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Three-dimensional morphological analysis of C-shaped canals in mandibular first premolars in a Chinese population.

AIM
To investigate and compare the unique anatomical features and positioning of C-shaped canals in mandibular first premolars with and without radicular grooves in a Chinese population.


METHODOLOGY
A total of 327 extracted mandibular first premolars including 146 with radicular grooves and 181 without radicular grooves from a Chinese population were scanned by μCT-50 or μCT-80. After reconstruction, canal systems were classified according to a modified Vertucci method and the anatomical features evaluated. The data were analysed by one-way anova test, Chi-square test and Fisher's exact test (P < 0.05).


RESULTS
Of 146 mandibular first premolars with a radicular groove, 97 had C-shaped canals, the predominant anatomical canal type being Vb (P < 0.001), which was characterized by an oval canal in the coronal part and a semicolon or continuous C-shape beneath the groove. Of the 181 mandibular first premolars without a radicular groove, no C-shaped canal system was observed, and the percentage of Ia (97.8%) was significantly higher than those of other types (P < 0.001).


CONCLUSION
In teeth from a Chinese population, mandibular first premolars with radicular grooves had a high incidence of C-shaped canal systems with anatomical variations along the root.