Evaluation of the Root Canal Morphology of Human Teeth by Cone Beam Computed Tomography and Micro-Computed Tomographic - A Systematic Review with Meta-analysis.

Introduction: To thoroughly plan and execute any dental treatment, the anatomy of the dental root canals is of prime significance. Hence, in this systemic review, we intend to evaluate the cone beam computed and micro-computed tomographic presentations of the root canal morphologies of the secondary teeth. Materials and
Methods: We conducted the search for the data from the online sources such as the "EMBASE," "Pubmed," "Scopus," and other sources. Only human studies were collected. Terms searched were cone beam computed tomography (CBCT), micro-computed tomography, permanent teeth, and root canal morphology. The data extraction and meta-analysis were based on the PRISMA guidelines.
Results: A total of 170 studies were initially considered for the study. After the application of the inclusion and the exclusion criteria, only ten studies were qualified for the study. In 2 studies, the comparison was done between the conical beam and the microtomograhic views for assessing the root canal anatomies. There were, however, three studies that did not conclude any significant relation between the two imaging systems. When the risk of bias was calculated for the ten studies, there were only low and moderate for the ten included studies. The pooled prevalence among the genders were 21.4% (14.0%-24.6% confidence interval [CI] 95%) and 25.3% (20.0%-30.7% CI 95%), respectively, with high heterogeneity values (= 99.30% and 98.50%, respectively), but no statistical significance (P > 0.05).
Conclusion: Both the imaging systems CBCT and the microtomography can be used with accuracy in the evaluation of the anatomic variations of the human root canal. However, a definition is dependent on the voxel size. Copyright:

INTRODUCTION

To thoroughly plan and execute any dental treatment, the anatomy of the dental root canals is of prime significance. The anatomy of the dental root canal systems is also of significance for various anthropological and forensic reasons.[1] However, due to complex structure of the canal topography, the detection is always a challenge. These canal structures may range from simple straight to curved and more complex among any of the teeth. These variations in the anatomies of the root canal may vary between the ethnic communities, gender, and races.[123] Various classifications have been provided by the authors describing the root canal structures.[456789] Among these is the Vertucci classification that is most widely followed. The root canal is divided into eight presentations.[10] There are various modalities of the detection of the root canal morphology that may be invasive and noninvasive such as radiography, histological methods, cone beam computed tomography (CBCT), microCT. Among these CBCT is the recent advanced imaging method that has been employed for the detection of the maxillary and mandibular pathologies and structures. It has been preferred over the conventional IOPA because of the greater detail, it produces for the evaluation of an imaged structure. There have been various reports of the significance of the CBCT and/or microCT in the evaluation of any of the groups of the permanent teeth. Hence, in this review, we intend to evaluate the cone beam computed and microCT presentations of the root canal morphologies of all the teeth.

MATERIALS AND METHODS

Review registration and design: The present systemic review and meta-analysis followed the “PRISMA” guidelines. Data search strategy: The articles for the present study were collected from the online databases that included “SCOPUS, PUBMED, EBSCO, EMBASE.” Study selection: The publications for the past 10 years and in English language were considered. The terms that were considered in the search were “root canal and/or microcomputed tomography and/or CBCT and/or permanent teeth.” For the removal of the duplicate articles and the search of the articles, Endnote software was employed. Criteria for the selection of the articles: The following criteria for the inclusion for the review were human root canal morphology, no prior treatment done, imaging by CBCT, and the microcomputed CT. The studies that were not considered were those that were either review articles, clinical trials, and those that were author opinions. The authors were contacted in case there arose a doubt and a clarification was required. After the data were collected, two reviewers independently evaluated the articles for the desired criteria. Of the 87 articles that were considered, only ten studies were finalized for the present review. The data were prepared from the finalized articles and a table was formulated based on the author, type of the teeth, sample size, General feature assessment, and specific feature assessment. Later, the risk of the bias was evaluated by two reviewers. The imaging techniques that were considered were CBCT, microcomputed CT. The voltage, software systems, the voxel, voltage, and amperage were also considered for the finalized studies. Critical appraisal: Two reviewers conducted the evaluation of the articles that were finalized to be included in the meta-analysis. The validity of the studies was divided as low, moderate, and high risk. Statistical analysis: The data were processed using a random-effects model. The software OpenMeta [Analyst] v. 10.10 software (GPL General Public License version 2, MA, USA) software was used to perform the analytic analysis. The final results were displayed as odds ratio forest plots and 95% confidence interval (CI) proportions. The studies heterogeneity was determined with Tau2. The Q-Cochran test and the I2 statistic were used to measure the statistical heterogeneity of the proposed outcomes (low [25%], moderate [50%], and high [75%]). A significant heterogeneity was considered to be present if the I2 value was equal to or above 50%. A meta-regression analysis was performed to understand possible sources of heterogeneity. Statistical significance was set at 5%.

