6 a Seminar on Vertical Jaw Relation

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A seminar on vertical jaw

relationBy Dr. Amit N. Sadhwani,

PG Dept. of Prosthodontics, Crown and Bridge

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The face is more honest than the mouth will ever

be.

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We constantly strive in restoring the honesty of

the face

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Vertical relation of the upper and lower jaws indirectly reflect the changes on the face of a patient.

For the edentulous, it is we who have to try and restore it to as normal as

possible.

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Contents• Introduction • Clinical significance of

jaw relations in general• Definitions • Classification • History • Constancy of facial

height concept • Methods of recording

vertical jaw relation

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Facial index as described by Martin and Sellar

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Contents (contd.)Mechanical methods :

• Ridge relation • Measurement of former

dentures• Pre-extraction guides :

Profile radiographs Profile photographs Profile tracing (lead wire

adaptation) Profile silhouettes Articulated models Dakometer Willis gauge Facial measurement (Tattoo

Point) Swenson’s method

Use of anterior teeth measurements

Direct procedure for indicating mandibular rest

position.

• Post Extraction methods: Niswonger’s Method Power Points Concept of equal thirds Willis’ measurements Electromyography Neuromuscular perception

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Contents (contd.)

Physiologic methods :

Physiologic rest position Phonetics Facial expression Swallowing threshold Tactile sense

• Effects of increased vertical dimension• Effects of decreased vertical dimension• Conclusion • References

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Clinical significance of Jaw relations in edentulous

• To re-establish the functional position of the mandible

• Comfort • Esthetics • Phonetics • Functional efficiency • Structural balance

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Introduction

• VD- Amount of separation of the jaws.

• Essential in the successful practice of many phases of dentistry.

• Greatest cause of complete denture difficulties- failure to restore the lost vertical dimension to normal.

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Definition

• Maxillomandibular relationship, GPT VIII

• Any spatial relationship of the maxillae to the mandible;

• Any one of the infinite relationships of the mandible to the maxillae

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Classification of Jaw relations

• Orientation jaw relation.

• Vertical jaw relation.

• Horizontal jaw relation.

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Definition

Vertical dimension, GPT VIIIThe distance between two selected anatomic or marked points (usually one on the tip of the nose and the

other upon the chin), one on a fixed and one on a movable member

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Principle

The single most important factor in deciding the vertical dimension in infants and in edentulous adults is

the mandibular musculature.

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Classification

• The vertical jaw relation can be classified as follows:

1. Vertical dimension at rest- VDR2. Vertical dimension of occlusion-

VDO

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Rest vertical dimension

The distance between two selected points

(one of which is on the middle of the face or nose and the other of which is on the lower

face or chin) measured when the mandible is in the physiologic rest

position.

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Physiologic rest positionGPT-VIII

• 1: The mandibular position assumed when the head is in an upright position and the involved muscles, particularly the elevator and depressor groups, are in equilibrium in tonic contraction, and the condyles are in a neutral, unstrained position

• 2: The position assumed by the mandible when the attached muscles are in a state of tonic equilibrium. The position is usually noted when the head is held upright

• 3: The postural position of the mandible when an individual is resting comfortably in an upright position and the associated muscles are in a state of minimal contractual activity

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Vertical dimension of occlusion, GPT VIII

Occlusal vertical dimensionThe distance measured between two points when the occluding members

are in contact.

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The repetitive contracted length of the elevator muscles determines the vertical dimension of occlusion.

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Inter-relationship

VDR-VDO=Freeway space or the

interocclusal rest space

Interocclusal rest space: GPT VIII

The difference between the vertical

dimension of rest and the vertical

dimension while in occlusion.

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Postural rest position is influenced by the position of the lower jaw.

A “range of posture” rather than a single rest position is usually noted.

Postural rest position is further influenced by the position of the head.

Upright, unsupported head, while records are made, is the key.

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Significance of Physiological Rest position

• Bone to bone relation• Fairly constant

throughout the life in absence of any pathosis.

• Acceptable limits while recording is made is permitted.

• Used to determine the VDO.

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Dawson’s four pointer to understanding vertical dimension

• You cannot determine vertical dimension based on whether the patient is comfortable.

