Horizantal jaw relations / dental courses

 Introduction
 Definition
 Significance of centric relation
 Retruding the mandible to centric relation
 Methods of recording centric relation
 Factors influencing centric relation record
 Interocclusal records

 Eccentric relation records
 Recording of eccentric jaw relations
 Review of Articles.
 Conclusion
 Bibliography.

INTRODUCTION
Horizontal relation are those that are established
anterio posteriorly & mediolaterally,
It is classified as
1, Centric relation
2, Eccentric relation- which includes
-Protrusive
-Left & Right lateral movements

The principles of good occlusion apply to both
dentulous & edentulous patients.
Different requirements are necessary in the
occlusion for the complete dentures because
artificial teeth are not attached to the bone as in
natural teeth.

To maintain stability of complete dentures,the
opposing teeth must meet evenly on both sides of
the dental arch when the teeth contact anywhere
within the normal functional range of mandibular
movements.

An occlusion for complete dentures that provides
these even contacts can only be developed with
centric occlusion in harmony with centric relation
& smooth gliding contact from this position to any
eccentric position with in the normal range of
mandibular movements.

DEFINITION
“The maxillo mandibular relationship in which the
condyles articulate with the thinnest avascular portion of their
respective discs with the complex in the anterior superior
position against the shapes of the articular eminences”
This position is independent of tooth contact and is
clinically discernible when the mandible is directed superiorly
and anteriorly. It is restricted to a purely rotary movement
about the transverse horizontal axis - GPT

Boucher defined as “The most posterior relation of
the lower jaw to upper jaw from which lateral
movements can be made at a given vertical
dimension”
Ramsfjord defined as “a clinically determined
position of mandible placing both condyles into
their anterior uppermost position. This can be
determined in patients without pain or
derangement in TMJ”

TWO DIMENSIONS OF CENTRIC RELATION-
DUAL CENTRIC
Centric relation should be understood as a
complex term with a condylar and mandibular
dimension. the condylar centeric position should
be differentiated from mandibular centric position.
1.condylar centric position - condyle disc fossa /
eminentia relationship
2. mandibular centric position – maxillomandibular
position
both these components of centric relation coexist
collectively known as centric relation

Significance of Centric Relation:
 It is a definite learned position which is
independent of the presence or absence of teeth.
 It is reproducible ,repeatable and
recordable position.

 When the centric relation & centric occlusion of
natural teeth do not coincide, the periodontal
structures around the natural teeth are endangered
 If the occlusion of artificial teeth do not coincide,
there is instability of the dentures leading to pain &
discomfort

RELATING CENTRIC RELATION TO THE
HINGE AXIS
During mandibular opening movement the
condyles rotate initially in a hinge and later in a
translatory motion.A pure hinge movement of the
condyle occurs only when the condyle is in its
centric position.

 Combinations of translation and hinge
movement take place when the condyle moves
anterior to centric relation.
Hence ,centric relation is known as the Terminal
hinge relation.

CHARACTER OF OCCLUSION IN
CENTRIC RELATION:
There are two concepts:
Point centric :
Long centric/ Freedom in centric / Area centric:

CONCEPTS AND OBJECTIVES IN
RECORDING CENTRIC RELATION:
1. minimal closing pressure
2. heavy closing pressure

RELATING CENTRIC RELATION TO
CENTRIC OCCLUSION:
 Centric relation is a bone to bone relation
 Centric occlusion is a relationship of upper
and lower teeth to each other.
 Centric relation must be accurately recorded
so that centric occlusion can be built to
coincide with it.

When natural teeth are removed,many
receptors that initiate impulses resulting in
positioning of mandible away from deflective
occlusal contacts into centric occlusion are lost or
destroyed.
Therefore edentulous patients cannot
control mandibular movements or avoid deflective
occlusal contacts in centric relation as in dentulous
patients.

These deflective occlusal contacts in centric
relation causes movement of the denture bases or
direct the mandible away from the centric
relation.
Thus centric relation must be recorded for
edentulous patients so that centric occlusion can
be established in harmony with this position.

Retruding the mandible to centric relation:
Difficulties seen are
 Biological
 Psychological
 Mechanical

Methods of assisting the patient to retrude the
mandible:
Instructing the patient to:
 Relax the jaw ,pull it back and close slowly and
easily on back teeth.[ never ask the patient to bite]
 Get the feeling of pushing your upper jaw out and
close your back teeth together.

