Design Flashcards
kennedy class i
bilateral free end saddle
kennedy class ii
unilateral free end saddle
kennedy class iii
bounded saddle
kennedy class iv
anterior bounded saddle that crosses midline
how do you prioritise what saddle to name using the kennedy classification
always use lowest classification possible then add a modification number for each additional saddle
craddock class 1
tooth borne - saddles supported on both sides by abutments and saddles are not more than 3 teeth wide
craddock class 2
mucosa borne - vertical biting forces resisted entirely by soft tissues
craddock class 3
both tooth and mucosa borne
if considering an abutment for a clasp what else should the abutment have and why
a rest, to prevent clasp sinking to gingival margin
gingivally approaching clasp
approach undercut via gingival margin and do not cross maximum bulbosity of the tooth
useful on narrow teeth i.e anteriors and pre molars
occlusally approaching clasp
approach undercut from occlusal side of survey line therefore crosses maximum bulbosity of the tooth
commonly seen on molars
ring clasp
also known as self reciprocating clasp
type of occlusally approaching clasp
what is the recommended pattern of retention
triangular
however some situations only allow for two
how are rests named
according to where they sit/ contact the tooth e.g occlusal, cingulum , incisal
do rests work best on metal or acrylic bases
metal as they are an integral part of the framework whereas on acrylic bases they need to be added and have potential to weaken base
where are the default positions for bounded saddle rests
immediately adjacent to the saddle
where is the default position for a free end saddle rest
opposite side of abutment tooth to saddle
why should rests be of sufficient enough size that they extend near the midline of the tooth
to ensure they can apply/ transfer load down long axis of tooth
name 3 risks associated with preparing rest seats
dentine exposure
destruction of tooth surface
loss of occlusal stop when denture not worn
Name 5 benefits of occlusal rests
prevent movement of rpd towards mucosa prevent overerruption of unopposed teeth distribute occlusal load possibility of indirect retention helps determine axis of rotation
indirect retention
resistance to rotational displacement
retention
resistance to vertical displacement
reciprocation
prevents clasp arm moving clasp tooth
bracing
resistance to lateral movements
on what type of saddles is indirect retention more of an issue
free end saddles
indirect retention not really an issue on bounded saddles
what are examples of indirect retainers
rests, connectors, saddles
why should there be good clearance between the gingival margin and a reciprocal arm
to ensure maintenance of good oral hygiene
on what type of rpd is bracing not a common problem
rpds that have components on both sides of the mouth
