Saudi Endodontic Journal

REVIEW ARTICLE
Year
: 2022  |  Volume : 12  |  Issue : 3  |  Page : 227--235

Root and root canal morphology of maxillary premolars in the Saudi population: A review of literature


Roqayah Aljuailan 
 Department of Conservative Dental Sciences, College of Dentistry, Qassim University, Buraydah, Kingdom of Saudi Arabia

Correspondence Address:
Dr. Roqayah Aljuailan
Department of Conservative Dental Sciences, College of Dentistry, Qassim University, Buraydah
Kingdom of Saudi Arabia

Abstract

Introduction: To achieve the desired treatment outcomes following root canal treatment, clinicians must have extensive knowledge of root and root canal morphology before commencing the treatment. Hence, this article aimed to review the studies performed on the root and root canal morphology of maxillary premolars in the Saudi population and to investigate sex differences and bilateral occurrence of the morphology of these teeth. Materials and Methods: A thorough search of MEDLINE/PubMed, Scopus, and Google Scholar databases was conducted. Nineteen studies concerning anatomical as well as case report studies were included and over 5120 permanent maxillary premolar teeth were evaluated in these studies. Results: Thirteen anatomic studies and six case reports included in this review examined root and/or root canal morphology of maxillary premolars in four provinces of Saudi Arabia. Various study methodologies have been implemented in these anatomic studies. The maxillary first premolars (MxFPs) showed two roots and two canals in an average of 63.2% and 92.2%, respectively. The majority of maxillary second premolars (MxSPs) had one root (84.4%) and two root canals (57.7%). Type IV canal configuration is the most frequent configuration in MxFP with an average of 64.4%, whereas Type I was seen in 47.1% of the MxSP. Conclusion: Both maxillary premolars showed anatomical diversity and this emphasizes the need for attention during endodontic management. In general, there are sparse studies on the Saudi population discussing the study's objectives and further studies are required for evaluating root and root canal morphology of maxillary premolars.



How to cite this article:
Aljuailan R. Root and root canal morphology of maxillary premolars in the Saudi population: A review of literature.Saudi Endod J 2022;12:227-235


How to cite this URL:
Aljuailan R. Root and root canal morphology of maxillary premolars in the Saudi population: A review of literature. Saudi Endod J [serial online] 2022 [cited 2022 Sep 24 ];12:227-235
Available from: https://www.saudiendodj.com/text.asp?2022/12/3/227/354834


Full Text

 Introduction



A thorough knowledge of root and root canal morphology of human permanent teeth and possible variation in their anatomy is essential for providing successful surgical and nonsurgical root canal treatment. Locating all canals and the complete chemo-mechanical instrumentation, followed by the adequate sealing of all portals of entry and exit to impede any further communication is crucial for preventing or for achieving resolution of peri-radicular lesions.[1],[2],[3] Costa et al. found that the frequency of apical periodontitis in teeth with untreated canals was significantly greater than in teeth with treated canals.[1]

Posterior teeth most frequently require root canal treatment and maxillary premolars accounted for 15.8%–21.5% of endodontically treated teeth.[4],[5] Various in vivo and in vitro techniques have been used to study the external and internal morphology of human teeth.[6] Literature shows that maxillary premolars could be presented with variable morphology and that could complicate the root canal treatment.[7],[8],[9] Maxillary first premolar (MxFP) typically presents as two roots and two root canals, whereas maxillary second premolar (MxSP) has one root and one or two root canals.[10],[11] In a study that assessed maxillary premolars by examining cone-beam computed tomography (CBCT) images, one-rooted maxillary premolars with two canals were found in about 58.0% of samples.[12] Sardar et al. examined 100 patients, clinically and radiographically, and they found that 57% of patients had a second canal in the maxillary second premolar and there was no significant difference between the results in males and females.[13]

Ethnicity is one of the factors that influenced the outcomes of morphological studies.[14],[15],[16] Therefore, having a comprehensive knowledge of the root canal morphology of each population is advantageous to clinicians. The current study aimed to review the anatomic studies and clinical cases that reported the internal and external anatomy of maxillary premolars in several provinces of Saudi Arabia. In addition to that, the assessment of anatomical variation between males and females and the degree of morphological bilateral symmetry of these teeth were considered.

