The relationship between dental age, bone age and chronological age in underweight children

Abstract

Background and Objective:

The knowledge of bone age and dental age is of great importance for pediatrician and pediatric dentist. It is essential for a pediatric dentist to formulate treatment plan and it is a source of complementary information for pediatrician. There are few studies, which showed the relationship between dental age, bone age and chronological age in underweight children. Therefore, objective of this study was to determine and compare dental age, bone age and chronological age in underweight children.

Materials and Methods:

100 underweight children between the age group of 18-14 years were selected. Chronological age was assessed by recording date of birth. Dental age assessment was done using orthopantamogram following the method described by Demirjian. Bone age assessment was carried out using hand wrist radiograph following Bjork, Grave and Brown′s method.

Results:

Dental age and Bone age was delayed compared to chronological age in both sexes. The correlation between chronological age, dental age and bone age were all positive in males.

Interpretation and Conclusion:

The data supports the concept that dental age and bone age delay is a significant feature in underweight children. It is important to consider dental age and bone age as variables for diagnosing underweight children. To support our findings further a well-designed, controlled as well as longitudinal studies with a larger sample size is required.

Growth is an essential feature of life of a child that distinguishes him or her from an adult. The process of growth starts from the time of conception and continues until the child grows into a fully mature adult. Growth denotes a net increase in the size or mass of tissues, whereas development specifies maturation of functions.[1]

Hereditary, functional, environmental, nutritional, sexual, metabolic, social, emotional, cultural factors affect growth and development greatly.[2]

Bone age is an indicator of physiological development and is distinct from the chronological age.[1]

The appearance and union of the different skeletal centers of ossification follows a fairly definite pattern and time schedule from birth to maturity. A Roentgenographic study of these skeletal maturational processes provides a valuable criterion of the child′s level of osseous maturation. The skeletal maturity of the individual is known as bone age.[2]

The development and eruption of the teeth are part of the child′s total development. Tooth development is a useful measure of maturity, since it represents a series of recognizable events that occur in the same sequence from an initial event to a constant end point. Estimation of dental age is based upon the rate of development and calcification of tooth buds and their progressive sequence of eruption in the oral cavity. The tooth calcification provides a valuable indicator of dental age and serves as an index of the maturation of the child. Dental formation of calcification, which is a continuous development process, should be considered a better measure of physiological maturity than dental emergence. Several methods have been developed in order to assess the dental age according to the degree of calcification observed on permanent teeth. One such widely used method is that given by Demirjian, Goldstein and Tanner based on a large number of Canadian children.[3]

The early prevention and interception of dento-facial deformities is dependent upon an accurate interpretation of the inherent facio-skeletal pattern and the overall growth and development. Physical growth and developmental manifestations provide useful criteria for orthodontic diagnostic evaluations. Physical characteristics such as weight, height, skeletal maturation and dental development, which are subject to biometric tests and compared with standards based upon large groups of healthy subjects in order to evaluate the growth and maturational status of patients.

Height and weight are the physical manifestations of growth and development that is probably utilized most in diagnostic procedures and in assessment of growth and development. Body weight is probably the best index of nutrition and growth because it sums up all increments in size.[2]

Weight for height below the 5^th % is the best indicator of acute under nutrition and underweight. Body mass index (BMI) is widely accepted as the best clinical measure of underweight. BMI can be calculated as weight/height squared. According to Centers for disease control (CDC), a BMI over the 95^th % indicates “overweight,” between 85^th and 95^th is “risk for overweight,” and below the 5^th % are “underweight.”[4]

To widen the scope of thinking about the impingement of growth and development on dental problems and perhaps to improve one′s clinical judgment, a comprehensive study of the dental development should be very useful.[5]

Bone age and dental age is useful to the dental practitioner in planning treatment. It′s useful for the pediatrician and endocrinologist as a source of complimentary information.[6]

The relationship between dental, skeletal and chronological age will be estimated in order to correlate the 3 ages for diagnostic purpose. The differences between dental, skeletal and chronological age is of great interest in indicating an advancement or delay compared to standard growth.[3]

There are few studies, which showed the effect of bone and dental maturity in children with underweight.

Accordingly, the aim of this study is to determine and compare dental age, bone age and chronological age in children with underweight.

Materials and Methods

The present study was conducted in the Department of Pedodontics and Preventive Dentistry Ame′s Dental College, Raichur. The children were selected from the Outpatient department of Pedodontics and Preventive Dentistry, Ame′s Dental College, Raichur. Ethical clearance was obtained from the ethical clearance committee of the College.

