Sagittal and vertical occlusal cephalometric analyses of Pancherz: Norms for Chinese children

Introduction

The aims of this research were to establish norms for the sagittal and vertical occlusal cephalometric analyses of Pancherz for Chinese children and compare them with those of a matched white sample.

Methods

The material comprised lateral cephalograms of a random sample of 405 southern Chinese children (age, 12 years; 200 boys, 205 girls) and an additional sample of 86 British white children (age, 12 years; 43 boys, 43 girls) in Hong Kong. The radiographs were digitized twice.

Results

Statistically significant sex differences were found for 9 of 11 parameters in the sagittal occlusal analysis, and 6 of 10 in the vertical occlusal analysis in the Chinese sample, whereas there were no sex differences in the sagittal occlusal analysis and only 2 differences in the vertical occlusal analysis in the white sample. Statistically significant ethnic differences were found for 5 parameters in boys and 8 in girls of the 11 parameters in the sagittal analysis. For the vertical analysis, 7 of 10 parameters in both sexes differed significantly.

Conclusions

For the sagittal and vertical occlusal analyses of Pancherz, separate sex-specific standards are needed for Chinese and white children.

The Pancherz and pitchfork cephalometric analyses are commonly used for the evaluation of treatment changes. In a contemporary comprehensive textbook on cephalometry, a list of the most well-known and popular cephalometric analyses included no fewer than 23 analyses introduced between 1946 and 1985. Other analyses by Pancherz, Johnston, Hack et al, and Cooke and Wei were not included.

The dentofacial morphology of subjects with Class II pattern has been compared by using Pancherz method in a number of recent studies. The Pancherz method has been used not only for evaluation of treatment, but also for comparison of dentofacial morphology. However, there are no norms or reference values in that analysis with which patient samples can be compared to determine the relative severity of their dentofacial problems. Separate norms for Chinese and white patients are necessary, since there are marked differences in dentofacial morphologies between the 2 ethnic groups.

The Pancherz cephalometric analysis comprised 2 parts, the sagittal occlusal analysis (SO anlysis ) and the vertical occlusal analysis (VO analysis ), which make it possible to distinguish between sagittal and vertical dentofacial problems and changes. The SO analysis includes 11 linear variables, and the VO analysis has 6 linear and 4 angular variables. Hence, 17 of the 21 parameters are linear. Linear measurements are more reliable than angular measurements because they are based on only 2 landmarks, whereas angular measurements need 3 or 4 landmarks.

However, for the appropriate application of the Pancherz analyses, they should be used with norms from populations similar to the subjects being evaluated. Thus, representative norms for ethnic group, sex, and age are needed. Since most orthodontic intervention is performed when the patient is about 10 to 14 years of age, priority should be given to obtaining norms for this age group. At present, there are no published Chinese or white norms for the Pancherz analyses. The aim of this study was therefore to establish such norms for Chinese and white children.

Material and methods

Two hundred male and 207 female southern Chinese schoolchildren, 12 years old, were selected by a partially stratified random sampling method from 10 schools in Hong Kong. Two girls with previous and current orthodontic treatment were excluded, and the final sample consisted of 200 boys and 205 girls ( Table I ). In addition, a sample was drawn from 2 expatriate schools that agreed to participate in the study, consisting of 47 male and 43 female white schoolchildren, 12 years old, living in Hong Kong, whose parents originated from the United Kingdom. This sample was used for ethnic comparison. Four British boys were excluded from the initial sample because of previous or current orthodontic treatment, so that the final sample consisted of 43 boys and 43 girls. Approval was obtained from the ethical committee, Faculty of Dentistry, University of Hong Kong.

Table I
Demographic data of Chinese and white samples
Age (y)
Range
n Mean SD Median Minimum Maximum
Chinese
Male 200 12.4 0.60 12.5 11.0 13.0
Female 205 12.5 0.38 12.6 11.9 13.0
Difference −0.1 −0.1 −0.9 0.0
White
Male 43 12.4 0.20 12.4 12.1 12.7
Female 43 12.5 0.32 12.3 12.1 13.0
Difference −0.1 0.1 0.0 −0.3

No differences between the samples were statistically significant.

Lateral cephalometric radiographs of all the children were taken in natural head posture as originally defined by Molhave, and later adopted and modified by others. The subjects looked into a mirror 200 cm away after first tilting the head forward and backward with decreasing amplitude until a comfortable position of natural balance was found. The same x-ray machine (GE1000, General Electric, Milwaukee, Wis) was used for both the Chinese and white samples. Magnification was 8.8% for the midsaggital structure. Intensifying screens were used to minimize the exposure level. Free comprehensive dental treatment, including orthodontics, was offered to all subjects, and copies of the original radiographs were later used for diagnosis.

