Age assessment is frequently required for medical odonatological purposes to predict the optimal time for treatment and especially for forensic purposes. Therefore, the estimated age should be as accurate as possible.7,20
DA estimation is commonly used worldwide and is thought to correlate with CA better than other maturity indicators of a child’s development.21 Several methods have been introduced to estimate DA depending on either calcification (tooth development)7,20,22,23 or eruption patterns.24 Relying on eruption dates when attempting to assess DA is complicated by the fact that tooth emergence may be significantly affected by local exogenous factors, such as infection, obstruction, crowding, and premature extraction of the deciduous predecessor or adjacent permanent teeth.25 These mishaps can be avoided by interpreting radiographic data representing the tooth development stages.
One of the most commonly used radiographic methods is the method reported by Demirjian et al., which established a standard based on a large sample that included 1446 males and 1482 females of French-Canadian origin.4 Although observer agreement is usually reported when using Demirjian’s method, there is an evident tendency towards overestimation of a subject’s age,7 which may be a result of ethnic differences between populations26 and a positive secular trend over the last 50 years.27 The debate regarding the applicability of Demirjian’s method to all races and populations.1,2,12,13,14,15,16 encouraged the authors to assess the applicability of Demirjian’s method and to develop new prediction equations, if needed.
In the current study, the inter- and intra-observer agreement was satisfactory, denoting the reliability of radiographic interpretation. In addition, statistical testing using linear regression was conducted to modify the maturity scores generated using Demirjian’s method. Logistic regression analysis may be a suitable method when it is needed to assign a subject with a specific age.10,27
Intraoral radiographs are usually predisposed to image distortion; therefore, archived DPTs were used because they were not only accessible but also enabled visualization of all of the teeth together, which was the recommended method reported by Demirjian et al.4,21
Although our sample size appears small compared to those of similar studies, a small sample size is not considered a limitation in forensic scientific research.28 Moreover, our sample size was larger or relatively equal to those of other studies. These studies included a cross-sectional study that compared EDAs with CAs in 162 Somali and white Caucasian children residing in Sheffield. The outcomes of that study highlighted the need for population-specific dental development standards for accurate assessment of DA.29 Likewise, Prabhakar et al. tested the applicability of Demirjian’s method among 151 Indian children living in Davangere. They found that the Davangere children were dentally more advanced and that Demirjian’s method was not applicable to their study group.30 Other studies with larger sample sizes than ours, including those that surveyed older age groups, recommended creation of an adaptive tool to avoid the overestimation observed using Demirjian’s method.1,3,10,31,32
Our results revealed an overestimation by 0.466 years in the male group, which was similar to the results obtained using similar age groups of Serbian (0.45 years),9 Dutch (0.4 years),33 and French (0.47 years) males.34 In addition, the currents results are in accordance with those of studies reported for Iranian (0.34 years)35 and southern Turkish (0.52 years) children,15 albeit to a lower intensity. In the female group, a mean difference of 0.325 years was calculated between the EDAs and CAs. Similar findings were reported among females living in Tanta, Egypt (0.294 years)32 and Norway (0.3 years).36 This coherency is most likely attributed to the fact that Egyptians, similar to many European populations, are all European-ancestry populations and share more or less the same geographical characteristics.37
The reverse observations were reported for South Indians (3.04 years in males and 2.82 years in females),26 Saudis living in Rayed (0.3 years for males and 0.4 years for females),31 Kuwaitis (0.71 years for males and 0.67 years for females),38 and Tunisians (from 0.3 to 1.32 year for males and from 0.26 to 1.37 year for females).10 The differences in age estimation between our study and those of other studies may be related to differences in the sample size, age groups, and studied populations. Other factors, such as socioeconomic status, nutrition, and dietary habits, may also affect the outcomes.10
The results of the current study revealed that dental maturation was more advanced in the examined males than in the studied females (mean differences between EDAs and CAs of 0.466 and 0.325 years for males and females, respectively). In addition to the absence of a significant difference between the male and female groups, the sexual dimorphism of the acceleration of dental maturation estimated by Demirjian’s method differed in numerous studies. Some researchers have reported acceleration of the EDA in females compared to that in males.10,32,39 However, the EDA among males could be in advance of that in females, as reported by Duangto et al.,40 who examined a Thai population and found mean differences of 0.11 and 0.10 years for males and females, respectively. In addition, Gungor et al.15 evaluated the applicability of Demirjian’s method for an elderly southern Turkish population and reported that the mean differences between the chronological and DAs ranged from 0.04 to 0.85 years and from 0.02 to 0.79 years in males and females, respectively. Moreover, a cross-sectional study among the Malay population clearly stated that Demirjian’s method overestimated the age by mean differences of 0.75 and 0.61 years among males and females, respectively.21
Although the current results and other reports have suggested that Demirjian’s method can be unsuitable as a forensic age estimation tool,7,23 Demirjian’s method is still a recommended method to assess individual dental maturity.41 Notably, no method has the ability to accurately determine the exact CA, because differences between the EDA and CA appear not only due to the accuracy of the applied method but also due to other factors, such as the examiners’ skills and experience, the studied sample size and distribution, developmental and environmental variability between the studied subjects themselves, and the methods used to analyze and interpret the obtained results.42
Our study showed the absence of a specific trend in addition to significant differences between some of the studied age groups. Thus, we found that Demirjian’s original standards did not accurately estimate the CA in our studied sample and that the EDA generally overestimated the CA upon application of Demirjian’s method in many populations. The authors strongly believe that each population requires its own adaptive dental maturity score. This concept of developing a specific prediction equation for each population is becoming more strongly supported.16
A limitation of the current study was that because our sample only represents Minia city, it may not represent the general Egyptian population. Therefore, the developed prediction equation requires modifications prior to application to the whole Egyptian population. Moreover, other limitations were the clinical nature of the sample, the age range of the children, three to 10 years, which includes very young individuals showing the earlier stages of permanent tooth development that are typically not part of such studies because of the ethical issues associated with radiography of children under five years; small cohort sizes; and the cross-sectional nature of the data, which is always a limitation when examining growth patterns.