Int. J. Morphol.

,
33(2):782-787, 2015.

Generation of 3D Tooth Models Based on Three-dimensional

Scanning to Study the Morphology of Permanent Teeth

Generación de Modelos de diente 3D Basados en Escaneo Tridimensional

para el Estudio Morfológico de Dientes Permanentes

Mario Cantín*,**; M. Muñoz***,**** & Sergio Olate*,*****

CANTÍN, M.; MUÑOZ, M. & OLATE, S. Generation of 3D tooth models based on three-dimensional scanning to study the morphology
of permanent teeth. Int. J. Morphol., 33(2):782-787, 2015.

SUMMARY: The dental student should have thorough knowledge of the dental morphology and develop adequate manual skill
to reproduce any part of the tooth, thus maintaining the perfect correlation with associated structures. Computers are becoming an
integral part of dental education and dental practice, especially for the acquisition of information in three dimensions and the production
of solid objects from computer models. The aim was to present educational material that would allow the dental student to learn to easily
identify the morphologic characteristics of permanent teeth, using new technological tools. In order to do this, healthy permanent teeth
were scanning by NextEngine™ 3D Scanner HD using the MultiDrive. A 360° scan in macro range was chosen in each case. The number
of scans for this family was 16, due to surface irregularities that require readings from a greater number of angles. Volumes of external
structures of the scanned tooth were generated and stored in *.STL files. Virtual models were transferred in to programs used for
producing physical prototypes that faithfully reproduce anatomy of interest using ReplicatorG software and MBot Grid II 3D printer. 3D
virtual and printed macro models of permanent teeth were obtained. This models allows an excellent visualization of the morphological
characteristics of permanent teeth. 3D virtual and printed teeth, derived from real tooth, are intended to be a valuable learning tool that
can be used in addition to or instead of extracted teeth and they are anticipated to represent an improvement over plastic teeth.

KEY WORDS: Dental morphology; Permanent teeth; Dental education; 3D scanning; 3D printing; Macro models.

INTRODUCTION

The knowledge of dental anatomy is fundamental for The external anatomy of teeth should be very well
the practice of any branch of dentistry and form an important known. Theoretical studies are not enough. The student
part of dental schools' curricula. Although anatomy, in ge- should study the detailed description of the tooth with co-
neral, seems to be a descriptive and static science, dental pies of them in their hands, and the use of macro models
anatomy escapes from this rule, because it needs to explain facilitate the assimilation or re-memorization of anatomy
the reason for the existence of dynamic functions of the teeth because they show all anatomical details that need to be
(Siéssere et al., 2004). reproduced (Siéssere et al.).

The use of extracted human teeth in dental education The introduction and development of 3D software,
remains the optimal basis for the clinical training of dental scanning and print techniques enable the visualization and
students in many aspects. However, the difficulties in creation of virtual and real anatomical models which give
accessing a sufficient number of suitable extracted teeth for students the opportunity to learn anatomy in detail and train
all students, issues with hygiene and the ethical questions for dental procedures as many times as necessary (Friedland
involved in using human material for educational purposes et al., 2008). Additionally, with on-going developments in
without written consent make (de Boer et al., 2013), which technology and the increasing availability and use of
is an obstacle to understanding the anatomy. computer products such as smartphones, tablets and e-books,

*
CIMA Research Group, Faculty of Dentistry, Universidad de La Frontera, Temuco, Chile.
**
Doctoral Program in Morphological Sciences, CEMyQ, Faculty of Medicine, Universidad de La Frontera, Temuco, Chile.
***
Fellow Researcher, Universidad Científica del Sur, Lima, Perú.
****
Center of Research in Biomedical Sciences, Universidad Autónoma de Chile, Temuco, Chile.
*****
Division of Oral and Maxillofacial Surgery and CEMyQ, Faculty of Dentistry, Universidad de La Frontera, Temuco, Chile.

