Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
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Soft tissue response and facial symmetry after orthognathic surgery Kai Wermker a, *, Johannes Kleinheinz b, Susanne Jung b, Dieter Dirksen c a
Fachklinik Hornheide, Department of Cranio-Maxillofacial Surgery, Dorbaumstrasse 300, 48157 Muenster, Germany University Hospital Münster, Department of Cranio-Maxillofacial Surgery, Waldeyerstraße 30, 48149 Muenster, Germany c University Hospital Münster, Department of Prosthetic Dentistry and Biomaterials, Waldeyerstraße 30, 48149 Muenster, Germany b
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 28 August 2013 Accepted 6 January 2014
Objective: In orthognathic surgery aesthetic issues and facial symmetry are vital parameters in surgical planning. Aim of this investigation was to document and analyze the results of orthognathic surgery on the base of a three-dimensional photogrammetric assessment, to assess the soft tissue response related to the skeletal shift and the alterations in facial symmetry after orthognathic surgery. Patients and methods: In this prospective clinical trial from January 2010 to June 2011, 104 patients were examined who underwent orthognathic surgery due to mono- or bimaxillary dysgnathia. The standardized measurements, based on optical 3D face scans, took place one day before orthognathic surgery (T1) and one day before removal of osteosynthesis material (T2). Results: Soft tissue changes after procedures involving the mandible showed significant positive correlations and strong soft tissue response (p < 0.05). The midfacial soft tissue response after maxillary advancement was only of minor extent (p > 0.05). The facial surfaces became more symmetric and harmonic with the exception of surgical maxillary expansion, but improvement of facial symmetry revealed no statistical significance. Conclusion: Soft tissue response after orthognathic surgery and symmetry are only partially predictable, especially in the maxillary and midfacial region. Computer programs predicting soft tissue changes are not currently safely reliable and should not be used or with caution to demonstrate a patient potential outcome of surgery. Ó 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Keywords: Symmetry Orthognathic surgery Soft tissue changes Three-dimensional Face scan Profile
1. Introduction In the planning of skeletal orthognathic correction, aesthetics and matters of attractiveness are of vital importance to the patients. A retrospective analysis of 299 patients at the University Hospital Muenster showed that for 49.5% of the women and for 34.7% of the male patients aesthetics and looks were one of the determinative reasons for surgical intervention (Wesseling, 2004). To allow for optimal functional and visual results the surgical planning should be based on reliable prognostic methods (AboulHosn Centenero and Hernández-Alfaro, 2012; Donatsky et al., 2009; Falter et al., 2012). So far the diagnosis and surgical
* Corresponding author. Fachklinik Hornheide at the Westfalian Wilhelms University Muenster, Department of Cranio-Maxillofacial Surgery, Head and Neck Surgery, Dorbaumstrasse 300, 48157 Muenster, Germany. Tel.: þ49 251 3287 421; fax: þ49 251 3287 424. E-mail addresses: [email protected], [email protected] (K. Wermker).
preparation are based on techniques that come with restrictions in terms of detailed imaging and depth of focus. In general they are associated with radiologic diagnostics and radiation exposure (Kim et al., 2013; Park et al., 2013, 2012; Yáñez-Vico et al., 2011). The current three-dimensional measurement systems have not gained acceptance for routine use yet due to either enormous technical charges or a high radiation. The aim of this investigation was to enhance the prognostic predictability of the outcomes of orthognathic surgery. The analysis of the soft tissue response to skeletal movement was the underlying technique. A three-dimensional optical measurement system was applied, that is based on the fringe projection technique and does not depend on an X-ray technique. In general symmetry is assessed by portrait photography, symmetrical deviations in all three dimensions can thus be not analyzed. Another tool used to analyze symmetry and to make a prognosis of soft tissue response of patients’ faces is based on a laser technique (Shimomatsu et al., 2012). Holberg et al. compared laser-
1010-5182/$ e see front matter Ó 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jcms.2014.01.032
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
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K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
based profile predictions to an established 2D-technique relying on cephalometric data. Whereas laser-based prognosis came with a mean variation of 0.32 mm regarding the horizontal plane the 2D prediction showed a mean deviation of 0.75 mm and thus was clearly inferior (Holberg et al., 2005). Comparable investigations underlined the fact that a calculation of soft tissue response is extremely difficult and highly unreliable. Joss et al. see the problems in poor study designs and a lack of standardized measurement techniques. Another crucial point is the enormous individual variability of the soft tissue response depending on different morphology, thickness and elasticity of the tissues (Joss et al., 2010). In this study a three-dimensional symmetry index (3D-SI) was established to objectively compare facial symmetry before and after orthognathic surgery. The relevant questions were: Is there a significant correlation between sagittal soft tissue response and skeletal movement based on the orthognathic planning? Is orthognathic surgery able to increase and improve facial symmetry?
2. Material and methods 2.1. Patients and investigations For this prospective study orthognathic patients with planned surgical correction of dysgnathia over a one and a half year period (from January 2010 to June 2011) were recruited consecutively, including all forms of dysgnathia and operative procedures. Exclusion criteria were age below 18 years, unwillingness to participate in the study and those with orthognathic operations prior to the newly planned procedure. All patients gave their informed written consent for participating in this study and the study was performed in accordance with the guidelines for good clinical practise (GCP). In addition to general health status and characteristics of the dysgnathia, the planned translocation was assessed with The University of Muenster model surgery system for orthognathic surgery (KD-MMS)”, as described below. One day before operation a preoperative face scan was performed and the preoperative threedimensional (a-)symmetry index (3D-SI) was calculated (see description below). Postoperative assessment by face scan took place one day before removal of osteosynthesis material to prevent confounding due to swelling, and the postoperative 3D-SI was calculated. For 12 distinct facial points, change (distance in mm) was measured between pre- and postoperative face scan. All these procedures are described in more detail in the following section of the paper. 2.2. Assessment of dental and skeletal jaw movement The distance of movement of the jaws through the orthognathic procedure was planned according to KD-MMS (Ehmer et al., 2013; Wiechmann et al., 1997). With the use of plaster casts, exact threedimensional positioning of maxilla and/or mandible was planned preoperatively and formed the basis for the splints used intraoperatively. Philosophy and procedures of this system were previously described in detail (Ehmer et al., 2012). As a result of the KD-MMS tool, exact planned movement of distinct points of the upper and lower dental arch and jaw can be measured. For the purposes of this study, only the sagittal changes of the following 5 points in each jaw (10 points in total) were considered for further analysis: right first molar, right cuspid, centre (midline, between incisors), left cuspid and left first molar.
