Micro-CT evaluation of frozen and embalmed human cadavers on the effect of root canal preparation on microcrack formation in old dentin

Abstract

The aim of this study was to evaluate the existence of preoperative dentinal defects among differently preserved dentoalveolar bone-blocks (frozen vs. embalmed) and to investigate the effect of varying apical forces (low: <4 N, high: 4–8 N) during root canal preparation on microcrack formation using micro-computed tomography (micro-CT). Thirteen embalmed and seven frozen bone-blocks containing 1–3 single rooted teeth were collected. The teeth were evenly divided into three groups (n = 10): FLow (frozen, <4 N), ELow (embalmed, <4 N), EHigh (embalmed, 4–8 N). After working length determination all specimens were scanned preoperatively. Root canal preparation was performed using nickel-titanium instruments sizes 25/.06 and 40/.06 (F6 SkyTaper; Komet, Lemgo, Germany). A postoperative scan was performed and image stacks were co-registered. All cross-sectional images were screened to identify the presence of dentinal defects. The results were expressed as the percentage of teeth/slices presenting dentinal defects. The statistical analyses were performed with Kruskal-Wallis-Test and Mann-Whitney-U-Test (α = 5%). Embalmed specimens presented a significantly higher percentage of slices with preoperative microcracks (p<0.05) than frozen specimens. No significant difference between groups was observed regarding the induction of microcracks (p>0.05). Root canal preparation does not induce microcracks in dentoalveolar bone-blocks from donors of old age, irrespective of the preservation method and the apically directed forces.

A review of the latest developments in rotary NiTi technology and root canal preparation

“…The impact of root canal preparation and its kinematics on crack formation has been widely studied with controversial results. [112][113][114] Recently, the impact of this clinical concern, and in general the importance of microcracks, often a common finding when analysing functional teeth in vivo, has been rejected as a crucial factor in the prognosis of root canal treated teeth. [115][116][117][118] Further, the apical extrusion of debris has been extensively investigated with different methodologies, mainly in in vitro studies.…”

The Value of Micro-CT in the Diagnosis of Lung Carcinoma: A Radio-Histopathological Perspective

“…While there are many micro-CT studies investigating tumors in live and sacrificed animals [52][53][54][55][56][57][58][59][60][61][62][63][64][65], this technique can only be used for the examination of ex vivo specimens in the context of human tumors, since the radiation dose used in micro-CT examination is very high compared to a conventional CT [7,66,67]. Both fresh or formalin-fixed specimens can be successfully scanned with micro-CT [26,35,41,42,[68][69][70][71][72] (Figures 1-3; Supplementary Videos S1 and S2); however, the protocols to be employed need to be optimized to obtain the best results. In a study using fresh lung specimens, it was reported that artifacts caused by insufficient air-tissue contrast or tissue deflation could sometimes obscure the target lesion, but these artifacts could be reduced by making some adjustments to the protocol [26].…”