Horizontal jaw relations and it's complications

1. GOOD MORNING
No one can go back and make a brand new start…
But anyone can start now and make a brand new end…

2. HORIZONTAL JAW RELATIONS
2
Dr. Dipal Mawani

3. Contents
 Introduction
 Change in definitions
 Reason for change in definition
 Significance of centric relation
 Muscle involvement in CR
 Theories of CR
 Harmony between CR and CO
 Recording CR
 Factors influencing CR record
 Methods of recording CR
 Complications and errors in recording
 Methods of recording eccentric relation
 Review of literature
 Conclusion
 References
3

4. Introduction
Jaw relation / Maxillomandibular relationship:
Any spatial relationship of the maxillae to the
mandible ; any one of the infinite relationships of
the mandible to the maxillae (GPT 9)
Classification
 Orientation jaw relation
 Vertical jaw relation
 Horizontal jaw relation
4

5. • Horizontal Jaw relation - the relationship of the
mandible to the maxilla in a horizontal plane or it is the
relationship of the mandible to the maxilla in an antero-
posterior direction (medio-laterally).
• It can be of two types:
Centric relation
Eccentric relation
• Protrusive relation
• Lateral relation
• Left lateral
• Right lateral
5

6. Chronology of the changing definitions
1920- Mc Collum- Rearmost position
1952-Granger-uppermost,rearmost
1969-Stuart-RUM position
1977-American equilibration society –AS
position
6

7. 1978- Celenza
 Condyle disk assembly- superiorly and anteriorly against
posterior slope of eminence
 BOUCHER (1953)
The most posterior relation of the lower jaw to the upper
jaw from which lateral movements can be made at a
given vertical dimension
7

8.  ASH (1993)
A maxilla to mandible relationship in which the
condyles and disks are thought to be in the midmost,
uppermost position. The position has been difficult to
define anatomically but is determined clinically by
assessing when the jaw can hinge on a fixed terminal
axis (upto 25 mm). It is a clinically determined
relationship of the mandible to the maxilla when the
condyle disk assemblies are positioned in their most
superior position in the mandibular fossae, against the
distal slope of the articular eminence.
8

9.  GPT (1) -1956
The most retruded relation of the mandible to the
maxillae when the condyles are in the most posterior
unstrained position in the glenoid fossae from which
lateral movements can be made at any given degree of
jaw separation.
9

10.  GPT (3) -1968
The most retruded physiologic relation of the mandible
to the maxilla to and from which the individual can make
lateral movements. It is a condition that can exist at
various degrees of jaw separation. It occurs around the
terminal hinge axis.
10

11.  GPT (5) /(8) -1987
The maxillomandibular relation in which the condyles
articulate with the thinnest avascular portion of their
respective disks with the complex in the anterior-
superior positions against the shapes of the articular
eminencies. This position is independent of tooth
contact. This position is clinically discernible when the
mandible is directed superior and anteriorly. It is
restricted to a purely rotary movement about the
transverse horizontal axis.
11

12.  GPT-9 (2017)
Centric relation is defined as a maxillomandibular
relationship independent of tooth contact, in which the
condyles articulate in the anterior-superior position
against the posterior slopes of the articular eminences;
in this position the mandible is restricted to a purely
rotary movement; from this unstrained, physiologic,
maxillomandibular relationship, the patient can make
vertical, lateral or protrusive movements; it is a
clinically useful, repeatable reference position.
12

13. Significance of centric relation
 More definite than VD
 Most comfortable position(home of the mandible)
 Optimum position for health comfort and functioning of TMJ
 Movements of mandible start from here and end up here.
 physiologically acceptable position for mastication of food.
 Most posterior border position
 Pure rotations take place.
 Bone to bone relation
 Independent of position of tooth.
 Constant for an individual.
 Reproducible, repeatable and recordable.
 Acts as a reference point.
John J Sharry Complete Denture
Prosthodontics Third Edition
13

14. CRITERIA FOR REDIFINING CR OF THE CONDYLES
FROM RUM TO ANTERIOR-SUPERIOR POSITION
14

15. THEORIES
OF
CENTRIC
RELATION
The Muscle
theory
The
Osteofibre
theory
The
Meniscus
theory
The
Ligament
theory
Saizer P. Centric relation and condylar
movement: anatomic mechanism. J
Prosthet Dent 1971;26(6):581-91.
15