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 CANTÍN, M.; MUÑOZ, M. & OLATE, S. Generation of 3D tooth models based on three-dimensional scanning to study the morphology of permanent teeth. Int. J. Morphol., 33(2):782-787, 2015.

contemporary students are well acquainted with the use of requirements, but not to the resolution of the model. This
computer technology in everyday life (de Boer et al., 2015). device generated all outer contours of the tooth for each stroke
and from these surfaces, volumes of external structures of
The aim was to present educational material that the scanned tooth were generated and stored in *.STL files.
would allow the dental student to learn to easily identify the The scans in each family were aligned and fused; this merged
morphologic characteristics of permanent teeth, using new the scans into one solid mesh.
technological tools.
Once the virtual models were generated, they were
transferred in to programs used for prototyping by producing
MATERIAL AND METHOD physical prototypes that faithfully reproduce anatomy of
interest. ReplicatorG is an easy-to-use software in which you
can load up 3D designs of the STL format. The program allows
The specimen were permanent maxillary and to do the following: position, scale and rotate the part, and to
mandibullary tooth extracted from Chilean individuals. A convert it into printing instructions (called GCode) and printed
complete dental set was obtained. The specimen had no tooth in a machine MBot Grid II 3D.
substance defects or caries. The present study was approved
by the Ethics Committee of Universidad de La Frontera (no.
024/15). RESULTS

The healthy tooth were selected to serve as standard

to the generation of virtual models and prototypes. The procedure described above offers many
Subsequently, a tooth was placed in a contact scanner possibilities for the creation and editing of virtual teeth to be
NextEngine™ 3D Scanner HD (NextEngine, Inc., CA, USA) used in a virtual learning environment for dental education.
and ScanStudio HD Pro® software, using the MultiDrive
hardware, that allows for an object to be rotated around the The creation of a virtual tooth begins by scanning an
vertical axis and at different tilts to the vertical axis. This extracted tooth was successfully. The ScanStudio HD Pro®
allows for an object to be completely scanned in one scanset. software uses segmentation algorithms to obtain a 3D
This hardware has an advantage of automatically scanning visualization. A 3D tooth model was successfully developed
several scansets without the need to manually reposition the and converted to a versatile format using various applications
object. (Fig. 1).

The NextEngine scanner, calibrated at the appropriate In particular, the properties of general shape and colours
resolution, produces high quality surface scans with clearly of the virtual teeth were considered very similar to those of
detectable detail. Each generated virtual surface represents a the extracted teeth.
“mesh”, composed of hundreds of thousands of triangles
drawn between hundreds of thousands of 3D coordinates. A The faithful reproduction of the the buccal, lingual,
built-in digital camera captures images of the object, which palatal, mesial and distal tooth surfaces were achieved in the
are mapped onto the mesh, resulting in a texture rendering of virtual model. Furthermore, it could scan the entire root outline,
the model. Finished models were created using the ScanStudio including the angles of aplical end. In cases of complex root
HD software by placing virtual beads on the same spot in anatomy, multiradicular teeth, anatomy of each root and
two different scan views. interradicular furcal area it was rebuilt (Fig. 2). In a particular
case, the mandibular first molar with caries in the buccal
The scanner mode was set to a resolution of 10,000 groove, reconstruction allowed to maintain the shape of the
points per square inch (associated accuracy=?0.005 inches), pit.
while surface texture was recorded as either grayscale or RBG
color information with a resolution of 150 dots per inch. Comparing the surfaces of the teeth, including the
occlusal surface in molars and premolars, the virtual model
For each tooth, the chosen scanning protocol was 360° representing all the details of each tooth. The occlusal surface
scan (complete revolution of the rotating platform) in macro could show all the anatomical details of cusps, grooves and
range (3" x 5" field of view). The number of divisions, or pits, reproducing exactly the original anatomy.
number of scans for this family was 16, due to surface
irregularities that require readings from a greater number of Each generated virtual tooth could be printed as a
angles. This adds to the scanning time and storage macro model, increased its volume threefold (Fig. 3).
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CANTÍN, M.; MUÑOZ, M. & OLATE, S. Generation of 3D tooth models based on three-dimensional scanning to study the morphology of permanent teeth. Int. J. Morphol., 33(2):782-787, 2015.

Fig. 1. Single-rooted tooth three-dimensional model. A. Healty canine tooth for scanning. B. ScanStudio HD Pro®
representation after smoothing of the data set obtained from the canine tooth. C. Virtual 3D model with different views:
lingual, buccal, distal, incisal and apical.

Fig. 2. Multi-rooted tooth three-dimensional model. A. Healty mandibullary first molar tooth for scanning. B. ScanStudio
HD Pro® representation after smoothing of the data set obtained from the canine tooth. C. Virtual 3D model with different
views by ReplicatorG software prior to GCode generation.

