Dental implant is an extensively used treatment approach to replace a missing or extracted tooth. Implant placement procedure is a delicate procedure which requires extensive skills and theoretical knowledge. Augmented reality is a computer-based simulation which creates a three-dimensional image or environment. The integration of augmented reality in planning and placing of dental implants revolutionize the patient care in a clinical scenario. The introduction of augmented and virtual reality in treatment planning, teaching and simulation software’s has opened avenues for better understanding, diagnosis and treatment which leads to better patient care and outcomes. This article provides an insight into the available virtual reality tools for dental implant placements, effectiveness, challenges and the future of these tools in oral implantology.
Key words: Augmented reality, Virtual reality, Digital navigation system, Oral implantology simulators
Modern prosthodontic practice has witnessed
a revolution from traditional methods to what is
practiced today, from conventional impressions
to a completely digitalized workflow. Digital
advancements like Computer aided designing
and Computer aided manufacturing have set new
horizons in simplifying the treatment procedures
in Prosthodontics. Replacement of missing tooth
with implants is a widely used treatment option
in fixed prosthodontics. Implant placement is
a delicate procedure which requires precise
planning and positioning. And the precise
three-dimensional positioning of implants in
maxillofacial region is quite challenging due
to the proximity to vital structures and complex
anatomy. But with the advent of 3D technologies
and advancements this has become lesser
challenging now. The most recent of them is
the reality–virtuality continuum augmented
reality and virtual reality. The integration of
reality-virtuality improves the clinical practice
by compiling real data with the digital data
obtained from the patient.
Virtual Reality (VR) is a computer-generated
simulation of a three-dimensional image or
environment which provides a standardized,
safe, and flexible platform that can be interacted
with in a seemingly real or physical way by a
person with special electronic equipment
consisting of sensors1. Augmented reality
(AR) involves an interactive technology which
is distinct from virtual reality in that the user
interacts with an integral image of the patient’s
teeth/anatomical structures and works on them in
a 3D environment registered using fundamental
imaging techniques, and thus AR enhances the
physical elements with virtual elements1. AR
and VR systems require real and virtual data
sources, tracking, registration, visualization
processing, perception locations, display types,
and feedback methods. Virtual reality forms a
virtual world where Augmented Reality builds
a link between the real and virtual worlds
which allows users to interact with both worlds
simultaneously.
Head-mounted displays (HMD), monocular
systems, monitor- based interfaces and
other combined technologies are the devices
commonly used in augmented reality systems.
The main application of AR system in dentistry
is that it overlays the digital data on to the real
world data like photos, videos and 3D models
and forms a live communication mode between
clinician and patient through photos, videos,
and 3D models2. AR guiding devices show real-time intraoperative data right on the operating
site, in contrast to image-guided surgery where
the doctor has to focus away from the surgical
field thereby minimizing the surgical risk. A 3D
model is created right in the patient’s mouth by
the augmented reality device. This allows for
3D Aesthetic planning of the prosthesis. An AR
system can also share the operators data with
the technician or with a specialist3.
But there is a steep learning curve associated with the successful integration of VR/AR guided
surgeries and the high cost of setting up may limit
the use for most clinics4
and the further benefits
of this technology has yet to be explored. This
article reviews various aspects of augmented
reality integrated implant placements which
may aid in future research and references.
The evolvement of Augmented Reality into
dentistry and oral implantology comes through
the development of various aspects of digital
technologies. The development of Digital dentistry
can be traced back to 1970s when computerized
tomography (CT) was introduced. With CT scans
a detailed and accurate imaging of teeth and
jaws is possible which provided an improved
diagnosis and treatment planning. The actual
digitalization came into dentistry in the form of
Computer aided Designing/ Computer Aided
Manufacturing (CAD/CAM). It was introduced in
1980s for dental restorations. It was through the
CAD/CAM designing and milling of restoration
was made possible and with the advent of
3D printers in 1990s digitalization advanced
rapidly. CEREC system can be considered as the
pioneers in the world of digital dentistry through
which digital imaging and CAD/CAM made it
possible to deliver prosthesis in single visit. In
the next few years digital technology advanced
rapidly. Various companies like 3Shape,
Dentsply Sirona, developed software, advanced
digital imaging and scanning technologies and
3D printers for virtual treatment planning and
simulation. Computer assisted procedures were
slowly integrated into various fields of dentistry.
