Revisiting Premolars Using Cone-Beam Computed Tomography Analysis and Classifying Their Roots and Root Canal Morphology Using Newer Classification

Micro-computed tomography analysis and ex-vivo detection of six root canals in a four-rooted mandibular first premolar

BACKGROUND

Mandibular first premolar teeth show a wide range of root and canal anatomical variations including accessory roots, deep root proximal grooves and multiple canals. This study provides qualitative and quantitative morphological analysis of a rare four-rooted mandibular first premolar scanned using micro-CT. In addition, it provides clinical implications through endodontic access cavity preparation and negotiation of canals under dental operating microscope (DOM) to assess the difficulty for locating the canals.

METHODS

An extracted four-rooted mandibular first premolar tooth sample was subjected to 2D radiographic imaging in two views and micro-computed tomography (micro-CT) scanning with a resolution of 25 μm. Subsequently, 3D- reconstruction of the tooth sample was performed using Mimics software (Materialise, Leuven, Belgium). 3D (volume and surface area) and 2D measurements (distances between orifices, area, perimeter, maximum and minimum diameter, roundness, aspect ratio and form factor) were obtained. In addition, endodontic access was prepared, and the canals were explored under the DOM. Location of the canals were confirmed by periapical radiographs with the aid of hand files.

RESULTS

The 2D imaging showed the presence of four canals. Micro-CT analysis showed a complex canal anatomy which was classified using Ahmed et al. coding system as 444 MB1-2-1-2 DB2-1-2-1-3-2-3 1(ML1 DL1). Quantitative analysis showed that the MB root had the highest canal volume and surface area compared to other canals. The 2D measurements showed wide variations among canals, which reflects the complexity of the canals in terms of size and geometry. The MB and DB canals tend to have more aspect ratio values (more oval/flattened) than other canals. After access cavity preparation and exploration, six root canals were identified [mesio-buccal one (MB1), mesio-buccal two (MB2), disto-buccal (DB), mesio-lingual (ML), disto-lingual (DL) and lingual disto-buccal (LDB)]. The canals in the MB root showed two locations of splitting.

CONCLUSIONS

Mandibular first premolars may have complex variations in the number of roots and canal configurations. The different anatomical presentations demonstrated in the 2D and 3D measurements of the six canals presented in this report signifies the anatomical variabilities, which could complicate the detection and negotiation of canals during root canal treatment. Ahmed et al. coding system is useful in classifying teeth with complex root and canal anatomy.

Systematic review and meta-analysis of root morphology and canal configuration of permanent premolars using cone-beam computed tomography

INTRODUCTION

The efficacy of root canal treatment is greatly impacted by a thorough understanding of root canal anatomy. This systematic review and meta-analysis aim to thoroughly investigate the root morphology and canal configuration (RMCC) of permanent premolars (PMs).

METHODOLOGY

A comprehensive analysis was conducted following the PRISMA guidelines. Literature exploration was carried out across four electronic databases (PubMed, Embase, Cochrane, and Web of Science). The risk of bias assessment was conducted for the included studies utilizing the Anatomical Quality Assessment (AQUA) tool. Data analysis was performed utilizing SPSS and RevMAN5.3.3. The meta-analysis was applied with a 95% confidence interval to calculate odds ratios (OR).

RESULTS

Among the 82 selected studies, 59 studies exhibited potential bias in domain one (objective(s) and subject characteristics), followed by domain three (methodology characterization). The majority of maxillary PM1s had either single root (46.7%) or double roots (51.9%), while three-rooted variants were uncommon (1.4%). Conversely, most other PMs exhibited a single root. In terms of canal configuration, maxillary PM1s predominantly featured double distinct canals (87.2%), with the majority of maxillary PM2s displaying either a single canal (51.4%) or double canals (48.3%). Mandibular PMs were primarily characterized by single canals, accounting for 78.3% of mandibular PM1s and 90.3% of mandibular PM2s. Subgroup analyses revealed higher incidences of single-rooted and single-canalled PMs among Asians compared to Caucasians. Additionally, women exhibited a higher incidence of single-rooted PMs, while men showed a greater frequency of double-rooted PMs.

CONCLUSIONS

The comprehensive analysis indicated that maxillary PM1s predominantly possess double roots and double canals, whereas maxillary PM2s and mandibular PMs were primarily characterized by single-rooted with a single canal. Notably, single root and single canal were more prevalent among women and Asian samples.

Evaluating the Internal Anatomy of Maxillary Premolars in an Adult Saudi Subpopulation Using 2 Classifications: A CBCT-Based Retrospective Study

BACKGROUND Understanding the root canal morphology is important for successful endodontic treatment. This retrospective cone-beam computed tomography (CBCT) study aimed to compare the adult maxillary premolars (MP), root, and canal morphology among a Saudi Arabian subpopulation based on Vertucci and Ahmed classifications. MATERIAL AND METHODS Scans of 1336 MP - 656 first premolars (MFP) and 680 second premolars (MSP) - were analyzed for the number of roots, morphology of the canals, and symmetry among them. The data were grouped based on the traditional preestablished Vertucci system and newer instantaneous code-based Ahmed classification. Comparative analysis was done using the chi-square test. RESULTS Two roots were common in MFP with 84.4% of the population, followed by those with 1 root and those with 3 roots. In MSP, single roots were more common. The results were non-significant with P values of 0.859 and 0.471, respectively. Most of these MFP had Type IV Vertucci configuration/²TNB¹P¹ Ahmed et al code (TN-tooth number, B-buccal canal, P-palatal canal). In MSP, Type I Vertucci/¹TN¹ Ahmed et al code was most common. However, the results were not statistically significant for the PM with P values of 0.997 and 0.732, respectively. Sex-based difference among them for the roots and root canals was also non-significant. Symmetry among PM in opposite quadrants was 87.1% in MFP and 90% in MSP. CONCLUSIONS Two roots with Type IV (²TNB¹P¹) and 1 root with Type I (¹TN¹) were most common in MFP and MSP, respectively. Symmetry among opposing PM was high.