Treatment during periods of accelerated or intensive growth can contribute significantly to correction of dent facial deviations and improvement of facial appearance. Most of the patients requiring orthodontic treatment are growing individuals [1]. The orthodontist must know about the growth status of the patient, whether patient has attained the peak pubertal growth or moved from that point. This in turn determines, whether growth modification still can be carried out [2]. It has been proposed that growth modification treatment for the maxilla (e.g., with protraction headgear) should be started before the peak pubertal growth of the maxilla, whereas growth modification for the mandible (e.g., functional appliances for Class II) has been shown to be more effective during or slightly after peak mandibular growth [3-5]. Treatment of facial growth is also important for planning orthogenetic surgery. Individual growth time varies from person to person, because everyone has his/her own biologic clock [6]. Treatment planning and retention decisions are influenced by the amount of remaining growth, necessitating a need to accurately assess level of skeletal maturity [7]. Skeletal maturation is the degree of development of ossification in the bone. Various maturity indicators are used to assess growth spurt and these methods include sexual maturation characteristics, dental development, chronologic age, body height, body weight, and menarche and voice changes. But these methods need serial recording and assessment of some pubertal markers which is not practically feasible. Indeed, the clinical applicability of chronological age as an indicator of the onset of pubertal growth spurt in the individual patient is limited, as the growth spurt is influenced by several other factors including genetics, ethnicity, nutrition & socioeconomic status [1]. Though hand wrist radiograph have been used to assess peak pubertal growth spurt, there exist some limitations in the interpretation of skeletal maturity from hand wrist radiograph [2]. The ossification sequence and timing of skeletal maturity with hand wrist radiograph show polymorphism and sexual dimorphism which can limit the clinical predictive use of this method [3-5]. Still there are concerns about extra radiation exposure [6] and the British orthodontic society guideline stated that the use of hand wrist radiograph to predict the onset of pubertal growth spurt was not indicated [7]. Finally events in the hand and wrist are indicators of the peak and the end of the pubertal growth spurt, but these events do not signal the onset of the pubertal growth spurt [1]. Because of this cervical vertebral maturation (CVM) has been evaluated for its correlation to the skeletal maturity as an alternative to hand wrist method [2-5]. Pancherz & Szyska found that the cervical vertebral maturation method has level of reliability comparable to hand and wrist method [6]. Grave & Townsend also have confirmed the validity of CVM method in Australian aborigines [7]. No additional radiograph is necessary if pubertal growth assessment is done on a lateral cephalogram (which is a routinely requested radiograph, for orthodontic treatment planning [1]. bearing in mind the “As low as reasonably achievable” LARA principle.) The latest method by Baccetti et al [2] is further simplified to include only second through fourth vertebrae so that it can be useful even with a protective collar. According to him, definitions of stages were not based on a comparative assessment of between-stage changes, so that stages can be identified easily on a single cephalogram [3]. Furthermore, it has been shown that the effective radiation dose for a lateral cephalogram without a thyroid shield is 1.5 fold higher than the effective dose for a lateral cephalogram with a thyroid shield plus a hand-wrist radiograph [4]. The most useful method to evaluate Biologic maturity is the estimation of the skeletal age due to the fact that the changes that bone experience during their maturational process are very similar in all individuals and each ossification center goes through a number of morphological changes that can be easily identified. CVM method has been proposed to be effective & correlates with statural growth, mandibular growth spurt and other levels of growth biomarkers [4-7]. Similar to gingival reticular fluid alkaline phosphatase evaluated by Perinetti et al. Since the CVM is advocated as a timing tool for orthopaedic treatment, its diagnostic accuracy and activity repeatability should be assessed. The present study was designed to address, if the visual assessment of the CVM stage was accurate and repeatable. If disagreement is seen, how is this structured among the different stages? This study ultimately aims to evaluate the diagnostic accuracy and repeatability of the visual assessment of the cervical vertebral maturation (CVM) stages.

This study was a retrospective validation study consisting of 100 randomly selected patients seeking orthodontic treatment in the Department of Orthodontics and Dent facial Orthopedics of our institution. Inclusion criteria were patients in the age group between 8 to 18 years, with no general developmental anomaly, no congenital anomalies of the second, third, and fourth cervical vertebrae, no significant medical history that would affect physical development and growth, no history of trauma at the cervical region, and patients of Indian ethnicity. Patients with lateral head films of low quality were excluded. Care stream 5700 laser imager system with digital cephalostat was used to take the lateral cephalometric, radiographs. Digital cephalogram was taken with functional head positioner. Patient was made to stand in natural head position stabilized by ear rods and nation pointer. A standardized source to mid-sagittal plane distance of 152.4cm (5 feet) and a detector to mid-sagittal distance of 11.5cm (Figure 1).

