Comparative Evaluation of Facial Soft Tissue Changes
Original Article
Using 3D Scanning and 2D Photography in Bimaxillary
Protrusion Extraction Treatment Cases.
To cite: Akanksha Shukla,
Gurkeerat Singh, Raj
Kumar Singh, Varun
1Akanksha Shukla, 2Gurkeerat Singh, *3Raj Kumar Singh, 4Varun Goyal,
Goyal, Nishant Gupta,
5Nishant Gupta, 6Gaurav Saluja, 7Ritu Gupta
Gaurav Saluja, Ritu Gupta
1,6,7
Post-Graduate Resident, Department Of Orthodontics And Dentofacial Orthopaedics, Sudha Rustagi College
Of Dental Sciences And Research, Faridabad, Haryana, India.
Comparative evaluation of
facial soft tissue changes
2Vice Principal, Professor and Head, Department Of Orthodontics And Dentofacial Orthopaedics, Sudha
using 3D scanning and 2D
Rustagi College Of Dental Sciences And Research, Faridabad, Haryana, India.
photography in bimaxillary
protrusion extraction
3,4,5
Associate Professor, Department Of Orthodontics And Dentofacial Orthopaedics, Sudha Rustagi College Of
treatment cases.
Dental Sciences And Research, Faridabad, Haryana, India.
J Contemp Orthod 2020;4(4):
ABSTRACT
21-28.
Introduction - This prospective clinical study was undertaken to analyze the three-dimensional
facial soft tissue changes in bimaxillary protrusion extraction treatment cases using
3D
Received on:
structured light based scanner and facial photographs and to compare the two modalities.
11-11-2020
Materials and Methods -
25 Indian adult patients of 18 - 23 years of age with dentoalveolar
Accepted on:
bimaxillary protrusion malocclusion and all four premolar extraction with maximum anchorage as
20-12-2020
treatment plan were taken. A pre-operative and post- operative extra oral 3D scan and 2D
Source of Support: Nil
photographs were obtained for each subject. A prospective comparative evaluation of 12 lateral
Conflict of Interest: None
and 10 frontal soft tissue parameters was done.
Results - Significant changes were seen in distance of Sn, Pog, Ls, and Li from TVL, Ls and Li
from E line and S line, Inf sulcus to H line, Naso- labial angle, H angle, and Merrifield Z angle
(p<0.05). However no statistical difference was found between the results obtained from 3D
scan and facial photographs.
Conclusion-Significant soft tissue profile changes are obtained from pre-treatment to post-
treatment in all first four premolar extraction bimaxillary protrusion cases mainly in antero-
posterior direction. The changes observed through evaluation of scans were similar to the ones
obtained through photographs.
Key Words: Soft tissue profile changes, Extraction treatment, structured light based Scanner,
Photographs, 3D versus 2D.
owing to radiographic midsagittal projection errors.10
INTRODUCTION
Photographs provide limited information regarding the soft
In today’s world, most individuals seeking orthodontic
tissue changes and is influenced by factors such as angulation
treatment are looking for a pleasant facial profile. Improved
and direction of taking the photograph.11
soft tissue esthetics have become the primary objective of
orthodontic treatment.1
3-Dimensional
(3D) imaging techniques have been recently
Bimaxillary protrusion characterized by proclined maxillary
developed for the evaluation of facial soft tissue changes such as
and mandibular incisors is the commonest chief complaint of
Cone Beam Computed Tomography
(CBCT), Laser based
patients seeking orthodontic treatment.2 Such patients are
scanning systems and Structured light based Scanners.12
3D
routinely treated with all four first premolar extraction with
facial diagnosis gives a better visualization of facial soft tissue
maximum anchorage consideration.2-4 The soft tissue response
profile of the patient and also helps motivate the patients to
to such treatment is currently debatable. Some studies have
appreciate the changes brought by long duration orthodontic
reported a high degree of correlation between retraction of
treatments.
upper incisors and lip retraction,5-7 while others reported that a
definite proportional change in the soft tissue does not
One critical problem with most of the 3D scanning systems is its
necessarily follow changes in the dentition.8,9
cost and exposure to radiations. A structured light based scanner
is a fast processing alternative that captures photorealistic
Cephalometric radiographs and photographs have by far been
images in a non invasive manner. It makes use of ambient white
the most popular means of evaluating soft tissue changes in
light making it safe to use for young children and pregnant
extraction cases. Lateral cephalograms have an inherited
women where lasers and radiation exposure pose a great
problem of vertical and horizontal displacement of images
21
Journal of Contemporary Orthodontics, Oct-Dec 2020; 4(4):21-28
Shukla et al
biological risk.13
5.
