Prevalence and Complexity of Middle Mesial Canal in Mandibular First Permanent Molars of a Turkish Subpopulation

1. Introduction

The biological success of root canal treatment (RCT) depends not only on effective chemomechanical shaping and disinfection, but also on accurate identification and treatment of the entire root canal system.¹ In mandibular molars, the complex anatomy of the mesial root, characterized by accessory canals, intercanal communications, and narrow fin/isthmus structures, creates a morphological spectrum that is particularly prone to being overlooked during diagnosis and treatment.^2,3 In this context, evidence indicating that untreated or missed canals may be associated with post-treatment apical pathology further underscores the clinical importance of comprehensive canal anatomy assessment.

Although the mesial root of the mandibular first molar (MFM) classically contains 2 main canals, the mesiobuccal (MB) and mesiolingual (ML) canals, additional canal lumens or intercanal communication variants may occur between them. This anatomical structure has been described in the literature as the middle mesial canal (MMC) and has been emphasized as a clinically relevant variation that warrants particular attention during treatment of the mesial root.⁴ One key aspect underlying the clinical significance of the MMC is that it does not invariably present as a fully independent third canal; instead, it may appear as a pathway that merges with or communicates with the main canals, or as fin-like morphologies.^2,4 Therefore, MMC detection should not be approached solely as a search for an additional orifice, but rather requires an assessment strategy that accounts for the 3D canal architecture of the mesial root.⁵

MMC prevalence has been reported across a wide range in the literature, largely depending on the detection method employed and on how broadly the term “MMC” is defined.⁶ Clinically, higher detection rates have been demonstrated when MMCs are actively sought under a dental operating microscope using targeted exploration and troughing procedures, indicating that identification is highly sensitive to the quality of visualization and exploration.⁷ Conversely, µCT-based morphological investigations have enabled detailed characterization of fine intercanal communications and confluent configurations within the mesial root, providing high-resolution data on both prevalence and morphology. Indeed, µCT studies conducted across different populations have described the anatomical diversity of MMCs in considerable detail.²

Recent CBCT-based evidence indicates that reported MMC prevalence is shaped by both geographic variation and methodological heterogeneity. A systematic review and meta-analysis⁸ estimated a pooled global MMC prevalence of approximately 4.4% in MFMs. A multinational CBCT study with meta-analysis further demonstrated between-country/ethnicity differences.⁹ In addition, individual CBCT studies^10,11 have reported substantially higher prevalences in Turkish populations, such as 15.58%⁹ and 24.5%, highlighting the impact of population-specific factors and protocol-related differences including voxel size and field of view. While CBCT enables three-dimensional assessment of complex canal anatomy, its diagnostic yield in morphological studies is directly dependent on acquisition protocol standardization and image-quality criteria, including voxel size and field of view.¹²

Although literature has established the presence and morphological diversity of MMCs, CBCT-derived prevalence estimates can vary across populations and imaging protocols, and morphological data describing MMC relationships with the main canals remain clinically relevant for decision-making. In this context, evaluating CBCT archives acquired with standardized protocols in populations such as Türkiye may improve prediction of expected MMC frequency and facilitate

clinically meaningful interpretation of MMC configurations. Accordingly, this study aimed to determine MMC prevalence in MFMs using CBCT archive data, classify MMC configurations according to the Pomeranz system, and characterize confluence/communication patterns with the main mesial canals. A secondary aim was to assess associations with sex and tooth side to support clinical interpretation and inform future hypothesis-driven research.

2. Materials and Methods

2.1. Study Design and Data Source

The study was approved by the Institutional Ethics Committee of Akdeniz University Faculty of Dentistry (Protocol No: TBAEK-829, Date: August 28, 2025) and conducted in accordance with the Declaration of Helsinki. The requirement for informed consent was waived due to the retrospective nature of the study. This retrospective cross-sectional study was based on an archive review of CBCT examinations acquired at Akdeniz University Faculty of Dentistry between February 3, 2020, and December 5, 2025, using routine clinical protocols. For case identification, the institutional CBCT archive was first filtered to examinations in which the mandibular molar region was included within the field of view (FOV); within this subset, scans were subsequently screened for eligibility according to prespecified inclusion and exclusion criteria. The unit of analysis was the tooth, and mandibular first molars (FDI 36 and 46) were evaluated on a tooth-based basis. Because the CBCT protocol employed a limited field of view of 40.08 × 40.08 × 40.32 mm centered on a single mandibular molar, each examination volume contained only one eligible tooth. Consequently, each tooth in the dataset corresponds to a unique patient, and intra-patient clustering does not apply to this study.

