A comparative evaluation of dental calcification stages and skeletal maturity indicators in North-Indian children.

BACKGROUND: Many researchers have reported relationships between the calcification stages of individual teeth and skeletal maturity. A few studies are available in the literature about Indian populations. In view of this fact, this study was conducted to investigate the relationship between the dental calcification stages and skeletal maturity stages among North-Indian individuals. The objective of this study was to determine whether dental calcification can be used as a first-level diagnostic tool for assessment of skeletal maturity.
MATERIALS AND METHODS: The study participants included (60 males, 60 females) ranging from 7 to 13 years. A total of 120 dental panoramic radiographs and hand-wrist radiographs were obtained and analyzed. Calcification stages of the mandibular dentition (canines, first premolars, second premolars, and second molars) were rated according to the system of Demirjian et al. Skeletal maturity indicators stages were determined using the Fishman method. RESULTS AND
CONCLUSION: Bivarate correlation ranged from 0.58 to 0.75 for males and 0.73 to 0.84 for females. Canine showed the highest correlation in males and second molar showed the highest correlation in females. Canine calcification Stage H represent prepeak of the pubertal growth spurt in male patients. Calcification Stage G for second molar represents the prepeak and Stage H represents the peak of pubertal growth spurt in females.

INTRODUCTION

The maturational status of an orthodontic patient has a considerable influence on diagnosis, treatment goals, treatment planning, and the eventual outcome of the orthodontic treatment. Assessing maturational status and identification of the period of accelerated growth are essential for clinical decisions regarding growth modulation procedures for skeletal discrepancies, extraction versus nonextraction options, use of extraoral orthopedic forces, and planning for orthognathic surgery for skeletal malocclusions.

The chronologic age may have little or no place in the assessment of the maturational status of a child since it is governed by various factors such as genetic, epigenetic, environmental, nutritional, and hormonal. A more accurate measure to evaluate maturational status is, therefore “biologic age” based on somatic, sexual, dental, and skeletal maturational assessment.[1] The biologic age most closely related to growth has been the “skeletal age” and the hand-wrist film, the most standardized and studied method of skeletal assessment. Assessment of skeletal maturation using hand-wrist radiographs, as an index, based on time and sequence of appearance of carpal bones and certain ossification events have been reported by many investigators.[23] Ossification at the mid-palatal suture,[4] development of the frontal sinus[5] has also been used as indicators of skeletal maturation. Fishman[6] method has been among the most commonly used methods to assess skeletal maturation.

Dental development has been widely investigated as a potential predictor of the skeletal maturity level. In general, the dental development can be assessed using either the phase of tooth eruption or the stage of tooth calcification. Calcification stages of teeth instead of eruption are preferred because tooth formation is proposed as more reliable criteria for determining dental maturation.[7] Demirjian et al.[8] in 1973 described a method for estimating the dental age by reference to the radiologic appearance of seven teeth on the left quadrant of the mandible.

This study aims to determine an association, if any, between skeletal maturity and dental calcification stages. The stages of dental calcification might be used as a first-level diagnostic tool to estimate the timing of the pubertal growth spurt. The ease of recognizing dental developmental stages, together with the availability of intraoral or panoramic radiographs in most orthodontic or pediatric dental practices, are practical reasons for attempting to assess physiologic maturity without resorting to hand-wrist radiographs.[8]

The average age at which the onset of puberty occurs has dropped significantly since the 1840s. This was dubbed “the secular trend” by Tanner. Several studies report that there is a consistent lowering of the age at menarche on an average, by about 6 months per decade. Assessment of biologic age also throws light on the decreasing age in maturity in both boys and girls. Thus, maturation status cannot be assessed solely by determining the chronological age. It has been recognized that an individual's chronological age does not always correlate with the maturational age; skeletally, it may be retarded or advanced.[9]

Thus, for proper orthodontic diagnosis and treatment planning, accurate assessment of skeletal maturity is important. As a result, many investigators have attempted to predict the duration, magnitude, direction, and timing of the adolescent growth changes. The purpose of this study is to investigate the correlation between the stages of calcification of various teeth and skeletal maturation through hand-wrist radiographs.

