Studies on the masticatory system have been conducted for decades, but so far, these studies have only recorded fixed locations or isolated mandibular positions (e.g., protrusion, excursion, etc.). The mandible is the primary moving part of the masticatory system.

1. Dr. Fatma Mahanna

2. • The masticatory system
is a functional unit
composed of the teeth;
their supporting
structures, the jaws; the
temporomandibular
joints; the muscles
involved directly or
indirectly in mastication
(including the muscles
of the lips and tongue);
and the vascular and
nervous systems
supplying these tissues.

3. • This system has been analyzed for many years, but
the methods used record statistic points or single
positions of the mandible (e.g., protrusion,
excursion, etc.). The masticatory system is, however,
dynamic, and the main component lies in the
mandible.
• Developments in digital dentistry have resulted in
mechanical articulators that simulate mandibular
movements being replaced and/or supplemented
with virtual articulators in dental computer-aided
design/computer-aided manufacturing
(CAD/CAM) systems

4. In contrast to conventional mechanical procedures, the virtual
articulator enables the visualization of three-dimensional (3D)
calculated jaw movements for specific TMJ parameters or based
on patient-specific dynamic motion data obtained using special
devices.
The main indications for the VA that have been proposed include
individualized diagnostics and avoidance of the common
problems encountered with MAs, such as creation of new occlusal
contacts, material deformation, errors during orientation and
positioning of dental casts, and difficulties simulating patient data in
three dimensions (3D).

5. Types of Virtual articulator:
There are currently two major types of VAs:
1. Completely adjustable (CA)
2. Mathematically simulated (MS).
Completely adjustable (CA) Mathematically simulated (MS).
The CA type reproduces exact movement
paths of the mandible
through the use of digital device accessories.
Indication: involves complex cases where the
morphology of the occlusal plane needs to be
assessed during mandibular movements to
avoid interferences in excursions.
In order to capture the dynamic elements of
occlusion and masticatory function, it was
necessary to use a specific device called
a Jaw Motion Analyzer (JMA)
The MS type is an average value articulator
which requires adjustment of additional
settings in order to reproduce mandibular
movements.
Indication: involves cases where reproducing
the relationship between the arches is
sufficient for planning the occlusal
morphology of the prosthesis.
Disadvantage:
• Couldn’t obtain individualized movements
• must repeat the procedures for using a
mechanical articulator, such as making
impressions, performing facebow transfer,
obtaining interocclusal records, and
mounting dental casts (limitation)

6. ❑ Based on the chosen method of data acquisition and
transfer, techniques for assembling a VA can be classified
as :
direct or indirect workflows.
- The first step in a direct workflow involves digital scanning
of the arches by means of an intraoral scanner (IOS), and
then subsequently transferring this data to the VA without
the use of analogue steps.
- The indirect workflow involves taking analogue impressions
of the arches, digitally scanning the casts mounted in a MA
by means of a desktop laboratory scanner (DLS), and then
transferring this data to the VA.

7. Lepidi et al, 2020

8. Importance of registration
of jaw movements

9. Understanding of mandibular movement(electromyography
coupled with jaw -tracking devices has provided much more
information of the correlation between jaw movements and
muscle activity) was considered important in:
1. This information was used in the design and setting of
articulators.
2. The design of the dentures and denture teeth .
3. Importance of jaw movements has become apparent in fixed
prosthodontics,( maintain and replace missing teeth should be
to provide patients with good masticatory
abilities)periodontics, orthodontics.
4. The diagnosis and treatment of disorders of the masticatory
system .
5. Follow up after treatment of TMJ disorders

10. Review of Jaw Tracking methods:
The extent to which jaw tracking provides a useful
research tool, a diagnostic aid, or a therapeutic monitor
clearly depends on what is being measured, how the
process is carried out, and why the information is
important To better understand differences between
various systems to record mandibular motion a review of
some recording methods presented over the years was
made.

11. 1. Methods Using Mechanical Devices (Graphical)
2. Photographic Methods
3. Roentgenographic Methods
4. Electronic And Telemetric Methods
5. Magnetometry
6. Opto-electronic Methods
7. Axiography
8. Cadiax Copmact
9. Computerized Analysis Of Mandibular Movements
10. Electromagnetic Articulography(EMA)
11. Computer-monitored Radionuclide Tracking

12. Axiography
Computerized Axiography
Axiography
By locating the condylar axis, the mandibular function can be
analysed in relation to both condylar hinge axis and occlusal
relationships.
Axiographic recording procedure includes the following:
• Clutch fixation
• Analyzer bow preparation and placement
• Placement of recording arm bow
• Hinge axis location
• Recording of movements

