Influence of Voxel Size and Filter Application in Detecting Second Mesiobuccal Canals in Cone-beam Computed Tomographic Images

The Correlation between Intraorifice Distance and the Anatomical Characteristics of the Second Mesiobuccal Canal of Maxillary Molars: A CBCT Study

Introduction

Missing anatomy is one of the main causes of endodontic failures, and accurate knowledge of teeth anatomy is a prerequisite for adequate root canal treatment. The aim of the present cone beam computed tomography (CBCT) study was to describe the anatomical characteristics of the mesiobuccal (MB) root canals of maxillary molars and to understand if a correlation exists between the position of the canal orifices and the anatomical features of the root.

Methods

For the purposes of the study, a total of 100 CBCT scans of maxillary molars with two MB canals were selected and studied. The features of root canal anatomy of the MB root of the same teeth were analyzed and recorded (root length, confluence, and Vertucci classification). The distance between MB1 and MB2 orifices and the palatal orifice were recorded, as well as the distance between the orifices and the line joining the palatal orifice and the others. A statistical analysis was performed by providing descriptive measures, the measure of the correlation between different parameters, and the influence of some of these measures on the presence of a confluence between MB1 and MB2.

Results

It resulted that the most frequent configuration is type II Vertucci. The length measured on the sagittal plane was significantly correlated to the presence of a confluence in the MB root. When the root length was higher than 14.56 mm, the confluence is three times more frequent than when the length is lower (OR = 3.635). The area under the curve (AUC) of the receiver operator characteristic (ROC) curve for length on the sagittal plane was 0.632 (P=0.036).

Conclusions

The presence of a confluence between the MB canals of maxillary molars is correlated to the length of the root that could be measured on the sagittal plane and to the distance between the canal orifices. The relative position of the root canal orifices in relation to anatomic landmarks needs to be further explored.

Ex vivo detection of mandibular incisors' root canal morphology using cone-beam computed tomography with 4 different voxel sizes and micro-computed tomography

BACKGROUND

In recent years, cone-beam computed tomography (CBCT) has been widely used to evaluate patients' root canal anatomy due to its high resolution and noninvasive nature. As voxel size is one of the most important parameters affecting CBCT image quality, the current study evaluated the diagnostic potential of CBCT with 4 different voxel sizes in the detection of double root canal systems and accessory canals (ACs) in permanent mandibular incisors.

METHODS

A total of 106 extracted mandibular permanent incisors were collected from the dental clinics, and then were scanned by using micro-CT with a voxel size of 9 μm. The teeth were then fixed in the tooth sockets of human dry mandibles and scanned by using a CBCT device with 4 different voxel sizes (300, 200, 250, and 125 μm). Four observers detected in blind the root canal morphology of the teeth according to the CBCT images, and the presence or absence of a double root canal system, and the presence or absence of ACs, were scored according to a 5-point scale, respectively. Receiver operating characteristic (ROC) analysis was performed, and DeLong test was used to compare the area under the curve (AUC) values and the micro-CT data was taken as a gold standard.

RESULTS

Among 106 sample teeth, 25 specimens with a double root canal system were identified by the micro-CT. ROC curve analysis of the data obtained by the four observers showed that in the detection of double root canal systems, the AUC values ranged from 0.765 to 0.889 for 300 μm voxel size, from 0.877 to 0.926 for 250 μm voxel size, from 0.893 to 0.967 for 200 μm voxel size, and from 0.914 to 0.967 for 125 μm voxel size (all p < 0.01). In general, we observed a trend that the AUC values, sensitivity, and specialty increased with the decrease in the voxel size, and significantly higher AUC values were detected in 125 μm voxel size images. In the detection of ACs, ROC curve analysis showed that among the four observers, the AUC values ranged from 0.554 to 0.639 for 300 μm voxel size, from 0.532 to 0.654 for 250 μm voxel size, from 0.567 to 0.626 for 200 μm voxel size, and from 0.638 to 0.678 for 125 μm voxel size. CBCT images at a voxel size of 125 μm had a weak diagnostic potential (AUC: 0.5-0.7, all p < 0.05) in the detection of AC, with a lower sensitivity ranging from 36.8 to 57.9% and a higher specialty ranging from 73.6 to 98.8%.

CONCLUSIONS

CBCT with 300 μm voxel size could only provide moderate diagnostic accuracy in the detection of a double canal system in mandibular incisors. CBCT with a voxel size of 125 μm exhibited high diagnostic value in the detection of double canal systems, while showing low but statistically significant value in the detection of ACs.

Could Low-dose Cone-beam CT be Used for Endodontic Intraoperative Diagnosis?

