Analysis of root morphology and internal anatomy of 400 maxillary first premolars using cone-beam computed tomography in an Indian Dravidian subpopulation: An ex vivo study

Abstract

Background:

There have been numerous cone-beam computed tomography (CBCT) studies done over the years to analyze the canal configurations among various racial and ethnic population groups. Several of these studies have highlighted a certain consistency in the incidence of particular features within these population subsets.

Aim:

The study aimed to analyze the root morphology and canal configurations of the maxillary first premolar (Mx1PM) in the Indian Dravidian subpopulation using CBCT.

Setting and Design:

This study involved a retrospective analysis of 200 CBCT scans, which included 400 Mx1PM.

Methods:

The CBCT images were evaluated, and the number of roots and canal configurations was recorded as per the Vertucci's classification.

Statistical Analysis:

Variations in the number of roots and canal anatomies were statistically interpreted using the Chi-square test of association with the significance level set at P < 0.05.

Results:

Among the 400 Mx1PM studied, 116 (29%) teeth displayed single roots and 284 (71%) showed the presence of two roots. The single-rooted premolars revealed a varied canal configuration with a predominance of Vertucci's Type II configuration in around 53.4% of the Mx1PM. The two-rooted premolars revealed 100% Type I canal configuration.

Conclusion:

The Mx1PM studied predominantly showed the two-rooted morphology with independent canals in each root. There was no significant difference between the teeth on either side of the same arch. The CBCT is an excellent nondestructive modality that can help us study the internal anatomy of pulp space accurately.

INTRODUCTION

The ability of the clinician to completely debride and comprehensively obturate the entire root canal space is the basic premise of root canal therapy. Thorough knowledge and understanding of the root canal space and their variations are considered the norm to achieve predictable success. A failure on the part of the clinician to detect and debride adequately or seal one or more of the root canals could be the precursor to subsequent endodontic treatment failure.[1,2]

While studies on the internal anatomy of teeth have previously involved laborious techniques, the introduction of the cone-beam computed tomography (CBCT) has proved to be pathbreaking in terms of endodontic diagnosis and research. The CBCT is a technically superior method to study root canal anatomy in the clinical setting owing to the noninvasive way it evaluates the three-dimensional anatomy of the tooth.[3,4]

Several studies conducted among different racial and geographical population groups have demonstrated the increased prevalence of variations in the canal configurations of the maxillary premolars.[2,5,6,7] Despite the enigmatic presentation of root form and canal morphology in the case of maxillary first premolar (Mx1PM), very few studies have been conducted among Indian population groups concerning the same[8,9,10,11,12,13,14] [Table 1].

Table 1.

Litrature review summary of previous investigations in various population

Investigator, year	Method of study	Sample size	Population understudy	Results Number of roots (%)
Wolf et al., 2020[15]	Micro CT	115 (maxillary first premolars)	Swiss German	Two roots most predominant (70)
Liu et al., 2019[16]	Microscopic CT	324 (maxillary first premolars)	Chinese adolescents	Single root most predominant (72.22)
Maghfuri et al., 2019[17]	CBCT	100 (maxillary first premolars)	Saudi	Two roots most predominant (61)
Pan et al., 2019[18]	CBCT	208 CBCT images (304 first premolars +333 second premolars)	Malaysian	First premolar – Two roots most predominant (67.8)
				Second premolar – One root most predominant (91.9)
Saber et al., 2019[19]	CBCT	700 premolars	Egyptian	First premolar – 2 roots most predominant (53.1)
				Second premolar – One root most predominant (72.8)
Alqedairi et al., 2018[20]	CBCT	707 CBCT images (334 first premolars +318 second premolars)	Saudi	First premolar – 2 roots most predominant (75.1)
				Second premolar – One root most predominant (85.2)
Senan et al., 2018[21]	Clearing technique	250 maxillary first premolars	Yemenian	One root most predominant (54.8)
de Lima et al., 2019[22]	CBCT	999 CBCT images (496 first premolars +503 second premolars)	Brazilian	First premolar – One root most predominant (80.2)
Felsypremila et al., 2015[8]	CBCT	246 CBCT (418 first premolars +393 second premolars)	Indian subpopulation	First premolar – 2 roots more predominant (51.2)
				Second premolar – One root more predominant (90.6)
Jayasimha Raj and Mylswamy 2010[9]	Clearing technique	200 maxillary second premolars	Indian	Root number not specified
Neelakantan et al., 2011[10]	Modified root canal staining technique	350 maxillary first premolars +350 maxillary second premolars	Indian	First premolar – 2 roots more predominant (84)
				Second premolar – One root more predominant (86)
Gupta et al., 2015[11]	Clearing technique	250 maxillary first premolars	North Indian	Single rooted more predominant (53.6)
Karunakaran et al., 2020[12]	CBCT (in vitro)	589 maxillary first premolars	Indian	2 roots more predominant (55.35)
Dinakar et al., 2018[14]	Clearing technique	225 maxillary first premolars	South Indian	Single root – Most predominant (52.88)
Karunakaran et al., 2019[13]	Visual examination (root form only studied)	822 maxillary first premolars	Indo-Dravidian South Indian	Two roots more predominant (54.74)
The present study (2021)	CBCT (in vitro)	400 maxillary first premolars	South Indian Dravidian	Two roots more predominant (71)

