Root dentine thickness of danger zone in mesial roots of mandibular first molars

Abstract

Background: Better 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). Methods: CBCT 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. Results: The 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). Conclusions: The minimal distal dentine thicknesses of MRs in MSMs have close correlation with root length, patient's age and gender.

Evaluation in the danger zone of mandibular molars after root canal preparation using novel CBCT software

“…13,14 In both MB and ML canals, the safe thickness values for preparations using various instrument systems, such as ProTaper Next ® , BioRace ® , Reciproc Blue ® and WaveOne Gold ® , were not significantly different. Zhou et al 24 measured the thinnest distal dentin in the danger zone of the mesial roots of mandibular first molars in a Chinese population using CBCT images. In MB and ML canals, it was at about 3-4 mm from the furcation.…”

“…(C) A color map was used to check the densities of the cementum-dentin structure. Several studies 10,11,[13][14][15][16][17][18][19][20][21][22][23][24]28 compared the dentin removal in the danger zone of mandibular molars. They used different instrumentation techniques and evaluation methods, such as histometry, periapical radiographs, micro-CT and CBCT.…”

“…[10][11][12][13][14] Several methods have been used to evaluate the amount of dentin remaining in the danger zone of mandibular molars after instrumentation using different techniques. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Cone-beam computed tomography (CBCT) has been used as a method of investigation in different areas of dentistry, particularly endodontics. 25 Its use is fundamental to preserving the samples in laboratory studies, and providing knowledge about patient age and gender in clinical studies.…”

A critical analysis of laboratory and clinical research methods to study root and canal anatomy

“…For root and canal anatomy studies, CBCT has been used for the investigation of root and canal anatomy in different population groups (including gender, age and bilateral symmetry) (Akbarzadeh et al, 2017; Betancourt et al, 2016; Karobari et al, 2021; Kim et al, 2013a; Martins et al, 2017; Senan et al, 2020) (Figure 27), in addition to some quantitative measurements (Figure 28), such as tooth/root lengths, distances between root canal orifices (Zhang et al, 2017b), distance between root canal orifice and the external root surface (Akbarzadeh et al, 2017), root dentine thickness (Zhou et al, 2020), angles for root curvatures (Zhang et al, 2015), angles between canal orifices (Zhang et al, 2015), levels of canal merging and splitting (Martins et al, 2017) in addition to studies related to specific anatomical variations such as mandibular molars with disto‐lingual roots (Kim et al, 2018), C‐shaped canals (Brea et al, 2021) and dens invaginatus (Różyło et al, 2018).…”

A micro‐CT analysis of radicular dentine thickness in mandibular first premolars presenting C‐shaped root canals: Identification of potential danger zones

“…The characteristics of the danger zones and their consequent clinical implications have been extensively analysed in maxillary premolars (Liu et al, 2019(Liu et al, , 2021 and mandibular and maxillary molars (De-Deus et al, 2019Ordinola-Zapata et al, 2019;Zhou et al, 2020). However, in mandibular first premolars, the relationship between the C-shaped canal morphology and the presence of danger zones has been scarcely studied, and the identification of thin dentine areas susceptible to perforations or wear has been only reported in studies describing biomechanical preparations (Cerqueira et al, 2021).…”