jaw relation-prosthesis

Faculty of DentistryAssuit university 3rd year student

Feb, 21, 2016

Jaw relations

Recording Maxillo-Mandibular

Relations

Steps for making full denture

Primary impression

Primary cast

Secondary impression

Master cast

Trial denture baseOcclusion rims

Procedures of Recording Maxillo-Mandibular Relations

1) Checking extension, retention, and stability of occlusion rim

2) Establishing proper facial contour 3) Orientation of the occlusal plane 4) Determination of vertical dimensions5) Mounting maxillary cast according to face-bow 6) Registration of centric occluding relations 7) Registration of eccentric jaw relations

Checking extension, retention, and stability

Minimize the liability of recording wrong relationshipDue to : * ill fitting bases * Warpage of shellac trial bases

Checking extension, retention, and stability

Extend to functional depth Rounded and smoothFill the vestibule Post dam areaLingual extension Hamular notches area

Checking extension, retention, and stability

Maxilla Upward and forward ……….... Post-dam Downward…… border seal anteriorly Buccal…….. Border seal posteriorly

Mandible Downward and forward ……….... Posterior portion Upward …… border seal anteriorly Buccal…….. Border seal posteriorly

Checking extension, retention, and stability

Alternate vertical pressure on premolar region

The base shouldn’t teeter

Procedures of Recording Maxillo-Mandibular Relations

1) Checking extension, retention, and stability of occlusion rim

2) Establishing proper facial contour 3) Orientation of the occlusal plane 4) Determination of vertical dimensions5) Mounting maxillary cast according to face-bow 6) Registration of centric occluding relations 7) Registration of eccentric jaw relations

Establishing proper facial contour

Procedures of Recording Maxillo-Mandibular Relations

1) Checking extension, retention, and stability of occlusion rim

2) Establishing proper facial contour 3) Orientation of the occlusal plane 4) Determination of vertical dimensions5) Mounting maxillary cast according to face-bow 6) Registration of centric occluding relations 7) Registration of eccentric jaw relations

Orientation of occlusal plane

Orientation of occlusal plane Anterior occlusal plane influenced by: * Esthetics * Phonetics Posterior occlusal plane influenced by: * Anatomical land marks * Condition of residual ridge

Orientation of occlusal plane Anterior occlusal plane influenced by:

* Esthetics

* Phonetics

Orientation of occlusal plane Posterior occlusal plane influenced by:

* Anatomical land marks

* Condition of residual ridge

Procedures of Recording Maxillo-Mandibular Relations

1) Checking extension, retention, and stability of occlusion rim

2) Establishing proper facial contour 3) Orientation of the occlusal plane 4) Determination of vertical dimensions5) Mounting maxillary cast according to face-bow 6) Registration of centric occluding relations 7) Registration of eccentric jaw relations

Determination of vertical dimensions

Two measurable lengths of the face are important guides in making maxillo -mandibular relation records and are referred to as :

Vertical dimension of rest (VDR).

Vertical dimension of occlusion (VDO).

Determination of vertical dimensionsVertical dimension of physiologic rest position (VDR)

Vertical separation of the jaws when the opening and closing muscles of mandible are in a state of minimal tonic contraction sufficient only to maintain posture

Determination of vertical dimensions

Physiologic rest position The position assumed by the mandible when the head is in an upright position, the muscles are in equilibrium in tonic contraction and the condyles are in a neutral unstrained position is the physiologic rest position of the mandible.

Determination of vertical dimensions

Vertical dimension of occlusion (VDO)Vertical separation of the jaws when the teeth or occlusion rims are in contact.

Determination of vertical dimensions

Interocclusal Distance (IOD) Vertical separation of the jaws when the opening and closing muscles of mandible are in a state of minimal tonic contraction sufficient only to maintain posture.

Determination of vertical dimensions

VDR = VDO + IOD

VDR – IOD = VDO

Determination of vertical dimensionsMETHODS OF DETERMINING )VDR(1. FACIAL MEASUREMENT AFTER SWALLOWING

AND RELAXING.2. SPEECH3. TACTILE SENSE4. MEASUREMENT OF ANATOMICAL LANDMARKS5. FACIAL EXPRESSION.

Determination of vertical dimensionsMETHODS OF DETERMINING )VDR(FACIAL MEASUREMENT AFTER SWALLOWING AND RELAXING.

Determination of vertical dimensionsMETHODS OF DETERMINING )VDR(SPEECH• 1st method : Ask the patient to repeatedly

pronounce the letter ‘M’, a certain number of times. Distance is measured immediately after the patient stops.

• 2nd method: keep talking to the patient and measure the distance immediately after the patient stops talking.

Determination of vertical dimensionsMETHODS OF DETERMINING )VDR(TACTILE SENSE• Instruct the patient to stand erect and open the jaws

wide until strain is felt in the muscles. • When the opening becomes uncomfortable, ask him to

close slowly until the jaws reach a comfortable relaxed position.

• Measure the distance and compare it.

Determination of vertical dimensionsMETHODS OF DETERMINING )VDR(MEASUREMENT OF ANATOMICAL LANDMARKS• Distance between the pupil of the eye and Rima oris and the

distance between anterior nasal spine and lower border of mandible is measured using Willis guide.

• If both the distances are equal, jaws are considered at rest.

Determination of vertical dimensionsMETHODS OF DETERMINING )VDR(• FACIAL EXPRESSION. • Patients jaw will be in rest position when he is relaxed.• Skin around the eyes and chin should be relaxed.• Nostrils are relaxed and breathing is unobstructed.• Upper and lower lips have slight contact in one plane.

