1. Maxillomandibular Jaw Relations Part-1

2. Orientation jaw relation Face bow -Parts -Types Arbitary Kinematic
Contents-
Definition
Classification
Orientation jaw relation
Face bow
-Parts
-Types
Arbitary
Kinematic
5. References

3. Maxillomandibular relations- is defined as any spatial relationship of the maxillae to the mandible ; any one of the infinite relations of the mandible to the maxilla (GPT 7).
CLASSIFICATION:
Boucher classified jaw relations into three groups,
1. Orientation relations
2. Vertical relations
3. Horizontal relations

4. 1- ORIENTATION RELATION
Orient the mandible to the cranium in such a way that when the mandible is kept in its most posterior position, the mandible can rotate in a sagittal plane around an imaginary transverse axis passing through or near the condyles. ( GPT-7)
THE AXIS CAN BE LOCATED BY THE FACEBOW.

5. ORIENTATION OF MAXILLA IN RELATION TO BASE OF SKULL
Plane of maxilla may be tilted in some patients , in such cases plane
of mandible will not be altered since it articulates with base of the skull. Hence , a maxillary tilt will alter the relationship of maxilla to mandible during different movements, also affect the level of occlusal plane .

6. Orientation of occlusal plane
The occlusal plane is defined as the average plane established by the incisal and occlusal surfaces of the teeth".

7. Importance of orientation of occlusal plane
Anteriorly, occlusal plane mainly helps in achieving esthetic & phonetic.
posteriorly, it forms a milling surface, where tongue & buccinator muscle are able to position the food bolus onto it , and hold it there during mastication.
Incorrect of occlusal plane would hamper esthetics, phonetics, & mastication. It may affect stability of complete denture & ultimately result in alveolar bone resorption.

8. A face bow - is 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 7)
DIAGRAMMATIC PRESENTATION
OF A FACE BOW
ARMAMENTARIUM
CONDYLE

9. A face bow-
Establishes the relationship between the maxillary arch and the horizontal plane.
Transfers this relationship to the articulator.
Provides for an accurate mounting of the maxillary cast to the articulator.

10. PARTS OF A FACEBOW U-Shaped frame Condyle rods Bite Fork
Locking Device
Orbital Pointer
Condyle rods
Orbital pointer
U-shaped frame
Locking clamp
Bite fork

11. TYPES OF FACE BOW (B) KINEMATIC FACE BOW (A) ARBITRARY FACE BOW
Facia type
Ear piece type
Hanau face bow[sring bow]
Slidematic[denar]
Twirl bow
Whip mix
FACIA TYPE HANAU FACE BOW ATTACHED TO HANAU ARTICULATOR
EAR BOW RECORD

12. ARBITRARY FACEBOWS
Make use of arbitrary or approximate points on the face as the posterior reference points.
The condyle rods are positioned on these points.
Sufficient for the fabrication of complete dentures, fixed partial and removable partial dentures.
Small error in location while using an arbitrary facebow will have only a negligible effect at the occlusal level.
The resiliency and life effect of the oral tissues make the exact transfer and location of the hinge axis unnecessary.

13. FASCIA TYPE : EARPIECE TYPE :
1.The earpiece face bow is converted to a fascia bow simply by removing the earplugs.
2.Utilize posterior reference points on the skin over the temporomandibular region.
3.Makes use of condylar rods instead of ear inserts.
EARPIECE TYPE :
1.Use the external auditory meatus
(which has a fixed relationship to the hinge axis)
as the arbitrary posterior point.
2.Each earpiece has a central hole that connects to the auditory pin on the articulator.
3.Does not require measurements or marks on the face.
4.The accuracy is similar to other arbitrary methods.

14. KINEMATIC FACEBOW 1.It is used to locate and transfer true hinge axis.
2.Complex instrument requiring the fabrication of clutches
which are attached to the lower jaws.
3.It requires more chair time .
4.It also requires the use of articulators with extendible
condylar shafts (e.g. Hanau H2X) which must be extended
to meet the stylus of the facebow.

15. References-
1.Prosthodontic treatment for edentulous patients- zarb-bolender 12th ed.
2.Textbook of prosthodontics-Deepak nallaswamy, 1st edition 2004.