Oral implantology witnessed a dramatic
progress from free handed surgeries to static
guided surgeries to navigated system controlled
surgeries.
The parallel advancements in radiographic imaging such as CBCT scans provided 3D
images of the teeth and jaw, which can be
used to plan the placement and positioning
of the implant and with the help of 3D printing
and CAD/CAM surgical templates were easily
manufactured for static guided surgeries.
Computerized navigation surgery evolved from
neurosurgical procedures into the field of oral
implantology. This technique allows the clinician
to precisely transfer a detailed presurgical
implant plan to the patient. The clinician uses
computerized navigation to adjust the position
and angulation of the surgical drill according
to the presurgical digital implant plan. The
real time imaging of the surgical drill allows
for continuous updates on the positioning of
the drill to avoid critical anatomic structures.
Dynamic navigation (DN) aids the surgeons by
providing a real-time navigation tool to improve
the accuracy of implant placement.
Although the navigation tool assists in better
implant positioning and drilling operations, they
do not provide the operator to grasp the feel of
bone drilling and surgeon has to frequently look
away from the surgical site on to the screen. It
was then virtual reality which enables us to feel
the sense of sight and touch integrated to the
oral implantology5. The advent of virtual reality
in oral implantology could bridge the short
comings and enables the surgeon to feel the
sense of sight and touch of implant placement.
The Anatomical Simulator (AS) and The Virtual
Simulator (VS) are passive simulators which
do not have any interaction with the operator.
Anatomical Virtual Simulator (AVS) and the
Virtual Simulator with Force Feedback (VSFF)
are active type of simulators. The phantom head
used in preclinical labs in dental training is a
type of anatomical simulator. The computer generated 3D images constitute the virtual
simulator which helps in better visualization and
planning and do not permit any interaction.
The anatomical virtual simulator includes the
incorporation of haptic interface, graphics and
acoustics making it an active simulator allowing
interaction with the operator. The virtual simulator
with force feedback possesses the same features
but it involves incorporation of force feedback.
Recent advancements in 3D technologies like
augmented reality and virtual reality has led
to successful applications in oral implantology.
An accurate positioning of dental implants is
inevitable for aesthetics and functions. The
integration of virtual and augmented reality
with preoperative CBCT is done to determine
the implant dimension, direction of implant
placement, position and proximity to vital
structures. 3D planning is done and the data
is transferred to the surgical site with the help
of static and dynamic guides. Various static
guiding systems based on CAD/CAM is available
including Easy Guide, GPIS, Impla 3D, In vivo
Dental, Implant 3D, Nobel Bioguide and VIP
(Implant Logic System). The dynamic system on
the other side allows real time feedback while
placing an implant.
Dynamic surgery has added advantages over
static guide as the laboratory procedures can
be eliminated and there is a live view of the
surgical field. Dynamic navigation provides
real-time monitoring of implant site preparation
during surgery. Recording of the dentition and
the reconstruction of the cone beam computed
tomography (CBCT) or computed tomography
(CT) data is carried out and the surgeon can
monitor the position of the surgical drills on the
CT reconstruction with the help of the specialized software and tracking methods to follow the
movement of the surgical instruments in surgical
site.
Marton Kivovics et al concluded from an invitro
study that implant positioning accuracy of AR-based dynamic CAIS was comparable to that
provided by static CAIS and superior to that
obtained using the free-hand approach6.
The first step in placing an implant with the
help of AR tool is to make a CBCT scan with
the markers plate from the navigation system.
These markers must be positioned in situ as per
protocol by using the navigation system and
for which the plates should be fixed with a hard
impression material7. After the scan, the markers
plate has to be removed and replaced in the
same position on the day of the surgery.
