Jaw relatios in rpd / orthodontic straight wire technique

JAW RELATIONS IN REMOVABLE PARTIAL
DENTURE
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

CONTENTS
 Introduction
 Definition
 Bite registration materials
 Methods of establishing maxillomandibular relations
 Jaw relations for a mandibular partial denture opposing a
maxillary complete denture
 Fixed partial denture against removable partial denture
 Materials used for occlusal surfaces of artificial posterior
teeth
 Conclusion
 References www.indiandentalacademy.com

INTRODUCTION
Balanced occlusion is desirable in complete denture
because unbalanced occlusal stresses may cause instability
of denture.
In removable partial denture because of attachment
of RPD to abutment teeth , occlusal stresses can be
transmitted directly to abutment teeth resulting in sustained
stresses that may be more damaging.

Failure to provide and maintain adequate occlusion on the RPD
is primarly a result of :
1. Lack of support for the denture base
2. The fallacy of establishing occlusion to single static jaw
relation record
3. An unacceptale occlusal plane

OCCLUSAL REGISTRATION
A registration of the positional relationship of apposing
teeth or arches to each other - GPT

OBJECTIVES:
1. To establish & maintain a harmonious relationship with all
oral structures & to provide a masticatory apparatus which is
efficient, comfortable & esthetically pleasing.
2. Distribution of functional forces evenly as possible to all
supporting structures within their capability of withstanding
the stress.
3. A harmonious occlusion contributes materially to the control
of damaging, leverage induced stresses where as a faulty
occlusion compounds the destructive forces.

JAW RELATIONS
1. Vertical jaw relations
2. Horizantal jaw relations
3. Orientation jaw relations

VERTICAL JAW RELATIONS

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.
HORIZANTAL JAW RELATIONS

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.

 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.

IDEAL REQUIREMENTS OF BITE REGISTRATION
MATERIAL
1. Limited resistance before setting to avoid displacing the
teeth or mandible during closure.
2. Rigid after setting.
3. Minimal dimensional change after setting.
4. accurate recording of occlusal & incisal surface of the teeth.
5. Easy to manipulate.
6. No adverse effects on the tissues involved in recording
procedures.
7. Interocclusal record should be verifiable.

 Wax
 Impression plaster
 Zoe imp paste
 Elastomers
 Acrylic resins

William F.malone and associates conducted a study to compare
the clinical accuracy of various inter occlusal recording
materials
they compared
1. Two thickness base plate wax
2. Reinforced wax
3. Zinc -oxide eugenol paste
4. A modified ,non rigid poly ether recording medium with a
carrier
5. Poly ether without a carrier

they concluded that:
 Polyether inter occlusal recording medium without a carrier
was the most accurate
 Polyether and Zinc -oxide eugenol paste with carriers were
the next most accurate recording mediums.
 Recording waxes were consistently unreliable.

RECORDING OF OCCLUSAL RELATIONSHIP
It may vary from simple apposition of the apposing
casts by occluding sufficient remaining natural teeth to
recording of jaw relationship in the same manner as for a
completely edentulous patient.

METHODS OF RECORDING OCCLUSION
1. Direct apposition of casts.
2. Interocclusal records with posterior teeth remaining.
3. Occlusal relation using occlusal rims on record bases.
4. Jaw relation made entirely on occlusion rims.
5. Establishing occlusion by recording of occlusal pathways.

DIRECT APPOSITION OF CASTS
Also known as “HAND ARTICULATION”
Coined by KROGH POULSEN.

INDICATIONS

1. wooden sticks
2. wire nails
3. sticky wax .

ADVANTAGES:
1. Though there are limitation, yet it is better than using an
inaccurate record between the remaining natural teeth.
2. It eliminates the clinical appointment.
3. It eliminates the possibility of the patient giving a faulty
jaw relationship

LIMITATIONS
1. The principle danger is this method may perpetuate the
existing vertical dimension and any existing occlusal
disharmony.
2. So occlusal analysis and correction of any occlusal
disharmony should precede the accepting of such a jaw
relation.

