Bennett angle is defined as ‘the angle formed between the sagittal plane
and the average path of the advancing condyle as viewed in the horizontal
plane during lateral mandibular movements’. (GPT 8th Ed)
• For the articulators to simulate the jaw movements, the location of
the axis of rotation, establishment of the horizontal and lateral
condylar guidances and the provision for the Bennett shift should
• Bennett movement was first described by Dr Norman Bennett in 1908
• He showed that the working side condyle moved outwards (bodily
shift) during the lateral movement of the mandible in the frontal
• The amount of the medial movement of the balancing condyle
during the lateral excursion governs the magnitude of the direct
lateral slide of the mandible.
• Bennett shift is the bodily shift of the entire mandible when the
patient moves the mandible from its centric position into its pure
• Bennett side shift has two components, namely, the immediate side
shift and the progressive side shift (Table 5-3).
• Immediate side shift is defined as ‘the translatory portion of the lateral
movement in which the nonworking condyle moves essentially straight
and medially as it leaves the centric relation position’. (GPT 8th Ed)
• Immediate side shift occurs when the nonworking condyle moves
from CR straight medially (1.0 mm). It varies according to the shape
• Progressive side shift occurs at a rate which is directly proportional
to the forward movement of the balancing condyle on the opposite
• Immediate side sift occurs in the early stages of the horizontal
lateral movement. When the mandible moves laterally,
simultaneously the mandible translates first an average of 0.4 mm
towards the working side and then shifts to the lateral rotational
• The amount of immediate side shift varies between individuals from
0 to 2.6 mm with a mean of 0.42 (S. Hobo, 1982).
• During balancing of occlusion, if the immediate side shift is
reflected on the cuspal morphology, a centric slide is created by
grinding the slopes of the opposing teeth so that the cusp tips move
by the immediate side shift towards the working side.
• Beyond the immediate side shift, the condyles move forward,
downwards and inwards. N.F. Guichet referred this movement as
• Progressive mandibular lateral translation ‘this is the translatory
portion of the lateral movement that occurs at a rate or amount which is
directly proportional to the forward movement of the orbiting condyle’.
The value of the progressive lateral translation is about 7.5° (H.C.
• The horizontal condylar path on the nonworking side or balancing
side is composed of the immediate and progressive side shift (Fig.
• Bennett angle is the angle formed by the orbital path (horizontal
lateral condylar path) and the sagittal plane. It varies between 2°
and 44° with a mean of 16° (S. Hobo and H. Takayama, 1993).
• Bennett angle is adjusted in the articulator (semi- and fully
adjustable). It is the angle between the condylar tract of the
articulator and the midsagittal plane.
• The Bennett angle on the nonworking side controls the amount of
lateral movement of the working side on the articulator.
• Bennett shift is governed by the shape of the glenoid fossa,
looseness of the capsular ligaments and the contraction of the lateral
pterygoids in a normal subject.
• The timings of the Bennett movement occur at the rate or amount of
descent of the contralateral condyle and the rotation and lateral
shift of the ipsilateral condyle.
FIGURE 5-13 Diagrammatic representation of Bennett
movement of mandible. The working condyle (W) moves
laterally (outwards) towards right and the balancing condyle
FIGURE 5-14 Horizontal lateral condylar path. ISS,
immediate side shift; PSS, progressive side shift; BA, Bennett
DIFFERENCES BETWEEN IMMEDIATE SIDE SHIFT AND
Immediate Side Shift Progressive Side Shift
Takes place before rotation of the condyles Accompanies rotation of the condyles
It is an instantaneous side shift Gradual side shift
It is measured at the horizontal plane Measured at the sagittal plane
Measured in millimetres, usually less than 2 mm Measured in degrees, value usually less than 20°
The balancing condyle moves straight and
medially from the centric position
Occurs at a rate which is proportional to the forward
movement of the balancing condyle
• Arcon articulators contain the condylar guidance within the upper
member and the condylar elements within the lower member.
• Functional articulation is the occlusal contact of the maxillary and
mandibular teeth during mastication and deglutition.
• Bennett angle is formed between the sagittal plane and the orbital
path (horizontal lateral condylar path). Average Bennett angle is
• Bonwill triangle is a 4-inch equilateral triangle bounded by lines
connecting the contact points of the incisal edges of mandibular
central incisors to each condyle and from one condyle to the other.
• Frankfurt horizontal plane (FH plane) is a horizontal plane which
is established by joining the line between the lowest point on the
margin of the orbit to the highest point on the margin of the
• Bonwill triangle was first given by W.G.A. Bonwill in 1858.