The landmarks and reference lines for Pancherz’s SO and VO analyses are shown in the Figure . Initially, the radiographs were traced manually and then rechecked by digitization and application of a software program (CASSOS 2001, Soft Enable Technology Limited, Hong Kong, PRC). In addition to the actual population reference values for 12-year old children, additional reference values for children aged 10, 11, 13, and 14 years were extrapolated from increments from the analysis of the template obtained from Scandinavian standards.

Fig
A, SO, and B, VO analyses of Pancherz. Landmarks: Ii , incison inferior, the incisal tip of the most prominent mandibular incisor. Is , incison superius, the incisal tip of the most prominent maxillary incisor. Mi , molar inferius, the mesial contact point of the mandibular first permanent molar by a tangent parallel to OLp; when double projection give rise to 2 points, the midpoint is used. Mic , the mesiobuccal cusp tip of the mandibular first molar; when double projection gives rise to 2 points, the midpoint is used. Ms , Molar superius, the mesial contact point of the maxillary first permanent molar by a tangent parallel to OLp; when double projection gives rise to 2 points, the midpoint is used. Msc , the mesiobuccal cusp tip of the maxillary first molar; when double projection gives rise to 2 points, the midpoint is used. Pg , pogonion, the most anterior part of the bony chin determined by a tangent parallel to OLp. A , the deepest point on the anterior contour of the maxillary aleveolar projection determined by a tangent parallel to OLp. N , nasion. S , sella. ANS , anterior nasal spine. PNS , posterior nasal spine. Me , menton. Go , gonion. A, Planes and distances used in SO anlysis: overjet, Is-OLp–Ii-OLp; molar relationship, Ms-OLp–Mi-OLp; maxillary base position, A-OLp; mandibular base position, Pg-OLp; jaw-base relationship, A-OLp–Pg-OLp; maxillary central incisor position, Is-OLp; mandibular central incisor position, Ii-OLp; maxillary central incisor relationship to A-point, Is-OLp–A-OLp; mandibular central incisor relationship to Pg-point, Ii-OLp–Pg-OLp; maxillary first permanent molar position, Ms-OLp; mandibular first permanent molar position, Mi-OLp. B, OLp , occlusal plane perpendicular, reference line perpendicular to OLs through S. Planes and distances used in VO anlysis: overbite, Ii-Ols, the distance Ii perpendicular to OLs; lower face height, ANS-Me; maxillary central incisor position, Is-NL, the distance Is perpendicular to NL; mandibular central incisor position, Ii-ML, the distance Ii perpendicular to ML; maxillary first permanent molar position, Msc-NL, the distance of Msc perpendicular to NL; mandibular first permanent molar position, Mic-ML, the distance of Mic perpendicular to ML; nasal plane angle, NL-NSL, the angle between the maxillary plane (ANS-PNS) and N-S plane; mandibular plane angle, ML-NSL, the angle between the mandibular plane (Me-Go) and N-S plane; maxillary occlusal plane angle, OLs/NSL, the angle between the maxillary occlusal plane and N-S plane; mandibular occlusal plane angle, OLi/NSL, the angle between the mandibular occlusal plane and N-S plane. NL, nasal line (maxillary plane); ML, mandibular line (mandibular plane); NSL, nasal sella line; OLs, maxillary occlusal plane; OLi, mandibular occlusal plane.

Statistical analysis

The t test for independent samples was used, and the levels of statistical significance were P <0.05, P <0.01, and P <0.001. The sex and ethnic differences were also presented as standard deviations. For example, the standard deviation of the sex difference of variable A is

Mean of sex difference(SD of A for boys+SD of A for girls)/2.Mean of sex difference(SD of A for boys+SD of A for girls)/2.
Mean of sex difference ( SD of A for boys + SD of A for girls ) / 2 .

The SD score of the ethnic difference of variable A is

Mean of ethnic difference A(SD of A for Chinese boys+SD of A for white boys)/2.
Mean of ethnic difference A ( SD of A for Chinese boys + SD of A for white boys ) / 2 .

All radiographs were digitized twice with the program CASSOS. The data were averaged and analyzed with SPSS software (version 15, SPSS, Chicago, Ill).

Method errors (ME) were calculated by Dahlberg’s formula, M.E=d22n
M . E = ∑ d 2 2 n
, where d2
∑ d 2
is the sum of the squared differences between the 2 mean values, and n is the number of double measurements. The method errors for linear and angular measurements were not statistically significant and did not exceed 0.5 mm and 0.7°, respectively, for any variable.

Results

With respect to age, there was no statistically significant difference between the sex and ethnic groups ( Table I ). The cephalometric norms of the SO and VO analyses for 12-year old southern Chinese and 12-year old British white children are summarized in Tables II and III , respectively. The ethnic differences for boys and girls are summarized in Table IV . There were large individual variations for all variables for both sex and ethnic groups.

