RPD LAB - SETTING TEETH IN RPD Flashcards
what is the aim when setting artificial teeth for partial dentures
to have the teeth set in a position that will complement the existing teeth, thus restoring the arch, aesthetics and function
if the aim of setting the teeth for RPD is accomplished what will be the result?
it will greatly improve patient self-confidence and protect their ‘denture privacy’
is there any difference when setting teeth for a cobalt chromium base or a PMMA base
no
what must be considered for cobalt chromium bases
the scheme for mechanical retention for PMMA to metal base
what are the possible schemes for mechanical retention for the cobalt chromium bases
post or mesh depending on the available space
describe the properties of the plastic/acrylic teeth
chemical bond with the denture base
natural appearance and feel-silent in function
tough
soft-low abrasion resistance
easily trimmed and polished/customised
cold flow under pressure
insoluble in mouth fluids but there is some dimensional change
what are the advantages of porcelain
natural appearance
hard-high resistance to abrasion
inert in mouth so no dimensional change
no permanent deformation under the forces of mastication
what are the disadvantages of porcelain
mechanical attachment with the denture base through silane coupling agent
noisy during function
friable - grinding removes surface glaze
can wear down opposing natural teeth
high heat distortion
what information does the tooth mould chart provide
shape of the tooth
length of the anterior teeth
height of central incisor
width of central incisor
how is acrylic held in the denture base
chemical bond with the denture base
how are porcelain teeth held in the denture base
mechanical bond
how is the mechanical bond created in the porcelain teeth in anterior teeth
provided by a metal retention pin incorporated within the tooth of anterior teeth
how is the mechanical bond created in the porcelain teeth in posterior teeth
have a hollowed area that will fill with the denture base
what can compromise the setting of teeth
the edentulous space, may not be able to fit the amount of teeth required and make it symmetrical
what do you use to choose teeth
mould charts
what are the categories seen on a mould chart
shape
length of anterior teeth
height of central incisor
width of central incisor
what are the subcategories of shapes of teeth
square
ovoid
tapered
why do you not want high cusps
leads to an unstable denture
when adjusting the tooth mould where should you NOT trim from and why
you shouldn’t remove from the length of the tooth (cervical margin or incisor tip) as it can affect the shade and also create an unnatural appearance
where should you remove from when adjusting the tooth
the ridge lap
what can happen if you reduce the ridge lap a lot
there is less bonding area available
it can therefore affect he bond with the ‘enamel’ layer having a harder surface
how can you try to prevent the tooth debonding
trim teeth with diamond cutters
use a post for retention when space is limited
what should you ensure to prevent tooth debonding in heat cure
no wax or grease on teeth surface
no mould seal present when processing
what should you ensure for self cure to prevent debonding
try to avoid heavy contact on denture teeth
no wax or grease
no mould seal
add a drop of monomer onto before acrylic
why should the occlusion be checked before setting teeth
the wear facets on the natural teeth should be checked as the artificial teeth must conform to the existing tooth surface wear
What is the natural tooth guidance followed by
the artificial teeth
how do you check for tooth guidance
using the canine teeth or groups of teeth such as the premolars
why do the artificial teeth need to follow the natural guidance
so that the tooth glides over and there is not any premature contact that could break the teeth off
why do you also need to look at lateral excursion
to ensure that the teeth won’t be compromised in anyway
what is the denture base for the trial denture stage and occlusal rim stage
it is a temporary base that will be discarded at the processing stage of denture production
what is the temporary denture base made up of
it is a rigid base with wax saddle
usually made of light cured acrylic or shellac
how is symmetry provided
setting the tooth to the long axis of the corresponding tooth - any angulation should be taken into account
contact points should also correspond to the natural dentition
where should final adjustment of tooth length be done
at chair side if the denture is not tooth supported
some movement might be expected
