We aimed to compare the standard methods of cephalometry and two-dimensional photogrammetry, to evaluate the reliability and accuracy of both methods.
Twenty-six patients (mean age 25.5, standard deviation (SD) 5.2 years) with Class II relationship and 23 patients with Class III relationship (mean age 26.4, SD 4.7 years) who had undergone bilateral sagittal split ramus osteotomy were selected, with a median follow-up of 8 months between pre- and postsurgical evaluation. Pre- and postsurgical cephalograms and lateral photograms were traced and changes were recorded.
Pre- and postsurgical measurements of hard tissue angles and distances revealed higher correlations with cephalometrically performed soft tissue measurements of facial convexity (Class II: N-PG, r = - 0.50, P = 0.047; Class III: ANB, r = 0.73, P = 0.005; NaPg , r = 0.71, P = 0.007;) and labiomental angle (Class II: SNB, r = 0.72, P = 0.002; ANB, r = - 0.72, P = 0.002; N-B, r = - 0.68, P = 0.004; ANS-Gn, r = 0.71, P = 0.002; Class III: ANS-Gn, r = 0.65, P = 0.043) compared with two-dimensional photogrammetry. However, two-dimensional photogrammetry revealed higher correlation between lower lip length and cephalometrically assessed angular hard tissue changes (Class II: SNB, r = 0.98, P = 0.007; N-B, r = 0.89, P = 0.037; N-Pg, r = 0.90, P = 0.033; Class III: SNB, r = - 0.54, P = 0.060; NAPg, r = - 0.65, P = 0.041; N-Pg, r = 0.58, P = 0.039).
Our findings suggest that cephalometry and two-dimensional photogrammetry offer the possibility to complement one another.
Orthognathic surgery patients have been focusing more and more on postsurgical facial
aesthetic outcomes. Findings in the recent literature suggest that aesthetic
improvement is one of the most relevant motivations besides chewing function for
patients undergoing orthognathic surgery [
Subjects who had undergone single jaw surgery for Class II or Class III relationship were selected from adult treatment records. Exclusion criteria were: patients who revealed an frontal open bite, adiposity (Body Mass Index (BMI) > 30 kg/m2), patients with matured cleft lip and palate, craniofacial syndromes, post-traumatic deformity, and patients who were scheduled to undergo orthognathic surgery without orthodontic treatment or with additional features, e.g. genioplasty or distractor devices. Therefore, orthognathic surgery consisted purely of bilateral sagittal split ramus osteotomy (BSSRO) carried out for mandibular setback or advancement. All subjects had available both a lateral cephalogram and a lateral photogram in the Natural Head Position (NHP) taken pre and postsurgical.
Subjects were positioned in the cephalostat, and then the head holder was adjusted until the ear rods could be positioned into the ears without moving the patient. All radiographs were taken with teeth together in centric occlusion and lips in repose, and with a metric ruler in front of the midfacial vertical line (NHP). No occipital supplement was used. According to the standard of cephalograms, the film distance to the X-ray tube was fixed at 150 cm, and the film distance to the midsagittal plane of the patient's head at 18 cm.
Tracings were done for all cephalograms. After transferring into a PC, the ruler
helped adjust the size of the cephalograms in the software program so that 1 mm on
the rule represented 1 mm of actual scale (life-size) in the Photoshop software
program. The landmarks were identified manually by a single examiner using
photographic software (Adobe Photoshop version 7.0, Adobe Systems, San Jose, CA,
USA). Soft and hard tissue landmarks of the cephalograms were traced using a
modified version [
Hard tissue landmarks and reference lines for tracing of cephalograms: N = Nasion; S = Sella; A = Point A; B = Point B; L1 = Lower incisor; Gn = Gnathion; Pg = Pogonium; ANS = Anterior nasal spine; RF HOR = Horizontal reference line; RF VER = Vertical reference line.
Soft tissue landmarks, angles and distances for tracing cephalograms and photograms: Li = Labrale inferius; Si = Labiomental sulcus; Pg′ = Soft tissue pogonion; 1 = Facial Convexity; 2 = Lower lip length; 3 = Labiomental angle.
