Article_5_2_3
ORTHODONTICS
SOFT-TISSUE FACIAL ASYMMETRY BEFORE AND AFTER ORTHOGNATHIC SURGERY:
Original Article
APPLICATION OF A NEW 3D PROTOCOL
Filippo Da Pozzo1,2a, Francesca M.E. Rusconi1b, Giada Anna Beltramini2c, Daniele M. Gibelli1d, Valentina Pucciarelli1e,
Aldo Bruno Giannì2,3f, Chiarella Sforza1g
1
LAFAS, Laboratory of Functional Anatomy of the Stomatognathic System, Department of Biomedical Sciences for Health, Università degli Studi di Milano,
Milan, Italy
2
Maxillofacial and Dental Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico di Milano, Milan Italy
3
Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan Italy
a
MD
b
DDS
c
MD, PhD
d
MD, PhD, ORCID 0000-0002-9591-1047
e
MBiothec, PhD, ORCID 0000-0002-9165-133X
f
MD, PhD
g
MD, PhD, ORCID 0000-0001-6532-6464
ABSTRACT DOI: 10.25241/stomaeduj.2018.5(2).art.3
Introduction: Skeletal Class III patients often present a major facial asymmetry. In the
current investigation, a quantitative method to assess 3D facial asymmetry was applied OPEN ACCESS This is an Open Access
article under the CC BY-NC 4.0 license.
to an orthognathic surgery patient to quantify possible postsurgical modifications. Peer-Reviewed Article
Methodology: Soft-tissue facial scans of a 20-year-old man with skeletal Class III,
Citation: Da Pozzo F, Rusconi FME, Beltramini
candidate to orthognathic surgery, were collected in the pre-surgery stage and 6, 12, 24 GA, Gibelli DM, Pucciarelli V, Giannì AB, Sforza C.
months post-surgery with a stereophotogrammetric system. Soft tissue asymmetry was Soft-tissue facial asymmetry before and after
orthognathic surgery: application of a new 3D
calculated in the facial thirds according to a published protocol (J Craniomaxillofac Surg protocol. Stoma Edu J. 2018;5(2):98-101.
2017;45(1):76-81), and the relevant time-related modifications described. The results Academic Editor: Constantinus Politis, MD,
were also compared to normal values from a group of 23 control subjects (10 men, 13 DDS, MM, MHA, PhD, Professor & Chairperson,
women, mean age 26) by using z-scores. University of Leuven, Leuven, Belgium
Results: The longitudinal analysis of the soft-tissue facial asymmetry showed a marked Received: January 25, 2018
Revised: March 14, 2018
difference in the analysed time points: orthognathic surgery did reduce facial symmetry Acccepted: June 06, 2018
in the present patient. The comparison between the patient and the control subjects Published: June 07, 2018
by using z-scores highlighted a clear difference in all-time points: the patient with facial *Corresponding author: Professor Chiarella
dysmorphia had a higher degree of asymmetry than healthy subjects. Sforza, MD, PhD, Department of Biomedical Sci-
ences for Health, University of Milan, Milan, Italy,
Conclusion: The measurements of soft-tissue facial asymmetry using 3D optical via Mangiagalli 31, I-20133 Milano, Italy, Tel: +39
digitisers can provide clinically useful information. The graphical representation of – 02 503 15385, Fax: +39 – 02 503 15387, e-mail:
chiarella.sforza@unimi.it
results can help in the patient’s understanding of the treatment phases, thus increasing
compliance. Copyright: © 2018 the Editorial Council for the
Stomatology Edu Journal.
Keywords: face, soft tissues, orthognathic surgery, symmetry.
