Differences in Distance between Mandibular Premolars Root Apices and the Mental Foramen by CBCT Imaging according to Sex in Patients Referred to Dental School of Ahvaz Jundishapur University of Medical Science in 2020-2021

Background and Objectives Knowing the location of mental foramen during common dental procedures such as local anesthesia, periapical and endodontic surgeries, extraction of impacted teeth and enucleation of cysts and tumors is important. Due to the limitations of available information about this anatomical structure, the aim of this study was to evaluate the relationship between root of mandibular premolar teeth and mental foramen. Subjects and Methods In this retrospective study, CBCT images of 94 patients (47 men and 47 women) who referred to the radiologic department of Ahvaz Jundishapur Dental School in 2020-2021 were recorded and evaluated. Finally, the data were analyzed to evaluate the difference in distance between mandibular premolar teeth root apex and the mental foramen in men and women, using SPSS software version 24 and t-test. Results There was no statistically significant difference for any of the roots of the second right mandibular premolar, first and second left mandibular premolars regarding the distance between the root apex and the mental foramen in men and women. But this distance in the root of the first right mandibular premolar was significantly greater in men than women (p = 0.008). Conclusion This study showed that except for the root of the first right mandibular premolar, there is no significant difference in the distance between the apex of the mandibular premolars to the mental foramen between men and women.


Extended Abstract
Introduction he mental foramen is an important reference point on the external surface of the mandible, through which the mental nerve (a branch of the inferior alveolar nerve) leaves the mandible and provides the senses of the anterior areas of the chin, lower lip, as well as the buccal gingiva of the anterior teeth and premolars of the mandible.Although in most studies, the mental foramen is located in the area under the second premolar of the mandible, but its position may change from under the canine to under the first molar.Since no health care method is risk-free, one of the risks associated with dental treatments is damage to anatomical structures, including the mental nerve, which may have a major impact on the patient's quality of life.
In dentistry, endodontic treatment is one of the largest sources of reported negligence claims and accounts for a percentage of reported nerve injuries.Nerve injuries related to endodontics may be caused by periapical infections, use of local anesthesia, excessive use of instruments, use of cleaning agents and drugs, root canal filling, and endodontic surgery.Since the risk of defects and complications associated with endodontics is related to the proximity of the roots to any important anatomical structure, 3-dimensional knowledge of the local anatomy is very valuable for treatment planning.For example, accurate preoperative assessment and awareness of the mental foramen position in relation to the treated tooth helps to reduce the risk of mental nerve injury.Because CBCT is used to accurately evaluate the relationships between anatomical structures and it seems that there is no study that measures the distance of the first and second premolar on the right and left side of the mandible to the metal foramen separately for each tooth and compares men and women in the Iranian population, in this study, we decided to investigate this relationship between the roots of mandibular premolar teeth and the mental foramen using CBCT images.

Methods
In this retrospective study, CBCT images of 94 patients (47 men and 47 women) who referred to the oral and maxillofacial radiologic department of Ahvaz Jundishapur Dental School in 2020-2021 were recorded and evaluated.In order to determine the position of the mental foramen on the buccal cortical plate in the cross-sectional view where the apexes of the first and second premolar teeth of the mandible were observed, the procedure was as follows: in the section where the mental foramen was clearly visible, a line was drawn parallel to the horizon in the area the upper border of the mental foramen.Then, the distance of this line was measured as the upper border of the mental foramen to the most prominent (the lowest) point of the lower border of the mandible.Then, when the roots of the mandibular premolars were clearly seen, the line that represents the upper border of the mental foramen, based on the distance obtained in the previous step, it was drawn again.The meeting point of this line with the cortical border of the buccal plate indicates the location of the mental foramen.Therefore, the distance of the apexes of the first and second premolar teeth of the mandible to this line was determined and was recorded and measured as the shortest distance between the apexes of the mandibular premolar teeth and mental foramen.If the root apex was higher than the mental foramen, the distance was recorded with positive values, and if the root apex was at the same level or lower than the mental foramen, the distance was recorded with negative values.Finally, the data were analyzed to evaluate the difference in distance between mandibular premolar teeth root apex and the mental foramen in men and women, using SPSS software version 24 and t-test.

