12. System Desain

8/12/2019 12. System Desain

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.

Retentio

n/gre

en1F

ig

.

!

Re

tenti

on

+t

is

pr

ac

tic

ab

le

to

obtain

clasp

retenti

on

from

onlythree

teeth

#R;#1;%2

R" #1"%and !"#$"%%.Thussupplementaryretentionmust be

obtainedby widepalatalcoverage2 fullextensio

n ofthedenturebaseintotheleft

buccalsulcusandarou

ndthelefttub

erosity2an

d bycontactwith theguidesurfaceswhichwill beprepared

on theabutment teeth.

/smostof the

undercutonR;#1;% is

situatedonitsme

siobuccal

aspec

t2 a9ring9

clasp

is a

suitable

desig

n. +t isnot

possi

ble to

use agingiv

allyappro

achin

g

clasp

onR"

#1"%

becau

se of

a

bony

under

cut in

the

buccal

sulcus. /s

an

occlusally

appro

achingclasp

is the

only

reasonab

lealter

nativ

e2

wrou

ghtgold

wire

has

been

chos

en

be

ca

us

e it

po

ss

es

ses

suf

fici

ent

fle

xibility forthe short

clasp arm to

functionefficiently.

/s aprominent

fraenum

precludes agingivally

approaching

clasp on

!" #$"%2 a

wrought gold

occlusally

approaching

clasp is to be

used here

also.

(racing

and

reciprocati

on /blue1

Fig. "

#racingand

reciprocati

on

+t has been

d9r

ofallretentivearms2thusproviding

cross&archreciprocation

.

*onnector/blac1andindirectretentionF

ig

.

$

C

o

n

n

e

c

t

o

r

a

n

di

nd

ir

e

ct

r

e

t

e

nti

o

n

=or

th

e

re

a

s

o

n

s

gi

v

en

al

re

a

d

y2

w

id

e

pa

lat

al

co

ve

ra

ge

by

th

e

co

nn

ec

tor

isneeded.-

owever2itispossibleto:eepthe

anteriorborderofthepalatalpl

ateawayfromtheanteriorteethand

fromthesensitiveareaaround theincisivepapilla topromotehygieneandtolerance totheframewor:.

+t isnecessarytoplanforindirect

retentiontopreventthedistal

extension

saddlefrommovingocclusally. Thema>orclaspaxis is

sitedthroughR;#1;% and!"#$"%.Themesialocclusalrest onR"#1"%

will betheindirect

retainerto resistthedisplacing force


5/8

.* R +T+ ,- DET/! 0 R /!2 3! 4E 1(52 . 112 D E6E4*ER 5 $777 '(;


6/8

prost heti cs

Design prescriptionFig% & esign prescription/ provisional R


7/8

4

Toothsu

pportfor

thesad

dlewi

llbegainedfr

omam

esialoccl

usal

reston!!"

#8"%.Thegr

eatestpossi

blemucosa

supportforthe

saddle

isac

hieved byextendingthe

denturebaseontothe

pear&shaped padand tothe

fu

thearchit

isimportant

tospreadth

esupport sothat astable

prost

hesis

canbeproduced2thus

restshavebeenplaced on

!R"#""%2!R)#")%and

!R(#"(%.Theocclusal

restson themolarsbridg

e thegapbetween thetwo

teeth.Restseatpreparation

sca

Ret

ent

ion

/gre

en1Fig.

11

R

ete

ntion

The

di

st

al

ex

te

ns

io

n

s

a

d

d

le will

be

caref

ully

shap

ed to

emu

allo

w

agi

ng

ivall

y

approachin

g

cl

a

sp

to beused

on

!!"#8"%.

This

claspwill

be

oneof the

comp

onents

for

theR


8/8

.*R+ T+ ,- D ET/ ! 0 R /!2 3! 4E 1( 52 . 112 DE6E4 *ER 5 $777 '(5

Pp

Design prescriptionFig. 1" esign prescriptionThe design is reviewed as described in =ig. ) and then given to thedental technician on a clearly labelled proforma as described forExample 1.+n this instance the whole casting will be constructed in cobaltchro mi u m all o y

.Fig. 1$ esign prescriptionThe shape of the lingual sulcus2 faithfully recorded on the cast2dictates the shape and location of the sublingual bar. evertheless2 itis wise to draw the outline of the connector on the cast to avoid anymis u nder st a ndin g about its requir

e.Fig. 1& )*e completed +rame,or-6areful planning and clear prescription again result in the requiredmet al fr amew or:

.'57 *R+ T +,- D E T / ! 0 R/ !

12. System Desain

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