Patients capable of maintaining good oral hygiene.
The light projector unit projects an organized pattern of grids,
dots, or stripes of white light onto the surface of the object.
EXCLUSION CRITERIA
The projected light is then captured by a camera. It uses a
6.
Patient who require habit or functional treatment.
sensor to identify how the patterns appear after being distorted
by the object under different illumination condition to
7.
Patients with a history of any congenital anomalies such as
eventually recover the 3D geometry.14
supernumerary teeth.
The structured light based scanner used in this study was a
8.
Patients who are irregular or cannot maintain proper oral
USB powered portable hand held scanner compatible with
hygiene.
Windows® 8 and 10. It uses a short range scanning technology
9.
Patients who do not give consent to be part of the study.
from Intel® with a full HD colour camera.15
METHODOLOGY
AIM
Treatment records including 2D photographs and 3D scans were
Comparative evaluation of facial soft tissue changes using 3D
made pre- and post- extraction orthodontic treatment. Patients
scanning versus 2D photography in bimaxillary protrusion
were informed about the study and their consent for participation
extraction treatment cases.
was taken. Clearance from the concerned ethical committee was
OBJECTIVES
obtained before proceeding with the study
1. To evaluate the soft tissue changes pre- and post- treatment
For the photographs:
with the help of 3D extra oral scanner and 2D photographs
Two different
2D pictures were made under standardized
in bimaxillary protrusion extraction treatment cases.
conditions in a portrait mode: one frontal and one lateral (right
2. To do a comparative evaluation of the soft tissue changes
profile) taken by DSLR camera. Photographs were taken by
recorded using scanner and photographs..
making subjects sitting upright; head in the natural posture with
the Frankfort Horizontal plane (FH plane) parallel to the floor,
MATERIALS AND METHOD
eye level behind the camera as shown in Figure 1.
Structured light-based scanner - Sense™ 3D
The photographs were standardized by using a tripod set up and
DSLR camera- Nikon™ D5600
a chair placed at 1.5 meters distance from camera lens which
Tripod Setup
was marked using a green tape as shown in Figure 2. The focal
3D analysis software- MeshLab,3D Builder™,
length was set to 70 mm to standardize the magnification also.
Photograph Analysis Software- TrackerTM. Adobe®
Photoshop 7.0
Sample size estimation: The sample size estimation was done
by using GPower software (version 3.0). The power of the
study was taken to be 80% and Confidence Interval (C.I.) of
95% (p<0.05). The sample size was estimated to be a
minimum of 8 as assessed from a similar study
Sample distribution:
25 bimaxillary protrusion orthodontic
patients within the age group of 18 to 23years indicated for
fixed orthodontic treatment with all four first premolar
Figure1: standardized photographs taken at eye level. Figure2:
Tripod setup at 1.5 metres.
extraction.
Magnification error was further removed by measuring the inter-
INCLUSION CRITERIA
pupillary distance of the patient and calibrating it in the software
1.
Patient’s in the age group of 18-23 years.
Tracker™ using a calibrating Stick. Every reading was recorded
three times by three different operators and the average reading
2.
Patient’s with Class I bimaxillary protrusion to be
was recorded in the proforma of the patient for the purpose of
treated with all 4 pre-molar extraction.
the study.Other parameters were then measured to scale in
3.
Permanent dentition with second molars erupted.
accordance to this reference measurement.
4.
No history of previous orthodontic intervention.
For the scans:
22
Scans were done by using structured light based soft tissue
RESULTS
scanner by SenseTM(figure 3)
Data was analyzed using Statistical Package for Social Sciences
Individual subjects in rest position were scanned from Ear to
(SPSS) version 21.0, IBM Inc. Descriptive data was reported for
Ear laterally and anteriorly from hairline to the most
each variable. Descriptive statistics such as mean and standard
prominent soft tissue point on the chin i.e. pogonion.
deviation for continuous variables was calculated. Shapiro Wilk
test was used to check the normality of the data. As the data was
found to be normally distributed bivariate analyses was
performed using Independent t test and paired t test. Level of
statistical significance was set at p-value less than 0.05.
Graph 1, 2 & 3 shows Pre to post treatment changes in lateral
parameters assessed through photographs.
