The document discusses occlusal planes and compensating curves in relation to complete dentures, emphasizing the importance of centric relation and balanced occlusion for denture stability during mastication. It details the various compensating curves, including the curves of Spee, Wilson, and Monson, and outlines factors influencing balanced occlusion critical for prosthodontic rehabilitation. Furthermore, it highlights the significance of the occlusal plane's configuration in maintaining occlusal stability and healthy mucosa in edentulous patients.

1. OCCLUSAL PLANES &
COMPENSATING CURVES.
Presented by- Moderated by-
NAYANJIT TALUKDAR - Dr. Jogeswar Barman
Roll No.- 16 -Dr. Rajdeep Paul
2nd year BDS
Regional Dental College.

2. OCCLUSION
According to GPT 9-
The static relationship (process of closure) between
the incising or masticating (occluding) surfaces of the
maxillary or mandibular teeth or tooth analogues.

3. DIFFERENCE BETWEEN NATURAL TEETH AND COMPLETE
DENTURE OCCLUSION.

4. CENTRIC RELATION
 It is the maxillomandibular relationship, independent of tooth
contact, in which the condyles articulate in the anterior-
superior position against the posterior slopes of the articular
eminences, and are resting in the most retrussive unstrained
position in the glenoid fossa.

5.  It is the occlusion of the opposing teeth when the mandible
is in centric relation, which may or may not coincides with
the maximum intercuspation during swallowing and the
terminal position of a masticatory stroke.
CENTRIC OCCLUSION

6. TYPES OF CD OCCLUSION
* Balanced occlusion
* Monoplane occlusion
* Lingualized occlusion

7.  Definition:- It is defined as the bilateral simultaneous, anterior
and posterior occlusal contact of teeth in centric and eccentric
positions.
- GPT-9
 Balanced occlusion in complete denture is unique, as it
doesn't occur with the natural teeth.
 If it occurs with the natural teeth, it is considered as a
premature contact on nonworking side and is considered as
pathologic.
BALANCED OCCLUSION

9. SIGNIFICANCE.
 This concept was originally put forth to enhance the retention as well as the
stability of the denture during mastication.
 It is deemed necessary during many excursive movements like swallowing
saliva, closing to reseat dentures and bruxism, performed by patients in
between meals.
 If balance is not present, the denture base could tip, shift or torque on their
foundation during the eccentric movements and cause soreness and
inflammation, leading to accelerated bone resorption.
 Equal contact of all posterior teeth in centric relation is definitely essential
to the healthy mucosa, though the same cannot be stated for contact in
eccentric relations.

10. FACTORS AFFECTING BALANCED
OCCLUSION.
 Condylar guidance.
 Incisal guidance.
 Orientation of the occlusal plane.
 Compensating curves.
 Cuspal inclination.

11. IMPORTANCE.
The determination off the occlusal plane is one of the most important steps in
prosthodontics rehabilitation of edentulous patients. The position of
occlusal plane forms the basis for ideal tooth arrangement.
The 3D arrangements of dental cusps and incisal edges in the natural human
dentition are classically described as spherical, with the occlusal surface of
all teeth touching a segment of the surface of the sphere, called as Curve of
Monsoon. It is divided into an anteroposterior curve and a mediolateral
curve called as curve of Spee and curve of Wilson respectively.
Reestablishment of these curves of natural dentition is essential during
rehabilitation of a patient in prosthodontics. Replacement of natural
occlusal curves with artificial teeth are collectively known as compensating
curves which hold an important place in complete denture fabrication.

12. OCCLUSAL PLANE.
Occlusal plane or plane of occlusion refers to an imaginary average
plane that is theoretically established by the incisal edges of the
incisors and the tip of the occluding surface of the posterior teeth.
-- GPT-9
 Generally, it is not a plane but represents the planar mean of
the curvature of these surfaces.

14. ORIENTATION.
 It is established anteriorly by the height of the lower canine,
which nearly coincides with the commissure of the mouth.
 Posteriorly, it is established by the height of the retromolar
pad.
 It is also related to the ala-tragus line.
 It must be orientated in the same relation as when natural
teeth existed, and hence, there is not much scope to
manoeuvre this factor

15. SIGNIFICANCE OF OCCLUSAL PLANE.
 The configuration of the occlusal plane is important
as slight variation will lead to occlusal instability.
 It should be in harmony with the other components
of the masticatory system.
 It forms the basis by which occlusal surfaces of teeth
can be related to one another and to other structures
of the head.

16. DIFFERENT OCCLUSAL PLANES.
Thayers in 1990 AJO has given three different
occlusal planes . They are-
 Bisected occlusal plane.
 Functional occlusal plane.
 Lower incisor occlusal plane.
 Upper/lower occlusal plane.

