Research Report 86 Indonesian Journal of Dental Medicine Volume 1 Issue 2 2018; 86-89 https://e-journal.unair.ac.id/IJDM Sex determination using gonial angle during growth spurt period: a direct examination Monica Hariemmy, Rizky Merdietio Boedi, Haryono Utomo, Mieke Sylvia Margaretha Department of Forensic Odontology, Faculty of Dental Medicine Universitas Airlangga Surabaya - Indonesia ABSTRACT Background: In forensic medicine and medicolegal, sex determination is an important step of an identifcation process. Parts of human skeleton that can be used for identifcation are cranium, pelvis, and mandible. There are several anthropometry tools in sex determination methods i.e shape of mandible, mental, gonial angle. Gonial angle in adults is an excellent tool for sex determination. However, bone density and masticatory force may change the value of gonial angle. Purpose: The objective of this study was to examine sex determination method using gonial angle in children during grow spurt period and external factors. Methods: There were 104 randomly selected subjects (51 boys and 53 girls) aged 7-12 years old. The subjects were grouped into prolonged sun exposure-hard diet (group A) and low sun exposure-soft diet (group B). The measurements were made using goniometer. Results: The mean of gonial angle of female children was greater than the male children. There was no signifcant difference between group A and B. Conclusion: Gonial angle can be used for sex determination in grow spurt period, and external factors did not affect sexual dimorphism. Keywords: sexual dimorphism, gonial angle, goniometer Correspondence: Mieke Sylvia Margaretha, Department of Forensic Odontology, Faculty of Dental Medicine Universitas Airlangga, Jl. Mayjend. Prof. Dr. Moestopo No. 47 Surabaya - Indonesia. Phone: +62315030255 Email: mieke-s-m-a-r@fkg.unair.ac.id INTRODUCTION Geographically, Indonesia is a country prone to natural disasters. In case of natural disaster, some deceased are found in a damaged or unrecognizable state. Therefore, sex determination is a crucial identifcation in forensic and medicolegal anthropology to determine the identity of the deceased. 1,2 Mandible is one of the valid parts of the skull for sex determination. Mandible is the strongest facial bone that curves horizontally, convex in the two ramus of mandibles, and ascends to the posterior end of the mandibular corpus. 3,4 Parts of the mandible that can be used in sex determination are the symphysis, the corpus, ramus, and the gonial angle (GA). 5-9 GA is formed from two lines, the inferior border of the mandibular corpus and the posterior border of the mandible ramus. 10 Physiologically, GA is blunt at birtha (175 o ) and shrinks in the second year (140 o ). In adults, the angle is between 110 o -120 o whereas in the old age group, gonial angles again increased to 140 o due to tooth loss. 11,12 GA growth can be directly measured using odonto pantomograph (OPG) and goniometer for sex determination. 10,13 However, in the event that mandibular skeleton is left, OPG cannot be used. Thus, a direct measurement method with a goniometer is needed. Growth spurt and external factors such as food texture and vitamin D from sun exposure can affect GA measurement. 14,15-17 The mandible development during growth spurt does not affect the GA. 2 In addition, after bone growth and development stops due to hormonal effects, the difference will appear clearly. 18 Therefore, internal and external factors must be considered. This study aimed to examine gonial angle method as sex determination tool of children during growth spurt and external factors. MATERIALS AND METHODS This was an observational analytic study with a cross sectional design. Ethical clearance was obtained from the Health Research Ethical Clearance Commission, Faculty of Dental Medicine, Universitas Airlangga 051/HRECC. FODM/II/2019. The participants of the study were children 7-12 years old totaling 104 subjects (51 male children and 53 female children). The participants were Kalijudan I Public Elementary School of Kalijudan area, Mulyorejo District and Muhammadiyah 4 Private Elementary School