The location of mental nerve has been extensively studied anatomically and radiographically. This systematic review aims to summarize the common location of mental foramen (MF) as well as its anatomical variation, the accessory mental foramen (AMF). The PubMed and Google Scholar databases were both searched for the available study until Jan 2020. The database search yield 2766 study of which 47 were included in this study according to the inclusion criteria. The study concludes that in general the position of the mental foramen is between area distal to the first premolar root apex and the long axis of the apex of second premolar in 82% to 90% according to panoramic and CBCT studies reported until 2020 respectively. Importantly, AMF incident has been found in 8.3% of the population, according the all of the CBCT studies included in this systematic review.

Introduction: The mental nerve, a branch of the trigeminal nerve’s mandibular division provides sensory innervation to the lower lip, dentition, gingiva, and mucosa. Knowing the exact location of the mental foramen along with its accompanying structures including possible accessory foramina, and the anterior loop is crucial for avoiding surgical complications. Advancements in Cone Beam Computed Tomography (CBCT) have provided unparalleled insights into these anatomical structures. This study uses the CBCT modality to investigate the anatomical variations of the mental foramen and anterior loop within a United States dental school patient population, aiming to improve surgical outcomes and patient safety. Materials and Methods: A retrospective cross-sectional analysis was conducted on 1,006 CBCT scans from patients at Temple University's Dental School between January 2020 and July 2022. Inclusion criteria encompassed patients aged 18 years and above who underwent pre-operative CBCT scans, with exclusions for maxillary-only scans and images lacking crucial mandibular structures. A total of 558 scans met these criteria and were analyzed. Data collected included patient demographics noting the location of the mental foramen, presence of accessory foramina, presence of the anterior loop and the length of the anterior loop for both the right and left side of the mandible. Results: The total number of scans included in the study was 558. The mean age of the patients from whom the data was collected was 54.95. Of the total subjects 185 were older than 50, and 373 were younger than 50 years of age. 311 of the subjects were female and 247 were male. The race distribution is as follows: 263 Caucasians, 170 African Americans, 72 Hispanics, and 53 Asians. As for the dentition status: 454 individuals had partial dentition, 79 had complete dentition, and 25 were edentulous. The study revealed a 0.05% occurrence of accessory mental foramina and a predominant location of the mental foramen apical to the second premolar, consistent across racial groups but not significantly influenced by age or gender. The anterior loop was present in 56.5% of scans, with an average length of 3.3 mm. Notably, the distance between the anterior loop and the mental foramen correlated significantly, suggesting potential surgical implications. Discussion: The findings highlight significant anatomical variability, challenging the reliability of traditional anatomical landmarks in surgical planning. The presence of the anterior loop and its variable length underscores the importance of individualized CBCT analysis before dental implant placement. Search for comparison within existing literature indicates a lower prevalence of accessory mental foramina in our study, suggesting population-specific anatomical variations. Conclusion: This study underscores the critical role of CBCT in identifying the anatomical nuances of the mental foramen and anterior loop, advocating for its routine use in pre-surgical planning for dental implants. The variability observed in these structures, even within the same patient, emphasizes the need for personalized surgical approaches to mitigate risks and enhance patient care. Future research should aim to expand the sample size and diversity to validate these findings further and explore their clinical implications. / Oral Biology

INTRODUCTION: Many studies have used different diagnostic methods to detect and measure the mental loop. Due to different criteria used and dissimilar diagnostic techniques diverse results were found in these studies. Understanding anatomical structures are crucial for planning and placing dental implants. Implant surgeons should be familiar with anatomical variations that they may encounter. METHODS: CBCTs of twenty male and twenty female patients were selected and categorized into four groups; male and female groups aged (18-44) and male and female groups aged (45-65). SIMPLANT Pro 17.01 software was used to determine the shape and the extension of the mental loop. Data was collected and analyzed for statistical significance to determine the association between CBCT findings and the patient's gender and age. RESULTS: The extension of the anterior loop of the metal nerve in this study ranged between 0 – 3.17mm. The mean of the loop was 1.25mm. The mental loops mean extension in males was 1.25mm. The mental loops mean extension in females was 1.23mm. The mental loops mean extension in elders was 1.19mm. The mental loops mean extension in younger group was 1.28mm. Subjects tend to have more curved mental loops compared to straight loops regardless the gender and/ or age group. CONCLUSION: In this study no association found between the shape and the extension of the mental loop with subjects age and gender. Measuring the extension of the mental loop should be mandatory for each individual to avoid injuries during implant placement in the interforaminal region.