Occlusion Flashcards
Chewing is what type of lever?
Class 3, where effort (muscles) is between the fulcrum (TMJ) and the load (teeth/food)
Each maxillary tooth occludes with ___.
Counterpart and the tooth immediately distal to it
Each mandibular tooth occludes with ___.
Counterpart and tooth immediately mesial to it
Which mandibular tooth occludes with only one other tooth?
Mandibular central incisor
Which maxillary tooth occludes with only one other tooth?
Maxillary third molar
Every maxillary tooth is more ___ than its opposing counterpart.
Distal
Axial loading of posterior teeth
Occlusal forces are applied along long axis of tooth
Cusp tip contact with fossa / MR
Posterior teeth contact simultaneously. T/F
True
What contacts are seen in protrusive jaw movements (protrusive excursion)?
Anterior contact, no posterior contact
What contacts are seen in lateral excursive jaw movements?
Working side contact, no contact on non-working side
Centric occlusion (CO)
Jaw position that is determined by the position of the teeth
Has maximum intercuspal position (maximum interdigitation) of the teeth
Cusps of teeth interpose themselves with cusps of opposing arch
Reciprocal incline contact
Contact with opposing tooth is on the side of the cusp (not the tip) in posterior teeth
Tripod occlusion (groups of 3)
Which teeth participate in axial loading?
Posterior teeth
Anterior teeth have lighter contact, not conducive to axial loading
What are alternative names for working cusps?
Functional, supporting, centric
What are the functional cusps of maxillary teeth?
Lingual cusps
What are the supporting cusps of mandibular cusps?
Buccal cusps
What are alternative names for non-working cusps?
Guiding, noncentric
What are the guiding cusps for maxillary teeth?
Buccal cusps
What are the noncentric cusps of mandibular teeth?
Lingual cusps
Which cusps of maxillary teeth would be blunt and rounded?
Lingual cusps
Which cusps of mandibular teeth would be sharp?
Lingual cusps
The lingual cusp line extends through the lingual cusp tips of ___ teeth.
Maxillary posterior
The buccal cusp line extends through the buccal cusp tips of
Mandibular posterior
Deep bite / overbite
Maxillary anterior teeth have extreme overlap to mandibular teeth
Can cause decreased vertical facial height
Strong anterior guidance (mandibular incisors touch lingual side of maxillary incisors quickly in protrusion and slide down entire length of lingual surfaces, causing rapid disclusion)
Can cause palatal damage if severe
What are the key characteristics of overbite / deep bite?
- -Maxillary anterior overlap
- -Strong anterior guidance
- -decreased vertical facial height
- -rapid disclusion with protrusion
The lack of anterior guidance during protrusion is characteristic of overbite. T/F
False, strong anterior guidance is seen in overbite, a lack of anterior guidance is seen in open bite
Open bite characteristics
- -Lack of anterior guidance during protrusion
- -Anterior teeth don’t touch
- -Face appears longer (increased vertical facial height)
Decreased facial height can be seen with ___ while a longer face can be seen in ___.
Overbite, open bite
Crossbite characteristics
- -Mandibular buccal cusps are buccal to maxillary buccal cusps
- -Unilateral or bilateral
- -Can be corrected
Overjet
- -Protrusion of teeth
- -Increased horizontal distance between lingual surface of maxillary incisors and facial surface of mandibular incisors
- -Increased horizontal overlap forces a decrease in posterior cusp length
How does overjet and overbite differ?
Overbite has increased vertical overlap of maxillary and mandibular incisors
Overjet is increased horizontal distance between maxillary and mandibular incisors
Where do maxillary premolars contact occlusally?
Lingual cusp contact the distal fossa of antagonist
Where do maxillary molars contact occlusally?
The mesiolingual cusp contacts the central fossa of antagonist
The distolingual cusp contacts the distal MR of antagonist and mesial MR of distal tooth
Where do mandibular premolars contact occlusally?
The buccal cusp contacts the mesial MR of antagonist
Where do mandibular molars contact occlusally?
