Modern dental treatment has seen a rise in the use of CBCT due to improved scan quality, cost efficiency, and reduced radiation exposure [28]. Ferlin et al.’s review of literature suggested CBCT scans to be the best modality for the evaluation of CS, where conventional radiographic techniques (periapical and panoramic radiographs) proved less effective [8]. Many studies investigating CS and its ACs have evaluated CBCT scans [1, 2, 5,6,7, 11,12,13, 17,18,19, 25, 29, 30].

The CS exists as a distinct anatomical entity with reported prevalence ranging from 66.5% to 100% in different population groups [1, 2, 8, 11, 12, 18, 19, 30]. The bilateral presence of CS has been reported to range between 46 and 100% [1, 2, 11, 12, 18, 19]. The present study found that the vast majority of South African patients (99.6%) presented with CS. When present, it frequently occupied a bilateral distribution (98.8%). Variation in the prevalence and sidedness of CS may be attributed to inherent differences between population groups, or differing study designs and methodology. When reporting the prevalence of CS, Wanzeler et al., Ghandourah et al., and Gurler et al. differentiated between CS and its ACs, thus observing a higher prevalence of the structure (88%, 100%, 100%, and 99.6% respectively) [1, 2, 18]. Other authors, such as Aoki et al. and Anatoly et al. regarded CS and its ACs as a single structure and reported CS as absent if no ACs were present. This differing methodology may have contributed to a lower recorded prevalence of CS in these studies (66.5% and 67% respectively) [12, 19].

The present study found the mean diameter of CS to be 1.08 mm on both the right and left sides. This measurement is comparable to the mean diameters of CS reported by Gurler et al. and Sedov et al. in Turkish and Russian populations at 1.37 mm and 0.95 mm respectively [2, 31]. The range of diameters recorded by Gurler et al. (0.75 mm-2.25 mm) and Sedov et al. (0.3 mm-2.1 mm) is similarly comparable to that of the present study (05 mm-2.39 mm) [2, 31]. Differences in the reported diameters between studies may be attributed to the varying minimum detection diameter threshold selected (Gurler et al.: 0.75 mm [2], Sedov et al.: none [31], and the present study: 0.5 mm). de Oliveria-Neto et al., suggested that comparison of the mean diameters of CS in different populations is difficult due to a lack of available data and differences in study methodologies [30].

No relationships regarding the prevalence or sidedness of CS and sex were found in the present study. This is consistent with studies conducted in Brazilian, Belgian, Turkish, German, Chinese, Australian, and Cypriot populations [1, 3, 5, 7, 11, 17, 18, 29]. Age was also shown to have no effect on the presence or sidedness of CS, in keeping with studies of Brazilian, Turkish, Russian, and Chinese populations [1, 6, 7, 12, 13, 17, 19]. Furthermore, the present study found that ethnicity in the South African context had no influence on the presence or sidedness of CS. These findings suggests that CS should routinely be observed bilaterally—irrespective of age, sex, or population group.

The prevalence of ACs varies substantially between different populations, with ranges reported between 8.17 and 100% [5,6,7, 11,12,13, 17,18,19, 29] (Table 4). More than half the South African population (58.8%) presented with at least one AC, in keeping with the findings of Machado et al. in a Brazilian population [6]. This finding however differed notably from other populations [5, 7, 11,12,13, 17,18,19, 29]. Generalisation regarding the prevalence of the ACs can therefore not be made. The differences in the prevalence of ACs may represent true anatomical differences between populations based on genetic, ethnic, and geographical factors [3, 32]. Alternatively, such differences may be attributed to inconsistencies in study design, including; minimum detection diameter threshold, inclusion criteria, CBCT machine, software, voxel size, slice thickness, and the investigators experience [29]. Şalli and Öztürkmen recorded the lowest prevalence of ACs (8.17%) but used a larger minimum detection diameter [13] than other studies [6, 11, 18, 29]. Beyzade et al. recorded the highest prevalence of ACs (100%) in a Cypriot population, however, evaluated the smallest sample (n = 91) which may have influence the results [29].

The ACs of the present study recorded a mean diameter of less than 1.0 mm. This was smaller than the mean diameters found in Brazilian, Turkish, and Chinese populations respectively [6, 7, 17]. These studies reported mean diameters of 1.19 mm, 1.07 mm, and 1.1 mm respectively [6, 7, 17]. Yeap et al. reported a substantial difference between the widest (1.08 mm) and narrowest (0.71 mm) diameters of CS in the Australian population [11]. This study furthermore established the oval nature of CS [11]. The mean diameter of the ACs recorded in the present study may be attributed to the use of a smaller minimum detection threshold when compared to others [6, 17]. Yeap et al. however suggested the diameter of ACs to vary within single canals and between subjects [11]. Variation of mean diameter seen between different populations may therefore be due to differences in study design as opposed to true anatomical differences.

Previous investigations found ACs most commonly terminated in the anterior palatal region of the maxilla (91.1% and 76% respectively) [6, 19]. Less common locations include buccal (5.1% and 12%) and transversal (3.8% and 12%) positions [6, 19]. The present study found fewer ACs terminating in a palatal position (57.2%), while more occupied buccal (21.7%) and transversal (10.5%) positions. This may be attributed to the use of a greater number of AC termination locations used in the present study. The most common points of AC termination in the present study were palatal of the central incisors and buccal of the interproximal region between the central incisors. This was consistent with the findings of previous investigations which found that ACs most commonly terminated in this region [5, 11, 12, 18].

The course of the ACs is poorly documented in the literature [7]. In the present study, all ACs progressed through the maxilla from a superior point of origin to an inferior point of termination. The majority of the ACs demonstrated a straight vertical configuration (72%). Yeap et al. reported the potential for complex AC configurations, with some cases displaying convergence or various branching patterns [11]. The present study did not find many of these complex configurations.

CS is a clinically significant structure which may affect surgical procedures in implantology, oral surgery, endodontics, and periodontology [8, 21,22,23,24, 26, 27]. The most frequently reported clinical complication associated with damage to CS is post-operative pain and paraesthesia [21,22,23]. The possibility of severe intra-operative haemorrhage and failure of dental implant osseointegration has additionally been reported following damage to CS [8, 21,22,23]. Furthermore, CS has proven to be a source of diagnostic uncertainty, in some instances resembling periapical pathology with the potential to lead to endodontic mismanagement [26, 27]. The high prevalence and complex anatomy of CS and ACs found in the present study supports the recommendation of routine CBCT scanning and evaluation prior to surgical intervention in the anterior maxilla, in order to reduce the risk of complications [11, 25].