Establishing Cephalometric Norms in Primary Dentition Using Comprehensive Craniofacial Growth Analysis - A Digital Cephalometric Study

ABSTRACT Objective: To establish cephalometric norms in primary dentition among males and females using novel customized Comprehensive Cephalometric Growth (CCG) Analysis. Material and Methods: The study was conducted on 67 subjects with a mean age of 5.5 yrs. Digital lateral cephalometric radiographs were obtained using Planmeca Pro One. The digital images were then transferred to Nemoceph software. Craniofacial Growth (CCG) Analysis was configured in the software with five sub-groups. This sub-grouping was done such that related components were grouped together and comprehensively; it would provide an assessment of every component of the craniofacial region that could be affected either by treatment maneuver or growth process. The same was used for the cephalometric analysis and to determine the cephalometric norms in the primary dentition. Results: Certain linear measurements were higher among males when compared to females. However, most measurements remained similar among males and females during this age group. The CCG analysis provided a comprehensive knowledge of the craniofacial parameters during the growth process. Conclusion: The cephalometric norms during primary dentition thus established using Comprehensive Craniofacial Growth analysis would provide the data for early diagnosis and treatment planning in interceptive orthodontic treatment procedures.


Introduction
Post-natal growth covers the period from infancy through adolescence, and it is assumed that during this span, almost 100% of adult dimensions are achieved [1].However, the growth occurring during this period is not continuous and exponential.Different parts of the body grow at different times and at different rates.The rate of growth tends to increase from the cephalic to the caudal end.The same dynamic trend is applicable in the craniofacial region as well.According to Scammon's growth curve, the growth and development of cranial structures follow the neural curve, with the cranial vault achieving 95% of adult size by 5 years of age, followed by which there is a deceleration in the growth rate.In children, these changes can be well appreciated from the facial profile as a large forehead, smaller nasal part due to the correspondingly less respiratory demand and more growth changes occurring in the mandible compared to maxilla leading to the final facial type after growth completion [2].
The transition from primary to mixed dentition and from mixed to permanent dentition has a significant effect on the facial profile [3], and this transition remains a continuous process.Studies have indicated that their significant changes in the craniofacial growth pattern can be appreciated in two phases.The first period was during the 5 to 7 years of age, corresponding with the transition from primary to early mixed dentition period.
The second period was during 10 to 13 years of age corresponding with the transition from late mixed to permanent dentition period [4].Many cephalometric studies have been reported for the mixed dentition period [5][6][7][8]; however, the studies emphasizing the craniofacial norms on primary dentition are meager.
With more emphasis on early diagnosis and treatment planning, there is a need to identify the developing malocclusion at the earliest.To identify the developing malocclusion, it is essential to have the norms well defined so that any deviation from the norms can be diagnosed and considered for treatment.Not only for treatment planning, but these norms are also required to predict growth changes as well.Hence this study was conducted to establish cephalometric norms in primary dentition with the use of novel integrated, comprehensive, customized cephalometric growth analysis.
This study utilized this integrated growth analysis as this focused on all aspects of the craniofacial growth comprehensively compiled in the single analysis, which can be further utilized in the follow-up of the craniofacial growth.

Study Design and Sample
In this observational study, the craniofacial parameters were assessed on 67 subjects of the regional Indian population (38 males and 29 females) with a mean age of 5.5 years.Since the outcome measure was quantitative, the sample size was determined based on a comparison of means (a comparison of means was done here as this data is part of a longitudinal study comparing primary and mixed dentition).A pilot study was conducted to determine the means.
At 95% confidence and 80% power of study, the sample size was determined using the formula for comparison of means.Children less than 6yrs of age with complete primary dentition, no gross facial asymmetry and balanced facial profile as observed on extraoral examination were included in the study.The anthropometric measurements (height and weight) were considered and subjects belonging to extreme measurements as per the growth chart were excluded from the study.Subjects with a history of previous orthodontics treatment, rampant caries, syndromes and defects involving craniofacial region were also excluded from the study.

