Downloaded from http://journals.lww.com/jcraniofacialsurgery by BhDMf5ePHKbH4TTImqenVBZZxeh5YHRL3OIOk14Fov2sRZC5AMYxzF7T0LChd6lSFFHq5HTyUTo= on 10/23/2020 Copyright © 2020 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited. Morphometric Development of the Mandible in Fetal Cadavers Yadigar Kastamoni, PhD,  Ahmet Dursun, MD, PhD,  Onur Can Sanli, MSc,  Neslihan Yuzbasioglu, PhD, y and Soner Albay, MD  Purpose: The aim of this study is to present reliable data by measuring the morphometric properties of the mandible in the fetal period. Methods: A study was performed on mandibles of 35 fetuses (18 male fetuses and 17 female fetuses), aged between 21 and 40 weeks of gestation. Fetuses were examined in 3 groups according to their developmental stages: 2nd trimester, 3rd trimester, and full-term. Morphometric measurements were performed for both the right and left sides of each mandible. The measurements of the mental foramen were performed using a digital caliper, and other measurements were performed using the ImageJ program. The data obtained were analyzed using the SPSS 20 for Windows program. Results: There was no significant gender difference for all parameters. When the parameters were compared by the trimesters, no significant difference was determined in the 2nd trimester - 3rd trimester, 3rd trimester-full-term, and second trimester - full-term comparisons of the angle of the mandible, and there was a significant difference in all other parameters (P < 0.05). According to the trimesters, all parameters, except the angle of the mandible, increased naturally with the development of the mandible. It was observed that the angle of the mandible decreased from the 2nd trimester to the 3rd trimester and increased from the 3rd trimester to the full term. When the right and left measurements were compared, no significant difference was found for all parameters in both general and trimester groups. Conclusion: The present study includes fetal mandibular parameters that have not been reported elsewhere. It is thought that the obtained data will contribute to the determination of anomalies, pathologies, and variations. Key Words: angle of the mandible, ImageJ, mental foramen, pathologies, trimester (J Craniofac Surg 2020;31: 2036–2039) T he mandible is the largest, strongest, and the only movable bone of the skull. 1,2 The mandible, which forms the lower part of the facial skeleton, consists of the body of the mandible, where teeth are present and which extends horizontally, and the 2 rami of the mandible extending vertically at the back. 1 The mandible is ossified from 2 centers around the mental foramen on both sides. Ossification starts in the 6th month of the intrauterine life in the membrane surrounding the outer side of the ventral part of Meckel cartilage. In the 10th month, the lower and posterior parts of Meckel cartilage in the incisor teeth are covered with the membranous bone. Afterward, secondary ossifi- cation centers are observed. These secondary ossification centers are not separate ossification centers and are surrounded by the membranous bone and absorbed. The inner edge of the alveoli is usually ossified from a separate center. 1 At birth, the mandible is in the form of 2 parts connected to each other by fibrous tissue. These 2 parts are ossified in the first year, and the mandible becomes a single part. The place of the junction is called the mandibular symphysis. The mandibular canal is present inside the body of the mandible. The mandibular canal starts from the mandibular foramen located on the inner surface of the ramus of the mandible and ends in the mental foramen located on the outer surface just below the central incisor. The angle between the ramus and the body of the mandible is the angle of the mandible and is approximately 1358 to 1408 at birth. 1,3 There are 2 protrusions at the upper end of the ramus of the mandible, the coronoid process and the condylar process. The top of the condylar process is called the head of the mandible, and it forms a joint with the temporal bone. 1 Knowing normal mandibular dimensions is important for dem- onstrating fetal tooth genesis during the prenatal period because it is said that the mandibular parameters may change in case of the presence of genetic syndromes and chromosomal anomalies, and, therefore, they may help in the diagnosis of these conditions in the fetal period. 4,5 Mandibular fractures are the most common facial fractures that are uncommon in pediatric patients when compared to adults. They mostly occur due to a high-impact trauma. 6,7 Mandibular condyle fractures are common and account for 25% to 40% of all mandibular fractures. Both closed treatment (closed reduction, rigid or elastic intermaxillary fixation, physiotherapy) and open surgery (open reduction and internal fixation) have been used for managing mandibular condyle fractures. 8 Although conservative treatment is recommended in children, it is necessary to use open reduction internal fixation in some cases, such as mandibular angle fractures and condyle fractures. 6–8 Furthermore, prominent mandibular angle, mandibular malformation, etc cases are usually treated with mandibular split osteotomy. 9 The obtained data may be helpful in surgical interventions on the mandible in case of facial fractures and mandibular malformation in premature infants and newborns. From the  Department of Anatomy, Faculty of Medicine, Suleyman Demirel University, Isparta; and y Department of Anatomy, Faculty of Medicine, Medipol University, Istanbul, Turkey. Received November 8, 2019. Accepted for publication April 13, 2020. Address correspondence and reprint requests to Onur Can Sanli, MSc, Department of Anatomy, Faculty of Medicine, Suleyman Demirel University, East Campus, 32260 Isparta, Turkey; E-mail: fztonurcansanli@gmail.com This study was presented as an oral presentation in the International Mediterranean Anatomy Congress and to the 19th National Anatomy Congress, 6 to 9 September 2018, in Konya, Turkey. The authors report no conflicts of interest. Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.jcraniofa- cialsurgery.com). Copyright # 2020 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000006670 ANATOMICAL STUDY 2036 The Journal of Craniofacial Surgery  Volume 31, Number 7, October 2020