There are a limited number of studies in the literature evaluating the mental foramen and mental artery together. To the best of our knowledge, our study is the first to examine the relationship between mental artery blood flow parameters and various factors such as alveolar crest height and mandibular cortical index in detail. Two different imaging methods, USG and CBCT, were used in our study. Comparison of the USG and CBCT measurements showed that the mean horizontal diameter value of MF was significantly higher in CBCT. In addition, the mean value of PS/ED, which is the mental artery blood flow parameter, showed a significant difference between completely dentate, partially dentate, and completely edentulous cases in our study.
Caglayan et al.  reported that there was no statistically significant difference between USG and CBCT measurements in terms of the horizontal and vertical diameters of MF, and all MFs were oval-shaped. In our study, the comparison of the USG and CBCT measurements revealed that the vertical diameter of MF did not show a significant difference in both techniques. On the other hand, there was a significant difference in the horizontal diameter, with a higher value in CBCT. Assessment of the shape of the MF revealed an oval structure, as the horizontal diameter was higher than the vertical diameter, similar to the findings of Çağlayan et al. . The difference in the horizontal diameter measurement of MF in both techniques in our study can be explained by the fact that the bone boundaries of anatomical structures such as MF are observed more clearly in CBCT than in USG.
von Arx et al.  stated in their study with CBCT that the height of MF was significantly higher in males than in females, but they did not find a statistically significant difference in width. Çağlayan et al.  evaluated the mean horizontal and vertical diameter of MF, measured using USG and CBCT, according to gender, and although all measurements were higher in males, a significant difference was determined according to gender only in the vertical diameter measured in CBCT. In our study, the mean horizontal and vertical diameter of MF measured using USG was higher in men than in women (p > 0.05), but the mean vertical diameter of MF measured with CBCT alone was significantly higher in men than in women (p < 0.05). Our results are consistent with other studies.
Both in our study and the study of Çağlayan et al. , assessment of the distance between the MF and the alveolar crest on USG and CBCT images according to gender revealed that the mean value in the measurements made using USG was significantly higher in men than in women. A smaller distance of the MF to the alveolar crest was expected in women since their mandible is smaller [21–23].
In their study using CBCT images, dos Santos Olivera et al.  divided patients into four age groups: 18–25, 26–40, 41–55, 56 years, and older. They evaluated the distance between the MF and the alveolar crest, as well as the height and length by making vertical and horizontal measurements between the cortical areas of the MF, but they could not find a significant result according to these age groups. In our study, the mean horizontal and vertical diameter of the MF and its distance to the alveolar crest were compared according to the age groups of 18–39, 40–59, and 60 years and older on USG and CBCT images. In the USG and CBCT measurements, a significant difference was determined between the mean distance of MF to the alveolar crest and the age groups, and the mean distance of MF to the alveolar crest was found to be significantly lower in the 60 and above age group. This situation can be explained by the increase in tooth loss with advancing age and the consequent formation of alveolar crest resorption.
In our study, CBCT-acquired measurements of the horizontal and vertical diameter of the MF and its distance to the alveolar crest were compared in the MCI C1, C2, and C3 categories. The horizontal and vertical diameters of MF did not differ significantly between the MCI groups. The distance of the MF to the alveolar crest was significantly higher in the C1 group than in the C2 and C3 groups. In this case, it can be said that the resorption occurring in the alveolar crest of the mandible may be compatible with the resorption at the cortical edge of the mandible.
Baladi et al. analyzed a total of 30 ultrasound images and detected 12 weak blood flow and 18 strong blood flow. Eiseman et al.  determined strong current in the mental artery in 11 of 12 patients younger than 65 years of age, and in 9 of 19 patients older than 65 years of age. In our study, out of 120 mental arteries evaluated, 31 had strong blood flow, and 89 had weak blood flow. In terms of strong or weak blood flow, our findings appear different from other studies. This may be due to using probes of different frequencies and having study samples with different ages and ethnic groups.
There are studies in the literature showing a relationship between mental artery blood flow and alveolar bone resorption, and the USG studies of Baladi et al.  and Eiseman et al. have reported that decreased mental artery blood flow causes resorption of alveolar bone. However, in our study and in the study of Çağlayan et al. , no relationship was found between mental arterial blood flow and the distance to the alveolar crest.
The relationship between gender and blood flow strength in MF evaluated by Doppler USG was examined in the study of Çağlayan et al. , and no statistically significant difference was found between strong or weak blood flow and gender. Similar to the findings of Çağlayan et al. , no significant difference was determined between weak or strong blood flow and gender in our study.
Time-averaged maximum velocity (TAMAX) is affected by flow in the artery, the diameter of the artery, and the angle of the probe to the vessel. The pulsatility index (PI), on the other hand, is not affected by changes in the angle of the probe but is affected by the proximal and distal resistance to flow and the flexibility of the arteriovascular system [26–28].
In the study of Ethundan et al. , 30 patients were equally divided into groups of 20–39, 40–59, and 60 years and older, and the mean values of the time-averaged maximum velocity (TAMV) and pulsatility index (PI) parameters of mental artery blood flow were compared by Doppler USG for these age groups. TAMV and PI were found significantly lower in the over 60 age group than in the younger age groups. The same study reported that a decreased TAMV indicates a decreased volume flow due to atherosclerosis or a lower metabolic requirement, and an increased PI may be caused by proximal narrowing or likely from altered elasticity of the arterial system. In our study, the comparison of the parameters showing the blood flow in the mental artery measured by Doppler USG according to the age groups of 18–39, 40–59, 60 and over, revealed no significant difference between the mean values of the mental artery blood flow parameters and the age groups. Our results were different than the findings of Ethundan et al.. This may be due to the use of different probes and frequencies and the evaluation of different ethnic groups.
Ethundand et al.  evaluated the mental artery by USG in dentated and edentulous patients over 60 years of age and found no significant difference between the dental and edentulous groups and mental artery TAMV and PI values. In terms of these two parameters, our study is in agreement with the results of Ethundan et al. . There was a significant difference only between the mental artery PS/ED mean value and the completely dentate, partially dentate, and completely edentulous cases. However, since there was no significant difference in PS and ED values, this difference may not make much clinical sense.
In our study, the mental artery blood flow parameters measured were compared according to the MCI scores, and TAMAX, TAMEAN, mean flow volume values showed statistically significant differences in the C1, C2, and C3 groups, with significantly higher values in the C2 group. Since there is no other study in the literature on this subject, we recommend conducting further studies with larger sample size.
The limitation of this study is that a few data related to mental artery blood flow parameters could not be discussed comprehensively, since this is pioneering research in its field, and studies in the literature examining the relationship of the obtained data with mental artery blood flow parameters is limited. Future studies on larger samples can be carried out to compare mental artery blood flow parameters of individuals with diseases affecting blood flow with healthy control groups using USG, and further comprehensive research can be on the mental artery and foramen using MRI and MRI techniques.
In conclusion, USG is an effective method in the evaluation of the mental foramen, an anatomical structure in the maxillofacial region, and the blood supply of the mental artery. We recommend increasing the use of USG, which does not contain ionizing radiation, in the evaluations to be made in the maxillofacial region and the examination of pathological conditions in dentistry.