 Protrude and retrude the
mandible repeatedly as the
patient holds the fingers
lightly against the chin.
 Turn the tongue backwards
towards the posterior border
of the upper denture.
 Ask the patient to swallow &
conclude the act with the
blocks in contact.

 Assist the patient to retrude
the mandible by placing the
index fingers on the buccal
flanges on the premolar
regions with the thumbs
under the patients chin.

Factors Influencing Centric Relation Records
 The resiliency of the supporting tissue.
 The stability of the recording bases.
 The TMJ and its associated neuromuscular
mechanism.
 The nature of pressure applied in making the
recording.

 The technique in making the recording & the
associated recording devices used
 The skill of the dentist.
 The health & the co-operation of the patient.
 The maxillomandibular relationship

Primary Requirements for Making Centric
Relation Records
 To record the correct horizontal relationship of
the mandible to the maxilla.
 To exert equalized vertical pressure.
 To retain the record in an undistorted condition
until the cast has been accurately mounted on the
articulator.

Methods Of Recording Centric Relation:
 Physiological / tactile / interocclusal check
record method.
 Functional/ chew in method.
-Patterson technique
-Needle house technique
 Graphic method.
-Intra oral tracing
-Extra oral tracing

Physiological / tactile / interocclusal check
record method:
History
 In 1756,Philip pfaff, the dentist of Frederick the
great of Germany, was the first to describe this
technique.
 The direct interocclusal record during that period
was a non-precision jaw record obtained with a
thermoplastic material, usually wax or compound.
 This was known as “mush” “biscuit” or “squash
bite.

 Hanau[1929] was the first individual to be
concerned about equalization of pressure when
recording the bite. He coined the word “realeff”
which is formed by the beginning letters of the
words “resilient and like effect”.
 This became a major factor in “check bite”
techniques.

 Schuyler[1932] preferred modelling compound
to wax for the occlusal records
 Wright (1939) described the four factors which
affected the accuracy of records-
1. Resiliency of tissues.
2. TMJ & neuromuscular control
3. Fit of bases
4. Pressure applied

 Payne[1955] & Hickey[1964] stated a preference
for plaster
 Trappzzano[1955] stated that wax check bite
method was the technique of preference
 Boos[1959] stated that it was important to avoid
torsion when recording centric relation & felt that
plaster & zinc oxide eugenol paste was more
accurate

 Scyhyler, Payne and Trapozzano advocated the
use of light pressure
 The problem of pressure in any record was
recognized by Boucher (1960) who wrote,
“In addition to technical errors are the
errors which occur as a result of failure to
control jaw activities and pressure at the time of
registration”.

Interocclusal records
1. Impression compound
2. Wax
3. Zinc oxide eugenol paste
4. Impression plaster
5. Bite registration paste

Methods of sealing record blocks together
1. Heat
2. Nick and notch
3. pinning

Physiological / Tactile / Interocclusal Check
Record Method:
It is particularly indicated in situation of
 Abnormally related jaws
 Supporting tissues that are excessively
displaceable
 Large tongue.
 Uncontrollable or abnormal mandibular
movements
 To check the occlusion of the teeth in try-in
dentures

The technique for this record is divided into two
steps-
1. Tentative records using occlusion rims attached
to accurate stable bases.
2. Inter occlusal check records with teeth arranged
for try-in.

Nick and notch method:
 Nick and notch are cut
on the maxillary occlusal
rim and a trough on the
mandibular rim.
 Interocclusal record
material is placed on
the troughs created on
mandibular occlusal rim.

 Patients is asked to close in centric relation.After the
material is set,occlusal rims are removed and
articulated.
 In this method, the final centric relation is recorded
after establishing a proper vertical jaw relation.

Verification of Centric Relation
Wax check bite record
Palpating the temporalis and the masseter
muscles.
Use of guide lines on the occlusion rims

Functional/chew in Method :
HISTORY
 Functional recordings were described as early as
1910 by Greene where he used a pumices and
plaster mixture in one of the rims and instructed
the patient to grind the rims together. The teeth
were set to the generated paths.

 Needles(1923) mounted studs on the maxillary
rims which cut tracing into the mandibular rims
 Petterson(1923) used a carborundum and plaster
mixture which were filled in a trough cut in the
upper and lower rims
 Meyers(1934) used soft wax occlusion rims.