The nature of study was explained and informed consent was obtained from the parent of the patient. Sample sizes of 100 underweight children were selected between the age group of 8-14 years. Weighing child and measuring child′s height than BMI is calculated by using a formula weight/height² (weight should in kilograms and height in meters), if the BMI is under 5^th % for his/her age and gender, than he/she is technically considered underweight [Tables 1 and 2].

Table 1.

Body mass index percentiles for age in boys, 2-20 yr[4]

Table 2.

Body mass index percentiles for age in girls, 2-20 yr[4]

Armamentarium included

1. Weighing scale (To measure weight)

2. Growth percentile chart (CDC 2000 Standards)

3. Stadiometer (To measure height)

4. Orthopantomograms (OPG)

5. Hand-Wrist radiographs

6. X-ray viewer

The chronological age was determined from the actual date of birth either stated by parents or guardians or as per school records. An OPG and hand wrist radiograph was taken for each of the child to determine dental age. Interpretation of the radiographs was carried out with the help of an X-ray viewer.

Method of dental age estimation

Determination of dental age was based upon the rate of development and calcification of tooth buds. Dental age estimation was done using Demirjian′s method considering 7 permanent left mandibular teeth from central incisor to II molar (If any tooth was congenitally missing, contra lateral tooth was considered).

Demirjian, et al.,[7,8] divided tooth development into 8 developmental stages from A to H [Figure 1]. Each tooth was assigned a score based on its developmental Stage [Table 3 and Table 4]. The sum of 7 individual scores gives maturity score, which is converted into dental age using conversion chart [Tables 5 and 6].

Figure 1.

Demirjians tooth mineralization stages

Table 3.

Self-Weighted scores of dental stages of 7 teeth (Mandibular left side) in boys[3]

Table 4.

Self-weighted scores of dental stages of 7 teeth (Mandibular left side) in girls[3]

Table 5.

Conversion of maturity score to dental age: For boys[3]

Table 6.

Conversion of maturity score to dental age: For girls[3]

Method of dental age estimation

→ OPG′s [Figure 2] were analyzed for the developmental stages of all the 7 left permanent mandibular teeth as per Demirjian′s method [Figure 1].

Figure 2.

Orthopentamograph

The developmental stage of each tooth was assessed and then each tooth was given a score according to its stage of development using the score table [Tables 3 and 4]. Adding 7 individual scores from permanent central incisor to 2^nd permanent molar gives a maturity score, maturity score will be converted into dental age using conversion chart [Tables 5 and 6].

Demirjians tooth mineralization stages [Figure 1] are as follows:

Stage A: Beginning mineralization of separate cusps.

Stage B: Fusion of cusps.

Stage C: Beginning of dentinal deposits is seen.

Stage D: Crown formation completed down to the cemento-enamel junction.

Stage E: The root length is less than the crown height.

Stage F: The root length is equal to or greater than crown height.

Stage G: The walls of the root canal are parallel and its apical end is still partially open.

Stage H: The apical foramen is completed.

Bone age assessment

The bone age was assessed by means of hand-wrist radiograph using Bjork, Grave and Brown′s method.[9] They have divided the maturation process of hand-wrist bones into 9 developmental stages. Each of these stages represents a level of skeletal maturity. Appropriate age for each of the stage was given by Schopf in 1978.

Method of bone age assessment

Hand-wrist radiographs [Figure 3] were viewed on the X-ray viewer and its developmental stage was assessed in accordance with Bjork, Grave and Brown′s Method.

Figure 3.

Hand wrist radiograph

The appropriate age given for that developmental stage was recorded and the obtained age was known as bone age. The obtained data was subjected to the statistical analysis.

Results

The study comprised a total of 100 underweight children, 64 males and 32 females in the age group of 8-14 years. Dental age estimation was done using Demirjian′s method and Bone age assessment was done using Bjork, Grave and Brown′s method. The chronological age, bone age and dental age were compared using the unpaired Student′s t-test and Pearson′s correlation coefficient.

Following are the results obtained in both sexes:

In females

By comparing chronological age, dental age and bone age, the following was observed:

1. The mean difference between chronological age and dental age was 1.86 years, i.e., Dental age was reduced compared to chronological age by 1.86 years [Table 7 and Table 8].

2. The mean difference between chronological age and bone age was 1.61 years, i.e., bone age was retarded compare to chronological age by 1.61 years [Table 7 and Table 8].

3. The mean difference between dental age and bone age was −0.25 years, i.e., dental age was reduced compared to bone age by 0.25 years [Table 7 and Table 8].

Table 7.

Mean chronological age, dental age and bone age of females and males

Table 8.

