• When teeth are arranged on the plane, these are not inclined to form
• In the mediolateral direction, the tooth is set flat with no medial or
• Thus, this concept of occlusion eliminates any anteroposterior or
mediolateral inclines of the teeth and directs the forces of occlusion
• The patient is instructed not to bite with the anterior teeth.
• Monoplane or cuspless posterior teeth are used in this type of
• Because of this, there is no projection above or below the occlusal
• The horizontal and lateral condylar guidances of the articulator are
• To direct force towards the centre of the support and to reduce the
functional forces, the buccolingual width of the teeth and the
number of teeth are also reduced.
FIGURE 8-8 Teeth arranged in neutrocentric occlusion.
Factors influencing neutrocentric occlusion are:
• Skeletal relationship of the jaws.
• Influence of somatic nervous system to control muscle movement
• Accuracy of the denture bases.
• Stable position of the condyles in the glenoid fossa.
• It is more adaptable to unusual jaw relation such as class II and class
• It can be used with crossbite relations.
• It provides freedom in occlusion.
• It is useful in cases of poor ridges.
• It is a simplified and less time-taking technique.
• It results in poor aesthetics.
• It results in decreased masticatory efficiency.
• It results in decreased denture stability during eccentric movements.
• It is difficult to obtain balanced occlusion.
Spherical occlusion is defined as ‘an arrangement of teeth that places their
occlusal surfaces on the surface of an imaginary sphere (usually 8 inches in
diameter) with its centre above the level of the teeth’. (GPT 4th Ed)
• Spherical theory of occlusion was introduced by G.S. Monson (1918).
• This concept of occlusion was based on observations of the natural
teeth by German anatomist von Spee.
• Hagman balancer and one phase of the Pankey–Mann occlusal
reconstruction technique were based on the spherical theory of
• According to this concept, the anteroposterior and mesiodistal
inclines of the artificial teeth should be arranged in harmony with a
• The spherical theory of occlusion proposed that lower teeth move
over the surface of upper teeth as over a surface of sphere with a
• The centre of sphere was located in the region of glabella.
• The surface of the sphere passed through the glenoid fossa and
along with the articulating eminences.
• Articulators based on this theory do not have provisions for
variations in inclinations for condylar paths.
• It cannot be used in all patients due to variation in the paths of jaw
Balanced occlusion is defined as ‘the bilateral, simultaneous, anterior, and
posterior occlusal contact of teeth in centric and eccentric positions’. (GPT
‘Stable simultaneous contact of the opposing upper and lower teeth in
centric relation position and a continuous smooth bilateral gliding from this
position to any eccentric position within the normal range of mandibular
• Maximal bilateral, simultaneous contact in centric positions.
• Working contacts are present all along the working side from the
• Balancing contact in protrusive position in the molar region. Slight
variation in angulation can result in this contact.
• Balancing in the molar region in lateral position.
• Occlusal plane of the completed set up parallel to the maxillary and
Factors which aid in achieving balanced occlusion are described as
• The inclination of the condylar path.
• Angle of the incisal guidance chosen for the patient.
• Inclination of the plane of occlusion.
• The compensating curves chosen for orientation with the condylar
• Cuspal height and inclination of the posterior teeth.
• Inclination of the condylar path on the nonworking side.
• Inclination of the incisal guidance and cuspid lift.
• Inclination of the plane of occlusion on the balancing or nonworking
• Compensating curve on the balancing and the working side.
• The buccal cusp heights or inclination of teeth on the balancing side.
• The lingual cusp heights or inclination of teeth on the working side.
• The Bennett side shift on the working side.
Requirements for balanced occlusion
• All the teeth of the working side (canine to second molar) should
glide evenly against the opposing teeth.
• No single tooth should produce any interference or dislocation of
• There should be contact in the balancing side, but they should not
interfere with the smooth gliding movements of the working side.
• There should be simultaneous contact during protrusion.
• Balanced occlusion is one of the most important factors that affect
the denture stability. Absence of occlusal balance will result in
leverage forces which destabilize the denture during mandibular
• Bilateral balanced occlusion provides contact during the terminal
arc of closure to help seat the denture in a stable position during
• Balanced occlusion aids during swallowing as it allows even
• It helps in preventing the destructive lateral forces generated during
parafunctional habits such as bruxism to be transmitted to the
• It provides stability, retention and comfort.