 Boos (1959) felt that it was essential that all
registrations be made under the biting force so
that the displacement of the soft tissues which
occur in function would occur during bite
registration

Functional/chew in Method ::
Needles-house technique:
 Compound occlusal rims
with 4 metal styli placed
in the maxillary rim.
 When the mandible moves
with the styli contacting the
mandibular rim , the styli
cuts 4 diamond shaped
tracings.

 The pathways cut into the
modeling compound indicate
both the centric position and the
eccentric mandibular
excursions.
 The records are placed on a
suitable articulator to receive
and duplicate the records.

Disadvantages
1. The displaceable basal tissues, the resistance of
the recording medium and the lack of control of
equalized pressure in the eccentric relation
contribute to inaccuracies.
2. Patients should have a good neuromuscular co-
ordination and should be capable of following
instructions.

The Patterson method:
 Uses wax occlusal rims.
 A trench is made in the
mandibular rim and a
mixture of half pumice
and half carborundum
paste is placed in the trench.

 When the pumice and carborundum are reduced to
the pre determined height the patient is asked to
retrude the mandible and the occlusion rims are
joined with metal staple pins.`

NEEDLE POINT TRACING:
HISTORY
• The earliest graphic recording Were based on
mandibular movements by Blackwill in 1866.
The intersections of the arcs produced by the
right and left condyles formed the apex of what is
known as the “Gothic arch tracing”.
• The first known”Needle point tracing” was by
Hesse in 1897, and the technique was improved
and popularized by Gysi around 1910”

• Gysi’s tracer was an Extraoral incisal tracer in
which the plate was attached to the mandibular
rim & spring loaded pin was mounted on the
maxillary rim.

 Phillips(1927) recognized that any lateral
movement of the jaw would cause interference of
the rims resulting in a distorted record.
 He developed a plate for the upper rim under
tripoded ball bearing mounted on a jack screw for
the lower rim. The innovation was named the
“Central bearing point”, which was supposed to
produce the equalization of pressure on the
edentulous ridges.

 Stansbery (1929) introduced a technique which
incorporated a curved plate corresponding to
monson’s curve.
 He mounted this on the upper ring and a central
bearing screw was attached to a lower plate
corresponding to the reverse monsoon curve.
After the tracing was made , a biconcave centric
registration was obtained using plaster.

 Later gothic recording methods used the central
bearing point to produce gothic arch tracing.
Various tracing devices were designed by hight,
Phillips, Terrell, Sears, House, Messerman and
others

 The graphic recording like the check bites
records received much praise and criticism.
Critics of Gothic arch tracing stated that
equalization of pressure did not occur,
prognathic and retrognathic patients could not be
used, flabby tissues and large tongues could
cause shifting of the bases and finally too much
of patient cooperation was needed.

Graphic Methods:
Graphic methods are of two types:
 Arrow point tracing.
- Extra oral tracing.
- Intra oral tracing.

• Earliest graphic recordings were based on mandibular
movements by balkwill in 1866
• First known needle point tracing was done by hesse in
1897
• needle point tracing was improved and popularised by gysi
in 1910
• Clapp 1914 used gysi tracer attached directly to impression
trays

• Sears 1926 attached needle point to
mandibular
• Philips 1927 recognised that any lateral
movement causes interferences of rims
which could distort the record. He
developed plate for upper rim and ball
bearing screw on lower rim

Extra Oral Tracing Assembly
 It has a central bearing device consisting of a central
bearing point & a plate
 It has a tracing device consisting of a stylus & a
recording plate

Hight extra oral tracer assembly Sears extra oral tracer assembly
Swissdent ball bearing bite recorder Microtracer for intra oral use

 When the patient is
proficient in executing the
mandibular movements
prepare the tracing plate to
record the tracing by coating
with thin coat of precipitated
chalk in denatured alcohol.
 Develop an acceptable
tracing by dropping the stylus
to the record plate.

 When a definite arrow point tracing
with a sharp apex is made, have the
patient retrude the mandible to the
centric relation.
 Inject quick setting dental plaster
between the occlusion rims.
 Remove the assembly and mount the
mandibular cast with the new record.

ADVANTAGES
 Tracing point is much larger because they are
made farther from the centers of rotation & the
apex is more discernible
 Extra oral tracings are visible when the tracings
are made, therefore patients can be guided &
directed more intelligently

 The stylus can be observed in the apex of the
tracing during the process of injecting plaster
between the occlusal rims & no hole is required.