• Measuring freeway space is not an accurate way to determine correct vertical dimension of occlusion(VDO)

• Determining the rest position of the mandible is not a key to determining vertical dimension.

• Lost vertical dimension is not a cause of TMD.

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History and references

1771 is when Hunter described the range of motion of muscles and ligaments surrounding

the joints of the body.

Wallisch in 1906 was the first to define physiologic rest position.

Thomson and Brodie in 1942 stated that position of the mandible in relation to face and head

and proportions of any face as far as vertical is concerned is constant throughout the life.

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Constancy concept of face height

• Niswonger in 1934.• Neutral position- Equilibrium of the opening

and closing muscles.• “Jaw relator”- A gauge to measure the vertical

dimension of the face.• 200 dentulous patients were studied, and a

conclusion was made that teeth slowly wear down, nature makes the necessary changes in the bone and soft tissues to maintain a particular interocclusal clearance.

• He correlated these findings in the edentulous individuals to find the effects with change in vertical and denture success.

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Role of muscle physiology

• Mershon(1938) contended that muscle cannot lengthen to accommodate an increase in bone size, but rather bone adapts itself to the length of the muscles.

• Schlosser in 1941 came up with the importance of phonetics in determining vertical relation. Identical rest position was achieved y sounding the letter ‘M’.

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Varied school of thought

• Harris and Hight (1936) reasoned that VDO was dependent on the occlusal contacts in the closing movements of the mandible. Hence abrasion of teeth, resorption of ridges under dentures make the correct vertical opening in edentulous debatable.

• Olsen, Atwood and Tallgreen used longitudinal radiographic analysis and cephalometrics to show instability in the rest position after removal of teeth.

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Swerdlow-1964• Cephalometric study in immediate

denture patients over a period of 6 months.

• The transition period of dentition showed

I. Phonetic method was more reliable than the swallowing method.

II. VDR and VDO increased initially and then decreased markedly in 6 months.

III. The interocclusal distance is self adjusting.

IV. Mandibular load influenced the rest position.

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Methods of determining vertical jaw relation

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Factors considered for rest position

• The position of the mandible is influenced by gravity; so the patient should be seated upright or standing with the head erect, looks straight ahead when jaw relation records are made.

• Patient should be calm, cool and relaxed when the jaw relations are recorded.

• Neuromuscular disturbances make the records difficult. With these patients the operator must be very considerate and cool.

Syllabus of complete dentures : Charles M. Heartwell Jr., Arthur O Rahn, 4 th Edition

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Factors(contd.)

• The dentist should be prepared to make measurements without delay when the position is assumed because the rest position is not to be maintained for a duration of time.

• No one method for determining rest position can be accepted as being valid for all patients. Several methods are available to confirm this record.

Syllabus of complete dentures : Charles M. Heartwell Jr., Arthur O Rahn, 4th Edition.

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Classification of the methods

• Mechanical• Physiological• Esthetics as a guide combines the

use of both the methods listed above.

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Ridge relations• Parallelism of ridges:

Paralleling and a 5 degree opening in the

posteriors as acceptable was suggested by

Sears. Marked resorption of the ridges

makes this rule void.• Distance of incisive papilla from mandibular

incisors: A stable landmark, little change on resorption. Gives an average measure of the

vertical overlap.

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Measurement of former dentures

Measurements are made from the

intaglio surfaces of the dentures on the

corresponding crestal areas of the ridge.

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Pre-extraction guides

One can usually establish an occlusal position, record it and transfer it to the

edentulous situation.

There are several ways of accomplishing it.

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Profile radiographs

Lateral skull radiographs before and after extractions with

trial bases.

Comparisons help to bring the necessary

changes in the position of the mandible

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Profile photographs

• Made with teeth in maximum occlusion.

• Measure of the anatomical landmarks on the

photographs are compared. • When the records are made

and when the try in is done.

• Disadvantages : Angulation of the photos

might differ.Photo enlargements cause

inaccuracies.

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Profile tracing and Silhouettes

Lead wire adaptation along the midline helps preparing a cardboard cutout, which is preserved after extraction.

Vertical estimation is done by matching

the new profile with the cutout.

Flashlight profile tracing by artists

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Articulated casts and models

• Articulation of casts to correct anatomic

positions with a facebow transfer before and after extractions help in the

inter arch measurements.