16. The Muscle Theory
Defense reflex
External pterygoid
muscles contracts
Halts the jaw
16
• Does not explain centric relation is same at all VD
• No anatomic explanation for posterior hinge movement
• No explanation for acuteness of needle point tracing
• If lateral pterygoid responsible: elliptical tracings
DRAWBACKS OF THE THEORY :

17. The Ligament theory
• Binds the elements of the
articulation
• Lateral radiographic views
• ‘Suspended’ or ‘Floating’
condyle
• Anatomic arrangement- not
well suited to halt retrusive
movement
17

18. The Osteofiber theory
• Posselt
• Fibrous stop - buffer
• “Retroarticular cushion”
• retrusive terminal stop
18

19. The Meniscus theory
• The posterosuperior surface unfolds along the roof of the
glenoid fossa
• Discs with their retromeniscal fibrous tissues--stop the
retrusive condylar movements
19

20. HARMONY BETWEEN CENTRIC RELATION AND
CENTRIC OCCLUSION
 CENTRIC OCCLUSION-the occlusion of the opposing teeth when
the mandible is in centric relation
 This may or may not coincide with MIP
 MAXIMUM INTERCUSPAL POSITION-complete intercuspation of
the opposing teeth independent of the condylar position
 CENTRIC SLIDE-movement of the mandible while in centric
relation from initial occlusal contact into maximum intercuspation
.
20

21.  In the natural dentition CO is usually located anterior to CR, the
average distance being 0.5 to 1 mm.
 If natural tooth has interferences in CR
 initiate impulses and responses that direct the mandible away from
deflective occlusal contacts into CO.
 Impulses created by closure of the teeth into CO establish memory
patterns that
 permit the mandible to return to this position, usually without tooth
interferences
21

22.  The edentulous patient cannot
control mandibular movements
or avoid deflective occlusal
contacts in CR in the same
manner as the dentulous
patient.
 Deflective occlusal contacts in
CR cause movement of denture
bases and displacement of the
supporting tissues or direct the
mandible away from this relation
22

23. Recording centric relation
1) Minimal closing pressure:
objective: to make opposing denture teeth touch
uniformly & simultaneously at first contact
2) Heavy closing pressure:
objective: to produce the same displacement of the soft
tissues that occur when patient masticates
23

24. FACTORS INFLUENCING CENTRIC RELATION RECORDS
Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. J
Prosthet Dent 2005;93:305-10.
1. Resiliency of supporting tissues
2. Fit of denture bases - Stability
- Retention
3. The TMJ and its associated neuromuscular mechanism
4. The character of the pressure applied in making the recording.
5. The technique used in making the recording and the associated recording devices
used.
6. The skill of the dentist.
7. The health and co-operation of the patient.
8. Maxillo-mandibular relationship .
24

25. 9. Posture of the patient.
10. Character or size of the residual alveolar arch.
11. Amount and character of saliva.
12. Size and position of the tongue.
13. Psychic or emotional tension.
14. Protective reflex action caused by faulty occlusal contacts.
15. Materials and equipment used for record making.
16. The use of articulators that do not accurately adjust to all inter occlusal check
records.
25

26. Methods of recording centric relation
Classification by Different Authors:
1. By Boucher
a. Static methods — interocclusal record with/with out central bearing
devices and tracing devices
b. Functional methods — chew-in technique
a) Needles technique
b) House technique
c) Patterson technique
26

27. 27
2. By Heartwell
1. Functional methods (chew-in)
a) Needles House method
b) Patterson method
2. Graphic Method
a) Intraoral devices
b) Extraoral devices
3. Physiological or tactile or
inter occlusal check record method

28. • By Kapur & Yurkstas (1957)
28

29. Static method
 Involves guiding the mandible in CR with the maxillae then making
a record of the relationship of the two occlusion rims to each other.
 Advantage - minimal displacement of the recording bases
 Record made with wax or plaster
29

30. Functional method
 Involves functional activity or movement of the mandible at the
time the record is made.
 Disadvantage - causes lateral and anteroposterior displacement of
the recording bases
 Includes the various chew-in techniques
30
needleshouse meyer’s patterson

31. Functional method
“Historical development”
 Greene– Used plaster and pumice mixture.
 Needles– Mounted three studs on maxillary rims.
 Patterson – Used corborandum and plaster mixture.
 Meyer – Used soft wax occlusal rims, tin foil placed and functional
movements done.
 Boose – Used Gnathodynomometer.
 Shanahan – Cones of soft wax.
31

