Abstract The objective of this study was to test the accuracies of the Demirjian and the Willems dental age estimation methods using the seven left permanent mandibular teeth (excluding the third molar tooth) in children in southern Thailand. Digital panoramic radiographs of 240 Thai children (120 males and 120 females) aged from 8 to 15 years were chosen and separated into eight age groups. Dental age was assessed using the Demirjian and the Willems methods. Differences between the dental age and the chronological age were statistically evaluated by the Wilcoxon signed-rank test. The results showed that the Demirjian method overestimated age by 0.28 years and 0.24 years for males and females, respectively, while the Willems method underestimated age by −0.04 years and −0.23 years for males and females, respectively. Moreover, the mean absolute errors were 0.68 years in males and 0.56 years in females for the Demirjian method and 0.55 years in males and 0.60 years in females for the Willems method. In conclusion, the Willems method was more accurate for dental age estimation compared to the Demirjian method. However, both methods can be applied to estimate the age of children in southern Thailand since the mean error and mean absolute error values were less than one year.

Keywords: Dental age estimation, Demirjian method, Tooth developmental stage, Thai population, Willems method

Citation: Theerasopon, P., Charoemratrote, C. and Duangto, P., 2023. Age estimation using the demirjian and willems methods in a southern Thai population. Natural and Life Sciences Communications. 22(4): e2023058.

INTRODUCTION

Chronological age is an essential useful tool in clinical medicine, forensic sciences, criminal law, and in clinical dentistry such as oral diagnostic sciences, pediatric dentistry, and orthodontics (Schmeling et al., 2007). In cases of unknown age, it is necessary to perform age estimation. Although age determination can be done using several methods that incorporate parts of human growth and development, age estimation that uses stages of tooth development are widely used (Nik-Hussein et al., 2011; Ambarkova et al., 2014; Ye et al., 2014) since tooth development is easily classified and the accuracy of predictions are acceptable (Theerasopon et al., 2022). Dental structures are the strongest hard tissue in the human body and are mainly influenced by genetic factors, whereas environmental and nutritional factors play a lesser role in tooth development (Garn et al., 1965).

Dental age estimation can be done to estimate the chronological age of a living individual using the classified development stages of selected teeth from dental radiographs. Prediction equations from published studies of specific race or ethnicity can then be used to predict the possible chronological age of an unknown person. Due to the wide time frame of tooth development from embryo to adult, the available tools can be used to predict chronological age in both children and adults (Willems, 2001).

Demirjian et al. (1973) proposed dental age estimation using seven teeth at the left side of the mandible from the central incisor to the second molar. Tooth development was then classified into eight stages that ranged from formation of the cusp tip until complete root formation. Later, Willems et al. (2001) introduced a modified version of dental age estimation that also used seven teeth and defined tooth development stages according to the Demirjian et al. method but provided increased accuracy in specific races. However, several studies found that the accuracy of the Demirjian and the Willems methods varied within each racial and ethnic group (Lee et al., 2011; Nik-Hussein et al., 2011; Djukic et al., 2013; Ambarkova et al., 2014). Thus, most studies suggested testing the accuracy of each method in the appropriate population or suggested new equations if the published methods were found to be less accurate for a specific group of subjects. In Thailand, Duangto et al. (2016) developed a new method to estimate age using the same seven mandibular teeth and described the eight tooth development stages according to Demirjian et al. This equation was found to provide the highest accuracy compared to the Demirjian and the Willems methods. The age estimation equations of the Duangto et al. (2016) study were obtained from a population in northern Thailand. The objective of this study aimed to test the accuracy of the Demirjian and the Willems dental age estimation methods in a population of children and adolescents in southern Thailand. The tooth development stages were determined from the seven permanent mandibular teeth from the central incisor to the second molar using digital panoramic radiographs.

MATERIALS AND METHODS

This study was approved by the Human Research Ethics Committee of the Faculty of Dentistry, Prince of Songkla University, Songkhla, Thailand (EC6507-027). Digital panoramic radiographs were taken at the Dental Hospital of the Faculty of Dentistry, Prince of Songkla University, Songkhla, Thailand. All radiographs were generated using the GXDP-700 PANOREX + cone beam machine (Gendex Dental Systems, Hatfield, PA, USA) between 2015 and 2021. Digital panoramic radiographs of 240 Thai samples (120 males and 120 females) aged 8–15 years were randomly selected and divided into eight age groups (Table 1).

The chronological age of each subject was calculated by subtracting the date of the radiograph from the date of birth and was expressed as years with two decimal places. The exclusion criteria included non-Thai individuals, unclear radiograph, systemic disease, or jaw cyst or tumor. All radiographs were scored using the criteria of the Demirjian and the Willems dental age estimation methods (Demirjian et al., 1973; Willems et al., 2001). The chronological age was subtracted from the dental age. A positive value showed overestimation and a negative value showed underestimation. The mean error and mean absolute error values between the dental age and the chronological age were recorded.

Descriptive statistics were calculated that included the mean, standard deviation, mean error, and mean absolute error. The Wilcoxon signed-rank test was used to compare the dental age and the chronological age. P values less than 0.05 were considered to be statistically significant. All statistical analyses were performed using IBM SPSS for Windows, Version 27, Chicago, IL, USA.

Table 1. Distribution of the samples by age group and sex.

RESULTS

The results of the Demirjian method showed statistically significant differences between the chronological age and the dental age in both males and females (P < 0.0001), and the mean error values were 0.28 and 0.24 years for males and females, respectively. Moreover, the mean absolute errors were 0.68 years for males and 0.56 years for females (Tables 2 and 3).