2.2. Sample Size Calculation

Sample size was estimated a priori using a one-sample proportion formula. Based on Turkish-population estimates from µCT² (14.8%), Solakoğlu & Kurt’s CBCT-based study¹¹ (24.5%), and considering that West Asian populations show higher MMC prevalence than the global CBCT-pooled⁶ estimate of 4.15%, an expected prevalence of 15% was adopted as a conservative planning estimate. A minimum sample of 1.110 MFMs was required to estimate prevalence within ±2.1 percentage points with 95% confidence (two-sided α = 0.05). The final sample of 1.175 MFMs exceeded this threshold.

2.3. CBCT Acquisition Parameters

All CBCT scans were acquired by the same radiographic technician using a Veraview X800 unit (J. Morita, Kyoto, Japan) with a limited field-of-view protocol (FOV: 40.08 × 40.08 × 40.32 mm) and an isotropic voxel size of 0.08 mm. Exposure parameters were standardized at 100 kV and 4.8 mA with a scan time of 17.9 s (360° rotation; 2π), using a 0.2-mm copper filter.

2.4. Inclusion and Exclusion Criteria

Eligibility was determined by using prespecified inclusion and exclusion criteria. CBCT volumes were included if they contained MFMs with complete root development and provided diagnostic resolution sufficient for assessment of canal anatomy, with adequate image quality and minimal motion or metal artifacts. Scans were excluded when motion or metal artifacts compromised diagnostic interpretation, or when root fracture, advanced root resorption, or extensive periapical lesions distorted normal canal anatomy. Teeth with evidence of previous RCT were also excluded, as were images of insufficient quality to allow reliable anatomical assessment.

2.5. MMC Definition and Classification

The presence of an MMC was defined as visualization of an additional canal lumen on CBCT slices located between the MB and ML canals within the mesial root (Fig. 1). In teeth with an identified MMC, canal configuration was recorded according to the Pomeranz classification⁴ as P1 independent, P2 confluent, or P3 fin. For P2 and P3 cases, the side of MMC confluence or communication with either the MB or ML canal was additionally recorded as the confluence site (Fig. 2).

2.6. Image Assessment and Data Collection

Before image review, a structured data collection table was created to standardize variable recording. For each eligible CBCT examination, a unique study identifier was assigned, and the tooth number (FDI 36 or 46) and patient sex were recorded from the institutional archive.

CBCT volumes were analyzed using One Volume Viewer software (J. Morita, Kyoto, Japan) for multiplanar reconstruction and 3D Slicer (version 5.10, open-source; https://www.slicer.org) for three-dimensional rendering and supplementary spatial orientation. Images were reviewed simultaneously in axial, coronal, and sagittal planes at the native isotropic voxel resolution of 0.08 mm, without additional interpolation or slice-thickness modification. Assessment was conducted primarily in the axial (horizontal) plane, with systematic slice-by-slice navigation from the pulp chamber floor in an apical direction through the full length of the mesial root. Coronal and sagittal reconstructions were used as complementary views to confirm canal position and spatial relationships when needed.

Image assessment comprised two independent readings. Two endodontists, each with at least 5 years of clinical experience, jointly reviewed all CBCT volumes and recorded a single consensus reading per tooth. Independently and blinded to this reading, an oral and maxillofacial radiologist evaluated all volumes in a separate session. Both readings recorded MMC presence/absence and, when present, the Pomeranz configuration and the MB/ML confluence site. Agreement between the endodontic consensus reading and the independent radiologic reading was quantified with Cohen's κ. Discrepancies between the two readings were resolved by a senior endodontist (professorial rank, 27 years of clinical experience) to establish the final dataset.

