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REVIEW ARTICLE
Year : 2022  |  Volume : 10  |  Issue : 1  |  Page : 1-7

Radiological and nonradiological methods of dental and skeletal age assessment: A narrative review


Department of Pediatric and Preventive Dentistry, Subharti Dental College and Hospital, SVSU, Meerut, Uttar Pradesh, India

Date of Submission25-Feb-2022
Date of Decision26-Feb-2022
Date of Acceptance26-Mar-2022
Date of Web Publication21-Apr-2022

Correspondence Address:
Ashima Tyagi
Department of Pediatric and Preventive Dentistry, Subharti Dental College and Hospital, Swami Vivekanand Subharti University, Meerut, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jomr.jomr_5_22

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  Abstract 


Age is one of the essential factors which play an important role in every aspect of life. Importance of age determination is related to many fields including treatment planning and drug delivery in pediatric dentistry, orthodontics, forensic sciences, and also in individuals who provide inaccurate details of age as in cases of illegal immigrants and in the corpse of unknown identity. The age estimation methods at different stages of life consist of a physical examination, radiographic examination of the hand bones and cervical vertebrae, and dental examination using two-dimensional and three-dimensional imaging. The different dental age estimation methods used are morphological, biochemical, and radiological methods. These methods have inborn advantages and disadvantages. Other than dental age, skeletal age has also been used to determine a child's development as skeletal maturity is closely related to the craniofacial growth. Correlation of the dental and skeletal ages with the chronological age of children helps clinicians to estimate the growth left in the child and the possible treatment that can be carried out utilizing it. This article critically reviews various dental and skeletal aspects of age estimation from infancy to adulthood with its scope and limitation.

Keywords: Age estimation, cervical vertebrae, Demirjian method, dental age, hand–wrist radiograph, skeletal age


How to cite this article:
Tyagi A, Srivastava N, Rana V, Kaushik N. Radiological and nonradiological methods of dental and skeletal age assessment: A narrative review. J Oral Maxillofac Radiol 2022;10:1-7

How to cite this URL:
Tyagi A, Srivastava N, Rana V, Kaushik N. Radiological and nonradiological methods of dental and skeletal age assessment: A narrative review. J Oral Maxillofac Radiol [serial online] 2022 [cited 2022 May 21];10:1-7. Available from: https://www.joomr.org/text.asp?2022/10/1/1/343693




  Introduction Top


The time that an organism or individual survives after birth is referred to as the chronological age which plays an important role in every aspect of life. Thus, chronological age is recorded by registration of the birth date of an individual and is referred throughout an individual's life.[1] The status of child's development is usually assessed in relation to events that take place during progress of growth. The age estimation at different stages of life is done in various fields including anthropological studies for the identification of a mutilated body of a victim and in medicolegal issues, etc.[2] In the field of pediatric dentistry, the assessment of age is also useful in the treatment planning of orthodontic treatment in the case of myofunctional appliances and acts as a source of complementary information for pediatricians. Although height and weight measurements are one of the powerful tools in growth assessment but these are clinically impractical as these are dynamic in nature and require values.[3] With technical advancements, in digital radiography and cone-beam computed tomography, the status of calcification can be determined precisely.[4] Therefore, this review article is aimed at describing various dental and skeletal methods utilized for human age assessment.


  Age Estimation Methods Top


Age estimation is of immense importance in dentistry for treatment planning, drug dose delivery, and patients requiring interceptive orthodontic therapy. Chronologic age conveys only an irregular approximation of the maturational status of a person, hence dental and skeletal ages have been explored as maturity indicators for decades. The estimated age of an individual, obtained from the stages of dental development, is defined as the dental age while skeletal age is defined as an interpretation of skeletal maturity based on radiographs of the left hand and wrist or cervical vertebrae that have provided useful information in various clinical practices.[3]

Age estimation methods in individuals can be mainly contributed by three components:

  1. Assessment of dental development
  2. Assessment of skeletal maturity
  3. Expression of secondary sexual characteristics.