32.  In 1905 Christenson used 'impression wax' for bite records.
 One early method was to have the patient close in a retruded position
and attach the rims together for mounting on an articulator usually
with staples or by sealing the rims with a hot instrument.
32

33.  Schuylor (1932) said that modeling compound was preferable to wax for
occlusal records because it can be softened more evenly, cools slower
and doesn't distort as much as wax.
 Boos (1959) felt that it was important to avoid torsion when recording
Centric relation. Wax or compound, which required application of force,
could displace the mandible. Thus a material such as plaster or ZnO
Eugenol paste was more accurate.
33

34.  Hanau was one of the first individuals to be concerned about
equailization of pressure when recording the bite. He coined the
term "Realeff' which is formed by the beginning letters of the words
'resilient and like effects‘
 Payne (1955) and Hickey (1964) stated a preference for plaster
because less material had to be placed in the patient's mouth for
the record.
34

35.  In 1910 Green invented his 'PRESSOMETER' in an early attempt to
equalize the pressure of recording centric relation . It consisted of
celluloid strips placed between the maxillary and mandibular
occlusion rims on the right and left sides. If the pressure were
unequal, the rims would "hold" one strip while the other could be
removed.
 In 1954 Brown recommended repeated closure into softened wax
rims.
35

36.  Wright(1939) described the four factors he believed affected the
accuracy of records:
(i) resiliency of tissue
(ii) saliva film
(iii) fit of bases
(iv) pressure applied.
He concluded that the best technique was to record the occlusal
record at zero pressure
36

37.  Kingery (1952) discussed 2 fundamental principles that contribute
to the success of direct recording method:
1) The dentist's ability to recognize the Centric relation position
2) Understanding that the recording medium directly influences the
pressure developed in the recording and the subsequent
equilibration of the recording.
37

38. Physiologic technique
 Shanahan (1955)
 cones of soft wax placed on the mandibular occlusal rim
 patient was asked to swallow repeatedly.
 He believed that during swallowing, the tongue forced the mandible
into Centric relation position.
 The cones of soft were then moved and Centric relation was
recorded using this method.
38
Shanahan TEJ. Physiologic jaw relations and occlusion of
complete dentures. J Prosthet Dent 2004;91(3):203-05.

39. Indications
Supporting tissues are excessively displaceable
Large awkward tongues
Uncontrollable/ abnormal mandibular movements
Check occlusion of teeth in existing dentures.
39

40. FUNCTIONAL ( CHEW IN )
 Patterson and Needle House Technique.
 Both based on same principle.
i.e. the patient produces a pattern of mandibular
movements by moving the mandible to protrusion,
retrusion, and right and left lateral.
40

41. Needle-House
Method
CR
41

42. 42

43. Patterson Method
43

44. 44

45. Meyer’s technique:
-used soft wax occlusal rims.
-tinfoil was placed over the wax and lubricated.
-patient performed functional movements to produce a
wax path
-plaster index was made
45

46. STATIC OR PRESSURELESS METHOD
Nick and Notch method :
46

47. STATIC OR PRESSURELESS METHOD
Nick and Notch method :
 ZOE and plaster can also be used
 patient is asked to close in centric with guidance.
 anterior part of the rims should just be touching and not press
against each other.
 Aluwax will flow into the nick and notch, thus securing the
record.
47

48. DIRECT INTEROCCLUSAL RECORDS
 Physiologic method or static method.
 1756 Phillip Pfaff first described
 Three factors influence the record :
1. Amount of pressure exerted on the displaceable
tissues in the joints
2. The patient's comfort.
3. The number of reference points used to make the
record.
48

49.  A non precise jaw record obtained by placing a thermoplastic
material, usually wax or compound, between the edentulous ridges
and having the patient close into the material.
 Also known as the 'mush', 'biscuit' or 'squash bite'
49

50. GRAPHIC RECORDINGS
The earliest graphic recordings were based on studies
of mandibular movements by Balkwill in 1866.
The intersection of the arcs produced by the right and
left condyles formed the apex of what is known as
GOTHIC ARCH TRACING.
50

51. “Gothic” name originate from ancient Gothic
people’s houses (Barbarian tribes of Rome)
GOTHIC ARCH TRACING

52. Historical development
 Hesse (1897)– First to make a Needle point tracing.
 Gysi (1910)– Improved needle point tracing.
Phillips (1927)– He developed a plate for the maxillary
occlusal rims and a tripoded ball bearing mounted on a
jackscrew for the mandibular occlusal rim.
He called this as the "Central Bearing Point".
52

53. 53
What does the tracing represent?
Border movements of the mandible
in the horizontal plane and its apex
is the most retruded position
(relaxed position) of the mandible.
Advantage of reproducibility – can
verify the centric relation.