INTEROCCLUSAL RECORDS WITH POSTERIOR
TEETH REMAINING
INDICATION:
It is the modification of the first method and is used
when sufficient teeth remain to support the partial denture
(Kennedy class III or class IV).

PROCEDURE

The wax is removed and
chilled thoroughly. It is
again replaced in mouth to
correct the distortion and
chilled again.

 The wax record should be further corrected with a bite
registration paste to obtain a more accurate and dimensionally
stable record.
 For this procedure the opposing surface of teeth is coated with
petroleum jelly for ease of removal of record.

The impression paste is
applied to both the side of
the wax record and the
patient is assisted to close
in centric relation guided
by the wax record.

After the paste is set, the
record is removed and
excess is trimmed off.

Record is secured to the
maxillary cast and then
mounted in an articulator.

ADVANTAGES
1. Provides an accurate interocclusal record.
2. If an intact opposing arch is present stone can be directly
poured into the record to serve as a opposing cast.

OCCLUSAL RELATIONSHIPS USING OCCLUSAL RIMS
ON RECORD BASES
INDICATION:
1. When edentulous space is long.
2. When opposing teeth do not meet.

When one or more distal extension areas are present.

PROCEDURE
Accurate records bases are to be used to support the
occlusal relationship.

RECORD BASES
Acrylic resin
1. self cure
sprinkling method
dough method
2. heat cure

 Completed record is
examined and it is trimmed
so that only cusp tips and
indices remain. Cast are
then mounted on the
articulator by using the
record.

JAW RELATION RECORDS MADE ENTIRELY ON
OCCLUSAL RIMS
 When no occlusal contact exists between the teeth, such as
when opposing maxillary complete denture is to be made
concurrently with a mandibular partial denture.

 When few remaining teeth
do not occlude and will not
influence eccentric jaw
movement.
 When only anterior teeth is
present

PROCEDURE
1. Stable record bases and rims are required.
2. Vertical dimension at rest and at occlusion is established by
means of NISWONGER’s
3. Centric relationship can be established by direct interocclusal
method or by stylus tracing is used.

 Facebow transfer is made and the casts are mounted on a
semi adjustable articulator.
 Eccentric records such as protrusive and lateral records are
made.
 Articulator is programmed to simulate natural movements of
the lower jaw. Desired occlusion is obtained.

ADVANTAGES
1. Better method when the prosthesis is opposed by a
completely edentulous arch.
2. Does not require patient co-operation as that needed for
generating functional pathway.

LIMITATION
Skill and care is necessary to obtain the intraoral records,
accuracy and thoroughness with which they are used to
program the instrument.

ESTABLISHING OCCLUSION BY RECORDING OF
OCCLUSAL PATHWAYS
FUNCTIONALLY GENERATED PATH METHOD.
It is a dynamic record of movement of opposing tooth surface.

Theory:
when the pathways each tooth opposed to the edentulous
space makes throughout all functional movements of the
mandible are recorded, the artificial teeth may thus be
positioned and formed so that it will remain in harmonious
contact with its antagonist all the times.

CLINICAL PROCEDURE
Stable acrylic resin record base with hard inlay wax (purple)
can be used to record the occlusal pathways.

Occlusal rims is constructed
slightly higher than the
occlusal plane so that the
natural teeth are apart by
0.5 to 0.75mm.

There are two methods of having the patient grind the occlusal
pathways.
First method : the patient is instructed to wear the occlusal rims
continuously for 24 hrs except when eating and drinking hot
or chilled drinks.
He should be told to close the jaws intermittently and grind the
wax in all possible jaw position.

 The patient is asked to wear the prosthesis overnight so that
any involuntary or bruxism contacts can be recorded
 The resulting pathway will record of all possible jaw
movements and tooth contacts.

Second method: is for the patient to create the pathway directly
under the supervision of the dentist.
Advantage: dentist is able to observe and correct the movement
the patient is making.
Disadvantage: atleast 30min of active movement of the mandible
is necessary.