2.7. Statistical Analysis

Data was analyzed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). Categorical variables were summarized as counts and percentages, and MMC prevalence was reported with 95% confidence intervals (Wilson score method). Group comparisons used the Pearson chi-square test; all expected cell frequencies exceeded 5, so no continuity correction was applied. Effect sizes for 2×2 comparisons were expressed as odds ratios (OR) with 95% CIs (Woolf method). The association between MMC presence and sex and tooth side was further examined by binary logistic regression; model fit was assessed using the likelihood-ratio chi-square, McFadden pseudo-R², and Nagelkerke R². To control the familywise Type I error rate, Bonferroni correction was applied across six pre-specified simultaneous comparisons (adjusted α = 0.0083). These six comparisons comprised: (1) MMC prevalence by sex, (2) MMC prevalence by tooth side, (3) Pomeranz-type distribution by sex, (4) Pomeranz-type distribution by tooth side, (5) confluence site by sex, and (6) confluence site by tooth side. All six tests addressed the same overarching research question regarding the influence of patient sex and tooth side on MMC-related outcomes and were therefore treated as a single family of comparisons for correction purposes; both uncorrected and Bonferroni-adjusted p-values are reported. Post-hoc power for the two primary comparisons was calculated using the two-proportion z-test with Cohen's h (small: <0.20, medium: 0.20-0.50, large: >0.50). Statistical significance was set at p<0.05.

3. Results

A total of 1175 MFMs were evaluated (tooth 36: n = 617; tooth 46: n = 558). Of these, 613 teeth (52.2%) belonged to male patients and 562 (47.8%) to female patients (Table 1). Agreement between the endodontists' consensus reading and the independent radiologic reading was excellent (Cohen's κ = 0.892; 96.9% agreement; 95% CI 0.862–0.922); discrepant cases were adjudicated by a senior endodontist. Cases in which the 2 primary observers disagreed were resolved by a third senior endodontist with professorial rank.

An MMC was identified in 118 of 1.175 teeth, yielding an overall prevalence of 10.04% (95% CI: 8.45-11.89). By sex, MMC prevalence was 11.09% in males (68/613; 95% CI: 8.85-13.83) and 8.90% in females (50/562; 95% CI: 6.81-11.54), with no statistically significant difference (χ²=1.565, p = 0.211; OR = 1.28, 95% CI: 0.87-1.88). On a tooth-based comparison, MMC prevalence was 8.10% for tooth 36 (50/617; 95% CI: 6.20-10.53) and 12.19% for tooth 46 (68/558; 95% CI: 9.73-15.16). Tooth 46 showed a nominally higher MMC prevalence than tooth 36 (χ²=5.406, p=0.020; OR=1.57, 95% CI: 1.07-2.31); however, this difference did not meet the adjusted significance threshold after Bonferroni correction for 6 concurrent comparisons (p_adjusted = 0.120; α_Bonferroni=0.0083) (Table 1).

Among the 118 MMC-positive teeth, the most frequent configuration was P2 (confluent) (55/118, 46.6%), followed by P3 (fin) (35/118, 29.7%) and P1 (independent) (28/118, 23.7%). The distribution of Pomeranz types did not differ significantly by sex (χ² = 0.276, df = 2, p = 0.871) or by tooth side (χ² = 0.875, df = 2, p = 0.646), and these findings remained unchanged after Bonferroni correction (Table 2).

In the subset of 90 cases comprising P2 and P3 types, the confluence site of the MMC with the main canals was evaluated. Confluence with the ML and MB canals occurred at identical rates (ML: 45/90, 50%; MB: 45/90, 50%). The distribution of confluence site did not differ significantly by sex (χ² = 1.131, p = 0.288) or by tooth side (χ² = 0.741, p = 0.389), and these results also remained unchanged after Bonferroni correction (Table 2).

In the logistic regression model including sex and tooth type simultaneously, tooth 46 was associated with 1.58-fold higher odds of MMC presence compared with tooth 36 (OR = 1.58, 95% CI: 1.07-2.31; p = 0.021). Sex did not reach statistical significance (OR = 1.28, 95% CI: 0.87-1.88; p = 0.210). Although the overall model was statistically significant, the explained variance was low (Nagelkerke R² = 0.012), suggesting that MMC presence may be influenced by factors beyond tooth type and sex (Table 3).