Negative distances mean a setback procedure, positive values represent forward movements/advancement. 2.3. 3D scanning system The 3D scanning system is based on the fringe projection technique and has been developed at the Department of Prosthetic Dentistry and Biomaterials at the Westfalian Wilhelms University of Muenster and its technique and principles were described previously in detail (Bischoff et al., 2007; Dirksen et al., 2002; Westhäuser et al., 2008). The system enables a three-dimensional face scan with accurate skin colour assessment (true colour rgb model) using only normal visible light without any type of ionizing radiation. Over 1.5 s 200,000 to 800,000 3D-points can be assessed. Measurement accuracy of these 3D-coordinates is approximately 0.6 mm in X-axis and 0.2 mm in Y-axis within a field of 600 mm 450 mm. 2.4. Calculation of the 3D-symmetry index (3D-SI) For objective assessment and measurement of asymmetry, a special three-dimensional Symmetry Index (3D-SI) was calculated on the basis of the optically acquired data as follows: The procedure is based on the proposals of a research group at the University of Erlangen (Hartmann et al., 2007; Nkenke et al., 2006). First the original 3D-dataset (“original cloud”) is mirrored automatically at the medianesagittal plane to generate a “mirrored cloud”. Afterwards, the original and mirrored cloud are matched. Registration is performed automatically by the software, using an iterated-closest-point-algorithm that matches both clouds with the lowest achievable distance from each other. The 3D-SI is calculated from the mean of all distances between original and mirrored cloud (a) and the cross-section dimension of the face (d) to overcome differences between smaller and greater faces, using the following formula: 3D-SI [ (a/d) 3 1000. In a perfectly symmetric face, the 3D-SI would be 0. The greater the value of the 3D-SI is, the more asymmetric is the face. This easy to calculate symmetry index therefore enables an objective assessment of facial symmetry. In previous studies we proved a good correlation of the 3D-SI with perceptually judged symmetry and attractiveness (Krückemeier, 2013). For visualization of asymmetries, a false-colour image can be generated, showing the asymmetric regions of the face in warmer colours (yellow and red, see Fig. 1). 2.5. Measurement of profile changes To assess profile changes of the facial soft tissue after the orthognathic operation, pre- and postoperative face scan clouds were also matched to each other. A rough overlap was made manually by marking 7 corresponding points (medial and lateral canthus of both eyes, nasal tip and left and right angle of mouth). For fine adjustment, areas assumed not to be affected by the operation (orbita and eyes, brows and forehead) were matched to each other for minimal distance between each other by a computed iterative algorithm. Different section planes were generated: 3 vertical section planes perpendicular to the bipupillary plane (through the left pupil, through the mediane sagittal plane in the half of the bipupillary distance and through the right pupil) and 4 horizontal planes parallel to the bipupillary plane (and therefore perpendicular to the vertical planes) through the mediansagittal points Subnasale (SN, junction between nasal columella and upper lip), Upper Lip (UL, most anterior point of the upper lip), Lower Lip (LL, most anterior point of the lower lip) and Pogonion molle (PM, most anterior point of
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
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Fig. 1. Example of visualization of asymmetric parts of the face (three-dimensional cloud with false colour overlay, scale in mm) showing pre- and postoperative situations in comparison. Symmetry improved from a preoperative 3D-SI of 3.87 (left) to a more favourable 3D-SI of 2.82 (right).
the chin) were generated. As a result in each cloud (pre- and postoperative face scan) at the cut-points of vertical and horizontal planes the 12 landmarks were created (for each above mentioned point two paramedian ones (right and left side) and one mediansagittal point). Fig. 2 illustrates the scheme of preand postoperative profile lines and their sections/cut-points. The distance between the corresponding pre- and postoperative points was measured in millimetre in sagittal direction (again, negative distances mean a setback procedure, positive values represent forward movements/advancement).
2.6. Statistical analysis To assess significance of differences between different groups of patients (e.g. according to gender, type of dysgnathia or performed operative technique), Chi-square test and Fisher’s exact test were applied for categorical variables, for metric parameters Kruskale Wallis-H test was used as non-parametric test for not normally distributed data and analysis of variance (ANOVA) with post hoc Tamhane T2 test was used for normally distributed variables. Comparison of pre- and postoperative metric variables was done with the Wilcoxon matched pairs test for non-normally distributed data, in normally distributed variables t-test for joined variables was used. Analysis of correlations between jaw translocation (planned distance according to KD-MMS procedure at the different dental regions as described above) and distances between the pre- and postoperative three-dimensional face scan for above described landmarks were tested on significance using Spearman’s correlation analysis. All statistical analyses were performed by a statistician using the Statistical Package for Social Sciences (SPSS), version 16.0 for WindowsÒ (SPSS Inc., Chicago, Illinois, USA). 3. Results 3.1. Study population
Fig. 2. Scheme of pre- (blue) and postoperative (green) profile lines and their sections/ cut-points.
In total 104 patients (62 females, 42 males) with a mean age of 26.6 years (SD 8.4 years) were included into the study. 50 patients suffered from mandibular retrognathia, 42 had a prognathic mandible and in 12 patients the lower jaw had a correct skeletal position. In the upper jaw, 48 patients showed maxillary retrognathia, 1 patient had a maxillary prognathia, 10 patients suffered from transversal hypoplasia of the maxilla and in 45 patients we found no skeletal dysgnathia of the upper jaw. 41 patients received an isolated operation of the lower jaw (bilateral sagittal split ramus osteotomy according to Obwegeser-DalPont, BSSRO), in 5 patients only the maxilla was translocated (LeFort-I osteotomy), in 48 patients a bimaxillary orthognathic procedure (BSSRO þ LeFort-I osteotomy, BIMAX) was performed and 10 patients received surgically assisted rapid maxillary expansion by transpalatinal distraction (SARME/TPD after subtotal LeFort-I osteotomy). The main groups of sagittal movement were maxillary advancement (n ¼ 51, mean distance ¼ 3.62 mm), mandibular advancement (n ¼ 58, mean distance ¼ 5.18 mm) and
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
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K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
Table 1 According to the KD-MMS procedure planned dental and skeletal movement (explanation see text). Planned movement ad distinct dental points RFM
RC
Maxillary advancement (n [ 51) Mean [mm] 3.46 3.51 SD [mm] 2.07 2.00 Max [mm] 7.50 7.50 Mandibular advancement (n [ 58) Mean [mm] 5.33 5.40 SD [mm] 2.93 2.78 Max [mm] 13.0 13.0 Mandibular Setback (n [ 32) Mean [mm] 4.19 4.27 SD [mm] 3.35 3.27 Max [mm] 13.5 15.0
Center
LC
LFM
3.43 1.51 7.00
3.88 1.79 7.50
3.81 1.74 7.50
5.02 2.60 11.0
5.22 3.22 15.0
4.93 3.35 14.0
3.59 2.94 8.5
2.72 3.66 10.5
2.77 3.43 11.5
SD ¼ standard deviation; Max ¼ maximum movement. RFM ¼ right first molar; RC ¼ right cuspid. LFM ¼ left first molar; LC ¼ left cuspid.
