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.
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.
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.
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.
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.
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 .
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 .
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.
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.
|Range||95% CI||Range||95% CI|
|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|
|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|