pros RPD Flashcards
consequences of missing teeth
- changes in facial appearance
-TMJ problems
-alveolar resorption
-tooth wear
-tooth movement
-mastication effected
-speech effected - psychological impact
what is shortened dental arch
- kayser 1981
- 20 teeth - 5 to 5 lower to upper ratio
what is denture support
- resistance to vertical movement of the denture towards tissue
provided by rests
what is denture retention
resistance to displacement of denture away from tissue
what is denture stability
- resistance to horizontal movement of denture
what is Craddock class I
- saddles supported on both sides by substantial abutment
- tooth borne
what is Craddock class II
- vertical biting forces resisted entirely by soft tissue
-mucosa borne
what is Craddock class III
- tooth supported at only one end of saddle
- tooth and mucosa borne
what are the Kennedy classifications
- Kennedy Class I - bilateral free end saddles
- Kennedy Class II- unilateral free end saddle
- Kennedy Class III - unilateral bounded posterior saddle
- Kennedy Class IV - single anterior bound saddle crossing the midline
what is a clasp
- engages tooth and enters undercut for retention
where can rests be placed
- occlusal
-cingulum
-incisal
what is a minor connector
components that serve as the connecting link between the major connector and other components of a partial denture such as the clasp assembly and occlusal rests
signs of overextension
discomfort, looseness in function, speech issues, impingement on frenal attachments, difficulty swallowing and gagging
signs of under extension
looseness in function, traumatic ulceration, food trapping under the denture
what type of articulators are used for dentures
- simple hinge
-average value
methods of denture retention
- clasps (mechanical)
-muscular forces (shape of denture) - physical forces (coverage of denture)
what is indirect retention
- resistance to rotational displacement
reciprocation
prevents a clasp arm moving the clasped tooth and weakening PDL
what is bracing
resistance to lateral movements
maxilla - palate and alveolar ridge
major connector can help too
which denture is easier to add on teeth to
- acrylic
upper major connectors
- bar design (strap) - broad , doesn’t interfere with tongue
- horseshoe - works well keeps palate clear
- ring denture- stays away from gingival margins
-plate design
lower major connectors
- bar (sub lingual or lingual)
-plate
function of rest seat
- produce favourable tooth surface for support
- prevent interference with occlusion(overeruption)
- reduce prominence of the rest
- direct force down long axis of tooth
-can provide indirect retention
what is guide plane
two or more parallel axial surfaces on abutment teeth, which limit the path of insertion of a denture, they may occur naturally but more often they need to be prepared
what do guide planes provide
- increased stability
- reciprocation
- prevention of clasp deformation
- improved appearance
how big is spacer
3mm
how far away from sulci should tray periphery stop
2mm
what are non elastic impression materials good for
- for free end saddles
how to block out large interdental spaces
ribbon wax
what is occlusion
the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues
how to record the OVD
- willis bite gauge or dividers
how to record free way space
RVD - OVD = FWS
what is Ala-tragus line used for
- guide to position of occlusal plane
what is possets envelope
extremes of mandibular movement
- border movement of mandible in sagittal plane
what is ICP
- maximum interdigitation of teeth
- tooth position regardless of condylar position
what is RCP
- most reproducible
- 1mm posterior to ICP
- first tooth contact when condyle of mandible is in retruded axis position
what are index teeth
- teeth that contact in the ICP
materials for interocclusal record
- wax wafer
- bite reg paste
what is hue
colour
what is chroma
conc or saturation of Hue
what is value
lightness of hue
what can help to diagnose pain at denture insertion
PIP
what you should be recording on upper impression
- post dam
- maxilary tuberosity
- buccal shelf
- hamular notch
- frenum
what you should include in lower impression
- lingual sulcus
-buccal sulcus/shelf - retromolar pad
-frenum
what is post dam
ridge on posterior border of denture which helps posterior seal
- junction of hard and soft palate
different undercut gauges for claps
- 0.25 - cast cobalt chromium
- 0.50 - cast gold alloy
- 0.75 - wrought stainless steel
why survey a cast
- the optimum path of insertion
- design, material and position of clasps - identify bulbous part of tooth
surveying what are the analysing rod, graphite marker and undercut gauge
what is path of insertion
- path followed by a denture from its first contact with the teeth until its fully seated
- may be multiple paths or occasionally a rotational path of insertion
what is neutral zone
space between tongue and cheeks where opposing muscular forces are in balance
how long does CoCr clasp have to be
15mm long
what is RPI
used in lower free end saddles to help prevent stress on last abutment
mesial Rest (occlusal)
proximal plate (adjacent to saddle)
I bar clasp (gingival approaching)
what are types of indirect retention
- Rests
- Saddle
- Denture Base
- major and minor connectors
what happens if length and thickness of clasp is adjusted
- if length is increased the clasp becomes more flexible
- if the thickness is reduced by half the flexibility is increased by factor of 8
when is a clasp active
when it flexes over bulbosity
where should the terminal third of occlusal approaching clasp be
- undercut area
how many points of retention in RPD
-3 points
-triangular retention
when would acrylic be chosen over CoCr
-immediate denture
-addition
-diagnostic denture - increasing OVD
-young person
-arthritis
how much space is needed for lingual bar
8mm space
tooth support vs mucosal support
tooth support
- transmits load via PD membrane
-comfortable
-protects soft tissue
mucosal support
- large area as possible
-possible damage to gingival margins
how much load can healthy tooth carry
1.5
how far away should a base be placed from gingival margin
3mm
what provides support
RESTS
where are rest seats usually placed
- usually occlusally to direct occlusal forces down long axis of tooth
- in bounded saddle places immediately adjacent to saddle
-if free end saddle rest isn’t placed adjacent
where should rest be positioned in tooth supported bases and tooth /mucosa borne
- tooth - tooth surface nearest base
-tooth/mucosa - tooth surface not next to the base (opposite side of tooth from saddle area)
what are mechanical forms of retention
- clasps, guide surface, precision attachments
physical retention
adhesion - surfaces forces of saliva on denture and mucosa
cohesion - focus within saliva, viscosity
gravity
what is direct retention
resistance to vertical displacement
considerations when choosing a clasp
- position of undercut
-health of PDL
-shape of sulcus
-length of clasp
-appearance
-occlusion