• Fischer’s angle is the angle formed between the sagittal protrusive
condylar path and the sagittal lateral condylar path. Its average
• Pantographic tracing is the graphic record of the jaw movements
recorded in all the three planes, i.e. horizontal, sagittal and frontal
with the help of styli on the recording tables of the pantograph or
by means of electronic sensors.
• The articulation of natural dentures in the patient mouth is called
• Dummy dentures used for preliminary work in denture
construction are called occlusal rims.
• Pure hinge movement occurs at the terminal hinge position.
• Bennett shift of the mandible is the direct lateral shift of the condyle
• Kinematic facebow is attached to the lower rim.
• Balkwill’s angle is the angle formed between the occlusal plane and
• Average progressive Bennett shift is 7.5º.
• Average immediate Bennett shift is between 0 and 2.5 mm.
• The intercondylar distance in Whip-Mix articulator can vary
• RUM position (rearmost, uppermost, midmost condylar position) of
the condyles was proposed by C.E. Stuart (1969). It was considered
a physiologic condylar position, harmonious with the centric
Maxillomandibular relationship
Criteria for Selecting Record Bases, 100
Materials for Record Bases, 100
Stabilization of Record Bases, 101
Occlusal Rims and Their Importance, 101
Factors Affecting Fabrication of Rims, 102
Physiological Rest Position, 104
Factors Influencing the Physiological Rest
Niswonger’s Method of Recording Rest
Freeway Space or Interocclusal Rest Space, 109
Silverman’s Closest Speaking Space, 110
Method to Record Closest Speaking
Effects of Altered Vertical Dimension, 111
Effects of Excessively Increased Vertical
Effects of Excessively Decreased Vertical
Methods of Retruding Mandible in Centric
Factors Affecting Centric Relation Records, 113
Concepts of Centric Relation Records, 113
Graphic Method of Recording Centric
In an edentulous patient, removal of all the teeth leaves a space
between the two residual ridges which was previously occupied by
teeth and supporting structures. The record bases and occlusal rims
replace these structures and the teeth while establishing the
One of the primary requirements to establish the correct jaw
relation is to fabricate an accurate record base.
– ‘A temporary form representing the base of a denture which is used for
making maxillomandibular (jaw) relation records and for arrangement of
It is a working matrix for recording the jaw relation registrations
and for setting the teeth. These are not just static devices but an
important means of communication between the dentist and the
patient and between the dentist and the laboratory technician.
Criteria for selecting record bases
• Record bases should be dimensionally stable both in the mouth and
• These should be well adapted and accurately formed on the cast.
• These should be free of voids or sharp projections on the impression
• Extent and shape of the borders should resemble the finished
• These should provide enough space for teeth arrangement.
• These should be fabricated from materials which are dimensionally
• These should be easily removed from the cast and from the mouth.
There are several materials used for fabricating the record bases.
There are two types of record bases:
Materials used for temporary record bases:
• Vacuum-formed vinyl or polystyrene
Materials used for permanent record bases:
Ideal requirements for materials
The materials should fulfil certain criteria for their selection as
• These should be rigid even in thin sections.
• These should readily adapt to the required shape and contour.
• These should not distort during fabrication.
• These should not exhibit flow at mouth temperature.
• These should be biocompatible and nonreactive to the tissues.
Additional stability can be provided to the record bases by using:
• Light-bodied rubber base impression material
Occlusal rims and their importance
Occlusal rims are defined as ‘occluding surfaces fabricated on interim or
final denture bases for the purpose of making maxillomandibular relation
records and arranging teeth’. (GPT 8th Ed)
Occlusal rims are usually made of wax which are used to establish
an accurate maxillomandibular relationship and for arranging teeth
on temporary denture base to form trial dentures (Fig. 6-1).
FIGURE 6-1 Well-adapted record base with occlusal rims.
• Help in determining the length and width of artificial teeth
• Midline of the arch used as a guideline to arrange maxillary central
• Provide proper cuspid eminence
• Provide space for teeth arrangement
Factors affecting fabrication of rims
The following four factors are important during fabrication of occlusal
(i) Relationship of natural teeth to alveolar bone
(ii) Relationship of occlusal rims to residual alveolar ridge
(iv) Clinical guidelines for occlusal rims
Relationship of natural teeth to alveolar bone
Artificial teeth should be placed in the same position as occupied by
• Maxillary anterior teeth are inclined labially and provide support to
the upper lip and the corners of the mouth.
• Incisal edge of the upper anterior teeth approximates the vermillion
• Mandibular incisors are inclined labially and support the lower lip.
• Incisal edge of the lower anteriors is 1–2 mm behind the lingual
surfaces of the maxillary incisors.