4. Discussion

The overall MMC prevalence of 10.04% observed in this high-resolution CBCT cohort indicates that approximately 1 in 10 MFMs harbor a MMC, a frequency with direct clinical relevance during RCT planning. No significant sex-related difference was detected. Tooth 46 showed nominally higher prevalence than tooth 36, though this did not survive Bonferroni correction. The predominant morphology was confluent (P2, 46.6%), and confluence with the MB and ML canals was equally distributed (50% each). Collectively, these findings suggest that MMCs in mandibular molars most often occur as variants connected to the main canals and may be readily overlooked in clinical practice.

Although CBCT-adapted systems have been proposed to further distinguish MB-confluent from ML-confluent configurations¹³, the Pomeranz classification was retained to maximize comparability with the broader MMC literature, in which this system remains most widely applied. The directional confluence site was recorded as a separate variable, thereby capturing the clinically relevant distinction provided by CBCT-specific systems without departing from the established classification framework.

Our findings show both concordance and divergence with MMC prevalence rates reported in the literature. Overall, CBCT-based studies tend to report lower MMC prevalence. For example, prevalences in the range of approximately 1-5% have been reported in Chinese¹⁴ (2.7%), Korean¹⁵ (0.35%), Iranian¹⁶ (3.1%), and Saudi Arabian¹⁷ (1.3%) populations. In contrast, studies using clinical exploration or µCT have

reported substantially higher MMC frequencies. For instance, Nosrat et al.⁷ observed MMCs in approximately one-fifth of mandibular first and second molars. Likewise, Azim et al.¹⁸ reported an even higher incidence in mandibular molars when MMCs were actively searched for after troughing under a dental operating microscope, highlighting how detection rates increase with enhanced visualization and targeted exploration. Recent meta-analyses⁶ restricted to MFMs have estimated a global MMC prevalence of approximately 4.15% and have further indicated that geographic variability may be an important determinant. Taken together, the approximately 10% prevalence observed in the present study — higher than the pooled global CBCT estimate of ~4.15% — likely reflects a confluence of factors rather than any single determinant, including the high spatial resolution of our 0.08-mm voxel protocol, which may have enhanced detectability of small canal lumens. Beyond imaging protocol, differences in MMC case definitions, inconsistencies in observer training and classification criteria, and variation in inclusion and exclusion criteria across study populations may each independently influence reported prevalence estimates. Population-specific anatomical characteristics may also contribute, but their independent effect cannot be reliably disentangled from these methodological sources of heterogeneity in the existing literature. Accordingly, cross-study prevalence comparisons should be interpreted with caution, and the approximately 10% prevalence observed in the present study should be contextualized within the specific methodological framework employed rather than treated as a definitive population-level estimate.¹⁹

Of particular relevance is the comparison with Solakoğlu & Kurt¹¹ who reported a substantially higher MMC prevalence of 24.5% in a Turkish population using a larger sample (n = 2.999). The discrepancy between their findings and ours likely reflects methodological

differences rather than true population heterogeneity. Paradoxically, higher-resolution imaging may yield more conservative prevalence estimates when stricter visualization criteria are applied to borderline canal configurations; the voxel size in that study was 0.20 mm compared with 0.08 mm in the present study. Additionally, differences in MMC case definition and classification systems between studies may contribute to this divergence. Taken together, these observations underscore that even within the same geographic population, MMC prevalence estimates are sensitive to imaging protocol and definitional criteria.

The absence of a significant sex-related difference suggests that MMC morphology may be driven more by genetic and structural determinants than by biological sex. Consistent with this interpretation, the literature has not demonstrated a reproducible association between MMC presence and sex. However, our post hoc power analysis indicated limited power for the sex comparison (24.1%), which constrains the statistical certainty of this null finding.

