Lecture 13- Determinants of Occlusal Morphology Part 2 Flashcards
what do horizontal factors influence
the direction of the ridges and grooves on the occlusal surfaces and the placement of the cusps
what happens in right mediotrusion
the right condyle moves medially
what happens in right laterotrusion
the right mandible moves laterally
what are the horizontal factors
-distance from the rotating condyle
-distance from the midsagittal plane
- amount of mandibular lateral translation
-intercondylar width
what do horizontal factors effect
-effect of distance of the tooth from the rotating condyle and the 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 the angle
the greater the distance of the tooth from the midsagittal plane the ____the angle formed by the working and non working pathways
wider
most of the time teeth that are closer to the midsagittal plane will be at ____ distance from the rotating condyle
greater
teeth that are positioned more anteriorly in the jaw tend to have greater _________ compared to teeth that are positioned more posteriorly
angles between mediotrusive and laterotrusive pathways
the angle formed by the working and non working pathways increases as the amount of ____
lateral translation increases
the direction of the lateral translation also influenes ____
the angle
what is the effect of intercondylar distancr
the angle formed by the working and non working pathways decreases as the intercondylar distance increases
what is another term for working interfering contacts
laterotrusive contacts
what is another term for non working interfering contacts
mediotrusive contacts
what makes up the physiology of the masticatory system
-mastication
-swallowing
- speech
describe mastication
- initial stage of digestion
- rhythmic separation and closure of the teeth- control of the central pattern generator
- automatic/involuntary- can be controlled voluntarily
what is the chewing stroke
single cycle of opening and closing
what is the shape of the chewing stroke and what makes up the phases
-tear shaped pattern
- opening phase
- closing phase: crushing phase and grinding phase
where does the chewing stroke begin and end
at MIP
what would tall cusps and deep fossae indicate about the chewing stroke
more vertical chewing stroke
most people have a _____ chewing stroke
preferred
____ frequency of contacts as food is broken down
increased
describe the tooth contacts during mastication
-gliding contact (cuspal inclines)
- single contacts (MIP contacts)
what is the average length of time of tooth contacts in the chewing stroke
194 msec
how do maximal biting forces vary
-male > female
- skeletal relationships and occlusion
-race (eskimos +++)
- anterior or posterior tooth
- mastication or swallowing
what is the average max biting force
80-150 lbs
are maximal biting forces stronger or chewing forces
maximal biting forces
what are the maximal biting forces of dentures
1/4 that of the natural teeth
what is the definition of swallowing
series of coordinated muscular contractions that move a bolus of food from the oral cavity through the esophagus to the stomach
describe the swallowing reflex
voluntary/involuntary and reflex muscle activity
- somatic/visceral swallow
what is the mandible stabilized by during swallowing
tooth contacts in MIP
how long is tooth contact during swallowing
683 msec
how is muscle activity affected during swallowing if MIP and CR are coincident
lower levels of muscle activity
how many times a day do we swallow
up to 700
describe what happens in 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
describe what happens in 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) = velopharyngeal seal
- epiglottis seals off trachea
what happens during the third stage of swallowing
-peristaltic waves move food into the stomach in 6-7 seconds
- cardiac sphincter relaxes and food enters stomach
what happens during speech
controlled contraction and relaxation of the vocal cords as air is moved through the larynx
when does speech occur
during expiration
do teeth touch during speech
no
what is speech used to determine in patients
correct OVD