Subjects were asked to sit on a chair in front of a pale blue background, maintain a
straight back, and look straight ahead with a relaxed facial expression and eyes
fully open, lips gently closed, and not smiling. A neck holder was then adjusted to
help the subjects fix their position in NHP. For reproducibility, a simple, indirect
light source on the ceiling was used, consisting of four 60-watt fluorescent tubes
to eliminate undesirable shadows from the contours of the facial profile. The
subjects' faces were photographed in right lateral view, together with a metric
scaled ruler in front of the midfacial vertical line (True Vertical [TV]). A
high-resolution digital camera with a flash (Canon 450D, Tokyo, Japan) was firmly
mounted on a photo stand 1 m in front of the subject. All photographs were taken at
2.048 x 1.536 pixels resolution and saved in JPEG file format. Images were stored on
the PC's hard disc drive and then transferred into the photographic software
program. The lateral photographs were adjusted to life-size in accordance to the
adjustment of the cephalograms given above. Soft tissue landmarks, distances and
angles were traced with the tools of the software (
Superimposed lateral photograms to assess pre- and postsurgical soft tissue landmark movements: TV = True Vertical in Nasion; TH = True Horizontal; Trg = Tragus.
The collected data were subjected to statistical analysis using the PASW statistical software package, version 18.0 (SPSS, Chicago, IL, USA). Differences between groups were evaluated using the paired t- test. Results were considered significant if P < 0.05 and highly significant if P < 0.01. Pearson`s correlation analysis was used to assess the degree of correlation between soft and hard tissue changes. Reliability of measurements was determined by randomly selecting 10 cephalograms and 10 lateral photograms to repeat the tracings by a second senior examiner. No significant differences were found when the repeat measurements were evaluated with t-test. The inter-rater correlation (Pearson`s correlation) of data determined by the investigators was 0.94 for cephalometric and 0.95 for photogrammetric tracings. The method error was calculated using the formula:
in which X1 as the first measurement, X2 as the second measurement, and n as the number of repeated records. Significant differences between the reliability of two-dimensional photogrammetry and cephalometry could not been obtained. All respective values of method error calculation for the linear measurements ranged between 0.23 and 0.36 mm for cephalometry and between 0.25 and 0.39 for two-dimensional photogrammetry, for angular measurements between 1.2 and 4.2 degrees and between 1.4 and 3.9 degrees, respectively. Hence, significant differences between the reliability of photogrammetry and cephalometry could not been obtained.
Study sample consisted of 49 white Caucasian subjects. Twenty-six patients with Class II relationship (mean age 25.5; standard deviation [SD] 5.2 years; female n = 16, male n = 10), and 23 patients with Class III relationship (mean age 26.4; SD 4.7 years; female n = 15, male n = 8) were selected with a median follow-up of 8 months (mean 8.3; SD 1.2 months) between pre- and postsurgical evaluation. Significant differences between females and males could not be obtained by cephalometric or two-dimensional photogrammetric measurements, with respect to pre- or postoperative angular or distance measurements, or landmark movements. Therefore, gender was not considered further.
Significant differences between pre- and postsurgical parameters could be found for
all hard tissue measurements exceptional for ANS-Gn in Class III patients (
Differences between pre- and postsurgical parameters for class II and III patients
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II | 75.5 ± 3.8 | 77.7 ± 4.2 | - 2.2 ± 1.8 | < 0.001d | 0.939 |
III | 82.1 ± 5.9 | 79.7 ± 5.3 | 2.3 ± 2.2 | 0.003d | |||
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II | 4.9 ± 3.5 | 2.5 ± 3.3 | 2.4 ± 1.5 | < 0.001d | 0.841 | |
III | - 0.1 ± 2.5 | 2.0 ± 3.3 | - 2.2 ± 1.6 | < 0.001d | |||
