AISWARYA K SAJEEVAN

FINAL YEAR BDS

Definition : The distance between two selected anatomic or marked points (usually on the tip of the nose and the other upon the chin), one on a fixed and one on a movable member (GPT-8).

It is recorded after doing the facebow transfer.

Physiologic rest position / rest vertical dimension (RVD)

Occlusal vertical dimension (OVD) Inter occlusal space / free way space

Physiologic rest position / rest vertical dimension (RVD)

Occlusal vertical dimension (OVD) Inter occlusal space / free way space

RVD – rest vertical dimensionOVD – occlusal vertical dimensionFWS – free way space

During the construction of complete dentures, the rest vertical dimension is determined first and then reduced or closed to the occlusal vertical dimension.

Some prosthodontists believe that the physiologic rest position tends to remain constant for variable periods of time.

Average inter occlusal distance = 2 to 4 mm

General considerations: The position of the mandible influenced by gravity. When a patient is tensed, under strain nervous,

tired, or irritable the values vary. In patients who suffer neuromuscular disturbances. The duration of maintaining the rest position is

usually short. No one method can be accepted for all patients. If no space is present between teeth in dentures,

discomfort, pain, generalized hyperemia and bone resorption occurs.

Facial measurements Tactile sense Phonetics Facial expression Anatomic land marks

Patient is instructed to stand or sit comfortably with head upright and eyes looking straight. A reference point is marked on the tip of

patient’s nose and chin. The patient is asked to wipe his lips with his

tongue, to swallow, and to drop his shoulders. When the mandible drops to rest position,

measure the points of reference.

Two markings are made, one on upper lip below the nasal septum, and the other on the chin.

The patient is told to swallow and relax. The distance between the marks is measured. The occlusal rims are adjusted until the distance

between the marks is 2 to 4mm less during occlusion.

Patient is asked to open his jaws wide for a period of time till patient feels uncomfortable.

Ask him to close slowly until the jaws reach a comfortable, relaxed position.

Measure the distance between the points of reference.

Speech is used in several different ways as an aid in establishing rest position. Two of these are,

Have the patient repeat the name Emma. When the lips contact , the jaw movement is stopped and the distance between the reference points is measured.

Engage the patient in a conversation that will divert patient’s attention. A pause in speech, followed by relaxation as indicated by a drop of the mandible, is indication for measurement.

By recognizing the relaxed facial expression when a patients jaw are at rest.

Lips will be even anteroposteriorly and at rest. The skin around the eyes and over the chin will

be relaxed. These are indications for recording the rest

position.

The Willis guide is designed to measure the distance from the pupils of the eye to the rima oris and the distance from the anterior nasal spine to the lower border of the mandible.

When these measurements are equal, the jaws are considered at rest.

Asymmetry of faces makes the value of average measurements using anatomic landmarks questionable.

The measurement of occlusal vertical dimension even in dentulous patients may not be accurate because in the course of a person’s lifetime many things happen to the natural teeth.

Thus the pre extraction may not reliably indicate the dimension to be incorporated in complete dentures.

Modification from pre-extraction values or previous dentures should be made as indicated when the information is available.

POST EXTRACTIONPREEXTRACTION

MECHANICAL PHYSIOLOGICAL

1. Ridge relations Distance from incisive papilla Parallelism of the ridges.2. Measurement of former dentures3. Preextraction records Profile radiographs Profile photographs Casts of teeth in occlusion Resin facemasks Facial measurements

Incisive papilla is a stable landmark that changes comparatively little with resorption of the alveolar ridge.

Distance of papilla from incisal edge of mandibular teeth approximately = 4mm

Distance of papilla from incisal edge of maxillary teeth approximately = 6mm

Mean vertical overlap = 2mm Drawbacks : Considerable individual variation Not relevant in patients with severe resorption.

The clinical crowns of anterior and posterior teeth have nearly the same length, their removal tends to leave the residual alveolar ridges nearly parallel to each other.