Data Collection
Before the examination, ethical clearance was obtained from the Institutional Ethical Board.Then, an initial clinical examination was done and children satisfying the above-mentioned inclusion criteria were selected.
The parents were explained about the study and procedures to be performed during the study.The possible advantages and effects were also explained.Only the children whose parents had provided informed consent and children providing informed assent were included.
Standardized Digital lateral cephalometric radiographs were obtained from the participants with Planmeca Pro One (Planmeca OY, Helsinki, Finland).The Planmeca imaging was provided with Romexis software.This software was used for image enhancement and the thus obtained image was converted into Jpeg format and imported into the Nemoceph Software version 10.4.2 for further analysis (NemoTec, Madrid, Spain).
After calibration, anatomic landmarks were located in the Nemoceph software (Figure 1), and cephalometric analysis was done with a novel customized analysis for craniofacial growth -Comprehensive Craniofacial growth (CCG) analysis.All the measurements were performed only in the software; no manual measurements were made.This analysis was customized and comprehensive the analysis was grouped as follows: A. Upper Craniofacial Measurements; B. Lower Craniofacial Measurements; C. Upper/Lower Craniofacial Measurements; D. Dental Measurements; and E. Cephalometric Soft tissue measurements.The above-mentioned measurements and their significance have been described in Tables 2 to 6.

Figure 1. Anatomic landmarks.
A single examiner performed all the cephalometric analyses.The images were calibrated before the location of the cephalometric landmarks.The intra-operator reliability coefficient was obtained for each parameter to assess the intra-observer reliability.A set of five subjects were assessed on different parameters at three different times.Most of the parameters measured had intra-observer reliability above 95% (Table 1).
Following this, the tracing was performed.The analysis measurements thus obtained were exported from the software in txt format and tabulated in an Microsoft Excel spreadsheet.Tweed's Analysis [13] 6 Interincisal Angle Ī-ḻ The interincisal angulation relates the relative position of the maxillary incisor to that of the mandibular incisor.
Downs Analysis [14] Table 6.Definitions of the linear and angular measurements: soft tissue measurements.

Data Analysis
The data obtained from the cephalometric analysis was then exported and tabulated in an Excel sheet.
Finally, an independent sample t-test was applied to compare boys and girls.The level of significance was set at p=0.05.

Results
Table 7 describes upper craniofacial measurements during primary dentition among males and females.
Among the parameters assessed in the upper craniofacial region, the sagittal growth at ANS showed a significant difference among males and females, with females having higher sagittal growth.However, the other linear and angular measurements remained almost similar among males and females for the age group under assessment.
Table 8 describes lower craniofacial measurements during primary dentition among males and females.
Among the lower craniofacial measurements, the ramus height was significantly different in males and females, with males having a mean value of 38.74 mm compared to females, which was 35.79 mm.Among the angular measurements, SNB was statistically higher among females.Table 9 describes upper/lower craniofacial measurements during the primary dentition stage among males and females.The facial height, both total and posterior facial height was higher among males when compared to females.This difference was statistically significant.The mandibular inclination was also found to be higher among males.Table 10 describes dental measurements during primary dentition among males and females.The incisor mandibular plane angle (IMPA) was found to be significantly higher among males.

