Occlusion: teeth selection and type of occlusal schemes Flashcards
In edentulous pt, how to you decide ideal face height (OVD)?
RECORD REST FACE HEIGHT
measure lower third
dduct 2-3 mm from face height = OVD
What do you use to measure face height for OVD?
willis guage
bottom bar press onto bone not just soft tissue
what is the only fixed position for a n edentulous pt?
rest face height
3 points on a willis gauge?
the position of the fixed arm under the nose
the position of the sliding arm under the chin
the vertical orientation of the gauge
free way space?
you want this
difference between teeth at rest and in RCP (closed)
how to record bite?
record blocks
record rims should be placed in well-fitting rigid bases
- heat cured acrylic bases –> permanent denture base
- cold-curing acrylic resin
- shellac (cold cured)
try in mandibular or maxillary first?
maxillary
what happens if the wax try-in the denture is unretentive?
pt might do altered movements to try keep it in place
can you just add on to the flanges to extend them?
no - need new impression
where can you add or remove wax from?
lip support
incisal level
incisal tooth position
buccal
palatal surfaces
(latter changes to arch width)
Can you remove wax to change occlusal plane orientation?
yes on upper block
fox’s plane guide - should be parallel to ala-tragus line
when you are happy with the maxillary wax block, what do you do?
mark:
either side of nose
smile line
filtrum - midline
What do you adjust the lower block in relation to?
upper block
what to think about when trimming the lower wax block?
lip support, buccal and lingual surfaces
care with position of occlusal surfaces in relation to tongue
correct OVD - 2-4 mm between biting and rest position
how much free way space is needed?
2-4 mm
how to record the jaw relationship after both bite blocks are fitting well?
cut 2 notches is posterior occlusal surface of upper block –> one on each side
place upper record block in opts mouth
apply appropriate adhesive to lower block for bite recording paste being used
apply sufficient bite recording paste to occlusal surfaces of lower block - NOT ONTO ANTERIORS
insert block and guide pt into correct jaw relationship
allow sufficient time for material to set before removing from mouth - NOT A SNAP SET - hold for around 30 seconds
remove blocks carefully - may be sealed together
separate blocks carefully so that dental technician can cast impressions in upper and lower blocks where required
select appropriate anterior and posterior teeth
prescribe for correct articulator
how to know the bite blocks are fitting well?
pt needs to be in supine position
check relationship with blocks in pts mouth
ensure that is is as reproducible as possible
record ligamentous (or retruded contact position) if pt has moved to habitual path of closure
ligamentous position is considered the most reproducible
recheck that there is an identified FWS
ensure centre line is appropriate and marked if removed during modifications
what is the shade guide used?
DELPHIC V or VITA
what type of occlusal schemes are we going to prescribe? (most common)
most common: conventional bilateral balanced occlusion :
- inter-cuspal position = retruded contact position
- ICP on posterior teeth
- working side and balancing side contacts in lateral excursions
- anterior and posterior contact in protrusive excursions
why do we have the conventional bilateral balanced occlusion scheme?
mutually protecting
- denture will not be displaced if something is eaten on one side
contacts when pt has lateral and protrusive movement
What is lingualized bilaterally balanced occlusion?
- maxillary palatal cusps contacting mandibular central fossae
- different from conventional bilateral balanced occlusion by eliminating the contact between the mandibular buccal cusps and maxillary central fossae
How to achieve lingualized bilaterally balanced occlusion?
1 - modify anatomical mandibular posterior teeth or
2 - by applying anatomical maxillary posterior teeth against flat mandibular posterior teeth
What is the monoplane occlusion occlusal scheme?
can be establish balanced or nonbalanced occlusion
occlusal contact comprise surfaces rather than points
3 types of occlusal scheme you can prescribe?
conventional bilateral balanced occlusion
lingualized bilaterally balanced occlusion
monoplane occlusion occlusal scheme
when to prescribe LBBO?
severely resorbed ridge on mandibular arch
ALLOWS - masticatory efficiency and preservation of ICP)
factors influencing teeth selection?
previous dentures (if any)
age of pt
size and shape of facial skeleton
colour of complexion
pt choice
pt friend
OK or Hello magazine
old photos - usually school or wedding
materials of teeth?
acrylic
composite
porcelain
combination
acrylic teeth pros and cons?
highly cross-linked acrylic (improves wear resistance and colour stability)
good appearance and adhesion to denture base
wears quickly
composite teeth pros and cons?
harder and longer lasting than acrylic
good aesthetic properties
reduced bond strength to underlying acrylic
can be modified/added
porcelain teeth pros and cons?
retention to denture base through mechanical features celled diatoric holes (pins) designed into teeth (can be dislodged)
good appearance but can be noisy, chip with high occlusal forces, extra weight
How to decide central incisor width?
using philtrum width
the height of the central incisor should be equal to or greater than the height if the smile line above the incisal edge
high smile should be marked on the wax rim
when to use larger central incisor?
high lip line
larger stature
larger face
how to find canine position?
using a straight edge aligned with the inner canthus of the eye and the ala of the nose to find the position of the canine
how to select teeth shape?
using pt old denture
inverted shape of pts shape
shape of pt upper plate
4 types of teeth shape? `
square : complement square set face and strong features
ovoid : create sifter appearance and complement delicate, rounded features
tapering : tapering face
rectangular : long square shaped faces
How does position of teeth change with age and how would you consider this in denture design?
attrition of natural teeth:
incisal edge will tend to be flattened
loss of muscular toe of lips and face:
flanges and teeth need to attempt to restore ‘appearance’ (can be difficult)
need to place anterior teeth in correct position:
lip support but if too far anterior –> denture displacement
amount of tooth showing :
at rest and when smiling
positioning of posterior teeth?
3 compensating curves when positioning teeth?
anterior posterior- curve of spee
laterally- curve of monson
mediolaterl curve- curve of wilson
anterior posterior curve?
curve of spee
lateral curve?
curve of monson
mediolateral curve?
curve of wilson
