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ORIGINAL ARTICLE
Year : 2021  |  Volume : 11  |  Issue : 1  |  Page : 54-58

Cone-beam computed tomography evaluation of the root morphology of the maxillary and mandibular premolars in a Moroccan subpopulation: Number of roots and tooth length (part 1)


1 Department of Conservative Dentistry and Endodontics, School of Dentistry, Hassan II University, Casablanca, Morocco
2 Private Practice, Casablanca, Morocco

Date of Submission18-May-2019
Date of Decision18-May-2019
Date of Acceptance16-Apr-2020
Date of Web Publication09-Jan-2021

Correspondence Address:
Prof. Said Dhaimy
Department of Conservative Dentistry and Endodontics, School of Dentistry, Hassan II University, Casablanca
Morocco
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sej.sej_76_19

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  Abstract 


Introduction: The aim of the study was to evaluate the number of roots and tooth length of the maxillary and mandibular premolars of a Moroccan subpopulation using cone-beam computed tomography (CBCT).
Materials and Methods: The number of roots and tooth length of 919 maxillary and mandibular premolars (358 maxillary and 561 mandibular) examined by CBCT was evaluated using “Planmeca viewer” software. Statistical analysis was carried out using the Epi info software.
Results: The study showed a high prevalence of two roots for maxillary first premolars, and single root for maxillary second premolars and mandibular first and second premolars. The mean length of the maxillary first premolars (single rooted) was 21.74 mm, that of the buccal roots was 21.92 mm, and that of the lingual roots of the two-rooted teeth was 20.67 mm. The maxillary second premolars (21.4 mm) and the mandibular premolars (21.5 mm) exhibited the same mean length.
Conclusion: All premolars had a single root in most cases, except for the maxillary first premolars where two-rooted teeth were more frequent with an average length of 21.4 mm. CBCT is an exciting tool for endodontic diagnosis and treatment planning.

Keywords: Cone-beam computed tomography, mandibular premolars, maxillary premolars, root number, tooth length


How to cite this article:
Dhaimy S, Diouri M, Bedida L, Dhoum S, Elmerini H, Benkiran I. Cone-beam computed tomography evaluation of the root morphology of the maxillary and mandibular premolars in a Moroccan subpopulation: Number of roots and tooth length (part 1). Saudi Endod J 2021;11:54-8

How to cite this URL:
Dhaimy S, Diouri M, Bedida L, Dhoum S, Elmerini H, Benkiran I. Cone-beam computed tomography evaluation of the root morphology of the maxillary and mandibular premolars in a Moroccan subpopulation: Number of roots and tooth length (part 1). Saudi Endod J [serial online] 2021 [cited 2021 Jan 19];11:54-8. Available from: https://www.saudiendodj.com/text.asp?2021/11/1/54/306616




  Introduction Top


The root canal system is complex and can harbor a rich microbial flora if infected. A lack of knowledge of the root canal anatomy and/or technical skills may result in a failure to identify and treat all root canals.[1] To achieve a successful endodontic treatment, the clinician should be aware of the multiple and complex variations that can occur during the root formation.[2]

Numerous methods have been used for studying the root canal anatomy, including canal staining and tooth clearing, conventional radiographs, alternative radiographic techniques, radiographic assessment enhanced with contrast media and more recently, computed tomographic techniques and modified root canal-staining technique.[3],[4],[5],[6]

The canal staining and clearing technique and the cross-sectioning technique are invasive and result in irreversible damage to the samples. Radiographic examinations also provide only two-dimensional images, and anatomic structures can be superimposed in these images. Therefore, they do not reflect the actual morphology of the root canals.[4] Microcomputed tomography (CT) is a nondestructive high-resolution laboratory method used to study the root morphology of the extracted teeth.[7] The major problems of this technique are time-consuming and material costing. On the other hand, cone-beam CT (CBCT) imaging allows a three-dimensional (3D) evaluation of teeth and their adjacent structures.[1],[4] The images obtained by CBCT display axial, sagittal, and coronal sections and reduce the superimposition of anatomic structures. These advantages facilitate the clinician's understanding of the thorough morphology of the root canals.

Several in vivo and ex vivo research studies on the root and root canal anatomy of many subpopulations using CBCT have been published.[1],[4],[8] No studies have been published to evaluate the tooth root anatomy of Moroccan subpopulation. Therefore, the aim of this study was to evaluate the number of roots and tooth length of the maxillary and mandibular premolars of a Moroccan subpopulation using CBCT.