Figure 3 Structured light based scanner. Figure 4 3D scan
The scanner was moved 180o around the patient’s face to
record facial scan. The scans were made by asking patient to
look straight ahead, keeping their heads parallel to the FH
plane. (figure 4)
Scans were internally calibrated by the sense software with
the mean error less than 1%.
The acquired 2D (TIFF file) and 3D images (.obj file) were
afterwards transferred to a computer for further analysis of
soft tissue landmarks.
Graph 1 There was a significant difference seen in parameters TVL-Sn,
QUANTITATIVE ASSESSMENT OF FACIAL
TVL- Pog, TVL-Ls, TVL-Li.
MORPHOLOGY
A total of 14 facial landmarks - were identified twice on each
of the 2D and 3D images. To place the landmarks on the 2D
images, software Trackerwas used. 3D Builderwas used
for landmark identification on the 3D images.
Following landmarks were used for frontal/ lateral analysis.
(Figure 5 and 6)
Graph 2 There was a significant difference seen in parameters E line to
Ls, E line to Li, S line to Ls, S line to Li, Inf sulcus- H line.
Figure5 Frontal analysis landmarks. Figure6 Lateral analysis
landmarks.
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Journal of Contemporary Orthodontics, Oct-Dec 2020;4(4):21-28
Shukla et al
Graph 6 There was a significant difference seen in parameters Naso-
labial angle, H angle, Merrifield Z angle.
Graph 3 There was a significant difference seen in parameters Naso-
labial angle, H angle, Merrifield Z angle.
Graph 7, 8 & 9 shows Pre to post treatment changes in Frontal
Graph 4, 5 & 6 shows Pre to post treatment changes in lateral
parameters assessed through photographs
parameters assessed through scans.
Graph 7 There was no significant difference seen in the frontal
parametersInter-pupillary, Tri-G, N-Sn, Sn-Me.
Graph 4 There was a significant difference seen in parameters TVL-
Sn, TVL- Pog, TVL-Ls, TVL-Li.
Graph 8 There was no significant difference seen in the frontal
parameters Inter- commissural, Inter alar,
Graph 5 There was a significant difference seen in parameters E line
to Ls, E line to Li, S line to Ls, S line to Li, Inf sulcus- H line.
24
Graph 9 There was no significant difference seen inthe frontal
parameters Upp lip length ,Lwr lip length ,CPh-Li (R) and CPh- Li
(L) )
DISCUSSION
Pretreatment records are the basis of good orthodontic diagnosis.
Graph 10, 11 & 12 shows Pre to post treatment changes in
Frontal parameters assessed through Scans.
Clinical photographs have long been considered the gold
standard for orthodontic diagnosis.16 They are used not only to
record the pre-treatment and post-treatment extra oral and intra
oral clinical conditions, but also to keep a track of and record the
treatment progress.
The major drawback however of these photographs is that they
record the facial profile in a 2D manner. With advances in 3D
imaging technology, the orthodontists now have access to
overcome this disadvantage. As the soft tissue esthetics take a
center stage in seeking orthodontic treatment, the diagnostic
tools need to be more accurate and predictable.17 We used a
Graph 10 There was no significant difference seen in the frontal
structured light based scanner The Sense® by 3D systems for
parameters Inter-pupillary, Tri-G, N-Sn, Sn-Me.
scanning in our study. Lili Ma and Tianmin Xu in
200913validated a three-dimensional facial scanning system
based on structured light techniques and concluded that
treatment evaluation, growth and surgery planning can very well
be approached with these systems without any radiation hazards.
Adult patients with Class I bimaxillary malocclusion need
extractions of all first premolars and maximum retraction to
achieve an esthetic profile. The preoperative and postoperative
photographs and 3D scans of individual subjects taken prior to
Graph 11 There was no significant difference seen in the frontal
bonding and at the end of the treatment respectively in a
parameters Inter- commissural, Inter alar.
standardized manner were evaluated for ten frontal and twelve
lateral parameters before and after the treatment. The changes
observed by both modalities were then compared with each
other.
Soft tissue adaptation after orthodontic therapy shows a wide
range of variability and adaptability with respect to every
individual. Leonardi et al in 2010 18 in their systematic review
on soft tissue changes following the extraction of premolars in
non-growing patients with bimaxillary protrusion demonstrated
that upper and lower lips retract by 2-3.2 mm and 2-4.5 mm
Graph 12 There was no significant difference seen in the frontal
parameters Upp lip length, Lwr lip length, CPh-Li (R) and CPh- Li
respectively alongwith increase in nasolabial angle after
(L)
treatment with all first four pre molar extractions in biprotrusive
There was no significant difference seen in lateral and frontal
patients. Similar observations were made in our study also. The
parameters when
3D scans were compared with
2D
statistically significant reduction in the value of Ls and Li from
photographs using t test as p>0.05.