The Willems method demonstrated better results in this study, which indicated no statistically significant difference between the chronological age and dental age in males (P = 0.619) with a mean error of −0.04 years. However, there was a statistically significant difference between the chronological age and dental age in females (P = 0.001) with a mean error of −0.23 years. In addition, the mean absolute errors were 0.55 years for males and 0.60 years for females (Tables 4 and 5).

Figures 1 and 2 showed the mean error between the chronological age and the dental age using the Demirjian and the Willems methods in males and females, respectively.

Table 2. Comparison between the Demirjian dental age (DA) and chronological age (CA) for males.

Note: *Statistically significant difference using Wilcoxon signed-rank test

Abbreviations: n = number of samples, SD = standard deviation, ME = mean error, MAE = mean absolute error

Table 3. Comparison between the Demirjian dental age (DA) and chronological age (CA) for females.

Note: *Statistically significant difference using Wilcoxon signed-rank test

Abbreviations: n = number of samples, SD = standard deviation, ME = mean error, MAE = mean absolute error

Table 4. Comparison between the Willems dental age (DA) and chronological age (CA) for males.

Note: *Statistically significant difference using Wilcoxon signed-rank test

Abbreviations: n = number of samples, SD = standard deviation, ME = mean error, MAE = mean absolute error

Table 5. Comparison between the Willems dental age (DA) and chronological age (CA) for females.

Note: *Statistically significant difference using Wilcoxon signed-rank test

Abbreviations: n = number of samples, SD = standard deviation, ME = mean error, MAE = mean absolute error

Figure 1. Mean error between the chronological age and the dental age using the Demirjian and the Willems methods in males.

Figure 2. Mean error between the chronological age and the dental age using the Demirjian and the Willems methods in females.

DISCUSSION

Age estimation is a crucial parameter in forensic sciences, clinical medicine, and clinical odontology. The value of estimating age is to determine individual status without legal documents and identify unknown dead persons (Khorate et al., 2014). Dental age estimation in children and adolescents can be divided into two methods: tooth eruption and tooth development (Tunc and Koyuturk, 2008). Tooth development is more accurate than the tooth eruption method because dental development is less influenced by environmental and nutritional factors (Moorrees et al., 1963; Infante and Owen, 1973). Therefore, the tooth development method was chosen to estimate the chronological age in this study.

The Demirjian method (Demirjian et al., 1973) and the Willems method (Willems et al., 2001) are based on dental development transformations that can be clearly identified in each stage and have been the most widely used methods for dental age estimation using the radiographic method in several populations (Lee et al., 2011; Nik-Hussein et al., 2011; Djukic et al., 2013; Ambarkova et al., 2014; Ye et al., 2014; Akkaya et al., 2015; Duangto et al., 2016; Zhai et al., 2016; Hegde et al., 2017; Kelmendi et al., 2018; Esan and Schepartz, 2018; Nemsi et al., 2018; Ozveren and Serindere, 2018; Wang et al., 2018; Yang et al., 2018; Gelbrich et al., 2020; Han et al., 2020; Pan et al., 2021; Brkić et al., 2022; Shi et al., 2022). However, limited studies are available for application in the population of southern Thailand. Therefore, this study focused on investigating the accuracy of dental age estimation in a group of children and adolescents in southern Thailand. 

Consistent overestimation of chronological age was found using the Demirjian method in the subjects of this study, which was also reported in several populations (Lee et al., 2011; Djukic et al., 2013; Ye et al., 2014; Akkaya et al., 2015; Brkić et al., 2022; Duangto et al., 2016; Hegde et al., 2017; Kelmendi et al., 2018; Yang et al., 2018; Han et al., 2020; Pan et al., 2021). In the population of this current study, the mean error values between the chronological age and the Demirjian dental age were 0.28 years for males and 0.24 years for females, which were similar to the results of the previous study conducted in northern Thailand (Duangto et al., 2016). However, the Willems method underestimated the ages of the males and females by −0.04 years and −0.23 years, respectively. The overall mean error in dental age estimation was lower using the Willems method. This finding was consistent with the results of previous studies (Lee et al., 2011; Nik-Hussein et al., 2011; Djukic et al., 2013; Ambarkova et al., 2014; Ye et al., 2014; Akkaya et al., 2015; Hegde et al., 2017; Esan and Schepartz, 2018; Kelmendi et al., 2018; Ozveren and Serindere, 2018). The mean error in dental age estimation in our study indicated that the Willems method was more accurate that the Demirjian method in the population of southern Thailand. However, both methods are applicable for estimating the ages of children in southern Thailand since the mean errors and mean absolute error values were less than one year.

CONCLUSION

The Willems method was more accurate for dental age estimation compared with the Demirjian method. However, both methods are valid for estimating the ages of children and adolescents in southern Thailand given that the mean error and mean absolute error values were less than one year.

ACKNOWLEDGMENTS

The authors greatly appreciate the Dental Hospital, Faculty of Dentistry, Prince of Songkla University, Songkhla, Thailand for facilitating support of this study.

AUTHOR CONTRIBUTIONS

Conceptualization: Pornpat Theerasopon and Phuwadon Duangto. Data acquisition: Chairat Charoemratrote. Data analysis or interpretation: Pornpat Theerasopon and Phuwadon Duangto. Drafting of the manuscript: Pornpat Theerasopon and Phuwadon Duangto. Critical revision of the manuscript: Pornpat Theerasopon and Phuwadon Duangto. Approval of the final version of the manuscript: all authors.

CONFLICT OF INTEREST

No potential conflict of interest relevant to this article was reported.

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