Cone-Beam Computed Tomographic Evaluation of Canal Morphology of Mesiobuccal Root of Maxillary Molars in Saudi Subpopulation.

Introduction: The purpose of this study was to analyze the canal configuration of mesiobuccal root (MBR) of the maxillary molars in the Saudi subpopulation using cone-beam computed tomography (CBCT) and to compare if there is any gender and arch variation. Methodology: In this cross-sectional retrospective evaluation study, analysis of CBCT scans of MBRs of 400 maxillary first and second molars was done that has undergone CBCT scanning for diagnostic/treatment purposes in the private clinic of Jeddah, KSA. Statistical analysis was performed using Student's t-test and Chi-square test.
Results: Type I, II, and III canal configurations have been reported to be the most common morphologies in the MBR in both first and second molars, with the incidence of 20.25% (81), 17.25% (69), and 17.25% (69), respectively. Type I canals were significantly (P < 0.001) more common in tooth #17 and #27, Type II canals were significantly (P < 0.001) more seen in tooth #26, Type 3 canals were more seen in tooth #27, but there is no statistically significant association. Supplemental canal configurations which were classified by Gulabivala as Type I, Type II, and Type IV were also seen. Furthermore, 93 additional unclassified canal configurations were also found.
Conclusion: The data indicate high prevalence of MB2 canals with varying canal configurations. Preoperative CBCT imaging should always be done in tooth-like maxillary molars, to understand the complex configurations and variations and to achieve higher success while performing root canal treatment. Copyright:

INTRODUCTION

The proper diagnosis followed by appropriate cleaning and shaping and three dimensional obturation of the root canal system is must to increase the root canal treatment outcome,[123] and thus to achieve this, it is necessary for the operator to have adequate knowledge of the internal anatomy and its variations of each tooth being treated.[1] Maxillary molars are the most commonly treated teeth,[123] and have the highest frequency of failures because of missed second mesiobuccal (MB2) canals.[3] Although not always located,[1234] but the incidence of the MB2 canal has been reported to be as high as 95%.[1]

In fact, in general, the most anatomically complex tooth is maxillary molar, and since 1925, especially the mesiobuccal root (MBR) have demonstrated numerous variations and complex morphologies,[4] and therefore, as compared to any other tooth, maximum research and the clinical investigation was done on the MBR of maxillary molars,[1] to look at the presence of the MB2 canal and its variations in maxillary molars.[3] Since then, in various regions of the world, MBR of maxillary molars has been studied.[1]

Compared to other tooth, the high failure rate of root canal treatment of maxillary molars indicate that more studies and researches are required to acquire more knowledge and understanding related to the anatomy of root canal systems and canal configurations, especially of MBR.[1] Thus, the purpose of this study was to analyze the canal configuration of MBR of the maxillary molars in the Saudi subpopulation using cone-beam computed tomography (CBCT) and to compare if there is any gender and arch variation.

METHODOLOGY

In this cross-sectional retrospective evaluation study, after obtaining ethical clearance from Batterjee Medical College, Jeddah (KSA), analysis of CBCT scans of MBR of maxillary molars in patient was done, that has undergone CBCT scanning for diagnostic/treatment purposes in the private clinic of Jeddah, KSA. Only first and second maxillary molars with complete root end development were included in this study. All third molars were excluded, and first and second molars, which are grossly decayed, root canal treated, having deep restorations, and crowns were also excluded. The number of canal/s and the canal configurations was examined and classified according to Vertucci's classification.[567]

All the data were tabulated and statistical evaluation was done using SPSS version 23.0. (SPSS Inc., Chicago, IL, USA). Descriptive statistics were used to calculate frequency and percentage. Comparison for mean values of variables was made using Student's t-test based on the normality of data. The association of categorical variables was done using Pearson's Chi-square test (P < 0.05 was considered statistically significant).

RESULTS

The study sample comprises 400 teeth, out of which 232 (58%) teeth are of female patients, and 168 (42%) teeth are of male patients. The mean age of participants was 28.07 years (standard deviation 12.44). In this study, total 96 (24%) tooth #16, 105 (26.3%) tooth #17, 101 (25.3%) tooth #26, and 98 (24.5%) tooth #27 were examined. When we assessed the prevalence of the type of canals in MBR of different teeth, it was found that Type I canals were significantly (P < 0.001) more common in tooth #17 and #27, Type II canals were significantly (P < 0.001) more seen in tooth #26, Type 3 canals were more seen in tooth #27, but there is no statistically significant association, Type 4 canals were significantly (P < 0.001) less common in tooth #27, Type 5 canals were significantly (P < 0.001) more common in tooth #16 and #17, Type 6 canals were significantly (P < 0.001) more common in Tooth #16, and Type VII canal configuration is seen only once in tooth #27 [Table 1 and Graph 1]. Supplemental canal configurations like: 3-1, 3-2, and 2-1-2-1, which were not classified by Vertucci, but were classified by Gulabivala as Type I (G Type I), Type II (G Type II), and Type IV (G Type IV) respectively,[5] were also seen in MBR of maxillary molars. “G Type I” canal is seen only once in tooth #26, and “G Type II” canal is seen only twice in tooth #16. Whereas “G Type IV” canals were significantly (P < 0.001) more commonly seen in tooth #16 and #26. Apart from these supplemental canal configurations, we found 93 additional canal configurations [Table 1 and Graph 1], like 1-2-3, 2-3-2, 3-2-3, 3-2-1, etc., which were neither classified by Vertucci nor by Gulabivala and therefore, we club all these additional canal configurations as “Unclassified canal configurations (UCC).” These UCC are seen in the MBR of all four molars, and there is no significant association with any of them. Furthermore, we did not find any significant association of the type of canals with the gender (P = 0.860) [Table 2 and Graph 2], and the location (P = 0.166) [Table 3 and Graph 3].