mandibular setback (n ¼ 32, mean distance ¼ 3.51 mm). Detailed planned movements for the above described distinct points in the upper and lower jaw are presented in Table 1. 3.2. Profile changes The measured profile changes for the 12 facial points (SN, UL, LL and PM on the right and left side and in the median) in maxillary advancement, mandibular advancement and mandibular setback operations are shown in detail in Table 2. Profile changes represented the underlying skeletal movement and were not uniform at all assessed facial points. For maxillary advancement, largest anterior change (2.02 mm) was measured at the right SN point. For mandibular advancement, the right PM point showed the largest movement (2.78 mm). In mandibular setback cases the greatest movement was measured at left PM (5.38 mm). Results of correlation analysis showed nearly no significant (p > 0.05) and also very weak correlations (rs < 0.3) between preoperatively planned upper jaw movement and changes in soft tissue points SN and UL. A significant (p < 0.05) correlation of rs ¼ 0.311 could only be found between planned advancement of the upper first molar of the right side and the point SN median. Concerning mandibular movements, the correlations between preoperatively planned distance and soft tissue changes at the points LL and PM were all significant (p < 0.05, for some items even p < 0.01) and also stronger with correlation coefficients rs reaching from 0.333 to 0.570 (Table 3). In summary, the soft tissue changes of the upper lip and subnasale (UL, SN) only slightly followed the planned dental and skeletal movement of the maxilla between 3% and 34 % without clear and statistically significant correlations. Soft tissue changes of the lower third part of the face (points LL and PM) are much more strongly correlated with the underlying planned mandibular movement. The extent of soft tissue changes lay between 52% and a maximum of up to 130% (at the point PM) of the planned lower jaw translocation. The region of the Pogonion (PM points, especially PM median) showed best correlations and highest extent of hard tissue follow. 3.3. Symmetry analysis Considering the whole study population of 104 participants, symmetry improved, but this did not reach statistical significance better than on a 10% level (p ¼ 0.072). Mean preoperative 3D-SI was 3.58 (SD ¼ 1.52), mean postoperative 3D-SI was 3.34 (SD ¼ 1.05), so
the mean improvement was 0.24 (SD ¼ 0.98, 95% confidence interval 0.023 to 0.506). Comparing pre- and postoperative symmetry measurements differentiated according to different operation procedures (Table 4) asymmetry increased only after SARME/TPD. After BSSRO, LeFort-I osteotomy and BIMAX procedures symmetry improved, but without being statistically significant (p > 0.05). Fig. 3 illustrates the pre- and postoperative 3DSI for BSSRO alone, BIMAX and SARME/TPD groups. 4. Discussion In this investigation 104 patients were analyzed. Compared to similar trials dealing with hard and soft tissue alterations after
Table 2 Sagittal soft tissue changes at different facial points after different types of sagittal jaw translocations. Soft tissue change at facial point
Skeletal jaw translocation Maxillary advancement
Mandibular advancement
Mandibular setback
n
51
58
32
SN right Mean [mm] SD [mm] Max [mm] SN median Mean [mm] SD [mm] Max [mm] SN left Mean [mm] SD [mm] Max [mm] UL right Mean [mm] SD [mm] Max [mm] UL median Mean [mm] SD [mm] Max [mm] UL left Mean [mm] SD [mm] Max [mm] LL right Mean [mm] SD [mm] Max [mm] LL median Mean [mm] SD [mm] Max [mm] LL left Mean [mm] SD [mm] Max [mm] PM right Mean [mm] SD [mm] Max [mm] PM median Mean [mm] SD [mm] Max [mm] PM left Mean [mm] SD [mm] Max [mm]
2.02 2.10 5.7
1.69 2.21 4.2
1.30 3.48 2.9
0.07 1.48 2.4
0.08 1.44 2.6
0.03 1.05 1.5
1.24 1.37 3.5
1.37 1.41 2.7
0.35 2.62 2.4
1.23 2.05 4.5
1.67 1.70 3.4
0.18 3.63 3.5
0.81 1.89 4.0
1.25 2.04 3.1
0.06 1.84 2.8
1.15 2.10 7.8
2.42 3.41 3.5
1.50 3.49 2.6
0.31 3.49 5.9
1.08 2.23 8.3
2.27 4.08 9.2
1.12 5.24 8.6
1.35 3.90 7.2
3.15 5.52 10.3
0.67 3.89 5.9
1.10 3.95 8.3
2.60 3.96 9.0
0.85 6.68 6.1
2.78 3.14 9.7
3.85 9.14 20.3
0.89 4.39 5.8
1.27 3.70 10.3
2.62 4.28 9.2
1.33 6.07 7.9
1.97 6.22 12.3
5.38 5.48 13.8
SD ¼ standard deviation; Max ¼ maximum movement. SN ¼ Subnasale; UL ¼ upper lip. LL ¼ lower lip; PM ¼ Pogonion molle.
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7 Table 3 Results of correlation analysis (Spearman correlation coefficient rs) between soft tissue changes of the lower third part of the face in orthognathic operations of the mandibula. Soft tissue change
Planned movement ad distinct dental points RFM
RC
Center
LC
LFM
LL right LL median LL left PM right PM median PM left
0.385** 0.382** 0.464** 0.495* 0.500** 0.532**
0.390** 0.377** 0.500** 0.563** 0.540** 0.574**
0.375** 0.362** 0.540** 0.572** 0.527** 0.544**
0.403** 0.333** 0.529** 0.543** 0.528** 0.449**
0.375** 0.349** 0.535** 0.543** 0.518** 0.427*
Significance: *p < 0.05; **p < 0.01. SN ¼ Subnasale; UL ¼ upper lip. LL ¼ lower lip; PM ¼ Pogonion molle. RFM ¼ right first molar; RC ¼ right cuspid. LFM ¼ left first molar; LC ¼ left cuspid.
orthognathic surgery this number provides a sound base for the deduction of conclusive results referring to different kinds of orthognathic surgery and the respective diagnosis. Whereas Björk et al. included 32 patients in their analysis, Naoumova et al. assessed 42 probands and Chew et al. a group of 30 persons (Björk et al., 1971; Chew et al., 2008; Freihofer, 1976; Naoumova et al., 2008). Drescher et al. and Noell et al. dealt with groups of 136 and 165 patients (Drescher et al., 1990; Noell, 1999). The size of the study group containing over hundred patients provides a solid data basis for convincing results especially as different surgical procedures are compared. In the aforementioned investigations the assessment of the soft tissues and profile relies on different skeletal landmarks presented in the lateral cephalogram. The chosen references vary strongly between the different trials, so a standardized procedure with an analogous technique cannot be indentified (Björk et al., 1971; Chew et al., 2008; Dolce et al., 2003; Drescher et al., 1990; Freihofer, 1976; Naoumova et al., 2008; Noell, 1999). In contrast to the majority of studies dealing with similar issues, the data in this trial results from dental reference points and a three-dimensional, investigator-independent photogrammetric study. One key-advantage of this kind of measurement lies in the additional information retrieved from the analysis of the paramedian plane in addition to the median plane. Considering the relevance of the prominence of the zygomatic arch in evaluating facial symmetry, the information on this paranasal area is of crucial importance. Table 4 Comparison of pre- and postoperative three-dimensional symmetry index (3D-SI) for different surgical procedures. OP-Procedures
3D-Symmetry index (3D-SI)
Sign.
