242 J Contemp Med Sci | Vol. 7, No. 4, July-August 2021: 242–246 Original Correlation Between Sphenoclivus Angle and Gnathic Angle with Age and Gender in Iranian Population using CT-Scan Gholamreza Hassanzadeh1,2, Ghazaleh Moshkdanian3, Morteza Gholaminejhad2, Mahnaz Poorhassan4, Babak Ebrahimi2, Reza Habibi5, Parichehr Pasbakhsh2, Tayebeh Rastegar2, Mahdad Abdi2, Yasmin Yazdooei6, Masoumeh Gity7,*, 1Department of Neuroscience and Addiction Studies, School of Advanced Technologies in medicine, Tehran University of Medical Sciences, Tehran, Iran. 2Department of Anatomy, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. 3Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran. 4Department of Anatomy, School of Medicine, Shahid beheshti University of Medical Sciences, Tehran, Iran. 5School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. 6Student Research Committee, Golestan University of Medical Sciences, Gorgan, Iran. 7Department of Radiology, Advanced Diagnostic and Interventional Radiology Research Center (ADIR), Breast Disease Research Center (BDRC), Imam Khomeini Complex Hospital, Tehran, Iran. *Correspondence to: Masoumeh Gity (Email: Imamhospital@tums.ac.ir). (Submitted: 02 April 2021 – Revised version received: 25 April 2021 – Accepted: 12 May 2021 – Published online: 26 August 2021) Introduction Anthropology is a science that makes it possible to quantify the dimensions of the human body in different societies.1–3 Cephalometry as an important branch of anthropology being employed to calculate the dimensions of the head and face used in archeology, surgery, forensic medicine, medical engi- neering, and industry.4–6 In the clinical set, anthropometric studies of the craniofacial diameters can help in the diagnosis and predicting disorders.7 The measurement of each index in the craniofacial complex such as sphenoclivus and gnathic angulation is highly required to identify differences in the skull, predict the future skeletal jaw pattern of a child, and determine the best way to achieve brain tumors.8 Cephalo- metric measurements can be taken using either a digital tracing method or a traditional method.9 But computed tomography (CT) joined the tools of the anthropologist improving the volume of information. It allows us to study the anatomical characteristics of external and internal structures that can’t be evaluated by the traditional morphometric instruments.5,10,11 However, so many studies have done to assess and com- pare the values of sphenoclivus angle and gnathic angle of each normal and abnormal skeletal group but very few studies are carried out to collect and group this information in Iran, and very rarely data exist to find the reliable relationship among the skeletal patterns of individuals.12 Thus in view of the fact, that the degree of its slope could also vary depending on the race or area in which the research was carried out.13 The present cephalometric study was con- ducted to find the difference in the values of sphenoclivus angle among Iranian adults and to explore the relationship between the sphenoclivus angle and gnathic angle. Materials and Methods This cross-sectional study was conducted from September 2018 to September 2019 in imaging centers affiliated with the Faculty of Medicine, Tehran University of Medical Sciences on 140 subjects (70 males and 70 females) aged between 18 to 60 years and the conscious consents were obtained. This study was approved by the ethics committee with the ID of IR.MED- ICINE.TUMS.REC.1398.602. Subjects were selected randomly. Abstract Objectives The aim of this study was to assess whether is a reliable correlation between the cranial and gnathic angulations in the Iranian population. Methods In a cross-sectional study, 140 patients of Tehran University of Medical Sciences hospitals (70 males and 70 females with an age range of 18–60 years) were selected. Sphenoclivus (cranial base) and gnathic angles were calculated for each case. Then, the data were analyzed using SPSS version 22. Results Statistical analysis showed a relationship between gnathic angle and female (P < 0.05), but no positive relationship was seen between sphenoclivus angle and gender. There was a significant relationship between sphenoclivus angle and age among men. No significant relationship was found between the gnathic and sphenoclivus angles. Conclusion Sphenoclivus angle has the closest link with age in males. The gnathic angle has also a positive relationship with females. Our findings suggest an independent growth pattern between the sphenoclivus angle and the gnathic angle. Keywords Anthropometry, sphenoclivus angle, cranial base angle, gnathic angle, cephalometric measurements ISSN 2413-0516 http://orcid.org/0000-0002-3056-4080 243J Contemp Med Sci | Vol. 7, No. 4, July-August 2021: 242–246 G. Hassanzadeh et al. Original Correlation between sphenoclivus angle and gnathic angle with age and gender in Iranian population