Figure 1:  Patient in Position for Cephalogram.

A total of 10 operators underwent training session in visual assessment of CVM staging using a series of cases analyzed cephalometrically (reference standard). Subsequently, they were asked to assign stage in a different set of cases at baseline (T₁) and again after 4 weeks (T₂). The outcomes of these sessions were compared with the reference standard (objective analysis) and for diagnostic accuracy. Initial samples of more than 100 subjects were screened to obtain a total of 96 subjects (51 girls and 45 boys) for the study. These 96 subjects were equally divided into the six CVM stages according to the cephalometric analysis. Within each CVM stage, 6 cases (total, 36 cases) were used for the training sessions; the remaining 10 cases per CVM stage (total, 60 cases) were used for the diagnostic accuracy and reproducibility part of the study. In particular, these 96 cases were selected according to the outcome of the cephalometric analysis.

Figure 2: Digitized Cephalogram Showing CS6.

All the lateral cephalograms were cropped to include cervical vertebrae C₂ to C₄ and to eliminate any additional information. 10 operators equally derived from four different universities were involved in the study. Among these operators five were postgraduate students, one intern, three assistant professors, and one undergraduate student. CVM method was instructed to the raters by an expert researcher. Every rater underwent two training sessions in the CVM staging. A series of 36 cases were used to instruct the raters with the, digitized cephalograms (Figure 2) for every stage and the numeric data according to Biscotti et al [1]. All cephalograms were traced by an operator and checked for accuracy by a second investigator. Rules for assigning CVM stages were explained; each rater was instructed to assign a stage to each of the traced cases (Figure 3) visually and blinded, based on identification of concavities at C₂, C₃, and C₄ and subsequently, assignment of shapes of C₃ and C₄.

Figure 3: Cropped Tracing Showing CS5.

After a first assignment, the raters were allowed to see the superimposed cervical tracings and the numeric data of the cephalometric analysis. Conflict of any type was discussed immediately. Each rater was provided with the files with images and numeric data, after the end of this first training session. After a period of four weeks the raters underwent another session of training. Second session of training was conducted by a different instructor with the same protocol. In the second session of training, cephalograms were randomly ordered different from the first session. And training was thought to be successful only if at least 80% of the cases were correctly identified. Those raters failing to reach this result underwent a further session of training a week later. CVM Method used for the training and assignment of stages was the most recent CVM method, as proposed by Biscotti et al 28 including six stages: two prepubertal (stages 1 and 2), two pubertal (stages 3 and 4), and two post pubertal (stages 5 and 6) was used. When apparent disagreement was seen between the presence of concavities at the lower borders and the shapes of the cervical vertebrae, the most mature stage of either the concavities or shape was assigned. Cephalometric software (Dolphin Imaging 10.5 Premium) was used for all cephalograms examined in this study. After a thorough and successful training these operators were allowed to visually analyze the cephalogram and assign the cervical vertebral maturation stage for each individual cephalogram. Which were presented randomly ordered for the two sessions.

Two sets of variables were analyzed

• Presence or absence of a concavity at the lower border of the body of C₂, C₃, and C₄; and
• Shape of the body of C₃ and C₄. Four basic shapes were considered Trapezoid, Rectangular horizontal, Square, Rectangular vertical.

In CVM Stage 1, T₁ session of assessment had 90.0% agreement and T₂ sessions of assessment had 100% agreement none of the sample showed any disagreement in T₂ session.

In CVM Stage 2, T₁ session had 80.0% agreement and T₂ session of assessments had 100% agreement, none of the scan showed any disagreement in T₂ session.

In CVM Stage 3, T₁ and T₂ assessments had 90.0% agreement; only one scan (10.0%) showed disagreement in both T₁ and T₂ sessions.

In CVM Stage 4, T₁ and T₂ assessments had 90.0% agreement; only one scan (10.0%) showed disagreement in both T₁ and T₂ sessions.

In CVM Stage 5, T₁ and T₂ assessments had 60.0% agreement; a total of 4 scans (40.0%) showed disagreement in both T₁ and T₂ sessions.

