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

Abstract

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 μm), the specimens were distributed into 3 groups (n = 8 molars): Reciproc®, ProTaper Next™ and Mtwo®. 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.

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

“…Nevertheless, the acquisition of such dentoalveolar bone-blocks is time-consuming and challenging. Obtaining suitable samples for the present study, especially fresh-frozen bone-blocks, was very difficult and requires a well working cooperation between different institutions [ 25 ]. However, the final sample size of 10 teeth in each group is comparable with recent investigations [ 25 , 46 ] and complied with previous sample size calculations for such research [ 23 ].…”

“…In extracted teeth, the prevalence of preoperative microcracks in non-endodontically treated teeth was found to be significantly higher in old than in young patients [ 17 ]. Moreover, recent micro-CT studies using dentoalveolar bone-blocks from old donors aged between 60–80 years and between 45–95 years identified in 9.5% respective 50% of the specimens preoperative defects [ 25 , 26 ].…”

“…So far, there are only few studies available combining the in situ cadaveric model with micro-CT analysis when investigating the phenomenon of microcrack formation [ 22 , 23 , 25 , 26 ]. These studies only included one of the two preserved bone blocks: either frozen or embalmed.…”

The endodontic‐periodontal juncture: Where two worlds meet. An overview of endo‐perio lesions

“…It is also now recognized that cementum can delaminate from the underlying dentine in localized areas referred to as ‘cemental tears’ 20 . It is thought that some teeth have an inherent weakness at the junction of the cementum and dentine which predisposes them to cemental tears, and occlusal stresses and trauma are also believed to be involved in cleaving small islands of cementum away from the dentine 21 .…”

“…It is also now recognized that cementum can delaminate from the underlying dentine in localized areas referred to as 'cemental tears'. 20 It is thought that some teeth have an inherent weakness at the junction of the cementum and dentine which predisposes them to cemental tears, and occlusal stresses and trauma are also believed to be involved in cleaving small islands of cementum away from the dentine. 21 The endodontic and periodontal literature is replete with case reports of cemental tears; however, very little is known about their causes, prevalence or their role in periodontal and endodontic disease.…”