Interocclusal records and mounting of casts on articulator/ online orthodontic courses

Interocclusal records andInterocclusal records and
mounting of casts on articulatormounting of casts on articulator
1
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Contents
 Introduction
 Techniques
 Types
 Materials
 Mounting of casts on articulators
 Conclusion
 References
2www.indiandentalacademy.com

Introduction
 The tactile or inter occlusal check record is
referred to as physiological method.The
kinesthetic sense or muscle sense helps to direct
movements of parts of body through space.
 It is one of the methods of recording centric
relation . It is particularly indicated in situations
of abnormally related jaws , supporting tissues
that are excessively displaceable , large tongues ,
& uncontrollable or abnormal mandibular
movements. It is also used to check occlusion in
existing dentures & in trial dentures .

Types of inter occlusal records
Centric inter occlusal records
Eccentric inter occlusal records
lateral inter occlusal records
protrusive inter occlusal records

Definitions
 Inter occlusal record : registration of the
positional relationship of the opposing teeth or
arches
 A record of the positional relationship of the
teeth or jaws to each other.
 Centric inter occlusal record-a record of centric
jaw position
 Eccentric inter occlusal record – a record of jaw
position other than centric
 Lateral –record of lateral eccentric jaw position
 Protrusive – record of protruded eccentric jaw
position . 5www.indiandentalacademy.com

Factors that influence inter
occlusal records
 Amount and equalization of pressure , which
depends on uniform consistency of recording
material .
 Comfort of patient ,which depends on stability
& compatibility of record bases. Artificial teeth
are more compatible to mandibular movements
than occlusion rims.
 An inter occlusal record with multiple points of
references made by styli or cusp tips is more
satisfactory than with occluding surfaces of wax
or non cusp form teeth.

Techniques
 Active techniques
 Passive techniques

Methods of assisting the patient
to retrude the mandible
1)instructing the patient to:
 let your jaw relax ,pull it back and close
slowly and easily on your back teeth
 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
 Tap the opcclusal rims or the back teeth
repeatedly
 Tilting the head back while all the exercise
is carried out
 Palpating the temporal and the masseter
muscles to relax them

Clinically accepted methods
 One hand chin point guidance technique
 Dawson’s technique
 Unguided technique
 Tongue to palate technique

 Dawson’s technique

 One hand chin point guidance technique

Unguided technique
 Lucia jig
 leaf gauge
 Central bearing point
 Cotton roll

Tongue to palate technique

Characteristics of ideal registration
material
 Limited resistance before setting to avoid
displacing teeth or mandible during closure.
 Rigid after setting
 Minimum dimensional change
 Accurate record of incisal & occlusal surfaces
 Easy to manipulate
 No adverse effect on tissue
 Records should be verifiable

Materials
 Impression plaster
 zinc oxide eugenol
 waxes
 elastomers
 acrylic resins
 Impression compound

Impression plaster (soluble plaster)
 Type 1 modified with addition of
accelerators to decrease setting time &
setting expansion
 Records are accurate , rigid after setting ,
do not distort with extended storage ,
 Difficult to handle , record is brittle .

Bite registration waxes
 Ease of manipulation ,
 Inaccurate ,unstable ,inconsistent , may
interfere with active & passive movements

Zinc oxide eugenol paste
 Fluidity before setting – is a critical factor
because it ensures minimal interferences with
mandibular closure during recording .
 Adhesion to carriers
 Rigid and inelastic after setting
 Accuracy in recording occlusal and incisal
surfaces
 High degree of reproducibility

 Brittle(vital portion may be lost by
breakage)
 Sticks to tissues
 Unless trimmed ,flash around the teeth
may prevent accurate seating of casts

Silicone elastomers
Addition and condensation silicones
 Good accuracy.stable after
setting,minimum resistance to closure
Resistance to compression of set material
which contributes to difficulty of seating of
plaster casts

Polyether material
 Accurate,stable to store,good fluidity,and
minimum resistance to closure .
Self curing acrylic resins
 Good fluidity , but brittle , generates heat while
setting , distortion & very hard on dies.

Impression compound type I
uneven softening of material,distortion and
inability to reproduce details accurately.

 Three general classes of records are used
to transfer maxillo mandibular relation ship
from patient to articulator
 Inter occlusal records
 Graphic records
 Hinge axis records

Inter occlusal record adjustment
 The mechanical features that determine whether
an articulator can be adjusted to accommodate
inter occlusal records include
 Individually adjustable horizontal condylar
guidance's
 Variable controls for bennet shift
 Variable inter condylar distances
 Split axis condylar guidance controls
 Adjustable incisal guidance control

Requirements of centric relation
record
 At open vertical dimension a face bow is indicated to
orient maxilla to upper member of articulator
 The inter occlusal registration material must be
passive so that it does not interfere with clinical
positioning of mandible
 Centric relation registration must be repeatable and
recordable

 Patient must be able to make eccentric
mandibular movements from centric
relation registration
 Patient can voluntarily and reflexly return
to this position
 The record should be verifiable

Technique for inter occlusal record is divided
into 2 steps
 Tentative record using occlusion rims
attached to accurate stable record bases
 Inter occlusal check record with teeth
arranged for try in

Technique
 Seat the patient comfortably with head
upright
 Contour the maxillary rim ,lip line,occlusal
plane and place notch to aid in seating
records (trial denture when used the record
material is sealed to lower posterior teeth)
 Establish the vertical dimension of jaw
separation with mandible at rest .