Pre-OP
Post-OP
(p-value)
2.99 0.91
(0.550)
2.94 0.84
(0.655)
3.56 1.17
(0.131)
3.57 0.90
(0.378)
Only BSSRO (n [ 41) Mean 3.05 SD 0.90 Only LeFort-I osteotomy (n [ 5) Mean 3.08 SD 1.09 BIMAX (n [ 48) Mean 3.99 SD 1.81 SARME/TPD (n [ 10) Mean 3.43 SD 1.13
5
Current literature underlines the fact that stereophotogrammetry represents an easily applicable, quick, noninvasive and precise technique of facial surface scanning. With a record time of 1.5 s the resolution capacity ranges between 0.2 mm and 0.6 mm. Other publications that emphasized the advantages of 3D photogrammetry have come from Hoefert et al., Wong et al. and de Menezes et al.: they too described the technique as reliable, reproducible and a radiation-free tool for orthodontic diagnostics (de Menezes et al., 2010; Hoefert et al., 2010; Wong et al., 2008). This combination of quick precision, tolerance and additional information qualifies the photogrammetric technique as a helpful analytic tool in orthognathic diagnosis, treatment planning and surgical follow-up. One outstanding result in this data is the fairly moderate soft tissue response of the midface after maxillary movement even if skeletal maxillary and mandibular shifts follow similar distances. A possible explanation might lie in the characteristic surgical procedure, when a part of the anterior nasal spine is reduced to harmonize the bony profile, especially when the maxilla moves forward. So the maxillary skeletal shift is indirectly reduced, resulting in a minor soft tissue response. Another reason for the exceptionally low levels of soft tissue response after maxillary correction may be seen in the applied matching procedure. The eye and nose area are defined as constant regions, where the pre- and postoperative data clouds are matched congruently. Due to this specialty of the applied technique the changes of the near midfacial soft tissues might become not as prominent as the soft tissue response in the more distant mandibular regions. Generally the midface soft tissues respond less perceptibly to skeletal alterations. The improvement of facial aesthetics including the correction of asymmetric features is often one of the reasons why patients seek to surgical intervention. This study underlines the fact that orthognathic surgery results in more facial symmetry as is documented in current literature. The relevance of symmetry for a more pronounced attractiveness is controversially discussed (Borelli and Berneburg, 2010). Braun et al. concluded that symmetry alone does not automatically define beauty but asymmetry on the other hand makes a face less attractive (Braun et al., 2001). Patients suffering from malocclusion often show less symmetric features (Sforza et al., 2007). A statistically significant increase of symmetry by surgical correction as described in the literature was not confirmed by the data analyzed (Ferrario et al., 1999; Hajeer et al., 2004; Ko et al., 2009), though a general tendency to more symmetric faces after orthognathic surgery was revealed especially regarding the lower facial third. Whereas stereophotogrammetry is a dependable method for analysis facial soft tissues, the photogrammetric technique so far does not provide the technical base for a reliable morphologic prediction of soft tissue reaction to the skeletal shift to present the probable outcome. In agreement with other researchers, we conclude from our results that using radiation free optical surfaces data and three-dimensional software based analysis (e.g. of symmetry) provides a fast, detailed and physically undemanding tool of measurement (Choi et al., 2013; Stauber et al., 2008). Stereophotogrammetry therefore serves as an apt addition to orthognathic diagnostics with the special advantage of three-dimensional imaging in contrast to X-ray diagnostic or photography. 5. Conclusion
SD ¼ standard deviation. BSSRO ¼ bilateral sagittal split ramus osteotomy (only mandibula). BIMAX ¼ bimaxillary procedure (BSSRO þ LeFort-I osteotomy). SARME/TPD ¼ surgically assisted rapid maxillary expansion/transpalatinal distraction.
With the exception of surgically assisted rapid maxillary expansion and transpalatinal distraction (SARME/TPD), mono- or bignathic orthognathic surgery can be expected to improve facial symmetry. The soft tissue response after orthognathic surgery and the amount of symmetry changes are only partially predictable,
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
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K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
Fig. 3. Boxplots of pre- and postoperative measured three-dimensional symmetry index (3D-SI) in different groups of orthognathic surgery (explanations see text).
especially in the maxillary and midfacial region. Whereas the lower face and mandibular region showed high, and therefore more predictable, correlations between hard and soft tissue changes, correlations are weak in the maxilla and midface. Computer programs predicting soft tissue changes are not currently reliable and should not be used, or should be used with caution, to demonstrate to a patient the potential outcome of surgery. Authors contributions KW developed the conception and design of the study, helped to analyze the data and drafted the manuscript. SJ performed data analysis, performed data interpretation, and helped to draft the manuscript. JK revised the article critically, gave important intellectual content and gave final approval to the manuscript. DD developed the optical scanning system, made substantial intellectual contributions and helped in conception of the study. Sponsorship There was no financial or material support for this study by any company. Role of funding sources None. Conflict of interest There were no financial and personal relationships with other people or organizations that could inappropriately influence (bias) our work. All authors declare that there is no conflict of interest. Acknowledgements We thank Anna Sehrbrock for helping in data acquisition and performing the optical face scan. References Aboul-Hosn Centenero S, Hernández-Alfaro F: 3D planning in orthognathic surgery: CAD/CAM surgical splints and prediction of the soft and hard tissues results e our experience in 16 cases. J Craniomaxillofac Surg 40: 162e168, 2012 Bischoff G, Böröcz Z, Proll C, Kleinheinz J, von Bally G, Dirksen D: Modular optical topometric sensor for 3D acquisition of human body surfaces and long-term monitoring of variations. Biomed Tech (Berl) 52: 284e289, 2007
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K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7 therapy-induced changes in facial soft tissue: a pilot study. J Orofac Orthop 71: 221e234, 2010 Holberg C, Heine AK, Geis P, Schwenzer K, Rudzki-Janson I: Three-dimensional soft tissue prediction using finite elements. Part II: clinical application. J Orofac Orthop 66: 122e134, 2005 Joss CU, Joss-Vassalli IM, Kiliaridis S, Kuijpers-Jagtman AM: Soft tissue profile changes after bilateral sagittal split osteotomy for mandibular advancement: a systematic review. J Oral Maxillofac Surg 68: 1260e1269, 2010 Kim DS, Huh KH, Lee SS, Heo MS, Choi SC, Hwang SJ, et al: The relationship between the changes in three-dimensional facial morphology and mandibular movement after orthognathic surgery. J Craniomaxillofac Surg 2. http://dx.doi.org/ 10.1016/j.jcms.2013.01.011, 2013 Mar pii: S1010-5182(13)00012-7, [Epub ahead of print], 2013 Ko EWC, Huang CS, Chen YR: Characteristics and corrective outcome of face asymmetry by orthognathic surgery. J Oral Maxillofac Surg 67: 2201e2209, 2009 Krückemeier K: Evaluation einer Methode zur quantitativen Erfassung dreidimensionaler Gesichtsasymmetrien, http://miami.uni-muenster.de/servlets/ SearchServlet?H_lastPage¼results&H_anfZeile¼0, [WWW Document]. URL Naoumova J, Söderfeldt B, Lindman R: Soft tissue profile changes after vertical ramus osteotomy. Eur J Orthod 30: 359e365, 2008 Nkenke E, Lehner B, Kramer M, Haeusler G, Benz S, Schuster M, et al: Determination of facial symmetry in unilateral cleft lip and palate patients from threedimensional data: technical report and assessment of measurement errors. Cleft Palate-Craniofacial J 43: 129e137, 2006 Noell H: Profilveränderungen nach chirurgischer Therapie skelettaler Dysgnathien: Weichteilfolgeverhalten und Einfluß der Gewebsdicke/Hennecke Noell; 1999, Schuüling, Münster Park JY, Kim MJ, Hwang SJ: Soft tissue profile changes after setback genioplasty in orthognathic surgery patients. J Craniomaxillofac Surg 7. http://dx.doi.org/ 10.1016/j.jcms.2013.01.005, 2013 Feb pii: S1010-5182(13)00006-1, [Epub ahead of print], 2013