17. COMPENSATING CURVES.
They are defined as the anteroposterior curvature (in the median
plane) and the mediolateral curvatures (in the frontal plane)
within the alignment of the occluding surfaces and the incisal
edges of artificial teeth that is used to develop balanced
occlusion.
--- GPT-9.
The arc introduced in the construction of complete removable dental
prosthesis to compensate for opening influences produced by the
condylar and incisal guidance's during lateral and protrusive jaw
movements.
--- GPT-9.

18.  They are determined by the inclination of the posterior teeth
and their vertical relationship to the occlusal plane.
 This results in curve that is in harmony with the mandibular
movements as dictated by condylar guidance – both
protrusive and lateral.
 A steep condylar guidance requires steep compensating
curve for occlusal balance; otherwise, it will lead to loss of
balancing molar contact during protrusion and lateral
excursion.

19. ANTEROPOSTERIOR CURVE
• It runs in an anteroposterior direction an helps in
obtaining protrusive balance
MEDIOLATERAL CURVE
• It runs in a lateral direction from one side of the arch to
the other and helps in obtaining lateral balance.
The curves that assist in producing balanced occlusion are
as follows-

20. CURVE OF SPEE.
 It is the anatomic curve established by the occlusal alignment of the
teeth, as projected to the median plane, beginning with the cusp tip
of the mandibular canine and following the buccal cusp tips of the
premolar and molar teeth, continuing through the anterior border of
the mandibular ramus, ending with the anterior-most portion of the
mandibular condyle.
-- GPT-9
 It was first described by Ferdinand Graf Spee, German anatomist,
in 1890.
 Spee suggested that this geometric arrangement is the most efficient
pattern for maintaining maximum tooth contact during chewing &
considered as an important tenet in denture construction.

22.  This curve assist in obtaining protrusive balance.
 Without this curve, it would be necessary to tilt the entire
occlusal plane at an angle and raising it distally, to obtain
balance. This will destabilize the upper denture and cause
damage to the rugae area, increasing bone resorption in this
area.
 This radius or steepness of the curve necessary to achieve
balance is dependent on the incisal and condylar guidance. It
is functionally and mechanically advantageous to keep it as
modest or shallow as possible.

23.  In the theory that the occlusion should be spherical, the curvature
of the cusps as projected on the frontal plane expressed in both
arches; the curve in the mandibular arch being concave and the
one in the maxillary arch being convex.
-- GPT-9
 It is named after George Wilson, who described it in 1911.
 The curve of Wilson also permits lateral mandibular excursions
free from posterior interferences.
CURVE OF WILSON.

24. Curve of Wilson.

25.  This is curve that is convex downwards. It is used to arrange the
molar teeth.
 This curve results from the lingual inclination of the mandibular
posterior teeth; making the lingual cusps lower than the buccal
cusps and bringing them in heavy occlusal contact with the
upper buccal cusps during lateral movements of the working
side, which are placed higher than its palatal cusp due to the
buccal inclination of maxillary arch.

26.  It is a curve of occlusion that is convex upwards.
 This is used to arrange the 1st premolars.
 1st proposed by Avery Brothers.
Reverse curve or Anti-Monsoon curve.

27.  This is the curve of occlusion in which each cusp and incisal
edge touches or conforms to a segment of the surface of a
sphere 8 inches in diameter with its centre in the region of the
glabella.
-- GPT-9
 This curve in three dimensions is a combination of the ‘curve of
Spee’ and ‘curve of Wilson’.
 This curve is named after George S. Monson in 1932.
CURVE OF MONSOON.

29.  Bonwill was the 1st to describe the dental
arches, noted that an equilateral triangle
of 4 inch sides existed between the
centres of condyles and the mesial
contact areas of the mandibular central
incisors.
 In 1932, Monsoon, used Bonwill’s
triangle and proposed a theory of a
sphere and curve formed from that
sphere was later known as Curve of
Monsoon.
BONWILL TRIANGLE.

30.  This is a helicoid curve of occlusion that, when viewed in the
frontal plane, conforms to a mediolaterally convex curve in
which the lingual surfaces of the teeth are more coronal to the
buccal surfaces, except for the last molars, which reverse that
pattern.
-- GPT-9
 1st proposed by Max Pleasure in 1937.
 This is a combination of Monsoon and anti-Monsoon curves.
Hence, it is not a single curve but a combination of curves.
 It is used for arranging non-anatomic teeth in balanced
occlusion.
CURVE OF PLEASURE.

32.  The premolars and 1st molars are set in a reverse curve to prevent buccal
tipping and seat the denture.
 2nd molars are set in a conventional Monsoon’s curve to provide eccentric
lateral balance.
 This curve increases the total efficiency and stability of the upper
dentures during speech, laughter, coughing, sneezing, etc.
 Enhanced stability of the lower denture during closure against a morsel of
food.
 Unimpaired balancing contacts, increased cutting efficiency because of
longitudinal sliding movements of the lower cutting ridges.
 Reduced occlusal pressure and tissue trauma.