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

Abstract

Aim

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

Methodology

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: 1. after 30 d wet storage, 2. after 2 h dry time, 3. after 48 h wet storage, 4. after 24 h dry time, 5. after 48 h wet storage, 6. 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 5 calibrated blinded observers. Statistical analysis was performed by nonparametric analysis of variance for longitudinal data (P < 0.05).

Results

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).

Conclusions

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.

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