• Long period of fabrication and

excessive bone loss during extractions might

limit its use.

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Dakometer

• Bennett's Dakometer made by Elliot brothers in London during 1929-

35.• Records both the vertical

dimension with natural teeth and the position of

the central incisors.• Consists of the nose and

chin piece which are secured with compound to measure the readings on the spring gauge (on

the right).

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Willis’ measurement and gauge

Disadvantage being inaccuracy, as the degree of pressure applied may not be same every time.

The distance from the lower border of the septum of the nose to lower border of the chin is equal to distance from the outer canthus of the eye to the corner of the mouth in the rest position.

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The Venus and the Apollo gauge

Courtesy: Mr. Curette Tech, S. Korea

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Facial measurements through tattoo points

This could possibly be the most phased out technique for obvious

reasons of permanent tattoos.

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Acrylic face masks

• Acrylic face masks are made before extractions

and verified when the patient is rendered

edentulous.• Time consuming, requires a lot of skill and

experience.• Different topography of

face in erect and recumbent posture.

Swenson’s Complete Dentures, Boucher, Editor, Fifth edition

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Use of anterior teeth in determining OVD

• A polyether impression of the muco-labial reflection of the upper and lower lip and labial surfaces of left to right canine is made.

• The distance from the height of muco-labial reflection of the upper lip to the tip of the anteriors are reproduced in the artificial dentition.

Fayz F, Eslami A, Craser G ; “Use of anterior teeth measurement in determining occlusal vertical dimension”, J Prosthet Dent, 1987,

58 (3) : 317 – 322

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Direct procedure for indicating mandibular rest position

• A L-shaped wire is attached to the skin on the mental protuberance, a vertical millimeter scale is fixed to a stationary head gear.

• A mean value of opening and closing exercises until the lips just touch each other act as a reference measurement.

• The height of the mandibular rim is adjusted accordingly.

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Post extraction measurements

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Niswonger’s method• The camper’s plane or the

ala-tragus line and the inter- pupilliary line are the hallmarks of this procedure.

• An upright position leads the planes to be parallel to the floor.

• The marks are made on the tip of the nose and the most stable area on the chin.

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• The distance between the marks is recorded after the patient is asked to swallow and relax.

• Subsequently occlusal rims are fabricated so that when they occlude, have a measurement 1/8” less than the original measurement.

• This 1/8” average gives a freeway space of 2 to 4 mm.

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Boos’ Bimeter or the PowerPoint device

• Boos in 1940 found that there is recordable point of maximum biting power. The device used is known as bimeter which is a type of spring gnathodynamometer.

• Bimeter is attached to a mandibular record base and a metal plate to the vault of maxillary base for the central bearing point.

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

• Maximum point is locked, plaster registration made and transferred to the articulator.

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Boucher LJ, Zwemer TJ and Pflughoeft F, Can biting force be used as a criterion for registering vertical dimension?, J Prosthet Dent, Volume 9,

4, Jul–Aug 1959, Pages 594–599

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Lytle’s Neuromuscular perception

• Lytle RB in 1964• A central bearing device is attached to accurately adapted

record base. It relies on patient’s perception of different vertical height.

• Bearing pin is adjusted beyond the rest position, pin is then lowered by half turn. Patient has to signify over-closure.

• Pin is raised again till excess opening is seen.• Appropriate vertical relation is judged by the patient.• Disadvantage being that it cannot be used in patients with poor neuromuscular coordination.

Lytle RB, Vertical relation of occlusion by the patient's neuromuscular perception, Volume 14, Issue 1, January–February 1964, Pages 12–21

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Electromyography

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Non specific EMG activity

From Michelloti A, Faralle M, Vollaro S et al.: Mandibular rest position and electrical activity of the masticatory muscles, J Prosthet Dent 78: 48-53,

1997.

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Electromyography • Neuromuscular dentistry has

found an important position in Prosthodontics.

• The rest position of the mandible can be determined by means EMG activity.

• Hence a stable reference point may be achieved for recording vertical dimension values.

• Disadvantages:

Expense with a complex apparatus is required.