Comparison of chronological age, dental age and bone age in females

By obtaining correlation between chronological age, dental age and bone age the following was observed:

1. The chronological and dental age showed no significant correlation (r = 0.034) [Table 9].

2. The chronological and bone age showed no significant correlation (r = 0.158) [Table 9].

3. The dental age and bone age showed very highly significant positive correlation (r = 0.531) [Table 9].

Table 9.

Correlation between chronological age, dental age and bone age in females

In males

By comparing the values of the chronological, dental age and bone age, the following was observed:

1. The mean difference between chronological age and dental age was 2.06 years, i.e., Dental age was reduced compared to chronological age by 2.06 years [Table 3, Table 7 and Table 10].

2. The mean difference between chronological age and bone age was 1.05 years, i.e., chronological age was advanced compared to bone age by 1.05 years [Table 7 and Table 10].

3. The mean difference between dental age and bone age was-1.01 years, i.e., bone age was advanced compared to dental age by 1.01 years [Table 7 and Table 10].

Table 10.

Comparison of chronological, dental age and bone age in males

By obtaining correlation between chronological age, dental age and bone age the following was observed:

1. The chronological and dental age was found to be positively correlated and statistically very highly significant (r = 0.79) [Table 11].

2. The chronological and bone age was found to be positively correlated and statistically highly significant (r = 0.46) [Table 11].

3. The dental age and bone age was found to be positively correlated and statistically highly significant (r = 0.40) [Table 11].

Table 11.

Correlation between chronological age, dental age and bone age in males

Discussion

Knowledge of dental age and bone age is of great value from both medical and dental point of view. It′s useful for the pediatrician and endocrinologist as a source of complimentary information. Therefore this study was undertaken to determine and compare dental age and bone age in underweight children. The radiological study of hand-wrist is the single most useful method of studying bone age as stated by Greulich and Pyle.[10] In the present study bone age estimation was done using Bjork Grave and Brown method. Karina Emy Iguma:[11] Conducted a study to evaluate whether Martins and Sakima and Grave and Brown methods are useful for the bone age estimation using hand wrist radiograph. They found that 2 methods appeared to be highly and significantly correlated regarding bone age estimation using hand-wrist radiograph. Besides bone age, dental age has often been used to study the somatic maturity. Eruption and calcification of dental tissues has been used to determine dental age. Tooth calcification is superior to tooth emergence because emergence of a tooth a fleeting event and its precise time is difficult to determine, whereas calcification is a continuous process that can be assessed by permanent records such as X-ray films.[5] Nolla, Haavikko, Mooree′s and Demirjian′s methods are often used to determine dental age.

In the current study, dental age estimation was done using Demirjian′s method. Hagg and Matsson[12] compared the reliability of three different methods for the assessment of dental maturity and concluded that the method described by Demirjian and Goldstein affords a high degree of reliability and precision. Nanda and Chawla,[13] Hegde and Sood[5] studied the applicability of Demirjian′s method on Indian population. Their studies revealed the accuracy of Demirjian′s method when applied to Indian population.

In our study dental age and bone age delayed compared to chronologic age in both males and females. The results of our study are in agreement with those of Vallejo-Bolanos et al.,[6] Takano et al.,[14] Keller et al.,[15] and Sarnat et al.,[16] Vollejo-Bollenos et al.,[7] discovered a delay in dental age and bone age in 54 familial short statured children. Sarnat et al.,[16] Conducted a study on 19 patients with growth hormone deficiency and 13 patients with Laron type dwarfism discovered a delay in dental age of 1.8 and 1.7 years respectively for these 2 disorders. There is also a marked delay in dental age and bone age compared to chronological age between 2 sexes. These finding are in agreement with that of Vallejo-Bolanos et al.[17]

In our findings the co-relationships between dental age, bone age and chronological age were positive in males. We found similar results in other studies such as Vallejo-Bolanos et al.,[6] Green,[2] Hegde and Sood,[5] Prabhakar et al.,[3] who also discovered positive correlations between dental age, bone age and chronological age. Many researchers have focused on correlation ship between various maturity indicators and they are in agreement that there is positive correlation ship exists between various maturity indicators of growth.

Conclusions

We conclude that bone age and dental age delay is a significant feature in our sample of 100 underweight children. Our study showed the affect of underweight on dental and bone maturation.

Determination of bone age and dental age as opposed to chronological age is important to know the overall maturation of various tissue systems and its useful in dentistry to formulate treatment plan and its additional source of information in the field of Orthopedics, Forensics, Hematology, Pediatrics and Anthropology.