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Libyan International medical University - Prosthodontics
Mandibular movements
Face bows and Articulators
Overview
Mandibular Movements
1. Anatomic Considerations
Tempero-mandibular Joints
Muscles
Ligaments
2. Basic Mandibular Movements
Opening and Closing
Protrusive (forward)
Retrusive (backward)
Lateral
3. Significance of studying Mandibular Movements
Facebows
Articulators
MANDIBULAR MOVEMENTS
Anatomic Considerations
Temporo-mandibular Joint (Also called the Cranio-mandibular joint)
The mandible articulates with the skull at the tempero-mandibular joint.
The condyle of the mandible fits into the mandibular fossa on the underside of the temporal
bone – so it is called Tempero-mandibular Joint
1. It is the articulation between the mandible and the cranium .
2. It is a bilateral articulation.
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Parts of the TMJ
 Articullar Tubercle and Fossa
 Intra-articular Disc
 Articular Eminence
 Fibres Of Lateral Pterygoid
 Upper Joint Compartment
 Lower Joint Compartment
The TMJ is a Synovial joint but different from others because here the articular surfaces of the
bony components are covered with dense fibrous connective tissue instead of hyaline
cartilage seen usually.
Also the TMJ alone has a fibrous intra-articular disc, to which muscle fibres are attached.
This disc divides the joint into two compartments upper and lower giving the mandible a wide
range of movements
The possible movements of the lower compartment is a simple hinge movement ,
while that in the upper is a sliding movement.
The mandible moves in all three planes during movement
Muscles
Muscles that move the mandible are under voluntary control, these muscles can be directed
to move the mandible in various directions
There are powerful muscles, which elevate and rotate the mandible so that the opposing teeth
may occlude for mastication.
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The muscles of mastication include the
1. Temporalis,
2. Masseter and
3. Internal (medial) and,
4. External pterygoids (lateral)
The first three of these are elevators.
The fourth (Lateral Pterygoid) is a guiding muscle, partly helping to depress the mandible.
Action of muscles during masticatory
movements.
Elevator jaw muscles - Closing
- Medial Pterygoid
- Superficial Masseter
- Temporalis
- Superior Division Of Lateral Pterygoid
Depressor jaw muscles - Opening
- Mylohyoid
- Digastric
- Inferior Division Of Lateral Pterygoid
Remember the muscles of mastication develop their greatest power within a short range of
vertical dimension – upto 400 pounds - Artificial teeth – maximum upto 30 pounds
Mandibular Ligaments
The different mandibular Ligaments are
1. Temporo-mandibular ligament
2. Sphenomandibular Ligament
3. Stylomandibular Ligament
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Basic Mandibular Movements are
1.
2.
3.
4.
5.
6.
Opening
Closing
Protrusive or forward
Retrusive or Backward
Right lateral
Left lateral
Types of Condylar Movements During opening or closing of the mandible
Rotational movement
Translational movement
 Rotational MovementAround the horizontal axis (hinge axis)
Opening of the jaw
Closing the jaw
 Translational movement
Wide Opening
Protrusive
Retrusion
Right Lateral
Left Lateral
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Border Movements of the Mandible
Border movements of the Mandible in Sagittal plane
Border Movement of the Mandible Horizontal Plane
1. Left lateral border.
2. Continued left lateral border with protrusion.
3. Right lateral border.
4. Continued right lateral border with protrusion.
Border Movement of the Mandible Frontal plane
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Lateral Movement (Bennett Angle [1])
Lateral Movement
(Bennett Shift [2])
FACE BOW
It is a calliper -like instrument used to record the relationship of the maxiIIary arch
to the hinge axis and then transfer this relationship to an articulator.It orients the dental cast
in the same relationship to the opening axis of the articulator
Uses of Face bow
• Establish the relationship between the maxillary arch and the Hinge axis
• Transfers this this relationship to the articulator
• Provides an accurate mounting of the maxillary cast to the articulator
Types of Face Bows
Ear-piece Face Bow
Fascia Type Face Bow
Facebow earpiece type
Facebow fascia type
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ARTICULATORS
Articulator
An articulator is are mechanical instrument that represents the temporomandibular joints and
jaws, to which maxillary and mandibular casts may be attached to simulate some or all
mandibular movements.
Function of Articulators
1. Prosthetic work is carried out in the absence of the patient.
2. It simulates but cannot duplicate all the possible mandibular movements.
3. Mounting dental casts for diagnosis and treatment planning.
4. Maintain jaw relation record during teeth arrangement.
Advantages :
1. Visualization of patient's occlusion from the lingual side .
2. Patient cooperation is not a factor , once the inter occlussal records are obtained from
the patient .
3. Chair time and patient appointment time is saved .
4. Saliva , tongue and cheeks are not interfering factors during using the articulators.
Requirements
1. Able to open and close in hinge motion.
2. Casts must be easily removed and attached
3. Articulator must have an incissal guide pin with a positive stop to maintain vertical
dimensions.
4. Rigid , accurate and of non corrosive materials.
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5. Guidance mechanism should be able to move freely and be accurately secured .
6. Minimal weight , not bulky and stable on the bench .
Special Requirements
1. The articulator should accept face bow transfer.
2. The condylar guidance should allow right lateral, left lateral and protrusive
movements.
3. The incisal guidance should be adjustable.
BASIC PARTS OF ARTICULATOR
• Upper member
• Lower member
• Mounting plates
• Condylar analogues
• Condylar guidance
• Incisal guide pin
• Incisal guide table
Types of Articulators
1. Based on the anatomic similarity to humans
1. ARCON and NON ARCON
2. Based on their functionality (adjustability)
1. Simple hinge articulators.
2. Fixed or mean value condylar path articulators.
3. Adjustable condylar path articulators:
Types of Articulators
Based on the anatomic similarity to humans
ARCON and NON ARCON
What is ARCON and NON-ARCON?
ARCON-ARticulator like CONdyle
Here the articulator is like the mandible, because it has the condylar head attached to the
Lower member and the condylar path is attached to the upper member
Non ARCON-ARticulator NOT like CONdyle
Here the articulator is different from the mandible in that the condylar head is in the Upper
member and the condylar path is attached to the lower member.
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Natural
Condylar Path
Condyle
ARCON
Non ARCON
Condylar
Path
Condylar
Element
Condylar Path
Condylar
Element
Types of Articulators
1. Based on their functionality (adjustability)
1. Simple hinge articulators.
2. Fixed or mean value condylar path articulators.
3. Adjustable condylar path articulators:
a. Semi-adjustable condylar path articulators
( NON-ARCON or ARCON )
b. Fully-adjustable condylar path articulators
Simple Hinge Articulators.
Records are fixed to the Articulator.
Simple Hinge Movements given by the Articulator.
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Fixed or Mean Value Condylar Path Articulators .
Adjustable Condylar Path Articulators :
a.Semi - adjustable condylar path articulators
( may be NON-ARCON or ARCON )
b. Fully - adjustable condylar path articulators .
Semi adjustable articulators
Here many features may be recorded from
the patients mouth and transferred to the
articulator. This type of an articulator is a
basic requirement for Balanced Occlusion
Fully Adjustable Articulators
This type of an articulator accepts transfer of
almost all the features needed to do complex
restorations which may be recorded from the
patients mouth. Commonly these articulators
allow adjustment of the intercondylar
distance according to the individual patient.
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