Week 2- Occlusion Flashcards
What are the 3 rules to follow with occlusion?
- To have bilateral and even occlusal contact.
- The disclusion of posterior teeth during canine guidance
- An unobstructed envelope of function.
What happens when a tooth interferes with full closure?
- Trigger deflective interferences
- Hypersensitivity
- Abfractions
- Mobility
- Excessive wear or fractures,
- Muscle/TMJ pain.
What can posterior teeth deflections create?
May create occlusal avoidance pattern leading to excessive anterior tooth wear
What does anterior and canine guidance allow for?
Immediate disclusion of molars and premolars when making lateral or protrusive movements. In doing so, masticatory muscles significantly decrease activity and there is decreased force applied to anterior teeth.
How does muscle function differ between when posterior teeth touch vs anterior teeth touch?
- When posterior teeth touch, the muscles can function with full force.
- When only anterior teeth touch, the forces decrease significantly.
What happens if a patients posterior teeth don’t disclude during lateral movements?
Posterior teeth grind over each other with full muscular force. It is typical to see these patients with severe signs and symptoms of occlusal disease.
What is meant by an unobstructed envelope of function?
Freedom of movement during chewing that swings md forward (protrusively) during the closure movement, returning back into the centric stop.
The correct amount of overjet allows the space for this protrusive movement to occur without interference.
What are some interferences to the anterior path of closure?
- Insufficient overjet
- Lingual morphology of the anterior teeth not concave enough
What movements are involved in Posselt’s envelope of motion?
- RCP
- Intercuspal Contact position
- Protrusive
- Rotational
- Translational
What is the working side and non-working side?
Working side: same side as you slide
Non-working: side not being engaged
What is canine guidance?
When you slide your teeth to one side and your canine is the only one that guides your teeth.
What is group function?
Contacting more than one tooth when you move your jaw in a sideways motion
What will you likely see in patients with group function?
Abfraction, cracks, fractures
Excessive wear on anteriors
Why is anterior guidance favourable to group function?
The constant pressure is taken off the posterior teeth, allowing for a more balanced distribution of the force over all our teeth.
What happens to posterior teeth if patient has anterior open bite?
Posterior teeth with grind against each other
If patient has violation of envelope of function, how can you stop it getting worse?
Occlusal splint
What is centric occlusion also known as?
Habitual bite
Bite of convenience
What is centric relation?
Relationship of md to mx when the articular disc is in place and the head of the condyle is in its most superior part of the distal facing incline of the glenoid fossa.
What is VDO?
Vertical dimension when teeth/substitute materials are in contact in the RCP.
What is curve of spee?
When you run line through middle of condyle and occlusal surface of teeth
What is a clue to a potential steep curve of spee?
Excessive wear on the occlusal surfaces of molars.
Where does curve of Wilson have significance?
In the smooth lateral translation of the condyle
What is the greatest problem associated with excessive overbite?
Trauma to gingival tissues on palate
Why is it difficult/impossible for patients with overbites to wear mx occlusal splints or partial dentures?
No room for thickness of acrylic without opening posterior occlusion
Which bite disorder is the most detrimental to the teeth and TMJ?
Deep overbite
What issues can be associated with malocclusion?
- Damage to teeth and gums
- Headaches
- TMJ disorder
- Hearing difficulties and digestive problems
What is occlusion?
Itntegrated action of the jaw muscles, TMJ, and teeth.
Interpret the following OPG
- Condylar remodelling
- Interference with opposing 17 on 47 causing thickening of PDL space
- Bridge abutment dislodged
- Incisal wear
Why does gonial notching occur?
Masseter muscle inserts in this area. When clenching teeth, it is pulled up.
Interpret the following OPG
- Gonial notching
- 12-23 incisal wear
- Condylar head remodelling
How are anterior guidance and condyles related?
When you go onto protrusion, and you start to get wear of the anterior teeth, the condyle starts to remodel.
What is a starting point for evaluating occlusion?
Intraoral evaluation of CR contacts
Diagnostic casts (mount in CR)
Compare CR and MI
What is the benefit of duplicated casts coated with project paint?
Paint allows easy visualisation of the areas that have not been reduced.
We can use articulating paper in the pts mouth to see contacts in CR and compare intraoral marks with the stone cast adjustments. Can then adjust the mouth in a manner similar to the stone casts. After adjustment, CR should equal MI.
Who are occlusal splints recommended for?
People with bruxism.
What are characteristics of a good splint?
- Flat
- Contacting all teeth
- Not too thin, bulky or tight
What tray do we use for mx vs md impressions for splint?
- Mx: metal tray
- Md: disposable plastic tray
What is the issue with NTI splints?
- Can get overeruption of posterior teeth
- Anterior open bite
- Sore anterior teeth
What is normal interarch space?
Interarch space should be 16-20mm but in atrophic mandible it is greater (dentures will be larger and heavier)
How should patient with angular cheilitis be managed?
- Remake dentures with increased vertical dimension.
- As temporary measure, prescribe Kenalog with Orabase (corticosteroid)
What can an excessively increased VDO lead to?
- Onset of joint and muscle pain
- Tension in functional speech
- Difficulty swallowing
- Impaired chewing
- Pathologic bone resorption
- Abnormal wearing of teeth
- Appearance of elongated face
- Facial expression fatigue
What are fovea palatini and their relevance to mx dentures?
2 indentations on each side of midline, formed by coalescence of several mucous gland ducts. They aid in locating the vibrating line and posterior border of denture.
When is surgical correction required for palatal tori?
If tori are very large and extend to the vibrating line.
What is zygomatic process?
Located opposite to the first molar region. Sometimes denture require relief in this area.
When should a lower splint be used rather than an upper?
If pt has 100% overbite, place lower splint rather than upper splint.
What is the typical thinning of teeth due to?
Violation of envelope of function
What is a common pattern seen when there is violation of envelope of function?
Severe “thinning” of incisal edges, or wear of the palatal surface of the maxillary anterior teeth with wear of the facial of mandibular anterior teeth.
What is this caused by?
Violation of envelope of function (ceramic crown wearing opposing teeth)