Aims and objective

To investigate the correlation between calcification of teeth and scheduled pattern of appearance and ossification of bones of the hand wrist

To assess the reliability of dental calcification in evaluating the facial growth in an orthodontic patient.

MATERIALS AND METHODS

A total of 120 patients (60 males and 60 females) aged between 7 and 12 years were enrolled into the study. A total of 120 panoramic and hand-wrist radiographs were obtained and evaluated. The participants were chosen from patients visiting the Department of Orthodontics and Dentofacial Orthopedics, Department of Pedodontics and Department of Oral Medicine Diagnosis and Radiology, Saraswati Dental College and Hospital, Lucknow. A consent form was signed by each subject. Approval was obtained from the Human Research Ethics Committee, Saraswati Dental College, Lucknow.

The patients selected were physically and mentally healthy without a history of congenital or developmental disturbances due to syndromes or hormonal disturbance which could affect their growth. There was no previous history of trauma or injury to the face and the hand and wrist region.

Assessment of dental maturity was carried out through the calcification stages according to the method by Demirjian et al. from panoramic radiographs. These stages are as follows:

In both uni- and multi-radicular teeth, a beginning of calcification is seen at the superior level of the crypt in the form of an inverted cone or cones. There is no fusion of these calcified points

Fusion of the calcified points forms one or several cusps which unite to give a regularly outlined occlusal surface

Enamel formation is complete at the occlusal surface. Its extension and convergence toward the cervical region is seen. The beginning of dentinal deposit is seen. The outline of the pulp chamber has a curved shape at the occlusal border

The crown formation is completed down to the cementoenamel junction

The superior border of the pulp chamber in the uniradicular teeth has a definite curved form, being concave toward the cervical region. The projection of the pulp horns, if present, gives an outline shaped like an umbrella top. In molars, the pulp chamber has a trapezoidal form

Beginning of root formation is seen in the form of a spicule.

Uniradicular teeth

The walls of the pulp chamber now form straight lines whose continuity is broken by the presence of the pulp horn, which is larger than in the previous stage

The root length is less than crown height.

Molars:

Initial formation of the radicular bifurcation is seen in the form of either a calcified point or a semi-lunar shape

The root length is still less than the crown height.

Uniradicular teeth

The walls of the pulp chamber now form a more or less isosceles triangle. The apex ends in a funnel shape

The root length is equal to or greater than the crown height.

Molars:

The calcified region of the bifurcation has developed further down from its semi-lunar stage to give the roots a more definite and distinct outline with funnel-shaped endings

The root length is equal to or greater than the crown height.

Uniradicular teeth, molar

The walls of the root canal are now parallel and its apical end is still partially open (distal root in molars).

Uniradicular teeth, molar

The apical end of the root canal is completely closed (distal root in molars)

The periodontal membrane has a uniform width around the root and the apex.

Assessment of skeletal maturity was carried out with 11 grade system of Fishman (1982) [Figure 1]. The reason for considering this index was that it is the most commonly used skeletal l indicator and these 11 discrete adolescent skeletal maturational indicators (SMI) covering the entire period of adolescent development are found on six anatomical sites.

Figure 1

Skeletal maturational indicator Stages 1 to 11 (Fishman)

RESULTS

In males, the correlation between SMI and grades of calcification was found to be strongest for canine (ρ =0.755) and in females, second molar showed the strongest correlation (ρ =0.845).

In males, for canine, SMI I showed more correlation with Stage D and E. SMI II and III showed more correlation with Stage G. SMI IV and V correlated with Stage H.

For the first premolar, SMI I showed more correlation with Stage D. SMI II showed more correlation with Stage F. SMI III corelated with Stage H and SMI IV and V correlates with Stage G.

For second premolar, SMI I showed more correlation with Stage C as well as Stage H. SMI II showed more correlation with Stage E. SMI III, IV, and V showed more correlation with Stage G.