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Park SB, Yoon JK, Kim YI, Hwang DS, Cho BH, Son WS: The evaluation of the nasal morphologic changes after bimaxillary surgery in skeletal class III malocclusion by using the superimposition of cone-beam computed tomography (CBCT) volumes. J Craniomaxillofac Surg 40: e87e92, 2012 Sforza C, Peretta R, Grandi G, Ferronato G, Ferrario VF: Three-dimensional facial morphometry in skeletal Class III patients. A non-invasive study of soft-tissue changes before and after orthognathic surgery. Br J Oral Maxillofac Surg 45: 138e144, 2007 Shimomatsu K, Nozoe E, Ishihata K, Okawachi T, Nakamura N: Three-dimensional analyses of facial soft tissue configuration of Japanese females with jaw deformity e a trial of polygonal view of facial soft tissue deformity in orthognathic patients. J Craniomaxillofac Surg 40: 559e567, 2012 Stauber I, Vairaktaris E, Holst A, Schuster M, Hirschfelder U, Neukam FW, et al: Three-dimensional analysis of facial symmetry in cleft lip and palate patients using optical surface data. J Orofac Orthop 69: 268e282, 2008 Wesseling A: Subjektive Bewertung einer kieferorthopädisch-kieferchirurgischen Kombinationstherapie, http://nbn-resolving.de/urn:nbn:de:hbz:699609391096, [WWW Document], URL Westhäuser M, Bischoff G, Böröcz Z, Kleinheinz J, von Bally G, Dirksen D: Optimizing color reproduction of a topometric measurement system for medical applications. Med Eng Phys 30: 1065e1070, 2008 Wiechmann D, Ehmer U, Joos U, Dörr-Neudeck K: A prefabricated, calibrated double-base procedureeKDMMS. For the simulation and 3-dimensional planning using an articulator in orthognathic surgery. Rev Stomatol Chir Maxillofac 98: 91e95, 1997 Wong JY, Oh AK, Ohta E, Hunt AT, Rogers GF, Mulliken JB, et al: Validity and reliability of craniofacial anthropometric measurement of 3D digital photogrammetric images. Cleft Palate-Craniofacial J 45: 232e239, 2008 Yáñez-Vico RM, Iglesias-Linares A, Torres-Lagares D, Gutiérrez-Pérez JL, SolanoReina E: Three-dimensional evaluation of craniofacial asymmetry: an analysis using computed tomography. Clin Oral Investig 15: 729e736, 2011
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Soft tissue response and facial symmetry after orthognathic surgery Kai Wermker a, *, Johannes Kleinheinz b, Susanne Jung b, Dieter Dirksen c a
Fachklinik Hornheide, Department of Cranio-Maxillofacial Surgery, Dorbaumstrasse 300, 48157 Muenster, Germany University Hospital Münster, Department of Cranio-Maxillofacial Surgery, Waldeyerstraße 30, 48149 Muenster, Germany c University Hospital Münster, Department of Prosthetic Dentistry and Biomaterials, Waldeyerstraße 30, 48149 Muenster, Germany b
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 28 August 2013 Accepted 6 January 2014
Objective: In orthognathic surgery aesthetic issues and facial symmetry are vital parameters in surgical planning. Aim of this investigation was to document and analyze the results of orthognathic surgery on the base of a three-dimensional photogrammetric assessment, to assess the soft tissue response related to the skeletal shift and the alterations in facial symmetry after orthognathic surgery. Patients and methods: In this prospective clinical trial from January 2010 to June 2011, 104 patients were examined who underwent orthognathic surgery due to mono- or bimaxillary dysgnathia. The standardized measurements, based on optical 3D face scans, took place one day before orthognathic surgery (T1) and one day before removal of osteosynthesis material (T2). Results: Soft tissue changes after procedures involving the mandible showed significant positive correlations and strong soft tissue response (p < 0.05). The midfacial soft tissue response after maxillary advancement was only of minor extent (p > 0.05). The facial surfaces became more symmetric and harmonic with the exception of surgical maxillary expansion, but improvement of facial symmetry revealed no statistical significance. Conclusion: Soft tissue response after orthognathic surgery and symmetry are only partially predictable, especially in the maxillary and midfacial region. Computer programs predicting soft tissue changes are not currently safely reliable and should not be used or with caution to demonstrate a patient potential outcome of surgery. Ó 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Keywords: Symmetry Orthognathic surgery Soft tissue changes Three-dimensional Face scan Profile
1. Introduction In the planning of skeletal orthognathic correction, aesthetics and matters of attractiveness are of vital importance to the patients. A retrospective analysis of 299 patients at the University Hospital Muenster showed that for 49.5% of the women and for 34.7% of the male patients aesthetics and looks were one of the determinative reasons for surgical intervention (Wesseling, 2004). To allow for optimal functional and visual results the surgical planning should be based on reliable prognostic methods (AboulHosn Centenero and Hernández-Alfaro, 2012; Donatsky et al., 2009; Falter et al., 2012). So far the diagnosis and surgical
* Corresponding author. Fachklinik Hornheide at the Westfalian Wilhelms University Muenster, Department of Cranio-Maxillofacial Surgery, Head and Neck Surgery, Dorbaumstrasse 300, 48157 Muenster, Germany. Tel.: þ49 251 3287 421; fax: þ49 251 3287 424. E-mail addresses: [email protected], [email protected] (K. Wermker).
preparation are based on techniques that come with restrictions in terms of detailed imaging and depth of focus. In general they are associated with radiologic diagnostics and radiation exposure (Kim et al., 2013; Park et al., 2013, 2012; Yáñez-Vico et al., 2011). The current three-dimensional measurement systems have not gained acceptance for routine use yet due to either enormous technical charges or a high radiation. The aim of this investigation was to enhance the prognostic predictability of the outcomes of orthognathic surgery. The analysis of the soft tissue response to skeletal movement was the underlying technique. A three-dimensional optical measurement system was applied, that is based on the fringe projection technique and does not depend on an X-ray technique. In general symmetry is assessed by portrait photography, symmetrical deviations in all three dimensions can thus be not analyzed. Another tool used to analyze symmetry and to make a prognosis of soft tissue response of patients’ faces is based on a laser technique (Shimomatsu et al., 2012). Holberg et al. compared laser-
1010-5182/$ e see front matter Ó 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jcms.2014.01.032
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
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K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
based profile predictions to an established 2D-technique relying on cephalometric data. Whereas laser-based prognosis came with a mean variation of 0.32 mm regarding the horizontal plane the 2D prediction showed a mean deviation of 0.75 mm and thus was clearly inferior (Holberg et al., 2005). Comparable investigations underlined the fact that a calculation of soft tissue response is extremely difficult and highly unreliable. Joss et al. see the problems in poor study designs and a lack of standardized measurement techniques. Another crucial point is the enormous individual variability of the soft tissue response depending on different morphology, thickness and elasticity of the tissues (Joss et al., 2010). In this study a three-dimensional symmetry index (3D-SI) was established to objectively compare facial symmetry before and after orthognathic surgery. The relevant questions were: Is there a significant correlation between sagittal soft tissue response and skeletal movement based on the orthognathic planning? Is orthognathic surgery able to increase and improve facial symmetry?