The CBCT data has to be analysed through the
navigation system planning software and the
position of implant has to be virtually planned.
At the time of the surgery the patient reference
tool for the navigation system has to be fixed
on the same support of the markers plate.
Another reference tool has to be positioned and
rigidly fixed on the implant drill handle. Then
the calibration tool is connected to the handle
and the drill axis is identified by the navigation
system. The first lance drill is successively used
to touch the fiducial markers on the markers
plate to verify the patient position.
AR systems can be of four types. TYPE I - Involving
the use of glasses or head-sets, TYPE II - Digital
data being projected on a half-silvered mirror,
TYPE III - Images are shown directly onto the
patients, TYPE IV - With the use of an external
monitor1.
In systems using glasses after the calibration
procedures, the navigation system has to be directly interfaced with the virtual reality glasses
through a WIFI connection using a dedicated
software8. In systems using glasses, the surgeon
can contemporarily visualize the surgical field
and the output of the navigation system screen.
The virtual position and the trajectory of the drill
into the bone, the implant planned position and
the bone anatomy around the implant site can
be checked in real-time throughout the whole
surgical procedure.
The advantages of AR systems can be out
listed as in Preoperative planning1: It helps to
provide realistic outcome predictions based on
a precise pre-operative planning. Intraoperative
navigation helps surgeon with improved results
and for avoiding potential risks. With the help of
AR system a number of clinical scenarios and
treatment requirements can be created which
will help to evaluate the possible errors that occur
in clinical conditions and enables the surgeon
prepare for it better. During implant surgery AR
systems combine real and virtual worlds and the
real time interaction and a precise 3D registration
of real and virtual objects with superimposing of
CBCT on the surgical site enables the clinician
to understand the bone morphology better7.
In implant placement procedures AR systems
can filter out the information and display only
the relevant data to clinician thereby helping
them to concentrate on the implant placement
procedures reducing the risk and improving the
outcomes9. Integrating the surgical template with
the AR system in implant procedures significantly
reduced placement deviation6. Learning and
planning through virtual and augmented reality
aids lay out prodigious data, tracking of the
hand movements of the operator and finest
level of accuracy for evaluation10. The learning
systems can be programmed with a feedback
loops to warn the students against any minute
mistakes. As an educational tool, AR simulators
provide enhanced opportunities to students and
medical residents11.
Various challenges involved in AR system
includes:
There is often a discrepancy between the real
image and the virtual image due to an overlay
or positional error12. As with any technology
a steep learning curve exists for using AR/VR
system. Setting up a clinic with AR/VR system
which is an ever changing technology can be
expensive in terms of money and time. Building
up the content for a VR/AR system can be difficult
and may necessitate the help of an engineer
or technical expert. As with all digital system
digital platform, AR/VR software are also prone
to bugs which can lead to interruption in the
transmission of data13.
Other technologies can be integrated to enhance
the current AR systems like Photon emission
tomography, near infra-red spectroscopy and
the use of dyes, such as indocyanine to identify
complex anatomy and vital structures14. Haptic
force feedback and robotics are also promising
avenues to combine with AR technology7.
However further in vivo clinical trials has to be
conducted to investigate the clinical accuracy
and treatment quality of the proposed system
in the future. Future studies should be based
on virtual variation simulation of CAD/CAM
template combined with AR-based guided
surgeries on actual patients to reveal surgical
system limitations and errors as well as to gain
more experience to minimize the geometric
variation.
The integration of advanced technologies based
on 3D evaluation of the patient and computer
guided surgeries in oral implantology provides
better understanding, precise diagnosis and
successful prosthodontic rehabilitation of
patients. The giant leaps in the technological advancements may soon give rise to computer
and robotics assisted surgeries which may
become a routine in planning and positioning
implants. Thorough pre-operative planning and
surgical simulation with the help of AR system
provides a new learning experience and a
paradigm shift in enhancing psychomotor skills.