 Reduce the mandibular occlusal rim to
allow inter occlusal distance
 Make face bow record
 Using interocclusal record material make
tentative centric relation record

 Adjust condylar elements and secure them
against centric stops
 Mount the maxillary casts using face bow
record
 Secure the centric relation record and
position the mandibular cast
 Attach the cast to articulator with plaster

Eccentric interocclusal record
– The purpose is to adjust horizontal & lateral
condylar inclinations so that articulator jaw
members perform eccentric jaw movements
equivalent to the relative movements of the
mandible
– These adjustments provide condylar elements
to travel to & from centric & eccentric
position & make it possible to arrange teeth in
balanced articulation

Protrusive relation record
Seat the patient in comfortable upright position &
rehearse the patient to protrusive bite
Instruct the patient to protrude the lower jaw for
approx 5-6 mm from centric observe the midline.
Reinsert the trail denture and instruct the patient
to protrude the jaw and close until the upper teeth
contact the record material
Allow the interocclusal record material to set . .
Set the condylar post of articulator on 0 degree
on the lateral calibrations

 Release the horizontal condylar adjustments by
freeing the lock nuts .raise the incisal guide pin one
half from incisal guide table.
 Place the maxillary and mandibular trial dentures in
their respective mounting casts in their articulator,
carefully relate the maxillary teeth to interocclusal
protrusive records
 examine condylar elements to see protrusion is 5- 6
mm.
 Using horizontal condylar lock nuts as handles
manipulate one side and then another until all the
teeth are accurately seated in record.
 Secure the horizontal condylar adjustment locknuts
with finger pressure 38www.indiandentalacademy.com

Lateral interocclusal records
 When an articulator accurately adjusts to lateral
maxillo mandibular records the additional points
of reference are valuable
 The more accurate points of references supplied
in adjusting the articulator the more harmony
will exist between mandibular movements and
cusp inclines
 The record is made in the same manner as the
protrusive record. Two records are required one
of right lateral and one of left lateral.
 The articulator is adjusted as each record is made 39www.indiandentalacademy.com

 Although the mechanics of making the lateral
jaw relations records appears simple it is
recognized that in complete denture
construction the procedure is difficult and
many inaccuracies occur
 Hanau held the opinion that the setting of
lateral inclinations by an an anatomic record
offers no particular advantages and the
requirements can be determined on the
finished case in the mouth by the records ,
observations and interpretation of symptoms
on ridges.

Hanau’s formula for lateral
inclination
L = H/8 +12
 L = Lateral condyle inclination in degrees
 H = horizontal condyle inclination in
degrees as established by the protrusive
relation record

Review of literature
Fattore et al (1984 JPD) studied accuracy of
waxes ,zinc oxide eugenol & polyether and found
that
 Polyether recording material was the most
accurate, with out carrier.
 Polyether and zinc oxide eugenol paste were
second most accurate with carrier .
 Recording waxes ware consistently unreliable.
 Distortion occurs more frequently in a vertical
direction , followed by an anterior posterior
direction.

Millestien (1985 JPD)studied accuracy of laminated
wax interocclusal record (aluminum foil
laminated between layer of wax )combined with
use of dental plaster to mount casts and
concluded that
 Plaster which is most commonly used to mount
casts expands and then contracts to 0.30%.
 Wax was inaccurate material even if mounting
was precise .

Michael urstein et al (1991JPD)studied 3 recording
materials wax , plaster , and resin in maximum
intercuspation position (IC) and retruded contact
position (RCP) and concluded
 Where a complete or nearly complete dentition is
present and occlusion is stable hand articulation
is most accurate method.
 Plaster is more accurate material in recording IC
and RCP ,than either wax or resin.
 Wax record is slightly more accurate than resin at
IC position and RCP. 44www.indiandentalacademy.com

Vergos .v.k et al(Int.JP. 2003) studied 4 inter
occlusal record materials
 polyether, polyvinyl siloxane,acrylic,wax, to
record and maintain vertical relation.
 Their results showed least dimensional change
with poly vinyl siloxane followed by poly ether
and wax showed highest dimensional change.
 which ever material used for recording, 0.5mm
vertical discrepancies occurred when records
were transferred on casts which were clinically
significant. 45www.indiandentalacademy.com

Conclusion
The accuracy of inter occlusal records is
single most important factor in complete
denture construction.
Articulators are not used to their full
capabilities,its functions should be within
the understanding of the operator. It can
perform no better than the accuracy of the
inter occlusal record used.

BIBLIOGRAPHY
 Prosthodontic treatment for edentulousProsthodontic treatment for edentulous
patient-(8patient-(8th,th,
1111thth
, 12, 12thth
,),)
BoucherBoucher
 Syllabus of Complete Denture-Syllabus of Complete Denture-
HartwellHartwell
 Essentials of complete denture-Essentials of complete denture-
WinklerWinkler
 Complete Denture Prosthodontics
John J SharryJohn J Sharry 47www.indiandentalacademy.com

 Evaluation,diagnosis,and Treatment of
Occlusal Problems - Peter E Dawson
 Management of temperomandibular
disorders and occlusion 4th
edition
- Jeffery P Okeson
 The Glossary of Prosthodontic Terms 7th
Edition
- The Academy of Prosthodontics

49
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