using CT-scan Exclusion criteria were in the following: • People with skull bone abnormalities (congenital or acquired). • People with a history of trauma and skull fractures. • People with a history of maxillofacial surgery, including cosmetic surgery. • People of non-Iranian nationality. The parameters were measured in the whole scans based on the following definitions: Nasion: The middle point of the junction between the nasal bones with the frontal bone. Basion: The midpoint of the anterior margin of the foramen magnum. Prosthion: The lower edge of the maxillary alveolar process at the site of the anterior central teeth. Pituitary point: The anterior edge of the sellaturcica. Nasion-Basionline: It is a line connecting the nasion and basion. Basion-Prosthion line: It is a line connecting the basion and prosthion. Sphenoid plane: A plane that passes over the jugum of the sphenoid bone. Basion-Pituitary line: It is a line connecting the basion and pituitary point. Gnathic angle: It is an angle between the nasion-basion and basion-prosthion. Sphenoclivus angle (cranial base angle): It is an angle between the sphenoid plane and the basion- pituitary point. We first drew a line from the nasion to the basion and then a line from the basion to the prosthion. The angle between the two lines in terms of age and sex in a table and called it the gnathic angle (Fig. 1). In the next step, we measured the spheno- clivus angle, so that we consider a plane that passes over the jugum of the sphenoid to be the sphenoid plane. After that a line Fig. 1 Gnathic angle. This angle is between the Nasion-Basion line and the Nasion-Prosthion line. N: Nasion, B: Basion, Pr: Prosthion, NB: Nasion-Basion line, BPr: Basion-Prosthion line, Ga: Gnathic angle. Fig. 2 Sphenoclivus angle. This angle is between the Sphenoid plane and the Basion-Pituitary point line. B: Basion, Pp: Pituitary point, Sp: Sphenoid plane, BPp: Basion-Pituitary point, Sca: Sphenoclivus angle. Table 1. Comparing the anthropometric measurement of sphenoclivus angle and Gnathic angle between males and females in Iranian population Gender Male Female Mean SD Mean SD P-value Sphenoclivus angle 112.858 7.637 110.200 15.7096 0.192 Gnathic angle 36.915 3.5254 38.557 4.5550 0.023 from the basion to the pituitary point was drawn, now the angle between these two lines was named sphenoclivus angle (Fig. 2). Statistical Analysis The data were analyzed by SPSS software (Version 22). In this study, to describe quantitative variables, have been reported as mean ± standard deviation (SD). Frequency and percentages were reported to describe qualitative variables. To compare the quantitative variables, the T-test, and to compare the qualita- tive variables, the chi-square test was used. Pearson’s correla- tion coefficient test was used to obtain the correlations between quantitative variables. P < 0.05 was considered statis- tically significant. Results The average angle of the sphenoclivus in women was found 110.200 degrees and in men with a difference of about two degrees seen 112.858. According to the chi-square test, there was no significant difference between the two genders in the sphenoclivus angle (P = 0.192). Chi-square test analysis also showed that the anthropometric measurement of the gnathic angle was significantly higher for females than that in males (0.023) (Table 1). 244 J Contemp Med Sci | Vol. 7, No. 4, July-August 2021: 242–246 Correlation between sphenoclivus angle and gnathic angle with age and gender in Iranian population using CT-scan Original G. Hassanzadeh et al. those expected for his/her racial or ethnic group are discov- ered.9,14 Among all morphometric landmarks, the spheno- clivus angle serves as a reference structure to determine the skeletal type in the cephalometric analysis.15 In our study, the mean of the sphenoclivus angles was assessed 110.200° in females and 112.858° in males with no significant differences. Another study on Iranian showed the value of the cranial base angle in females is more than males.16 Although the presented data is in contrast with our findings in view of the fact that various Iranian ethnicities distribute all over the country, it is expectable to have different anthropo- metric features from city to city. Similar studies in India and Brazil also showed the wider sphenoclivus angle among females rather than males.17,18 Furthermore the differences between women and men, Table 4 shows the values of the cranial base angle can be found vary a lot in different places19–24 although, several authors declare that some anomalies such as herniation of the cere- bellum, Chiari malformations, malocclusion and craniocer- vical junction abnormality associated with the changes of this angle. Royo-Salvador affirmed that there is platybasia when the cranial base angle is more than 140°25 but some authors declared that the cranial base angle surpasses 140° and do not agree on the limit value for