13. Cadiax Compact
• The Cadiax compact axiographic device was designed to produce a
fast joint analysis for articulator programming and also to aid in
diagnosing the functional mandibular disorders.
• It allows computerized recording of the opening, protrusion, and lateral
tracings, and it calculates the sagittal and transversal condylar
inclination angles for the adjustment of articulators

14. Electromagnetic Articulography (EMA)
• This device measures displacements
of the structure in real time as well as
the acoustics and mechanics of
speech using a microphone
connected to the measurement
system.
• It has transmitter coils that determine
magnetic fields to collect information
about movements from sensors
located on various structures (tongue,
palate, mouth, incisors, skin, etc.).
• After measurement, the information is
passed on to a computer and read to
visualize the recording of the
mandibular movements registered by
the EMA.

15. • Computer-monitored Radionuclide Tracking
• A three-dimensional recording of
mandibular movements .
• A small and harmless radioactive source is
fixed on the patient’s skin at the point of
interest or sealed in a tooth cavity.
• Using the proper collimation, the motion of
the point source is recorded through a
gamma camera and minicomputer.
• Long-term storage on a magnetic device
offers playback, slow-motion facilities, and
data analysis.

16. Radiograph and TMJ:
The hard and soft tissue structures of TMJ have been reconstructed
by spiral and helical CT and magnetic resonance imaging (MRI).
There are previous studies that have merged these data with jaw
movement recordings by ultrafast MRI, electromagnetic tracking
device, or optoelectric measuring systems.
(Terajima et al.,2008) (Baltali., 2008)

17. MRIs disadvantages are related to
1-The high cost
2-The need for the patient to lie down during MRI imaging,
which might alter normal jaw movements.
3-It is also contraindicated to patients with pacemakers and
metallic heart valves.
(Terajima et al.,2008) (Ferreira et al.,2016)

18. The disadvantage of the conventional CT is that it shows
higher exposure values than CBCT.
CBCTs main advantage is the observation of bony joint
structures in all three planes in addition to the possible image
manipulation at different depths and three-dimensional (3D)
reconstruction. (Ferreira et al.,2016)

19. C

20. C
MOTION
CAPTURE
SYSTEMS

22. Motion Capture System Using Infrared Cameras:
(Furtado et al.,2013)
Requirements:
• 3 infrared cameras
These cameras are natively capable to find out white points
in the images, which correspond to reflective objects
(usually markers) in the scene. All cameras synchronously
take images of the scene and reduce the image data to a set
of 2D image coordinate representing the detections of the
markers. Each camera is able to capture up to 100 frames per
second, which is sufficiently high to guarantee detailed
register of lower jaw movements.

23. • 9 Markers:
A set of nine retro-reflective markers is proposed to allow
mandibular movement analysis. Eight of them are called the
secondary tracking markers and their purpose includes estimating
some morphological parameters of the mandible.
The primary tracking marker is the one primarily employed to track
the movement of the jawbone.

24. Secondary tracking markers can be fixed on skin by using adhesive
tape and a plastic support.
They must be positioned on the following regions of the face:
(1) TMJ external surface (left and right)
(2) mandible angle region (left and right)
(3) middle region between the chin and the mandible angle (left and
right)
(4) above upper lip
(5) on the forehead.

25. • A prototype soft is implemented to communicate with the
cameras and perform:
2D point identification and tracking
3D data processing

27. Top view of the proposed camera setup. The left and right cameras are placed at 1 meter
distance from the subject forming an angle of 120 degrees. The central camera is positioned at
1.3 meters distance.

28. Advantages:
1- Good precision and accuracy
2- Minimum obstruction.
3- Real- time 3D reconstruction and analysis.
4- Moderate cost
5- It can give parameters of facial morphology and
automatically recognize markers.

30. Magnetic motion capture Jaw tracking system:
The jaw tracking system is based on the magnetic motion capture
system with wireless resonated marker.
The resonated markers are composed of an inductor and a capacitor,
neither electric wires nor batteries inside the marker are necessary.
Therefore, the markers can be easily attached to a tooth without
disturbing the physiology. The system can be used for highly
accurate jaw tracking without magnetic shielding because it is free of
earth field noise, thus making it superior to conventional jaw
movement tracking devices.

