Abstract
Background: The sella turcica is a structure readily seen on lateral cephalograms and sella point is routinely traced for various cephalometric analyses. The aim of the present study was to evaluate the morphometric variation in size and shape of sella turcica via lateral cephalogram. The objectives were to introduce a novel sella turcica index (STI) and assess its reliability that could be helpful in gender determination. Materials and Methods: A total of 80 lateral cephalograms of the patients of age group 10–30 years were included for the study. The morphological variations of the sella turcica was done based on the classification given by Axelsson et al. (2004). The length, depth and perimeter of the sella turcica was measured and STI derived and calculated. The data was further subjected to discriminant analysis to validate the gender outcome. Reliability of the novel index was determined by calculating the sensitivity and specificity. Results: The overall most common morphological type of sella turcica was Type A (56.25%) followed by Type B (18.75%) and Type E (13.75%). The mean perimeter and depth of sella turcica was higher in females whereas the mean length of sella turcica was higher in males. The mean STI was higher in males and statistically highly significant. The sensitivity and specificity of this index was 72.5% and 90% respectively. Conclusion: A significant relationship was observed between the morphometric measurements of sella turcica and gender. STI could be of great help as a reliable tool for personal identification in forensic sciences.
Supplementary Information
The online version contains supplementary material available at 10.1007/s12070-023-04082-9.
Keywords: Discriminant analysis, Lateral cephalogram, Morphology, Perimeter, Sella turcica
Introduction
Sella turcica is an important anatomical structure in radiographic analysis of the neurocranial and craniofacial complex. It can be well appreciated on lateral cephalometric radiographs and commonly traced for cephalometric analysis [1]. Sella turcica is a saddle-shaped concavity in the body of sphenoid bone situated in the middle cranial fossa of the skull. Sella turcica gets its name from Turkish language because of its similarity to the Turkish saddle. The depression in saddle is noted as pituitary fossa or hypophyseal fossa wherein the pituitary gland is situated [2].
Any deviation from the normal size and shape of the sella turcica due to its malformation may be implicated in an undetected underlying disease and can be an indication of a pathological condition of the gland. It may be attributed to the disturbance in regulation of secretion of glandular hormones. Some patients with an abnormal sella turcica are suffering from several underlying diseases, intrasellar pituitary primary tumors, hypopituitarism, or syndromes like Williams or Sheehan’s syndrome. This issue further emphasizes the significance of diagnosis of patients suffering from these conditions by noticing the abnormal shape and size of the sella turcica [3]. The size of sella turcica assessed from radiographs can be either linear or determined by various methods of area and volume measurements. It typically ranges from 4 to 12 mm for the vertical and 5 to 16 mm for the anteroposterior dimension [4, 5]. The average perimeter of sella turcica was suggested to be 30.4-31.3 mm according to Al-cablany Ebrahem Hezam et al. (2020) [6].
Materials and Methods
Aims
Evaluate the morphometric variation in size of the sella turcica in Jharkhand population.
Evaluate the morphometric variation in the shape of sella turcica in Jharkhand population.
Objectives
Introduce a novel sella turcica index.
Reliability of the index which could be helpful in gender discrimination.
The present study was a retrospective study done from the archived images of the patients undergoing lateral cephalograms in the department of Oral Medicine and Radiology, Dental Institute, RIMS. This study was undertaken after approval from the Institutional Ethical Committee, RIMS, Ranchi. (Memo no 14, IEC, RIMS dated 03/02/2022). A total of 80 lateral cephalograms of patients ranging in age from 10 to 30 years were selected for the study.
Inclusion Criteria
Lateral cephalograms with good visibility of all cephalometric structures including the sella turcica were included in the study.
Exclusion Criteria
Individuals with congenital defects in the craniofacial region such as clefts and malformations, history of craniofacial fractures and patients suffering from disorders of bone, nutritional deficiencies and endocrinal disturbances were excluded from the study.
Digital lateral cephalometric radiographs were taken by using ORTHOPHOS XG machine with a tube voltage of 73 kV, tube current of 15 mA and exposure time of 9.4s with proper radiation measures. The morphology and all the measurements were done using Sidexis next generation software. (version 2.5, Sirona, Germany)
Shape of the Sella turcica
For assessment of the morphological eccentricities of the sella turcica, the classification given by Axelsson et al. (2004) was used. There were five variations described in the morphology of sella turcica apart from the normal morphology. The six morphological variations considered were as follows -.
