Introduction to occlusion W11 Flashcards
What is the definition of occlusion
Contact relationship between maxillary and mandibular teeth when the teeth are in function/parafunction (abnormal movement)
Position/relationship of upper and lower teeth when jaws close/are in function
Describe the difference between a static occlusal relationship and a dynamic occlusal relationship
Static: relationship when jaws are closed
Dynamic: relationship during movement
What effects occlusal contacts (extraoral and intraoral)
- Skeletal base relationship (condylar head vs slope of articular eminerce, glenoid fossa) - principle and acessory muscles of mastication/jaw movements, TMJ and skeletal relationship
- Development of maxilla and mandible
- Factors affecting development, position and shape of the teeth themselves
What does CR stand for
Centric Relation
The most centric or relaxed position of the condyle in a TMJ
- closed jaw but not clenched
Describe Centric Occlusion
Occlusal relationship of maxillary teeth with mandibular teeth when the condyles are in centric relationship
- How/position the teeth are meeting in (individual)
Describe Retruded Position (RP)
Position of condyle in posterior superior positon during TMJ movements
Describe retruded contact positon (RCP)
First contact point of teeth when the condyles are in retruded positon
Describe Intercusptal positon (ICP)
Cups to fossa relation of maxillary and mandibular teeth
Describe anterior relationship of overjet and overbite
Overjet: horizontal overlap of maxillary teeth over mandibular teeth
Overbite: verticle overlap of maxillary teeth over mandibular teeth
Describe angle classification of occlusion for…
* Class 1 malocclusion
* Class 2 malocclusion
* Class 3 malocclusion
- Class 1 malocclusion: molar relationship is normal but teeth are not symmetic in the arch
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Class 2 malocclusion: Retrognathic! Md back or Mx foward
Divison 1: teeth proclined Mx teeth Divison 2: Mx teeth retruded - Class 3 malocclusion: Prognathic! Md foward
Describe Class 1 normal occlusion
Class 1 normal occlusion: Orthognathic! Mesio-buccal cusp of the Mx 1st molar is aligned with the buccal groove of the Md 1st molar (between cusps) AND Mx canines sit between Md 1st pre-molar and Md canine
Constract dental occlusion vs skeletal relationships in terms of class 1,2 & 3
Teeth protruding or retruding
Skeletal involves jaw protruding or retruding
What are the three curves/planes of occlusion
- Curve of Wilson
- Curve of Spee
- Curve of Monsoon
Describe the curve of Spee
Anteroposterior curvature of the occlusal surfaces - tips of cupids, bicuspids and molars (anteriors-posterior arch)
If the curve was to continue it would make a circle 4 inches in diameter
Describe the curve of Wilson
Occlusion is spherical in frontal plane. Joining cusp tips of Md and Mx teeth on opposite side of arches
- enables smooth functioning of lateral excursions without interferences
Dynamic occlusion includes…
- Rotation/hinge axis
- Translation
- Lateral movements
- Complex movements
Describe dynamic occlusion on rotation/hinge axis
Opening and closing on imaginary horizontal hinge axis through head of the condyles
Describe translation
Condyle shifts foward
Describe lateral occlusion
Side to side excursions and lateral closing
Compare the working and non-working side
During mandibular lateral excursions the side of the mouth to which the mandible has moved towards = working side - usually chewing food, side of the mouth from which the mandible has moved away = non-working side.
Explain maximum opening
1st phase: hinge axis opening without moving mandible 20-25mm (HO)
2nd phase: mandible glides out, translation of condyle, further rotation (MO)
Differentiate between functional and non-functional cusps
Functional: working cusps on working side (food present)
* Usually palatal cusps of Mx posterior teeth and buccal cusps of Md posterior teeth.
Non-functional: do not occlude with the opposing teeth in centric occlusion.
* Usually buccal cusps of Mx posterior teeeth and lingual cusps of Md posterior teeth.
There are two approaches by which to manage a patients dentition to restore proper function long-term and analyse occlusion. What are they?
- Conformative approach: no change to pre-existing occlusal relationship. ‘simple’
- Re-organised approach: changing pre-existing occlusal relationship to rehabilitate major discrepancies. ‘complex’
How do you check the direct occlusal contact relationships in the patients mouth?
- Articulating paper: thin rectangular strip or U shaped placed between teeth. Thinner = more accurate.
- Shimstock: 8um thick, almost gives true occlusion
- Clinical observation: visually assess dental contacts, taking a mental note