Discussion
The craniofacial growth and development is a complex interplay of events that may not follow a uniform line and is rather a time and magnitude based.There are various milestones in craniofacial growth.The primary dentition stage is a stable phase of dentition expressing well-defined growth parameters [17].
It is essential to define these parameters comprehensively during this phase to identify the deviation from normal at the earliest.These should also necessarily include the soft tissue parameters, as the assessment of the facial balance would be incomplete if facial soft tissue characteristics are not considered, as overlying soft tissue drapes may not always follow the underlying skeletal framework.Furthermore, facial treatment outcomes may not be satisfactory if the approach is based only on dental and skeletal parameters [18].Hence this article describes a comprehensive analysis that would define the growth parameters during the initial stage of craniofacial growth and development.
Though the norms discussed in this study cannot be generalized to all the population as the study was conducted on the Indian regional population, the availability of such data can be considered for the purposes of comparison as the studies describing the cephalometric norms of regional populations are very meagre.
Therefore, the analysis emphasizes the growth-related parameters that have been identified and grouped.This provides a platform for the craniofacial biologist to gather related information easily using this tool.In this analysis, the linear and angular measurements are grouped such that individual groups themselves can be used as an analysis.
This study was conducted to establish cephalometric norms of primary dentition for the regional population and to introduce the comprehensive cephalometric analysis, which can be used effectively to determine the cephalometric parameters, particularly among growing children.
Sixty-seven subjects satisfying the previously mentioned inclusion and exclusion criteria were included in the study.Standardized lateral cephalometric radiographs were obtained with Planmeca Pro One.Nemoceph software (version 10.4.2) was used for the cephalometric analysis, which provided accurate and quicker measurements.However, this process required calibration of the images before performing the analysis.
On each cephalometric radiograph, 25 skeletal and 12 soft tissue landmarks were identified.From the cephalometric landmarks and reference lines, 16 angular and 34 linear measurements were analyzed.All the landmarks selected were configured in a separate analysis named Comprehensive Craniofacial Growth Analysis.
This was a customized, comprehensive configuration performed in the Nemoceph Software.The analysis had the related components of the craniofacial region grouped together to derive effective outcomes.This analysis is comprehensive as it describes not only the hard tissues but also the soft tissues parameters to accurately identify the discrepancy.Although this study does not compare the growth changes, this analysis was named "Comprehensive Craniofacial Growth Analysis" because this tool can effectively be used for research and assessments related to craniofacial growth.
Literature reports only a few studies describing the cephalometric norms for primary dentition [19][20][21].However, the measured variables showed variation in facial dimensions compared to the present study.
These differences are attributed to the racial differences present in the population studied.Moreover, a difference existed in the reference points as well.
Hence this demands a need for a systematic, comprehensive cephalometric analysis.This article emphasizes this analysis and also describes the cephalometric norm of primary dentition for the regional population.This analysis would provide the standardized baseline for diagnosing the malocclusion at the earliest and treating them accordingly as a treatment performed during the growth is considered more stable.It has been reported that more than 50% of malocclusion appears during the transition from primary to mixed dentition, which emphasizes the need for early orthodontic intervention [22].
This study further compares the dimensional differences in primary dentition among males and females.
Most parameters were similar among males and females in this age group.However, certain variables like total facial height, posterior facial height, ramus height and mandibular inclination were higher among males.Similar observations were also reported by Suh et al. [21].

Conclusion
This paper describes the Comprehensive Craniofacial Growth (CCG) Analysis as a novel unique analysis method that can be incorporated for cephalometric analysis, particularly for interceptive orthodontic procedures to be performed during the primary and transitional dentition period.In addition, this analysis has further subgroups which can be used individually if the area of interest remains specific.Most craniofacial parameters assessed in primary dentition were similar among males and females except for certain linear measurements, which were higher among males.
the horizontal position of the maxilla relative to the cranial base.

FH
Plane-Lower IncisorDetermines the degree of balance and harmony between the lower face and anterior limit of the dentition Tweed's Analysis[13] 4Incisor Mandibular Plane Angle (IMPA)Lower Incisor-Mandibular PlaneDetermines the balance and harmony in the lower facial profile.Due to the effect of lower incisors on facial esthetics and stability, it is considered a determinant of balance in lower facial harmony.Tweed's Analysis[13] determines the inclination of the upper central incisor relative to the anterior cranial base.

Table 7 . Comparison of upper craniofacial measurements during primary dentition among males and females.
*Statistically Significant.

Table 8 . Comparison of lower craniofacial measurements during primary dentition among males and females.
*Statistically Significant.

Table 9 . Comparison of upper/lower craniofacial measurements during primary dentition stage among males and females.
*Statistically Significant.

Table 10 . Comparison of dental measurements during primary dentition among males and females.
*Statistically Significant.

Table 11
describes soft tissue measurements during primary dentition among males and females.The differences in soft tissue parameters among males and females, although existed were not statistically significant.