In dentistry, IANB is used before routine or surgical procedures planned to be performed on the mandible. 15–20% failure is observed in this frequently used anesthesia method. It is aimed to inject the anestetic into the MF around to increase the success [15]. Due to the diversity in the facial anatomies of the nations living in the world, there are many differences in the mandible and related structures [11]. Due to the fact that the mandible shows rapid growth and development until puberty, the position of MF changes in children aged 8–18 years [4, 19]. Therefore, in order to obtain an effective and safe anesthesia in the mandible, it is necessary to know well the location of the MF according to races and age.
There are very few studies in the literature that reveal the position of MF on pediatric and adult patients with malocclusion [18, 19]. Although there have been studies on the location of MF in children belonging to Turkish people [4], there have not been any studies in pediatric patients with malocclusion. Therefore, in the study, the position of the MF according to the classification of malocclusion in the PRG of children divided into different age groups of developmental age was evaluated.
The panoramic radiography technique allows the mandible and surrounding anatomical structures to be visible on a single film with a low radiation dose. This imaging method is often preferred in dentistry for the diagnosis of the disease and post-treatment evaluation [6]. According to the PRG, computed tomography (CT), which provides 3-Dimensional imaging and realistic measurement results, has a high radiation dose, so its use in pediatric patients is limited. Therefore, in the methodology of our study, PRG was used, which is the most frequently used in practice and has a low radiation rate.
It has been reported that there is symmetry between right and left MF in patients who do not have malocclusions [20, 22]. On the contrary, there are studies that report asymmetry [1, 14]. It was reported that there was a significant difference in the distance of the MF to the anterior edge of the mandibular ramus compared to lateralization in CT images of patients aged 9–18 and 19–71 years belonging to the Turkish population, but no difference was detected in other data [10]. In this study, a significant difference was observed in the anterior edge of the mandibular ramus in patients with Class 1 malocclusion, in the anterior edge of the mandibular ramus in Class 2, and in the distance measurements between the GO compared to lateralization (p < 0.05). In Class 3 malocclusion, there was no difference Decisively between right and left (p < 0.05). Since the difference between right and left in the Class 1 and 2 malocclusion group was less than 0.35 mm, it was assumed that it would not cause failure of IANB in patients.
It has been reported in the literature that the values measured in boys are higher than in girls [1]. In children of developmental age, on the other hand, higher values were found in girls due to the fact that girls enter puberty earlier than boys [16]. In addition, there are studies that report that there is no difference according to gender [3, 4, 9, 20]. In the conical beam computed tomography (CBCT) image of 100 patients aged 18–31 years with skeletal Class I, II, III malocclusions, there is no significant difference in Class 1 and Class 2 malocclusion in patients according to gender, but it was found that the distance of MF to the anterior edge of the mandibular ramus was significantly higher in male patients with Class 3 malocclusion compared to girls [18]. In our study, similar to the results of Park and Lee's study [18], there was no difference in Class 1 and Class 2 malocclusion according to gender, while all measurements except the distance to the OP in boys with Class 3 malocclusion were larger than in girls and showed a significant difference (p < 0.05). We believe that the detection of MF higher than OP in girls with Class 3 malocclusion than in boys is an important finding that should be considered in increasing the success of anesthesia.
One of the important anatomical signs used to determine the needle insertion location in IANB is OP. OP is used in the injection made for IANB in the clinic [16]. In the study conducted in adults, a significant difference was found between the skeletal class malocclusion classes and the distance of MF to the OP. MF was found to be higher in the Class 3 malocclusion group than in other groups [18]. In this study, MF, which is suitable for the literature study, was detected above all age groups and malocclusion classes, and a significant difference was observed between malocclusion classes (p < 0.05). The distance between MF and OP was found to be the lowest in the Class 2 malocclusion group and the highest in the Class 3 malocclusion group. We believe that the position of MF relative to OP in children with Class 3 malocclusion is higher than in other classes, due to the excessive development of the mandible or the more advanced position of the mandible, or due to the fact that the molar teeth do not keep up with growth and development and remain stable, the OP remains low.
The distance to the OP showed a significant difference between the age groups in all malocclusion classes (p < 0.05). MF was found to be 4.01 ± 2.59 mm above OP in the 9–13 age group and 5.05 ± 2.60 mm above OP in the 14–18 age group without distinction of malocclusion class. There was a difference of 0.75 mm between the age groups in Class 2 and 3 malocclusions and 1.65 mm in Class 1 malocclusion. Increasing the distance of MF to OP with increasing age indicates an increase in the size of the mandibular ramus in the upward direction. In many studies, it has been reported that MF changes in the upward direction with increasing age, similar to our study [12, 16, 19, 20]. In the light of our results similar to the literature studies, determining the injection site in IANB by taking into account the malocclusion classes and the ages of the patients will be useful in providing an effective anesthesia. Although MF was detected above OP at a rate of 95.45% in our study, it was observed that it was at OP level in 2.88% and below OP in 1.67%. This difference we detected was thought to be due to the fact that pediatric patients with mixed dentition period had canine and molar tooth eruption at different times.
In studies evaluating the AP position of MF in children, it was reported that the distance to the anterior increased with increasing age, and MF shifted to the posterior [7, 21, 22]. In addition to the studies that report that MF is at the midpoint of the ramus, there are no changes in its age-related position, there is a study that reports that MF is in the inferoanterior in children [12]. The different results obtained are due to the fact that the study method, race and age groups are different. In this study, it was found that the distance of MF to the posterior showed a positive correlation (p < 0.001; r: +0.298) with age and the distance to the anterior showed a negative correlation (p < 0.02; r: -0.086). A significant difference was found between the distance of the MF to the posterior and the age groups in all malocclusion classes and with the increase in age, it was seen that it approached the middle point from the posterior. As a result of the age-related growth and development of the mandible, the distance between GO and MF increases as a result of MF's change of direction in the upward direction [4, 20]. In our study, the MF and GO distance showed a significant difference between age groups in malocclusion classes (p < 0.05). We think that the distance between MF and GO shows a positive correlation with age, due to the growth of the mandibular ramus in the vertical direction and the increase in bone in the basis mandibulae.
The study was carried out on a limited number of people who applied to the hospital for various reasons. In addition, the change in the OP due to the difference in eruption times of the canine and molar teeth, which form the OP, shows the limitation of this study. Therefore, further clinical studies with larger sample have to be conducted to determining the location of the MF.