occlusion

1. Centric Relation

2. MANDIBULAR CAST MOUNTED IN
CENTRIC RELATION – WHY?
• Reference position to evaluate MIP and a position to which we can
restore to – so we want to evaluate its relation to MI
• Only position from which all other jaw positions can be reached
• What is the definition of centric relation?
• Other definitions that refer to the most retruded position are “older”
definitions - Boucher: 1953, GPT-1(1956), GPT-2,3,&4 (1977)
• Even though centric relation is the anterior superior position of the
condyles, in 90% of the population, it is a mandibular position that is
retruded compared to M.I. at the tooth level
The maxillomandibular relationship in which the condyles articulate with the
thinnest avascular portion of their respective disks with the complex in the
anterior-superior position 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 [GPT-5,6,7,& 8, 9] 1987-
2005

3. DEFINITIONS: GPT - 9
• Centric occlusion: the occlusion of opposing teeth when the mandible is in centric relation;
this may or may not coincide with the maximal intercuspal position.
• Retruded contact position: contact of a tooth or teeth along the retruded path of closure;
initial contact of a tooth or teeth during closure around a transverse horizontal axis.
• Centric relation: 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 un- strained, physiologic, maxillomandibular
relationship, the patient can make vertical, lateral or protrusive movements; it is a
clinically useful, repeatable reference position.
CONCEPTS REGARDING CR AND TERMINAL
HINGE AXIS 1987 TO PRESENT

4. BIMANUAL MANIPULATION

5. ANTERIOR DEPROGRAMMER/
PROGRAMER

6. Most consistently reproducible;
• Strohaver: 1972, bimanual most consistent
• Kantor, M. E., Silverman, S. l. and Garfinkel, L.: 1973, bimanual .05mm;
anterior jig .07mm
• Hobo, S. and Iwata, J.: 1985, bimanual most consistent
• McKee: 1997, bimanual .11mm
• Tarantola,GJ; Becker, IM; Gremillion,H: 1997, bimanual .10mm
• Keshvad, A.; Winstanley, R. 2003, bimanual most consistent, gothic arch least
consistent
• McKee: 2005, anterior programmer .11mm
Position:
• Strohaver: 1972, anterior jig most superior
• Lundeen, H.: 1974, anterior stop most superior
• Kantor, M. E., Silverman, S. l. and Garfinkel, L.:1973 – bimanual and anterior jig
intermediate (compared to chin point guidance and myomonitor)
• Hobo, S. and Iwata, J.: 1985, bimanual most superior
Summary: Anterior stop and bimanual most reproducible .05 - .11mm at condylar
level
Summary: Anterior stop and bimanual most superior position

7. LEAF GAUGE
Williamson, E. H., et al.: Centric relation: A comparison of muscle determined position and operator
guidance. J. Prosthet. Dent., 39:561-564,1978. - Bite hard positioned condyles
posteriorly/inferiorly; bite easy seated condyles

8. WE USED THE CHIN POINT GUIDANCE
BECAUSE:
• The hand not manipulating the mandible is free to:
- Retract the lips to visualize the slide and occlusal relationships
- Hold articulating ribbon or tape to mark the IPC
• It is easier to use for the first time manipulating the mandible
Careful not to apply pressure
to distalize the condyle
There is a position more retruded than CR

9. That guided occlusal relationship occurring at the most retruded position of the
condyles in the joint cavities. A position that may be more retruded than the centric
relation position GPT - 8
RETRUDED CONTACT POSITION ●
CENTRIC RELATION ● Superior anterior condylar position
MAIMUM INTRERCUSPATION ● Not defined by condylar position
?
If this position is evaluated as physiologic it is the position we will restore to when
minimal restorations are required

10. What occlusal discrepancies can patients can perceive
• Tryde et al. - 50% of patients .01mm
• Siirila & Laine - 25% of patients certain .008mm - .01
40% of patients suspected .008mm - .01
A hair is .about 40 μm or .04 mm. A little more than a doubled over piece of
Acufilm which is 18 μm or .018mm x 2 = .036mm
Shim stock Thin 8 Microns
BOARD QUESTION

11. We recorded the centric relation jaw position at
CO
• Using a registration paste at C.O. with the Initial Point Contact in
contact
• Reason: eliminate possible error
due to closing on a less than
accurate rotational center because
the T.H.A. was found by it’s average
anatomic location to the external
auditory meatus
• Advantage: immediate verification
of C.R. record if IPC are the only
perforations in the record

