post hoc tests and respective non-parametric tests at a significance level of 0.05. Results Out of the 151 included maxillary first premolars, 82 (54.3%) were double rooted and 69 (45.7%) were single-rooted. The mean AC-MAF, AC-AA and MAF-AA distances were 0.49 mm ± 0.32 mm, 1.13 mm ± 0.56 mm and 0.74 mm ± 0.49 mm, respectively. The AC to AA and MAF to AA distances were significantly larger in the palatal canals compared to both the buccal and single canals ( P  < 0.05). The mean shortest and longest canal diameters at the AC were 0.18 mm ± 0.06 mm and 0.25 mm ± 0.1 mm, respectively, with 89.8% of the canals having oval cross-sectional shapes at AC. The two diameters were significantly smaller in the buccal canals compared to the palatal and single canals ( P  < 0.05). In 74.2% of the canals, the MAFs were deviated to one of the root sides, mostly to the palatal and distal aspects. Conclusions The apical anatomy of maxillary first premolars is complex and variable in the studied Iraqi population. The majority of the canals had oval cross-sectional shapes at the AC with majority of MAFs showing deviation from the root axis.