Silverman’s closest speaking space
• It is defined as ‘the closest relationship of the occlusal surfaces and incisal
edges of the mandibular teeth to the maxillary teeth during function and
• Meyer Silverman (1953) suggested the use of closest speaking
method to record vertical dimension.
• This method can be used as follows:
• To determine vertical dimension during jaw
• To verify the available interocclusal space during
Method to record closest speaking space
• The patient is seated in upright position with head unsupported and
made to close in centric occlusion.
• A line is drawn on the lower anterior teeth at the horizontal level of
the incisal edges of the opposing upper anterior teeth.
• This line is called centric occlusion line.
• The patient is asked to pronounce words such as Mississippi or to
count numbers 60 onwards (s sounds).
• During pronunciation of these words, the upper anterior teeth come
• This is the closest speaking relation of the mandible to the maxilla
• Again a horizontal line is drawn on the lower anterior teeth at the
horizontal level of corresponding upper teeth.
• This line is called closest speaking line.
• The distance between the centric occlusion line and the closest
speaking line is called the closest speaking space between the upper
• This space is usually 1–2 mm.
• A decrease in closest speaking space indicates increased vertical
• The closest speaking space measures vertical dimension when the
mandible and muscles involved are in physiologic function of
• It is considered as dynamic or functional position.
FIGURE 6-9 Silverman’s closest speaking space.
Effects of altered vertical dimension
Effects of excessively increased vertical
• Increased lower facial height
• Difficulty in swallowing and speech
• Trauma caused by constant pressure on mucosa
• Clicking of complete dentures
• Stretching of facial muscles produces expression of strain
• Excessive trauma to the lower denture-bearing area
FIGURE 6-10 Altered vertical dimension.
Effects of excessively decreased vertical
• Decreased lower facial height
• Angular cheilitis due to folding of corners of mouth
• Pain, clicking and discomfort of TMJ may result in TMJ pain
• Drooping of corners of the mouth
• Thinning of vermilion borders of the lip
• Obstruction of Eustachian tube due to elevation of the soft palate
due to elevation of tongue and mandible
• Increased trauma to denture-bearing area
‘The maxillomandibular relationship in which the condyles articulate with
the thinnest avascular portion of their respective discs with the complex in
the anterosuperior position against the slopes of articular eminences. This
position is independent of tooth contact. This position is clinically discernible
when the mandible is directed superiorly and anteriorly. It is restricted to a
purely rotary movement about the transverse horizontal axis’. (GPT 8th Ed)
‘The most retruded physiologic relation of the mandible to the maxillae to
and from which the individual can make lateral movements. It is a condition
that can exist at various degrees of jaw separation. It occurs around the
terminal hinge axis’. (GPT 5th Ed)
‘The most retruded relation of the mandible to the maxillae when the
condyles are in the most posterior unstrained position in the glenoid fossae
from which lateral movement can be made at any given degree of jaw
Generally, there are four accepted theories to explain the centric
This theory considers CR to be a product of a dense reflex which
causes the external pterygoid muscles to contract and thus to halt the
jaw every time the condyles or the interarticular disc approach the
posterosuperior depth of the glenoid fossae.
It does not explain the following:
• CR is same at any vertical level
• The sharpness of Gothic arch
This theory was advocated by A. Ferrein.
• Ligament joins the elements of articulation, limits their movements
and is capable of determining terminal border positions.
• It provides acceptable physiologic explanation.
• It does not explain the lateral border movements.
• It does not explain the satisfactory location of hinge axis.
• This theory was proved by M.L. Meyers.
• It involves a retrusive terminal stop formed by the soft tissues of the
posterior part of the roof of the glenoid fossa.
• This fibrous stop acts as a buffer and was found to be loose, fibrous
and functionally differentiated.
• Zenker called this structure as ‘retroarticular cushion’.
• This theory was given by P. Saizer.
• The CR position is myologically active position.
• In order to attain this position and maintain it, a patient should
retain the predominance of the retropulsive and elevating muscle
Significance of Centric Relation
• It is a bone–bone relationship.
• It is repeatable, recordable and learnable position which remains
• The patient can voluntarily and reflexly return to this position.
• CR is a horizontal reference position in recording
maxillomandibular relations and a starting point for developing
occlusion. It is a point of return.
• This position is verifiable.
• The CR and centric occlusion of the artificial dentures should
coincide, otherwise the stability of dentures will be jeopardized.