1. Introduction surgeons, the orthodontists and the patients, allowing
Facial dysmorphoses are not common in the western the best compliance especially for treatments that
world. According to US studies, dentoskeletal Class III require several interventions, and that need a middle
patients can be found in 0.6% of the general population, term follow up to show their final results [6,7].
a much smaller value than that reported for dentoskeletal Current technology offers a wide range of computerized
Class II patients, which is around 10% [1]. optical scanners that can be used to assess facial soft
Nonetheless, Class III patients often present more tissues not invasively, providing a 3D, quantitative
complex situations than Class II ones, with a much reproduction of the patients’characteristics [8].The digital
more altered facial function and aesthetics, and images can be evaluated longitudinally to appreciate the
the percentage of patients undergoing surgical effects of the various phases of the treatment [6] and can
interventions is approximately 6-7 times larger in Class III be compared to those obtained from normal subjects of
than in Class II subjects (about 33% vs. 5%) [1]. Apart from comparable age, sex and ethnicity.
the restoration of a sound functionality and a normal Indeed, the need for reference values is important,
occlusion, aesthetics and facial symmetry are among as a slight facial asymmetry is also present in healthy
the most important aspects in modern orthognathic subjects [9-11], and even the best surgical and
surgery [2]. The successful attainment of an aesthetically orthodontical approaches cannot restore a perfectly
acceptable result starts from correct skeletal and dental symmetrical appearance. In the present study, we
positions [3-5], but it needs a thorough evaluation of the evaluated the soft tissue facial asymmetry of a patient
facial soft tissues [1,2]. The external appearance of the undergoing a combined surgical-orthodontic treatment
face is also the key point for a fruitful dialogue among the to correct a Class III dento-skeletal malocclusion. 3D
98 Stoma Edu J. 2018;5(2): 98-101 http://www.stomaeduj.com
SOFT-TISSUE FACIAL ASYMMETRY BEFORE AND AFTER ORTHOGNATHIC SURGERY:
APPLICATION OF A NEW 3D PROTOCOL
morphometric measurements were performed on
Original Article
digital stereophotogrammetric images, and facial soft
tissue asymmetry quantified. Data were obtained
longitudinally and compared to those obtained in
healthy, control subjects.
2. Materials and methods
The facial soft tissues of a 20-year-old man were
imaged by using the VECTRA M3 3D Imaging System
(Canfield Scientific, Fairfield, NJ, USA). The instrument is
a stereophotogrammetric unit made up of three pods.
In each pod, there are two cameras that photograph
the subject’s face from different points of view (Fig. 1).
A previous calibration permits to obtain the metrical
data of the facial surface (from ear to ear, from trichion Figure 1. VECTRA M3 3D Imaging System (Canfield Scientific, Fairfield, NJ,
to neck) in a few milliseconds. Files can be exported USA): the three pods that surround the subject can be seen.
and elaborated with proprietary and custom software.
In particular, the Mirror® Vectra Software (Canfield
Scientific, Fairfield, NJ, USA) was used in the present
investigation [4].
The patient had a diagnosis of skeletal Class III
dysmorphism and was a candidate for a surgical
intervention of bimaxillary osteotomy. The patient was
analysed in 4 different stages (preoperative, at the end of
orthodontic treatment, and postoperatively 6, 12 and 24
months after surgery). On each occasion, he was imaged
while seating with a natural relaxed expression (closed
lips, teeth in slight contact).
A group of 23 subjects were selected from the
Laboratory archive to form the control group (13 females
and 10 males, mean age 26, SD 6.8 years); they all had
a diagnosis of dentoskeletal Class I and no history of
traumas or alterations in the facial bones. Acquisitions
were obtained after the patients’ written informed
consent and did not involve any invasive, painful or
dangerous procedure. All procedures were performed as
previously described in the literature [12,13]. In brief, on
each facial image, a set of 50 anthropometric landmarks
were identified and digitized. Afterwards, following the
protocol validated by Codari et al. [3], the anterior part of
the face was delimitated by the following 10 landmarks:
trichion (tr); right and left frontotemporal (ft); right and
left zygion (zy); right and left tragion (t); right and left Figure 2. Landmarks used for symmetry analysis. (Written consent for the
publication of this image was obtained).
gonion (go); gnathion (gn) (Fig. 2).