Determination of vertical dimensionsMETHODS OF DETERMINING )VDO(1. Pre-extraction records.2. Phonetic : ( closest- speaking space)

Determination of vertical dimensionsMETHODS OF DETERMINING )VDO(Pre-extraction recordProfile photograph : profile photograph are made and enlarged to life size . measurement of anatomic landmarks on the photograph is compared with measurement of the same anatomic landmarks on the face .

Determination of vertical dimensionsMETHODS OF DETERMINING )VDO(Pre-extraction recordProfile silhouettes :- The word silhouettes means " outline " ـــ An accurate reproduction of the profile in silhouette can be cut out in card board or contoured in wire

Determination of vertical dimensionsMETHODS OF DETERMINING )VDO(Pre-extraction recordRadiograph : profile radiograph of positions of condyles in the fossae with the teeth in occlusion  

Determination of vertical dimensionsMETHODS OF DETERMINING )VDO(Pre-extraction recordArticulated cast : A simple method of recording the vertical relation , as well as size and shape of the teeth , is through the use of diagnostic cast mounted on an articulator

Determination of vertical dimensionsMETHODS OF DETERMINING )VDO(Phonetic : ( closest- speaking space)The vertical dimension can be established by using ” closest-

speaking space “ This technique measures the space when the mandible is

involved in physiologic function of speech The patient says words beginning with the “ F or V “ to

determine position of maxillary anterior teeth , while position of the mandibular anterior teeth is determined by position of the mandible when patient says words beginning with the letter “ S “

Procedures of Recording Maxillo-Mandibular Relations

1) Checking extension, retention, and stability of occlusion rim

2) Establishing proper facial contour 3) Orientation of the occlusal plane 4) Determination of vertical dimensions5) Mounting maxillary cast according to face-bow 6) Registration of centric occluding relations 7) Registration of eccentric jaw relations

Mounting the maxillary cast according to face-bow record :-

Face-bow is a dental instrument that is used in the prosthodontics . it transfers the relationship of maxillary arch and temporomandibular joint to the casts. It aids in mounting maxillary cast on the articulator.

Mounting the maxillary cast according to face-bow record :-

-The condylar rods of the bow are positioned on a marked point 13 mm in front of the canthus – tragus line -The tip of infra-orbital pointer is positioned on the lowest part of infra-orbital margin . -The face bow fork is attached to maxillary occlusion rim . it is heated and pushed into the labial surface of the maxillary occlusion rim , 3mm above its lower border . -Wings of the fork must be parallel to occlusal plane , and midline coincide with the midline drawn on the maxillary occlusion rim - Condylar rods released , and the upper cast is mounted on the articulator

Procedures of Recording Maxillo-Mandibular Relations

1) Checking extension, retention, and stability of occlusion rim

2) Establishing proper facial contour 3) Orientation of the occlusal plane 4) Determination of vertical dimensions5) Mounting maxillary cast according to face-bow 6) Recording of centric occluding relations 7) Recording of eccentric jaw relations

Recording the centric relation-Centric relation: It is the most retruded physiologic relation of the mandible to maxilla , to and from which the individual can make lateral movements

Centric occlusion: It is the relation between the opposing teeth when the mandible is in centric relationCR is recorded after determination of VDO

Recording the centric relationSignificance: - it is adefinite position- can be repeated and the only relation which can be dublicated

- - occlusion is more stable if the teeth occlude with the jaws are in CR

Recording the centric relation

Methods of CR recording:- 1- Static Method( check bites )- 2- Functional Methods :- A) Graphic tracing method- B) Terminal hinge axis recording- C) chew in functional generating records

Recording the centric relationMethods of CR recording:- Static Method( check bites )- mandible should be in the most retruded position- use recording medium as :- 1- softened wax- 2-plaster of Paris 3- Zinc oxide eugenol paste

Recording the centric relation

Technique for interocclusal record using softened wax

( Check bite or wax wafet method )

A) Guide the mandible in centric relation

Patient in upright position

A) Guide the mandible in centric relation-insert occlusion blocks inside the mouth and guide the patient to occlude in centric relation by various methods :1- instructing patient to " let your jaw relax , pull it back and close slowly on your back teeth "2- instructing the patient to " get the felling of pushing your upper jaw out and close your back teeth together "3- instructing the patient to turn the tongue backward toward the posterior border of the upper trial denture base 4- instructing the patient to tap the occlusion rims or back teeth together repeteadly

B ) Mark Guidelines :- Midline - Canine lines

C) Locking the maxillary and Mandibular Occlusion blocks :

1- Two v-shaped grooves in occlusal surface of maxillary occlusion rimin premolar region / not parallel to each other

2 - remove 2 mm. of wax from lower occlusion block and replace them by softened wax

3- insert record bases and guide the patient to close in centric relation until light contact between the anterior sections of occlusion rims are made and VDO is restablished

4- remove occlusion blocks as one unit , chill in water5- remove excess wax

D) verification of centric relation record :

Occlusion blocks are re-inserted and mandible guided to centric position The mandibular wax projections shoud fit with the v-shaped

grooves and marked lines should coincide

Advantages : 1- decrease liability to displace soft tissue 2- equalization of pressure 3- simple method , no mechanical devicesDisadvantages: 1- difficulties in handling softened wax during record or possible distortion of the record after it was made 2- must be checked several time