 Materials and Methods



MEDLINE/PubMed, Scopus, and Google Scholar databases were searched for relevant articles. A combination of the following search keywords was used: “maxillary premolar,” “maxillary bicuspid,” “number of roots,” “number of canals,” “root canal morphology,” “extra roots,” “dental anomalies,” “abnormal root morphology,” and “Saudi subpopulation/population.” A total of 397 studies were found in the preliminary search. After the removal of duplication, retrieved abstracts of published manuscripts were screened for eligibility. A bibliography of the eligible articles, previous review studies on the Saudi population,[17] and issues of the Saudi Endodontic Journal (Since 2011) were manually checked for additional studies.

Anatomic studies and clinical case reports that evaluated the root and/or root canal morphology of maxillary permanent premolars of the Saudi Arabian population/subpopulation that were published in peer-reviewed journals were included in the current review. Case reports that did not mention the patient's nationality were excluded.[18],[19],[20] Studies that did not examine the anatomical feature in each specific maxillary premolar tooth were also excluded.

Twenty studies met with the inclusion criteria and were reviewed in the full text except for one article, which could not be retrieved and was thus excluded.[21] Nineteen studies[22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32],[33],[34],[35],[36],[37],[38],[39],[40] with over 5120 permanent maxillary premolars were evaluated in the studies contained in this review [Figure 1]. Information that includes publication year, authors, number of specimens/patients, age and gender of included patients, region, and methodology used were recorded. The data were analyzed and weighted averages were determined (if applicable) for each of the following:{Figure 1}

Root fusion, number of roots, and root canals per toothNumber of root canal orifices and type of root canal configuration per tooth according to the 8 Vertucci's classifications.[3] Additional canal configurations described in some of these studies were categorized as “others” [Table 1]. One study classified their samples using Weine classification and to combine its results into the current review, the author reclassified them into Vertucci's classification according to the definitions and figures provided in the study[22]Sex differencesBilateral symmetry/asymmetryMorphology of apical region, accessory canals, inter-canal communications, and isthmuses.{Table 1}

The data from each anatomic study were entered in an Excel sheet and the weighted averages of the studied morphological features (e.g., single-rooted) were computed by dividing the total number of teeth having that feature by the total number of samples in all studies that evaluated it.

Data from clinical case reports were extracted as follows:

Patient's personal information (age, gender, etc.)Type and side of premolar tooth studied according to the FDI notation systemManagement performed (clinical examination, radiographic examination, or clinical procedure)Reported anatomic variations and/or developmental anomalies.

 Results



Overall, 13 anatomic studies and six case reports were included in this review that examined root and/or root canal morphology of maxillary premolars in four provinces of Saudi Arabia (central, eastern, western, and southern regions). The techniques were used in the anatomic studies comprising of tooth clearing,[22] clinical and radiographic examination,[40] periapical radiographs evaluation,[23] in vivo CBCT,[24],[25],[27],[28],[29],[31],[32],[39] ex vivo CBCT,[26] and micro-CT.[30] A total of 2677 participants with 5122 maxillary premolars (2718 MxFP and 2404 MxSP) were contained in anatomic studies (however, three studies did not report the number of subjects) with ages ranging from 16 to 71 years (7 studies mentioned the age of the included patients). All studies reported their results on root and root canal morphology by the number of teeth except Alqahtani et al.[40] reported their data by the number of patients instead.

The root morphology of MxFP was studied by seven studies[22],[24],[25],[26],[27],[28],[29] that were included in the weighted average which gives a total of 1851 teeth. The majority of MxFPs had 2 roots (63.2%) while 35.5% had 1 root and 1.3% had 3 roots. Only one study examined root fusion of MxFPs and 44.7% of two rooted teeth had two separate roots, while 36.2% had two fused roots.[22] For MxSP, six studies evaluated root morphology[24],[25],[27],[28],[29],[30] that were included in the weighted average giving a total of 1587 teeth. The vast majority of MxSPs had one root (84.4%), while 15% had 2 roots and 0.6% had 3 roots [Table 1].

