Prosthodontics (including DM) Flashcards
Major connector
Definition: connects parts of the prosthesis located on one side of the arch with those on the opposite side
Example lingual bar
Minor connector
Minor connectors are those components that serve as the connecting link between the major connector or the base of a removable partial denture and the other components of the prosthesis, such as the clasp etc.
K class?
Class I Bilateral edentulous areas located posterior to the natural teeth. Front
K class?
Class II A unilateral edentulous area located posterior to the remaining natural teeth. Side
K class?
Class III A unilateral edentulous area with natural teeth remaining both anterior and posterior to it. Kinda side
K class?
Class IV A single, but bilateral (crossing the midline), edentulous area located anterior to the remaining natural teeth. Back
Clasps must be
o Passive when seated (no orthodontic appliance type movements)
o Be able to flex (so the denture can be removed)
o Terminal 1/3 must be below the survey line
o Needs a opposing reciprocal component
Undercut engage: CoCr clasps
0.25mm
Undercut engage: SS clasps
0.5mm
Undercut engage: gold clasps
0.75mm
RPI system
To reduce the strength of the abutment tooth when the denture is loaded
o R – mesial Rest (changes fulcrum location)
o P – distal guiding Plate
o I – I shaped retentitve clasp (occlusal forces allow disengagement of clasp terminus)
Clasp assembly
o Retentative arm – below survey line so to engage the abutment
o Reciprocal arm – above or on the survey line
o Rest
o Minor connector
Disinfection of dentures
o 2 minutes in 10,000ppm (1%) sodium hypochlorite or sodium dichloroisocyanurate (Actichlor)
Support definition
Resistance to vertical load (occlusal forces during function) directed through denture to underlying mucosa.
Function of rests
Aim to apply forces vertically to the tooth (Rest seat - this needs prep (keeping to the enamel)
Tissue conditioners
Allows more equal distribution of load and assumption of more normal mucosal position (this is a temporarily placed material).
o They are commonly used in the situation that the tissues have trauma (maybe from an ill fitting denture), the dentist wishes for the tissues to recover during this time (ideally for the patient to not wear their denture – not popular) and so a compromise is to place this soft tissue conditioner to allow the soft tissues to recover.
Permanent resilient lining (soft lining)
o Ideally 2-3mm thick.
o Like tissue conditioners but these are permanent and are for patients who cannot tolerate a hard base, helpful to avoid pain from nerves.
o Elastic: cushioning effect
o Permanently soft: durable property overtime.
Permanent resilient lining (soft lining) - acrylic cold
temporary soft liner, done at chairside (softest of all four) – harden quickly due to leaching of alcohol and plasticiser to the saliva.
Permanent resilient lining (soft lining) - acrylic hot
lab processed, softness due to higher methacrylate and plasticizer (alcohol and plasticizer also leach into the saliva).
Permanent resilient lining (soft lining) - silicone
Water absorption of these materials puts them at risk of bacterial/fungal growth (candida albicans).
Heat cure
Cold cure: solidify at room temp, still are lab processed. Bond of this material to the PMMA plate is weak (often peels away).
Acrylic teeth
Attachment
* Chemical bonding of plate with the teeth.
Physical properties
* Suffer from abrasion
* Occlusal adjustment in the lab/chairside is much easier compared with porcelain.
* High cross-linking of the resins makes them resistant to crazing.
Porcelain teeth
Attachment
* mechanically to the denture base.
Aesthetics
* Slightly more translucent
* Depth of colour achievement
Sound
* Make a “clicking” when contacting
Physical properties
* Brittle – can fracture and chip.
Clinical application
* Not for patients with atrophic ridges as they transmit greater force through these soft tissues.
Paraffin wax properties
o Paraffin wax (mineral)
From petroleum residues following distillation.
Brittle at room temp.
Softens: 37-55 degrees
Melts: 48-70 degrees
Addition of microcrystalline to paraffin wax?