54. IMPORTANT FACTORS TO BE CONSIDERED WHEN
COMPLETING A GRAPHIC TRACING
1. The record bases may become displaced if the
central bearing point becomes "off center" when the
mandible moves into excursive positions.
2. If a central bearing device is not used, more resistance to
horizontal movements occurs with the occlusal rims.
3. It is difficult to locate the center of the arches (so that
the forces may centralized)
54

55. 4. Ridges that have no vertical height also cause difficulty
in stabilization of a record base.
5. Large tongues result in difficulties in record base
stabilization.
6. Recording devices may not be compatible with normal
physiologic mandibular movements.
55

56. 7. The tracing is considered unacceptable with a blunted
apex; only sharp or pointed apexes are considered
acceptable. If double tracing occur, this usually indicates
that the movements were not coordinated (If double
tracings occur, then it is necessary to make additional
tracing)
8. It is necessary to perform the graphic tracing at the
predetermined vertical dimension of occlusion.
9. Graphic methods record eccentric relations.
56

57. Classification of Graphic recordings
1. Intraoral tracings
2. Extraoral tracings

58. Intraoral Tracings
• The intraoral tracings cannot be
observed during the tracing; therefore,
the method loses some of the value of
a visible method.
• Since the intraoral tracings are small,
it is difficult to find the true apex.
• The tracer must be definitely seated in
a hole at the point of the apex to
ensure accuracy when injecting plaster
between the occlusion rims.

59. Intraoral tracing assembly

60. Intraoral tracing

61. Types of tracers
Intraoral Tracing Devices:
Eg: a. Coble tracer
b. Swissdent ball bearing bite tracer
c. Micro tracer
d. Functiograph

63. Extraoral Tracings
• Larger than the intraoral tracings because they are
made further from the centers of rotation, and the
apex is more discernible.
• Visible while the tracing is being made. Therefore,
the patient can be directed and guided more
intelligently during the mandibular movements.
• The stylus can be observed in the apex of the
tracing during the process of injecting plaster
between the occlusion rims, and no hole is
required.

64. 2. Extraoral Tracing Devices:
Eg: a. Hight tracer
b. Sears tracer
c. Phillips tracer
d. Chandra tracer
e. Stansbery tracing device

65. Chandra tracer
• By, K.Chandrasekharan
Nair, is a 2 component
assembly.
• The upper bearing plate –
pencil holder
• The lower bearing plate –
central bearing screw and
tracing platform of
dimensions 35×47mm, pins
to hold a drawing sheet.

66. Hight tracer

67. Extraoral tracing (Hight tracing device)

68. Extraoral tracing

69. Evaluation of Gothic Arch
Tracings:
69

70. Classical, pointed form
The symmetry indicates an undisturbed
movement sequence in the joints and uniform
muscle guidance.
Classical flat form
Indicates distinct flat lateral movements of the
condyles in the fossa.
70

71. Weak Gothic arch tracing
Indicates a lax and negligent performance of the
movements. The registration must be repeated:
Stronger movements must be demanded from
the patient.
Asymmetrical form
The tracing indicates a distinct inhibition of the
forward component of the lateral movement in
the right joint.
71

72. Miniature Gothic arch tracing
This tracing points restricted mandibular
movements.
•Due to badly fitting and pain-causing record
bases or
•Long standing edentulous state with inhibited
movement in the joints.
Vertical line protrudes beyond the arrow
point
forcible retraction or pushing of the mandible
or tracing obtained with protruded mandible
72

73. Drawbacks of gothic arch tracings:
Relatively time consuming.
Requires well defined, non-displaceable upper and lower
alveolar ridges to allow stable, retentive acrylic bases
Large tongues can cause base movement during tracing.
Truly excursive movements are often difficult to recreate
by patients thus producing an imperfect arrow head
tracing which then requires element of interpretation.
73

