Removable prosthodontics Flashcards
when setting teeth for a complete maxillary denture, what is meant by Watt and MacGregors biometric guides?
The biometric guide is one of the methods of designing complete dentures. It uses the remaining lingual gingival margin in the bucco-lingual placement of prosthetic teeth
In removable prosthodontics, what is the average horizontal bone loss for the fixed reference point in the following maxillary tooth positions; central incisors canines premolar molar
Central incisors 6.3mm
Canines 8.5mm
Premolars 10mm
Molars 12.8mm
In removable prosthodontics, what is the minimum data that should be recorded onto the record block?
- OVD; the distance between the jaws with the teeth in occlusion
- centre line;
- occlusal plane; the central occlusal plane indicates where the incisal level of the tooth will be
- High lip line
- Canine line; line extended from the inner canthus of the eye
- Arch form (width-lip support)
In removable prosthodontics, what is the minimum data that should be recorded onto the record block?
- OVD; the distance between the jaws with the teeth in occlusion
- centre line;
- occlusal plane; the central occlusal plane indicates where the incisal level of the tooth will be
- High lip line
- Canine line; line extended from the inner canthus of the eye
- Arch form (width-lip support)
What are some general features that should be present on a definitive impression?
- ensure the denture bearing areas are covered
- ensure there is a good functional sulcus present
- ensure there is good surface detail with no air blows
What features should be present on a maxillary definitive impression?
- coverage of maxillary tuberosity
- coverage of hamular notch
- extension anterior to the vibrating line for post dam
- functional depth and width of sulcus to create a good peripheral seal and ensure the hard palate and residual ridge are functional for primary support
What features should be present on a mandibular definitive impression?
- coverage of pear shaped pad and buccal shelf
- retromolar pad and extension into the linual pouch should occur
- functional width and depth of the sulcus
- ensure there is an area of primary support of the buccal shelf and retromolar pad
Kennedy class I
Bilateral free end saddle
Kennedy class II
Unilateral free end saddle
Kennedy class III
Bounded saddle
Kennedy class IV
Anterior bounded saddle crossing midline
Craddocks class I
Tooth borne
Craddocks class II
Mucosal borne
Craddocks class III
Combination of tooth and mucosal borne
What indicates the posterior border of the maxillary denture?
- The post dam which should sit 1-2mm anterior of the vibrating
line between the junction of the hard and soft palate. - The maxillary denture should be at the level of the Hamular
notch to produce a good posterior seal which is located
between the distal surface of the tuberosity and the Hamular
process of the medial pterygoid plate of the maxilla.
What impression materials are used for primary and definitive impressions?
- Primary impressions:
— Impression compound:
i. Non elastic material which records poorer
surface detail and this is why it isn’t used for
definitive impressions. It isn’t cheap to use and
can be messy.
ii. It is good for primary impressions due to the
high Mucocompressive viscosity
— Alginate:
i. Elastic material which means it will flow into
undercuts and can record surface detail for
primary impressions. - Definitive impressions:
— Silicone:
i. It is dimensionally stable and can be made into
a variety of consistencies which means it
accurately record surface detail
— Polyether/impregum:
i. It is dimensionally stable and has very accurate
recording of surface detail
— Alginate:
i. Can also be used for master impressions as if is
elastic so can flow into undercuts if they are
present.
What two things are required for accurately mounting study casts on an
articulator?
- Jaw registration
- Occlusal rims:
— Setting upper teeth to the wax rim and set lowers to
uppers in RCP
What is the relevance of freeway space in complete denture construction?
- The freeway space is the RVD – OVD which is ideally around 2-
4mm - If the freeway space is negative/reduced due to the increase in
OVD it will cause the dentures to click - If the teeth contact during speech there is not enough interocclusal
space which means the OVD needs reduced to give
more freeway space
What types of custom tray and spacer is used?
- Alginate use for special trays should have 3mm spacer
- Silicone/polyether use for special trays should have 2mm for
upper and 0.5-1mm spacers for lowers - Upper trays should have stops to the space prescribed in the
canine and post dam regions which will allow accurate
correction of the posterior borders of the tray and will
perform space for the impression material. - Lower trays should have stops to the space prescribed on the
retro-molar pad and on the ridge in the canine areas. This will
allow preformed space for the impression material.
What impression material is used for primary impressions and why is this
used prior to special trays?
- Usually alginate is used as it is an elastic materials so flows into
undercut areas. It gives an accurate record of surface detail for
impressions and is cheap and easy to use.
Why is silicone not Used for primary impressions for dentures?
- Silicone is dimensionally stable and is hydrophobic so can
cause small defects and blows. It is generally only used for
master impressions and not for the production of special trays
as it is very messy and technique sensitive.
What 2 areas of primary support are on the maxilla?
- Hard palate and residual ridge
Name 1 area of support on mandibular arch And what muscle lies adjacent to
this area?
- Retro-molar pad
- Muscles that lie next to it are:
— Laterally buccinator
— Posteriorly temporalis tendon
— Medically superior constrictor and the
pterygomandibular raphe
What is gypsum?
- Gypsum plaster is calcium surface dihydrate which is used to
cast a positive replica of an oral cavity. - Type 1 plaster/impression plaster is used in making primary
impressions of edentulous oral cavity in complete denture
fabrication. - Type III dental stone is an alpha form of calcium surface
hemihydrate which is used to make master casts
Describe Hanau’s quint?
- It is the inter relationship of 5 factors in order to maintain a balanced occlusion: — The saggital condylar guidance angle — The inclination of the occlusal plane — Compensating curves — The cusp height — The incisal guidance angle
What anatomical areas are required for retention, support and relief?
- Retention:
— Mandible – retro-mylohyoid space
— Maxilla – tuberosity, peripheral seal - Support:
— Mandible - Retro-molar pad, residual ridge, buccal shelf
— Maxilla – hard palate and residual ridge - Relief:
— Bony prominences (tori), high frenal attachments
In partial dentures, name the appropriate materials for the following undercuts;
- 75
- 5
- 25
- 75 wrought ss
- 5 gold
- 25 Co/Cr
