Posterior Tooth Schemes by sammyc2007

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									DENT 5909 Wednesday, March 26
Lab: Proceed on Set Up #2 - Max and Mand Anteriors - Begin to set posteriors only after Forms 7 & 8 have been completed Finish Set Up #1 Practice Festooning on both #1 and the anterior of #2

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Selection of Posterior Tooth Schemes for Dentures

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Occlusal Scheme: Systematic arrangement of artificial denture teeth for function and comfort.

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Different schools of thought + Inconclusive research = Operator’s choice

“The golden rule is that there are no golden rules.” George Bernard Shaw, 1903

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Denture Success
 Adaptability  Operator

Skill (verbal and technical)  Vertical Dimension of Occlusion  Centric Relation  Esthetics  Accurate impressions  Occlusal Scheme
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Denture Success
 Adaptability  Operator

Skill (verbal and technical)  Vertical Dimension of Occlusion  Centric Relation  Esthetics  Accurate impressions  Occlusal Scheme
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Adaptability

“Patient adaptability, physically and psychologically, trumps all other factors.”

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Denture Success
 Adaptability

Skill (verbal and technical)  Vertical Dimension of Occlusion  Centric Relation  Esthetics  Accurate impressions  Occlusal Scheme
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 Operator

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Occlusal Scheme Selection



Investigators have not shown one type of denture occlusion to be :
  

superior in function safer to oral structures more acceptable to patients
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Goals of Complete Denture Occlusion

trauma to the supporting structures  Preserve remaining structures  Enhance stability  Enhance mastication  Esthetics and Speech  Decrease lateral forces to the residual ridges

 Minimize

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General Concepts of Denture Occlusion


Common Features
 



Simultaneous, bilateral posterior contact in centric relation (centric occlusion) Centralization of centric occlusal forces over the denture support tissues  Buccal-Lingually  Anterior-Posteriorly Functional anatomy is the main determinant of denture tooth position

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Patient Characteristics
 Age

ability and anatomy  Coordination/adaptability  Jaw relationship  House classification  Previous denture experience  Parafunctional habits
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 Physical

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Age: Youthful


Good
  

Coordination Musculature Adaptability Esthetics Demanding



Challenge
 



Select anatomic (cusped) posterior teeth ?
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Age: Advanced


Helpful
  

Experience Possible low expectation Esthetics Physical limitations Poor adaptability



Challenge
 



Select shallow cusps - or no cusps at all ?

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Physical condition of the patient

Patients with poor neuromuscular control have difficulty accommodating to anatomic occlusions. They are best served with monoplane occlusal schemes.

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Resorbed and/or movable ridges

These conditions: - make it difficult to obtain accurate intraoral records and - permit movement of the denture bases during function. The poorer the record base stability, the less cusp height is indicated.
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Resorbed and/or movable ridges

Such patients can be ideal candidates for lingualized occlusal schemes.

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Psychological condition of the patient

HOUSE: • Philosophic (Ideal) • Indifferent (motivation) • Critical (controlling) • Skeptical (inconclusive)

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Jaw Relationship
A

skeletal class II jaw relationship requires a non-anatomic scheme due to the large envelope of motion.  Skeletal class III patients chew vertically with little anterior-posterior movement. Most schemes can be used.  Crossbites generally require nonanatomic schemes.

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Previous denture occlusion
If the present dentures have anatomic teeth which have not been severely ground or worn and the alveolar ridges are not severely resorbed, anatomic teeth could be considered. If the existing denture teeth have been worn flat, nonanatomic teeth may be a better choice.
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Parafunctional Habits
- Chronic Bruxism

Anxious, nervous individuals are more apt to grind, which can be especially traumatic to the supporting structures when anatomic posterior denture teeth are used. They are best served with monoplane occlusal schemes.

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Posterior Occlusal Schemes Balanced Lingualized Monoplane with balancing ramps Semi-anatomic Anatomic (30 degree or higher) Monoplane Not balanced - Neutrocentric Lingualized opposing monoplane Monoplane
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Posterior Tooth Forms

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Anatomic Tooth Forms

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Anatomic Tooth Forms

Cusp Angle (33°)

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Nonanatomic Tooth Forms

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Semi-anatomic Tooth Forms

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Denture Occlusion Options
Lingualized (lingual contact)

Semi-anatomic

non-anatomic (balancing ramp)

anatomic

nonanatomic
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Non-anatomic - 0°, Flat, Monoplane

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Semi-anatomic Anatoline, 10°

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Semi-anatomic 20°

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Semi-anatomic 22°

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Anatomic 30° + , Pilkington Turner Euroline

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40 degree

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Specifically designed teeth for lingualized occlusion

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Lingual Bladed Teeth or Levin Blades

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Non-anatomic variations

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Types of Complete Denture Occlusion

 Bilateral

balance

 Neutrocentric

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Indications
Non-anatomic
• • •

Anatomic
• • •

• • •

Poor residual ridges Poor neuromuscular control (bruxers, CP etc.) Previously successful with monoplane dentures or Severely worn occlusion on previous denture Arch discrepancies Class II or III or cross-bite Potential poor follow-up

• •

Good residual ridges Well coordinated patient Previously successful with anatomic dentures Denture opposes natural dentition When cusp penetration of bolus is desired
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Non-anatomic (monoplane occlusion)
Advantages
Reduction of horizontal forces • CR can be developed as an area instead of a point • Freedom of movement • Can develop solid occlusion despite arch alignment discrepancies • Easily adapted to situations prone to denture base shifting • Easy to set and adjust teeth
•

•

•

•

Disadvantages No vertical component to aid in shearing during mastication Patients may complain of lack of positive intercuspation position? Somewhat esthetically limited (don’t look like natural teeth)

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Anatomic/semi-anatomic
Advantages •Intercuspation may be developed •Esthetically similar to natural dentition •Balanced occlusion can be achieved •Maintains some shearing ability after moderate wear
• • •

•

•

Disadvantages Difficult to set Less adaptable to arch relation discrepancies Horizontal force development due to cusp inclinations Harmonious balanced occlusion is lost with denture base settling Requires frequent followup and may require more frequent relines to maintain proper occlusion
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Occlusal Scheme and residual ridge contour

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Lingualized Occlusion

Theoretically, there should be less lateral displacement of the denture and less lateral forces during function when using lingualized posterior denture teeth.