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II | - 6.7 ± 8.6 | - 3.1 ± 8.2 | - 3.6 ± 4.5 | 0.006d | 0.898 | |
III | 1.2 ± 6.1 | - 2.6 ± 7.4 | 3.8 ± 3.2 | < 0.001d | |||
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II | 7.7 ± 3.4 | 5.9 ± 4.0 | 1.8 ± 1.7 | < 0.001d | 0.370 | |
III | 1.1 ± 6.3 | 3.6 ± 5.8 | - 2.5 ± 2.8 | 0.007d | |||
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II | 6.6 ± 4.8 | 5.1 ± 5.2 | 1.5 ± 1.6 | 0.002d | 0.124 | |
III | 0.4 ± 7.3 | 3.3 ± 6.8 | - 2.9 ± 3.2 | 0.006d | |||
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II | 36.4 ± 3.4 | 37.1 ± 2.7 | - 1.1 ± 2.1 | 0.044c | 0.467 | |
III | 40.7 ± 4.1 | 40.1 ± 4.8 | 0.6 ± 1.8 | 0.203 | |||
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II | 163.6 ± 6.3 | 167.7 ± 6.4 | - 4.1 ± 4.2 | < 0.001d | 0.818 |
III | 173.9 ± 4.8 | 169.6 ± 6.9 | 4.3 ± 3.5 | < 0.001d | |||
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II | 86.6 ± 28.7 | 109.1 ± 14.4 | - 22.3 ± 22.7 | < 0.001d | 0.051 | |
III | 129.7 ± 11.6 | 124.1 ± 16.7 | 5.6 ± 13.1 | 0.143 | |||
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II | 24.7 ± 2.9 | 25.6 ± 3.1 | - 0.8 ± 2.6 | 0.201 | 0.254 | |
III | 29.2 ± 2.1 | 28.7 ± 2.9 | 0.1 ± 2.1 | 0.388 | |||
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II | 166.5 ± 6.1 | 160.5 ± 4.9 | 5.9 ± 7.1 | 0.002d | 0.614 |
III | 174.8 ± 5.6 | 163.8 ± 5.4 | 10.5 ± 49.5 | 0.003d | |||
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II | 102.2 ± 19.3 | 112.1 ± 15.8 | - 10.1 ± 15.9 | 0.044c | 0.857 | |
III | 129.9 ± 16.2 | 120.6 ± 11.9 | 10.6 ± 19.3 | 0.959 | |||
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II | 24.7 ± 2.9 | 25.6 ± 3.1 | - 0.8 ± 2.6 | 0.201 | 0.933 | |
III | 29.4 ± 2.7 | 28.9 ± 2.3 | 1.7 ± 8.5 | 0.448 |
aP refers to pre- and postsurgical differences (t-test).
bP refers to differences in pre- and postsurgical changes between Class II and III patients (t-test).
cSignificant at the level P < 0.05 (two-tailed).
dSignificant at the level P < 0.01 (two-tailed).
Significant correlations between soft and hard tissue changes for angles and
distances could be found mostly for cephalometric soft tissue measurements of facial
convexity and labiomental angle (
Correlations between soft and harda tissue changes for angles and distances in Class II and Class III patients
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II | r | 0.45 | 0.63 | - 0.06 | - 0.28 | - 0.50 | 0.32 |
P | 0.083 | 0.035b | 0.825 | 0.298 | 0.047b | 0.224 | |||
III | r | - 0.31 | 0.73 | 0.71 | - 0.27 | - 0.19 | - 0.38 | ||
P | 0.302 | 0.005c | 0.007c | 0.370 | 0.525 | 0.203 | |||
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II | r | 0.72 | - 0.72 | - 0.24 | - 0.68 | - 0.48 | 0.71 | |
P | 0.002c | 0.002c | 0.377 | 0.004c | 0.058 | 0,002c | |||
III | r | - 0.38 | 0.06 | - 0.12 | 0.42 | 0.49 | 0.65 | ||
P | 0.200 | 0.851 | 0.696 | 0.151 | 0.083 | 0.043b | |||
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II | r | 0.51 | - 0.35 | - 0.04 | - 0.48 | - 0.33 | 0.49 | |
P | 0.041b | 0.181 | 0.881 | 0.058 | 0,209 | 0.055 | |||
III | r | 0.05 | 0.10 | - 0.10 | 0.01 | 0.03 | 0.59 | ||
P | 0.871 | 0.746 | 0.735 | 0.966 | 0.930 | 0.032b | |||
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II | r | 0.11 | -0.11 | 0.25 | - 0.13 | - 0.13 | 0.08 |
P | 0.680 | 0.693 | 0.354 | 0.627 | 0.633 | 0.762 | |||
III | r | - 0.09 | 0.15 | - 0.30 | -0.05 | - 0.04 | 0.33 | ||
P | 0.773 | 0.633 | 0.321 | 0.877 | 0.891 | 0.269 | |||
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II | r | 0.11 | -0.23 | - 0.24 | - 0.17 | - 0.15 | 0.25 | |
P | 0.685 | 0.396 | 0.366 | 0.539 | 0.576 | 0.357 | |||
III | r | 0.33 | - 0.56 | 0.52 | - 0.26 | - 0.25 | - 0.26 | ||
P | 0.264 | 0.048b | 0.068 | 0.389 | 0.420 | 0.398 | |||
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II | r | 0.98 | - 0.09 | 0.13 | 0.89 | 0.90 | - 0.11 | |
P | 0.007c | 0.729 | 0.634 | 0.037b | 0.033b | 0.673 | |||
III | r | - 0.54 | 0.25 | - 0.65 | 0.49 | 0.58 | 0.13 | ||
P | 0.060 | 0.405 | 0.041b | 0.089 | 0.039b | 0.667 |
aAll hard tissue parameters were assessed by cephalometry.