  Materials and Methods Top


The study was approved by the Ethical Committee of School of Dentistry, Hassan II University, Casablanca, Morocco (#104/15).

In order to comply with the principles of radioprotection (principles of justification and optimization) of ionizing radiation examinations, no cone-beam examination has been prescribed specifically for this study.

The ability and validation of the examiner to correctly analyze the images, the accuracy of his/her observation, as well as the reproducibility of the results were tested in a preinvestigation involving the roots' number and tooth length before conducting the actual study. It was carried out starting with 278 CBCT images to reach an agreement between the examiners on what should be recorded.

A total of 919 premolar teeth randomly collected from a radiology center's database in the region of Casablanca between January and December 2017 including 180 first maxillary premolars, 178 secondary maxillary premolars, 304 first mandibular premolars, and 257 secondary mandibular premolars were evaluated. The samples were made of 53.6% of females (n = 493) and 46.6% of males (n = 426), who presented with fully formed premolars, with no root canal filling, post or crown restorations, and free from teeth anomalies. CBCT examinations presenting the kinetic of metallic artifacts which could lead to a difficult interpretation were excluded.

The CBCT images were obtained using a CBCT scanner called Planmeca Promax 3D plus (Planmeca Oy, Helsinki, Finland), with the following parameters: 90 kV, 10 mA, with a field of view of 601 × 601 × 601, and 150 μm voxels. Serial sagittal, coronal, and axial views of the CBCT images from the coronal portion to the root apex of each tooth were examined carefully by an experienced radiologist according to the following features: the roots' number [Figure 1] and [Figure 2] and the tooth length [Figure 3]. The data were collected in The Digital Imaging and Communications in Medicine (DICOM) format.
Figure 1: Cone-beam computed tomography images showing the number of roots of maxillary premolars (a) single-rooted coronal section;(b) two.rooted sagittal section;(c) three-rooted axial section

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Figure 2: Cone.beam computed tomography images showing the number of roots of single-rooted mandibular premolars (a) sagittal section; (b) coronal section; (c) axial section

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Figure 3: Cone-beam computed tomography images showing the length measurement of maxillary premolars in the sagittal section

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The CBCT images were analyzed with “Planmeca viewer” software (version 3.2.7, Planmeca company, Helsinki, Finland). Statistical analysis was performed using the software Epi info (version 6, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia (US)). The roots' number data were described as percentages and the length data were described as mean and standard deviation.


  Results Top


The findings of the preexamination of the CBCT images demonstrated a high level of agreement between examiners and good reproducibility within examiners.

Maxillary premolars

Among the analyzed maxillary first premolars, 38.3% were single rooted, whereas 61.7% presented two roots. Premolars with two roots presented a mean length of 21.92 ± 1.860 mm and 20.67 ± 1.951 mm buccally and lingually, respectively; for the single-rooted premolars, the mean length was 21.74 ± 2.002 mm.

The maxillary second premolars were mostly single rooted (73.6%), whereas 26.4% presented two roots. The mean length of premolars with two roots was 21.56 ± 1.916 mm and 20.81 ± 2.053 mm buccally and lingually, respectively. The mean length of single-rooted premolars was 21.81 ± 1.804 mm. No three-rooted maxillary premolar was found.

Mandibular premolars

For the mandibular first premolars, 90.5% were single rooted and 9.5% had two roots. The mean length was of 22.11±1.355mm, 19.87±2.016mm buccally and lingually respectively for the two rooted premolars and 22.53 ± 1.970 mm for the single rooted.

Most of the mandibular second premolars were single rooted (97, 7%), and only 1 (9%) of them was two rooted. The second premolars presented a mean length of 24.76 ± 1.826 mm and 23.05 ± 2.287 mm buccally and lingually, respectively, although the single-rooted premolars presented a mean length of 22.50 ± 1.803 mm.

One three-rooted second premolar was found (0.4%), of which the mesiobuccal root measured 19.70 mm, the distobuccal root 20 mm, and the lingual root 19.30 mm.