Assessment of dental development

Age estimation using teeth can be assessed by examining tooth eruption and maturation.[5] The dental age has a significant role in forensic investigations and in clinical applications to determine the degree of maturation in children and adolescents.[6] Several methods of dental age estimation have been proposed. These may be described in two categories, namely:[2]

  • Nonradiographic methods
  • Radiographic methods.


Nonradiographic methods can further be divided into these methods:

  • Visual observation
  • Physical and chemical analysis
  • Histological methods.


Visual methods include observation of stages of eruption of teeth and evidence of changes due to function such as attrition, which give an approximate estimation of age, presence or absence of mamelons, and presence of teeth/absence of teeth.[7] A study was conducted by Gorea et al.[8] to correlate the prevalence of the mamelons with age, sex, and occlusal relationship found that more mamelons present in the first decade of life which decrease with increasing age and are more prominent in permanent maxillary central incisor and persist more in females than males.

Physical and chemical methods are based on the racemization of amino acids. The racemization of amino acids is a reversible first-order reaction and is relatively rapid in living tissues in which metabolism is slow. The methods which are used for physical and chemical analysis include Helfman and Bada method and Ritz method which evaluated the age of living individuals without extracting teeth.[6]

Histological methods require the preparation of tissues for detailed microscopic examination which can determine more accurately the stage of development of dentition. Gustafson (1950), Dalitz (1962), Bang and Ramm (1970), Johanson (1971), Maples (1978), and Solheim (1993) are few histological methods used for age assessment.[9]

Radiology plays an indispensable role in the human age determination and is one of the essential tools in identification in forensic science.[10] The methods based on the stages of tooth formation on periapical and orthopantomography seem to be appropriate in the assessment of age as the dental development and calcification is controlled more by genes than by environmental factors. There is high evidence that three-dimensional radiographs are more reproducible and reliable in dental age estimation. Quantitative metric and volumetric analysis demonstrated better performance in predicting chronological age than staging.[11] The age determination on radiographs is based on the estimation of various features such as tooth germ appearance, beginning of mineralization both in the intrauterine life and after birth, amount of crown completion, eruption into the oral cavity, degree of root completion of erupted or unerupted teeth, degree of resorption of primary teeth, measurement of open apices, volume of pulp chamber and root canals/formation of physiological secondary dentin.

The radiographic methods of age estimation are grouped into three phases:[2]

  1. Age estimation in prenatal, neonatal, and postnatal ages (Kraus and Jordan)
  2. Age estimation in children and adolescents
  3. Age estimation in adults.


Age estimation in prenatal, neonatal, and postnatal ages

Primary teeth start to develop in the 6th–8th gestational week and permanent teeth in about the 20th week of gestation period. Age estimation using dental development during fetal and neonatal periods must be based on the degree of calcification of primary dentition which is observed by radiographic means. Kraus and Jordan proposed a method for age estimation in prenatal, neonatal, and postnatal ages which is denoted in Roman numerals as I to X: the IXth stage including three substages and the Xth stage including five substages[12] [Figure 1].
Figure 1: Stages of dental development by Kraus and Jordan

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Age estimation in children and adolescents

Age estimation in children and adolescents used the stage of mineralization of teeth observed in radiographs. And then coding is done as per the regression chart. The oldest method for children and adolescents was proposed by Schour and Massler. In this method, the authors studied the development of primary and permanent teeth, describing 21 chronological steps from 4 months to 21 years of age, and published a numerical development chart for them. The authors compared the calcification stages of teeth on radiographs with the standards; however, the gender difference was not considered [Figure 2].[13] In 2018, George et al.[14] conducted a study to check the efficacy of Schour and Massler method to determine the dental age in the individuals within the age group of 5–16 years and concluded that the dental age estimation by Schour and Massler method is simple and less time-consuming than other tooth-specific methods.
Figure 2: The Schour and Massler's pictorial representation of teeth

