4/17: Determinants of Occlusal Morphology II Flashcards
What do horizontal forces influence?
The direction of the ridges an grooves on the occlusal surfaces, and also the placement of the cusps
What does it mean that the mandible moves medially?
Right mediotrusion means that the right condyle moves medially (same as left lateral movement)
What is the non working pathway called?
Mediotrusive pathways
What does it mean that the mandible moves laterally?
Right laterotrusion means that the right condyle moves laterally (same as right lateral movement)
- right lateral, mediotrusion left
A: non-working pathway or mediotrusive pathway
What are the working pathways also called?
Laterotrusive pathways
What are horizontal factors?
- distance from the rotating condyle
- distance form the midsagital plane
- amount of mandibular lateral translation
- intercondylar width
Horizontal factors are the effect of distance of the tooth from the ________ and ___________
Rotating condyle; midsagittal plane
Horzontal movements are the effect of what three things?
- Effect of distance of the tooth from the
- rotating condyle
- midsagittal plane - Effect of mandibular lateral translation movement
- Effect of intercondylar distance
The greater the distance of the tooth from the rotating condyle, the _______ the angle formed by the working and non working pathways
Wider
- same in the mandible and maxilla
Most of the times teeth that are closer to the midsagittal plane will be at ___________ distance from the rotating condyle
Greater
What do teeth that are positioned more anteriorly in the jaw (premolars) tend to have?
Greater angles between mediotrusive and laterotrusive pathways compared to teeth that are positioned more posteriorly (i.e., molars)
What does the angle formed by the working and non working pathways increase?
The amount of lateral translation increases
- the direction of the lateral translation also influences the angle
- same in the mandible and maxilla
The angle formed by the working and non working pathways _________ as the intercondylar distance ___________
Decreases; increases
Describe composite movements in a cusp fossa relationship
What is another term for working interfering contact?
Laterotrusive contacts
What is another term for non working interfering contact?
Mediotrusive contacts
What are three components of the masticatory system?
Mastication
Swallowing
Speech
What is mastication?
Initial stage of digestion
What is control of the central pattern generator?
Rhythmic separation and closure of the teeth
- autonomic/involuntary- can be controlled voluntarily
What is the chewing stroke?
Single cycle of opening and closing
What shape is the chewing stroke?
Tear shaped pattern (frontal)
What are the phases of the chewing stroke?
Opening phase
Closing phase
- crushing phase
- grinding phase
Where does the chewing stroke begin and end?
At MIP
What creates more vertical chewing stroke?
Taller cusps
Depper fossae
Most people have a preferred ___________
Chewing stroke
What occurs during mastication?
Tooth contacts
What is increased as food is broken down?
Increased frequency of contacts
- gliding contact (cuspal inclines)
- single contacts (MIP contacts)
What is the average length of time of contact?
194 MSEC
How do forces vary in maximal biting forces?
Male > female
Skeletal relationships and occlusion
Race (eskimos)
Anterior or posterior tooth
mastication or swallowing
What is the average max biting force?
80 to 150lbs (greatest was 975 lbs)
When is forces least?
For chewing (36% of max biting)
What is the biting force of dentures?
1/4 that of natural teeth
What is the definition of swallowing?
Series of coordinated muscular contractions that move a bolus of food from th eoral cavity through the esophagus to the stomach
What kind of muscle activity is swallowing?
Voluntary/involuntary reflex
- somtaic/visceral swallow
During swallowing, what is the mandible stabilized by?
Tooth contacts (MIP)
How long is tooth contact during swallowing?
683 msec
Lower levels of muscle activity if _____ and ____ are coincident
MIP; CR
How many times per day do we swallow?
Up to 700 times
What is the first stage of swallowing?
- voluntary control
- bolus of food is created
- lips are sealed
- tip rests against hard palate behind incisors
- teeth contact in MIP
- reflex reaction in tongue pushes food posteriorly into pharynx
What is the second stage of swallowing?
- food bolus in pharynx
- contraction of pharyngeal constrictor muscles move food to esophagus (peristalsis)
- soft palate rises and seals off the nasal passages (nasopharynx)
- epiglottis seals off trachea
What is the velopharyngeal seal?
Soft palate rises and seals off the nasal passages (nasopharynx)
What is the third stage of swallowing?
- peristaltic waves move food into the stomach (6-7 seconds)
- cardiac sphincter relaxes and food enters stomach
What is speech?
Controlled contraction and relaxation of the vocal cords as air is moved through the larynx
When does speech occur?
During expiration
Do the teeth contact during speech?
NO
Since the teeth don’t contact during speech, what can help determine?
A patients correct occlusal vertical dimension
Where are the centric occlusion contacts?
Where are the canine guidance contacts?
Where are the group function contacts?
