9B. Occlusal Trauma Flashcards
Masseter
• the musculature is right over the ____ teeth
• If you’re squeezing back and have one of those
interferences
◦Just image how much pressure is squeezing on that
tooth
‣ It can cause the tooth to become mobile, sore, you
can get TMJ issues.
posterior
Class 3 lever
• ____ interference is an example of a class 3 lever
◦If the fulcrum is the tmj and the effort is the muscles
◦You can generate ____ pounds of pressure on the molars
◦But on the front teeth, because it’s a longer lever arm, you are only generating ____ pounds of pressure
• *Note I didn’t understand what he was saying here *
◦“This is why the anterior teeth you can slide forwards and ____ the back teeth but it doesn’t damage the front teeth
◦If you did that in the back teeth with all the pressure it’s more damaging
nonworking
250
50
disarticulate
Bruxism Causes
- ____
- malocclusion
- ____ interferences
- ____ disturbance
- emotional stress
- ____ dentition
- psychotropic medications
idiopathic
occlusal
neuromuscular
transitional
Psychotropic Medications Implicated with Bruxism
- Selective serotonin reuptake inhibitors
- Antipsychotics
- Antidepressants
\_\_\_\_ (venlafaxine) Haldol (haloperodol) \_\_\_\_ (fluvoxamine) Prozac (fluoxitine) \_\_\_\_ (sertraline)
effexor
luvox
zoloft
Bite collapse
• bite collapse occurs when one of the basic rules of occlusion has been violated.
◦Mainly the posterior teeth support the occlusion and the anterior teeth disarticulate
◦If there is no ____ teeth and you bite down (next slide)
posterior
Bite collapse
- whether its missing teeth, broken down teeth, or decayed teeth the trauma isn’t here (points to red arrow), its here (points to orange arrow)
- As the jaw over closes the ____ teeth can’t take that much pressure and they start to flair out
- So a bite collapse can cause this trauma to the ____ teeth
anterior
anterior
Bite collapse
• Just restoring that normal marginal ridge anatomy will restore the bite 2-3 mm will kinda give you an idea of how much that bite has collapsed
• To treat this pt properly you would have to restore some kinda ____ support — ideally implants, as well as restore the VDO that was lost by the bite collapse
• Then once you restored that, the anterior teeth may return to a normal position just from ____ alone
◦ But sometimes we’ll use ____ to pull the teeth back in, so they can provide anterior guidance once we have posterior support
posterior
lip pressure
ortho
Bite collapse
• even in a minor bite collapse, like this, there can still be trauma because the teeth are hitting off axis
◦The teeth aren’t being supported the way the oblique fibers of the PDL best support it
• This tooth is being hit off axis every time the pt bites down — its being crushed
• If a pt loses a molar and doesn’t replace it. The tooth behind it moves forward and you often see a pocket right here
• The reasons for this pocket are:
◦You get a little valley that is hard to clean so ____ and
plaque is getting trapped
◦Also the ____ is getting crushed every time the pt
bites down
‣ Its a ____ of destruction
• So look for these ____ where ever you see collapsed teeth, such as this.
food
ligament
cofactors
pockets
Premature contacts and interferences
Early contacts occurring in jaw movement that are stronger or sooner than desired \_\_\_\_ (Fremitus) \_\_\_\_ \_\_\_\_ \_\_\_\_
centric
protrusive
working
non-working
Cusp to fossa
- These two pictures were taken the same day
- As he reduced the ____ the teeth just settled together
- Over the next few weeks the mobility subsided on this tooth
contour
Protrusive interference
• So what’s happening here?
◦You should be able to look at a case like this and say this is a
bruxer
◦The pt was referred to him because of right side myofascial pain and he had tenderness in the muscles.
‣ So it wasn’t a joint problem it was a muscle problem
• What’s causing this?
◦It’s not the bruxism, although that’s part of it
◦What’s happening here (points to red arrow) is the pt was
having a protrusive interference.
◦He had his upper third molar (#16) removed, but not #17 so it
super erupted
◦Now he is trying to grind on his front teeth, but he cant bc the
third molar is ____ with the second molar in the upper
quadrant
◦This is causing the muscles to go into ____
• The treatment of this is to ____ the lower left third molar and a ____ to control the bruxing habbit
interfering
spasm
extract
bite guard
Working interference
• lets look at working interferences
• this patient came to him bc she had a crown placed on #14 that became sore and mobile
◦The referring dentist check the bite and said it wasn’t high, so
he didn’t know what was wrong
◦BUT he didn’t check the tooth as it went into ____ excursion
‣ There was an interference
‣ The buccal cusp on #14 was too long and the K9 no longer
had contact
‣ Is the buccal cusp a support or guiding cusp? (No one
answers)
• What are the supporting cusps?