• Maxillary posterior teeth are buccally inclined, whereas the
mandibular posterior teeth are inclined lingually.
• Maxillary buccal cusps usually project 2–3 mm beyond the buccal
cusps of the mandibular teeth in occlusion.
Relationship of occlusal rims to residual alveolar
• Occlusal rims reproduce the location and dimensions of the natural
teeth and their relationship to the anatomic structures.
• Artificial teeth should be arranged in position occupied by the
• Occlusal rims are used to determine the original vertical dimension
even in a resorbed ridge case.
FIGURE 6-2 Position of occlusal rims should be similar to
that of natural teeth: (A) position of natural teeth; (B) position
Clinical guidelines for occlusal rims
• Proper contour of the occlusal rims is determined by carefully
observing the nasolabial sulcus, mentolabial sulcus, the philtrum
• If the occlusal rims do not provide proper lip support, there will be
deepening of the nasolabial and mentolabial sulci.
• Anterior length of maxillary rim is adjusted 1–2 mm below the
lower edge of the lip. This lip position is called the low lip line.
• Maxillary posterior plane is adjusted such that the height in the first
molar region is one quarter inch below the Stenson’s duct.
• Upper anterior plane should be parallel to the interpupillary line.
• Upper posterior plane should be parallel to the Camper’s line (line
projected from the ala of the nose to the superior edge of the tragus
• Cuspid eminences are marked by placing lines at the corners of the
mouth which represents the approximate location of the distal
• Posterior part of the lower occlusal rim extends to two-thirds the
• Posterior to the cuspid area, the lower rims should be located over
the centre of the crest of the ridge.
FIGURE 6-3 Relationship between interpupillary line,
Camper’s plane and the occlusal plane (anterior occlusal
plane should be parallel to interpupillary line; posterior
occlusal plane should be parallel to Camper’s plane).
• Vertical height of the maxillary rim in the anterior is approximately
22 mm from the reflection of the cast.
• Width of the rim in anterior region is 5 mm and in posterior region
• Occlusal rim in the posterior region measures approximately 18 mm
• Anterior rim is labially inclined and the anterior edge of the rim in
the midline is approximately 8–10 mm from the incisive papilla
FIGURE 6-4 Dimension of maxillary and mandibular rims.
FIGURE 6-5 Width of the maxillary and mandibular rims.
• Anterior vertical height is 6–8 mm when measured from crest of the
ridge and 18 mm when measured from the depth of the sulcus in
• Width of the rim in anterior region is approximately 5 mm and in
• This is a commonly used method.
• A sheet of wax is softened over the flame and is
• Care is taken to avoid trapping of air bubbles
• The rolled wax is shaped in the form of cylinder.
• This cylinder of wax is placed on the record base
and is adapted and contoured to the shape of the
• Preformed occlusal rims of varied consistency, i.e.
• These are preformed rims which are placed on the
record bases and contoured according to the shape
• Alternately, metal occlusal rim formers can be used
to fabricate occlusal rims from base plate wax or
Physiological rest position is defined as ‘the habitual postural position of
the mandible when the patient is sitting comfortably in the upright position
and the condyles are in a neutral unstrained position in the glenoid fossae’.
It is also called the rest position or postural position of the mandible or
the vertical dimension of rest. This is the position of the mandible in
relation to the maxilla when the maxillofacial musculatures are in a
state of tonic equilibrium. This position is influenced by the muscles of
mastication and muscles involved in speech, swallowing and
There are two main hypotheses about the postural position of the
mandible. One involves an active mechanism and other involves a
• According to the active mechanism, this position is assumed when the
muscles that close the jaws and that open the jaws are in a state of
minimal contraction to maintain the posture of the mandible.
• The second hypothesis which is the passive mechanism states that the
elastic elements of the jaw musculature, and not any muscle
activity, balance the influence of gravity.
Significance of the Physiological Rest
• It is bone–bone relation in vertical direction.
• In absence of the pathosis, the relation is fairly constant throughout
• It is measurable and repeatable position within acceptable limits.
• It determines vertical dimension of occlusion.
• It is essential for health of the basal tissues.
• It gives rest to muscles and safeguards against fatigue.
• It prevents soreness and helps in minimizing residual ridge
Factors influencing the physiological rest position
• Role of periodontal ligament
• Teeth: Space between teeth is essential when mandible is at rest. If no
space is available between teeth in dentures, the patient will
complain of discomfort, pain and generalized hyperaemia.
• Muscles of facial expression
• Gravity: Position of the mandible is influenced by gravity.
• Postural position: The patient should sit upright with the head erect,
looking straight ahead when jaw relations are recorded.