With respect to side, MMC prevalence was nominally higher in tooth 46, with an odds ratio of approximately 1.6 and a p value of 0.021, but this association did not remain significant after Bonferroni adjustment. In the multivariable model, tooth 46 remained associated with higher odds of MMC presence (58% increased odds; p = 0.021), yet the model's explained variance was low, as discussed below. Overall, the influence of sex and side on MMC presence appears clinically modest in our dataset, as reflected by the negligible to small effect sizes across all comparisons (φ=0.037–0.068). The lack of robust statistical significance after correction, together with limited power for the sex comparison, warrants cautious interpretation. The very low explained variance of the logistic regression model (Nagelkerke R² = 0.012) reflects the inherent complexity of MMC occurrence and should be interpreted in the context of the model's deliberately restricted scope. The model was designed as a descriptive tool to quantify the independent associations of sex and tooth side -two routinely available clinical variables- rather than as a predictive instrument intended to explain the full variability in MMC presence. As such, the low R² value is not unexpected and does not invalidate the reported associations; rather, it underscores that sex and tooth side alone are insufficient predictors of MMC occurrence. Candidate determinants of the unexplained variability include root morphological features such as root curvature, mesiodistal root width, and inter-orifice distance, as well as patient-level factors including age and genetic background, none of which were captured in the present retrospective dataset. Future studies incorporating these variables in multivariable models are needed to develop a more comprehensive explanatory framework for MMC occurrence.

In teeth in which an MMC was detected, canal morphology was predominantly confluent. The P2 configuration (46.6%) was markedly more common than the P1 independent configuration (23.7%), suggesting that the MMC often does not present as a clearly separate orifice coronally but rather represents a canal pathway that merges with the MB or ML canal in the apical portion of the root. This pattern is consistent with µCT evidence. Versiani et al.² reported that confluent configurations accounted for 83.3% of MMCs in Brazilian and Turkish samples, whereas truly independent MMCs were uncommon at 6.3%. In our cohort, the P3 fin type was also frequent, occurring in approximately 30% of MMC-positive teeth.

The absence of differences in Pomeranz-type distribution by sex or tooth side further suggests that MMC morphology reflects a tooth-specific anatomical pattern rather than patient-related factors. Clinically, these findings underscore that MMC detection should not rely solely on the expectation of an independent third canal. Instead, the MB–ML intercanal region should be systematically evaluated for fin-like and fusion-related variants, with active consideration of intercanal communications during exploration and cleaning.

We observed a perfectly symmetric distribution of MMC confluence with the main canals, with equal rates of merging into the ML and MB canals (50% vs 50%). Many previous reports have suggested a tendency for MMCs to join the MB canal more frequently; for example, Versiani et al.² found that most confluent MMCs terminated in the MB canal. In contrast, our data indicate no preferential confluence pathway along the MB-ML continuum. From a clinical perspective, this finding highlights that canal exploration should not be biased toward a single direction. During troughing and inspection of the developmental groove, both the MB and ML aspects should be evaluated with equal attention, as unilateral expectations such as assuming that MMCs typically join the MB canal may increase the risk of missing relevant anatomy. Overall, our results encourage clinicians to anticipate potential MMC communications with either main canal. The discrepancy between our findings and previous reports may partly reflect methodological differences. In the present study, confluence site was recorded as a supplementary binary variable rather than as the primary classification criterion, and the relatively modest number of eligible cases (n = 90) limits the precision of this estimate. Furthermore, the Pomeranz system does not distinguish MB-confluent from ML-confluent subtypes as its primary output; studies employing the Barros-Costa classification, which is specifically designed for this distinction, have reported MB-confluent predominance more consistently.¹³ This finding warrants replication in larger samples using CBCT-based classification systems in which confluence direction is treated as a primary outcome variable.

Missing an MMC may contribute to endodontic failure.²⁰ Accordingly, during access cavity preparation in MFMs, the developmental groove between the MB and ML canals should be carefully explored, and visualization should be optimized using adjuncts such as a dental operating microscope and ultrasonic tips to enhance illumination and troughing control.²¹ The detection of fine canal anatomy may be further supported by the use of dyes or sodium hypochlorite bubbling “champagne” tests.²² However, because the MMC is frequently confluent with the main canals, excessive dentin removal should be avoided to minimize the risk of strip perforation along the mesial wall. In practical terms, the MMC should be approached with the same level of meticulousness typically applied when searching for a second MB canal in maxillary molars.⁶ The approximately 10% prevalence observed in our study implies that an MMC may be present in roughly one out of every ten MFMs, underscoring the importance of routinely considering this anatomy during clinical assessment and treatment.