Results
1-Determining the distance from the end of the root of the mandibular first premolars to the mental foramen in women and men referring to Ahvaz Dental Faculty and comparing them.as seen in Table 1: In the 4th right mandibular tooth: The results of the independent t-test showed that there was a significant difference between the average distance of the root end of the 4th right mandibular tooth to the mental foramen in men and women (p=0/008).(chart1) In the 4th left mandibular tooth: The results of the independent t-test showed that there was no significant difference between the average distance of the root end of the 4th left mandibular tooth to the mental foramen in men and women (p=0/109).(chart2) 2-Determining the distance from the end of the root of the mandibular second premolars to the mental foramen in women and men referring to Ahvaz Dental Faculty and comparing them In the 5th right mandibular tooth: The results of the independent t-test showed that there was no significant difference between the average distance of the root end of the 5th right mandibular tooth to the mental foramen in men and women (p=0/155).(chart3) In the 5th left mandibular tooth: The results of the independent t-test showed that there was no significant difference between the average distance of the root end of the 5th left mandibular tooth to the mental foramen in men and women (p=0/270).(chart4)

Conclusion
This study showed that except for the root of the first premolar of the right mandible, there is no significant difference in the distance between the apex of the mandibular premolars and the mental foramen between men and women.Also, the closest root of the premolar teeth to the mental foramen in women is related to the root of the left first premolar tooth and in men it is related to the root of the second right premolar tooth, which requires more accuracy and evaluations during root treatment or surgical treatments on these roots and calls for more care and caution from the clinician.The results of this research, which was conducted in a small subset of Iran's population, can be considered during root canal treatment and other oral surgery procedures in that area.

Compliance with ethical guidelines
Considering that the study is retrospective and is performed on the CBCT images available in the archive of the radiology department, there are no specific ethical considerations regarding its implementation.

1 . 2 .
Distribution of the average distance from the end of the root of the first premolar of the right mandible to the mental foramen in men and women T Distribution of the average distance from the end of the root of the first premolar of the left mandible to the mental foramen in men and women

Table 2 .Chart 3 .
Descriptive indicators of the distance from the end of the root of mandibular second premolars to the mental foramen in men and women pDistribution of the average distance from the end of the root of the second premolar of the right mandible to the mental foramen in men and women Average 5 left Gender Chart 4. Distribution of the average distance from the end of the root of the second premolar of the left mandible to the mental foramen in men and women as seen in Table2: Apices and the Mental Foramen by CBCT Imaging according to Sex in Patients Referred to Dental School of Ahvaz Jundishapur University of Medical Science in 2020-2021 (Persian)].Jundishapur Scientific Medical Journal.2023; 22(4):412-424.10.32592/JSMJ.22.3.412https://doi.org/10.32592/JSMJ.22.3.412Use your device to scan and read the article online ‫اهواز‬ ‫شاپور‬ ‫جندی‬ ‫دندانپزشکی‬ ‫دانشکده‬ ‫رادیولوژی‬ ‫بخش‬ ‫جهت‬ ‫ها‬ ‫داده‬ ‫نهایت‬ ‫در‬ ‫شد.‬ ‫وارزیابی‬ ‫ثبت‬ ‫کمک‬ ‫به‬ ‫مرد،‬ ‫و‬ ‫زن‬ ‫جنس‬ ‫در‬ ‫منتال‬ ‫فورامن‬ ‫تا‬ ‫مندیبل‬ ‫پرمولر‬ ‫های‬ ‫دندان‬ ‫ریشه‬ ‫انتهای‬ ‫فاصله‬ ‫تفاوت‬ ‫بررسی‬ ‫افزار‬ ‫نرم‬
Citation Alavinezhad P, Kavoosi M A, Beitsayah M. [Differences in Distance between Mandibular Premolars Root