CT: Computed tomography, CBCT: Cone-beam CT

The Indian population has an amalgamation of racial features and multiple ethnicities. American anthropologist Carleton Coon reported that “India is the easternmost outpost of the Caucasian racial region” and defined the Indid race that occupies the Indian subcontinent as beginning in the Khyber pass.[23,24] While the northern populations are deemed to be Indo-Aryans, the southern populations of India are called as Dravidian and present with their own unique and distinguishable traits.[25]

Interestingly, our literature review revealed that few studies have been conducted to study the root and canal anatomy of (Mx1PM) among the south Indian subpopulations of Dravidian descent.[8,12,14] In addition, to our knowledge, no CBCT study has been conducted to study the anatomy of Mx1PM among an Indian Dravidian subpopulation group till date.

Therefore, the current study aims to evaluate the number of roots and internal anatomy of the Mx1PM in an Indian Dravidian subpopulation employing CBCT as a diagnostic tool.

METHODS

This study was approved by the institutional ethics committee (Protocol no. 15106). The sample size was set at 400, which was calculated using the formula with 95% confidence level and 80% power with respect to P = 50.[5] CBCT records of 200 patients who were prescribed CBCT scans as an adjunctive diagnostic tool during routine dental treatment at the dental school were retrospectively reviewed. A total of 400 Mx1PM from these CBCT records were scrutinized.

Scans that showed intact, fully developed Mx1PM bilaterally were included, and teeth that were compromised by physiological or pathological processes or where the original root anatomy was not precise were excluded.

Radiologic evaluation

The CBCT images were selected from the database of the Planmeca Promax 3D mid unit imaging system (Planmeca Oy, Helsinki, Finland). The CBCT images were taken with operating parameters set at 5.6 mA, 90 kV, and 27 s exposure time for small FOV, 8 mA, 90 kV, and 12 s exposure time for medium FOV. Romexis Viewer software was used to analyze images on a 21-inch LCD Dell monitor with a resolution of 1024 × 768 pixels (Dell Computer Corporation, Round Rock, TX, USA). The saturation and brightness of the scans were adjusted by means of a processing tool in the software to ensure optimum visualization. The CBCT images were examined by two endodontists individually. Each scan was studied in the coronal, sagittal, and axial views. The images were scrolled from buccal to palatal, mesial to distal, and from CEJ to apex to evaluate the canal morphology [Figure 1].

Figure 1.