2. Material and methods 2.1. Patients and investigations For this prospective study orthognathic patients with planned surgical correction of dysgnathia over a one and a half year period (from January 2010 to June 2011) were recruited consecutively, including all forms of dysgnathia and operative procedures. Exclusion criteria were age below 18 years, unwillingness to participate in the study and those with orthognathic operations prior to the newly planned procedure. All patients gave their informed written consent for participating in this study and the study was performed in accordance with the guidelines for good clinical practise (GCP). In addition to general health status and characteristics of the dysgnathia, the planned translocation was assessed with The University of Muenster model surgery system for orthognathic surgery (KD-MMS)”, as described below. One day before operation a preoperative face scan was performed and the preoperative threedimensional (a-)symmetry index (3D-SI) was calculated (see description below). Postoperative assessment by face scan took place one day before removal of osteosynthesis material to prevent confounding due to swelling, and the postoperative 3D-SI was calculated. For 12 distinct facial points, change (distance in mm) was measured between pre- and postoperative face scan. All these procedures are described in more detail in the following section of the paper. 2.2. Assessment of dental and skeletal jaw movement The distance of movement of the jaws through the orthognathic procedure was planned according to KD-MMS (Ehmer et al., 2013; Wiechmann et al., 1997). With the use of plaster casts, exact threedimensional positioning of maxilla and/or mandible was planned preoperatively and formed the basis for the splints used intraoperatively. Philosophy and procedures of this system were previously described in detail (Ehmer et al., 2012). As a result of the KD-MMS tool, exact planned movement of distinct points of the upper and lower dental arch and jaw can be measured. For the purposes of this study, only the sagittal changes of the following 5 points in each jaw (10 points in total) were considered for further analysis: right first molar, right cuspid, centre (midline, between incisors), left cuspid and left first molar.
Negative distances mean a setback procedure, positive values represent forward movements/advancement. 2.3. 3D scanning system The 3D scanning system is based on the fringe projection technique and has been developed at the Department of Prosthetic Dentistry and Biomaterials at the Westfalian Wilhelms University of Muenster and its technique and principles were described previously in detail (Bischoff et al., 2007; Dirksen et al., 2002; Westhäuser et al., 2008). The system enables a three-dimensional face scan with accurate skin colour assessment (true colour rgb model) using only normal visible light without any type of ionizing radiation. Over 1.5 s 200,000 to 800,000 3D-points can be assessed. Measurement accuracy of these 3D-coordinates is approximately 0.6 mm in X-axis and 0.2 mm in Y-axis within a field of 600 mm 450 mm. 2.4. Calculation of the 3D-symmetry index (3D-SI) For objective assessment and measurement of asymmetry, a special three-dimensional Symmetry Index (3D-SI) was calculated on the basis of the optically acquired data as follows: The procedure is based on the proposals of a research group at the University of Erlangen (Hartmann et al., 2007; Nkenke et al., 2006). First the original 3D-dataset (“original cloud”) is mirrored automatically at the medianesagittal plane to generate a “mirrored cloud”. Afterwards, the original and mirrored cloud are matched. Registration is performed automatically by the software, using an iterated-closest-point-algorithm that matches both clouds with the lowest achievable distance from each other. The 3D-SI is calculated from the mean of all distances between original and mirrored cloud (a) and the cross-section dimension of the face (d) to overcome differences between smaller and greater faces, using the following formula: 3D-SI [ (a/d) 3 1000. In a perfectly symmetric face, the 3D-SI would be 0. The greater the value of the 3D-SI is, the more asymmetric is the face. This easy to calculate symmetry index therefore enables an objective assessment of facial symmetry. In previous studies we proved a good correlation of the 3D-SI with perceptually judged symmetry and attractiveness (Krückemeier, 2013). For visualization of asymmetries, a false-colour image can be generated, showing the asymmetric regions of the face in warmer colours (yellow and red, see Fig. 1). 2.5. Measurement of profile changes To assess profile changes of the facial soft tissue after the orthognathic operation, pre- and postoperative face scan clouds were also matched to each other. A rough overlap was made manually by marking 7 corresponding points (medial and lateral canthus of both eyes, nasal tip and left and right angle of mouth). For fine adjustment, areas assumed not to be affected by the operation (orbita and eyes, brows and forehead) were matched to each other for minimal distance between each other by a computed iterative algorithm. Different section planes were generated: 3 vertical section planes perpendicular to the bipupillary plane (through the left pupil, through the mediane sagittal plane in the half of the bipupillary distance and through the right pupil) and 4 horizontal planes parallel to the bipupillary plane (and therefore perpendicular to the vertical planes) through the mediansagittal points Subnasale (SN, junction between nasal columella and upper lip), Upper Lip (UL, most anterior point of the upper lip), Lower Lip (LL, most anterior point of the lower lip) and Pogonion molle (PM, most anterior point of
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
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Fig. 1. Example of visualization of asymmetric parts of the face (three-dimensional cloud with false colour overlay, scale in mm) showing pre- and postoperative situations in comparison. Symmetry improved from a preoperative 3D-SI of 3.87 (left) to a more favourable 3D-SI of 2.82 (right).
the chin) were generated. As a result in each cloud (pre- and postoperative face scan) at the cut-points of vertical and horizontal planes the 12 landmarks were created (for each above mentioned point two paramedian ones (right and left side) and one mediansagittal point). Fig. 2 illustrates the scheme of preand postoperative profile lines and their sections/cut-points. The distance between the corresponding pre- and postoperative points was measured in millimetre in sagittal direction (again, negative distances mean a setback procedure, positive values represent forward movements/advancement).
2.6. Statistical analysis To assess significance of differences between different groups of patients (e.g. according to gender, type of dysgnathia or performed operative technique), Chi-square test and Fisher’s exact test were applied for categorical variables, for metric parameters Kruskale Wallis-H test was used as non-parametric test for not normally distributed data and analysis of variance (ANOVA) with post hoc Tamhane T2 test was used for normally distributed variables. Comparison of pre- and postoperative metric variables was done with the Wilcoxon matched pairs test for non-normally distributed data, in normally distributed variables t-test for joined variables was used. Analysis of correlations between jaw translocation (planned distance according to KD-MMS procedure at the different dental regions as described above) and distances between the pre- and postoperative three-dimensional face scan for above described landmarks were tested on significance using Spearman’s correlation analysis. All statistical analyses were performed by a statistician using the Statistical Package for Social Sciences (SPSS), version 16.0 for WindowsÒ (SPSS Inc., Chicago, Illinois, USA). 3. Results 3.1. Study population
Fig. 2. Scheme of pre- (blue) and postoperative (green) profile lines and their sections/ cut-points.
