Age estimation using cephalometric analysis of hyoid bone: A radiological study

INTRODUCTION

Identification of a person relies on three general factors: Sex, age, and stature. The estimation of age holds significant importance for both living and deceased individuals.^[1,2] Age estimation finds applications in forensic human identification, clinical practice, research, and legal proceedings. Various methods are employed for age estimation, including visual, morphological, radiological, and biochemical approaches. The radiological method is commonly preferred due to its nondestructive nature and simplicity.^[3]

In the field of Dentistry, calculating the chronological age is necessary for orthodontic treatment planning. Since there can be individual variations in growth duration and velocity, age criteria play a key role in determining treatment options, the appropriate timing to initiate treatment, establishing prognosis, and devising a retention strategy.^[4]

During an individual’s growth, bones undergo a series of changes that follow a chronological pattern, facilitating age estimation. Among these bones, the hyoid, which is a solitary floating bone in the head and neck region holds significant importance in both age estimation and orthodontic treatment planning.^[5-7] The structure and positioning of the hyoid bone in the head and neck region can influence the approaches and methods employed in orthodontic treatment.^[8-11]

The hyoid is linked to various intraoral and extraoral structures, including the tongue and mandible, through muscles. They play a crucial role in orthodontic treatment planning.^[11,12] Furthermore, the hyoid bone is also considered important in assessing oral frailty, which is an early indicator of orofacial muscle weakness. Oral frailty can influence dental treatment and swallowing. As a result of the anatomical and physiological connections, any pathology or dimensional change in the connected structures directly influences the positioning of the hyoid bone.^[12,13]

Measuring the precise position of the hyoid bone can be challenging due to its high variability, even within the same individual and position. To address this issue, the hyoid bone triangle analysis was developed. The results obtained from the hyoid triangle analysis in cephalometric radiographs, as established by Bibby and Preston, are considered more accurate compared to using other reference planes.^[14]

The previous studies have focused on establishing the relationship between the hyoid bone and various growth patterns in individuals with different types of malocclusions.^[13-18] Since cephalometric radiographs are commonly used for age estimation^[13,19] and hyoid bone triangle analysis provides an accurate reference plane, the primary aim of this study is to estimate the chronological age of patients by employing hyoid bone triangle analysis using cephalometric radiographs. Based on our understanding, the present study presents a novel approach to estimate age that offers the advantage of minimizing radiation exposure by eliminating the requirement for additional radiographs like hand-wrist radiographs.

MATERIAL AND METHODS

This retrospective study obtained ethical approval from the Institutional Ethical Committee (Ref no: IHEC-I/0733/22). Lateral cephalograms from the Department of Orthodontics and Dentofacial Orthopedics archives spanning 10 years (2011–2020) were used for the study. All cephalograms were taken by a qualified radiographer under standardized conditions, ensuring that the F-H reference plane and the floor were parallel to each other. The same cephalogram was used for all radiographs, and the radiographic technique and exposure parameters were standardized.

The cephalograms were divided by gender, and inclusion criteria included proper positioning of subjects in the X-rays, absence of gross abnormalities, clarity of the X-ray, and retrieval of lateral cephalograms from the study period. The sample size was determined to be 234, calculated with a power (1-β) of 99%, a level of significance of 5%, and a 1% margin of error.

The lateral cephalograms were traced by the same operator using an X-ray illuminator. An independent examiner cross-checked all anatomical landmarks and tracings. Selected anatomical landmarks were used to trace planes, lines, and angles, including gnathion (Gn), the most anterior and lowermost point on the bony outline of the mandible; retrognathism (RGn), the most posterior and lowermost point on the bony outline of the mandible; hyoidale (H), the anterior superior most point on the body of the hyoid; C3 (lowermost and anterior point on the third cervical vertebrae), and the (Frankfort horizontal plane (FH plane) connecting Porion and Orbitale) [Figure 1].

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Figure 1:

Ref points traced: C3-H, H-RGn, and C-RGn forming a hyoid bone triangle. R-Gn: Retro-gnathion, H: Hyoidale.

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The hyoid triangle was traced using the above landmarks, and the measurements of the hyoid bone triangle (C3-H, H-R-Gn, and C3-R-Gn) were analyzed and included in the statistical analysis.