considering a skull platybasia.17 In agreement with these reports, a study in Finland showed the sphenoclivus in both normal and otosclerosis patient groups was the same and no significant changes in degree were men- tioned among Finnish people.26 More studies stated that the bigger sphenoclivus angles exist among the normal group in comparison with the Chiari patients group in turkey23 versus Brazilian revealed the more value sphenoclivus angle among the normal group.27 Although there was a slight difference between the mean values for the normal and patients groups but no significant differences between the two groups were reported. Moreover some anthropologists mentioned a posi- tive correlation between the slope of sphenoclivus angle and skin color so that this angle was calculated more than 125° and wider among the nonwhite population in comparison to that in white one.17 Therefore, the degree of the slope could be vary depending on the ethnicity, race, or area in which the research was carried out.13 So it is necessary to know in detail the ana- tomical structures to have a database bank for the comparison between normal and patient’s samples although our project only focused on the sphenoclivus angle in the normal population. Regarding the relation between age and the value of the sphenoclivus angle, we found a significant correlation between age and this angle in males so that the older men, the wider sphenoclivus angle value. In contrast with our results, some anthropologists declared that there was no relation between age and the value angle.17,18 Moreover, the consensus of dif- ferent authors proved that the sphenoclivus angle has a con- siderable influence upon the mandibular and maxilla position, thus it determines the skeletal jaw pattern of an individual. Although other researchers have obtained conflicting evi- dence, that there is no connection between the cranial base angle and the static position of the jaw.21,28 In spite of cranial base angle malformation, gnathic angle changes are presented as an index showing the presence of impairment in the sub nasal area of individuals. In compar- ison to the sphenoclivus angle, our results found no significant correlation between gnathic angle and age. Although, a posi- tive relationship between gnathic angle and gender was seen. A significant correlation was observed between spheno- clivus angle and age in the male group. And, no positive rela- tion was observed between gnathic angle and age in both genders (Table 2). According to the statistical test performed in this study, there was no significant difference between the sphenoclivus angle and the gnathic angle in both genders with a correlation coefficient of 0.005, it has predictive power (Table 3). The volume of sphenoclivus angle increases in males with age. By using the following formula, through entering the age in this formula (X), the size of the sphenoclivus angle can be predicted with a power of 0.25 (Fig. 3). y = (0.59 × x) _ 27.08 Discussion The main goal of cephalometry is to elevate the relationships between the person’s actual craniofacial morphology and Table 2. Correlation between sphenoclivus angle and gnathic angle with age in Iranian population Age Male Female Correlation coefficient (r) P- value Correlation coefficient (r) P- value Sphenoclivus angle 0.251 0.026 0.053 0.681 Gnathic angle 0.190 0.150 −0.097 0.499 Table 3. Correlation between the gnathic and sphenoclivus angle in Iranian population Sphenoclivus angle Male Female Correlation coefficient P- value Correlation coefficient P- value Gnathic angle 0.005 0.963 0.058 0. 702 Fig. 3 Correlation between age and sphenoclivus angle among men predicted by regression models. 245J Contemp Med Sci | Vol. 7, No. 4, July-August 2021: 242–246 G. Hassanzadeh et al. Original Correlation between sphenoclivus angle and gnathic angle with age and gender in Iranian population using CT-scan Table 4. Comparison of measured Sphenoclivus angle in different studies Place of study Tehran, Iran Isfahan, Iran Brazil India Turkey Kenya Spain Brazil USA Japan Romania USA Sample number 140 100 160 255 43 100 292 33 10 46 50 96 Reference number Present study 15 16 17 22 23 24 26 18 19 20 21 Female 110.2 131.72 115.56 131.42 – – – – – – – – Male 112.85 128.65 115.28 129.7 – – – – – – – – Mean – – – – 121 103–143 115–140 107–132 107–124 133.96 131.4 129.80 Remarkably, no reliable correlation was reported between sphenoclivus and gnathic angles. Our findings indicate the independent growth pattern between two important indexes of the craniofacial complex and vastly express the necessity for collecting the morphometric information not only in the dif- ferent populations but also in different genders separately. Conclusion In conclusion, with regard to this fact that many more studies are still needed on the measurement and analysis of craniofa- cial indexes. 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