The internal anatomy of MxFP and MxSP was examined by 11 studies.[22],[23],[24],[25],[26],[27],[28],[29],[30],[39],[40] With regard to the number of canals, two canals were present in 1626 (92.2%) and 853 (57.8%) in MxFPs and MxSPs, respectively. Three root canals were found in 26 (1.5%) of MxFPs whereas it was 12 (0.8%) of MxSPs. Type IV canal configuration prevailed over 1063 (64.4%) of MxFPs, but it has been found in only 219 (15.8%) of MxSPs. Type I canal configuration was reported in almost half of MxSP samples (47.1%). However, it coincides with only 103 (6.2) of MxFPs [Table 1]. One study evaluated the number of canal orifices in MxFPs and two canal orifices were found in 90.6% of the samples.[27] In MxSP, two studies investigated the number of canal orifices and the average of one canal orifice was found to be 67.2%.[27],[30] When the number of apical foramina was considered, Elnour et al. reported one apical foramen detected in 34%, two apical foramina in 50%, three in 11%, four in 4%, and five apical foramina in 1% of maxillary second premolars.[30] In the same study, they found accessory canals and intercanal communications were present in 8%, an apical delta was observed in 7% and isthmuses were detected in the middle and coronal third (2%) of MxSP.[30] Moreover, Boreak et al.[39] assessed the root canal cross-sectional shape at different root levels in maxillary premolars and they found the circular cross-sectional shape in most of the maxillary premolars except for the maxillary right second premolars.

Sex differences

Four studies evaluated the morphological sex differences of maxillary premolars in 929 male and 1114 female participants.[23],[25],[27],[31] One-rooted MxFPs were found to occur more frequently in females, whereas three-rooted MxFPs were reported in males more than females. Females have a slightly higher prevalence of the second canal in MxFP than males (95.4% vs. 91.1%). In addition, the average of the second root and second canal in MxSP was higher in males than females [Table 2]. Two studies reported canal configurations among sex in MxFP and MxSP.[25],[31]{Table 2}

Bilateral symmetry\asymmetry

Three studies assessed the symmetrical occurrence of morphological features of root and root canal systems in the included patients.[24],[25],[32] MxFP showed a range of 6.5%–14.9% and MxSP 3.7%–16% asymmetry regarding the number of roots. Canal configuration in both maxillary premolars showed a higher degree of morphological asymmetry. [Table 3] summarizes the results of the studies.{Table 3}

Anatomical variation studies and clinical case reports

No included studies in the current review examining anatomical variations in root and root canal morphology in maxillary premolars were found to fit the inclusion criteria.

Eleven teeth were included in the six case reports,[33],[34],[35],[36],[37],[38] with the occurrence of three roots or three canals being the most common reported anatomical variation in the maxillary premolars. [Table 4] summarizes the clinical case reports of maxillary premolars in the Saudi population.{Table 4}

 Discussion



Despite major technical advances in endodontic procedures, root canal treatment may impose a clinical burden on clinicians due to its pronounced complexity and the variation in the anatomy of human teeth. Differences in ethnicity are one of the factors that may explain the reported variations in human teeth morphology.[15],[16],[41] Age, gender, and study methodology have affected the findings of anatomic studies.[14],[31],[42] This study analyzed the data reported in previously published studies with variations in study methodology and sample number. Out of 13 studies conducted in four regions, 2718 MxFP and 2404 MxSP teeth were investigated. Eight of these studies used in vivo CBCT images for the evaluation of root and root canal morphology of maxillary premolars.