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Another method was described by Glesier and Hunt which included detailed calcification of mandibular first molars based on radiographs. A serial or longitudinal study of the calcification and eruption of the right permanent mandibular first molars was studied for children and further the radiographic images of this tooth were divided into 15 stages of calcification[15] [Figure 3].
Figure 3: Dental developmental chart by Gleiser and Hunt

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In 1963, Carmen Nolla introduced a method which evaluated the mineralization of permanent dentition in 10 stages through each of which every tooth passed [Figure 4]. The method is used to assess the development of each tooth of the maxillary and mandibular arch. The radiograph of the patient is matched with the comparative figure. Each stage also had a numerical score. The scores were totaled to give a combined “sum of stages” score that was then divided by the number of teeth taken into consideration to give the dental age [Table 1].[16] In most of the studies, it was found that Nolla's method of age estimation had better accuracy and no significant differences in the rates of development were observed in males and females.[17]
Figure 4: Nolla's dental developmental chart

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Table 1: Age norms for maxillary and mandibular teeth of boys and girls

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Demirjian, Goldstein, and Tanner rated seven mandibular permanent teeth in the order of second molar (M2), first molar (M1), second premolar (PM2), first premolar (PM1), canine (C), lateral incisors (I2), and central incisor (I1) and determined eight stages (A to H) of tooth mineralization [Figure 5]. If there is no sign of calcification, the rating 0 is given; the crypt formation is not taken into consideration. The stages are the indicators of dental maturity of each tooth. In this method, missing teeth from one side can be replaced by those from the other side. Comparatively, Demirjian's method is one of the simplest, most practical, and widely employed methods to predict age and maturation, as it comprises clearly defined changes in shape that do not require speculative estimation. However, it has some disadvantages that the evaluation cannot be applied in children with missing teeth and this method may not express the retardation of dental development (excluding third molars) due to systemic diseases.
Figure 5: Demirjian's chart

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To overcome these drawbacks, the calculation of several “modified” versions of the original Demirjian tables for different populations was offered.[18]

In 2006, Cameriere et al. presented a method for assessing chronological age in children based on the relationship between age and measurement of open apices in teeth. Seven lower teeth (excluding the third molars) from the left side are used. The height of the calcifying teeth and width of their “open” apex is measured and the ratio is calculated. Such a ratio is derived to compensate for magnification and angulation errors that may have been induced during radiography.

  • Age = 8.971 ± 0.375 g ± 1.631 × 5 ± 0.674 N0 − 1.034 s − 0.176 s N0.


Where g is a variable equal to 1 for boys and 0 for girls.[19]

Haavikko method is also based on the degree of tooth calcification and presents a total of 12 radiographic calcification stages for the crown and root development for determining dental age. Although this method is useful when a permanent tooth is missing, an underestimation of dental age was observed using this method.[20]

Age estimation in adults

Age estimation in adults is challenging, as with the eruption of third molars (17–21), permanent dentition is said to have completely developed and it becomes difficult to estimate age based on radiographs. Thus, the two criteria that can be utilized for age determination in adults are assessment of volume of pulp cavity and third molar development.

Volume assessment of the teeth involves pulp-to-tooth area ratio method and coronal pulp cavity index. The reduction in the size of the pulp cavity resulting from a deposition of secondary dentin with aging as assessed by radiography can be taken as a guide to estimate the age of the individual. Some of the limitations of this method were that only those individuals who retained all six teeth were included in this method. Furthermore, a certain amount of distortion is also seen when the curved arch of the jaws is projected onto a flat film. Finally, rotated teeth, teeth with enamel overlap, teeth with restorations, cavities, attrition, and periapical pathological process cannot be used in this method.[21]

The coronal pulp cavity index is a reliable biomarker for age assessment in the forensic context, especially in living individuals of unknown personal data. Only mandibular premolars and molars were considered on panoramic radiographs. The tooth-coronal index (TCI) is calculated for each tooth and regressed on the real age of the sample using the formula.[21]

  • TCI = Certificate Programme in Community Health (CPCH) × 100/crown length (CL). TCI = CPCH × 100/CL
  • Where CPCH = the length of the coronal pulp cavity and
  • CL = the length of the tooth crown.