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Macro models allow a better visualization of the morphologic

characteristics of permanent teeth and students of dental
anatomy (Siéssere et al.)

Dental educators are responsible for providing the

requisite psychomotor training to students during their
preclinical education. Innovative strategies are needed to
facilitate learning and motivate students’ interest, as well as
to help them visualize the tooth anatomy. Though currently
the use of computers and computer assisted graphics have
helped out in teaching dental anatomy in the three dimensio-
nal views, drawing and dental carving are considered to be
very practical and objetive methods for teaching and
motivating dental students to obtain the knowledge till today.
Traditional classes suffer with the lack of possibilities for
interaction, as they do not develop manual skills (Kataoka et
al., 2005). Furthermore, several teaching institutions, with the
purpose of developing psychomotor skills, have associated
these classes with the activity of recognizing and reproducing
dental morphology by examining samples of preserved teeth
combined with the dental sculpture from wax blocks
(Brueckner & MacPherson, 2004; Siéssere et al.). With the
purpose to achieve better understanding and visualization of
dental morphology, macromodels are tools that have been
proved to be efficient, both in this study and in others, as they
are instruments that provide accurate anatomy (Buchaim et
Fig. 3. Printed 3D macro models of a upper premolar tooth al., 2014).
according to the scanning dataset.
With advances in three-dimensional (3D) measurement
devices, geometric data can be obtained more rapidly. Analysis
DISCUSSION of morphology based on 3D information is efficient, as it
enables morphometric evaluation of internal and external
structure without sample destruction (Hannig et al., 2006, Kato
The study of dental morphology is a basic and essentials & Ohno).
theme in dental science, a component of the basic sciences in
the program of Dentistry Schools and introduces students to The main advantage of virtual models is the facility of
the morphological characteristics of primary and permanent manipulation to change geometry by the software. It also
human dentition. It is very important for clinicians to allows rotation, fade in/fade out, cursor movements that reveal
understand dental form and internal structure in three structures, etc. The versatility of these virtual models allows
dimensions. Various aspects of tooth geometry and size have data exportation in other extension type, which enables
been investigated for tooth forms (Kato & Ohno, 2009). communication with numerical simulation software, e.g., finite
element analysis (Prado et al., 2013; Freire et al., 2014; Rossi
The external anatomy of teeth should be very well et al., 2014) and biomechanical analysis (Soares et al., 2013).
known. Theoretical studies are not enough. The student should Thus, it can also be used in several classes at a dental school
study the detailed description of the tooth with copies of them such as dental anatomy. The development of alternative
in their hands. Besides the study of extracted natural teeth, methods, such as computer-graphics, to aid in teaching three-
macro models made of plaster or resins and dental arch models dimensional dental anatomy and Tooth Morphology, which is
help to understand the aspects that must be taught. Macro a computer-assisted learning program designed to teach the
models facilitate the assimilation or re- memorization of anatomy of the adult dentition are important for motivating
anatomy because they show all anatomical details that need and teaching students. The Tooth Morphology program, in
to be reproduced. In this way, the student who practices den- combination with interactive class meetings, has replaced
tal carving exercises is able to develop normal anatomical form traditional dental anatomy lectures; however, it does not
of teeth, rees tablishing the function of the dental element. replace the practice of dental sculpting (Siéssere et al.).
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 CANTÍN, M.; MUÑOZ, M. & OLATE, S. Generation of 3D tooth models based on three-dimensional scanning to study the morphology of permanent teeth. Int. J. Morphol., 33(2):782-787, 2015.