31. MOVEMENT
REGISTRATION SYSTEMS

32. • 1- MODJAW
• 2- ARCUS DIGMA
• 3- FREECORDER BlueFox
• 4- JMA Zebris
• 5- Planmeca 4D
• 6- SICAT JMT

33. Movement registration systems
1. MODJAW
• The MODJAW system uses optical scanning solution to dental surgeons
at the diagnostic and therapeutic stage.
• By simply capturing jaw motion, MODJAW models the kinematics of
patients.
• The software, designed with an ergonomic interface and touch-
screen diagnostic functionalities can provide dynamic visuals of
models in 2D and 4D, patient’s occlusion plans, dynamic mapping of
teeth contacts and automated calculation of posterior determinant
parameters (Bennett Angles, condylar slopes, Spee curve…).

35. • 2- ARCUS digma
• The ARCUS digma system uses
ultrasound transmission to measure and
reproduce the jaw movements.
• Arcus Digma systems consists of a
self-contained computer with a colour
touch screen (tabletop unit) or a two-
color screen (handheld), a head bow, a
pair of ultrasonic transmitter-sensors
that attach to the mandible with a small
device called a paraocclussial clutch
and to the maxilla with a bite fork.
• KaVo’s system is an articulator-
regulated registration technique and
requires the use of a KaVo PROTAR
articulator. During the measuring time,
this articulator is “virtually” projected
into the mouth of the patient.

36. 3- Freecorder BlueFox
• This contactless system tracks a series of encoded visual patterns. First, to
measure the position of the skull, a bow with references is placed on the
ears and then, it is attached to the nose’s bridge. Another light modular
arch is attached to the jaw to capture its movement.
• Using special cameras, them patterns are captured 100 times per
second, thus achieving very high resolutions (1/1000 mm.)

37. 4- JMA Zebris
• JMA Zebris system has a customized jaw’s anchor that joins the lower
arch by means of magnets.
• Another upper arch is placed on the skull and the nose’s bridge. Both
of them have electronic sensors that measure relative distances.
• The system determines the jaw’s relative position by calculating the
flight times of ultrasonic pulses.

38. 5- Planmeca 4D jaw motion
• The system tracks and visualizes jaw movements with the
Planmeca ProFace camera feature of Planmeca ProMax 3D
Mid and Max X-ray units, showing the movements in real-time
in a 3D CBCT image.
• The camera tracks the position and movement of eight
spheres. Half of them are fixed to a bow and the others to
glasses.
• Glasses position defines skull’s movement and the bow is
fixed to the lower arch determining relative distances.

41. 6- SICAT JMT:
The integration of CBCT diagnostics with CAD/CAM and other
objective data from biometric instrumentation, like the SICAT JMT
(Jaw Motion Tracker), gives us an opportunity to formulate a
definitive treatment plan with a common goal: optimal oral health.

42. Advantages:
• Real condyle-fossa relationship during jaw movement can be
reproduced for any point on the mandible
• In combination with CEREC SW 4.4, accurate articulation and
functional prosthetics are now possible for the first time
• SICAT OPTIMOTION all-digital workflow, which is based on the
movement of the individual patient, reduces the amount of
adjustment and adaptation effort required for a treatment
appliance
• Completely integrated workflow allows for diagnosis and
treatment planning in a single patient appointment

43. Software SICAT Function showing the combined CBCT image
with CAD/CAM image and jaw motion tracking data

44. Combining CAD/CAM and CBCT in a single practice with complete
integration creates a magical experience for the clinician and the
patient alike. CBCT provides an opportunity to provide an objective
assessment based upon results of the 3-D image, proper diagnosis,
and higher treatment plan acceptance and increased precision in
dental therapy.

45. The introduction of digital intra oral impression in
combination with Jaw tracking/CBCT, adds the advantages
of
• Time saving
• The reproducibility of the method
(Ender et al., 2015)

47. The jaw tracking system in this study consisted of a camera which can
obtain depth data and RGB data of the object simultaneously, a laptop
computer and Face shift software for data analysis and reconstruction of
the participant face.

49. C
OTHER
PROSTHETIC
APPLICATIONS

50. 1- Jaw tracking and TMD:
The study of mandibular motion is essential to the management of TMDs. The
need to duplicate the mandibular movements extra-orally led to the employment
of various methods to record and analyze them. Patient information can be
transferred to an articulator with mounted casts and thus, mandibular movements
can be evaluated. Questionnaires, clinical and radiographic examinations,
computed tomography and magnetic resonance imaging are some of the
instruments used to assess TMD. However, there is a scarcity of studies on
mandibular dynamics in TMD in the literature.

