RPD LAB - SETTING TEETH IN RPD

Question 1

what is the aim when setting artificial teeth for partial dentures

Answer 1

to have the teeth set in a position that will complement the existing teeth, thus restoring the arch, aesthetics and function

Question 2

if the aim of setting the teeth for RPD is accomplished what will be the result?

Answer 2

it will greatly improve patient self-confidence and protect their ‘denture privacy’

Question 3

is there any difference when setting teeth for a cobalt chromium base or a PMMA base

Answer 3

no

Question 4

what must be considered for cobalt chromium bases

Answer 4

the scheme for mechanical retention for PMMA to metal base

Question 5

what are the possible schemes for mechanical retention for the cobalt chromium bases

Answer 5

post or mesh depending on the available space

Question 6

describe the properties of the plastic/acrylic teeth

Answer 6

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

Question 7

what are the advantages of porcelain

Answer 7

natural appearance
hard-high resistance to abrasion
inert in mouth so no dimensional change
no permanent deformation under the forces of mastication

Question 8

what are the disadvantages of porcelain

Answer 8

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

Question 9

what information does the tooth mould chart provide

Answer 9

shape of the tooth
length of the anterior teeth
height of central incisor
width of central incisor

Question 10

how is acrylic held in the denture base

Answer 10

chemical bond with the denture base

Question 11

how are porcelain teeth held in the denture base

Answer 11

mechanical bond

Question 12

how is the mechanical bond created in the porcelain teeth in anterior teeth

Answer 12

provided by a metal retention pin incorporated within the tooth of anterior teeth

Question 13

how is the mechanical bond created in the porcelain teeth in posterior teeth

Answer 13

have a hollowed area that will fill with the denture base

Question 14

what can compromise the setting of teeth

Answer 14

the edentulous space, may not be able to fit the amount of teeth required and make it symmetrical

Question 15

what do you use to choose teeth

Answer 15

mould charts

Question 16

what are the categories seen on a mould chart

Answer 16

shape
length of anterior teeth
height of central incisor
width of central incisor

Question 17

what are the subcategories of shapes of teeth

Answer 17

square
ovoid
tapered

Question 18

why do you not want high cusps

Answer 18

leads to an unstable denture

Question 19

when adjusting the tooth mould where should you NOT trim from and why

Answer 19

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

Question 20

where should you remove from when adjusting the tooth

Answer 20

the ridge lap

Question 21

what can happen if you reduce the ridge lap a lot

Answer 21

there is less bonding area available

it can therefore affect he bond with the ‘enamel’ layer having a harder surface

Question 22

how can you try to prevent the tooth debonding

Answer 22

trim teeth with diamond cutters

use a post for retention when space is limited

Question 23

what should you ensure to prevent tooth debonding in heat cure

Answer 23

no wax or grease on teeth surface

no mould seal present when processing

Question 24

what should you ensure for self cure to prevent debonding

Answer 24

try to avoid heavy contact on denture teeth
no wax or grease
no mould seal
add a drop of monomer onto before acrylic

Question 25

why should the occlusion be checked before setting teeth

Answer 25

the wear facets on the natural teeth should be checked as the artificial teeth must conform to the existing tooth surface wear

Question 26

What is the natural tooth guidance followed by

Answer 26

the artificial teeth

Question 27

how do you check for tooth guidance

Answer 27

using the canine teeth or groups of teeth such as the premolars

Question 28

why do the artificial teeth need to follow the natural guidance

Answer 28

so that the tooth glides over and there is not any premature contact that could break the teeth off

Question 29

why do you also need to look at lateral excursion

Answer 29

to ensure that the teeth won’t be compromised in anyway

Question 30

what is the denture base for the trial denture stage and occlusal rim stage

Answer 30

it is a temporary base that will be discarded at the processing stage of denture production

Question 31

what is the temporary denture base made up of

Answer 31

it is a rigid base with wax saddle

usually made of light cured acrylic or shellac

Question 32

how is symmetry provided

Answer 32

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

Question 33

where should final adjustment of tooth length be done

Answer 33

at chair side if the denture is not tooth supported

some movement might be expected