The mesiobuccal cusp contacts the mesial MR of antagonist and the distal MR of mesial tooth
The distobuccal cusp contacts the central fossa of antagonist
Bruxing
Grinding of teeth
Accompanied by clenching of jaw
Can occur during sleep
Causes problems in ear, jaw, neck, throat, mouth, teeth, eyes, headache, abfraction (non-carious tooth loss near gingiva)
What is the key sign of bruxing?
When you see teeth out of position
Working side
The side that the mandible moves towards in lateral excursion (laterotrusive)
Non-working side
The side that moves towards the midline (mediotrisve, balancing)
No occlusion on non-working side
___ is moving the mandible forward in an anterior-posterior plane.
Protrusion
___ is moving the mandible backwards in an anterior-posterior plane.
Retrusion
Which movement is an almost straight lateral movement?
Working movement
Which movement is a more diagonal movement?
Non-working movement
medial, anterior, down
Excursive mandibular movements cause increased axial loading. T/F
False, they result in lateral loads on teeth
In a protrusive movement, which teeth contact?
Anterior teeth contact for guidance
Posterior teeth separate / disocclude
Anterior guidance
Incisors and canines guide the mandible in protrusion and lateral excursion, make up anterior determinant of mandibular movement
Controlled by dentists through: restoration, equilibration, or orthodontics
Also determined by TMJ and neuromuscular system (not controlled)
How does overjet and overbite affect posterior teeth?
Overjet causes posterior cusps to be shorter, while overbite allows posterior cusps to be longer
What are the guiding cusps?
Maxillary buccal and mandibular lingual
What are the function of the guiding cusps?
Guide the supporting cusps out of occlusion in contact movements
Protect the cheek and tongue from being bitten
What is considered the ideal guidance in working side contacts?
Canine guidance by lingual surface of maxillary canine
Canine guidance
In lateral excursion, the lingual surface of the maxillary canine takes on lateral load
–Ideal guidance
Group function
In lateral excursion, the buccal cusps of maxillary posterior teeth take on lateral load
–Occurs when no canine guidance is seen (position/length of canine is irregular)
What is an alternative to canine guidance in lateral excursion?
Group function
4 characteristics of supporting cusps
- -Broader, more rounded
- -Contact opposing tooth in maximum intercuspal position
- -Support vertical dimension of face
- -Contact near buccolingual center of opposing tooth
The oblique ridge of the maxillary first molar opposed what structure?
Distobuccal groove of mandibular first molars
The mesiobuccal cusp of the maxillary first molar passes through what structure?
Mesiobuccal groove of the mandibular first molar
What is mutually protected occlusion?
In occlusion, the intercuspal position of posterior teeth protect the anterior teeth from excessive contact
Also, the anterior teeth protect the posterior teeth by disengaging the posterior teeth in excursive movements
In normal occlusion, the working side has slightly more contact than the nonworking side. T/F
False, the nonworking side has no contact
Destructive movements occur in ___ side contacts of the ___ cusps.
Nonworking (mediotrusive movements)
supporting
The #13 lingual cusp broke. What movement caused it and with what tooth did it contact?
Lingual cusp of left maxillary second premolar is supporting
Left nonworking movement (mediotrusive)
Contacted buccal cusp of #20 (left mandibular 2nd premolar)
Destructive movement is a ___ movement.
Non-working movement (mediotrusive)
The #29 buccal cusp broke. What movement caused it and with what tooth did it contact?
Buccal cusp of right mandibular second premolar is supporting
Right non-working movement (mediotrusive)
Contacted lingual cusp of #4 (right mandibular second premolar)
Centric relation
The mandibular jaw position where head of condyle is situated as far superior and anterior as possible in the mandibular fossa
In centric relation, the head of the condyle is situated ___ and ___ in the ___.
Superior, anterior, mandibular fossa
Bennett movement
Lateral excursion (shift) of mandible, due to movement of condyles in the mandibular fossa
Working side movement is almost straight lateral movement of condyle on same side that mandible is moving towards
Balancing side movement is diagonal movement of condyle on opposite side that mandible is moving towards
In a Bennett movement, the balancing side movement is ___.
Diagonal