Cone-beam computed tomographic images showing Vertucci's Type II canal configuration in maxillary first premolar – (a) Axial section showing two orifices, (b) saggittal section showing two separate canals from the cementoenamel junction then joining into a single canal toward the apical third (c) coronal section showing the single-root premolar

The following details were documented and analyzed:

1. Tooth position relative to the side of the arch

2. Number of roots, categorized as per the guidelines stated by Pécora et al.[5]

3. Canal configuration, classified as per the Vertucci's criteria.

Statistical analysis

Statistical Product and Service solutions, version 20.0 (SPSS Inc., Chicago, IL, USA) was used. The differences and frequency in the root number and canal anatomy in accordance with the tooth position were statistically interpreted using the Chi-square test of association with a significance level set at P < 0.05. The inter-examiner agreement between the two endodontists was evaluated using the Cohen's Kappa test (ranging from 0 to 1, with the value of 0.81–0.99 indicating almost perfect agreement, as proposed by Viera and Garrett).[26]

RESULTS

Of the 400 Mx1PM, 116 teeth (29%) displayed single-root morphology, while 284 teeth (71%) showed the presence of two roots.

The study of the individual canal configurations in the two-rooted Mx1PM revealed a complete presentation of Vertucci's Type I in 100% both buccal and palatal roots.

Among the single-rooted Mx1PM, 53.4% of the teeth had Type II configuration, while 21.6% had Type IV configuration. Type I configuration was seen in 12.59% of the teeth. Types III and V configurations together were observed in 12.41% of the teeth [Table 2].

Table 2.

The Bilateral symmetry and root canal configuration in maxillary first premolar (n=400)

Number of roots	Number of teeth	Bilateral symmetry		P	Canal configuration (%)
					Right	Left		Type I	Type II	Type III	Type IV	Type V	Type VI	Type VII	Type VIII
One	116 (29)	59 (29.5)	57 (28.5)	0.18	15 (12.9)		62 (53.4)	7 (6.03)	24 (20.6)	8 (6.8)	-	-	-
Two	284 (71)	141 (70.5)	143 (71.5)	0.118	B	P	-	-	-	-	-	-	-
					284 (100)	284 (100)
Total	400	200	200	0.18	299 (74.8)		62 (15.5)	7 (1.75)	24 (6)	8 (2)	-	-	-

A bilateral comparison of the premolars did not show a significant difference in terms of the number of roots present (P > 0.05) [Table 2]. This indicates that symmetry in terms of the number of roots can be a normal assumption.

The overall Kappa value for inter-examiner agreement was 0.89, indicating a very good agreement between the two examiners.

DISCUSSION

The data regarding root canal morphology available in textbooks have been historically done from the Caucasoid point of view. In contrast, research into racial variations has proved divergence from popularly accepted norms.[27,28]

The Mx1PM, in particular, has also shown variations in regard to the number of roots present in the Mongoloid versus the Caucasian populations.[28]

Our review of the literature shows the prevalence of two roots being predominant in most of the populations (61%–75%) with few exceptions [Table 1]. A study by de Lima et al.[22] in the Brazilian population showed a predominance of single-rooted Mx1PM in 80.2% of the cases. Another variation was noted by Senan et al.[21] in the Yemeni population in their study, which showed an 54.8% prevalence of one-rooted first premolars. The studies on the Indian population have not been definitive [Table 1].

There is an almost equal prevalence of single- and double-rooted premolars in most studies except one by Neelakantan et al.[10] where they found 84% prevalence of two roots in the south Indian population. Theruvil et al.[29] and Rekha et al.[30] reported and treated cases with the presence of three canals and three roots in the Mx1PM.

As the data regarding the root canal morphology are one of the most important tools for the clinician in their arsenal when planning to treat an endodontic case, the relevance of the information specific to the local population is essential. Another fringe benefit of such studies is their ability to shed more light into the origins of the local populations from an anthropological perspective.

With this in mind, the present study deals with the internal anatomy of Mx1PM of a South Indian Dravidian subpopulation using stored CBCT records in a retrospective manner and aims to add to the documented literature on the same.

CONCLUSION

1. Majority of the Mx1PM were double rooted with Type I canal configuration in all the canals studied

2. The single-rooted Mx1PM showed variations in the canal configurations, and the Type II canal configuration was dominant.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.