12. WE ALSO VERIFIED THE RECORD BY RE-
INDEXING THE TEETH INTO THE RECORD
But the teeth didn’t travel freely into the indexes - there was an
interference – WHY?
When mandible guided to
CO, registration material
flowed behind distal
inclines of the lower teeth
and set
Sectioned registration
material showing material
behind the lower last
molar

13. WE ALSO VERIFIED THE RECORD BY RE-
INDEXING THE TEETH INTO THE RECORD
But the teeth didn’t travel freely into the indexes - there was an
interference
When mandible opened,
the condyles came
forward and rotated
bypassing the set
material

14. WE ALSO VERIFIED THE RECORD BY RE-
INDEXING THE TEETH INTO THE RECORD
But the teeth didn’t travel freely into the indexes - there was an
interference
To re-index the teeth into
the bite registration the
mandible was guided to CR
and now closed on the CR
arc of closure bumping into
the registration material

15. WE ALSO VERIFIED THE RECORD BY RE-
INDEXING THE TEETH INTO THE RECORD
But the teeth didn’t travel freely into the indexes - there was an
interference
To eliminate this
interference the
registration has to be
trimmed

16. WE ALSO VERIFIED THE RECORD BY RE-
INDEXING THE TEETH INTO THE RECORD
But the teeth didn’t travel freely into the indexes - there was an
interference
To eliminate this
interference the
registration has to be
trimmed to allow the
mandible to close without
interference to verify the
indexed co position

17. CENTRIC RELATION RECORD CAN BE
RECORDED USING WAX BUT
• Have to record position at an open vertical with wax
• Indexed teeth to record the C.R. position should only be 11/2 –
2mm deep
• Using wax as the recording material, can not close through to CO
to see perforations of IPC

18. • Hand articulating them in MI (which is also CR for that patient)
If a patient’s maximum intercuspation is coincident with
their centric relation, what is the most accurate method of
mounting the casts in CR or MI?
• For a fully dentulous patient, you can not make an MI interocclusal
record.
So, if you are to mount casts in MI the most accurate method is hand articulating them
in the MI position

19. WE MARKED THE IPC
• and determined that the patient would sit
on the initial point of contact

20. THE CO INTEROCCLUSAL RECORDS WAS MADE
USING A PASTE MATERIAL
• that was plastic enough to offer little
resistance as the teeth passed
through it to reach and record CO
and the IPCs

21. TRIM INTEROCCLUSAL RECORDS
ICP
ADVANTAGE OF INTEROCCLUSAL RECORDS
MADE AT CO
• When the registration was removed from the mouth, the perforations at the initial
point of contact gave us immediate verification that we recorded the correct
mandibular position

22. PATIENTS THAT ARE DIFFICULT TO MANIPULATE
TO CR OR WILL NOT SIT ON THE IPC
• A deprogrammer may be fabricated that
• Creates a flat plane to contact a lower tooth or teeth
• Discludes the posterior teeth eliminating the feed back from
the mechanoreceptors
• Will open vertical
To that of C.O. Minimally
To vertical of the planned
appliance or restoration

23. THE INTEROCCLUSAL
RECORD IS MADE WITH THE
DEPRORAMMER IN PLACE
• But the deprogrammer is not transferred
to the casts for mounting

24. SETTING THE FOSSAE ELEMENTS
• Protrusive record - used to set the right and left
condylar guides
• Right lateral interocclusal record – used to set the left or
balancing side medial wall (PSS)
• Left lateral interocclusal record – used to set the right or
balancing side medial wall (PSS)

25. PRIOR TO SETTING THE FOSSA
ELEMENT ADJUSTMENTS:
• Set right and left condylar guides to 0 degrees
• Set right and left PSS adjustments to their
maximum

26. SETTING THE FOSSAE ELEMENTS
• Protrusive record - used to set the right and left
condylar guides
• Right lateral interocclusal record – used to set the left or
balancing side medial wall (PSS)
• Left lateral interocclusal record – used to set the right or
balancing side medial wall (PSS)

27. WHEN THE CASTS ARE INDEXED
INTO THE PROTRUSIVE RECORD:
• Both condyles will not be in contact with their back,
top, and medial walls
• Rotate the condylar guides until they touch their
respective condyles