• Dentures which are not balanced tend to move during function, this
movement or shifting of the denture base tends to abuse the
(i) Unilateral occlusal balance
(ii) Bilateral occlusal balance
(iii) Protrusive occlusal balance
• This type of occlusion has all the teeth contacting on the working
side and with no contact on the balancing side.
• This type of occlusion is not advised in complete denture fabrication
but can be used in fixed partial dentures.
• This occurs when there is bilateral simultaneous contact of the teeth in
centric and eccentric movements.
• In this, minimum of three contacts are needed to establish a plane of
• This type of balance is dependent on the interaction of condylar
inclination, incisal guidance, plane of occlusion, height of the cusp
• This type of occlusion is the most desired one in complete denture
• It enhances the denture stability in centric and eccentric movements.
• During protrusion of the mandible, there is simultaneous and
bilateral contact in the posterior and anterior teeth.
• It requires a minimum of three contacts, one on each side on the
posterior teeth and one on the anterior teeth.
• This type of balance also depends on the interaction of factors
similar to the bilateral balance (Fig. 8-9).
FIGURE 8-9 Teeth contact during protrusive balance.
• There is a simultaneous contact on the working and balancing side
• Minimum three-point contact is needed.
• Greater the number of teeth contacting, greater will be the balance.
• It is desirable in complete dentures to enhance stability.
Concepts of balanced occlusion
• A. Gysi first proposed the concept of balanced occlusion in 1914.
• He suggested that 33° anatomic teeth can be arranged under various
movements of the articulator to enhance the stability of the denture.
• F.H. French (1954) used modified French teeth to obtain balanced
• He suggested lowering of the lower occlusal plane to enhance
stability of the dentures along with balanced occlusion.
• He arranged the upper first premolars with 5° angulation, upper
second premolars with 10° angulation and upper molars with 15°
• He introduced the balanced occlusion for nonanatomic teeth using
posterior balancing ramps or an occlusal plane which curves
anteroposteriorly and laterally.
• M.A. Pleasure introduced a Pleasure curve or the posterior reverse
lateral curve to align and arrange the posterior teeth in order to
increase the stability of the denture.
• He used reverse curve in the first premolar, flat occlusal surface on
the first molar and Monson curve at the second molar to achieve
• The reverse curve helped in directing the forces of occlusion
lingually to enhance the stability of the lower denture.
• He advocated arranging teeth in a one-dimensional contact
relationship, which could be reshaped during the wax try-in to
• Rudolph L. Hanau proposed that five factors were important in
achieving balanced occlusion, which are as follows:
(v) Plane of orientation of the occlusal plane
• It is also called ‘triad of occlusion’.
• Reviewed factors of Hanau’s Quint and came to the conclusion that
only three factors were important to achieve balanced occlusion.
• He eliminated the plane of occlusion as he believed that its location
is highly variable and depends on the available interarch space.
• He suggested that occlusal plane should be located at various
heights to favour a weaker ridge.
• The other factor which he considered unimportant was the
• When the cuspal angulation that will produce balanced occlusion is
determined, the concavity or convexity of the curve can easily be
• F. Lott studied Hanau’s work and clarified the laws of occlusion by
relating them to the posterior separation that is the resultant of the
• Greater the angle of the condylar path, greater will be the posterior
separation during protrusive movement.
• Greater the vertical overlap, greater is the separation in the anterior
region and the posterior region regardless of the angle of the
• Greater the separation of the posterior teeth, greater or higher will
• Posterior separation beyond the balancing ability of the
compensating curve requires the introduction of the plane of
• Greater the separation of the teeth, greater must be the height of the
• C.O. Boucher confronted V.R. Trapozzano’s concept and proposed
the following three factors for balanced occlusion.
(i) According to him, there are three fixed factors,
namely, orientation of the occlusal plane, incisal
guidance and the condylar guidance.
(ii) Angulation of the cusp is more important than
(iii) The compensating curve enables one to
increase the effective height of the cusps without
changing the form of the teeth.
• This concept was similar to the Lott’s concept except here the plane
of orientation factor is eliminated.
• According to him, the plane of occlusion can be slightly altered by
1–2 mm in order to improve stability of the denture.
• He named other four factors as QUAD.
• The condylar guidance is fixed and given by the patient. The
balancing condylar guidance includes the Bennett shift of the
working condyle. This may or may not affect the lateral balance.
