lec 11 Flashcards
Occlusion
defined as the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues.
ARTICULATION
defined as the static and dynamic contact relationship between the occlusal surfaces of the teeth during function.
CENTRIC OCCLUSION
occlusion of opposing teeth when the mandible is in centric relation. This may or may not coincide with the maximal intercuspal position.
an occlusion other than centric occlusion. This includes lateral and protrusive occlusion.
ECCENTRIC OCCLUSION
- refers to the occlusion existing when the mandible is in the protrusive position.
PROTRUSIVE OCCLUSION
- refers to the occlusal contacts occurring when the mandible is in the right or left lateral positions.
LATERAL OCCLUSION
Reasons for using CR in edentulous patients: (FMHCC)
- Allows function to all positions.
- Conducive to health (non-pathologic) Brill et al - pain and loss of occlusal sense when not in CR Reynolds - 24% of normal population has CR=CO
- Convenient - relatively centered condyles (Celenza)
- More reproducible (Grasser) - easier to set a stable maximum intercuspation
- CR is not far from CO at same occlusal vertical dimension (Wilson and Nairn)
How to obtain CR (6)
- The patient should be placed in a slightly supine, position.
- Place notches in the occlusion rim to aid in stabilizing the record bases with index fingers on the rim, and thumbs under symphysis.
- Jiggle the lower jaw - the mandible should freely arc.
- Allow the patient to close the last portion.
- DO NOT PUSH THE MANDIBLE or dislodge the record base.
- The registration media must be dead soft, when the patient close into it.
bilateral simultaneous, anterior and posterior occlusal contact of teeth in centric and eccentric position.
BALANCE OCCLUSION (ARTICULATION)
the side towards which the mandible moves in a lateral excursion.
WORKING SIDE
that side of the mandible that moves toward the median line in a lateral excursion. In other words, the side opposite to the working side.
BALANCING SIDE (NONWORKING
MAXIMAL INTERCUSPATION (MAXIMAL INTERCUSAL POSITION)
the complete intercuspation of the opposing teeth independent of condylar position, sometimes referred to as the best fit of the teeth regardless of the condylar position.
ARTIFICIAL OCCLUSION vs. NATURAL OCCLUSION
ARTIFICIAL OCCLUSION
1. Supported by a denture base placed on slippery mucosa
2. Moves as a unit on their base
3. Malocclusion evokes immediate instability and pain
4. Forces acting on a complete denture affect the whole base
5. Nonvertival forces are usually not well tolerated
6. The second premolar area is preferred for mastication (it is the anteroposterior center of the occlusal table); mastication in the second molar region can cause shifting of the bases.
7. Bilateral balance is usually considered necessary for denture stability
8. Poor feed-back mechanism, so neuromuscular control is compromised
NATURAL OCCLUSION
1. Supported by roots which are firmly anchored to the bone
2. Moves independently in their socket
3. Malocclusion may remain uneventful for years
4. Occlusal forces affect only the concemed teeth
5. Nonvertical forces are tolerated much better
6. Mastication is usually done in the second molar region.
7. Bilateral balance is not naturally found and is considered detrimental
8. The proprioceptive mechanism enables the patient to avoid prematurities and improve control.
FUNCTIONS OF COMPLETE DENTURE OCCLUSION (MHSHC)
1) Improve masticatory function.
2) Minimize harmful nonvertical or lateral forces.
3) Contribute to the stability of the denture base.
4) Contribute to the health and preservation of the alveolar bone and soft tissue.
5) Maintenance of the comfort and well-being of the patient.
OCCLUSAL SCHEMES IN THE COMPLETE DENTURE
- Balance Occlusion
- Nonbalance Occlusion
- Lingualized Occlusal Scheme
- Functionally Generated Occlusal Scheme
BALANCE OCCLUSION (BALANCE ARTICULATION)
the bilateral simultaneous, anterior and posterior occlusal cont act of teeth in centric and eccentric position.
* Ideal occlusal scheme for complete denture.
BALANCE OCCLUSION (BALANCE ARTICULATION) Objectives:
(1) To improve stability, thereby improving function of the denture.
(2) To reduce resorption and soreness by improving function and distributing stresses.
(3) To improve oral comfort and well being of the patient.
MECHANICS OF BALANCE OCCLUSION
- In natural dentition, when the mandible is protruded so that the incisal edges of the upper and lower teeth contact, there is a gap between the upper and lower teeth in the posterior part (Christensen’s phenomenon) which can cause flipping or instability of the denture. Thus, stability of the denture can be improved if there are simultaneous anterior and posterior contacts when the mandible is protruded.
- When the mandible is moved to one side (working side), a space may be observed on the opposing side (balancing side) and this can lead to instability. Giving simultaneous occlusal contacts on both sides of the arch (lever balance).
FACTORS AFFECTING BALANCE OCCLUSION
- Condylar Guidance
- Incisal Guidance
- Plane of Occlusion
- Compensating Curbes
- Cuspal Inclination
CUSPAL HEIGHT/ INCLINATION
- It is the smooth gliding of the cusp tips along the cusp inclines of the opposing teeth that provide balance articulation.
- Cuspal inclines should not be too steep as it can increase lateral forces.
- It is possible to decrease cuspal height by using compensating curves. The compensating curves can be adjusted to make cuspal slopes parallel to the mandibular path.
NONBALANCE OCCLUSION (NEUROCENTRIC CONCEPT)
- Multiple uniform contact in centric relation was sufficient.
- To avoid harmful lateral forces, nonanatomic teeth were preferred.
LINGUALIZED OCCLUSAL SCHEME (PAYNE, 1941)
- In this concept, the teeth are not set more towards the lingual, but rather the teeth are modified and inclined in such a way that the forces are directed towards the lingual side.
- It was claimed that this improved the stability of the lower denture.
‘mortar and pestle’ effect.
- The maxillary palatal cusps are set into the lower central fossa. The buccal cusps are kept out of contact.
FUNCTIONALLY GENERATED OCCLUSION
- In this occlusion scheme, the maxillary cusps are carved out pathways in the wax placed on the lower occlusal table. Later the wax containing this pathway is replaced with cast gold or cobalt chromium alloy.