Adequate knowledge

Mack MR, Vertical dimension: A dynamic concept based on facial form and oro-pharyngeal function;Vol 66, 4, Oct 1991, Pages 478–485

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Physiologic methods

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Rest position tests• This is one of the routine exercises in the

Jaw relation whereby an interocclusal rest space of 2-3 mm is noted in the premolar region between the occlusal rims.

• Again indelible dots or adhesive tapes on the reference points are used.

Too high a vertical seen if the inter-arch space is less than 2mm, and

Too low a vertical is seen if the inter-arch space is more than 4mm.

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Phonetics as a guide- Silvermann’s method

• Silvermann in 1952 proposed this method.

• He identified that production of certain sounds like “S, Z, Sh, Zh, J, Ch” as in buzz, fish and church brings the upper and lower anterior teeth very close to each other.

• Correct placement of lower incisors makes them directly under the upper member during this exercise.

• The position of tongue is evaluated by asking the patient to pronounce “Thirty three” for the tip of tongue to protrude between anterior teeth.

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Method• The method was originally evaluated in natural dentition by Silvermann.

• The reference lines were marked on the lower anterior tooth.

• With respect to the artificial dentition, keeping the labio-lingual thickness of the occlusal rims as that of the natural or denture teeth is important.

• Adjust the lip support.

• The closest speaking space is adjusted until a minimum of 2mm space is achieved when the patient pronounces “S”.

Silvermann MM, The speaking method in measuring vertical dimension, J Prosthet Dent, 3, 2, March 1953, Pages 193–199

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Facial expression• Vertical relation at rest can be judged by a

number of facial details.

• In normal related jaws, the lips will be even antero-posteriorly and in slight contact.

• Patient with a retruded mandible has uneven lip position and the two are not in contact. Vice versa is observed in case of prognathic mandibles.

• Skin around eyes and chin should be relaxed, relaxation around the nares reflects unobstructed breathing.

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Swallowing threshold• At the beginning on the swallowing

cycle the teeth come together with a very light contact.

• The technique involves building cones of soft wax on the lower denture base so that it contacts the upper occlusal rims with the jaws too wide open.

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

• Cine-fluorographic studies on swallowing patterns affecting the vertical dimension is shown by Sheppard and Sheppard.

Sheppard I, Sheppard S; The relationship of vertical dimension to atypical swallowing with complete dentures, JPD, Vol38, 3, Sept.

1977, Pages 249–253

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Tactile sense

• This method is almost identical to the neuromuscular perception method described earlier.

• A central bearing device may or may not be used for determining the correct vertical.

• The patients neuromuscular coordination is important, it might not be useful for senile patients or the ones with impaired neuromuscular coordination.

Boucher mentions it as “Patient perceived comfort”

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Centric tray –BPS, Ivoclar Vivadent

One of the latest techniques to record a trial vertical relation

makes use of a centric tray with an irreversible

hydrocolloid as the recording medium.

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The importance of Try In• The rims with trial record bases might

act as an important aid in determining the vertical but the importance of waxed up teeth cannot be underestimated.

• The try in of a complete denture should be a detailed appointment whereby the vertical relation is verified, esthetics of the face, facial support and phonetics are evaluated.

• Last but not the least the comfort of the patient with the new set up is analyzed.

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Effects of increased vertical dimension

• Discomfort to the patient.

• Trauma and pain under the basal seat areas of dentures: The jarring effect of the teeth coming into contact sooner than expected may not only cause discomfort but in most cases it will also cause pain owing to the bruising of the mucosa

• Loss of free way space : Muscular fatigue of any one or group of muscles of mastication. In turn results in annoyance from the inability to find comfortable resting position.

• Clicking sound : When occlusal vertical dimensions is increased, opposing cusp will frequently meet each other producing an embarrassing clicking sound.

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• Appearance : Elongated appearance and at rest the lips are parted; Patient tries to close them together producing an expression of strain.

• Bone resorption : Due to continuous pressure on the residual alveolar ridge it undergoes rapid resorption.

• Loss of retention and stability : Leverages are caused due to premature contacts, further loss of ridge leads to loss of retention and stability.

• Generalized Hyperemia : Space between the teeth is essential when mandible is at rest. If no space is present between the teeth in denture, it may result in generalized hyperemia.