In total 104 patients (62 females, 42 males) with a mean age of 26.6 years (SD 8.4 years) were included into the study. 50 patients suffered from mandibular retrognathia, 42 had a prognathic mandible and in 12 patients the lower jaw had a correct skeletal position. In the upper jaw, 48 patients showed maxillary retrognathia, 1 patient had a maxillary prognathia, 10 patients suffered from transversal hypoplasia of the maxilla and in 45 patients we found no skeletal dysgnathia of the upper jaw. 41 patients received an isolated operation of the lower jaw (bilateral sagittal split ramus osteotomy according to Obwegeser-DalPont, BSSRO), in 5 patients only the maxilla was translocated (LeFort-I osteotomy), in 48 patients a bimaxillary orthognathic procedure (BSSRO þ LeFort-I osteotomy, BIMAX) was performed and 10 patients received surgically assisted rapid maxillary expansion by transpalatinal distraction (SARME/TPD after subtotal LeFort-I osteotomy). The main groups of sagittal movement were maxillary advancement (n ¼ 51, mean distance ¼ 3.62 mm), mandibular advancement (n ¼ 58, mean distance ¼ 5.18 mm) and
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
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K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
Table 1 According to the KD-MMS procedure planned dental and skeletal movement (explanation see text). Planned movement ad distinct dental points RFM
RC
Maxillary advancement (n [ 51) Mean [mm] 3.46 3.51 SD [mm] 2.07 2.00 Max [mm] 7.50 7.50 Mandibular advancement (n [ 58) Mean [mm] 5.33 5.40 SD [mm] 2.93 2.78 Max [mm] 13.0 13.0 Mandibular Setback (n [ 32) Mean [mm] 4.19 4.27 SD [mm] 3.35 3.27 Max [mm] 13.5 15.0
Center
LC
LFM
3.43 1.51 7.00
3.88 1.79 7.50
3.81 1.74 7.50
5.02 2.60 11.0
5.22 3.22 15.0
4.93 3.35 14.0
3.59 2.94 8.5
2.72 3.66 10.5
2.77 3.43 11.5
SD ¼ standard deviation; Max ¼ maximum movement. RFM ¼ right first molar; RC ¼ right cuspid. LFM ¼ left first molar; LC ¼ left cuspid.
mandibular setback (n ¼ 32, mean distance ¼ 3.51 mm). Detailed planned movements for the above described distinct points in the upper and lower jaw are presented in Table 1. 3.2. Profile changes The measured profile changes for the 12 facial points (SN, UL, LL and PM on the right and left side and in the median) in maxillary advancement, mandibular advancement and mandibular setback operations are shown in detail in Table 2. Profile changes represented the underlying skeletal movement and were not uniform at all assessed facial points. For maxillary advancement, largest anterior change (2.02 mm) was measured at the right SN point. For mandibular advancement, the right PM point showed the largest movement (2.78 mm). In mandibular setback cases the greatest movement was measured at left PM (5.38 mm). Results of correlation analysis showed nearly no significant (p > 0.05) and also very weak correlations (rs < 0.3) between preoperatively planned upper jaw movement and changes in soft tissue points SN and UL. A significant (p < 0.05) correlation of rs ¼ 0.311 could only be found between planned advancement of the upper first molar of the right side and the point SN median. Concerning mandibular movements, the correlations between preoperatively planned distance and soft tissue changes at the points LL and PM were all significant (p < 0.05, for some items even p < 0.01) and also stronger with correlation coefficients rs reaching from 0.333 to 0.570 (Table 3). In summary, the soft tissue changes of the upper lip and subnasale (UL, SN) only slightly followed the planned dental and skeletal movement of the maxilla between 3% and 34 % without clear and statistically significant correlations. Soft tissue changes of the lower third part of the face (points LL and PM) are much more strongly correlated with the underlying planned mandibular movement. The extent of soft tissue changes lay between 52% and a maximum of up to 130% (at the point PM) of the planned lower jaw translocation. The region of the Pogonion (PM points, especially PM median) showed best correlations and highest extent of hard tissue follow. 3.3. Symmetry analysis Considering the whole study population of 104 participants, symmetry improved, but this did not reach statistical significance better than on a 10% level (p ¼ 0.072). Mean preoperative 3D-SI was 3.58 (SD ¼ 1.52), mean postoperative 3D-SI was 3.34 (SD ¼ 1.05), so
the mean improvement was 0.24 (SD ¼ 0.98, 95% confidence interval 0.023 to 0.506). Comparing pre- and postoperative symmetry measurements differentiated according to different operation procedures (Table 4) asymmetry increased only after SARME/TPD. After BSSRO, LeFort-I osteotomy and BIMAX procedures symmetry improved, but without being statistically significant (p > 0.05). Fig. 3 illustrates the pre- and postoperative 3DSI for BSSRO alone, BIMAX and SARME/TPD groups. 4. Discussion In this investigation 104 patients were analyzed. Compared to similar trials dealing with hard and soft tissue alterations after
Table 2 Sagittal soft tissue changes at different facial points after different types of sagittal jaw translocations. Soft tissue change at facial point
Skeletal jaw translocation Maxillary advancement
Mandibular advancement
Mandibular setback
n
51
58
32
SN right Mean [mm] SD [mm] Max [mm] SN median Mean [mm] SD [mm] Max [mm] SN left Mean [mm] SD [mm] Max [mm] UL right Mean [mm] SD [mm] Max [mm] UL median Mean [mm] SD [mm] Max [mm] UL left Mean [mm] SD [mm] Max [mm] LL right Mean [mm] SD [mm] Max [mm] LL median Mean [mm] SD [mm] Max [mm] LL left Mean [mm] SD [mm] Max [mm] PM right Mean [mm] SD [mm] Max [mm] PM median Mean [mm] SD [mm] Max [mm] PM left Mean [mm] SD [mm] Max [mm]
2.02 2.10 5.7
1.69 2.21 4.2
1.30 3.48 2.9
0.07 1.48 2.4
0.08 1.44 2.6
0.03 1.05 1.5
1.24 1.37 3.5
1.37 1.41 2.7
0.35 2.62 2.4
1.23 2.05 4.5
1.67 1.70 3.4
0.18 3.63 3.5
0.81 1.89 4.0
1.25 2.04 3.1
0.06 1.84 2.8
1.15 2.10 7.8
2.42 3.41 3.5
1.50 3.49 2.6
0.31 3.49 5.9
1.08 2.23 8.3
2.27 4.08 9.2
1.12 5.24 8.6
1.35 3.90 7.2
3.15 5.52 10.3
0.67 3.89 5.9
1.10 3.95 8.3
2.60 3.96 9.0
0.85 6.68 6.1
2.78 3.14 9.7
3.85 9.14 20.3
0.89 4.39 5.8
1.27 3.70 10.3
2.62 4.28 9.2
1.33 6.07 7.9
1.97 6.22 12.3
5.38 5.48 13.8
SD ¼ standard deviation; Max ¼ maximum movement. SN ¼ Subnasale; UL ¼ upper lip. LL ¼ lower lip; PM ¼ Pogonion molle.