The present study did not incorporate inter-orifice distance (IOD) measurements between the MB and ML canal orifices, nor was patient age recorded as a study variable. Emerging evidence suggests that wider MB–ML IOD may be associated with a higher likelihood of MMC occurrence, with independent-type (P1) MMCs showing larger IOD values compared with confluent and fin configurations, and that secondary dentin deposition related to advancing age may progressively reduce canal lumen detectability, particularly for fine or confluent variants. Consistent with this, younger patients have been reported to show higher rates of confluent and fin MMC configurations. Accordingly, future studies should prospectively incorporate IOD measurements stratified by Pomeranz type and account for patient age, as these parameters may serve as clinically useful predictors and help explain residual variability not captured in prevalence-focused retrospective designs such as the present one.²³

Key strengths of this study include the large sample size (n = 1.175) and the use of a single CBCT unit with a standardized acquisition protocol for all examinations. The single-center, single-device design and the small isotropic voxel size (0.08 mm) enhanced data homogeneity and supported detailed anatomical assessment. Image interpretation was performed independently by 2 endodontists with at least 5-year of clinical experience and an experienced radiology specialist, and discrepancies were resolved through a structured consensus procedure, thereby strengthening the reliability of data collection. In addition, the systematic documentation of Pomeranz configurations and MMC confluence patterns provided a comprehensive morphological profile of MMC anatomy.

This study has limitations inherent to its retrospective, single-center design, which may restrict generalizability. Although high-resolution CBCT was used, CBCT remains less sensitive than µCT, and very fine canal structures may still be missed. Several potentially relevant variables were not captured in the present retrospective dataset, which limits the interpretability of the findings. Patient age was not recorded, precluding assessment of age-related secondary dentin deposition and its potential effect on canal lumen detectability. Root morphological characteristics — including root curvature, mesiodistal root width, inter-orifice distance between the MB and ML canals, and root rotation — were not evaluated, despite emerging evidence that these parameters may be associated with MMC occurrence. Tooth developmental stage beyond the criterion of complete root formation was also not assessed. The absence of these variables should be considered when interpreting the low explained variance of the logistic regression model and when extrapolating the findings to broader clinical or research contexts. The application of Bonferroni correction for multiple comparisons may have reduced statistical power and increased the likelihood of overlooking true differences.

5. Conclusion

In this large retrospective CBCT-based study of MFMs, the prevalence of a MMC was 10.04%. MMC occurrence did not differ significantly by sex, and although tooth 46 showed a nominally higher prevalence than tooth 36, this association was not robust after adjustment for multiple comparisons and explained only a small proportion of variability in multivariable analysis. Morphologically, in our study, MMCs were predominantly confluent, with P2 as the most frequent Pomeranz type, and confluence to the MB and ML canals occurred at equal rates. Collectively, these findings indicate that MMCs in MFMs are not rare and are most often connected to the main mesial canals, underscoring the need for systematic evaluation of the MB-ML developmental groove during RCT. Future prospective, multicenter studies incorporating additional anatomical and demographic predictors and, where feasible, clinical or µCT validation are warranted to further clarify determinants of MMC presence and morphology.

