Review Article

ENDODONTOLOGY

Haptic-based virtual reality dental simulator as an educational tool JAYAPRAKASH PATIL *# NIKHIL SARAN **# ROSHAN SHETTY ***##

ABSTRACT The availability of datasets comprising of digitized images of human body cross sections as well as images acquired with other modalities such as CT and MRI, along with the recent advances in fields like graphics, 3D visualization, virtual reality, 2D and 3D image processing and analysis (segmentation, registration, filtering, etc.) have given rise to a broad range of educational, diagnostic and treatment planning applications, such as virtual anatomy and digital atlases, virtual endoscopy, intervention planning etc. This article presents the insight into the present state of virtual reality technology in dental training and treatment. Key Terms: Dental Simulator, Haptic Device, Haptic Recording and Playback, Haptic rendering, Haptics, Virtual Reality.

INTRODUCTION

phenomena and the laws that rule them.

Over the last decade there has been a marked

Dentistry is one such field where diversity and

increase in the use of technology in medical

complexity in anatomical structure in the operating

education1,2. Concomitantly, dental education has

field makes it almost impossible to learn and plan

also seen an increased use of technology in both

treatment as a rule or as presented in texts. Haptic

learning and training. Routinely, dental students

Applications allow operator to interact with the

obtain their skills training from various sources. The

sense of touch, along with visual and acoustic

traditional one relies on practicing procedural skills

representations of objects and scenes. A Haptic

on plastic teeth or sometimes live patients under

Application requires a Haptic Interface Device

supervision of dental experts. However, it is being

through which the user interacts with the

challenged because of complications in surgery,

application. Many such models available in

increasing cost of training materials, the ethical

international market provide realistic 3D models

concerns for safety of patients, and the

with features like

unavailability of many real-world challenging cases. Apart from that, during learning procedures, it

1. Haptic sensing,

appears that there is a difficulty in understanding

2. Replay and recording ability,

certain aspects of the physic world without the actual sense of it, because vision and hearing is

3. Unlimited practice time, and

required in order to fully perceive the physic * Prof. & HOD, ** PG student, *** Reader, # Department of Conservative Dentistry and Endodontics, Sri Sai College of Dental surgery, Vikarabad, (A.P.), ## Department of Public Health Dentistry, A. J. Institute Dental Sciences, Mangalore.

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4. Ability to share recordings of the procedures

remote environments since the robotic arm is able

online.

to provide preprogrammed guidance.

supplement to traditional teaching methods to

VIRTUAL DENTAL PATIENT (VDP) AND SIMULATOR COMPONENTS

improve skills and challenges associated with

There are multiple companies in market which

treatment procedures and for better understanding

provide various virtual simulators specifically for

and decision making in treatment plan.

medical and dental use. These systems comprise

These features combine to make it an ideal

combination of hardware and software which in

THE CONCEPTUAL IDEA BEHIND HAPTICS

integrity works as a VDP. The simulator system consists of a high-end computer workstation with

Touch is one of the most fundamental ways

appropriate software, a haptic device, and a

for people to perceive physical objects 3, until

stereoscopic computer monitor with stereo glasses.

recently VR simulators focused primarily on the

The computer renders three-dimensional (3D)

audio and visual aspects of simulation4. However,

graphics that can be viewed with the stereo glasses,

to explore an object of interest we would like to be

and operates the haptic device that provides a

able to sense its physical properties by applying

realistic tactile sensation. Onscreen VR instruments

forces to it5-7. This is possible by using special

can be manipulated on this monitor by operating

mechanical tools, called haptic devices that enable

the haptic device stylus for sensing life-like contact

the user to feel the feedback forces 8. Recent

and interaction with teeth and associated anatomic

technological advances have resulted in the

structures.

production of a variety of affordable haptic devices, such as PHANToM™ Desktop 9 , providing possibilities for creating sophisticated simulation systems with vastly improved touch-based humanmachine interfaces. Haptics allow the user to feel, manipulate and interact with the object displayed on the PC monitor. The user can touch, move and feel an existing distant object indirectly through a robotic arm. Furthermore, haptics provide force feedback to humans interacting with virtual or

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HAPTIC-BASED VIRTUAL REALITY DENTAL SIMULATOR AS AN EDUCATIONAL TOOL