28. WHAT DID WE DO? – MOUNTED IN CR

29. WHAT DID WE DO? – RECORDED A
PROTRUSIVE POSITION OF THE CONDYLES

30. WHAT DID WE DO? – RECORDED A
PROTRUSIVE POSITION OF THE CONDYLES

31. WHAT DID WE DO? – SET THE RIGHT AND
LEFT CONDYLAR GUIDES WITH PROTRUSIVE
RECORD

32. WHAT DID WE DO? – SIMULATED THE
CONDYLAR PATH ON THE ARTICULATOR

33. IS IT IMPORTANT THE CURVATURE OF THE
EMINENCIA IS NOT DUPLICATED?

34. THE POSTERIOR TEETH WILL SEPARATE
MORE IN THE MOUTH

35. BY THE RADIUS OF THE CURVATURE

36. SETTING THE FOSSAE ELEMENTS
• Protrusive record - used to set the right and left
condylar guides
• Right lateral interocclusal record – used to set the left or
balancing side medial wall (PSS)
• Left lateral interocclusal record – used to set the right or
balancing side medial wall (PSS)

37. WHEN THE CASTS ARE INDEXED
INTO A LATERAL RECORD:
• Neither condyle will be in contact with it’s respective
medial wall
• The balancing side medial wall will be set to contact
it’s condyle
• The working side condyle will be positioned away
from it’s medial wall – on the patient this is the
result of the sum total of their ISS and PSS

38. WHAT DID WE DO? - STARTED IN CR –
CONDYLES TOUCHING ALL THREE WALLS

39. RECORDED THE POSITION OF THE CONDYLES IN A
LATERAL MOVEMENT – ON ARTICULATOR, MEDIAL
WALLS SET TO THEIR MAXIMUM

40. BALANCING SIDE MEDIAL WALL ROTATED TO
TOUCH IT’S CONDYLE – WORKING SIDE CONDYLE
AWAY FROM IT’S MEDIAL WALL- AMOUNT OF SIDE
SHIFT

41. WITH I.O.RECORDS, DO NOT KNOW THE
PATH FROM CR TO LATERAL POSITION OF
CONDYLES – SUM TOTAL OF PATIENT’S ISS
& PSS

42. CRITERIA FOR PROPERLY MOUNTED
CASTS IN CR:
• IPC is the same as on the patient
• 2 of the 3 interocclusal records are interchangeable (if three
CR interocclusal records made)
• Direction and magnitude of the slide is the same as in the
patient
• Casts can be manipulated to MI with the same tooth
contacts as in the patient

43. WHY COULD A MOUNTING
BE INCORRECT?

44. NOT CHECKING ARTICULATOR TO SEE THAT
• There is no “play” between the upper and lower members of the
articulator
• The lower member travels back so the condyles meet their
respective back, top, and medial walls with no pressure being
applied
If these two criteria are not satisfied there is not a repeatable centric position of the
upper and lower members of the articulator

45. WHY COULD A MOUNTING BE
INCORRECT?
• Recorded incorrect position – patient not positioned to CR or did not stay in CR,
they slid forward on the IPC - CR record would have shown multiple perforations

46. • Average anatomic location of T.H.A. could be a factor
WHY COULD A MOUNTING BE
INCORRECT?
If CR record was made in
wax at an open vertical

47. WHY COULD A MOUNTING BE
INCORRECT?
• Average anatomic location of T.H.A. could be a factor

48. • Average anatomic location of T.H.A. could be a factor
WHY COULD A MOUNTING BE
INCORRECT?

49. • Average anatomic location of T.H.A. could be a factor
WHY COULD A MOUNTING BE
INCORRECT?
If the rotational center is not
the same as in the patient,
the arc of closure will be
different creating different
tooth contacts

50. This is why we recorded the centric relation jaw
position at CO
• Using a registration paste at C.O. with the IPC in contact
• Reason: eliminate possible error
due to closing on a less than
accurate rotational center because
the T.H.A. was found by it’s average
anatomic location to the external
auditory meatus
• Advantage: immediate verification
of C.R. record if IPC are the only
perforations in the record

51. WHY COULD A MOUNTING BE
INCORRECT?
• Casts not indexed correctly into interocclusal records
Casts are three months old - teeth
could have shifted

52. Properly trimmed interocclusal records allows the visual verification
that the casts are correctly indexed into the occlusal records.

53. WHY COULD A MOUNTING BE
INCORRECT?
• Mounting plate not indexed correctly on articulator frame
- Initially
- After removal and second addition of stone

54. WHY COULD A MOUNTING BE
INCORRECT?
• Condyles not properly seated in their fossae
- Fossae not tight against upper member
- Lower rocked on stone pulling condyles forward
Whip Mix Co.