Each half-face was split into three thirds (upper, middle The work described was carried out in accordance with
and lower part); the mid facial plane of maximum The Code of Ethics of the World Medical Association
symmetry was automatically obtained, and the two (Declaration of Helsinki). Informed consent was obtained
facial halves superimposed. The software automatically from all patients, and their privacy rights observed. Ethi-
calculated the Root Mean Square (RMS) distance values cal approval was given by University ethics review board.
among the two facial halves separately for each facial
third, thus providing a set of symmetry values. The
lower the value, the higher the symmetry. Ideally, very 3. Results
symmetrical areas should have an RMS value of 0. Table 1 illustrates the time-related variations in facial
To assess the longitudinal modifications, the preopera- asymmetry in the analysed patient. A trend of improve-
tive image was superimposed on those obtained at 6, 12 ment in his facial symmetry was observed during the
and 24 months after the intervention, and RMS values follow-up examinations.
obtained. The software also produced colorimetric maps With regards to the lower third of the face, the RMS value
which highlight the modifications in an intuitive way. obtained from the overlap of the pre-surgical images
The same procedures were followed for the subjects of of the two hemifaces was 1.2 mm; this value decreased
the control group, and descriptive statistics (mean, SD) in the subsequent acquisitions made after 6, 12 and 24
were obtained for regional facial asymmetry and used to months. A reduction in the RMS values was also found in
calculate z-scores (Patient value minus reference mean the middle and upper facial thirds.
value divided by reference SD). The smaller the z-score, When the facial asymmetry of the patient was compared
the similar the patient is to the control group. to that of healthy, reference subjects using z-scores, a
IRB Approval trend of improvement was seen after surgery (Fig. 3). The
Stomatology Edu Journal 99
SOFT-TISSUE FACIAL ASYMMETRY BEFORE AND AFTER ORTHOGNATHIC SURGERY:
APPLICATION OF A NEW 3D PROTOCOL
Original Article Table 1. Time-related variations in facial asymmetry in the analysed
patient (mm). The larger the value, the more asymmetrical the patient.
RMS 6 RMS 12 RMS 24
RMS PRE
months months months
Upper third
0.887 0.753 0.831 0.876
(forehead)
Middle third
1.300 0.640 0.691 0.813
(maxilla)
Lower third
1.213 0.699 0.699 0.974
(mandible)
Figure 3. Z-scores of the analysed patient during the 24-months follow
up.
z-score value calculated in pre-surgical acquisitions was
1.28 SD for the lower third, 1.79 SD for the middle third Figure 4. Localised asymmetry in the upper, middle and lower parts of
and 0.38 SD for the upper third; 24 months after surgery the face in the analysed patient. The pre-surgical image is compared to that
the z-score was 0.52 SD for the lower third, 0.18 SD for obtained at the 24 months follow up..
the middle and 0.37 SD for the upper one. more than 6 months [15].
To better assess the localised facial asymmetry, Fig. 4 Generally, patients with skeletal dysmorphia are more
presents the asymmetry divided in the upper, middle asymmetrical than healthy subjects without malocclu-
and lower parts of the face in the analysed patient. The sions [9,16], as shown in the current analysis that allowed
pre-surgical image is compared to that obtained at the to localize those parts of the face showing a higher de-
24 months follow up. The software produces a colori- gree of left-right imbalance. The present method can,
metric map which highlights the variations in an intui- therefore, be coupled with the conventional analyses of
tive manner. The major differences are represented in facial esthetics [17], thus increasing the quantitative de-
red and in blue, respectively by default and in excess. scription of the patient, and helping in treatment plan-
The unvaried areas are coloured in green. As expected ning and monitoring of follow up.
the degree of asymmetry is reduced in every third of the
face and the best results are seen in the lower third.
5. Conclusion
The measurements of soft-tissue facial asymmetry using
4. Discussion 3D optical digitisers can provide clinically useful infor-
In the current investigation, we performed a longitudi- mation. The graphical representation of results can help
nal evaluation of soft-tissue facial asymmetry in a patient in the patient’s understanding of the treatment phases,
candidate for bimaxillary surgery for a skeletal Class thus increasing compliance.