For second molar, SMI I showed more correlation with Stage C. SMI II showed more correlation with Stage E. SMI III showed more correlation with Stage G. SMI IV and V correlated with Stage H [Table 1].

Table 1

Correlation between skeletal maturity indicator and grades of calcification at different locations (males)

On the assessment of this relationship by calculating Spearman's rank correlation, the ρ value was 0.755 for canine which indicated the existence of a strong correlation between SMI and calcification grade for the canine. 0.659 for the first premolar, 0.582 for second premolar and 0.628 for second molar which indicated the existence of a moderate correlation between SMI stage and calcification grade for first premolar, second premolar, and second molar. Canine showed maximum correlation [Table 1].

Thus, in males, canine calcification Stage D and E correlated with SMI I. Dental calcification Stage G correlated with SMI II and SMI III. Dental calcification Stage H correlated with SMI IV and SMI V, which infers dental calcification Stage H represents prepeak of pubertal growth spurt.

In females, for canine, SMI I showed more correlation with Stage E. SMI II showed more correlation with Stage F. SMI III showed more correlation with Stage G. Stage IV, VI, VII, and VIII correlated with Stage H.

For first premolar, SMI I showed more correlation with Stage D. SMI II, III, and IV showed more correlation with Stage F. Stage III and IV correlated with Stage F. SMI VII showed correlation with Stage G. SMI VI and VIII correlated with Stage H.

For second premolar, SMI I, II, and III showed a better correlation with Stage D, E, and F, respectively. SMI IV, VI, and VII correlated with Stage G. SMI VIII correlated with Stage H.

For second molar, SMI I and II showed correlation with Stage D and E, respectively. SMI III correlated with Stage F and Stage IV and VI correlated with Stage G. SMI VII and VIII correlated with Stage H.

On the assessment of this relationship by calculating Spearman's rank correlation, the ρ value was 0.807 for canine, 0.837 for first premolar, 0.733 for second premolar, and 0.845 for second molar which indicated existence of a strong correlation for all locations. Second molar showed the maximum correlation [Table 2].

Table 2

Correlation between skeletal maturity indicator and grades of calcification at different locations (females)

Thus, in females, second molar calcification Stage D correlated with SMI I and Stage E correlated with SMI II. Second molar calcification Stage F correlated with SMI III. Second molar calcification Stage G correlated with SMI IV and SMI VI. Second molar calcification Stage H correlated with SMI VII and SMI VIII which infers second molar calcification Stage G represents prepeak of pubertal growth spurt and Stage H represents the peak of pubertal growth spurt.

DISCUSSION

The development status of an individual is usually assessed in relation to physical events that take place during the progress of growth such as skeletal ossification stages, the attainment of peak growth velocity, pubescent changes in the body, or dental calcification stages. Indicators of developmental age are, therefore, more informative than chronological age, particular for age estimation and clinical application.[10]

From this study, the relationship between the tooth calcification stages and the SMI probably allows the clinician to more easily identify the stages the pubertal growth period from the panoramic radiograph.

Many researchers have reported relationships between the calcification stages of individual teeth and skeletal maturity, as well as the racial variations.[11121314] A few studies are available in the literature about Indian populations. Therefore, the aim of this study was to investigate the relationships between the stages of calcification of various teeth and the stages of skeletal maturity among North-Indian patients using hand-wrist radiograph and panoramic radiograph.

In the present study, the grades of calcification were compared to the skeletal maturity by the maturation of the bones of the hand wrist. The assessments were done separately for both males and females. It was found that the bivariate correlation between tooth calcification and SMI (for males, ρ =0.58–0.75) [Table 1 and Graph 1] for females, ρ =0.73–0.84 [Table 1 and Graph 2]. Overall, the females showed more correlation between the tooth calcification and the SMI.

