For a good endodontic procedure, understanding the intricate three-dimensional root canal structure and potential diversifications is necessary. A comprehensive conceptual description; thus, an understanding of endodontic morphology can greatly reduce the difficult challenges encountered during access cavity planning, cleaning, forming, and filling procedures of the root canal system. In the literature, root canal anatomy has been identified and controversially debated [29–31].
CBCT was used in this research to examine the root structure and root canal morphologies of maxillary premolars in a Saudi subpopulation. The clinical effectiveness of endodontic procedures depends on a thorough understanding of root anatomy and the likelihood of variance in root canal pattern, as unobserved root canals can cause failure of treatment. As a result, the current research focused on the maxillary first and second premolars in order to better understand their variability in a Saudi subpopulation. The reports of the variations of premolars in the anatomic studies and the clinical cases are well mentioned in the literature and states that these are the most challenging teeth to be treated endodontically due to the wider variations in the root canal system [32]. The age, gender, ethnicity were counted as depending factors [32, 33]. For this goal, we examined a enough sample size of CBCT imaging data to decrease the sampling bias.
To accomplish an effective imagining of the root canal system, various methods [22–29] have been used. In vitro investigations have been mandated due to their dominance over in vivo investigations' inherent limitations [34]. In vivo and in vitro studies, however, can also offer useful knowledge to clinicians. In comparison to traditional 2D radiography, CBCT is an excellent tool for evaluating the root and canal morphology [28]. CBCT has been used in a number of studies to assess the morphology of maxillary premolars [35, 36]. Because of its capability to test and measure root canal anatomy in three dimensions, CBCT is said to be a better method for noticing root canal morphology than conventional periapical radiography [37, 38]. The data for this retrospective analysis were gathered from Ha'il city's dental clinics, which offer free dental services to a large portion of Saudi Arabia's population from various regions. A CBCT imaging database was accessed regardless of voxel size to achieve a larger sample size without exposing a large number of patients to unnecessary radiation.
The clinician can easily define and understand the degree of treatment difficulty with an appropriate root canal configuration classification. Different classifications for configuration types have been proposed in the literature [4, 39, 40], with the classifications proposed by Weine et al. [39] and Vertucci [40] being the most widely used.
The prevalence of one root was stated to be 22–66% in maxillary first premolars, 33–84% in two roots, and 0–6% in three roots [41–45]. The prevalence of one root was recorded to be 69.6–90.3% in maxillary second premolars, 9.7–29.7% in two roots, and 0–1.6% in three roots [45–48].
Atieh [50] found that the majority (80.9%) of maxillary first premolars had two roots among Saudi population, while one and three roots were found in 17.9% and 1.2%, respectively. Elkady and Allouba [51] studied the root anatomy of maxillary premolars using CBCT. They found that 28.3% of maxillary first premolars had one root and 71.7% had two roots. An important anatomical variation in maxillary premolars is the presence of three roots. This feature was reported in 0-11.7% of first premolars [49–51]. In the present study, the most commonly detected root anatomy of maxillary first was two roots (58.6%), followed by single- rooted (39.8%) and three-rooted (1.6%). The current results are in same line with Maghfuri et al [52], who reported that the two roots were most commonly detected morphology (61%), followed by single-rooted (36%) and three-rooted (3%). In Saudi population, additional research by using CBCT were conducted. Our study were in agreement with previous reports, where two roots were 75.1%, followed by one root (23.7%) and three-rooted (1.2%) [53]. In additional report using optical radiography, sectioning methods and visual radiography in the same population, the occurrence of double-rooted in maxillary first premolars was 80.9%, followed by single-rooted 17.9%, and three-rooted 1.2% [50]. Regardless of the approach, this research provided similar findings to ours. In addition, we found a higher prevalence of two-rooted maxillary first premolar in our sample than to Yemeni (44.4%), Turkish Cypriot (44.8%), and Spanish population (51.4%), respectively [44, 54, 55]. However, we found a low incidence of single-rooted maxillary first premolars than to Yemeni populations (54.8%), North Indian populations (53.6%), and Chinese subpopulations (66%) [44, 56, 57].
In the current study, all of the specimens for maxillary first premolar corresponded to Vertucci’s classification [40]. The most common canal configuration was Type IV (57.8%), which is lower than other investigations in the same population, including Saudi Arabians (75%) [52], (69.1%) [53], and (63%) [50]. It is with the same line to other studies from Yemen (55.6%) [44], from Turkish Cypriot population (59.5%) [58]. It is also higher than in India (33.2%) [56], and in Chinese subpopulation (51%) [57].
Pecora et al. [21] reported that 90.3% of maxillary second premolars (n = 435) showed single roots, whereas 9.7% possessed two roots. Recently, Elkady and Allouba [49] found that 76.4% of maxillary second premolars found one root and 23.6% exhibited two roots. An important anatomical variation in maxillary premolars is the presence of three roots. This feature was reported in in 0–5% of second premolars [49, 51] in Saudi Arabian population. Up to three-rooted teeth were found in maxillary second premolars. Single-rooted had the highest incidence, followed by double-rooted and three-rooted (0.3%). Our finding were that 83.2% of teeth have one root, and 15.8% have two roots. Extra studies in Saudi Arabia have found one root in 76.4% and 67% of teeth, two roots in 23.6% and 30% of teeth, and three roots in 0% and 3% of teeth [49, 59].
The popular of maxillary second premolars have one root with one canal, according to popular belief [60]. Some studies maxillary second premolars had single canal between 27.70% and 48.66%, and the incidence of two canals between 50.64% and 72.30% [61]. Other researchers found a high incidence of single canals (64.1% and 67.3%) at the apex of maxillary second premolars and a comparatively low frequency of two canals (35.4% and 32.4%) in this area [62].
According to the findings, 60.4% of maxillary second premolars had only one canal. The absence or presence of three canals in maxillary second premolars has been recorded in a variety of studies, with incidences ranging from 0–2% of teeth [2, 63, 64]. Three canals were found in 1.0% of the total sample in this analysis, which is consistent with previous findings.
According the previous studies among a Portuguese population, woman subjects had less roots in maxillary premolars with a statistically higher in the maxillary first premolars [65]. However, in the Spanish population, there was no statistically important link between the numbers of roots and gender [35]. In the present reserach, there was a statistically significant connection between gender and the number of roots or gender and the root canal structure in maxillary first and second premolars, with male having more roots.
CBCT has been used to determine the symmetry in both side for root canal morphology in many studies. In Saudi patients, symmetry in right and left was found in 88.5% for the number of roots and 77% for canal pattern in maxillary first premolars [49], and symmetry of 64% was found in a Chinese population for roots number as well as root canal types [57]. Bilateral symmetry was found in 84% of maxillary second premolars for the number of roots and in 76% for canal configuration [49]. Previous studies found a high degree of symmetry in the number of roots and canal structure in maxillary second premolars, which is consistent with the current findings.
A sufficient access opening and root canal file will also aid in the discovery of extra root canals, so we recommend that in special cases, the pulp access opening be changed from the standard oval to a variety of shapes, depending on the position of the extra root canals as defined by CBCT.
The current study represented the internal root anatomy of first and second premolars in Saudi residents and, to some degree, provided a theoretical basis for clinical care. The sample size and experimental approach had a strong influence on the results of anatomical forms of root canals. There are, however, a few drawbacks that must be addressed. The sample size should have been greater because this was a single-center analysis. Furthermore, the spatial resolution of the CBCT used in this analysis was lower than that of micro- and nano-CT, which may have affected the findings. Further multicenter research using advanced techniques such as micro-CT may be able to overcome the current study's limitations.