TVL, E line and S line indicates that there has been an overall
Journal of Contemporary Orthodontics, Oct-Dec 2020;4(4):21-28
25
Shukla et al
retraction in the position of upper and lower lip.
ultimately lead to more satisfied patients. The use of 3D scans
However, a statistical increase unlike our study was found by
when superimposed with other modalities like CBCT, can be a
Janson et al. in 201519 in distance of Ls and Li to S line,
boon to oral and maxillofacial surgeons and prosthetic surgeons
reporting it to be
0.2
± 2.79 mm and
1.2
± 2.8 mm
in predicting the exact facial response after their surgeries.23 A
respectively. The difference could be due to the variance in
range of customized extra oral appliances could therefore be
subjects as Class II patients were also considered in this study.
constructed to maximize their benefits with better adaptation to
Solem et al 20 reported that the soft tissue lip changes extend
facial anatomy and contours which cannot be done with
upto the columella area. Since soft tissues are known to
photographic records.
follow the underlying hard tissue structures, it can be inferred
As the technological advancements are taking place, it has
that soft tissue changes observed in our study at Sn and
become imperative that the diagnostic tools are upgraded so that
inferior sulcus depth might be the result of the same.
better treatment results can be achieved. On one hand we have
The increase in nasolabial angle and Merrifield Z angle with a
the long trusted photographic records which do not give us a
decrease in H angle can be attributed to the retraction of the
complete picture of soft tissue esthetics in all the three planes of
upper and lower lips concurrent with backward movement of
dimension. There are certain problems of standardization
Sn and forward movement of the Pog.
associated with them that makes their use for post treatment and
From the above mentioned findings we can see that the
pre-treatment comparisons questionable and for appliance
changes observed in the photographic evaluation and
customizations not suitable. Whereas on the other hand we have
evaluation through scans were very similar and statistically
3D Scanning systems available which are technologically
non-significant. This means that the analysis through scans is
advanced and far superior to conventional photographs. They
as reliable as that of the photographs.
help in studying the face from all aspects, with accurate
As for the frontal parameters, none of the readings were
replication and precision landmark identification. They also open
statistically significant indicating that in adult patients with
doors for advent of newer treatment procedures and devices
bimaxillary protrusion treated with all first four premolar
which are more effective, efficient, predictable and accurate and
extraction with maximum retraction, the changes seen in
less uncertain.
profile are more in antero-posterior dimension. There is no
The findings in the study have clearly indicated the reliability
change in vertical or transverse dimension of the facial soft
and efficacy of
3D scans in clinical orthodontics. The
tissue.
aforementioned advantages of
3D over conventional
When the frontal parameters such as inter-pupillary distance,
photographs further emphasize the need to adopt this trending
inter-alar width and inter-commisural length was clinically
technology and use it to expand the quality of orthodontic
evaluated with the subject it was found that the measurements
diagnosis and treatment.
from the scans were closer to the ones obtained on subjects.
CONCLUSION
The accuracy level which is claimed by the sense company
i.e. 0.060 mm21 is, therefore, clinically reliable.
From the present study it can be seen that:
3D imaging was born in 1970s and has ever since evolved for
Soft tissue profile changes from pre-treatment to post-
craniofacial growth analysis and facial morphology recording.
treatment in all first four premolar extraction bimaxillary
In 2013, Kazu Hayashi and others22 concluded that clinically
protrusion cases are majorly seen in antero-posterior
reliable and accurate results are obtained with 3D systems.
direction.
The non-invasive
3D technology not only assists in pre-
There is significant reduction in upper and lower lip
treatment and post-treatment assessment of dento skeletal
protrusion and increase in nasolabial angle and flattening of
relationship and facial esthetics, but also enable us to plan our
the facial profile. Since all the subjects in this study were
treatment precisely, predict the changes more accurately, and
adults, such soft tissue changes can be attributed more to
26
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Nassef, Essam & Attia, Khaled & Al-Hadithiy, Saba &
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Mostafa, Yehya.
(2009). Soft tissue cephalometrics: an
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