• Psychic factor: Rest position is relaxed position of the mandible.
Values of measurements obtained are questionable when patient is
tensed, nervous, tired or irritable.
• Neuromuscular disorder: It is difficult to determine
maxillomandibular relations with such patients. The dentist should
have patience and be considerate to such patients.
Niswonger’s method of recording rest position
• This method was given by M.E. Niswonger and M.J. Thompson in
• The patient is asked to sit upright with head unsupported in relaxed
• Two arbitrary points are marked with indelible pencil, one at the
base of the nose and another at the chin.
• Upper and lower rims are inserted and the patient is asked to look
straight and repeatedly swallow and relax.
• The distance between the two points is measured and the procedure
is repeated till two measured values coincide.
• After relaxation is obvious, the lips are carefully parted to evaluate
the amount of space between the rims.
• This space in the rest state is between 2 and 4 mm when viewed in
the premolar region. It is called the freeway space.
• The interarch space and rest position are measured by using
indelible dots or adhesive tape on the face.
• Vertical dimension at rest (VDR) is determined by using a formula:
• If freeway space is more than 4 mm, the vertical dimension in
occlusion (VDO) is considered too small and if the space is less than
2 mm, the VDO is considered too large.
• It is important to record adequate interocclusal space when the
• Although it is not an accurate method but when used with other
methods, it will aid in recording proper maxillomandibular relation.
It is defined as ‘a registration of any positional relationship of the mandible
relative to the maxillae, made at any vertical orientation’.
The distance between two selected anatomic or marked points
(usually one on tip of the nose and the other upon the chin), one on a
fixed and one on a movable member.
• Vertical jaw relation can also be defined as the amount of separation
between the maxilla and mandible in a frontal plane.
• This record provides the optimal separation between the maxilla
• If this record is not measured accurately, the joint will be strained
(overextended or underextended).
• The vertical separation between the maxilla and the mandible
depends on the TMJ and the muscles of mastication.
• If the vertical dimension is altered, there will be severe discomfort in
both the TMJ and muscles of mastication.
• This relation is the easiest to record but is very critical, as errors in
vertical dimension are the first to produce discomfort and strain.
Objectives of recording optimal vertical
• To maintain aesthetic harmony of the face
• To satisfy functional requirements
• To provide comfort to the TMJ, masticatory muscles and residual
Methods of Determining Vertical Relations
• Distance of incisive papilla from mandibular
(ii) Measurements of the former dentures
(ii) Phonetics and aesthetics as guides
(iv) Tactile sense or neuromuscular perception
Distance from incisive papilla from mandibular incisors
• Incisive papilla is a stable landmark that does not change a lot with
the resorption of the alveolar ridges (Fig. 6-6).
• The distance between the incisive papilla and the lower incisors will
• The incisal edges of the maxillary central incisors are usually 8–10
mm anterior to the centre of the incisive papilla.
• The average vertical overlap between the upper and lower incisors
is, therefore, 2 mm (overbite).
FIGURE 6-6 Incisive papilla is a stable landmark on the
• The residual ridges are parallel to each other during occlusion in
• This factor can be used to determine the vertical dimension at
• Both the alveolar ridges when parallel to each other at vertical
dimension of occlusion enhance the stability of the denture.
• The mandible of the patient is adjusted parallel to the maxilla.
• The position associated with a 5° opening of the jaw in the posterior
region usually gives a correct amount of jaw separation (Sears).
• This method is not reliable in patients who have lost their teeth at
Measurements of former dentures
• Patients’ existing dentures are valuable aid in determining the
• Boley’s gauge is used to measure the distance between the borders of
the maxillary and mandibular dentures when in occlusion.
• If the distance is less, the corresponding change is made in the new
• Profile radiographs of face may be used to determine vertical
• Inaccuracies of techniques and magnification factor limit the use of
• Dentulous patient’s casts are mounted onto the articulator using
• Occlusal record with the jaws in correct centric relation (CR) is used
to mount the mandibular casts.
• After extraction of the teeth, the edentulous casts are mounted onto
the articulator and the interarch distance is compared.
• Usually the edentulous ridges are parallel to each other at the
correct vertical dimension of occlusion.
• This method is valuable in the patients where residual ridges are not
sacrificed during teeth removal.
The distance between the base of the nose and the undersurface of the
chin is measured by means of pair of calipers or divider before the
teeth are extracted (Fig. 6-7).
FIGURE 6-7 Facial measurements made with calipers.
• An accurate reproduction of the profile can be cut out in cardboard
or contoured in wire from patient’s photograph.
• This silhouette acts as a template.