51. There are several limitations concerning bite registration and articulators.
• Bite registrations are static recordings; thus, articulators are unable to record real life
dynamics of occlusion during mandibular movements.
• Another basic limitation is the lack of visualization of condyle position, which is
essential to the management of TMDs.
• There are also various difficulties with transferring the registration onto the
articulator and mounting the casts with accuracy. (Kandasamy.,2015)

52. • Cone beam computed tomography (CBCT) in conjunction with jaw tracking devices
enabled the virtual evaluation of the occlusion and the TMJs and helped substantially
in overcoming these problems.
• These system presenting a real, 3D simulation of mandibular movements relative to
the patient-specific anatomy of the jaw. In addition, changes in the joint space during
resting or other positions can be recorded. Thus, the system can be used as a useful
supporting tool in the diagnosis, treatment, and management of TMDs.

53. TMD Diagnosis:
Examples:
• Detection of narrowing of intra articular distance during condyle sliding
movement along the articular eminence, (especially in patients with
severe facial asymmetry)
• The reduced intra-articular distance by physical loading may be
physiological.
• However, under repeated harmful activities like biting with wide mouth
opening and para-functions such as clenching and bruxism, the
physiological threshold can be crossed, and overloading and subsequently
TMDS may result.
Chang AR, Han JJ, Kim DS, Yi WJ, Hwang SJ. Evaluation of intra-articular distance narrowing during temporomandibular
joint movement in patients with facial asymmetry using 3-dimensional computed tomography image and tracking
camera system. J Craniomaxillofac Surg. 2015 Apr;43(3):342-8. doi: 10.1016/j.jcms.2014.12.015. Epub 2015 Jan 7. PMID:
25648068.

54. Treatment of TMD:
The SICAT Function software can combine cone bean CT, electronic JMT
data, and digital impressions; thus, it is capable of presenting a real, 3D
simulation of mandibular movements relative to the patient-specific
anatomy of the jaw. In addition, changes in the joint space during resting
or other positions can be recorded. Thus, the system can be used as a
useful supporting tool in the diagnosis, treatment, and management of
TMDs.

57. Other devices may be combined with jaw tracker during
recording of mandibular movements:
e.g., Deconditioning or relaxing the mandibular musculature by
the application of TENS.
With the help of TENS, complete relaxation of the muscles was
achieved, and the mandibular musculature was induced to
guide the mandible in the physiologic position.

58. • In maxillofacial prosthetic
dentistry, the use of tracking
system with 3D facial
scanner can help to confirm
that a prosthesis is
harmonized with a particular
patient’s aesthetics through
superposition with facial
scan data, with respect to the
occlusal plane, smile line,
and midline.
• In addition, loss of TMJ
function and muscle
contraction can occur due to
the development of scar
tissue after resective surgery
in patients with cancer. A
symmetric articulator cannot
reproduce or mimic
asymmetric and
individualized jaw
movements that are
characterized by severe
deflection.
2- Maxillofacial prosthodontics:
J.-E. Kim, et al., Complete assessment of occlusal dynamics and
establishment of a digital workflow by using target tracking with a
three-dimensional facial scanner, J Prosthodont Res (2018),
https://doi.org/10.1016/j.jpor.2018.10.003

59. 3- Detection of Phasic
Sleep Bruxism in OSA
Patients:
• Repetitive jaw muscle activity may
lead to development of sleep
bruxism in some individuals, which
is characterized by tooth clenching
or grinding and/or mandible bracing
or thrusting.
• Until now, the size and discomfort
imposed by jaw tracking recording
devices have been a major limitation
for human sleep studies in a natural
home environment.
• Recent non-invasive and easy to use
technological innovation has made
possible the continuous data
collection during sleep of mandibular
jaw movements.(Martinot et al,
2021)

60. 4- Studies of speech difficulties:
Jaw movement patterns were examined in subjects with childhood apraxia of speech
(CAS) . A movement tracking system was used to study jaw duration, displacement,
velocity, and stability.

61. A Comprehensive Treatment
Approach For Idiopathic Condylar
Resorption And AnteriorOpen Bite
With 3D Virtual Surgical Planning
And Self-ligated Customized
Lingual Appliance. (Rahman Et Al,
2019)
5- Perform proper diagnosis for comprehensive
treatment:

62. Studies suggest that patients with ICR remain undiagnosed and
unrecognized in the orthodontic clinic owing to the poorly
understood aetiology of the disease and lack of diagnostic tools.
ICR often causes occlusal and skeletal changes, TMJ dysfunction
and pain, and maxillofacial deformities.
The treatment plan included:
(1) presurgical alignment and levelling of the teeth in both arches
(2) jaw motion tracking (JMT) to detect mandibular movement
(3) 3-piece maxillary osteotomies with mandibular reconstruction
and bilateral coronoidectomies
(4) postsurgical correction of the malocclusion.