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Mc Cord, Grant; Prosthetics: Registration Stage II: Intermaxillary relations, British Dental Journal 188,

601 - 606 (2000)

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Correcting excessive vertical dimension

A METHOD FOR CORRECTION OF INCREASED VERTICAL DIMENSION

IN COMPLETE DENTURES, Kharat DU.

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Effects of decreased vertical relation

Inefficiency : Pressure which is possible to exert with teeth in contact decreases considerably with over closure because the muscles of mastication acting from attachments have been brought closer together.

Cheek, Tongue and lip biting : Loss of muscular tone, as well as reduced vertical height, the flabby cheek tend to become trapped between the teeth during mastication.

Appearance (Denture look) : The general effect of over closure on facial appearance is of increased age because of closure approximation of nose to chin, soft tissue sag and fall in and the lines on the face are deepened.

Inadequate lip support results in a flat upper lip with loss of vermillion border, loss of muscular function and loss of dominance of upper lip over lower lip will give a denture look.

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Angular cheilitis (perleche) : A reduced vertical dimension 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.

Pain in temporomandibular joint : Over closure may cause pain in temporomandibular joint probably due to strain of the joint and associated ligaments.

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Costen’s syndrome (Mild catarrhal deafness):

There will be a tendency to push the tongue towards the throat, adjacent tissues will be displaced, which may in turn result in occlusion of Eustachian tubes which would interfere with function of ear which may cause ear discomfort and impaired hearing. • Tinnitus or snapping noises in joint. • Tenderness to palpation over T.M.J.• Dryness of the mouth.• Various neurologic symptoms such as burning or picking

sensation of the tongue.

Prognathism : Over the years as a result of resorption of ridges and abrasion of denture teeth, there is a loss of occlusal vertical dimension. So the lower jaw over-closes in a forward and upward direction. Then the patient may appear prognathic. Weinberg L, Role of condylar position in TMJ dysfunction-

pain syndrome, J Prosthet Dent, Vol 41, 6, Jun 1979, Pages 636–643

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Mc Cord, Grant; Prosthetics: Registration Stage II: Intermaxillary relations, British Dental Journal 188,

601 - 606 (2000)

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Conclusion

• Many methods of assessing and recording vertical jaw relations in edentulous patients have been presented and evaluated.

• Since there is no precise scientific method of determining the correct vertical relations, the registration of vertical relations depends upon the clinical experience and judgment of the dental surgeon himself.

• It is art rather than a science. This is the reason why there are several of methods in use and why one method is as good as other.

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References• Prosthodontic treatment for edentulous patients : Boucher

• Syllabus of complete dentures : Charles M. Heartwell Jr., Arthur O Rahn

• Complete denture prosthodontics : John .J Sharry

• Functional Occlusion, From TMJ to smile design: Peter E Dawson

• Irving M. Sheppard, Stephen M. Sheppard, “Vertical dimension measurements”, JPD 1975, 34(3) : 269 – 277

• A.J. Turell; “Clinical assessment of vertical dimension”, JPD 1972, 28(3) : 238 – 246

• Silvermann MM; “The speaking method in measuring vertical dimension”, JPD 1953, 3(2) : 193 – 199

• Swerdlow H; Vertical Dimension literature review, J Prosthet Dent March April 1965, Vol 15, no. 2. 241-247.

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References • Farhad Fayz, Ahmad Erlami, Gerald N. Grascr ; “Use of anterior teeth measurement

in determining occlusal vertical dimension”, JPD 1987, 58 (3) : 317 – 322

• Wein L.A. “Vertical dimension A research and clinical analysis”, JPD 1982, 47 (3) : 290 – 302

• Kleinman .A.M. Shephard J.M, “A direct procedure for indicating mandibular rest portion” JPD 1972 ; 28 : 19 – 20

• Wagnu A. G “Comparison of 4 methods to determine rest portion of the mandible”, JPD 1971, 25 : 506 – 514

• Lytle RB, “Vertical relation of occlusion by the patients neuromuscular perception”, JPD 1964, 14 : 12 – 21

• Mc Cord, Grant; Prosthetics: Registration Stage II: Intermaxillary relations, British Dental Journal 188, 601 - 606 (2000).

• Glossary of prosthodontic terms : VIII Edition

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