ORIENTATION JAW RELATION- Dr. Anil V Koruthu

1. Dr Anil V Korothu
Reader
Royal dental college

2. CONTENTS
• Introduction
• Maxillomandibular relations
• Orientation jaw relation
• Facebow
• Arbitrary facebow
• Kinematic facebow
• Parts of facebow
• Facebow transfer
• Clinical procedures for recording orientation jaw relation
• Mounting on the articulator
• Reference

3. INTRODUCTION
The relationship of mandible to maxilla and their orientation to
cranium is very important consideration in prosthodontics.
The recorded jaw relation are then transferred to articulator which
simulate these movements and assessed in arranging artificial
tooth accordingly.

4. MAXILLOMANDIBULAR RELATIONS AND RECORDS
• Any spatial relationship of maxillae to mandible ; any one of infinite
relationships of the mandible to the maxillae (GPT8)
It can be classified as
Orientation relations
Vertical relations
Horizontal relations

5. ORIENTATION JAW RELATION
DEFINITION
‘The jaw relation when the mandible is kept in most posterior position , it
can rotate in the Sagittal plane around an imaginary transverse axis
passing through or near the condyle’s (GPT)

6. • These establish the relationship of the maxilla to the base of the skull or
cranium
• This is the first jaw relation to recorded
• It establishes the angle or tilt of the maxilla in the three reference
planes
• The mandible moves against a fixed maxilla and to accurately
reproduce mandibular movements,it is necessary to establish and record
the tilt of maxilla
• To record the angulation of the maxilla, a plane should be formed with
at least two posterior reference and one anterior reference

8. • As the mouth opens and closes in centric relations , the movements of
the condyles in the initial stages (up about 12mm) of opening and final
stages of closing, is a rotational movement in the horizontal axis
following an arc of circle.
• Axis of rotation passes through the centre of both condyles.
• The condyles are centered in the glenoid fossa during this rotational
movement.
• If the centre of condylar rotation can be determined it will correspond
to the two posterior reference point necessary to form a plane for the
maxilla.

9. • This is a repeatable border position and can be located consistently.
• A third reference point located anteriorly in the maxilla-infra orbital
notch or nasion will complete the plane.

11. FACE BOW
Definition
“ a caliper like instrument used to record the spatial relationship of the
maxillary arch to some anatomic reference point or points and then
transfer this relationship to an articulator ; it orients the dental cast in
the same relationship to the opening axis of the articulator”.(GPT 8)
Types of face bow
• 1.arbitrary face bow
• 2. kinematic/hinge face bow

12. INDICATIONS OF FACEBOW
• Face bow may be indicated when:
Balanced occlusion is desired.
Vertical dimension is subjected to change.

13. ARBITRARY FACEBOW
Definition:
• A device used to relate the maxillary cast to the condylar elements of
an articulator using average anatomic landmarks to estimate the
position of the transverse horizontal axis on the face. –(GPT8)
• Most commonly used two types
1.Earpiece type
2.Facia type

14. KINEMATIC FACEBOW
Definition:
• A face bow with adjustable caliper ends used to locate the transverse
horizontal axis of the mandible-(GPT8)
• It locates the true (exact) centre of condylar rotation or transverse
horizontal axis.
• Preferred in full mouth reconstruction.
• Requires fully adjustable articulator.

15. PARTS OF FACEBOW
• U-shaped frame
• Condylar rods
• Bite fork
• Locking device
• Orbital pointer with clamp

17. U SHAPED FRAME
 Main frame
 All other components attached to the frame with clamps
 Large – extend from TMJ region to 2 to 3 inches anterior to the face,
 No contact with face
 Records the plane of the cranium

18. CONDYLAR RODS
 2 small metallic rods on either side of the free end of U-shaped
frame that are placed on determined centre of condyle.
 The calibrations on either side are equalized and then locked.

19. BITE FORK
• U-shaped rod attached to occlusal rims while recording orientation
relation.
• Attached to frame with a rod called stem
• Inserted 3mm above the occlusal surface of occlusal rim with
impression compound.

20. LOCKING DEVICE
 There are three locking devices
 Locking clamp for bite fork : it attaches the bite fork to U shaped frame.
 Locking clamp for orbital pointer pin :locks the orbital pin onto Shaped
rod
 There is another locking screw for condylar rods

22. ORBITAL POINTER PIN
• Designed to mark anterior reference point .
• It is adjusted after marking anterior reference point on the patient.
• This enables transfer of third reference point

23. FACEBOW TRANSFER
• The procedure of transferring the orientation of maxilla to the
articulator involves
1. face bow record
2. face bow mounting

24. CLINICAL PROCEDURES FOR RECORDING ORIENTATION JAW
RELATION
• Maxillary occlusal rim is inserted in to the patients mouth contoured
and all the required guidelines are marked.
• A point 13mm from tragus of the ear on the canthotragal line is marked
on both sides.

25. • The bite fork is flamed and attached anteriorly to the maxillary occlusal
rim, 3mm above the incisal plane and parallel to the occlusal plane .
The maxillary rim with attached bite fork is inserted in to the patients
mouth. The parallelism and centering of the attached bite fork is
verified.

27. • The U frame is supported by two fingers and gently rotated and
inserted in to the stem of the bite fork in the patients mouth.
• The condylar rods are unlocked and the condylar heads are then placed
in the patients left and right condylar centers on the previously marked
points.
• The third points of reference (infra orbital notch) is palpated and the
orbital point is set.

29. • The condylar rod readings are equalized on both sides and the locking
screws are tightened. Orbital point is also tightened.

30. • Once the entire apparatus in position the condylar rods ,orbital pin and
the bite fork are verified for any movements, alignment and parallelism
• The contoured mandibular occlusal rim may be used during the transfer
to stabilize the maxillary rim . The face bow record is removed from
patient by loosening only the condylar screw . The record is now ready
to be mounted on the articulator. This complete the face bow transfer
and then it is transferred to the articulator

32. MOUNTING ON THE ARTICULATOR
• The articulator is programmed first : the incisal guide pin is set first .
the horizontal condylar inclination is setted 40 degree and the Bennet
angle at 20 degree

33. • The face bow record is now mounted on the articulator as follows . The
condylar rods are attached to the auditory pin the bite fork is stabilized
and the orbital pin is made to coincide with orbital axis plane indicator.
• The incisal pin is locked and the incisal table is set horizontally .

35. • The upper member of the articulator is swung open, plaster is mixed
and placed on the cast and the upper member closed slowly , until the
incisal pin fully touches the incisal table.
• Excess plaster is trimmed once the plaster is set.facebow is now
removed by loosening all the locking device

37. REFERENCE
• TEXTBOOK OF PROSTHODONTICS-RANGARAJAN AND
PADMANABHAN

38. Thank you…..