• It can be repositioned to the face after the vertical dimension has
been established at the initial recording and when the artificial teeth
• The profile photographs with teeth in maximum intercuspation are
• Measurements of the anatomic landmarks on the photographs are
compared with those on the face during wax try-in and when
interocclusal records are made.
• A recent full face photograph of the patient is obtained when patient
• According to W.H. Wright, a ratio exists between the interpupillary
distance and brow to chin distance in natural teeth.
• It is not a reliable method.
• Willis observed that the distance from the base of the nose to the
lower edge of the mandible is equal to the distance between the
pupil of the eye and rima oris.
• These facial distances are measured with the help of Willis gauge.
• It is also called eye-lip-nose-chin method.
• The vertical dimension is acceptable, if both these facial distances
• It is difficult to generalize the anthropometric measurements.
• Soft tissue landmarks can vary among individuals.
• Prior to extraction of the teeth, face mask is made with acrylic resin
after making impression of the face with alginate.
• This transparent mask is placed over the face of the patient at the
time of determining the vertical dimension in edentulous jaws.
• The patient’s face will accurately fit in the mask when correct
vertical dimension is obtained.
It has already been described earlier in the chapter.
Phonetics and aesthetics as guide
• This method involves the observation of movements of the oral
tissues and analysing speech of the patient.
• It is a widely used method to determine the proper vertical
• The production of ‘ch’, ‘s’ and ‘j’ sounds bring the upper and lower
teeth very close to each other (Fig. 6-8).
• This small amount of space between the upper and lower teeth in
the anterior region is called Silverman’s closest speaking space.
• If this space is too large, the VDO is too small and if this space is too
• Phonetics can also be used as a guide by observing the anterior teeth
relation when patient makes ‘F’ or ‘V’ and ‘S’ sounds.
• The position of the upper anterior teeth is determined by the
position of the maxillae when the patient says the words beginning
• The position of the lower anterior teeth is determined by the
position of mandible when the patient says the words beginning
FIGURE 6-8 Position of upper and lower teeth during ‘S’
• It is affected by the vertical relation of the mandible to the maxillae.
• Aesthetics can be used as a guide to determine correct vertical
dimension by selecting teeth of the same size as the natural teeth
and also by correctly assessing the residual ridge resorption.
• The position of the lower jaw at the beginning of swallowing is used
as a guide to establish the vertical dimension of rest and occlusion.
• This method is based on the theory that when a person swallows,
the teeth come together with a very light contact at the beginning of
• Upper and lower record bases are inserted in the patient’s mouth.
• Soft wax cones are added to the lower occlusal rim and the patient is
given a candy to stimulate salivation.
• On repeated swallowing, the wax cones get flattened and allow the
mandible to reach the correct vertical dimension of occlusion.
• Softness of wax and the length of time this action is continued can
• Patient’s tactile sense can also be used as a guide to establish vertical
• Here, central bearing plate is attached to the lower rim and central
bearing screw is attached to the upper rim.
• The bearing screw is opened to increase the vertical dimension and
then it is slowly closed till the patient is comfortable at a particular
• This height, where the patient is comfortable, determines the correct
• Limitation: The patient may not be comfortable with the presence of
foreign objects on the palate and tongue space.
Here, excessively long occlusal rims are inserted in the patient’s
mouth and the rims are reduced stepwise till the patient perceives the
• Wax occlusal rims can be used to establish both the tentative vertical
dimension of occlusion and the tentative CR.
• After the casts are articulated, a tracing device is attached to the
occlusal rims for use in graphic tracing.
• Facial expression and aesthetics are used for final evaluation, after
teeth are arranged for trial dentures.
• This method is based on the theory that muscles are capable of
exerting maximum force from the position of the mandible, when
the teeth first contact in centric occlusion.
• The bimeter measures biting forces from which the vertical
dimension of occlusion can be determined.
• This method was suggested by R.H. Boos (1940).
• Metal plate is attached to accurately fitting maxillary record base to
provide a central bearing point.
• Vertical distance is adjusted by turning the cap.
• Patient is asked to bite on the record bases at different degrees of
• When maximum reading (power point) is indicated, plaster
registrations are made and casts are transferred to the articulator.
• Pain experienced by patient during this method influences the
Freeway space or interocclusal rest
The distance between the vertical dimension of rest and vertical
dimension while in occlusion is called the freeway space.
• In the natural dentition when the mandible assumes its
physiological rest position, there exists a space between the upper
• This interocclusal space observed in the premolar region is around
2–4 mm and is called the freeway space.
• It is used to establish the proper vertical dimension when the
muscles are in physiologic tonus and the mandible is in rest
• VDO is established by using this formula.
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