Graph 1

Correlation between skeletal maturational indicator stages and tooth calcification in males. (a) Canine. (b) First premolar. (c) Second premolar. (d) Second molar

Graph 2

Correlation between skeletal maturational indicator stages and tooth calcification in females. (a) Canine. (b) First premolar. (c) Second premolar. (d) Second molar

Many studies have attempted to determine whether there is a relationship between the level of skeletal maturity and the maturation of the permanent dentition. Demisch and Wartmann[15] reported a high correlation between dental and skeletal ages, Chertkow,[11] Coutinho et al.[16] Krailassiri et al.[12] and Engström et al.[17] reported similar high correlations. On the other hand, Lewis and Garn,[18] Garn and Lewis,[19] and Tanner[20] have reported low or insignificant correlations between the level of skeletal and dental maturation.

Statistically significant correlations were found between dental calcification stages and SMIs in Thai and Turkish patients.[1213] In this study, statistically significant correlations (for males ranging between 0.58 and 0.75, for females ranging between 0.73 and 0.84) [Tables 1 and 2] were found between dental calcification stages and skeletal maturity through hand-wrist radiographs. Thus, in this study, statistically significant correlations were obtained between dental calcification and SMIs similar to Thai and Turkish patients. Many studies reported that the high correlations between the tooth calcification stages and the SMIs probably allow the clinician to more easily identify the stages of the pubertal growth period from the panoramic radiograph.

Chertkow,[11] Chertkow and Fatti,[21] Sierra[22] and Coutinho et al.[16] suggested a high relationship between calcification of mandibular canine and SMI.

In this study, canines showed the maximum correlation with the SMIs in males [Table 1]. In females, second molar showed more correlation with the SMIs [Table 2].

However, in both male and female patients Thai individuals, the second premolar showed the highest correlation.

Mittal et al.[23] and Rai et al.[24] found second molar to be maximally correlating with the skeletal maturation in Indian patients. Same correlation was also found in the Turkish patients. In this study, female patients exhibited second molar to be maximally correlating with the skeletal maturation through hand-wrist radiographs [Table 2]. Thus, this finding is in accordance with studies conducted by Mittal et al.,[23] Rai,[24] and Uysal et al.[13]

Orthopedic treatment can be accomplished when the patient is in the stages of initiation and acceleration of growth as there is good amount of adolescent growth potential still left, i.e., before maximum pubertal spurt stages of SMI and tooth calcification. Around the peak pubertal stages, only some amount of growth can be utilized, probably fixed functional orthopedic treatment can be accomplished. After maximum pubertal stages, appliances can bring about only minimal skeletal changes and more of dental changes. Hence, during decelerating and completion stages, it is advisable to let the growth be completed and then advise the patient to undergo orthodontic treatment alone or surgical orthodontic intervention depending on the magnitude of the discrepancy.

CONCLUSION

General conclusions drawn from this study are as follows:

The appearance of each skeletal stage is consistently earlier in the females than in the males

The correlation between skeletal maturation evaluated by hand wrist and grades of calcification was found to be strongest for the canine in male patients and the second molar showed the strongest correlation in female patients

In malepatients, canine calcification Stages D and E corresponded to SMI I which signifies initiation of pubertal growth. Dental calcification Stage G corresponded to SMI III which signifies the prepeak of pubertal growth spurt or onset of peak height velocity (PHV). Dental calcification Stages G and H corresponded to SMI V which signifies peak of pubertal growth spurt, which infers that canine calcification Stages G and H represent the peak of the pubertal growth spurt

In females, first premolar and second molar calcification Stage D corresponded with SMI I which signifies initiation of pubertal growth. Calcification Stage E and F corresponded with SMI III which signifies the prepeak of pubertal growth spurt or onset of PHV. Dental calcification Stage G corresponded with SMI VI which signifies peak of pubertal growth spurt which infers dental calcification Stage G represents the peak of pubertal growth spurt. Calcification Stage H corresponded with SMI VIII. Thus, in females, calcification Stage G for both first premolar and second molar represents the peak of pubertal growth spurt

From this study, the relationship between the tooth calcification stages and SMIs probably allows the clinician to more easily identify the stages of the pubertal growth period from the panoramic radiographs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.