RESULTS

In the obtained total of the 87 articles after the removal of duplicates and the application of the specified criteria, ten articles were finalized [Figure 1]. The data that were obtained from these ten were tabulated as shown in Table 1. The CBCT and the micro-computed CT were considered in all the ten studies. For the clarification of the imaging parameters and the manufacturer, the authors were referred and data obtained was noted. The year of the article publication ranged from 2018 to 2021. A total of 358 patients were considered for the study. We noted that in all these ten articles, the Vertucci's classification of the canals was considered. In the present study, it was noted that 3979 permanent teeth were studied for the root morphologies. All the teeth were imaged by CBCT and the microcomputed tomography along with other imaging techniques. Almost in all the types of the permanent teeth, both the maxillary and mandibular teeth the CBCT and microCT were comparable. Variations noted: The gender variation was presented in 3 studies. The pooled prevalence among the genders were 21.4% (14.0%–24.6% CI 95%) and 25.3% (20.0%–30.7% CI 95%), respectively, with high heterogeneity values (I2 = 99.30% and 98.50%, respectively), but no statistical significance (P > 0.05). Pooled percentages regarding the presence of a normal root canal in the permanent teeth was 5.9% (4.1%-7.7% CI 95%) with a high heterogeneity (I2 = 94.49%) The meta-regression analysis was performed to understand if gender could play as plausible confounding variable in the heterogeneity of canal proportion in the mandibular anterior teeth. Regarding genders, the meta-regression omnibus P = 0.419 (central incisor), 0.512 (lateral incisor), and 0.471 (canine) showed a nonsignificant effect in the explanation of proportion variance Table 2 and Figures 1-4].

Figure 1

Flowchart showing the selection of the articles

Table 1

Chief features in the finalized studies

Author	Permanent teeth type	Sample size	Characteristics of the study	Detailed features evaluated
Alqedairi et al., 2018[9]	Maxillary premolars	707	Comprehensive morphologic characteristics	Gender variations maxillary premolars
Mashyakhy and Gambarini et al., 2019[11]	Maxillary and mandibular all teeth	822	Comprehensive morphologic characteristics	Gender differences in the Root canal configuration
Hussam et al., 2019[4]	Mandibular premolars	707	Comprehensive morphologic characteristics	Detect and measure isthmi
Al-Nazhan, 1991[12]	Maxillary central and lateral incisors in female	02	Evaluation of root canal type by Vertucci’s method	Root and canal areas
Alenazy et al., 2019[13]	Mandibular central and lateral incisors	75	Evaluation of root canal type by Vertucci’s method	Configuration of the mesial root (type I and II)
Mashyakhy et al., 2019[3]	Mandibular first permanent molar	174	Evaluation of root canal type by Vertucci’s method	Root canal configuration of mandibular first permanent molar
Maghfuri et al., 2019[14]	Maxillary premolars	100	Evaluation of root canal type by Vertucci’s method	Root canal configuration
Dallak et al., 2020[2]	Maxillary and mandibular central and lateral incisors	29	Comprehensive morphologic characteristics	Root and canal areas
Al-Madi et al., 2020[15]	Maxillary central and lateral incisors in female	35	Evaluation of root canal type by Vertucci’s method	Root and canal areas
Almohaimede et al., 2021[16]	Maxillary/mandibular canines	1328	Comprehensive morphologic characteristics	Gender variation also in the root canal configuration

Table 2

Comparison of the cone-beam computed tomography/microcomputed tomography values among the included studies

Author	Voxel size	FOV settings	CBCT software	Visualization
Alqedairi et al., 2018[9]	0.3	15 cm3	85 Kv/5-7 mA/	-
Mashyakhy and Gambarini 2019[11]	0.25	100×70×50 mm	90 Kv/5-7 mA/	Horos
Hussam et al., 2019[4]	0.25	-	120 Kv/5-7 mA/	Morita’s i-Dixel 3D
Al-Nazhan S et al., 1991[12]	0.25	-	85 Kv/5-7 mA/	Planmeca Romexis
Alenazy et al., 2019[13]	0.2	Full arch	95 Kv/5-7 mA/	eXam vision
Mashyakhy et al., 2019[3]	0.25	Full arch	92 Kv/5-7 mA/	Horos
Maghfuri et al., 2019[14]	0.2	Full arch	85 Kv/5-7 mA/	Morita’s i-Dixel 3D
Dallak et al., 2020[2]	0.25	Full arch	130 Kv/5-7 mA/	Planmeca Romexis
Al-Madi et al., 2020[15]	0.3	Full arch	90 Kv/5-7 mA/	eXam vision
Almohaimede et al., 2021[16]	0.3	Full arch	85 Kv/5–7 mA/