55. INCISAL PIN ALWAYS SET TO TOUCH
INCISAL BLOCK/TABLE WHEN CASTS
ARE IN MI
• Casts in CR
- Condyles will be touching their back walls
- Incisal pin will not be touching the table, the space is the
relative amount of the vertical component of the CR slide
• Casts in MI
- Condyles will be away from their back walls, the space is the
horizontal component of the CR slide
- Incisal pin will be touching the table
Question – Will the incisal pin be at zero?
Answer – No. Why, it was set at zero with the casts were mounted in
CO so the vertical will be less when the casts slide to MI

56. EVEN IF DIAGNOSTIC CASTS WERE
MOUNTED IN CR
• If M.I. is determined to be physiologic and the restorative
procedures are to be completed in M.I., then working casts
are mounted in M.I. with the bite registration made on the
prepared teeth at the vertical at which the restorations are to
be fabricated with the remaining unprepared teeth in contact.

57. ASYMMETRIES OF THE JOINTS COMPARED TO THE
ARTICULATOR

58. Does the mandible rotate around the medial or lateral
pole?
Medial pole
Lateral pole
Rotation around medial pole Rotation around lateral pole

59. THE FACEBOW

60. • CR - Most retruded position of mandible
- RUM position of condyles
- Position determined by ligaments
- Terminal Hinge Position
- In CR, Mandible rotated around T.H.A.
- With tooth contact:
Retruded Contact Position = RCP
- CR arc of closure a boarder position – most retruded
• T.H.A - Most retuded (terminal) hinge axis
- Up to 20-25mm of pure rotational movement
- One axis of rotation
• CO - was MI
CONCEPTS REGARDING CR AND TERMINAL
HINGE AXIS PRIOR TO 1987

61. CONCEPTS REGARDING CR AND TERMINAL
HINGE AXIS PRIOR TO 1987
• THA - Verified by multiple CR records
made at different vertical
dimensions – condyles properly
seated and split casts traveling
correctly to place - if on actual
rotational center (THA) and CR
repeatable, then casts should
index correctly in all CR records
at different verticals
.

62. Split-cast mounting: a method of mounting casts wherein the dental
cast is sharply grooved and keyed to the mounting ring’s base. The
procedure allows verifying the accuracy of the mounting, ease of
removal and replacement of the casts GPT- 9

63. CONCEPTS REGARDING CR AND TERMINAL
HINGE AXIS PRIOR TO 1987
• CR - Verified by multiple CR records are
interchangeable

64. COMPARING CONCEPTS REGARDING CR AND
TERMINAL HINGE AXIS 1987 TO PRESENT
• Terminal Hinge Axis
Terminal hinge position =
CR
• Retruded contact position
• CO = MI
Prior to 1987
• Transverse Horizontal Axis
Terminal hinge position = CR
• Retruded contact position
• CO now CR with tooth
contact
After 1987 to present

65. COMPARING CONCEPTS REGARDING CR AND
TERMINAL HINGE AXIS
• Terminal Hinge Axis,
Terminal hinge position, CR, &
Retruded contact position
All RUM position of condyles
Prior to 1987

66. COMPARING CONCEPTS REGARDING CR AND
TERMINAL HINGE AXIS 1987 TO PRESENT
• Terminal Hinge Axis,
Terminal hinge position = CR,
Retruded contact position
All RUM position of condyles
Prior to 1987
After 1987 to present
• Transverse Horizontal Axis,
anterior superior position of
condyles contacting thinnest
avascular area of disc
Anterior to RCP & Terminal hinge
position

67. COMPARING CONCEPTS REGARDING CR AND
TERMINAL HINGE AXIS 1987 TO PRESENT
After 1987 to present
• CR not the most retruded
position of the mandibular
• Can still isolate rotation around
Transverse horizontal axis with
mandible in CR *
• CO - anterior and superior to
retruded contact position
• CR arch of closure anterior to
terminal hinge position but still
reproducible just not a boarder
position
• Trapozzano: J.P.D., 1961 – showed
this rotational center could
be located

68. ●
●
●
●
●
Denar
TSN (Thourp)
Lauritzen and Bodner
Beyron
Gysi
Prothero
● Brandrup- Wognsen
12 mm anterior to posterior border of tragas and 5mm inferior to line
extending from superior border of tragus to OCE
Bergstrom
●
Photo of face from ACP

69. DO NOT WANT TO CHANGE VERTICAL ON ARTICULATOR
• From vertical of interocclusal record to tooth contact
• Error of average anatomic location will occur in opening
eccentric movements
• RULE:
Diagnostic casts
Working casts
Always record jaw position as close to
vertical of the position to be evaluated or
vertical and position of appliance or
restoration to be fabricated

70. END