  Discussion Top


In the current study, DICOM was used to collect the data. It is considered as the most widely adopted standard method for the exchange and management of medical images. By using DICOM, different types of images generated by any medical imaging devices such as CBCT can be integrated into picture archiving and communication systems that can be used by other applications in health-care delivery.[9]

Each tooth in the present study was measured from the coronal portion to the root apex. The use of CBCT to measure the tooth length was evaluated by different researchers. It was proven to be more accurate and reliable than the conventional periapical radiographs for estimating preoperative working length[10] and tooth length measurements.[11] Several factors contribute to the variations found regarding the tooth length and number of roots, which include ethnicity and gender. Thus, clinicians must be fully aware of these variations for a better treatment of their patients.[3]

In this study, most maxillary first premolars were found to have two roots (61.7%), which is in correspondence with many other studies.[1],[3],[5],[8],[12] Higher incidences of single-rooted maxillary first premolars were noted in the Southern Chinese population (60%).[13] No three-rooted form was detected, however, three-rooted maxillary first premolars were noted in the Spanish (2.6%),[1] Indian (2.2%),[3] German (1.2%),[8] and Jordanian (0.8%) population.[2] Our findings regarding the mean length of the maxillary first premolars were similar to those reported by Pécora et al.[14] for both the single-rooted and the two-rooted teeth.

In the maxillary second premolars, the percentages of single-, two-, and three-rooted teeth ranged from 55.3% to 90.6%, 9.4% to 44.2%, and 0.4% to 1.6%, respectively.[1],[3],[8],[15],[16],[17],[18],[19] This complies with our findings where the majority of maxillary second premolars were single rooted (73.6%), followed by two rooted (26.4%). However, no three-rooted premolar was found. The mean length of this group of teeth according to our study was in compliance with the one found in the Brazilian population.[19]

In the mandibular first premolars, the single-rooted form was the most prevalent (91.4%–100%) in many studies,[8],[20],[21],[22],[23],[24],[25] whereas the two-rooted one was present in small quantities in only some of them.[8],[21],[25] Our study showed the same results as the ones found in the literature, unlike the study conducted by Estrela et al.,[26] where most of the premolars had two roots (99%) and no three-rooted teeth were found. According to our study, the mean length of the mandibular first premolar was 21.5 ± 1.780 mm, which is in accordance with the findings of other researchers[20],[21],[23],[27],[28] in different ethnic groups using different evaluation methods.

Lastly, for the mandibular second premolars, all the previous studies agreed that this group of teeth presented one root in most cases, ranging from 98.6% to 100%,[8],[17],[23],[24],[25],[26],[29],[30],[31] which is in compliance with our results (97.7%) and contrary to the findings of Estrela et al.,[26] who conducted a study in a Brazilian subpopulation and found that all the examined mandibular second premolars had one root (100%). Three-rooted premolars were also found in our study (0.4%). The presence of three roots in the mandibular second premolar is a rare finding. This was reported in a German population (0.1%),[8] and in the systematic review conducted by Kottoor et al. (0%–2%).[30] The mandibular first and second premolars had almost identical lengths in the present study (21.5 ± 1.972 mm), as well as in other studies.[23],[27]

Identifying and accessing all root canals is particularly challenging in the endodontic treatment of teeth with atypical canal configuration; the maxillary first premolar has a highly variable canal and root morphology, frequently with two separate canals (88%) and two foramina (81%).[20] With the aim to a hermetic obturation, Dadresanfar et al.[32] suggested a tactile examination of all major buccal walls with a small, precurved K-file tip in order to find the additional buccal canal. The mandibular second premolars have earned the reputation for having aberrant anatomy. According to Vertucci classification,[33] second premolars with type 2 configuration gained 1.8 % as stated in the research of Llena C et al.[23] Al-Mahroos et al.[34] claimed that the use of a dental operating microscope allowed early recognition of the C-shaped canal system. The use of high-quality preoperative radiographs at different horizontal angulations is needful to detect the presence of extra root canal, so predictable results could be possible.

The CBCT technology offers a high accuracy when the collected clinic and conventional radiography data are not sufficiently contributory to the diagnosis. The use of CBCT database in this study will make the number of roots and tooth length measurement more correct and reproducible quantitatively as well as qualitatively. However, subtle limitations made the current data more problematic for quantitative use. Kinetic or metallic scanning artifacts due to patient mobility during acquisition obscured details of interest or caused the CT value of a single material to change in different parts of an image. In addition, the presence of teeth with root canal treatment or even dental anomalies reduced the number of samples.


  Conclusion Top


All premolars had a single root in most cases, except for the maxillary first premolars where two-rooted teeth were more frequent with an average length of 21.4 mm. Cone-beam technology offers precision in situations where the information provided by the clinical examination and conventional radiology is not sufficiently contributory to the diagnosis.

Acknowledgment

The authors would like to thank Pr. Mohamed BAITE for his help and support.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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