In CVM Stage 6, T₁ session had 60.0% agreement and T₂ assessments had 90.0% agreement; only three scans (30.0%) in T₁ and one scan (10.0%) in T₂ showed disagreement.

Overall for all CVM Stages, T₁ session had 80.0% agreement and T₂ session of assessments had 88.3% agreement; a total of 12 scans (20.0%) in T₁ and 7 scans (11.7%) in T₂ sessions showed disagreement.

The distribution of disagreement was relatively higher for CM stage 5 in both the recording sessions T₁ and T₂.

The data on categorical variables is presented as n (% of cases) and the values on continuous variables is shown as Means for each recording sessions T₁ and T₂. The statistical significance of difference of categorical variables was tested using Chi-Square test or Fisher’s exact probability test. The statistical significance of inter-group difference of mean values was tested using unpaired t test after confirming the underlying normality assumption. The indices of diagnostic efficacy such as sensitivity, specificity, PPV, NPV and accuracy were calculated for each recording session separately. The precision of accuracy was assessed using 95% CIs. Cohen’s Kappa statistic was used to study the agreement of assessments with the reference stages at each recording session and for each observer (rater) separately. Kendall’s W statistic was used to study the concordance for inter-rater agreement with the reference standards in each recording session.

According to literature, treatment timing plays an important role in the results of nearly all dent facial orthopedic treatments for all dent skeletal disharmonies in growing patients [1]. The skeletal maturation of a child aids in evaluating how much growth still remains and whether the pubertal growth spurt (PGS) has been reached or completed. Because of the variation in the timing of PGs, chronologic age is not a valid indicator of skeletal maturation. With many orthodontic patients, pubertal growth needs to be factored into the diagnostic equation. The main goal of functional therapy of mandibular deficiencies is to induce supplementary lengthening of the mandible by stimulating increased growth at the condylar cartilage. Therefore, the evaluation of mandibular skeletal maturation and growth potential in the individual patient provides essential information for the anticipation of treatment results. Orthopedic treatment of patients with class III malocclusion and rapid maxillary expansion also benefits from the identification of the optimal timing to achieve maximum efficacy, which in these cases is at a pre-pubertal growth phase. Therefore, the correct identification of the different phases of skeletal maturation represents a crucial issue (Table 1).

Table 1: Distribution of overall agreement with the reference standard According to the recording sessions T1 and T2 (n = 60).

Numerous methods have been proposed to assess biologic maturity. Chronologic [2] and dental ages [3] are considered poor indictors of skeletal and craniofacial maturity. Skeletal age, as assessed by hand-wrist radiographs [3], provides an accurate determination of biologic maturity. However, this method requires additional radiograph. Recently, the use of cervical vertebral maturation (CVM) has gained increasing interest as a valid replacement for hand-wrist evaluation. Furthermore it also prevent patient from extra radiation exposure [4]. In terms of the accuracy and repeatability some controversy exists, some researchers have questioned the repeatability of CVM method, which should not be underestimated. Therefore the objective of this study was to evaluate the diagnostic accuracy and repeatability of visual assessment of CVMM. Nest man (2011) studied CVMM and the principal finding of their study showed interobserver agreement to be high for assessing the lower borders of C₂, C₃, and C₄ as either flat or curved, but inter-observer agreement was low for assessing the vertebral bodies of C₃ and C₄ as either trapezoidal, rectangular horizontal, square, or rectangular vertical hence according to them, this leads to the overall poor reproducibility of the CVMM. The reproducibility of the CVM method was recently assessed by Gabri el et al who attempted to use methods to “eliminate the methodological shortcomings of previous studies”. In that study, the authors found that interobserver agreement for CVM staging among practicing orthodontists was below 50%; on average, the clinicians agreed with their own staging only 62%of the time (ranging from a high of 80% for 1 clinician to a low of 43% for 2 clinicians); and the reproducibility of trained clinicians was significantly below the level reported in the literature. In our study, overall for all CVM Stages, T₁ session had 80.0% agreement and T₂ session of assessments had 88.3% agreement; a total of 12 scans (20.0%) in T₁ and 7 scans (11.7%) in T₂ sessions showed disagreement. The distribution of disagreement is relatively higher for CM stage 5 in both the recording sessions T₁ and T₂. The distribution of extent of agreement or disagreement did not differ significantly between two sessions of assessment (P-value>0.05 for all). In study by Kucukkeles et al, when 2 of 3 intra-observer tests of reproducibility were 45% and 65%. Most of those who cited high reproducibility results, however, used tracings of the cervical vertebrae instead of the actual radiograph during the CVM staging process. In our study, we avoided bias by having the observers stage the lateral cephalogram images directly, not from tracings of cervical vertebrae as in previous studies [4]. Second, we had a panel of 10 operators with no knowledge of the design of the study and who received standardized training in the CVM method with Exact reference materials according to Biscotti et al. In several previous studies, the authors themselves performed the inter-observer and intra-observer tests of reproducibility. The sample used in the study by Nest man and Marshal (2011) 55 was the same sample used by Gabriel et al, which was from randomly selected samples, but in our study we randomly selected lateral cephalograms from subjects in the circumpubertal age range. This sample provided a unique look at the varied ranges of CVM scores assigned to these subjects.