SO THE FOUR MAJOR ASPECT OF VDP ARE:



A motion-tracking camera. A typical digital

camera is attached to the 3D monitor. The camera

1. Physical setup – includes dental tools to be

tracks a marker placed on the spectacles.

used, mounting of monitors, workspace size similar

SIMULATOR FUNCTIONALITY

to that of a mouth, a device for users’ fingers to rest

The simulator consists of several functional

on, and so on.

blocks realized in its software. These include model

2. Graphic screen display – includes ‘near-

selection, graphics and haptics control as well as

realistic’ image of an oral cavity, graphic dental

record and replay functionality. They are necessary

tools, motion representations of hand and dental

for the complete functionality and agility in the oral

tools matching those in the physical setup, different

work environment, e.g. It is well documented that

angular views of an oral cavity relative to users and

the force of around 20 gf (0.196 N) is all that is

patients’ position.

required for periodontal probing10,11. However, it

3. Multi-sensory feedback – includes modeling

is difficult, if not impossible, to describe to a student

of sound effects, tactile feedback, and color change

how much force this is. With the use of a haptic

when drilling at different pressure and speed of a

device, the exact force reading can be viewed and

dental tool, and when cutting different parts of a

felt by instructor and student, thus greatly enhancing

tooth.

the learning experience.

1. INSTRUMENT SELECTION

4. Data sources for modeling requirements –

Currently there are over 10 dental instruments

includes sources of actual ‘data’ to produce 3D

which may be chosen for haptic use, new

representation of the oral cavity and tooth (i.e. CT

instruments, and models can be added easily when

scans, discarded bones of teeth and jaw).

desired.

The first working prototype for the dental

2. GRAPHICS CONTROL

specification has following component in particular

In the main window of the simulator the user

and was marketed with the name of PHANToM™

can see the full-screen 3D model of area of interest

Desktop (SensAble Technologies, Woburn, MA,

in a dental arch along with the main control panel.

USA).

The main control panel (Figure.3) contains a variety A haptic device. This includes an actual

of controls for navigation which include options to

dental headpiece. The position and orientation are

select and manipulate gingiva, teeth, bone and any

matched to the graphic headpiece displayed on the

other model objects. The operator can induce

monitor.

varying degrees of transparency of the selected



objects using a slider bar.

 A 3D stereoscopic display monitor. The user

wears spectacles with polarized lenses. To produce the optical illusion of 3D perception, different visual signals are sent to the eyes.

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JAYAPRAKASH PATIL, NIKHIL SARAN , ROSHAN SHETTY

Figure 4. Haptic control panel

4. RECORD AND REPLAY FUNCTIONALITY An important functionality in the simulator is 3D haptic recording and playback capability allowing the user to record the motion of an instrument for certain time, such as cavity preparation, which can be stored and played back on the computer in future, either from storage media or over the Internet14. The recorded 3D motion can be played back in one of the three modes15 A. Observation mode B. Learning mode C. Testing mode

FUTURE OF HAPTIC SYSTEMS AND ITS APPLICATION

Figure.3 Main control panel

In an reality assessment experiment, thirty experienced dental and hygiene instructors from a variety of clinical areas were then used to assess

3. HAPTICS CONTROL In the main window of the simulator the user

the realism of this system and determine which

can control the haptic properties of the simulation

components required further development16,17.

process. This includes the basic ability to turn

Faculty / practitioners found the images very

haptics on or off for each selected object. The haptic

realistic for teeth and instruments, but less so for

parameter like Viscosity, Stiffness, Static friction,

gingiva. Tactile sensation was realistic for teeth

Dynamic friction12,13 can be controlled and be

but not so for gingiva. This gives a space for further

altered separately for each object (Figure 4).

development of the device. Present haptic systems 117

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HAPTIC-BASED VIRTUAL REALITY DENTAL SIMULATOR AS AN EDUCATIONAL TOOL

References:-

although fulfills most of the working criteria but

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CONCLUSION The growing use of computers, networking,

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mean of training and not a replacement for the

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perception of content validity of PerioSim, a haptic-3D virtual reality dental training simulator. Journal of Dental Education, 17, 1574–1582.

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