INTRODUCTION

Cone-beam computed tomography (CBCT) allows three-dimensional evaluation and has high diagnostic accuracy of endodontic conditions. Considering that the most indicated protocol for endodontics should have smaller field-of-view and higher spatial resolution, a higher radiation dose may be associated. Thus, this study evaluated the accuracy of an optimized CBCT protocol for the detection of intraoperative endodontic complications.

METHODS

An image phantom was custom-made with a human mandible covered with Mix-D and forty mandibular first molars. The teeth were subdivided into 4 groups of endodontic complications which were simulated. All teeth were individually inserted into the left second molar socket of the phantom and CBCT images were acquired with OP 300 unit adjusted to a field-of-view of 6 × 4 cm, 90kVp, and 2 dose protocols: low and high. Furthermore, a titanium implant, a tooth with endodontic treatment, and a cobalt-chromium post were inserted into the empty sockets adjacent to the teeth of interest and additional images were acquired. Four endodontists evaluated the images and indicated the presence of endodontic complications on a 5-point scale. Sensitivity, specificity, and area under the receiver operating characteristic curve were obtained. The different groups were compared by ANOVA and Tukey tests (α = 0.05).

RESULTS

In most conditions, irrespective of the presence of metallic materials, the values of accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve did not differ significantly (P > .05) between the dose protocols.

CONCLUSIONS

Optimized CBCT protocols should be considered for the detection of intraoperative endodontic Diagnostic complications.

Assessment of the Prevalence of Middle Mesial Canal in Mandibular First Molar: A Multinational Cross-sectional Study with Meta-analysis

BACKGROUND

An additional canal found in the mandibular first molar (M1M) is the middle mesial canal (MMC), which is often missed during root canal treatment. In this study, the prevalence of MMC in M1M on cone-beam computed tomography (CBCT) images was evaluated in 15 countries, along with the effect of some demographic factors on its prevalence.

METHODS

Deidentified CBCT images were scanned retrospectively, and the ones including bilateral M1Ms were included in the study. A written and video instruction program explaining the protocol to be followed step-by-step was provided to all observers to calibrate them. The CBCT imaging screening procedure consisted of evaluating three planes (coronal, sagittal, and axial) after a 3-dimensional alignment of the long axis of the root(s). The presence of an MMC in M1Ms (yes/no) was identified and recorded.

RESULTS

In total, 6304 CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference was found between countries (P < .05). MMC prevalence ranged from 1% to 23%, and the overall prevalence was 7% (95% confidence interval [CI]: 5%-9%). No significant differences were found between the left and right M1M (odds ratio = 1.09, 95% CI: 0.93, 1.27; P > .05) or between genders (odds ratio= 1.07, 95% CI: 0.91, 1.27; P > .05). As for the age groups, no significant differences were found (P > .05).

CONCLUSIONS

The prevalence of MMC varies by ethnicity, but it is generally estimated at 7% worldwide. Physicians must pay close attention to the presence of MMC in M1M, especially for opposite M1Ms, due to the prevalence of MMC being significantly bilateral.

Middle mesial root canals in mandibular molars: prevalence and correlation to anatomical aspects based on CBCT imaging

OBJECTIVES

To determine the prevalence of middle mesial root canal (MMC) in a Brazilian subpopulation, verify whether its presence is related to anatomical characteristics of the tooth, and propose a classification using cone-beam computed tomography (CBCT).

METHODS

CBCT scans of 284 patients were evaluated by 2 radiologists to determine the presence of the MMC in mandibular first and second molars. Subsequently, the mesiodistal and buccolingual measurements of the mesial roots were obtained; the measurements between the root canals, and from MMC to the mesiobuccal canal and to the mesiolingual canal were also obtained. The MMC was classified according to its relationship with mesiobuccal and mesiolingual canals. The data were analyzed using χ2 and Fisher's exact test, multiple logistic regression analysis, Student's t-test, κ and intraclass correlation coefficient (p < 0.05).

RESULTS

The intraexaminer agreements for the presence of the MMC and the measurements were considered almost perfect (0.953 and 0.999, respectively). Of 216 mandibular first molars, 11.1% had the MMC, and of 228 mandibular second molars, only 1.75% had the MMC. The presence was significant higher in the mandibular first molar (p < 0.0001). The buccolingual measurement and the measurement between mesiobuccal and mesiolingual canals were higher in teeth with MMC (p = 0.024 and p = 0.005, respectively). It was possible to classify the configuration of MCC into four types: independent (60.7%), confluent (14.3%), mesiolingual confluent (14.3%), and mesiobuccal confluent (10.7%).

CONCLUSIONS

The prevalence of MMC is more pronounced in mandibular first molars and anatomical measurements, such as greater measurement between mesiobuccal and mesiolingual canals, may alert clinicians to its presence. It was found four types of configurations of MMC.