The current review showed that MxFP mostly has two roots (63.2%) and two canals (92.2%), whereas one root and one canal have been found in 35.5% and 6.2% of samples, respectively. In comparison with studies concerning different populations, two rooted MxFP was found in 86% of an Indian population,[43] 68.4% of a Jordanian population,[44] 53.7% of a Turkish population,[45] and 33% of a Chinese population.[46] Three-rooted or three canalled maxillary premolars, also known as ridiculous and miniature 3-canalled molars,[10],[47],[48],[49] has an overall average of 1.9% (3-rooted) and 2.3 % (3-canalled) in this study. Literature showed a wide range in the prevalence of three rooted MxFP ranging from 0.4% to 9.2%.[8] In a systematic review evaluating the prevalence of the second root and root canal in maxillary premolars in studies that used CBCT for assessment, the proportion of a second root was 43.2% and the second canal was 77.2%.[50] Type IV canal configuration is the most frequent configuration with an average of 64.4% followed by Type II (17.9%). This is in accordance with a previously published report reviewing the internal morphology of MxFP.[8]

The present study results showed that the presence of one root in MxSPs is a predominant feature (84.4%) followed by two roots having an average of 15%. In comparison to other populations, one rooted MxFP was found in 96.2 of a Chinese population,[12] 86% of an Indian population,[43] and 55.3% of a Jordanian population.[9] MxSP showed two canals with an average of 57.8% of included studies. These results occur in the same range reported in previous studies; they found that two canalled MxSP were 59.1% of a Spanish population,[51] 54.3% of a Chinese population,[52] and 50.6% of the Turkish population.[53] However, in a study examining root canal morphology in the Jordanian population, they reported a frequency of 85.7%.[9] Martins et al. found that the proportions of a second root and second canal in MxSP were 8.5% and 43.9%, respectively.[50] In respect to canal configuration, Type I Vertucci was more frequently found in an average of 47.1% followed by Type II (16%) and Type IV (15.8%). Similarly, Type I canal configuration was commonly reported with the highest proportions in the previous studies of different populations.[51],[52],[54] In contrast, Type II was reported more frequently in other studies.[55],[56]

With regard to sex differences, the current study results showed that the average of having the second root in maxillary premolars was higher in males than females. Furthermore, males have a higher prevalence of the second canal than females in MxSP but this is not the case for MxFP, in which the opposite is true. In a systematic review study examining the prevalence of the second root and a root canal about gender in maxillary premolars, males presented a higher proportion of the second root than females for both premolar teeth, but this is not statistically different.[50] In the same study, the data evaluating the probability of a second canal in maxillary premolars showed higher proportions of a second root canal in males.[50] Finally, there are only very few available studies assessing root and root canal morphology of maxillary premolars in the Saudi population while analyzing the difference between the sexes.

While considering anatomical symmetry, the contained studies in the present review showed that number of roots in maxillary premolars have a lesser degree of asymmetry than canal configuration. A study assessing root and root canal morphological symmetry of maxillary premolars in an Indian population reported 81.5% symmetry in number of roots and canals.[57]

Most of the clinical case reports on maxillary premolars in the Saudi population report three rooted or three canalled variations. From the current review results, multi-rooted or multi-canalled variation occurs more frequently in MxFP than second premolar teeth. Literature reporting cases of maxillary premolars having more than two roots or canals variations is not uncommon.[58],[59],[60],[61],[62],[63],[64],[65]

One of the limitations of this review is the varying methodology of the included studies. However, a major advantage that could be considered is that most of the contained studies are in vivo studies that reflect an approximation to the clinical situations. Even though the weighted averages in the present review represent the common anatomic features of maxillary premolars, morphological variations of these teeth are expected. A careful reading of preoperative radiographs, the floor of the pulp chambers, and applying Krasner and Rankow symmetry laws would be very helpful in detecting teeth with varying anatomy.[66] Furthermore, a sudden narrowing or disappearing of the canal while studying a straight and exposed periapical film suggests that the canal is dividing at this point.[3] CBCT exposure is recommended when teeth with unusual anatomy or treatment failures are encountered as it offers a detailed study of teeth and the surrounding structures.[67]

 Conclusion



The maxillary first premolars are mostly two-rooted teeth with two root canals and the majority of maxillary second premolars are single rooted with two canals. The average of having a second root in maxillary premolars was found higher in males than females. Clinicians should be aware of the possibility of asymmetry in root canal morphology while treating contralateral maxillary premolar tooth in the same individual. Among case report studies, MxFP having three roots or three canals is frequently reported in the Saudi population. In general, there are sparse studies on the Saudi population discussing this study objectives, and further research is needed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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