The accuracy of dental age estimation in adults using evaluation of development of the third molar is questionable owing to great variability in its development. Harris and Nortje gave five stages of the third molar root development with corresponding mean ages and mean length. Van Heerden assessed the development of the mesial root of the third molar to determine the age. He described the development of the mesial root in five stages using panoramic radiographs. The males and females were surveyed separately, and no significant differences were found between them.[22],[23]

Assessment of skeletal maturity

The assessment of skeletal maturity is a clinical procedure and is often referred to as bone age (or bone aging). It is usually based on the imaging of two body parts:

  • The left hand–wrist
  • Using cervical vertebrae.


In hand–wrist radiographs, numerous small bones of the hand and wrist are taken into consideration. These bones show a predictable and scheduled pattern of appearance, ossification, and union from birth to maturity. Thus, by merely comparing a patient's hand–wrist radiograph with standard radiograph that represents different skeletal ages, the skeletal maturation status of an individual can be determined. Twenty ossification centers are generally used for determining skeletal age which include[24] [Figure 6].
Figure 6: Hand–wrist radiograph for skeletal age assessment

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  1. Carpal bones, metacarpals, and patella in both sexes
  2. Distal and middle phalanges in boys
  3. Distal and proximal phalanges in girls.


The most frequently used method to evaluate skeletal age from hand–wrist radiographs is the  Atlas More Details of Greulich and Pyle. This method is widely accepted for evaluating skeletal development with hand–wrist radiography, including the bones of different structures. One of the limitations of this method is that lack of sufficient standard images at the time of puberty reduces the accuracy of the age estimation and increases interobserver error.[25]

In 1995, Hassel and Farman developed cervical vertebrae [Figure 7] as maturity indicators by assessing the lateral profile changes of the second, third, and fourth vertebrae. The authors have put forward the following six stages in vertebral development [Figure 8]. The cervical vertebral maturity indicators were evaluated against skeletal maturation index established from hand–wrist radiograph by Fishman.[26]
Figure 7: Assessment of skeletal maturation using cervical vertebrae

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Figure 8: Stages of Vertebral development by Hassel and Farmann

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Many research studies were conducted to comparative evaluate the hand–wrist and cervical vertebrae to know the validity of cervical vertebrae as maturity indicators. The authors further concluded that skeletal maturity indicators provide a more valid basis than chronological age for the growth status of individuals and there is no significant difference between the two techniques of evaluation. Hence, they stated that cervical vertebrae can be used in a similar manner that hand-wrist radiograph are used to evaluate skeletal maturity, thus avoiding the need for an additional radiograph.[27],[28]

Expression of secondary sexual characteristics

The process of maturation at puberty is a multidimensional set of events that can be, and has been, utilized for age-related evaluation. Female maturation within this process is generally assessed based on the age of onset of menses, degree of breast development, and degree of axillary and pubic hair. Male maturation is generally assessed on the basis of testicular and penile enlargement and also on the degree of hair development, mainly pubic but also axillary and facial.[5]


  Conclusion Top


Determination of age from infancy to adulthood is done by reference to the ever-growing human deciduous and permanent dentitions and by assessment of skeletal maturity. Demirjian method, the widely used method with appropriate modifications, is considered a reliable method. Besides dental age, skeletal development evaluation using hand–wrist radiographs and cervical vertebral maturation have been frequently used has received growing interest as a biological indicator of skeletal development. However, hand–wrist radiographs have been found as more useful method of studying skeletal age. Several researchers have evaluated the association between dental and skeletal maturities with chronologic age on different populations. Thus, based on an appropriate knowledge of the available methods, it is recommended that rather than restricting on one age estimation technique, using other techniques and performing repetitive measurements is beneficial for accurate age estimation.

Acknowledgment

I would like to acknowledge my institution, Subharti Dental College and Hospital, Head of Department, and my co-guides for their constant support throughout this research.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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