Abstract
BackgroundBetter understanding of the danger zone anatomy in mesial roots (MRs) of mandibular first molars (MFMs) may serve to decrease the risk of mishaps. This study aimed to measure the minimal distal dentine thicknesses of danger zone in MRs of MFMs in a native Chinese population using cone-beam computed tomography (CBCT).MethodsCBCT images of 1792 MFMs from 898 Chinese patients were analyzed. The minimal distal dentine thicknesses of the mesiobuccal (MB) and mesiolingual (ML) canals below the furcation 1, 2, 3, 4, 5 mm were measured. The association between the minimal distal dentine thicknesses and the root lengths, patient’s age and gender, side were assessed.ResultsThe minimal distal dentine thicknesses of MB and ML canals are located 3 ∼ 4 mm below the furcation for both men and women. There are no differences between MB and ML canals, while the minimal distal dentine thicknesses of MB and ML canals were higher in men than women (P < 0.05), except at 1 and 3 mm of ML canals (P > 0.05). The minimal distal dentine thicknesses of MB and ML canals increased with age in both men and women at each location (P < 0.05). The minimum distal dentine thickness at every location were significantly different between long teeth and short teeth both in men and women (P < 0.05), with short teeth having the smallest mean values. There are no significant differences between two sides (P > 0.05).ConclusionsThe minimal distal dentine thicknesses of MRs in MSMs have close correlation with root length, patient’s age and gender.
Highlights
Better understanding of the danger zone anatomy in mesial roots (MRs) of mandibular first molars (MFMs) may serve to decrease the risk of mishaps
There are no differences between MB and ML canals, while the minimal distal dentine thicknesses of MB
The results showed that the minimal distal dentine thicknesses of MB and ML canals are located 3 ∼ 4 mm below the furcation for both men and women, with a mean range of 0.78 ∼ 0.80 mm, and there are no differences between MB and ML canals
Summary
Better understanding of the danger zone anatomy in mesial roots (MRs) of mandibular first molars (MFMs) may serve to decrease the risk of mishaps. MFMs seem to be the most frequent endodontically treated teeth, with an incidence as high as 17.0% [1] They usually have 2 or 3 roots, with 2 or 3 canals in the mesial roots (MRs) [2]. Sauáia et al [5] reported that there was a significant difference in the minimum thickness of the distal root wall of the mesiobuccal (MB) canal of MFMs 2 mm below the furcation between long root teeth and short root teeth. The thinnest walls and the deepest concavities in the distal walls of the MRs were found in the longest teeth They suggest that long molars may have a higher risk of strip perforation in MB canals if flared to a larger size [5]. The thickness of the dentine in the danger zone has been studied widely, there are little information in the literatures correlating these measurements with other features of the teeth, such as patient’s age and gender
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