 The wax pattern is boxed
and poured in improved
stone to provide
permanent record of the
generated pathways.

 The stone record is
mounted on a articulator
and the artificial teeth are
set to contact the record.

 The incisal pin is opened 1mm before the artificial teeth are
positioned. This increase in vertical dimension will be
returned to normal by selective grinding of the teeth.
 The selective grinding develops occlusal anatomy of the
denture teeth to conform to the functionally generated stone
path.

 After the teeth are set in correct alignment the incisal pin is
returned to correct vertical dimension of occlusion.
 Prussian blue dye is painted on to the surface of generated
pathway. Opening and closing tapping movements are made
of stone path against the denture teeth.
 Spots of dye are transferred to the denture teeth. selective
grinding is done till the incisal tip touches the incisal table.

ADVANTAGES
1. The method does not require registration of inter occlusal
records or a face bow transfer and dispenses with the need for
a complicated articulator.
2. Jaw movements and tooth pathways are reproduced under
more nearly functional conditions.

LIMITATIONS
 Not indicated when the opposing occlusion is provided by a
complete denture or when all the teeth is not present in the
opposing occlusion.
 Resistance may be encountered by the mandible as the teeth
shear through the wax, which may serve to deflect the
mandible from its natural path.

 The patient’s masticatory force and direction may vary with
foods of different types. So the masticatory pattern of the
teeth during actual function differs from that which they
follow as they generate pathways.
 Cannot be used to replace the anterior teeth.

ESTABLISHING JAW RELATIONS FOR A
MANDIBULAR PARTIAL DENTURE OPPOSING A
MAXILLARY COMPLETE DENTURE

The maxillary denture may be already present or it may be
made along with the opposing partial denture.

 If the existing maxillary denture is satisfactory and has
acceptable occlusal plane, it can be treated as natural
dentition.

If the relationship of maxillary posterior teeth to the
mandibular ridge is favorable and the complete denture is
stable functionally generated method can be used to obtain the
records.

 If the maxillary denture has made with occlusal plane too low
and improper interarch relationship due to any malposition of
the natural teeth and if those teeth has been lost ,repositioning
of the maxillary posterior teeth should be done before the
construction of the partial denture.

If the mandibular partial denture will be tooth supported it
should be restored first and so the maxillary complete
denture is made later to occlude with an intact arch.

 If the mandibular partial denture has one or more distal
extension bases, the occlusion on both the arches should be
accomplished simultaneously.
 All mouth preparations and restorative procedures needed
should be accomplished on remaining natural teeth.

FIXED PARTIAL DENTURE AGAINST REMOVABLE
PARTIAL DENTURE
In this situation fixed partial denture should be fabricated
and then the construction of removable partial denture should
be made.
Better occlusion is possible if the occlusal plane is restored
with the abutment restorations and the teeth of removable
partial denture are then arranged to articulate with them.

Materials used for occlusal surfaces of artificial posterior teeth
1. Improved acrylic resin teeth opposed by natural teeth
2. Porcelain teeth opposed by porcelain teeth
3. Gold occlusal surfaces opposing natural teeth
4. Gold occlusal surfaces opposing fixed partial dentures

CONCLUSION
The knowledge, judgement, and skill of each dentist is
more important in treating patients than the technique or
concept to which he subscribes.

REFERENCES
1. Removable partial denture-McCracken’s.
2. Clinical removable partial prosthodontics-Stewart
3. Removable denture prosthodontics - grant
4. Removable partial prosthodontics-Grosso & Miller.
5. Partial dentures -Swenson

6. Occlusion in removable partial prosthodontics - Journal of
prosthet dent 2004; 91; 1-5.
7. Accurate occlusal relationship in partial denture
construction. Journal of prosthet dent 1998; 54; 526.
8. Clinical evaluation of the accuracy of interocclusal recording
materials- Journal of prosthet dent 1994; 52; 112.

Thank you
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Jaw relatios in rpd / orthodontic straight wire technique

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