bSignificant at the level P < 0.05 (two-tailed).
cSignificant at the level P < 0.01 (two-tailed).
dr = Pearson`s correlation; P = significance.
Significant differences between two-dimensional photogrammetric and cephalometric
assessment of soft tissue landmark movements in Class II and III patients could be
obtained neither in horizontal nor in vertical direction (
Comparison between pre- and postsurgical soft tissue landmark movements assessed by two-dimensional photogrammetry and cephalometry in Class II and III patients
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Li | II | 2.1 ± 1.2 | 2.6 ± 1.6 | 0.537a |
III | - 3.2 ± 1.6 | - 4.6 ± 1.9 | 0.255a | ||
Si | II | 2.8 ± 1.4 | 4.6 ± 1.1 | 0.065a | |
III | - 4.4 ± 0.8 | - 4. ± 2.3 | 0.862a | ||
Pg` | II | 2.8 ± 1.1 | 4.1 ± 1.8 | 0.258a | |
III | - 4.2 ± 1.7 | - 3.8 ± 2.9 | 0.803a | ||
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Li | II | 0.2 ± 0.8 | 0.4 ± 1.3 | 0.785a |
III | 1.4 ± 1.5 | 1.8 ± 0.8 | 0.623a | ||
Si | II | - 0.8 ± 0.8 | - 1.6 ± 0.5 | 0.117a | |
III | 2.4 ± 1.1 | 3.4 ± 2.8 | 0.491a | ||
Pg` | II | - 0.2 ± 1.6 | - 1.2 ± 2.2 | 0.435a | |
III | 2.2 ± 1.3 | 3.4 ± 1.9 | 0.291a |
aNo statistically significant difference (t-test).
The results of this study supported the findings in other studies in that mandibular
movements with BSSRO were effective on soft tissues both in vertical and horizontal
directions [
Findings in this study suggest that cephalometry and two-dimensional photogrammetry
offer the possibility to complement one another. Pre- and postsurgical measurements
of hard tissue angles and distances revealed higher correlations with
cephalometrically performed soft tissue measurements of facial convexity and
labiomental angle than did two-dimensional photogrammetry. However, although higher
correlations between hard and soft tissue cephalometry should be naturally explained
by the fact that tracings for hard and soft tissue are performed on the same
cephalogram, two-dimensional photogrammetry revealed higher correlations between the
lower lip length and cephalometrically assessed angular hard tissue changes. In
comparison, Marşan et al. [
This study showed cephalometrically and photogram metrically no differences between
females and males. Fernández-Riveiro et al. [
In recent studies computer-aided three-dimensional digitizers have been used to
evaluate facial changes. These studies have suggested that measurements obtained by
new technological equipment should be more reliable than the conventional
cephalometry, especially with respect to tracings of cranial-base landmarks [
For bilateral sagittal split ramus osteotomy cases, cephalometry and two-dimensional photogrammetry are still practical and reliable tools offer the possibility to complement one another.
The authors report no conflicts of interest related to this study. The authors would like to thank Ilknur Tetik (B.A., School of Architecture, Bremen, Germany) for giving us technical support realizing two-dimensional photogrammetry.