The measured data were recorded and analyzed using the Statistical Package for the Social Sciences Version 26 software (IBM, Chicago). One-way analysis of variance and linear regression analysis were performed, with statistical significance at P < 0.05.

RESULTS

From the measurement, the mean value of the following parameters, C3-H and H-RGn, was 35.76 mm ± 0.44 mm and 40.33 mm ± 0.54 mm. Among all the dimensions of the hyoid bone triangle (C3-H, H-R-Gn, and C-R-Gn), the distance between cervical vertebrae (C3) to hyoid bone (H) was found to be statistically significant for both age estimation and gender prediction, and the mean value of C3-H for females was recorded to be 3.57 ± 0.43 and for males 3.58 ± 0.43 [Figure 2]. Tables 1 and 2 depict the sample size, mean value, and standard deviation (SD) of C3-H and H-R-Gn. This study illustrates the mean and SD of 35.76 mm ± 0.44 mm and 40.33 mm ± 0.54 mm. The mean value of C3-H for females was recorded to be 3.57 ± 0.43, and for males, 3.58 ± 0.43. The present research confirmed a correlation between the Gonial angle of males and females, which were statistically significant. Furthermore, there is a satisfactory correlation between real age and estimated age (r² = 0.146) [Figure 3, Tables 3 and 4].

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Figure 2:

Graphical representation of mean values of hyoid bone triangle (C3-H, H-R-Gn, and C-RGn), dimensions across age groups 13–24 for males and females. R-Gn: Retro-gnathion, H: Hyoidale.

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Figure 3:

Residual plot across C3-H and gender. H: Hyoidale.

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DISCUSSION

This study aimed to determine chronological age through hyoid bone triangle analysis using cephalometric landmarks. The specific objectives were to record the basic dimensions of the hyoid bone triangle for different age groups and to compare these measurements between genders. The hyoid bone holds significance in both dentistry and forensics. Forensic experts face challenges in determining unknown facts but overcome them with innovative methodologies. While modern technologies exist, their applicability may be limited in certain situations, making non-destructive radiological methods with simpler techniques preferable. Age estimation using lateral cephalograms is commonly employed in dentistry. This study conducted a cephalometric analysis of the hyoid using hyoid bone triangle analysis to estimate age group and attempt gender identity based on it.

Despite the fact that the location of the hyoid bone is under the guidance of even small movements of the head and surrounding structures, standardization was maintained throughout the study. The H-R-Gn specification of the hyoid bone triangle is affected by the variation in the mandibular dimensions. The C3-H component showed statistical significance (P < 0.001) for both age and gender estimation. While H-R-Gn had statistically significant results for gender determination (P < 0.05), the regression analysis yielded a weak R-value (R = 0.019).

Regarding age estimation, H-R-Gn values were not significant, but the mean values of H-RGn in males remained constant above 18 years, while the same trend was observed for C3-H values in females. This could be attributed to the posterior and superior positioning of the hyoid bone in females compared to males, showing variations among different skeletal classes. An interesting finding was that there is a downward displacement of the hyoid bone with age.^[20]

The overall mean parameters of the hyoid triangle were higher compared to the previous studies.^[20,21] The overall mean value of the parameters selected is greater than the Pakistani populations on compared with their values. This shows that in our study population, the hyoid bone is positioned posterior and downward. The present study was conducted in the Indian state of Tamil Nadu. Further studies with larger sample sizes and expanded parameters should be conducted to investigate the effects of age, sex, and skeletal patterns on the position of the hyoid bone. The predictability of two-dimensional cephalograms for assessment of age and gender may not be very precise. With the 3D images, more predictable results can be obtained.

CONCLUSION

The study determined that the mean values of parameters used to assess the position of the hyoid bone within the study population are 35.76 mm ± 0.44 mm (C3-H) and 40.33 mm ± 0.54 mm (H-RGn). The hyoid bone is positioned downward and posterior in the studied age group. This criterion has the potential to hold significance in age determination for Medical jurisprudence, thus aiding legal investigations.

The findings from this study have implications for orthodontic treatment planning, particularly in cases involving dental and skeletal malocclusions.

Gaining a deeper understanding of the variation of the hyoid bone location among different gender and age groups can assist in diagnosing and predicting illnesses such as obstructive sleep apnea, which predominantly affects middle-aged males.