Table II
Cephalometric norms of Pancherz’s SO and VO analyses in Chinese subjects
Boys Girls
Range 95% CI Range 95% CI
Variable Mean SD Median Min Max Lower Upper Mean SD Median Min Max Lower Upper Sex difference SD
Sagittal measurements
Overjet Is-OLp–Ii-OLp 4.3 1.76 4.3 −2.1 10.7 4.0 4.5 3.8 1.49 3.8 −0.1 8.8 3.6 4.0 0.4 0.3
Molar relationship Ms-OLp–Mi-OLp −2.7 1.62 −2.7 −9.8 4.2 −3.0 −2.5 −2.9 1.67 −3.0 −7.5 3.0 −3.2 −2.7 0.2 0.1
Position of maxillary base A-OLp 76.1 3.86 76.1 65.9 88.2 75.6 76.7 74.1 3.95 74.1 64.6 83.8 73.6 74.6 2.0 0.5
Position of mandibular base Pg-OLp 82.3 4.88 82.1 69.4 95.3 81.6 83.0 81.3 5.14 81.7 67.1 95.5 80.6 82.0 1.0 0.2
Jaw relationship A-OLp–Pg-OLp −6.2 3.38 −6.1 −16.3 3.0 −6.6 −5.7 −7.2 3.10 −7.1 −16.6 2.7 −7.6 −6.8 1.0 0.3
Position of maxillary central incisor Is-OLp 88.1 4.54 87.8 76.8 100.6 87.4 88.7 85.9 4.67 85.9 73.8 99.0 85.3 86.6 2.1 0.5
Position of mandibular central incisor Ii-OLp 83.8 4.44 83.6 73.4 94.5 83.2 84.4 82.1 4.61 81.9 70.1 94.7 81.5 82.7 1.7 0.4
Maxillary central incisor relationship to A point Is-OLp–A-OLp 11.9 2.35 11.9 6.2 18.1 11.6 12.3 11.8 2.08 11.8 6.4 17.2 11.6 12.1 0.1 0.0
Mandibular central incisor relationship to Pg Ii-OLp–Pg-OLp 1.5 3.55 1.7 −8.9 11.1 1.0 2.0 0.8 3.43 0.8 −8.0 11.4 0.4 1.3 0.7 0.2
Position of maxillary first permanent molar Ms-OLp 55.0 3.98 54.9 45.4 68.4 54.4 55.5 53.9 4.07 53.7 43.4 65.7 53.3 54.4 1.1 0.3
Position of mandibular first permanent molar Mi-OLp 57.7 4.26 57.7 48.5 69.2 57.1 58.3 56.8 4.50 57.4 46.1 69.1 56.2 57.4 0.9 0.2
Vertical measurements
Overbite Ii-OLs 2.2 1.51 2.4 −1.5 7.7 2.0 2.4 1.8 1.32 1.6 −1.7 7.3 1.6 1.9 0.5 0.3
Lower facial height ANS-Me 64.4 4.36 64.4 55.3 76.1 63.7 65.0 63.1 4.11 63.2 52.5 73.1 62.6 63.7 1.2 0.3
Position of maxillary central incisor Is-NL 28.9 2.72 28.7 21.7 36.05 28.5 29.3 27.7 2.61 27.6 20.65 34.5 27.3 28.1 1.2 0.4
Position of mandibular central incisor Ii-ML 41.3 2.73 41.2 35.2 49.45 40.9 41.7 40.1 2.61 40.0 33.1 46 39.7 40.4 1.2 0.5
Position of maxillary first permanent molar Msc-NL 21.9 2.22 22.0 16.85 27.55 21.5 22.2 21.6 2.02 21.5 16.05 26.85 21.3 21.9 0.3 0.1
Position of mandibular first permanent molar Mic-ML 31.8 2.41 31.4 26 38.5 31.5 32.1 31.4 2.27 31.4 25.65 37.1 31.1 31.7 0.4 0.2
Nasal plane angle NL-NSL 9.1 3.34 9.4 0.25 19.65 8.6 9.6 9.0 3.35 9.4 0.2 17.2 8.5 9.4 0.1 0.0
Mandibular plane angle ML-NSL 35.3 5.57 35.6 18.5 47.15 34.6 36.1 33.6 5.17 34.0 20.5 48.7 32.9 34.3 1.7 0.3
Maxillary occlusal plane angle OLs-NSL 21.6 4.35 22.2 8.7 32.45 21.0 22.2 20.4 4.20 20.9 9.65 33.1 19.8 21.0 1.2 0.3
Mandibular occlusal plane angle OLi-NSL 15.9 4.85 16.4 2.3 29.8 15.2 16.6 15.4 4.84 15.6 1.35 26.65 14.7 16.1 0.5 0.1
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Apr 14, 2017 | Posted by in Orthodontics | Comments Off on Sagittal and vertical occlusal cephalometric analyses of Pancherz: Norms for Chinese children
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