III malocclusion. The method used a set of stereopho-
togrammetric facial scans, and it allowed a complete
picture of the modifications of the patients’ soft tissues: Author Contributions
orthodontists and surgeons are thus provided with an FP: Conception and design of the study; Acquisition
extra tool to plan and monitor the clinical outcome. An of data; Analysis and interpretation of data collected;
additional advantage is the patient-friendly depiction Drafting of the article; Final approval. FMER: Acquisition
of the results which can enhance the patient’s compre- of data; Analysis and interpretation of data collected;
hension of the various treatment phases, with increased Drafting of the article; Final approval. GAB: Acquisition
compliance [6]. of data; Analysis and interpretation of data collected;
The acquisitions were made with a middle term follow Drafting of the article; Final approval. DMG: Acquisition
up, starting in the preoperative (post orthodontic) phase, of data; Analysis and interpretation of data collected;
and subsequently 6, 12 and 24 months after surgery. The Drafting of the article; Final approval. VP: Analysis and
24-months stage allowed stable facial images of the interpretation of data collected; Drafting of the article;
patients to be obtained, without the transient effects Final approval. ABG: Conception and design of the
of surgery on soft tissues edema and the post-surgical study; Analysis and interpretation of data collected;
orthodontic treatment [1,14]. Indeed, despite the vari- Critical revision of article; Final approval. CS: Conception
ety of studies on 3D facial asymmetry after bimaxillary and design of the study; Analysis and interpretation of
orthognathic surgery, few were longitudinal and lasted data collected; Critical revision of article; Final approval.
100 Stoma Edu J. 2018;5(2): 98-101 http://www.stomaeduj.com
SOFT-TISSUE FACIAL ASYMMETRY BEFORE AND AFTER ORTHOGNATHIC SURGERY:
APPLICATION OF A NEW 3D PROTOCOL
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Original Article
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Filippo DA POZZO
MD
LAFAS, Laboratory of Functional Anatomy of the Stomatognathic System
Department of Biomedical Sciences for Health, University of Milan
via Mangiagalli 31, I-20133 Milano, Italy
CV
Filippo Da Pozzo, MD, graduated in 2017 with the highest grades in Medicine and Surgery at the University of Milan. Since
2015 he has been attending the university department of Oral and Maxillofacial surgery at the polyclinic hospital Fondazione
IRCCS Ca' Granda in Milan. He is currently a member of the research staff in the Laboratory of Functional Anatomy of the
Stomatognathic System - LAFAS, Department of Biomedical Sciences for Health at the University of Milan, Milan, Italy. His fields
of research are the morphological and metrical assessment of anatomical characteristics of craniofacial structures, including
their modifications with pathology and treatment.
Questions 3. In the current study we investigated
qa. Three-dimensional modifications in dental arch
1. Which instruments can be used to diameters;
qb. The effect of operator experience in making
measure soft tissue facial asymmetry? facial measurements;
qa. Bite wing radiographs; qc. The use of Computerized Tomography to
qb. Lateral plane teleradiographs; measure facial asymmetry;
qc. Stereophotogrammetric units; qd. A new protocol to assess localized soft-tissue facial
qd. Conventional orthopantomographs. asymmetry.
2. How was facial asymmetry 4. In the current investigation, we found that:
measured? qa. Soft-tissue facial asymmetry increased after
qa. Using Root Mean Square distances among dental extraction;
images; qb. Skeletal facial asymmetry decreased after
qb. Using surface electromyography; implant placement;
qc. Superimposing facial photos to Computerized qc. Soft-tissue facial asymmetry decreased after
Tomography reconstructions; orthognathic surgery;
qd. Measuring the distances between selected qd. Dental arch asymmetry increased after functional
skeletal landmarks. orthodontic treatment.
Stomatology Edu Journal 101