• The casts should be mounted in CR because it is a point from which
all movements can be simulated on the articulator.
• CR should be accurately recorded and transferred onto the
articulator to permit proper adjustments of the condylar guidance.
• Edentulous patients use CR position for chewing and swallowing.
• The muscles, bones, ligaments, teeth and all related structures grow
into this muscle centre. Stability of natural teeth is jeopardized when
mandible loses its centric position.
Methods of retruding mandible in centric relation
• The mandible should be in its most posterior position while
• Some patients may show difficulties in retruding the mandible due
to certain biological, psychological and mechanical difficulties.
Method of retruding the mandible
• Relax the patient. Make him/her feel comfortable.
• The patient is asked to try to bring his/her upper jaw forward while
occluding on the posterior teeth.
• The patient should be instructed to touch the posterior border of the
upper record base with his/her tongue.
• The mandible occlusal rim should be tapped gently with a finger.
This would automatically make the patient to retrude his/her
• The temporalis and the masseter are palpated to relax them.
Difficulties in retruding mandible
Difficulties in retruding the mandible can be classified as follows:
• Lack of coordination between groups of opposing muscles when the
patient is requested to close in the retruded position.
• Habitual eccentric jaw relation.
• Inability of the patient to follow the dentist’s instructions is one of
the major psycho-physiological factors, which produce difficulty in
• This is overcome by instituting stretch–relax exercises, training the
patient to open and close his/her mouth. Central bearing devices
can also be used to retrude the mandible in these patients.
Poorly fitting base plates produce difficulty in retruding the mandible.
The base plates should be checked using a mouth mirror for proper
Factors affecting centric relation records
Factors influencing the CR records are:
• Resiliency of the supporting tissues
• Accurate fit of the denture bases will ensure adequate retention and
• TMJ and its associated neuromuscular mechanism – any deviation
from the normal will affect the records
• Technique used in making the records and the accuracy of the
• Skill and the knowledge of the clinician
• Cooperation and physical and mental well-being of the patient
• Correct maxillomandibular relationship
• Size and form of the residual alveolar ridge
• Quality and quantity of the saliva
• Size and position of the tongue
• Psychic or emotional stress to the patient
• Protective relax action caused by the faulty occlusal contacts
• Materials and equipment used for making the records
• Accuracy of the articulators
• Use of articulators which do not adjust to all interocclusal check
Concepts of centric relation records
There are two basic differences in concepts and objectives of the CR
records as they relate to occlusion.
• The CR record should be made with minimal closing pressure so that
the tissues supporting the bases will not be displaced while the
• The objective behind this is to achieve a uniform contact of the teeth
touching simultaneously at the very first contact. The uniform
contact of the teeth will not stimulate the patient to clench and relax
the closing muscles in periods between the meals.
• The CR records should be made under heavy closing pressure, so
that the tissues under the recording bases are displaced while the
• The objective of this concept is to simulate the same displacement of
the soft tissues as it would exist when the heavy closing pressure is
applied on the dentures. Therefore, the occlusal forces would be
distributed over the supporting residual ridges when the heavy
closing pressure is applied to the dentures.
• If the distribution of the soft tissues is uneven, the teeth will contact
unevenly on their first contact.
• This uneven contact can stimulate the nervous patient to clench and
relax the closing muscles of the jaws which can result in changes in
Both the concepts can be used to make CR records, but the clinician
should decide which method is best for individual patients. For most
of the patients, the first technique will provide best results.
