The sample consisted of 124 cephalograms of the total 311 patients examined clinically (male and female) with class I, class II, or class III malocclusion. Ninety patients fitted the criteria of the study, while 34 cases were excluded due to poor quality of cephalometric radiograph or failure to communicate with the patients. Among the selected cases 40% were male (36 cases) and 60 % were female (54 cases). These 90 cases were randomly divided into three groups, based on class I, II, III classification, with 30 cases in each group (Fig. 2).
The present study was conducted in patients who were seeking orthodontic treatment in the Orthodontic department of Shorsh teaching dental center in Sulaimani City. Ethical committee approval was obtained before starting the study (Appendix I).
Criteria For Selecting The Cases
1- Patients originating from Sulaimani Governorate, as ethnically verified by patient histories (all three grandparents of both parents were Kurdish and from Sulaimaniyah Governorate).
2- Patients aged between 18 and 28 years old.
3- Patients with complete permanent dentition including second molars.
4- No history of orthodontic treatment or orthognathic surgery.
5- No history of craniofacial trauma.
6- No cranial or facial malformation.
7- No TMJ disorder or pain.
When the patient came to the dental center seeking orthodontic treatment, informed consent was not taken for exposure to a lateral cephalogram, because a lateral cephalogram and orthopantogram is required as part of the routine diagnosis procedure.
Two finger method by Foster was used for the initial classification of the sagittal skeletal malocclusion (9). Then the researcher filled in the data recording sheet for each case (appendix II). After that, the patients were referred for a lateral cephalometric radiograph (ceph). All the cephs were taking by one radiologist. These cephs were obtained using the cephalogram [pax-i3D system (Pano-Cephalo-CT), 2014]. The machine was set at 84 kilovoltage peak (kVp), 10.0 milliampere (mA) and exposure time of 1.2 seconds (s). Cephs were taken with teeth in centric occlusion, lips in relaxed posture and the head in the natural head position with the Frankfort plane parallel to the floor (10).
Cephalometric landmarks and planes used in this study for analyses (3, 6)
S
The midpoint of the pituitary fossa (sella turcica).
M
The midpoint of the premaxilla, identified as the mid-point of the largest circle that could be drawn in the premaxilla tangent to the anterior and superior walls of the premaxilla.
G
Center of the largest circle tangent to the anterior, posterior and internal inferior surfaces of the mandibular symphysis.
Point A
The deepest midline point on the premaxilla between the anterior nasal spine and prosthion, near the apex of the central incisor root.
Point B
The deepest midline point of the bony curvature of the mandible.
Nasion (N)
In the frontonasal suture at the most anterior point.
C
Condylion, the midpoint of the condyle.
Functional occlusal plane
A line drawn through the region of the overlapping cusps of the first premolars and first molars.
ANB
SNA-SNB
Wits appraisal
horizontal distance between two lines, AO and BO, formed by drawing two lines perpendicularly from point A and point B to the functional occlusal plane.
Beta angle
The center of the condyle and point B are joined by C-B line. A perpendicular line is then drawn from point A to the C-B line angle. The Beta angle is the angle between this perpendicular line and the C-B line.
W angle
is formed by drawing a perpendicular line from point M to the S-G line.
After measuring the following variables: ANB, Beta angle and Wits appraisal, separately for each patient as shown in (Fig. 3A,B,C), the patients were classified into class I, II or III skeletal pattern groups, two of the three parameters were required to meet the same criteria and be within the same class (6). Table 1 shows the distribution of the patients who fulfilled the criteria across the class I, II, and III study groups.
Table 1
The criteria that included in the classes I, II, or III skeletal pattern for grouping of study
Skeletal class
|
ANB angle (11)
|
Wits appraisal (12)
|
Beta angle (13)
|
Class I
|
2° to 4°
|
Coincidence of AO and BO in females or BO 1 mm ahead of AO in males
|
Between 27o to 35o and clinically a pleasant (almost straight) profile
|
Class II
|
> 4°
|
AO ahead of BO in females or AO coinciding with or ahead of BO in males
|
< 27
|
Class III
|
< 2°
|
BO ahead of AO in females or BO ahead of AO by more than 1 mm in males
|
> 35°
|
All landmark identification and measurements were done with the use of the software program (Easy Dent 4, software version: 4,14,1 (2012)). This software program had options for adjustment of the radiograph by adjusting the contrast and brightness to facilitate the identification of the landmarks, in addition to zoom option and magnification for better viewing and differentiation of the landmarks. All the tracings were performed by the principal investigator (Mohammed sh).
After sample classification, W angle was constructed and measured (Fig. 4). According to Bhad et al. (6), W angle between 51–56 ° is considered as class I skeletal pattern, while an angle less than 51 ° is considered as skeletal class II relationship, and an angle greater than 56 ° is considered as skeletal class III (6).
To assess the reliability and reproducibility of the Ceph analysis, five parameters/variables from 10 randomly selected cephalograms were traced twice at a two- weeks interval by the same observer and were then tested by the paired t-test, with the mean differences in the measurements found to be non-significant. The inter-examiner reliability was assessed in the same way as for the examiners’ measurement and then tested using one way analysis of variance (ANOVA). No differences were found in the results.
Statistical analysis
The Statistical Package for Social Sciences (SPSS, version 22) was used for analyzing data. The Shapiro Wilk test was done to test the normality of the data. According to the P- values, the data were normally distributed. Hence, parametric tests such as ANOVA were used to compare the means of the three study groups. The post-hoc test was used to compare each two groups, Pearson correlation coefficient (r) was used to assess the strength of correlation between two numerical variables, and coefficient of variability was used to measure the extent of variability of the variable in relation to the population. The significance alpha level was set at p value of ≤ 0.05.