Table 1

Relationship between type of tooth and type of canals

Classification	Tooth number				Total	χ 2	P
	16.00, n (%)	17.00, n (%)	26.00, n (%)	27.00, n (%)
Type I	5 (6.2)	33 (40.7)	9 (11.1)	34 (42.0)	81 (100.0)	83.231	<0.001
Type II	13 (18.8)	21 (30.4)	22 (31.9)	13 (18.8)	69 (100.0)
Type III	15 (21.7)	18 (26.1)	16 (23.2)	20 (29.0)	69 (100.0)
Type IV	9 (34.6)	5 (19.2)	10 (38.5)	2 (7.7)	26 (100.0)
Type V	9 (40.9)	9 (40.9)	1 (4.5)	3 (13.6)	22 (100.0)
Type VI	6 (42.9)	1 (7.1)	5 (35.7)	2 (14.3)	14 (100.0)
Type VII	0	0	0	1 (100.0)	1 (100.0)
G Type I	0	0	1 (100.0)	0	1 (100.0)
G Type II	2 (100.0)	0	0	0	2 (100.0)
G Type IV	6 (27.3)	5 (22.7)	7 (31.8)	4 (18.2)	22 (100.0)
UCC	31 (33.3)	13 (14.0)	30 (32.3)	19 (20.4)	93 (100.0)
Total	96 (24.0)	105 (26.3)	101 (25.3)	98 (24.5)	400 (100.0)

UCC: Unclassified canal configurations

Graph 1

Relationship between the type of tooth and type of canals

Table 2

Relationship of gender and type of canals

Classification	Gender		Total, n (%)	χ 2	P
	Female, n (%)	Male, n (%)
Type 1	51 (63.0)	30 (37.0)	81 (100.0)	83.231	<0.001
Type 2	38 (55.1)	31 (44.9)	69 (100.0)
Type 3	40 (58.0)	29 (42.0)	69 (100.0)
Type 4	15 (57.7)	11 (42.3)	26 (100.0)
Type 5	15 (68.2)	7 (31.8)	22 (100.0)
Type 6	8 (57.1)	6 (42.9)	14 (100.0)
Type 7	0	1 (100.0)	1 (100.0)
G Type I	0	1 (100.0)	1 (100.0)
G Type II	1 (50.0)	1 (50.0)	2 (100.0)
G Type IV	11 (50.0)	11 (50.0)	22 (100.0)
UCC	53 (51)	40 (30)	93 (81)
Total	232 (58.0)	168 (42.0)	400 (100.0)

UCC: Unclassified canal configurations

Graph 2

Relationship of gender and type of canals

Table 3

Relationship of location (side) and type of canals

Classification	Side of jaw		Total, n (%)	χ 2	P
	Left, n (%)	Right, n (%)
Type 1	43 (53.1)	38 (46.9)	81 (100.0)	14.150	0.166
Type 2	36 (52.2)	33 (47.8)	69 (100.0)
Type 3	36 (52.2)	33 (47.8)	69 (100.0)
Type 4	12 (46.2)	14 (53.8)	26 (100.0)
Type 5	4 (18.2)	18 (81.8)	22 (100.0)
Type 6	7 (50.0)	7 (50.0)	14 (100.0)
Type 7	1 (100.0)	0	1 (100.0)
G Type I	1 (100.0)	0	1 (100.0)
G Type II	0	2 (100.0)	2 (100.0)
G Type IV	11 (50.0)	11 (50.0)	22 (100.0)
UCC	50 (53.8)	43 (46.2)	93 (100.0)
Total	201 (50.2)	199 (49.8)	400 (100.0)