Extra oral tracers
1. Hight tracer
2. Sears tracer
3. Philips tracer

Intraoral tracers
• Coble tracersd
• Swissdent ball bearing
• Micro tracer

Classical, pointed form
The symmetry indicates an
undisturbed movement sequence in
the joints and uniform muscle
guidance. Gothic arch angle is about
120 degrees
Evaluation of Gothic Arch Tracings:
Classical flat form
Indicates distinct lateral movements
of the condyles in the fossa. More
than 120 degrees

• Blunt apex indicates acquired functional
relationship
• Double tracing lack of coordinated
movements or recordings at different
vertical dimension

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 movement on one side of joint.

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.

Double arrow point – habitual and also seen when
vertical dimension is altered
Interupted gothic arch – posterior interference at
heels of occlusal rims during lateral movements
Atypical form - bruxism

Intra-oral tracing devices
 It is a combination of a central – bearing point and
plate with a needle point tracing made inside the
mouth.
 The bearing point is sharp which makes a tracing
on the opposing central bearing plate .

A hole may be drilled at the apex of the
tracing to ensure that the patients jaw is in the
most retruded position while the registration is
being recorded.
A plastic piece with a hole in the center can
also be placed at the apex.

DISADVANTAGES
 Tracings are small, hence its difficult to find the
apex.
 The tracer must be seated in the hole at the point
of the apex to assure accuracy when injecting
plaster between the occlusion rims.
 If the patient moves the rims before they are
secured, the records shift on their basal seat
which destroys the accuracy.

Williamson,Bowley and Randy :
Mandibular denture base stability
has been reported to be increased by using an
central bearing intra oral gothic arch tracing
device,as it provides equalization of occlusal
pressure.

Other methods of recording centric relation:
 Strips of celluloid placed between the rims
 Heating the surface of one of the rims
 Softened wax placed over the occlusal surface of
the mandibular posterior teeth
 Soft cones of wax placed on the lower denture
bases

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

Eccentric relation records
 An eccentric maxillo-mandibular relation is any
relationship of the mandible to the maxillae other
than the centric relation.
 It is recorded to adjust the lateral and horizontal
condylar inclinations.

 The adjustment permits the condylar elements to
travel to and from the centric and eccentric
positions and make it possible to arrange the
teeth for complete dentures in balanced
occlusion.
 The eccentric positions to be recorded are the
protrusive and the right & left lateral.

Tactile or Inter Occlusal Check Record
 The preferred time to make the record is during
the try-in procedure
 The trial dentures are inserted & the patient is
instructed to protrude his lower jaw to
approximately 5-6 mm
 Midline of maxillary & mandibular incisors
should coincide

 Once the patient has learned this position, 3
layers of wax is placed over the mandibular teeth,
seal the wax on the lingual & buccal surface of
the teeth.
 The wax is softened over the controlled water
bath.

 Try-in dentures are re-inserted & the lower jaw is
protruded until the upper teeth contact the wax.
 The wax is allowed to harden and transferred to
the articulator to record the horizontal inclination.

Recording of eccentric jaw relations:
Gothic arch tracing :
(protrusive relation records)
 Measure a distance of 5 to 6 mm from the apex
of the arrow point tracing on the protrusive
tracing and mark this point
 Instruct the patient to protrude until the point of
the stylus rests in the marked point

 Inject quick setting dental plaster between the
occlusal rims.
 Free the horizontal condylar adjustment on the
articulator.
 Raise the incisal pin about one half inch from the
top of the guide table.
 Carefully seat the record bases on the cast.

 Using the locknuts as handles manipulate one
side ,then the other.
 An accurate seating of both record bases must be
secured without forcing so that the protrusive
record is not destroyed.
 Secure the lock nuts.

Lateral relation records :
Gothic arch tracing:
 Two records are required – one of right lateral and
one of left lateral
 The articulator is adjusted as each record is made.
 However with complete dentures, it is more
difficult to secure accurate & reproducible
records.

 Hanau recommended a formula to arrive an
acceptable lateral inclination
L =H/8+12
L- Lateral condylar guidance
H- Horizontal condylar inclination in
degrees as established by the protrusive record
 The value of this formula is neither proved or
disproved

Atwood, D.A. A critique of research of the posterior limit of the mandibular position. J Prosthet Dent 20:21-36, 1968.
Review of literature
Atwood,D.A.Acritique ofresearchoftheposterior limitofthemandibularposition.J ProsthetDent20:21-36,
1968.
PosteriorlimitofthemandibleatVDOisestablishedbystructuresanteriorandlateraltothecondylesrather
thanposteriortothem.(lateralpterygoid andtemporomandibularligament)Thetemporomandibularligaments
contain proprioceptivenerveendingssusceptibletostretchingleadingtoinhibitionoftheretrusive
muscles(temporalisanddigastrics),andstimulationoftheprotrusiveantagonistmuscles(lateralpterygoids).