Type A: normal,
Type B: oblique anterior wall,
Type C: sella turcica bridging,
Type D: double contour of the floor,
Type E: irregularity (notching) in the posterior part of the dorsum sellae,
Type F: pyramidal shape of the dorsum sellae [7].
Size of the Sella turcica
The length (l) was measured as the linear distance from the superior most point on the tuberculum sella to the tip of the dorsum sella. The depth (d) was measured as a line perpendicular from the line joining tuberculum sella and dorsum sella to the inferior most point on the floor. The perimeter (p) of the sella turcica was calculated by considering 5 points on the sella turcica as described in Fig. 1.
Fig. 1.
(A) Digital lateral cephalogram showing sella turcica, (B) measurement of length and depth, (C) measurement of the perimeter of the sella turcica
Hence, a novel sella turcica index (STI) was derived and being calculated as:
Sella Turcica Index (STI) = Perimeter (p)/Depth (d) - Perimeter (p)/ Length (l)
Statistical Analysis
All the data collected were written in a proforma specially designed for the study. All the observations were performed by two investigators to eliminate any bias and average calculated. The overall morphological variations were calculated in terms of frequency and compared gender wise. The mean values and standard deviation of the various parameters such as length, depth and perimeters were calculated and compared with the help of student’s t-test and p value obtained. Further, the data was also subjected to discriminant analysis to validate the gender outcome. Reliability of this novel index was determined by calculating the sensitivity and specificity. Statistical analysis was done with the help of SPSS (Statistical Package for the Social Sciences) software version 22.0. P value was considered significant at < 0.05.
Results
A total of 80 subjects (40 males and 40 females) were included in the study. The mean age was 19.61 years for females and 18.32 years for males. The overall most common morphological type of sella turcica was Type A (56.25%) followed by Type B (18.75%), Type E (13.75%), Type C (10%), Type D (1.25%) and Type F (0%). In females, the most common morphological type of sella turcica was Type A(45%) followed by type B(20%) type C(12.5%) and type E(9%). In contrast, Type A was 67.5%, type B (17.5%), type C (7.5%), type D 2.5% and type E (9%) in males. [Table 1]
Table 1.
Variations in the morphological types of sella turcica
| Types | Total | Percentage (%) | Female | Percentage (%) | Male | Percentage (%) |
|---|---|---|---|---|---|---|
| Type A | 45 | 56.25 | 18 | 45% | 27 | 67.5% |
| Type B | 15 | 18.75 | 8 | 20 | 7 | 17.5% |
| Type C | 8 | 10 | 5 | 12.5 | 3 | 7.5 |
| Type D | 1 | 1.25 | 0 | 0 | 1 | 2.5 |
| Type E | 11 | 13.75 | 9 | 22.5 | 2 | 5 |
| Type F | 0 | 0 | 0 | 0 | 0 | 0 |
The mean perimeter of sella turcica was slightly higher in females (31.97) when compared to males (31.1) which was statistically non-significant with p-value of 0.18. The mean length of sella turcica was higher in males (11.52) when compared to females (10.20) which was statistically significant with p value of < 0.005. The mean depth of sella turcica was higher in females (9.02) when compared to males (6.51) which was statistically significant with p value of < 0.001. The mean STI was higher in males (2.18) when compared to females (0.38) which was statistically highly significant with p-value of < 0.00001.[Table 2].
Table 2.
Calculation of sella turcica index
| Group | p/d | p/l | Sella turcica index (p/d – p/l) | p-value |
|---|---|---|---|---|
| Females | 3.57 | 3.19 | 0.38 | < 0.00001** |
| Males | 4.76 | 2.72 | 2.18 |
** p-value statistically significant
Normal distribution curve showed 68.27% and 95.45% sample population had STI between − 0.32 and 1.08 and − 1.02 to 1.78 respectively in females. In males, it was shown that 68.27% and 95.45% sample population had STI between 0.98 and 3.38 and − 0.18 to 4.58 respectively. [Table 3; Fig. 2]
Table 3.