• Incisal guidance is obtained from the patient’s aesthetic and
phonetic requirements. However, it can be modified (e.g. in cases of
resorbed residual ridges, the incisal guidance can be reduced).
• Compensating curve is the most important factor for obtaining
balance. Monoplane or low cusp teeth should employ the use of
• Cusp teeth or anatomic teeth have the inclines necessary for
obtaining the balanced occlusion but are used mostly with the
Factors influencing balanced occlusion
Rudolph L. Hanau proposed nine factors that govern the articulation
of the artificial teeth, which are:
(i) Horizontal condylar guidance
(iii) Protrusive incisal guidance
(v) Buccolingual inclination of tooth axis
(vi) Sagittal condylar pathway
(vii) Sagittal incisal guidance
These nine factors were called the laws of balanced articulation.
Hanau later condensed these nine factors and formulated five factors,
which are commonly known as Hanau’s Quint.
(v) Plane of orientation of the occlusal plane
Condylar inclination (fig. 8-11)
FIGURE 8-11 Diagram showing condylar inclination which is
the only factor given by the patient.
Condylar inclination is defined as ‘the direction of the lateral condylar
• It is the only factor which is given by the patient.
• The inclination of the condylar path is determined by the protrusive
• This factor is fixed by the patient and cannot be altered by the dentist.
• The articulator is programmed using the protrusive record of the
• The occlusion set on the articulator should be in harmony with the
patient’s temporomandibular joint.
Incisal guidance is defined as ‘the influence of the contacting surface of the
mandibular and maxillary anterior teeth on mandibular movements’. (GPT
• It is called the second factor of occlusion.
• It is determined by the dentist and altered depending on the individual
• It can be set depending upon the desired overjet and overbite planned
• It is the anterior controlling factor.
• If the overjet is increased, the inclination of the incisal guidance is
• If the overbite is increased, the inclination of the incisal guidance
• The incisal guidance has greater influence on the posterior teeth
• This is because the posterior teeth are closer to the action of incisal
inclination than the action of the condylar guidance.
• During protrusive movements, the incisal edge of the mandibular
anterior teeth move in a downward and forward path
corresponding to palatal surface of the upper incisors.
• This is known as the protrusive incisal path or incisal guidance.
• The angle formed by this protrusive path to the horizontal plane is
called protrusive incisal path inclination or the incisal guide angle.
• This influences the shape of the posterior teeth.
• If the incisal guidance is steep, the compensating curve is needed to
• In a complete denture, the incisal guide angle should be as flat
(more acute) as the aesthetics and phonetics permit.
• Therefore, while arranging the anterior teeth, for aesthetics, a
suitable vertical overlap and a horizontal overlap should be chosen
to achieve balanced occlusion.
• Also, once the aesthetics is established, this factor becomes fixed.
• If the incisal guidance is steep, then to achieve balanced occlusion
steep cusps, steep occlusal plane or compensating curve is used.
• The location of the incisors is governed by various factors such as
aesthetics, function and phonetics.
FIGURE 8-12 Schematic diagram showing incisal guidance:
(A) anterior teeth; (B) incisal guide table.
Determinants of the incisal guidance are:
Plane of orientation (fig. 8-13)
Plane of orientation is defined as ‘the average plane established by the
incisal and occlusal surfaces of the teeth. Generally, it is not a plane but
represents the planar mean of the curvature of these surfaces’. (GPT 8th Ed)
• The plane of orientation should be established exactly as it was
when the natural teeth were present.
• It is established anteriorly by the height of the lower canine, which
nearly coincides with the commissures of the mouth and posteriorly
ends at the anterior two-thirds of the retromolar pad.
• It is essentially parallel to the ala–tragus line or the Camper’s line.
• It can be slightly altered and its role is not as important as other
• Tilting the plane of occlusion beyond 10° is not advisable.
• Research shows that when the occlusal plane is parallel to the ala–
tragus line, the closing force during maximum clenching is greater
FIGURE 8-13 Diagram showing height of occlusal plane.
Cusp angle is defined as ‘the angle made by the average slope of the cusp
with the cusp plane measured mesiodistally or buccolingually’. (GPT 8th Ed)
• The cusps on the teeth or the inclination of cuspless teeth are
important factors that modify the effect of plane of occlusion and
• The mesiodistal cusps lock the occlusion, such that repositioning of
teeth does not occur due to settling of base.
• In order to prevent the locking of occlusion, all the mesiodistal
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