74. CEPHALOMETRIC RECORDINGS
Pyott and Schaeffer described the use of
cephalometrics to record centric relation.
These radiographs were used to determine centric
relation and the appropriate vertical dimension of
occlusion.
This practice, however, never gained widespread
usage
74

75. Methods for assisting the patient to retrude the
mandible
1. Instruct the patient by saying, "Let your jaw relax,
pull it back, and close slowly and easily on your back teeth.“
2. Instruct the patient by saying, "Get the feeling of
pushing your upper jaw out and closing your back teeth
together."
3. Instruct the patient to protrude and retrude the
mandible repeatedly while he holds his fingers lightly
against his chin.
75
Prosthodontic treatment for edentulous patient . Boucher’s, ninth edition

76. 4. Instruct the patient to turn the tongue backward toward the
posterior border of the upper denture.
5. Instruct the patient to tap the occlusion rims or back teeth
together repeatedly. It is believed that the center of
muscle pull will gradually work the mandible back.
76
Bissasu M. Use of the tongue for recording centric relation for
edentulous patients. J Prosthet Dent 1999;82:369-70.

77. 6. Tilt the patient's head back while the various
exercises just listed are carried out. This will place tension
on the inframandibular muscles and tend to pull the
mandible to a retruded position.
7. Having the patient swallow. Swallowing may bring the
mandible to a retruded position and may be an aid in
retruding the mandible to CR.
77

78. Mandibular
Guidance
methods
Patient guided
recording
Operator guided
recording
78

79. Patient
guided
Recording
Schyulor
technique
Gothic arch
Tracing
myomonitor
Physiological
technique
79

80. 1. SCHUYLER TECHNIQUE (1932)
 This technique involves the
patient placing the tip of the
tongue to the back of the palate
and closing into a horseshoe
shape of softened wax with light
pressure.
Limitations:
 Wax may or may not be
uniformly softened which can
lead to inaccuracies in recording
80

81. 2. PHYSIOLOGICAL TECHNIQUE
(SHANAHAN- 1955)
Uses cones of soft wax
placed posteriorly while
patient swallows several
times.
 More appropriate for
edentulous patients.
81

82. 3. GOTHIC ARCH TRACING
82

83. 4. MYO MONITOR
 It is an electrical jaw muscle stimulating device which is
reputed to achieve muscle relaxation producing a
neuromuscular mandibular position.
83

84. Operator
guided
recording
Chin point
Guidance
method
3 point
Finger chin
guidance
method
Bimanual
Manipulation
method
Anterior
guidance :
•Lucia jig
•Tongue blade
•Leaf gauge
•OSU woelfel
Power centric
registration
method
84

85. CHIN POINT GUIDANCE METHOD GUICHET(1970)
Risk with this method is ease
with which condyles can be
over retruded
85

86. BIMANUAL MANIPULATION METHOD -
Peter dawson(1980)

88. Operator-guided recording of CR

89. Anterior deprogrammer
 Types: 1. Tongue blade-Stuart
2. Anterior jig - Lucia
3. Leaf gauge - Long
89

90. Operator-guided recording of CR

91. ANTERIOR GUIDANCE BY OSU WOELFEL GAUGE
 This method was developed by Woelfel at Ohio
state university and aims to simplify Lucia jig
technique while still achieving an anterior point
contact at the retruded position.
This specially designed device has a graduated
acetate bite platform, the position of which is
adjusted antero- posteriorly until the teeth are
minimally out of contact.
Registration support wafer can then be added to
make records.
91

92. POWER CENTRIC REGISTRATION METHOD
92

93. Complications
in recording
Centric relation
Biological
difficulties
Psychological
difficulties
Mechanical
difficulties
93

94. 94

95. Causes of
Error in recording
Centric relation
Technical causes
Errors of patient
origin
95

96. Consequences of recording incorrect
centric relation
1. TMJ dysfunction
2. Mucosal ulceration and irritation
3. Spasm of muscles
4. Resorption of bone
96
96

97. Eccentric relation records.
An eccentric maxillomandibular relation is any
relation ship of the mandible other then centric position.
• The relation recorded by moving the mandible forward is
called protrusive relation record.
• The relation recorded by moving the mandible mesio-
laterally is called lateral relation record.
• Eccentric relation depends on the shape of the
mandibular fossae.
97

