horizontal jaw relation

1. Horizontal jaw Relation
ANISHMA KRISHNAN

2. Introduction
 Good occlusion is a requirement for both dentulous
and edentulous patients.
 The human mandible can be related to the maxilla in
several positions in the horizontal plane and in this
the centric relation is significant due to its
usefulness in relating the dentulous and edentulous
mandible to maxilla ,where the teeth, muscles and
TMJ are in harmony.[i.e, a position of occluso-
articular harmony].

3. Jaw relation
Jaw relation is any relation of the mandible to
the maxilla.
There are 3 types of jaw relations;
Orientation jaw relation
 Vertical jaw relation
 Horizontal jaw relation

4. Following the orientation of maxilla and determination of vertical
dimension, the final relation to be recorded is the horizontal relation.
This is the anteroposterior relation of the mandible to the
maxilla in the horizontal plane.
The horizontal relation is classified as;
CENTRIC RELATION
ECCENTRIC RELATION – PROTRUSIVE AND LATERAL.
HORIZONTAL JAW RELATION

5. Horizontal jaw relation
CENTRIC RELATION
• Definition
• MIP
• Centric occlusion
• Significance of CR
• Methods to attain CR
(retruding mandible)
• Methods to record CR
1. static method
2. functional method
3. graphic method
ECCENTRIC
RELATION
Definition
Types-protrusive record
-lateral record

6. CENTRIC JAW RELATION
ACCORDING TO GPT 9;
The maxillo-mandibular relationship independent of tooth contact, in
which the condyles articulate in the anterio-superior position against
the posterior slopes of the articular eminence
In this position the mandible is restricted to a purely rotatory
movement from this unstrained , physiological (natural)maxillo-
mandibular relationship, the patient can make vertical, lateral protrusive
movements(eccentric).
it is a clinically useful ,repeatable reference position

7. • maxillo-mandibular
relationship
• independent of tooth
contact
• condyles articulate
• posterior slopes of the
articular eminence
• It has nothing to do with how teeth in both jaws occlude while the
condyles are in CR
• In an edentulous patient, the muscles would guide the condyles and
pull the joint into CR
• It is a bone to bone relation independent of tooth contact- it is a
physiological position , that is repeatable and recordable

8. It is the complete intercuspation of the
opposing teeth independent of the
condylar position , sometimes referred to
as the best fit of the teeth regardless of
condylar position, also called max
intercuspation
The occlusion of opposing teeth when
the mandible at CR, may or may
coincide with MIP
CENTRIC OCCLUSION MAXIMUM INTERCUSPAL POSITION(MIP)

9. The two most important criteria for centric relation
are:
• Proper alignment of the disc on the condyle. During
jaw closure with intact TMJ , the condyle disc
assemblies are pulled up by the triad of strong
elevator muscles
• The complete release of the inferior lateral
pterygoid muscles
CRITERIA FOR CENTRIC
RELATION

10. Significance of CR
• CR and MIP
in natural dentition -MIP may not coincide with CR, but
do not create any damage due to proprioceptive receptor in
PDL therefore direct the mandible away from defective
occlusion
In edentulous patients- no proprioception, therefore
cannot avoid a defective contact in CR thus the MIP must
coincide with CR in edentulous patient
• If CR not equal to MIP=pain of TMJ
• It is reproducible

11. FEATURES OF CENTRIC RELATION
It is repeatable , learnable and recordable position and it remains
constant throughout the life.
In case of edentulous patients centric relation act as proprioceptive center
to guide occlusal movements.
In case of dentulous patients proprioceptive impulses are obtained from
PDL.
It’s a reliable jaw relation because it is a bone to bone relation.

12. Functional movements like chewing and swallowing are performed in this
position because it is the most unstrained position.
It is the only jaw position that permits an interference free occlusion
Centric relation is the ideal arch to arch relationship and an optimum
functional position of jaws for the health , comfort and function of TMJ and
musculature.
Recording of an accurate centric relation is critical for the most cost effective
, time effective and trouble free prosthetic dentistry

13. RETRUDING THE
MANDIBLE:
• There are mainly 2 methods,
• PASSIVE METHOD - here the mandible is retruded
by the patient themselves following the dentists
instruction without any physical participation of
the dentist.
• ACTIVE METHODS -Here the patient is made to
retrude the mandible with physical assistance
from the dentist.