Methods of Recording Horizontal Jaw
Classification of methods for recording CR:
(i) Static methods: In this, the mandible is caused to assume CR
position and the rims are locked into this position. Advantage is that it
causes minimal displacement of the recording bases in relation to the
(ii) Functional methods: Records are made when the mandible is in
function. The disadvantage of this method is causing lateral
displacement and anteroposterior displacement of the recording
A. Gysi and R.H. Kingery Classification
Patient-guided methods of recording CR
• Gothic arch (arrow point tracing)
• Three finger chin point guidance methods
• Bimanual manipulation method
• Anterior guidance with Lucia jig
• Anterior guidance by a leaf gauge
• Anterior guidance by OSU Woelfel gauge
• Power centric registration method
Graphic method of recording centric relation
Gothic arch tracing is defined as ‘the pattern obtained on the horizontal
plate used with a central bearing tracing device’. (GPT 8th Ed)
Gothic arch tracer is defined as ‘the device that produces a tracing that
resembles an arrowhead or a gothic arch. The device is attached to the
opposing arches. The shape of the tracing depends on the relative location of
the marking point and the tracing table. The apex of a properly made tracing
is considered to indicate the most retruded, unstrained relation of the
mandible to the maxillae, i.e. centric relation’. (GPT 8th Ed)
Graphic method records the tracing of the mandibular movements in
one plane. Graphic method can be accomplished either intraorally or
extraorally depending on the placement of the recording device (Table
DIFFERENCES BETWEEN EXTRAORAL AND INTRAORAL
Extraoral Tracers Intraoral Tracers
Placed outside the oral cavity Placed in the oral cavity
Tracings are larger Tracings are smaller
Apex is more discernible Difficult to locate true apex
No hole is required Tracer should seat in the hole for accuracy
Patient is guided and directed more easily Difficult to guide and direct the patient
Tracings made away from the centre of rotation Tracings made closer to the centre of rotation
Examples: Gysi, Hight and Stansberry tracers Examples: Seidel, Ballard and Masserman tracers
• Earliest graphic recordings based on the studies of mandibular
movements were given by F.E. Balkwill (1866).
• First ‘needle point tracing’ was done by F. Hesse (1897).
• A. Gysi (1910) improved and popularized graphic method of
• Gysi used an extraoral tracer which had tracing plate attached to the
lower rim and the needle point attached to the upper rim.
• V.H. Sears (1926) placed the tracing plate in the upper rim and
needle point tracer in the lower rim.
• R. Hanau (1929) described the role of ‘Realeff’ which means ‘resilient
and like effect’ and argued that records made in wax had source of
errors due to this. He advocated equalization of pressure when
recording horizontal relationship.
• G.P. Phillips (1934) developed the ‘central bearing point’ based on
the concept that this device will produce equalization of pressure on
• Phillips tracers indicate the path of the condyle and direction and position
• Intraoral tracing devices are referred to as the combination of the
central bearing point with the needle point tracings, e.g. Seidel,
Ballard and Masserman tracers.
• M.M. Silvermann (1957) obtained the CR by incorporating a ‘biting
point’ on an intraoral central bearing device by means of tattooing
the alveolar ridges. Biting point was obtained by hard biting. He
believed with this the closing musculature placed the mandible in
the most retruded functional position.
• A. Obrez and C.S. Stohler (1996) stated that muscle pain had a
bearing on the static and dynamic occlusal contact relationship.
• Principles of the Gothic arch tracing were revisited in the BPS
system (biofunctional prosthetic system).
• Y Watanabe (1999) used personalized computer to analyse and
evaluate the horizontal mandibular position with the edentulous
Factors considered during graphic methods
• Stability of the record bases.
• Occlusal rims offer more resistance to horizontal movements than
• Difficult to locate the centre of arches in excessively protruded or
• Difficult to stabilize record bases on the flabby or hyperplastic
• Difficult to stabilize record bases on residual ridges with insufficient
• Recording devices may not be compatible with normal physiologic
• Tracing with only sharp apex is considered acceptable.
• Double tracings indicate that the jaw movements were not
coordinated or recordings were made at different vertical
• It is important to perform graphic tracing at the predetermined
vertical dimension of occlusion.
• Graphic methods can record the eccentric relations of the mandible
• These records are the most accurate visual means of recording CR.
Procedure of gothic arch tracing (graphic
• Vertical dimension of occlusion is predetermined.
• Tracing devices are attached to the occlusal rims and the rims are
placed in the mouth (Figs 6-11 and 6-12).
• Patient is instructed to open and close the mouth number of times
and the relationship of the stylus to the table which is coated with
black wax or soot is evaluated.
• It is made sure that pin is the only point of contact between the
• First the patient is instructed to make the maximum anteroposterior
movement of the mandible to establish the protrusive range.
• The patient then moves the mandible backwards in a retruded
• From the retruded position, the patient is instructed to move the jaw
laterally either to the right or left and to stop.
• The stylus is elevated and the patient is instructed to bring the
mandible back to the retruded position.
• Then the patient moves the jaw to the opposite side (either left or
• The relationship at the initial point of contact to the apex of the
• The procedure may be repeated until a sharp well-defined tracing is
• Ney’s mandibular excursion guide can be used to train the patient to
make appropriate mandibular movements.
