Assessment of the patient’s puberty and developmental events is one of the most basic and important elements in orthodontic treatment. Information regarding the pubertal growth spurt of the patients plays a significant role in the diagnosis, objectives, and selection of the treatment method (Krailassiri et al. 2002). The use of hand-wrist radiographs has been advocated in order to assess the skeletal age of individuals. Several human growth studies (Flores-Mir et al. 2006; Houston et al. 1979; García-Fernandez et al. 1998; Uysal et al. 2004) have shown that the timing of the pubertal growth of the craniofacial region is closely related to specific ossification events and stages observed in the hand-wrist area of the skeleton, therefore, hand-wrist radiographs have been proved to be a valuable diagnostic tool in orthodontics. However, these radiographs can cause unnecessary exposure to the patient. Thus the ALARA principle is important especially for children and young adults, as high radiation methods are not advised to be used frequently for the assessment of growth. The ease of distinguishing the stages of dental development and the availability of panoramic radiographs are practical reasons for attempting to assess the physiologic maturity without resorting to hand-wrist or lateral cephalometric radiographs (Krailassiri et al. 2002).
In previous radiographic studies, authors have used either mandibular third molars (Engström et al. 1983), premolars (Şahin Sağlam and Gazilerli 2002), canine (Yadav et al. 2017) or maxillary canine (Kumar et al. 2017) for the assessment of skeletal maturation, which exhibited certain drawbacks. Root formation and apex closure of canines and premolars usually completes by the age of 12 to 14 years, however most of the children exhibit active growth up to the age of 16 to 17 years. Third molars, on the other hand, are the most commonly missing teeth in the human dentition, making them unreliable for the age assessment. The current radiographic study, which has been conducted to evaluate the reliability of different developmental stages of mandibular second molars as an indicator of maturity. Mandibular second molar tooth offers an advantage over other teeth because of its developmental stages, which tends to continue over a longer period and later age. Apex closure of mandibular second molar generally extends up to the age of 16 years in normal children, which makes it more reliable in the assessment of growth. In the present study, mandibular second molar has been taken as a sample instead of maxillary molar and canine in order to eliminate the errors of estimation caused by roots of these teeth, which can overlap with the anatomic structures such as palate, inferior border of zygomatic arch, maxillary sinus septum etc. (Vijayashree et al. 2014).
It has long been opposed that dental eruption, which is the most conspicuous and easily determined indicator of dental maturation, is much more variable in its timing than skeletal maturation (Nolla 1960; Van der Linden et al. 1979). According to Nolla (Nolla 1960), dental eruption has also been reported to be more variable than the calcification sequence in the dentition. Dental eruption is a fleeting event that is under greater environmental influence (Demirjian et al. 1973). In the present study, calcification stages of teeth, rather than eruption, were preferred because tooth formation is proposed as a more reliable criterion for determining dental maturation (Nolla 1960). Therefore, the dental maturity assessment stages of Demirjian et al. (Demirjian et al. 1973), were used. This method also shows high accuracy when applied to Indian populations (Rai et al. 2008).
Since the system of evaluating hand wrist radiograph has been found to be valid in both clinical and research situations, include eleven discrete adolescent skeletal maturational indicators, covering the entire period of adolescent development, are found in hand wrist, and seven, out of these eleven discrete, occur in the third finger. Therefore the current study utilized the use of the middle phalanx of third finger of the right hand. Developmental changes in the middle phalanx of the third finger has been used to study the skeletal maturity development, as they follow the pubertal growth spurt from the onset to the end (García-Fernandez et al. 1998). Keeping in mind the ALARA principle, no additional exposure to radiation would be necessary if skeletal maturity can be assessed through routinely taken radiographs. The high degree of clarity and availability of the intra-oral periapical radiographs, the ease with which one can interpret the modified MP3 skeletal maturity stages, the low cost of IOPA films and the minimal radiation exposure point etc. make it a practical technique for the dental professional for the growth assessment.
The current study revealed a positive correlation between mandibular permanent second molar and modified MP3 which was in accordance to studies done by Vijayashree et al. (Vijayashree et al. 2014), in a South Indian population, who found highly positive correlation between DI of mandibular second molars and CVMI modified method. Perinetti et al. (Perinetti et al. 2011), analyzed the diagnostic performance of the circumpubertal dental maturation phases for the identification of individual-specific skeletal maturation phases and found that the dental and skeletal maturity are highly correlated, although the diagnostic performance of dental maturity for the identification of any stage of skeletal maturity is limited. Uysal et al. (Uysal et al. 2004), investigated the relationships between the stages of calcification of various teeth and skeletal maturity stages among Turkish subjects and suggested that tooth calcification stages from panoramic radiographs might be clinically useful as a maturity indicator of the pubertal growth period. According to them, it is appropriate to put these skeletal and dental maturation relationships into daily orthodontic diagnostic practice, when treating a patient. Kumar et al. (Kumar et al. 2011), in a north western Indian population found a highly significant association exists between DI and CVMI. According to them, mandibular second molar DI stages are reliable indicators of skeletal maturity. Krailassiri et al. (Krailassiri et al. 2002), in a Thailand population found that tooth calcification stages from panoramic radiographs might be clinically useful as a maturity indicator of the pubertal growth period. Rai et al. (Rai and Anand 2007), investigated the relationship between the stage of calcification of various teeth and skeletal maturity stage among Indians and suggested that tooth calcification stages from panaromic radiographs might be clinical useful as a maturity indicator after pubertal growth period, despite them using either mandibular canine, premolars or second molars in their studies.
The unique and significant findings from the present study imply that the stages of mandibular second molar calcification as observed on panoramic radiographs provide fairly accurate results and can be considered reliable indicators of skeletal maturity with the methodology suggested by Demirjian et al. (Demirjian et al. 1973).