98. Methods of recording eccentric relation.
1. Functional method- Needles-House and patterson
technique.
2. Graphic method.
3. Tactile or Direct check methods.
4.Pantography
98

99. Graphic method
 A distance of 5-6 mm is measured from the apex and is
marked.
 Instruct the patient to protrude until the stylus rests on the
marked point.
 Inject the plaster between the occlusal rims and allow it to set.
 Remove the occlusal rims from the mouth and transfer this
relation to the articulator.
the eccentric jaw relation is made with a protrusive distance of
5-6 mm because it is believed that with a shorter distance, the
condyle would not move down its path and the distance is
sufficient to be recorded on the articulator.
99

100. Tactile or direct check record method
.
This is the most common method to make a protrusive
relation record using soft wax. The preferred time to
make the eccentric jaw relation records is after the teeth
have been arranged for try in.
100

101. Lateral relation records
more harmony will exist between the mandibular movements
and cuspal inclines.
The most common methods of lateral relation record are.
1.Graphic method.
2.Check bites of wax.
3.Positional records of stone/plaster.
4.pantography.
101

102. Graphic method.
 Requires 2 records
-one on left side
-one on right side
 Articulator is adjusted as record is made
 Additional layers of wax are placed on balancing
side
 Hanau formula- L=H/8+12
102

103. 2) WAX CHECK BITES:
taken at lateral positions and it is desire able
to have more than one record at each position
3) PLASTER/STONE POSITIONAL RECORDS:
records are taken at lateral extremes of the intra
oral or extra oral tracings
103

104. 4) PANTOGRAPHY:
one of the best method to study mandibular
movements
record tracing in horizontal and sagittal plane
104

105. 105

106. Review of Literature
 Tradowsky and Kubicek
 Central bearing screw – line connecting the tips of the right
and left maxillary premolars
 Avoid levarage flexure
 Physiologic equilibrium point of mandible
 Where the resultant force of vectors of all closing muscles of
jaw during maximum contraction intersect the occlusal plane

107.  Buxbaum (1993)
 EMG studies of muscle activity
 CR positioning induces activity in both temporal
muscles and in supra-hyoid and infra-hyoid muscles
 Little contribution from masseter and lateral pterygoid
 Anterior temporal fibres- stabilizer
 Middle and posterior fibres with suprahyoid muscles-
retrude the mandible
 Lateral pterygoid- stabilizes the disc

108.  Muraoka and Iwata
 Compared one-handed and bimanual methods
 Chin point guidance positioned the mandible too posteriorly
to be considered as CR

109. CONCLUSION
 Goal of complete denture therapy is to
achieve harmonious relation with the
masticatory system. Centric relation is the
starting point towards achieving occlusal
harmony
 Irrespective of the method used clinical
checking and rechecking must be done
throughout the entire denture construction
 Skill of dentist and cooperation of patient
most important factor
109

110. BIBLIOGRAPHY
1.Prosthodontic treatment for edentulous patient . Boucher’s, 10th
edition
2.Syllabus of complete dentures. Heartwell,3rd edition
3.Dawson- evaluation diagnosis and treatment planning of occlusal
patient
4.Complete denture prosthodontics –John J Sharry 3rd edition
5.Winkler essentials of complete denture 2nd edition
6. Using the term “centric “–William Avant JPD 1971;25
110

111. 111
7.Mandibular centricity :centric relation-JPD 2000;83
Factors influencing centric relation record in edentulous mouths JPD
1964;14
8.Critical evaluation of methods to record centric jaw relation –journal of
indian prosthodontic society july 2009
9.Physiologic vertical dimension and centric relation –JPD 2004;91
10.Centric relation and condylar movement:Anatomic mechanism.
JPD1971;vol 26:581-590
11.An appraisal of the literature on centric relation.part 1 ,Part 2, part 3 –
journal of oral rehabilitation 2000;27
12.Centric relation record-Historical review. JPD1982;vol47:141-144

112. 13.Determining vertical dimension of occlusion and centric relation.
JPD1970;vol24:18-24
14.What is centric relation? JPD1961;vol11;16-21
15.A technique for recording centric relation. JPD1964;vol 14:492-505
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18.The Maxillomandibular relationship of centric relation.JPD1959;vol6:922-
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113. Thank you
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