Paralleling of the ridges, plus a 5 degree opening in the posterior region as suggested by sears, often gives a clue to the correct amount of jaw separation.

Drawbacks :o Not reliable in case of marked resorption.o In most patients the teeth are lost at irregular intervals

and the residual ridges are no longer parallel.o Edentulous ridges of the mandible and maxillae become

progressively more discrepant from the standpoint of width. (mandibular ridge become progressively wider , and the maxillary ridge narrower, as bone resorption continues).

Measurements are made between the borders of the maxillary and mandibular dentures by means of a boley gauge.

If the observations of the patient’s face indicate that this distance is too short or too long, a corresponding alterations can be made in the new denture.`

Profile radiographs of face have been much used in research of vertical dimension.

Profile radiographs are made with teeth in occlusion and compared with those made with occlusal rims in position

Disadvantages Cannot be considered adequate for routine

clinical use in prosthodontic treatment because of radiation risks.

Profile photographs are made with teeth in occlusion and enlarged to life size. Measurements of anatomic landmarks on the

photograph are compared with measurements of the face, using the same landmarks.

Disadvantage Profile angles can change with changes in the

patient’s posture.

Simple method of recording vertical overlap relation and the size and shape of the teeth.

Gives an indication of the amount of space required between the ridges for teeth of this size.

Not commonly used nowadays. Lead wires are adapted to the patient’s profile

before extraction. The outline is transferred to a cardboard and cut out. After extraction the cut out is placed against patient’s profile to check vertical relation.

Acrylic face mask is made before extraction using a facial impression and cast.

This method is not practical.

The patient is instructed to close his jaws into maximum occlusion after two tattoo points are placed on upper half & lower half of face.

The distance is measured and compared with measurements made between these points when the artificial teeth are tried in.

1.Phonetics (Silverman’s closest speaking space)2.Facial expression & esthetics as guide3. Swallowing threshold4.Tactile sense Lytle’s neuromuscular perception technique Power point technique of Boos Patient’s tactile sense5.Electromyography

Measures vertical dimension when the mandible and the muscles involved are in physiologic function of speech.

Should not be confused with the free way space of the physiologic method by Niswonger and Thomson.

The free way space establishes vertical dimension when the muscles involved are at complete rest.

Incisive guidance is established by arranging the anterior teeth before recording vertical dimension. (Technique by Pound and Murrel)

The position of artificial teeth is determined by the position of the maxillae when the patient says words beginning with “f” or “v”

The mandibular anterior teeth by the position of the mandible when the patient says words beginning with “s”

1. Stable record bases are made.2. Contour the maxillary occlusal rim with stable

baseplate wax. The labiopalatal and buccopalatal width are kept the same as anterior and posterior teeth.

3. In mandibular record base, apply baseplate wax to a height of 2 or 3 mm over the superior surface. A section of beeswax about ¾’’ high is placed in the estimated location of four anterior teeth. This section of beeswax is referred to as speaking wax.

4. Place the maxillary occlusal rim in patient’s mouth. Adjust the rim to provide lip support. When the “f” and “v’ sounds are pronounced the incisal edges of the maxillary anterior teeth create a seal on the moist area of the vermillion border of the lower lip.

5. Have the patient repeat the word “first” or “Victor” and contour the wax to create the seal.

6. Record the midline on the wax rim and arrange the two artificial central incisors, one on each side of the midline, with the incisal edges perpendicular to the long axis of the face.

7. Remove the record base from mouth and arrange the lateral incisors and canines.

8. Seat the mandibular record base with the attached “speaking wax”. Have the patient repeat the numbers 6 & 65 and adjust to the “s” position. ie; When the “s” sounds are pronounced the mandible moves forward. The incisal edges of the anterior teeth do not make contact.

9. Record the centre line on the wax rim to coincide with the midline of the maxillary incisors.

10. After removing the mandibular record base from patient’s mouth, remove the speaking wax from one side of the center line. Replace the wax with central and lateral incisors, with the neck of the teeth inclined towards the crest of the residual ridge. Remove the remaining wax and arrange the other central and lateral incisors.