Rapid prototyping (RP) is an expression that and the cost is about $20 each. Using this system, it is easy
represents a technology based on the construction of physical to create teaching blocks with a variety of type and number
three-dimensional structures, layer by layer, based on its of cavities, their sizes, and their positions. These models are
respective virtual models (Soares et al., 2012). RP has used in preclinical dental education for the development of
become an innovative method of fast and cost-effective student's visual recognition skills and fine eye-hand
production of three-dimensional models for manufacturing. coordination. The authors found that the students could grasp
Wide access to advanced medical imaging methods allows the concepts of different types of cavity preparation more
application of this technique for dental training purposes. easily with this model in their hands during exercises and
Four leading technologies are used for rapid prototyping they could start to communicate and express themselves in
(RP): stereoiithography, selective laser sintering (SLS), fused terms of evaluations of the cavity preparations at an earlier
deposition modelling (FDM), and three-dimensional (3D) time in the preclinical technique (Torres et al.).
printing (Torres et al., 2011). Digitally prepared 3D objects
are sent to the 3D printer like in an ordinary ink-jet desktop The development of RP systems has led to the
printer. The concept of printing is similar to that of a regular creation of customized three-dimensional anatomic models
printer; The 3D printer can use various materials: high- per- that exhibit a level of complexity unknown, primarily
formance composites are used to produce tough, strong, because RP methodologies use an additive process of buil-
coloured, and best resolution models; elastomeric materials ding an object in layers defined by a computer model that
which give rubber-like properties or casting material which has been virtually sliced (Nayar et al., 2015).
enables the creation of metal prototypes. 3D printers are
characterised by their excellent speed: a hand-held part is A disadvantage to visualize the data acquired and
produced within two or less hours (Torres et al.). processed to 3D reconstruction, is that a 3D software and
adequate hardware is required. But with 3D printing, all these
After being introduced in the biomedical area, complications disappear, and the generation of 3D models
computer-directed rapid prototyping techniques have been can be applied in any institution, without the need to mount
used for dental therapy, mainly for the fabrication of models a computer lab or have digital equipment so that all students
to ease surgical planning and in implantology, orthodontics, can use.
and maxillofacial prostheses (Pozzer et al., 2013). Rapid
prototyping technique can be also applied in another fields It is important to continue searching for alternative
in undergraduate dental education. Chan et al. (2004) using and integrative teaching techniques, which allow for
mechanical computer-aided design systems and developing both basic and professional sciences. Virtual and
stereolithography machines, a geometric model of a teaching printed teeth are intended to be a valuable learning tool that
cube with tooth cavities was constructed. The authors can be used in addition to or instead of extracted teeth and
conclude that the advantages of stereolithography are due they are anticipated to represent an improvement over plastic
to the capability of building complex geometrical accuracy teeth. The association of RP models with 3D- virtual models
and good surface finish. In this presented case of a teaching is a viable and accessible technique that helps and enriches
cube (2.54 cm3), the production time is usually thirty minutes the teaching-learning process.
CANTÍN, M.; MUÑOZ, M. & OLATE, S. Generación de modelos de diente 3D basados en escaneo tridimensional para el estudio morfológico
de dientes permanentes. Int. J. Morphol., 33(2):782-787, 2015.

RESUMEN: El estudiante de odontología debe tener un conocimiento profundo de la morfología dental y desarrollar la habilidad manual
adecuada para reproducir cualquier parte del diente, manteniendo así la correlación perfecta con las estructuras asociadas. La tecnología se está
convirtiendo en una parte integral de la educación y la práctica dental, especialmente por la generación de información en tres dimensiones y la
producción de objetos sólidos a partir de modelos computadorizados. El objetivo fue desarrollar material educativo que permita al estudiante de
odontología aprender a identificar fácilmente las características morfológicas de los dientes permanentes, utilizando las nuevas herramientas
tecnológicas. Dientes permanentes sanos maxilares y mandibulares fueron digitalizados utilizando un escáner 3D HD NextEngine™ mediante
sistemática MultiDrive. Una exploración de 360° en rango macro fue elegido en cada caso. El número de escaneos para cada diente de 16, debido
al nivel de detalle e irregularidades de las superficies dentarias que requieren lecturas de un mayor número de ángulos. Los volúmenes externos de
los dientes escaneados fueron generados y almacenados en archivos *.STL. Las reconstrucciones generadas fueron transferidas para la producción
de prototipos físicos que reproducen fielmente la anatomía de interés utilizando el programa ReplicatorG y la impresora Mbot Grid II 3D. Se
obtuvieron modelos virtuales 3D y macro modelos impresoss en 3D de los dientes permanentes. Estos modelos permiten una excelente visualiza-
ción de las características morfológicas. Los modelos dentarios virtuales e impresos en 3D, derivados de un diente real, son una valiosa herramien-
ta de aprendizaje que se puede utilizar además de o en lugar de dientes extraídos, y representan una mejora anatómica sobre los modelos de dientes
plásticos utilizados actualmente.

PALABRAS CLAVE: Morfología dental; Diente permanente; Educación dental; Escaneo 3D; Impresión 3D; Macro modelos.

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