According to Xiao and colleagues the factors that affect the accuracy and repeatability of CVM are:

The ‘‘measurements’’ are purely subjective. It is difficult to exactly define and identify the gradual appearance of the concavity in the inferior border of the vertebral bodies. So, the difference between horizontally rectangular, square, and vertically rectangular shapes depends on the researcher’ arbitrary decision.

The shapes of cervical vertebrae show marked variation from subject to subject. Sometimes the shape and inferior borders of C₂–C₄ cannot fulfill the definition of a cervical stage at the same time. To avoid the above said bias in the present study, we instructed all the raters to assign the most mature stage among concavity or shape of the vertebrae.

For stage 5, the mean deviation of no. of stages from the reference standard is relatively higher than the other CVM stages which was 0.40 both in T₁ and T₂ then follows stage 6, the mean deviation of no. of stages from the reference standard is 0.30 in T₁ and 0.10 in T₂ for stage 6. The distribution of mean deviation did not differ significantly between two recording sessions (P-value>0.05) for both stage 5 and 6.

In our study intraobserver agreement with reference standard increased from T₁ to T₂. Hence we found the repeatability of visual assessment of CVM method to be good. Hence, it can be concluded that visual assessment of cervical vertebral maturation is accurate and repeatable, if good training in CVM method is followed. A study with a larger sample size on Indian population would be helpful to further evaluate the accuracy and repeatability of visual assessment of CVMM.

According to the present results of this study which shows that the visual assessment of CVM method to be accurate and repeatable. But there is a need of proper training sessions. This accuracy appears independent of the rater’s own experience in orthodontics. However, to avoid unreliable diagnosis, more careful assessment of CVM stages 5 and 6 should be done. After a thorough knowledge about the assignment of CS visually, the CVM method proves to be accurate and repeatable to a satisfactory level.

The authors declare that they have no conflict of interest.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and MUHS research committee. Acknowledgements: I would like to express my sincere gratitude to my mentor and guide Dr. Ajit Kalia (HOD and Professor, department of orthodontics, M.A. Rangoonwala College of Dental Science and Research Centre, Pune) who provided inspiration and guidance behind the idea of the study.

1. Kamal AT, Shaikh A, Fida M. Assessment of skeletal maturity using the calcification stages of permanent mandibular teeth. Dental Press J Orthod. 2018; 44: 1- 44.
2. Szemraj A, Slominska WA, Pilszak RB. Is the cervical vertebral maturation method effective enough to replace the hand-wrist maturation method in determining skeletal maturation A systematic review. Eur J Radiol. 2018; 102: 125-128.
3. Morris KM, Fields HW, Beck FM, Kim DG. Diagnostic testing of cervical vertebral maturation staging: An independent assessment. Am J Orthod Dentofacial Orthop. 2019; 156: 626-632.
4. Hosni S, Burnside G, Watkinson S, Harrison JE. Comparison of statural height growth velocity at different cervical vertebral maturation stages. Am J Orthod Dentofacial Orthop. 2018; 154: 545-553.
5. Perinetti G, Primozic J, Sharma B, Cioffi L, Contardo L. Cervical vertebral maturation method and mandibular growth peak a longitudinal study of diagnostic reliability. Eur J Orthod. 2018; 40: 666-672.
6. Cunha AC, Cevidanes LH, Anna SEF, Guedes FR, Luiz RR, McNamara JA et al. Staging hand-wrist and cervical vertebrae images a comparison of reproducibility. Dentomaxillofac Radiol. 2018; 47.
7. McNamara JA, Franchi L. The cervical vertebral maturation method a user's guide. Angle Orthod. 2018; 88: 133-143.