wk6: RPD Design PT 2 Flashcards
What is Kennedy Class 1
Both Free end saddles
What is Kennedy Class 2
single free end saddle
What is Kennedy Class 3
posterior bonded saddles
What is Kennedy Class 4
anterior bonded saddles
Class 4
Class 3
Class 1
Class 2
Considerations for RPDS
should only be provided on patient request
of dentures patient has had in the past
Problems Edentulism can cause (over eruption risks)
replacement of teeth should have purpose
(don’t replace 18)
not all missing teeth should be replaced
patients main demands are appearance and security
indications for RPDs
lost of teeth is restricted to long edentulous bounded saddles
several short spans are to be fixed
excessive anterior and posterior tooth loss occurs in combination
restoration of soft tissue bulk
restoration of occlusal face height
what are the two major categories of RPDs
- Tissue borne
- Acrylic base and gets most of its support from underlying oral tissues - Tooth Borne RPDs
- Chromecobalt, get most of its support from the remaining teeth (occlusal rests)
What would make you choose a chromcobalt choice vs Acrylic base RPD
Chrome cobalt
- Good Teeth to distribute load
best of the best
Acrylic
- Lack of support of Teeth
- patient unsure of denture( good starting denture for first time patients)
-cost of Chrome Cobalt too high
- allergies to chrome cobalt
What is the most important thing to ensure stability of partial dentures
Extending the dentures into the full denture bearing anatomy. Capturing all 1st and 2nd stress bearing structures is essential for full stability.
Denture bearing area is just as important as clasps
what type of assessment is required to be done prior to RPD treatment, and why
Periodontal assessment
- see if there are periodontally involved teeth the can’t be included in the design,
- understand the important teeth necessary to provide support for the denture.
- Radiographs can help you know the Bone assessment for proper support of the denture
what are key anatomy structures that should be noted in the design process for both the maxilla and Mandible RPDs
Mandible
- floor of mouth and lingual frenum (allow for major connector placement)
-retromolar pad and sulcus depth
maxilla
- Posterior extensions of distal extensions should point to hamular notches
-vibrating line
assess tori, height of floor of mouth, frenal attachments these will impact the type of major connectors and direct retainers selected.
what are the clinical stages of RPD
- primary impressions
- study casts prepared
- design of RPD and Tooth Preparation
- special trays and secondary imp
- try in of metal frame work and Bite Reg
- tooth/ aesthetic try in
- fit and adjustment
8.Review
what are primary impressions used to record. and what can be down to help capture difficult areas?
Record the full denture bearing area.
periphery wax and putt/compund can be used to help extend a tray and capture unsupported areas. (2 stage extension)
What is the purpose of special trays and secondary impressions
Needed for working impressions, Need an accurate impression to capture function depth and width of sulcus,
what depth should the tray be in comparison to the sulcus depth
2mm short of sulcus depth
what are the stages of RPD design (what do you pick first)
- saddles
- rests
- clasps
- indirect retention
- bracing
- reciprocation
- connectors
what is the purpose of surveying
identifies favourable path of insertion
aids in prep for guiding planes
identifies undercuts
helps choose type of direct retainers
blocking out of undesirable undercuts on master casts
in mandibular RPD what is an essential characteristic for a Saddle
Saddle must be fully extended in the distal extension edentulous area/retromolar pad
what is the function of rests
transmit occlusal loads from the denture down the long axis of the tooth.
what is a guild plane and what are their benefits
Parallel axial surfaces on abutment teeth (Medial/Distal surfaces typically) usually flat surfaces parallel to the long axis of tooth.
benefits
1. increase stability:
- resisting displacement of denture in directions other than along the planned path of displacement
- Reciprocation
- guide surface allows a reciprocation component to maintain continuous contact with a tooth as the denture is displaced occlusally - prevention of clasp deformation
- in ensures the patient removes the denture properly
- won’t cause claps flexure and failure in removing them - improved appearance
- permits an intimate contact between saddle and tooth which allows the one to blend with the other.
what does the RPI system include
Medial rest, distal plat and I-Bar
what is the function of the RPI system
reduce torsional forces places onto a tooth which abuts a free end saddle.
what is the altered cast technique
Aims to reduce the degree of compressibility in function and reduce the springiness of the denture
- can improve the fit while under compression
- stable during mastication
what are the issues with altered cast technique
dentures may displace at rest,
often over and under extended.
What is the function of claps
Provide direct retention for the denture
describe how a clasps sits when on a tooth
only the last 1/3 of clasp is engaged in the undercut. the first 2/3 are able the undercut to provide bracing and support
what are some things that clasps require
reciprocation: prevents displacement of a tooth when a claps is disengaging from an undercut. Limits orthodontic movement and trauma.
Rest: clasps should always be supported with a rest
what is indirect retention
Retention that is provided to resist rotation of the denture about an axis during mastication which is achieved by (clasps, rests, major and minor connectors and saddles)
what are the functions of a major connector
- links saddles and unifies structure of the RPD
- Provides bracing and support by distributing functional loads to teeth/mucosa
- provides indirect retention by contacting surfaces and palatal coverage.
3 keys for designing for health
5 keys for stress distribution and support
3 keys for security
