CSA Intro to occlusion Flashcards
What is occlussion?
Relationship of maxillary to mandibular teeth at rest and in function
What is TMJ?
joint(s) which articulate mandible to skull
What is central occlusion \or ICP (intercuspal position)
Position of mandible with mandibular and maxillary teeth cusps are maximally interdigitated regardless of condylar position
What is occluso vertical dimension ?
Vertical relationship between maxilla and mandible when teeth = in ICP
What decreases the occluso vertical dimension ?
tooth wear or missing teeth
- can be compensated by over eruption of teeth
What is resting vertical dimension ?
Vertical relationship between maxilla and mandible when resting comfortably in upright position with relaxed facial musculature
What measurement is resting vertical dimension? RVD
Arbitrary from chosen point on maxilla to one on mandible when mandible = in resting position
What is freeway space?
Space between maxillary and mandibular teeth at rest (usually 2-4mm)
How is freeway space calculated?
Calculated by vertical difference between RVD and OVD
How is RVD achieved?
• Achieved after swallowing/yawning
What is retruded contact position RCP or centric relation (CR)
Mandibular position occurring at very first contact between maxillary and mandibular teeth when condyle = in most superior and rotating around it’s terminal hinge axis
When is the most retruded position of mandible?
when initial intercuspal contact
What do condylar heads rotate around?
rearmost within their glenoid fossa and rotate around their terminal hinge axis
What is the glenoid fossa?
depression in temporal bone that articulates with mandible
What is protrusion ?
Anterior movement of mandible when teeth = in occlusion
What is terminal hinge axis?
Point where condyle rotates during rotary phase of opening mouth
When does terminal hinge axis only occurs?
when mandible = in most retruded position
What is opening of mouth?
involves 2 concurrent processes that = occur in the TMJ
What does the condyle do movement wise?
rotates and translates
What is rotation ?
condyle rotates around terminal hinge axis when in retruded position
What is translation?
Forwards/Downwards movement of condyle down articular eminence of TMJ = wider opening of jaw
What happens to condyle during translation ?
pulled forwards by lateral pterygoid muscle (a little bit by temporalis)
What is condylar guidance?
Effect of shape of articular eminence on protrusive movements of mandible
What is the result of condylar guidance?
lowering of the angle of mandible as condyle = slides down articular eminence
What are lateral excursions?
Occlusal relationship between teeth when mandible = shifted horizontally to right or left
What is the working side during lateral excursions
Side to which the mandible has moved:
What does working side occur?
during mastication depending on which side you position food with your tongue
What is the non working side?
Side away from which mandible has moved (pulled by the lateral pterygoid muscle)
What is horizontal movement guided by?
working side
What is canine guidance?
During lateral excursions, all teeth = disclude except canines on working side
What does canine guidance prevent ?
• Prevents molars/premolars from wearing/fracturing during lateral movements
What is group function ?
During lateral movements 2 or more teeth = stay in contact
When do ppl get group functions?
as they age
What is disclusion ?
Separation of teeth due to prominent tooth on tooth contact
How can disclusion occur?
- natural e.g. prominent canines/canine guidance
* unintentionally created by dentist >restoration = too ‘high’ in bite
What are parafunctions?
Tooth contacts = X involved in normal functioning of jaws i.e. mastication and speech
What is parafunction caused by
attrition (bruxism) or abrasion e.g. chewing nails/pencils, holding lip/tongue/cheek piercing in between teeth
What is bruxism ?
Subconscious, non-functional grinding of maxillary and mandibular teeth
When does bruxism occur?
night (pain in jaws in morning)
stressful time
•Toothwear, fracturing and pain in masseters/headache
How to treat bruxism?
• Treatment: Pt. education and splints (mouth guards)
What is conformative treatement?
Treatment = aimed to fit in pts. existing occlusion
What is reorganised treatment?
Treatment = aimed to change pt. occlusion
What is interference?
Any tooth that causes premature contacts causing other teeth to disclude on lateral and protrusive excursions
What causes interference ?
. ‘High’ filling X bite properly
• Could get ‘shiny spots’ on amalgam if pt. prematurely bites down on it
What is a result of shiny spots on amalgam?
teeth to ‘jolt’
- PDL on opposing tooth = could inflame and widen so incr. mobility
- Pt. may complain of sensitivity so check occlusion
What is fremitus ?
Palpable vibration or slight movement of teeth when occluded
What is overjet?
Horizontal distance between maxillary and mandibular incisal edges in ICP
What is overbite ?
Vertical distance between maxillary and mandibular incisors in ICP
What is articulating paper?
Inked paper = placed between maxillary and mandibular teeth (bitten down on)
What does articulating paper indicate?
position of tooth contacts
What is an articulator ?
Mechanical device = recreates pts. jaw- can see relationship between maxillary and mandibular teeth
What types of articulators are used by technicians ?
- Simple hinge:
- Average value:
- Semi adjustable:
- Fully adjustable
What is axiographic recording ?
Mechanical device that records condylar movements and TMJ movements etc.
What does overloading teeth mean?
- Premature contacts
- Lateral forces on posterior teeth
- Excessive (masticatory) forces due to parafunction > MOM = working harder than normal
What does bruxism cause?
- incr. wear, incr. RO fracture or rests. and teeth,
- incr. muscle/MOM pain and micro cracks in enamel
- masseteric hypertrophy in severe cases
How to avoid occlusal problems with rests?
should conform to pts. existing occlusion:
- ‘bite’ feel same after rest. as did b4 started
- Use articulating paper and ask pt. “does it feel normal?” to see if rest. = high on bite
What is the effect of high rests?
- Pain > incr. in MOM and tooth
- Mechanical failure > fractured rests, incr. wear
How to extraorally examine patients on clinic?
- MOM palpitation (masseter/temporalis) > tender where muscles originate/insert?
- TMJ during open/close of mouth
- TMJ clicking/grinding
