pros Flashcards
CoCr indications
greater strength
more hygienic design possible
acrylic indications
temporary denture
poor OH or likely to have denture additions
cheaper
inadequate support from remaining teeth alone (need mucosa support too)
kennedy classification
anatomical classification that describes the number and distribution of edentulous areas present
kennedy class I
bilateral free end saddle
kennedy class II
unilateral free end saddle
keneedy class III
unilateral bounded saddle
kennedy class IV
anterior bounded saddle
crossing the midline
craddock classification
simple classifciation based on support
craddock class I
tooth bearing
preferred - most comfotable, natural feeling (load transmitted via PDL)
craddock class II
mucosa bearing supporting
craddock class III
mixed - tooth and mucosa borne
support
definition
resistance to occlusal directed forces
prevents/resists movement and distributes load
support can be provided by
utilising hard tissues (teeth, bony undercuts) and large surface coverage (palate)
functions of rests
- Oppose movement of denture base towards tissue (support),
- help distribute/direct occlusal loads (down long axis of abutment tooth),
- provide anterior bracing,
- involved in reciprocation and indirect retention,
- determine axis of rotation for free-end saddle RPDs
how should rests be placed
Kennedy I/II - not immediately adjacent to saddles (free end)
Kennedy III/IV - immediately adjacent to saddles (bounded)
Craddock I - on tooth surface nearest base
Craddock III - on tooth surface not closest to base
rests
Components that provide mechanical support. Extension of the denture onto a tooth.
Described by the part of the tooth that they contact.
Rests in CoCr are rigid and strong and connect to base via connectors.
PMMA rests are flexible and have poor strength and are mechanically incorporated within the base and loads can cause stress
features f mucosal supported denture
As large an area as possible, base must be 3mm from gingival margin to adduct for soft tissue compressibility
every partial denture - Entirely mucosa-borne. Restores arch with contact points, wire stops prevent distal drift of most posterior teeth. Gingival margins not covered
retention
resistance to vertical displacement.
Mechanical, muscular, physical
direct retention
esistance to vertical displacement of denture. Clasps, guide planes, soft tissue undercuts, precision attachments
direct retention
esistance to vertical displacement of denture. Clasps, guide planes, soft tissue undercuts, precision attachments
indirect retention
resistance to rotation displacement of denture. Provided by placing components to resist rocking
ideal pattern of retention
Triangular, with one point on opposite side of the arch
retainers
Components that resist displacement of the denture
indirect retainers
Resist rotation about the clasp axis by acting on the opposite side to the displacing force.
fulcrum axis
Axis around which a tooth and Craddock III denture tends to rock when the saddles are loaded
mechanical retention
ways to provide
Clasps and guide planes
guide planes and how do they work
Retention through friction.
Supplementary direct retention.
Two or more parallel surfaces on abutment teeth used to limit the PoI and improve retention and stability
what do altered PoI provide
retention