Dentinal microcracks and cemental tears related to chemo-mechanical root canal instrumentation: a micro-CT Cadaver Study.

BACKGROUND: The prevalence of radicular defects after root canal instrumentation is unresolved. This study used micro-CT to assess the relationship between the formation of radicular defects and chemo-mechanical instrumentation in a cadaver model. METHODS: Maxillary and mandibular molars (n = 24) were sectioned from cadaver specimens as a tissue block containing the teeth, alveolar bone and attached mucogingival tissues. After a baseline micro-CT scan (13.45 mum), the specimens were distributed into 3 groups (n = 8 molars): Reciproc((R)) , ProTaper Next and Mtwo((R)) . Micro-CT scans of each specimen were obtained after access, glide path and preparation with each instrument. The pre-operative and final post-operative micro-CT cross-sectional images of the roots were screened by two blinded examiners to identify any pre-existing and new radicular defects. Pre-existing and new radicular defects were examined histologically. RESULTS: Overall, 16 pre-existing radicular defects were identified in 12 of the 24 molars (50%). Most of these were cemental tears (87.5%), and not true dentinal microcracks. New dentinal microcracks were observed in the post-operative micro-CT scans of only 3 canals (3.9%; 3/77). However, only one of these defects was found to be present histologically. CONCLUSIONS: Within the limitations of the study, chemo-mechanical instrumentation did not routinely promote the formation of radicular defects.