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7 Table 3 Results of correlation analysis (Spearman correlation coefficient rs) between soft tissue changes of the lower third part of the face in orthognathic operations of the mandibula. Soft tissue change
Planned movement ad distinct dental points RFM
RC
Center
LC
LFM
LL right LL median LL left PM right PM median PM left
0.385** 0.382** 0.464** 0.495* 0.500** 0.532**
0.390** 0.377** 0.500** 0.563** 0.540** 0.574**
0.375** 0.362** 0.540** 0.572** 0.527** 0.544**
0.403** 0.333** 0.529** 0.543** 0.528** 0.449**
0.375** 0.349** 0.535** 0.543** 0.518** 0.427*
Significance: *p < 0.05; **p < 0.01. SN ¼ Subnasale; UL ¼ upper lip. LL ¼ lower lip; PM ¼ Pogonion molle. RFM ¼ right first molar; RC ¼ right cuspid. LFM ¼ left first molar; LC ¼ left cuspid.
orthognathic surgery this number provides a sound base for the deduction of conclusive results referring to different kinds of orthognathic surgery and the respective diagnosis. Whereas Björk et al. included 32 patients in their analysis, Naoumova et al. assessed 42 probands and Chew et al. a group of 30 persons (Björk et al., 1971; Chew et al., 2008; Freihofer, 1976; Naoumova et al., 2008). Drescher et al. and Noell et al. dealt with groups of 136 and 165 patients (Drescher et al., 1990; Noell, 1999). The size of the study group containing over hundred patients provides a solid data basis for convincing results especially as different surgical procedures are compared. In the aforementioned investigations the assessment of the soft tissues and profile relies on different skeletal landmarks presented in the lateral cephalogram. The chosen references vary strongly between the different trials, so a standardized procedure with an analogous technique cannot be indentified (Björk et al., 1971; Chew et al., 2008; Dolce et al., 2003; Drescher et al., 1990; Freihofer, 1976; Naoumova et al., 2008; Noell, 1999). In contrast to the majority of studies dealing with similar issues, the data in this trial results from dental reference points and a three-dimensional, investigator-independent photogrammetric study. One key-advantage of this kind of measurement lies in the additional information retrieved from the analysis of the paramedian plane in addition to the median plane. Considering the relevance of the prominence of the zygomatic arch in evaluating facial symmetry, the information on this paranasal area is of crucial importance. Table 4 Comparison of pre- and postoperative three-dimensional symmetry index (3D-SI) for different surgical procedures. OP-Procedures
3D-Symmetry index (3D-SI)
Sign.
Pre-OP
Post-OP
(p-value)
2.99 0.91
(0.550)
2.94 0.84
(0.655)
3.56 1.17
(0.131)
3.57 0.90
(0.378)
Only BSSRO (n [ 41) Mean 3.05 SD 0.90 Only LeFort-I osteotomy (n [ 5) Mean 3.08 SD 1.09 BIMAX (n [ 48) Mean 3.99 SD 1.81 SARME/TPD (n [ 10) Mean 3.43 SD 1.13
5
Current literature underlines the fact that stereophotogrammetry represents an easily applicable, quick, noninvasive and precise technique of facial surface scanning. With a record time of 1.5 s the resolution capacity ranges between 0.2 mm and 0.6 mm. Other publications that emphasized the advantages of 3D photogrammetry have come from Hoefert et al., Wong et al. and de Menezes et al.: they too described the technique as reliable, reproducible and a radiation-free tool for orthodontic diagnostics (de Menezes et al., 2010; Hoefert et al., 2010; Wong et al., 2008). This combination of quick precision, tolerance and additional information qualifies the photogrammetric technique as a helpful analytic tool in orthognathic diagnosis, treatment planning and surgical follow-up. One outstanding result in this data is the fairly moderate soft tissue response of the midface after maxillary movement even if skeletal maxillary and mandibular shifts follow similar distances. A possible explanation might lie in the characteristic surgical procedure, when a part of the anterior nasal spine is reduced to harmonize the bony profile, especially when the maxilla moves forward. So the maxillary skeletal shift is indirectly reduced, resulting in a minor soft tissue response. Another reason for the exceptionally low levels of soft tissue response after maxillary correction may be seen in the applied matching procedure. The eye and nose area are defined as constant regions, where the pre- and postoperative data clouds are matched congruently. Due to this specialty of the applied technique the changes of the near midfacial soft tissues might become not as prominent as the soft tissue response in the more distant mandibular regions. Generally the midface soft tissues respond less perceptibly to skeletal alterations. The improvement of facial aesthetics including the correction of asymmetric features is often one of the reasons why patients seek to surgical intervention. This study underlines the fact that orthognathic surgery results in more facial symmetry as is documented in current literature. The relevance of symmetry for a more pronounced attractiveness is controversially discussed (Borelli and Berneburg, 2010). Braun et al. concluded that symmetry alone does not automatically define beauty but asymmetry on the other hand makes a face less attractive (Braun et al., 2001). Patients suffering from malocclusion often show less symmetric features (Sforza et al., 2007). A statistically significant increase of symmetry by surgical correction as described in the literature was not confirmed by the data analyzed (Ferrario et al., 1999; Hajeer et al., 2004; Ko et al., 2009), though a general tendency to more symmetric faces after orthognathic surgery was revealed especially regarding the lower facial third. Whereas stereophotogrammetry is a dependable method for analysis facial soft tissues, the photogrammetric technique so far does not provide the technical base for a reliable morphologic prediction of soft tissue reaction to the skeletal shift to present the probable outcome. In agreement with other researchers, we conclude from our results that using radiation free optical surfaces data and three-dimensional software based analysis (e.g. of symmetry) provides a fast, detailed and physically undemanding tool of measurement (Choi et al., 2013; Stauber et al., 2008). Stereophotogrammetry therefore serves as an apt addition to orthognathic diagnostics with the special advantage of three-dimensional imaging in contrast to X-ray diagnostic or photography. 5. Conclusion
SD ¼ standard deviation. BSSRO ¼ bilateral sagittal split ramus osteotomy (only mandibula). BIMAX ¼ bimaxillary procedure (BSSRO þ LeFort-I osteotomy). SARME/TPD ¼ surgically assisted rapid maxillary expansion/transpalatinal distraction.
With the exception of surgically assisted rapid maxillary expansion and transpalatinal distraction (SARME/TPD), mono- or bignathic orthognathic surgery can be expected to improve facial symmetry. The soft tissue response after orthognathic surgery and the amount of symmetry changes are only partially predictable,
Please cite this article in press as: Wermker K, et al., Soft tissue response and facial symmetry after orthognathic surgery, Journal of CranioMaxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/j.jcms.2014.01.032
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K. Wermker et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e7
Fig. 3. Boxplots of pre- and postoperative measured three-dimensional symmetry index (3D-SI) in different groups of orthognathic surgery (explanations see text).
especially in the maxillary and midfacial region. Whereas the lower face and mandibular region showed high, and therefore more predictable, correlations between hard and soft tissue changes, correlations are weak in the maxilla and midface. Computer programs predicting soft tissue changes are not currently reliable and should not be used, or should be used with caution, to demonstrate to a patient the potential outcome of surgery. Authors contributions KW developed the conception and design of the study, helped to analyze the data and drafted the manuscript. SJ performed data analysis, performed data interpretation, and helped to draft the manuscript. JK revised the article critically, gave important intellectual content and gave final approval to the manuscript. DD developed the optical scanning system, made substantial intellectual contributions and helped in conception of the study. Sponsorship There was no financial or material support for this study by any company. Role of funding sources None. Conflict of interest There were no financial and personal relationships with other people or organizations that could inappropriately influence (bias) our work. All authors declare that there is no conflict of interest. Acknowledgements We thank Anna Sehrbrock for helping in data acquisition and performing the optical face scan. References Aboul-Hosn Centenero S, Hernández-Alfaro F: 3D planning in orthognathic surgery: CAD/CAM surgical splints and prediction of the soft and hard tissues results e our experience in 16 cases. J Craniomaxillofac Surg 40: 162e168, 2012 Bischoff G, Böröcz Z, Proll C, Kleinheinz J, von Bally G, Dirksen D: Modular optical topometric sensor for 3D acquisition of human body surfaces and long-term monitoring of variations. Biomed Tech (Berl) 52: 284e289, 2007
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