Radiographic and micro-computed tomography classification of root canal morphology and dentin thickness of mandibular incisors

Abstract

Context: Root canal anatomy is evaluated using different methodologies.

Aims: The aim of this study is to evaluate and classify root canal morphology and dentin thicknesses (DT), comparing radiographic and micro-computed tomography (CT) analysis.

Materials and methods: Canal diameter and DT of mandibular incisors (n = 520) were evaluated using digital radiographs in buccolingual (BL) and mesiodistal (MD) directions. The diameter ratio (DR) BL/MD was classified: flattened (FL, DR >4); oval (OV, 2≤ DR ≥4); rounded (RN, 1.1< DR >2); round (RO, 0.9≤ DR ≥1.1); and with BL flatness (BL, DR <0.9). OV (n = 110) were subjected to micro-CT. DT and DR were evaluated at 3, 6, and 9 mm. ANOVA, Tukey, and paired Wilcoxon tests (P < 0.05) were used.

Results: Radiographic classification was 23.3% FL, 41.3% OV, 27.3% RN, 4.5% RO, and 3.6% BL. DT was similar. Radiographic DT at 3 and 9 mm was greater than micro-CT (P < 0.05) and was similar at 6 mm (P > 0.05). DR differed between the analyses. Oval canals were predominant at all levels radiographically and at 9 and 6 mm in micro-CT analysis, with greater variation at 3 mm.

Conclusion: Oval root canals are predominant in mandibular incisors at 9 mm. Radiographic DT is larger than observed in micro-CT at 3 and 9 mm, and the classification differed in each root level. The classification at 9 mm is indicated.

Keywords: Endodontics; X-ray microtomography; radiography; root canal anatomy.

Figure 1

(a) Buccolingual and mesiodistal radiographic images (I). Analysis of mesiodistal and buccolingual diameter (D) of root canal at 9 mm from the apex (II). Classification according to the observed diameter ratio buccolingual/mesiodistal (III). (b) Radiographic images (I) used to analysis the dentin thickness of mesial (M) and distal (D) (II) dentin walls and e buccal (B) and lingual (L) (III) at 3 and at 9 mm from the apex

Figure 2

(a) Diameter mesiodistal (a1, a3, a5) and buccolingual (a2, a4, a6) evaluated in radiographic images (red lines). Diameter ratio (b1, b2, b3) observed (blue lines) in micro CT images at 3 (I), 6 (II) e 9 (III) mm from the apex. (b) Images obtained using CTAn software and measurements of dentin thickness (white lines) of mesial (M) e distal (D) dentin walls at 3 (IV), 6 (V), and 9 (VI) mm from the apex. Different letters in each column indicate statistically significant differences (P < 0.05)