References

1. Costa FFNP, Pacheco-Yanes J, Siqueira JF, Oliveira ACS, Gazzaneo I, Amorim CA, et al. Association between missed canals and apical periodontitis. Int Endod J. 2019;52(4):400-406.
2. Versiani MA, Ordinola-Zapata R, Keleş A, Alcin H, Bramante CM, Pécora JD, et al. Middle mesial canals in mandibular first molars: a micro-CT study in different populations. Arch Oral Biol. 2016;61:130-137.
3. Ercan E, Rasat A, Değermenci M, Er K. Evaluation of the distance between the mandibular canal and mandibular teeth roots with cone beam computed tomography. Akd Dent J. 2024;3(3):135-140.
4. Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod. 1981;7(12):565-568.
5. Penukonda R, Pattar H, Nambiar P, Al-Haddad A. Middle mesial canal in mandibular first molar: a narrative review. Saudi Dent J. 2023;35(5):468-475.
6. Motamedi MRK, Amirzade-Iranaq MH, Ha WN. A systematic review and meta-analysis of the prevalence and global distribution of middle mesial canals in mandibular molars identified by CBCT. Clin Oral Investig. 2024;28(6):310.
7. Nosrat A, Deschenes RJ, Tordik PA, Hicks ML, Fouad AF. Middle mesial canals in mandibular molars: Incidence and related factors. J Endod. 2015;41(1):28-32.
8. Al-Maswary AA, Almadhoon HW, Elkhateb A, Hamdallah A, Halboub E. The global prevalence of middle mesial canal in mandibular first and second molars assessed by cone beam computed tomography: a systematic review and meta-analysis. J Endod. 2023;49(6):638-656.
9. Pertek Hatipoğlu F, Mağat G, Hatipoğlu Ö, et al. Assessment of the prevalence of middle mesial canal in mandibular first molar: a multinational cross-sectional study with meta-analysis. J Endod. 2023;49(5):549-558.
10. Ece Yüzer M, Kaya S. Evaluation of middle mesial canal prevalence and morphology in mandibular molars in a Turkish population by cone beam computed tomography (CBCT). J Dent Mater Tech. 2023;12(3):111-117.
11. Solakoğlu E, Kurt Ö. Prevalence and morphometric assessment of the middle mesial canal in mandibular first molars in a Turkish population: a CBCT study. Odontology. 2026, in press.
12. Patel S, Brown J, Semper M, Abella F, Mannocci F. European Society of Endodontology position statement: use of cone beam computed tomography in Endodontics. Int Endod J. 2019;52(12):1675-1678.
13. Barros-Costa M, Ferreira MD, Costa FF, Freitas DQ. Middle mesial root canals in mandibular molars: Prevalence and correlation to anatomical aspects based on CBCT imaging. Dentomaxillofac Radiol. 2022;51(8):20220156.
14. Wang Y, Zheng QH, Zhou XD, Tang L, Wang Q, Zheng G, et al. Evaluation of the root and canal morphology of mandibular first permanent molars in a western Chinese population by cone-beam computed tomography. J Endod. 2010;36(11):1786-1789.
15. Kim SY, Kim BS, Woo J, Kim Y. Morphology of mandibular first molars analyzed by cone-beam computed tomography in a Korean population: variations in the number of roots and canals. J Endod. 2013;39(12):1516-1521.
16. Hasheminia M, Razavian H, Khorrami L, Mosleh H, Mohamadi S. Prevalence of middle mesial canal in mandibular first molars using cone-beam computed tomography technique. Dent Res J (Isfahan). 2021;18:42.
17. Aldosimani MA, Althumairy RI, Alzahrani A, Aljarbou FA, Alkatheeri MS, AlGhizzi MA, et al. The mid-mesial canal prevalence in mandibular molars of a Saudi population: a cone-beam computed tomography study. Saudi Dent J. 2021;33(7):581-586.
18. Azim AA, Deutsch AS, Solomon CS. Prevalence of middle mesial canals in mandibular molars after guided troughing under high magnification: an in vivo investigation. J Endod. 2015;41(2):164-168.
19. Singh H, Sroa RB, Mann JS. Middle mesial canal incidence and morphology in mandibular first molars: a cone-beam computed tomography and micro-computed tomography evaluation. J Conserv Dent. 2024;27(9):897-901.
20. Baruwa AO, Martins JNR, Meirinhos J, Pereira B, Gouveia J, Quaresma SA, et al. The influence of missed canals on the prevalence of periapical lesions in endodontically treated teeth: a cross-sectional study. J Endod. 2020;46(1):34-39.
21. Prade AC, Mostardeiro RDT, Tibúrcio-Machado CDS, Morgental RD, Bier CAS. Detectability of middle mesial canal in mandibular molar after troughing using ultrasonics and magnification: an ex vivo study. Braz Dent J. 2019;30(3):227-231.
22. Mohammadi Z, Asgary S, Shalavi S, Abbott PV. A clinical update on the different methods to decrease the occurrence of missed root canals. Iran Endod J. 2016;11(3):208-213.
23. Rohilla S, Negi S, Makkar S, Gupta S. Assessment of the interorifice distance between middle mesial canal and mesiobuccal canal; and middle mesial canal and mesiolingual canal in permanent mandibular first molars in a North-Indian subpopulation: A retrospective cone-beam computed tomography analysis. Endodontology. 2025;37:263-269.