◦The ____ of the upper and buccal of the lower
• So the buccal of #14 is a ____ — it doesn’t
support the bite, so we can shave that cusp and not change the support for the bite
lateral
palatal
guiding cusp
Working interference
• so we shaved the guiding cusp and we now have contact in the ____ area
◦You don’t want the contact back here (points to the arrow in the posterior)
• Remember the cusps in the fossa are the ____
K9
supporting cusp
Working side interference cross tooth
• This is another working interference, but its not the buccal of the upper its the lingual of the lower
◦So the pt is sliding to the right, this shouldn’t be hitting as the patient goes into this movement
‣ This fossa is too ____
‣ This is a working interference
deep
• this patient has two crowns. What is wrong with these crowns?
◦Student response: “they look large relative to the other teeth”
• What else is wrong? Which cusp should be higher on the lower teeth the buccal or the lingual? (Next slide)
• (comes back to this slide) These are too high
‣ Why are they too high — its the way the lab made them
• Don’t assume the lab knows more about occlusion than you do.
‣ What the lab did was match it to the broken down tooth adjacent to the crowns
READ ME
Curve of wilson (transverse curve)
Curve represented by the cusp tips of molars in the ____ plane
• Think about basic occlusion — the curve of Wilson/ the transverse curve.
◦The ____ cusp of the upper hang down lower than the ____ cusp to give you the normal curve of Wilson
◦goes back to previous slide
frontal plane
palatal
buccal
• Now the pt is moving to the right side.
• The interference is removed and there is guidance on the
____
• these guiding cusp - someone used the rule of ____, the
buccal of the upper, the lingual of the lower
◦This is an easy way to remember which cusps are the
guiding cusps
◦Unless its a cross bite, you should be able to reduce
the guiding cusps without changing the basic support of the bite
‣ If you reduce the supporting cusp too much, you can close the bite and the ____ teeth will start to hit
• Causing these teeth to become loose or separate
canine
bull
anterior
Non-working interference
Prematurture contact on the ____ side preventing guidance on the working side
• non-working interferences are the tough ones
• These occur on the ____ cusps
◦The palatal of the upper and the buccal of the lower
non-working
supporting
Non-working interference
• this pt is moving their jaw to the left
• This is a non working interference — it usually happens in the ____ areas
• This pt has very ____ cusps — that’s what’s interfering
• You can’t just arbitrarily reduce the supporting cusps as I
said before
◦You might end up having the front teeth coming
together too ____
molar
steep
hard
• we have the pt slide to the side to observe the non working interference
◦But this isn’t where the damage occurs
• The damage occurs on the return stroke as the pt
squeezes the teeth together
• As the jaw slides out to the side you are using relatively
____ muscles ( Lat. pterygoid, geniohyoid, digastric)
• The ____ muscles (masseter, temporalis, medial
pterygoid) occur on the return stroke.
weak
strong
Non-Working Interferences Problems
• A major cause of ____ trauma
• Mechanical threat to ____ cusps
• Problem area confuses patient. Chewing on ____ side makes it worse
• ____ makes the problem worse as contacting areas widen
• Occlusal irritant associated with ____
occlusal supporting opposite wear MFP
Non-working interferences
- Usually located on the ____ incline of the lower supporting cusps and ____ incline of the upper supporting cusps.
- Also ____ cusps of upper molars and ____ cusps of lower molars.
- Runs ____ across tooth
- Any alteration in plane of occlusion, increase in cusp height, or transverse curve ____ its potential
- Results from interplay between working,side, nonworking side and condylar elements
mesial inner distal inner mesiolingual disto-buccal diagonally increases
Causes of non-working interferences
First look at the ____ side –is there guidance?
Loss of tooth substance on FOA or guiding incline due to: ____ teeth Caries fracture Wear
Drifting teeth as in ____ bite collapse
____ Deformity
working
missing
posterior
orthodontic
Causes of non-working interferences on working side
• If there is no ____ here, something is going to hit back here
guidance
Orthodontically incorrect relationships
• This is an adult who had crowded ____ incisors - just wanted bottom teeth straightened
◦“You cant but a quart in a pint bottle”
◦If you spread these teeth out you are going to loose ____,
which is what happened here.
• So orthodontic errors can cause loss of guidance
lower
guidance
Causes of Non-Working Interferences On the
NON- Working Side
• Tooth loss-____
tilting and extrusion
Shifting and Interferences Caused by Overcarved Restorations
• Dentist can cause interferences by ____ restorations
• If its too deep the cusps will ____ in together
◦There is no freedom for the patient to move side to side leading to trauma of the tooth
over carving
lock
