RPD - Design and Construction Flashcards
articulator
a hinged instrument to which the maxillary and mandibular casts are attached and which reproduces recorded relationships of the mandible to the maxilla
- assist the study of occlusion and the formation of the occlusal surfaces of prostheses and restorations
different types
surveyor
instrument used to survey casts
- may also be used to prepare parallel surfaces on restorations
drive the design for partial denttures
OSCE station
6 reasons why patients can have missing teeth
- caries (tooth decay
- periodontal disease (gum disease)
- endodontic infection
- trauma
- cancer
- congenitally absent (hypodontia)
4 consequences of missing teeth
- anatomical
- aesthetic
- functional
- psychological
what are the extra oral anatomical consequences of missing teeth?
change in facial appearance
- maxilla shrinks backwards
- mandible goes forwards
- exaggerate class 3
TMJ problems
what are the intra oral anatomical consequences of missing teeth?
- alveolar resorption
- tooth movement
- tooth wear
what is a term used for unwanted tooth movement due to missing teeth?
drifting
tiliting
how can aesthetics be effected by missing teeth?
loss of hard and soft tissue which support the face
how can function be effected by missing teeth?
mastication
speech
what is the most difficult thing for dentists to manage in regards to patients missing teeth?
the psychological effect
- mental health
- effect quality of life
7 ways we can replace missing teeth
- Resin bonded bridgework
- Conventional bridgework
- Implant crowns
- Implant bridgework
- Removable partial dentures
- Complete dentures
- Implant retained dentures
describe resin bonded bridgework
mesial cantilever is the most successful (abutment teeth on both sides of pontic)
fixed-fixed
descrive conventional bridgework
cantilever
fixed-fixed
need to do a lot of preparation
- more destructive
retainers usually metal ceramic crowns
what is the preferred method of placing an implant crown?
with a screw rather than cement
- can remove easier if something goes wrong
what is implant bridgework?
similar to conventional bridgework apart from use implant screws on abutments rather than retainer clasps
removable complete denture
conventional denture
- no attachments for stability
implant retained complete denture
abutments are attached to implants to be attached
- ‘snaps in place’
implant supported complete denture
screw retained and removable
what does ‘saddle’ mean?
area with no teeth
bi-lateral free-end saddle
anterior teeth only, no posterior teeth on either side
uni lateral free-end saddle
anterior teeth and one side of posterior teeth present
bounded saddle
gap in running row of teeth
e.g. between canine and molar (missing premolars); between canines
do we replaces all missing teeth?
no
depends on ones missing (need 20 teeth according to WHO)
shortened dental arch
A dentition where most posterior teeth are missing
- Satisfactory oral function without use of RPD
Priority given to maintaining an anterior and premolar dentition in one or both jaws
- In the right circumstances, non-replacement of posterior missing teeth can provide a stable and acceptable dentition
3 ways to extend the shortened dental arch
bridgework
implants
RPD
what are the 3 classes of support a removable partial denture can have?
- tooth borne
- mucosa borne
- tooth and mucosa borne
what is tooth borne support?
everything rests on teeth (no free end saddle)
desirable
what is mucosa borne support?
everything rests on mucosa
what is tooth and mucosa borne support?
mixture of retainers on teeth and RPD resting on mucosa
what type of material (base) can you get for an RPD?
- acrylic
- cobalt chrome
what are the 5 stages in patient assessment?
- history
- examination
- special investigations
- diagnosis
- treatment plan
what do you need to get when taking patient’s history for RPD?
Full denture history
- Why were teeth lost? How long have they worn dentures for? How many dentures have they had? Have they got a favourite denture? Previous denture causing problems? Have they got a preferred design? Which do they prefer -metal or acrylic resin denture?Periodontal disease? (Means ridges going to change)
Medical history
- particularly identify problems which could affect treatment; Arthritis, Neuromuscular, Mucosal disease, Xerostomia (denture may not stay inn well, uncomfy), Osteoporosis/bisphosphonates
Social history
- esp hobbies - wind instruments
extra oral points to look for in the RPD patient examination
- Lower facial height - Too short dentures would mean lower facial height reduced
- Nasio-labial angle
- Limited Opening
- Any abnormalities
- Smile line
- Aesthetics of existing dentures
intra oral points to look for in the RPD patient examination
General Examination
- Periodontal status
- Endodontic status
- Caries
- Tooth wear
- Indirect restorations
Edentulous spaces
- Number
- Position
- Length
- Ridge form
- Displaceable tissue
Occlusion
- Occlusal vertical Dimension
- Occlusal contacts
- Freeway Space
kennedy class I
bilateral free end saddle
e.g. only 4 to 4 present
kennedy class II
unilateral free end saddle
missing one side of posteriors
kennedy class III
uni lateral bounded saddle
missing some posterior teeth on one side but have the 7 or 8
kennedy class IV
anterior bounded saddle
missing incisors
craddock class I
Saddles supported on both sides by substantial abutments
All tooth borne
craddock class II
Vertical biting forces resisted entirely by soft tissues
All mucosa borne
craddock class III
Tooth supported at only one end of the saddle
Tooth and mucosa borne
9 points to look at in denture examination
- Support -The resistance to vertical movement of the denture towards the tissue
(too supported teeth resist movement) - Retention - The resistance to displacement of the denture away from the tissue
- Stability -The resistance to horizontal (lateral) movement of the denture
(Is occlusion meeting directly) - Aesthetics - Primary for patients
- Extension - How far denture base extends
- Occlusion -bite
- Material
- Design
- Condition of teeth and base- How long in at a time and age of denture – assess teeth wear, fractures of denture
what is denture support?
The resistance to vertical movement of the denture towards the tissue
Too supported teeth resist movement
what is denture retention?
The resistance to displacement of the denture away from the tissue
denture stomatitis
mixed bacteria and yeast infection
can occur if wear denture overnight
asymptotic infection if mild
- can cause chest infection
abutments teeth requirements
- structurally sound, with satisfactory appearance (Really strong teeth either side to make bridge, Need to pick best condition teeth as additional forces on them)
- in good alignment and position
- any previous restorations and endodontic treatments are satisfactory
- tooth roots and supporting alveolar bone are adequate (You don’t want to use teeth with bone loss. No RCT, need good bone support)
- soft tissue of the edentulous ridge is satisfactory in quantity and quality
what special investigations need to be undertaken for abutment teeth? (4)
- Periapical radiographs
- Sensibility testing – blood and nerve supply (EPT, Ethyl chloride)
- Surveyed study models
- Clinical photographs
what is denture over extensions
too much material
what is under extension of denture
palate or flanges are too shallow which causes air to undermine the denture, therefore, it drops or has excessive movement.
Under extension can also cause a gagging sensation.
