A Review on Anatomical Variations of Mental Foramen (Number, Location, Shape, Symmetry, Direction and Size)

Mental foramen is located on the anterior aspect of the mandible that permits the terminal branch of the inferior alveolar nerve and blood vessels to exit. The anatomical variations of mental foramen are of considerable importance in local anesthesia, treatment of the fractures in the parasymphysis area, orthognatic surgeries, implant placement, etc. Regarding the importance of mental foramen in dentistry (from local anesthesia to invasive surgical procedures), this study intends to review the anatomical variations of mental foramen in this study. Absence of mental foramen is rare. On the other hand, prevalence of accessory mental foramen has been estimated lower than 15% in the most studies. The position of mental foramen is normally between first and second premolar teeth or under second premolar tooth in different ethnic groups and bilateral symmetry exists in regard with location in most cases. In most studies, the ratio of distance from mental foramen to symphysis to distance from symphysis to posterior border of ramus has been reported about 1/3.5 to 1/3. Mental foramen is oval or circular in shape and its most common direction is usually posterosuperior. Its size in different studies has been estimated about 2 to 5 millimeters and asymmetry in size is possible on both sides of mandible. Due to variations of mental foramen between various ethnic groups and even different individuals in the same ethnic group, using advanced imaging techniques such as CBCT is recommended in order to gain detailed knowledge of anatomy and morphology of mental foramen before applying invasive surgeries

Evaluation the Prevalence of Impacted Teeth in Patients Referred to Department of Oral and Maxillofacial Radiology of Yazd Dental School in years 1392-1394

Introduction: Tooth impaction is a common anomaly. Several local and systemic factors may result in tooth impaction. Among the permanent dentition third molar, maxillary canine, maxillary and mandibular premolar and maxillary central incisors have the most probability of impaction. The aim of this study was to determine the prevalence of impacted teeth in the patients referred to Yazd Dental School in 1392 to 1394. Methods: In this retrospective study, 600 digital panoramic radiographies of the patients over 15 years old were examined. The patients with dent of axial abnormalities, other syndromes or particular pathology, edentulous and traumatized patients were extracted from the study. Data were statistically analyzed using SPSS software (version 22.0 for Windows, Chicago, IL, USA), Chi-square and Fisher's exact tests. Results: Out of total 600 patients were examined, 99 patients (16.5%) presented with at least one impacted tooth. Mandibular third molars were the most prevalent (52.26 %) impacted teeth, followed by impacted maxillary third molar (27.7%), maxillary canine (13.8%) and mandibular canine (4.86%). The highest prevalence of tooth impaction was seen in 22-30 years age group. There was no statistically significant difference between tooth impaction and gender (p-value=0.91). Conclusion: Tooth impaction has a relatively high prevalence in Yazd  (16.5%). The highest prevalence of tooth impaction is seen in third molars followed by canine teeth of both jaws. So, in case of delayed eruption of canine teeth, radiographic examination is suggested to evaluation their impaction and applying proper managements