Intra-group variation of sella turcica index
| Group | Mean | Maximum | Minimum | Standard deviation | Mean ± SD1 (68.27% of population) |
Mean ± SD2 (95.45% of population) |
|---|---|---|---|---|---|---|
| Females | 0.38 | 2.94 | -1.12 | 0.70 | 1.08 to -0.32 | 1.78 to -1.02 |
| Males | 2.18 | 5.60 | 0.21 | 1.2 | 3.38 to 0.98 | 4.58 to -0.18 |
Fig. 2.
Normal distribution curve showing comparison of sella turcica index in males and females
Discriminant analysis was done using gender as a dependent variable and STI as an independent variable which showed 65 out of 80 results had positive outcomes. The sensitivity and specificity of this novel STI was 72.5% and 90% respectively.
Discussion
The morphological assessment of sella turcica is a measuring tool for assessing the pituitary gland because the development of sella turcica is directly related to the development of the pituitary gland [8]. The dimensions of the sella turcica measured under pathological conditions can be used to roughly determine the size of the pituitary gland because pituitary pathology ultimately affects the size of the sella turcica. The empty sella syndrome, which is the state of a reduced or flattened pituitary gland, is one of the clinical implications of the sella turcica. The most frequent intracranial neoplasms are pituitary tumors, which might occasionally show as silent subclinical tumors that are discovered by chance during cephalograms [9].
In 1922, Gorden and Bell classified sella turcica into three shapes: round, oval, and flat/saucer-shaped after examining radiographs of healthy children between the ages of 1 and 12. The majority of participants had circular or oval-shaped sella turcica, leading researchers to the conclusion that not all cases could be classified in such a broad three-way manner [10]. Further, Axelsson et al. (2004) conducted a study in Norway in 6–21 years old males and females and demonstrated that the normal variety of sella turcica was found in two/third of the subjects while the remaining subjects indicated dysmorphological appearance [7]. According to Islam M. et al. (2017), 31% of the individuals had different variants of sella turcica, whereas 69% had the typical variety [11]. Similarly, the normal morphology (Type A) was found to be in the majority of the population (56.25%) in the current study. Equivalence was observed when it was subcategorized according to gender.
Regarding the impact of age, it is generally agreed that the sella turcica grows more slowly during early adulthood and subsequently stops growing altogether after the first few years of existence. Silverman investigated 320 subjects from 1 month to 18 years of age and reported that sella turcica was larger in males than in females except during puberty which occurred about 2 years earlier and was more pronounced in females than in males [12]. Axelsson et al. (2003) examined the size of Norwegian males and girls longitudinally with normal facial appearance and occlusion. Males and females had comparable depths and diameters, but males had longer body [13]. A study done on Saudi sample suggested while measuring sella turcica size, the height of the gland was usually 2 mm shorter than the actual depth of the sella (the gland does not fill the whole volume of the sella turcica), and that this should be taken into consideration during measurements [14]. In our study, the mean length of sella turcica was higher in males whereas the mean depth was higher in females which was statistically significant suggesting obvious gender variances.
The perimeter of the sella turcica was observed in very few studies. Al-cablany Ebrahem Hezam et al. (2020) hypothesized that the sella turcica’s typical perimeter ranged between 30.4 and 31.3 mm [6]. The mean sella turcica perimeter in the current study was within the same range and slightly higher in females (31.97) than in males (31.1), which was statistically insignificant.
A novel STI was further derived in the current study to validate the reliability of the various parameters of the sella turcica. The mean STI was higher in males (2.18) when compared to females (0.38) which was statistically highly significant. To authenticate this novel index, discriminant analysis was performed which showed 65 positive outcomes out of 80 subjects. This is the first study ever conducted on the Indian population with STI. Moreover, studies should be performed on a larger scale to validate this novel index and prove its applicability in the field of forensic odontology.
Conclusion
Lateral cephalograms are one of the most common radiographs used to assess craniofacial morphology but the sella turcica region is often overlooked. A thorough screening of cephalogram by a trained oral physician could prevent such life‑threatening conditions. The innovation of this novel sella turcica index could also be of great help as a reliable tool for gender determination and personal identification in forensic sciences.
Electronic Supplementary Material
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Acknowledgements
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Funding
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Declarations
Conflict of Interest
The authors declare that there is no conflict of interest.
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