FIGURE 6-11 Tracing devices attached to occlusal rims: (A)
central bearing pin; (B) central bearing plate.
FIGURE 6-12 Tracing devices placed in patient’s mouth.
Importance of Gothic arch or needle point or arrowhead tracings or
• Needle point tracing is basically a single representation of the
position of the mandible and its movement in the horizontal plane.
• Dull or rounded apex of the needle point tracing is not indicative of
• Sharp apex indicates the retruded position of the mandible, i.e. the
condyles are properly located in their glenoid fossae (Fig. 6-13).
• If the condyles do not pivot or do not have centres from which
lateral movements are made, a faulty tracing will be obtained.
FIGURE 6-13 Gothic arch tracing should have sharp apex.
Drawbacks of the needle point tracings
• It is relatively time consuming.
• It requires well-defined, nondisplaceable upper and lower alveolar
ridges to allow stable and retentive acrylic bases.
• Large tongue can cause movement of the base during tracing.
• True excursive movements are difficult for the patient to repeat.
• Too much cooperation from the patient is required.
• Tracing restricts the available tongue space which may produce
Functional chew-in record is defined as ‘a record of the movements of the
mandible made on the occluding surfaces of the opposing occlusal rim by
teeth or scribing studs and produced by simulated chewing movements’.
Functional methods utilize the functional movements of the jaws to
record the horizontal jaw relation. The patient is instructed to move
the jaw in protrusion, retrusion, right and left lateral position until
most retruded position is identified.
Types of functional chew-in methods:
Factors common to both the functional methods are:
• Both require a tentative interocclusal wax record of CR at the
tentative vertical dimension of occlusion.
• Occlusal rims are reduced in excess of the predetermined vertical
• Record bases should be accurately fitting and stable.
• Patient should have good neuromuscular control.
• Movable basal seat and lack of equalized pressure exerted on the
record base during eccentric movements can result in inaccurate
• M.F. Patterson (1923) used wax occlusal rims.
• A trough was made in the mandibular rim and was filled with a
mixture of plaster and corborundum paste (1:1 ratio) (Fig. 6-14).
• The patient was asked to move his/her mandible and continue the
motion until a curvature is formed on the rims.
• This is said to equalize pressure and provide uniform contacts in all
• The movements of the mandible generated compensating curves in
the plaster and the corborundum.
• When this paste is reduced to the predetermined vertical dimension
of occlusion, the patient is instructed to retrude the mandible in this
• This retruded position determines the horizontal jaw relationship
and both the rims are joined by means of staples.
FIGURE 6-14 Occlusal rims made with plaster and pumice
• It is the more commonly used functional method.
• In this method, the occlusal rims are made of compound.
• Four triangular-shaped studs with cutting edges are place in the
maxillary rim in the premolar and molar regions (Fig. 6-15).
• The rims are inserted into the patient’s mouth and the patient is
instructed to make mandibular functional movements.
• During these movements, the studs engrave four separate Gothic arch
recordings into the block of compound.
• These tracings relate to movements in three planes and are called
• These records are placed on an appropriate articulator, and the
condylar elements are adjusted accordingly.
FIGURE 6-15 Needle–House method: (A) Triangular-shaped
studs; (B) Gothic arch tracings in the lower rim.
• It is also called static recording method.
• Phillip Pfaf (1756) first described this technique of ‘taking a bite’.
• This type of record made with wax or compound was called ‘mush’
or ‘biscuit’ or ‘squash’ bite.
• G.J. Christensen (1905) used the impression wax to record centric
• Jacob Greene (1910) used impression compound along with plaster
• To get accurate results from this method, the proprioceptors and
tactile sensation of the patient should be in normal range.
• W.H. Wright (1939) believed that accuracy of records was influenced
by resiliency of the tissues, saliva films, fit of the bases and the
• W.B. Akerly (1979) described a direct tripodal method of recording
CR, which was a minimum pressure technique that could be
quickly and accurately verified.
• Tactile or interocclusal check record methods
Tactile or interocclusal check records
• The normal functioning of the patient’s proprioception and tactile
sense is important in making an accurate record.
• These records are made by asking the patient to retrude the
mandible. This gives the tentative CR. This relation is verified by
using interocclusal records and errors, if any are corrected.
No comments:
Post a Comment