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Lingualized Occlusion
The lingual cusp tips should be in contact with the central fossae of the opposing mandibular teeth. The cuspal inclines of the mandibular teeth are relatively flat, resulting in potentially less lateral forces and displacement during function.
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Lingualized “Balanced” Occlusion

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Lingualized Occlusion

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Lingualized Occlusion
Indications for use
High

Advantages
     

esthetic demands Displaceable supporting tissues Weak muscles of mastication Previous successful denture with Lingualized Occlusion

Good esthetics Freedom of non-anatomic teeth Potential for bilateral balance Centralizes vertical forces Minimizes tipping forces Facilitates bolus penetration (mortar and pestle effect)
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Bilateral Balance
 Anatomic

posterior teeth vs Lingualized

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Bilateral balance with anatomic denture teeth

Balancing side

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Bilateral Balanced Denture Occlusion
The stable simultaneous contact of opposing upper and lower teeth in centric relation position with a smooth bilateral gliding contact to any eccentric position within the normal range of mandibular function, developed to lessen or limit tipping or rotation of the denture bases in relation to the supporting structures.
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Bilateral Balanced Denture Occlusion
 Traditionally

bilateral balance was achieved with anatomic posterior denture teeth. However, it can be achieved with nonanatomic teeth using balancing ramps or by manipulating the compensating curve.

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Bilateral Balanced Denture Occlusion with Anatomic Posterior Denture Teeth

Protrusive
  

Balancing

Working

Bilateral Posterior Centric Contact Centralized Forces “Balanced” Occlusion to minimize tipping
Centric
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Monoplane with Balancing Ramps
Working Balancing

Bilateral balanced occlusion can also be obtained with nonanatomic posterior teeth if balancing ramps are employed. In all lateral excursions you should observe at least three points of contact bilaterally if bilateral balance is to be achieved.

Protrusive

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Lingualized Opposing Monoplane with Balancing Ramps Working Balancing



A similar concept is used when lingualized maxillary teeth oppose nonanatomic teeth in the mandible. In all lateral excursions you should observe at least three points of contact bilaterally to maintain bilateral balance.

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Monoplane Occlusion (Neutrocentric Concept)
This concept of occlusion assumes that the anteriorposterior plane of occlusion should be parallel to the denture foundation area and not dictated by condylar inclination. The plane of occlusion is completely flat and level. There is no curve of Wilson or Curve of Spee (compensating curve) incorporated into the set up. There is no vertical overlap of the anterior teeth. When using this concept of occlusion the patient is instructed not to incise the bolus. With this tooth arrangement DeVan noted that “the patient will become a chopper, not a chewer or a grinder.”
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Monoplane Occlusion (Neutrocentric Concept)

Centric

Balancing

At balancing and protrusive positions there is separation of the denture teeth in the posterior regions leading to tipping of the dentures. This may be disadvantageous in the patients exhibiting parafunctional grinding habits
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Balanced articulation is the bilateral, simultaneous, anterior and posterior occlusal contact of teeth in centric and eccentric positions.

B

W

P

C

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Hanau’s Quint
 Five

Factors Affecting Occlusal Balance

Inclination  Incisal Guidance  Occlusal Plane Inclination  Compensating Curve  Cuspal Inclination

 Condylar

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Hanau’s Quint


Inter-relationship of these five factors may be described by Theilman’s Formula

In order to maintain a balanced occlusion:

C=

Condylar Inclination x Incisal Guidance OccPlane x Cuspal Inclination x CompCurve
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Hanau’s Quint
Factors controlled by the dentist
 Of

these five factors, the patient presents you with Condylar Inclination  Occlusal Plane cannot be altered substantially since functional requirements dictate its position and orientation  The remaining three factors can be controlled by the dentist

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Hanau’s Quint
Factors controlled by the Patient Patient+Dentist Dentist

C=

Condylar Inclination x Incisal Guidance OccPlane x Cuspal Inclination x CompCurve

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Hanau’s Quint




Within the confines of esthetics and phonetics, minimize Incisal Guidance in Complete Dentures to minimize inclined tipping forces Adjust remaining factors to maintain balance

C=

Condylar Inclination x Incisal Guidance OccPlane x Cuspal Inclination x CompCurve
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Is “Balance” Necessary?

“Bolus in” “Balance out”

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Is “Balance” Necessary?
Tests of Balanced and Non-balanced Occlusions
Trapozzano, V. R.: JPD 10: 476-487, 1960.

1) No patient preference 2) Balanced = slightly more efficient 3) Percentage of patients using eccentric movements during mastication is small
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Is “Balance” Necessary?
“Simplification of Occlusion in Complete Denture Practice: Posterior Tooth Form and Clinical Procedures”
Dale Smith: DCNA 14: No. 3; July, 1970.

1) Advocates cuspless teeth primarily for ease of use 2) May use balanced occlusion but can’t prove that it is necessary
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See you in Lab

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