11. Adjust the wax rim to parallel the Camper’s line. Notches placed in hard maxillary rim to aid in repositioning the vertical dimension & central occlusal records.

12. Place soft recording wax on the posterior superior surface of the mandibular base to a height that exceeds the anticipated occlusal vertical dimension. Seal it to the hard wax.

13. Place the maxillary record base and assure that it is stable and retained.

14. Seat the mandibular record base and ask the patient to retrude the mandible from the “s” position to a comfortable retruded relation and then to close until a firm posterior contact is encountered.

15. Remove the record base and check for alignment and sufficiency.

16. Repeat step 4 until the incisal edges of the mandibular teeth contact firmly against the maxillary teeth or the palate ( in class II).

Casts are mounted. Mount central bearing plates directly on the

accurately adapted record bases, adapting the plates to the patient’s inter arch distance

Adjust the bearing pin until the mouth is opened beyond the physiologic rest position. When the patient signifies he has reached excessive opening turn the pin back a half turn.

These steps are repeated for obtaining consistent values.

Soft fast setting plaster is injected to secure the relation.

Attach bimeter to accurately adapted mandibular record base.

A metal plate is attached to the vault of maxillary denture base to provide central bearing point.

The gauge indicates the pounds of pressure generated during closure at different degrees of jaw separation.

When the maximum power point is determined lock the set nut, make plaster registrations and transfer record to articulator.

The theory behind the method is that when a person swallows, the teeth come together with very light contact at the beginning of the swallowing cycle.

The technique involves building a cone of soft wax on the lower denture base so that it contacts the upper occlusion rim with the jaws too wide open.

The flow of saliva is stimulated and the repeated action of swallowing will gradually reduce the height of wax cone to allow the mandible to reach the level of occlusal vertical relation.

It is difficult to find consistency in the final vertical positioning of the mandible by this method.

1)    Discomfort to the patient

2)    Trauma: by the jamming effect of the teeth coming into contact sooner than expected may cause not only discomfort but also pain owing to the brusing of the mucous membrane by these sudden and frequent blows.

3)    Loss of freeway space: which may be lead to

Muscular fatigue of any one or group of muscles of mastication

Trauma caused by the constant pressure on the mucous membrane and

Annoyance from the inability to find a comfortable resting position.

4)  Clicking teeth: the tongue which has become accustomed to the presence of teeth in certain fixed positions and during speech helps to produce sounds without the teeth coming into contact. When there is increase in vertical height opposing cusps frequently meet each other, producing an embracing clicking or clattering sound. This effect is also produced during eating.

5)     Appearance: the face has an elongated appearance since at rest the lips are parted and closing them together will produce an expression of strain

6)   Bone residual alveolar ridge undergoes rapid resorption

1) Inefficiency – which is due to the fact that the

pressure with which it is possible to exert with the

teeth in contact decreases.

2) Cheek biting: In some cases where there is a loss

of muscular tone, as well as reduced vertical height,

the flabby cheek tends to become trapped between

the teeth and bitten during mastication.

3) Appearance: the general effect of over closure on facial expression is of increased age. There is close approximation of nose to chin, the soft tissues sag and fall in and the lines on the face are deepened. The lips loose their fullness and the vermilion borders are reduced to approximate a line.

4) Angular cheilitis: Reduced vertical relation results in a crease at the corners of the mouth beyond the vermilion border and the deep fold thus formed becomes bathed in saliva, thus leading to infection and soreness.

5) Pain in the TMJ’s: Trauma in the region of the temporomandibular fossa may be attributed to a reduced vertical relation with symptoms like obscure pains, discomfort, clicking sounds, headaches and neuralgia.

Syllabus of complete dentures, Charles M. Heartwell, Jr, Arthur O.Rahn (4th edition)

Prosthodontic treatment for edentulous patients, Zarb-Bolender (12th edition)

Essentials of complete denture prosthodontics, Sheldon Winkler (2nd edition)