Occlusion 2 Flashcards
In what 2 stated can you exmaine the occlusion of a patient?
- static
- dynamic
When marking tooth contacts what should you use?
2 diff colours of articulating paper (one colour for static occlusion and one for dynaminc)
When should you mark tooth contacts?
Before:
- Preparing a tooth
- Removing a restoration
After:
- Placement of a crown
- Placement of a restoration
Why do you want to mark tooth contacts before preparing a tooth?
- You want to look and see if your work will interfere with any occlusal contacts
In terms of changing occlusal contacts, you want to check them beforehand and then what would you decide?
If the occlusal scheme is good then would conform to this occlusion (try recreate it)
What can be assessed in the static occlusion?
- Incisor Relationship
- Molar relationship
- Overjet/Overbite
- Cross bites
- Open bites
- Individual tooth contacts
- RCP – ICP slide (freedom in centric)
What is the definition of a functional cusp in ICP?
Cusps that occlude with the opposing teeth in the intercuspal position
What are the functional cusps in a dentition?
- Are the palatal cusps of the upper posterior teeth and the buccal cusps of the lower posterior teeth
What is the definition of non-functional cusps in ICP?
- Cusps that do not occlude with the opposing teeth in the intercuspal position
What cusps are non-functional cusps?
- Are buccal cusps of the upper posterior teeth and the lingual cusps of the lower posterior teeth
The functional cusps of a tooth contacts with what part of the opposing tooth?
The fossa
What cusps contact what fossas in the ICP?
- The lingual cusp of an upper molar contacts the fossa of a lower molar
- The buccal cusp of a lower molar contacts the fossa of an upper molar
What action would you ask the patient to perform if trying to use articulating paper to mark tooth contacts in the ICP?
Tap the teeth together
What malocclusions might you see in the static occlusion?
- Incisor relationships
- Class I
- Class II div 1
- Class II div 2
- Class III
- Overbite
- Overjet
- Posterior/anterior crossbites
- Anterior/posterio open bites
How big is an overbite normally?
2-4mm
Describe canine guidance.
- When the mandible moves to the left (working side) there is only contact between the canines
- There are NO posterior contacts (open space)
Canine guidance gives what kind of occlusion?
A mutually protected occlusion (the gold standard)
Why is mutually protected occlusion (canine guidance) preferable?
- The roots on the canines are adapted for these types of movements
- But the roots on molars aren’t developed for this so don’t want them experiencing lateral movements/forces
Where is bilateral group function more commonly seen?
toothwear cases and is more common as patients age
Describe the the occlusion/tooth contacts during protrusion.
(The condyle moves forwards and downwards on articular eminence)
- Only incisors +/- canines touch
- No posterior tooth contacts
What is an occlusal interference?
undesirable tooth contacts that may produce mandibular deviation during closure to ICP or may hinder smooth passage to and from ICP
Note: . As soon as we deviate from canine guidance, we end up with these
What different occlusal interferences do you get?
- Working side
- Non-working side
- Protrusive
Describe a working side contact occlusal interference.
Will have the canine and a posterior tooth on the working side contacting
(if moving jaw to left the LHS is the working side)
Similar cusps contact
What is a non-working side contact?
Undesireable contact during lateral movement on non-working side
Dissimilar cusps contact
What is protrusive interference?
This is any posterior contact during protrusion.
Why do we want to avoid posterior contacts?
- Teeth are designed to absorb heavy forces in the direction of the long axis of the tooth
- Won’t like it when lateral forces are applied
- Most teeth are not designed to absorb significant lateral forces…………generated by occlusal interferences
- Musculature gets a rest as less activity if not undesirable posterior contacts
- If teeth were constantly contacting then it will cause muscle problems – tiredness etc.
- Occlusal trauma and undesirable tooth movements
What pathology regarding occlusion may be present?
- bruxism
- tooth wear
- occlusal trauma
What are the 2 types of bruxism you get?
- essentric
- centric
What is essentric bruxism?
- The parafunctional grinding of teeth
- An oral habit consisting of involuntary rhythmic or spasmodic or functional gnashing, grinding or clenching of teeth in other than chewing movements of the mandible which may lead to occlusal trauma
- Side to side movement
What is centric bruxism?
- Clenching
- The pressing and clamping of the jaws and teeth together
- Frequently associated with acute nervous tension or physical effort
What are some clinical signs and symptoms of bruxism?
- Toothwear
- Fractured restorations
- Tooth migration
- Tooth mobility (Often in absence of periodontal disease)
- Muscle pain and fatigue
- Headache
- Earache
- Pain and stiffness in the TMJ and surrounding muscles
What might tooth wear be due to?
- Multifactorial (normally this)
- Abrasion
- Attrition
- Erosion
- Abfraction
How is tooth wear classed?
mild/moderate/severe
What is occlusal trauma?
Occlusal trauma is an injury resulting in tissue changes within the attachment apparatus, including periodontal ligament, supporting alveolar bone and cementum, as a result of occlusal force(s).
What are the diff ways that occlusal trauma can be classed?
- Primary
- intact periodontium
- Secondary
- reduced periodontium
- Fremitus
- palpable or visible movement of a tooth when subjected to occlusal forces
What is the checklist you should go through when examining occlusion?
- Incisor relationship
- Guidance
- Overjet/overbite
- ICP contacts
- Working/non-working/protrusive contacts (in dynamic occlusion)
- Pathology