1.Inbiomechanicaltermsthecentricrelationisanonfunctionalposition.
2.Overrelativelylongperiodsoftime,themorphologyofallfunctionalsurfacesoftheTMJiscapableof
significantadaptivealterations.Theseare normalcompensatory responsesofskeletalunitstotheprioralterationsof
functionalmatrices.
3.Inmuchshortertimeperiods,thedynamicallyfluctuantstateoftheneuromuscularapparatusmakesitreasonably
certainthatintra-individualvariationincondylarpositionscanexist.
A functional cranial analysis of centric relation.
DCNA 19:431-442, 1975.

Clinicalimplicationsofmandibularrepositioning andtheconceptofanalterablecentricrelation.
DCNA19:543-570,1975.
Temporomandibulararticulationhasawiderangeofadaptabilityandremodelingcapacity.Thejointsassumetheir
positionasaresultofinterplayofintercuspationofteeth,jawsandneuromusculature.Adynamicconceptofcentric
relationispresentedasaquasi-fixedpositionoftemporary durationwhichexistsinastateofequilibriumestablished
bytheneuromusculatureandligaments.Adoptionofthisconceptallowsforadiagnosisandtreatmentwhichis
rationalintheoryandworkableinfact.

• ShafaghI,YoderJL,ThayerKE.Diurnalvarianceofcentricrelationposition.JProsthetDent34:574-582,
1975.
• 1.Centricrelation wasrepeatableforafewpatientsbutinmosttherewasvariation.Thegreatestvariationwasinthe
superoinferiordirection.
2.Inmanypatientsthecondyleswere intheirmostanteroinferiorpositioninthemorningandintheirmost
superoposteriorpositionintheevening.Thismayindicatethatthere isadiurnalpatterninthepositionofcentric
relationpossiblyrelated tofluid contentinthejoint.

3.Dependingonone'sdefinitionofcentricrelation,onetimeofdaymaybe favored overanotherduetodiurnalbias.If
themostretrudedandsuperiorpositionofthecondylesisdesired,theeveningseemstobeabettertimeformaking
CRrecords.
4.Freedomtomovetosomedegreearoundaclinicallydeterminedcentricrelationpositionmayhavemeritasa
treatmentphilosophy.

Serrano,P.T.andNicholls,J.I. CentricRelationChangeDuringTherapywithOcclusalProstheses.JProsthetDent51:97-
105,1984.
1.Correctiveocclusionprosthesistherapydidnotimprovethereproducibilityofcentricrelationin asymptomaticpatients.
2.Centricrelation isnotonepositionbutisarange ofpositions.
3.TherangeofCRvariationisgreaterlaterallythanantero-posteriorly

Conclusion
The accurate determination,recording
& transfer of jaw relation records from the
edentulous patient to the articulator is essential
for the restoration of function,facial appearance
and the maintenance of patient health.

 Therefore it is emphasized that irrespective of the
method used, subsequent clinical checking and
rechecking must be done throughout the entire
denture construction phases.
 The skill of the dentist & the co-operation of the
patient being most important factor.

References
1.Complete denture prosthetics- john p sharry
2.Essentials of complete denture- sheldon winkler
3.Syallabus for complete dentures – charles heartwell
4.Treatment planning for completely edentulous – boucher
5.Fundamentalsofocclusionand temporomandibulardisorders-JefferyP.Okeson
6.Acritiqueofresearchoftheposteriorlimitofthemandibularposition.JProsthetDent20:21-36,1968.
7.Afunctionalcranialanalysisofcentricrelation.DCNA19:431-442,1975.

8.Clinicalimplicationsofmandibularrepositioningandtheconceptofan alterablecentricrelation.DCNA19:543-570,
1975.
9.Areviewofsomeproblemsassociatedwithcentricrelation.JProsthetDent2:307-319,1952.
10.Diurnalvarianceofcentricrelationposition.JProsthetDent34:574-582,1975.
11.CentricRelationChangeDuringTherapywithOcclusalProstheses.JProsthetDent51:97-105,1984.
12.centric relationrecordsreview.Jprosthetdent1982 feb;47;141.
13.factorsinfluencing centricrelationrecordsinedentulousmouths.
Jprosthetdent2005;93;305

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