14. • By patient himself
• Relax, pull jaw back and close
• Push the upper jaw out and close
• Touch the posterior part of the upper
denture with tongue and close till rims
contact
• Swallow and close
• Tilt the head while doing this
• Protrude/retrude using finger of the patient
against chin
Passive method

15. • Assistance from the dentist
• Using thumb and forefinger-at the patients
chin-apply mild firm posterior force while
the patient close the rim
• Palpate the temporal and masseter muscle
to Relax them
• Dawsons bimanual palpation method
Active method

16. DAWSONS BIMANUAL
PALPATION
• dentist stand behind the patient
• Four fingers of both hand at lower border
of mandible
• Thumb over symphysis
• Ask patient to open then close slowly-
• as closing, fingers- apply upward lifting
force and Thumb-apply downward force
• This will guide to close in CR

17.  BIOLOGICAL CAUSES:
Lack of muscle coordination and patient closing habitually in protruded
relation
 PHYSIOLOGICAL CAUSES:
Patient unable to follow dentists instructions due to anxiety and stress
 MECHANICAL CAUSES
Poor adaptation of record bases
DIFFICULTIES IN RETRUDING

18. REQUIREMENTS OF CR RECORD
• To record correct horizontal relation of mandible to
maxilla
• To exert equalize vertical pressure
• To remain undistorted till mounting on articulator
Methods to record CR
1. static method
2. functional method
3. graphic method
RECORDING OF CENTRIC RELATION

19.  STATIC METHODS [pressure less methods]
These methods are employed without the use of functional or
excursive mandibular movements .They have been referred to as
‘tentative centric records”.
• ADVANTAGES
Simple , no extra devices are required
Can be recorded in one appointment
• DISADVANTAGES
Inaccuracy can result from lack of equalized pressure
Difficult to verify the accuracy of the record
Static method

20. 1. On the wax occlusal rim
2. After establishing vertical jaw relation
3. Retrude the mandible to attain CR
4. And ask the patient to close and hold in the position
5. And the rims are joined and sealed
6. After sealing remove from the mouth and articulate
 Sealing can be done by
I. Heating-how wax knife at the junction of rims
II. Pinning-by pins and staples
III. Nick and notch method
How to record

21. • Patient is asked to retrude the mandible in position.
• Up to 3mm of wax removed from mandibular occlusal rim from the premolar region till the distal end.
• One or two notches are cut on the corresponding areas of maxillary occlusal rim.
• Here one nick is cut anterior to a notch, a V shaped valley.
NICK prevents lateral movement.
NOTCH prevents anteroposterior movement.
TROUGH- created at the posterior region of the mandibular occlusal rim
• Prepared occlusal rim are inserted into patients mouth and taught to close his mandible in maximum
retruded position.
• Mandibular occlusal rim is cooled and inserted into patients mouth and closed in centric relation
A recording material will be loaded through the trough of mandibular rim- soft wax/ ZOE impression paste ,
used for the inter-occlusal recording
And removed after the material is set
Nick and notch method

23.  FUNCTIONAL METHOD OR CHEW IN METHOD
These methods utilize the functional movements of the jaws to record the centric relation
The patient is asked to do the movements in protrusion, retrusion and right lateral and left lateral
 ADVANTAGES
Vertical dimensions and CR can be determined
 DISADVANTAGES
Inaccuracy can result from :
 Displaceable basal seat tissues
 Resistance of recording mediums
 Lack of equalized pressure
 Patients must have very good neuromuscular coordination and be capable of following instructions.
Functional method

24. TYPES:
 Needles house method
 Patterson method
 Meyers method
 NEEDLE HOUSE METHOD :
• Fabrication of occlusal rim made from impression compound.
• Four metal beads or styli are embedded into premolar and molar areas of maxillary occlusal rim.
• Occlusal rim inserted into patients mouth and asked to close occlusal rim and make protrusive ,
retrusive ,right and left movement of mandible.
• When movements are made diamond shaped marking pattern rather than a line is formed on the
mandibular occlusal rim.