CT: Computed tomography, CBCT: Cone-beam CT, FOV: Field of view

Figure 4

Prevalence odds ratio forest plots of the root canal according to gender on central (top) and lateral (middle) mandibular incisors and canines (bottom)

The graph for calculating the risk of bias graph with 6 elements for all the studies

The graph for calculating the risk of bias graph with 6 elements taken across ten studies

DISCUSSION

CBCT offers the advantage of being a highly accurate technique that provides three-dimensional images in a noninvasive way, exposing patients to lower doses of radiation than other techniques such as traditional computed tomography. The greatest disadvantage of CBCT in the study of dental anatomy is the presence of image artifacts caused by the presence of highly radiopaque materials from the filling and restoration of the tooth or resulting from other factors such as the patient's movements. Likewise, in in vivo studies, the strong impact of the use of CBCT as a method to study the root canal system is reflected in the high number of samples obtained in some clinical trials, allowing adequate statistical analysis in prevalence studies.[17] In the present systemic review, the ten studies included better comparable imaging for the root canals in the permanent teeth using the CBCT than the conventional techniques.[2349111213141516] In three of the studies, there were disagreements with the root canal assessment of the maxillary teeth isthmus and the total area.[568] None of the studies included were described the incidence of the radis molaris, or any other variations of the normal anatomy to keep out the bias.[18] It was also noted that the images obtained with the CBCT at various specifications among the studies were comparable to the micro CT. It was observed that for the analysis of the outcomes in these studies, various factors effected the final results. For example, the supply voltage and the software used in the imaging technique. Along with the material and standardization of the imaging apparatus, the personnel interpreting the data were also significant. Both the imaging techniques and the canal morphologies when employed these methods were comparable.[19] In the studies, the mandibular laterals the type 3 vertucci canal configuration were in over third.[211121315] When the central and laterals of the mandible were considered, two canals were common findings.[2111315] Furthermore, a similar report was given by the study of WHO in one root mandibular anterior teeth. We observed that in almost all the studies, Vertucci classification was considered, however, the detailed classification was not presented. In our ten studies, when compared, bilaterally symmetrical canals were seen for the maxillary teeth.[21114] This is consistent with the studies conducted in other regions of the world.[2021] The gender distribution of the root canals was observed to be nonsignificant.[91116] There was very less data to compare the findings in the included studies with other region studies as the comparative elements were absent, like CBCT and micro CT. When the imaging settings were considered, we observed that the image quality was dependent on the voltages, amperages, technology. The same was put forward in the study of Tolentino et al.[22] Higher supply of the power was associated with the lesser noise. Contrary to our study Marca et al.[23] stated that CBCT was imprecise for the detection of the root canal morphology. In the study conducted by Freitas et al.,[24] they found a adequate and significant consensus in both imaging techniques. In our review, a thorough conclusion regarding the tube potential on the image output was not presented as the data about the exposure settings in the two imaging methods was not available. It is known that lower/smaller scan volumes give better visualization and resolution of the minute areas of the root canal anatomy. In the included studies, there was no thorough description of the scan volumes or the field of view values. In the study of Tolentino et al.,[22] incoherence between the two imaging systems when the small field of view was implied. However, in the studies of Freitas et al.[24] by the application of Prexion 3D in the diagnosis of MB canal with a similar FOV, described high agreement among the two imaging systems. There were few drawbacks in our study. There was no uniformity in the software used for the imaging techniques. Hence, the output in the studies was inconclusive for the meta analysis. Only four of the studies used the same software while the other six employed different software. It is known that the software used in the imaging will reflect the final image, as it is used for the image editing, resolutions, margins, reconstructions, color saturations, etc. In our review, the data regarding the artifacts was not available. When compared to the conventional panoramic view, the new CBCT has shown lesser artifacts and human errors. Furthermore, in the new CBCT and the microcomputed CT, three dimensional constructions are available. There was no uniformity regarding the specialist inferring to the image output. In two of the present studies were oral radiologists, while in four, they were endodontists. The chief limitation in our study was our inconclusiveness with the evaluation of root canal morphology and the factors affecting it, as there were many discrepancies in the study methods. Furthermore, it was not possible to compare the various types of teeth like incisors vs. molars, single-rooted vs. multirooted teeth, incidence of the second canal in the mesiobuccaal root of the maxillary molars,[25] etc. We propose that CBCT and the microcomputed CT have to be further studied in vivo and in the general dentist practice also.

CONCLUSION

The results from the current systemic review conclude that the CBCT and the microcomputed tomography are comparable, nonetheless with few exemptions of the in-depth anatomical variations and presentations of the permanent teeth.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.