Moisture content of root canal dentine affects detection of microcracks using micro-computed tomography

To evaluate the effect of moisture content in root canal dentine on detection of microcracks using micro-computed tomography.

Ten roots with and without craze lines or cracks (each n = 5) were selected and scanned six times with different moisture conditions of root dentine using a micro-CT scanner at a high resolution of 10.5 μm. Scanning conditions were as follows: (i) after 30-day wet storage, (ii) after 2-h dry time, (iii) after 48-h wet storage, (iv) after 24-h dry time, (v) after 48-h wet storage, (vi) after 2-h dry time. From each scan, cross-sectional images were obtained at intervals of 1 mm (total n = 708) and evaluated for the presence of dentinal microcracks twice by five calibrated blinded observers. Statistical analysis was performed by nonparametric analysis of variance for longitudinal data (P < 0.05).

Intra-rater percentage agreement ranged between 92% and 98%, whereas inter-rater percentage agreement was 81% and 83%, respectively. No significant differences between all wet groups as well as between both groups with 2-h dry time were detected (P > 0.05). Almost no cracks were observed after wet storage with a significant increase of cracks after 2-h dry time (P < 0.001). Significantly more microcracks were identified after 24 h than after 2-h dry time (P < 0.004).

Moisture content of dentine influenced detection of microcracks when evaluated using micro-CT. Scanning should be performed on dried specimens to allow reliable identification of dentinal defects. Formation of new cracks during dry periods up to 24 h was disproved.