26.  PATTERSON METHOD
Occlusal rim made of modelling wax.
In trench or trough is made along the length of mandibular occlusal rim.
At 1:1 mixture of pumice and dental plaster is loaded into the trench.
Perform mandibular movement till predetermined vertical dimension.
Movement generates compensative curves in plaster.
 MEYERS METHOD
Meyer used soft wax to generate the functional pathway and record CR.

27. These methods are called so because they use graphs or tracings to record the centric jaw relation.
They are 2 types;
• GOTHIC ARCH TRACING.
• PANTOGRAPHIC TRACING.
 The general concept of this technique is that a pen like pointer is attached to one occlusal rim and a
recording plate is placed on the other rim
 the plate coated with carbon or wax on which the needle point can make the tracing
 when the mandible moves in a horizontal plane , the pointer draws the characteristic patterns on the
recording plate.
 The graphic methods are either intraoral or extraoral depending on the placement of the recording
device.
 The extraoral is preferable , because the former is more accurate ,visible, and larger in comparing with
the intraoral tracing.
Graphic method

28. Protrusive position
Eccentric position
Centric position

32. • Most accurate method to
record CR
• Easily verifiable
• Allows equalization of
pressure on the supporting
tissues
• Can also record eccentric
relation
ADVANTAGE OF GRAPHIC
METHOD
• Time consuming
• Difficult in locating the
centre of the arch
• Patient training to move
the jaw is difficult
DISADVANTAGES

33. • When centric relation is not coinciding with the patient , this can be due to
Incorrect horizontal relation of the mandible to the maxilla
Incorrect equalization of vertical contact.
Sometimes loss of retention , anterior or posterior premature contact etc can
cause errors.
Other errors can be positional or technical.
1. POSITIONAL ERRORS
2. TECHNICAL ERRORS
ERRORS IN CENTRIC RELATION

34. Failure of the operator in his registration of the correct horizontal
relationship.
Fail to record equalized vertical contact.
Application of excessive closure pressure by the patient at the time of
recording.
Changes in the supporting area.
POSITION ERROR

35. if record bases are not stable.
Frequent opening and closing of occluding device or articulator.
The slight shifting which occurs between the stage of final arrangement in
wax and the transfer to a permanent base material.
TECHNICAL ERRORS

36. An eccentric relation is any relationship of the
mandible to the maxilla other than centric relation.
The eccentric relations recorded are
• PROTRUSIVE
• LATERAL
These records are essential only if balanced
occlusion is planned for the denture.
Eccentric relation

37. ◦ Condyles move downward and forward for
potrutuion
◦ Methods to record protrusive relation are:
1. Functional method
2. Graphic method
3. Static method
Potrusive relation

38. ◦ A formulae is recorded to arrive at an acceptable
lateral inclination :
◦ L = H/8 + 12
◦ Where L = lateral condylar guidance
◦ H = horizontal condylar guidance.
◦ Eccentric relation is recorded with the same setting ,
same sitting and same equipment used for centric
relation.
Lateral relation method

39. Conclusion
Thus in horizontal jaw relation , centric relation is most important due to its
reliability , repeatability ,etc.
Centric relation is defined as the maxillomandibular relation in which the
condyles articulate with the thinnest avascular portion of their respective
articular discs in an anterosuperior direction against the posterior slopes of
articular eminences.
Centric relation are recorded by methods like passive method , graphic
method etc.
Eccentric relation contains protrusive and lateral relations which are also
recorded by the same sitting and with the same equipment as in centric
relations.

40.  Textbook of prosthodontics : V.Rangarajan.
 Winkler’s essentials of prosthodontics.
 Philip’s science of dental materials anusavice.
Reference