UCC: Unclassified canal configurations

Graph 3

Relationship of location (side) and type of canals

DISCUSSION

The anatomy of the root canal of any particular teeth not only has certain common characteristics but also has various atypical ones, and if the operator takes necessary actions, it will lead to successful endodontic treatment.[1] However, because of the extremely complex anatomy of MBR, it is a big challenge to perform successful root canal treatment on maxillary molars,[89101112] and therefore, various approaches have been suggested to identify the canal variations and complexities, such as acquiring anatomical familiarity by gaining knowledge regarding canal configurations and variations in different races and ethnic groups,[13] using the CBCT (before or during the treatment), dental operating microscope (DOM), stains, and troughing with ultrasonic.[9] In our study, we have used CBCT to study the complexities and variations of MBR, as the use of CBCT is recommended in cases with unexpected complex anatomy and with “difficult to locate” canals.[14]

In the current study, Type I, II, and III canal configurations have been reported to be the most common morphologies in the MBR in both first and second molars, with the incidence of 20.25% (81), 17.25% (69), and 17.25% (69), respectively. In this study, 6.2% (5) of the tooth #16, and 11.1% (9) of the tooth #26 has Type I canal configuration in MBR, although no statistically significant difference was found between them [Table 1 and Graph 1]. Hence, this means 95% (91) of the tooth #16, and 91% (92) of the tooth #26 has more than one canal in MBR. Our results are different from various other studies which were conducted in different parts of the world using CBCT, where the prevalence of MB2 was found to be 80% in the UAE,[9] 71% in the Portuguese population,[15] 55.6% in the Saudi population,[2] 40.3% in the Italian population,[16] 72.8% in the Egyptian population,[17] 68.2% in the American population,[18] 70.2% in the Iranian population,[19] 64.6% in the Korean population,[20] and 52% in the Chinese subpopulation.[21] However, our results are close to the findings of the studies done by Pérez-Heredia et al.[22] and Reis et al.,[23] where the prevalence of the second canal in MBR was found to be 86.2% among the Spanish population,[22] and 88.5% among the Brazilian population,[23] respectively. As compared to other studies, in our study, we found high prevalence of second canals in MBR. This increased identification maybe because of the experience of the individuals reading the CBCT, the sample of teeth, the interpretation of the CBCT, or the advancements in CBCT technology.[4]

In this study, 40.7% (33) of the tooth #17, and 42% (34) of the tooth #27 has Type I canal configuration, which is significantly higher (P < 0.001) than the tooth #16 and tooth #26 [Table 1 and Graph 1]. Our findings are in accordance with the study done by Naseri et al.,[24] where Type I canal configuration in maxillary second molar, was found in 31% of cases.

In the present study, Type II canal configuration is significantly higher (P < 0.001) in tooth #26, as compared to tooth #16, #17, and #27, Type IV canal configuration is significantly lower (P < 0.001) in tooth #27, Type V canal configuration is significantly higher (P < 0.001) in tooth #16 and #17, and Type VI canal configuration is significantly higher (P < 0.001) in tooth #16, indicating that there are high chances of finding unexpected complex anatomy and variation in the canals of MBR [Table 1 and Graph 1].

Variations in canal configurations with relation to gender should always be considered.[2] However, in our study, no statistically significant difference was found on comparing the type of canal configuration of MBR with the gender [Table 2 and Graph 2]. This finding is in accordance with the study done by Al-Nazhan[25] and Zhang et al.,[21] where they both found no significant relationship between the gender and number of canals. However, this finding is not in accordance with the study done by Fogel et al.,[26] Kim et al.,[20] Al-Shehri et al.,[2] and Naseri et al.,[24] where a significantly higher number of canals were found in males as compared to females. This difference might be because of the sample size, ethnic difference, the interpretation of the CBCT, or the advancements in CBCT technology. No statistically significant difference was found on comparing the type of canal configuration of MBR with the location of the tooth (side of the jaw) [Table 3 and Graph 3]. Thus indicating that the prevalence of canal configurations and variations are the same on both sides of the jaw. In current study, 23.25% (93) teeth were found with additional UCC (1-2-3, 2-3-2, 3-2-3, 3-2-1, etc.) which are not reported before. Prevalence of UCC is 33.3% (31) in tooth#16, 32.3% (30) in tooth#26, 14% (13) in tooth#17, and 20.4% (19) in tooth#27; however, no statistically significant difference is found in the number of cases and the type of tooth.

CONCLUSION

Within the limitations of this study, we found that most maxillary first and second molars had complex canal configurations. While performing root canal treatment of maxillary molars, the operator should always consider that there are two canals in the MBR until proven differently. Many studies and case reports have shown that DOM is very useful for detecting two or more MBR canals in maxillary molars. CBCT is of great help for clinicians to understand the variations and complex morphology of MBR and to achieve higher success in root canal treatment of maxillary molars. Hence, the data which are obtained from this study, possibly suggest that the routine use of preoperative small field of view CBCT imaging may be recommended preoperatively for root canal treatment of maxillary molars. Further studies with larger sample sizes are recommended for the generalization of results.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.