Major Connectors Flashcards
major connectors must be what to distribute stress?
Rigid
- pushing one object against another object will distribute stress is both objects are RIGID
general description of A/P palatal bars
- most rigid
- most common
- no right angles between bars
- bars are perpendicular to main suture
describe the anterior bar in an A/P palatal bar
broad and thin
between rugae
6mm from gingival margin
describe the posterior bar in an A/P palatal bar
narrow and thick
1/2 tear shaped
thickest at posterior
ant to junction of the hard and soft palate
broad palatal strap is most common when?
*used ONLY when few teeth missing (1 finger width)
pt. missing 1/ 2 pre molars on either side
- has to be thicker because only one bar
thickness in broad palatal strap?
has to be thicker because single bar but this can interfere with speech problems
anterior border is placed where in a broad palatal strap?
as far posterior as possible
-
posterior border is what in broad palatal strap?
is perpendicular to median suture
NEVER CROSSED PALATE ON A DIAGONAL
when is full palatal coverage usually used?
ideal for patients with kennedy class I
- when distal extensions are needed
- posterior half looks like a complete denture
T/F full palatal coverage can be all metal
TRUE
- but we do half and half
- metal is good thermal conductor but is non-adjustable
- cannot put post dam on full palatal coverage
does full palatal coverage include post dam?
yes – looks like complete denture in the back
does full palatal coverage cover tori?
it can with acrylic
kennedy class I uses what for restorative?
full palatal coverage
horseshoe use?
tooth borne involved
posterior molars
best with many guide planes
*used when there are tori that are inoperable at the junction of the hard and soft palate (**so when a/p palatal bar is not able to be used)
gaggers last resort
a/p palatal bar looks like what with a posterior bar?
a horshoe
but anterior bar is more thin which is advantagous
success with horshoe?
less - it covers a poor amount of surface are and rotates horizontally
thickness in horshoe?
needs to be thick to maintain rigidity but can cause speech problems
shape of lingual bar
half tear shaped like posterior bar on the maxillary arch
lingual bar description
- most common – used unless cannot use
lingual bar implication with tissue and distance?
the superior margin is 3 mm FROM FREE GINGIVAL MARGIN - at a minimum
lingual bar width
3 mm at least
lingual bar requires what space? compared to maxillary?
6 mm fold depth – so during tongue movement
- needs to be 3 mm away from free gingival margin and the width is 3 mm
- so need 6mm IN FUNCTION
maxillary is 6 mm from the free gingival margin
shape of lingual bar
1/2 tear shaped with bulk inferior
difference between maxillary and mandibular partials in terms of tissue
mandibualr needs tissue releif
use of lingual blanket (7)
- do not have 6 mm in function
- non operable lingual tori
- increase distribution of occlusal load
- shallow floor
- high lingual frenum
- questionable prognosis
- splinting a week teeth
contact with a lingual blanket?
contacts the teeth but not the gingiva
what does a lingual blanket require?
rest seats on all lower anteriors – distribution of the occlusal load
inferior border of a lingual blanket?
still needs to be compatible with tongue movement - so at a depth that is compatible with this (does not follow same rule as 6 mm in function as the lingual bar)
maxillary and mandibular reltionship to soft tissue and why
- maxillary CONTACTS TISSUE
- mandibular is RELIEVED from tissue
this is because there are differences in tissue type and tissue movement
What do we do to maxillary casts to ensure more contact?
we score it and bead it
beading use?
only on maxillary and we do this everywhere where we do not have a finish line
- kind of like mini post dams to better adaption
- better adaption
- better contact for major connectors
- do not want too tight
relief wax relationship to upper and lower partials?
LOWER ***
- need to relieve the tissue on mandibular partial s
- 28/ 30 gauge
- very thin but we need it
over seating on mandibular?
rest and rest seats hold the framework are not perfect then and impinges on pt. tissue – not good
what do we do about tori
rule of thumb - we never ever put over tori
most can be restored around them
- so design
- acrylic can go over
if tori far posterior on maxilla?
have to use horshoe because posterior bar / metal cannot go over tori only acrylic can be placed over tori
mandibular tori present tx of choice?
- surgical removal (most of the time lingual bar cannot be placed with tori present)
- lingual bar
mandibular tori generally interfere with the inferior border of the connector
- if un-operable then we choose lingual blanket if it can be avoided
lingual tilt implication on lower maor connectors
major connector may interfer with the tongue
- also may be too far from the lingual tissue
- need to bring surveyor to the lingual as well
order of clasp selection for distal extension rotating partial is?
- RPI
- Combo
- Bar
- RPA cast
definition of finish line
a butt joint (90 degrees) at junction of metal and acrylic where major connector meets the denture base
- prevents leakage at their interface
components of finish line
internal and external
external - finish line is from a plastic pattern
internal - finish line is from a wax spacer
which finish line is never used with a tissue stop
tooth to tooth
- these finish lines are for tooth borne spaces only
the three types of finish lines
- tooth to fold
- tooth to notch
- tooth to tooth
tooth to fold finsih line use?
for lower distal extensions major connectors
tooth to notch finish line use?
for upper distal extension major connectors
tissue stops in relation to tuberosity or retro molar pads?
tissue stops end just before the start of the tuberosity and the retromolar pad
- should NOT end directly on top of them
use of tissue stops on the maxilla?
optional
- this is because the major connector contacts the palate - it is dependent on the size and rigidity of the maxillary major connector
use of tissue stops on the mandible
required – the mandibular major connector is releived from the mandibular tissues
- only part of the distal extension that will contact the tissue
what do single tooth spaces often need?
since they have less surface area - and thus less are to chemically bond to a denture they may require aditional MECHANICAL REINFORCEMNT against the occlusal forces
single tooth space in the anterior? posterior?
anterior – steel’s facing
posterior – tube tooth
clinical steps in steele’s facings for anteriors (what you do)
- mould (you select) – select the size and mould
- Mount
- matrix
general steps in making a steele’s facing
- tooth set on articulator
- matrix made of plaster
- tooth and matrix sent to lab
- lab trims tooth and places retentive slot
- wax up of lingual done with matrix
plaster matrix is used for what in steele’s facing?
used to position the LABIAL PORTION of facing
refractory cast part of what?
labratory steps in setting an anterior steele’s facing
components to a tube teeth
**for posterior
there is a NAIL HEAD on the meshwork
the tooth is hollow ground on the under-surface and goes over the nail head
slots are placed where for tube teeth
on the two proximal sides
how are facings added
by cementation or curing
how are tube teeth added?
added during processing
T/F the approach arm and nail head can occupy the same space
TRUE
how do you notify lab for a steele’s facing
add it to the MODIFICATIONS list
- only tooth on there we need to note for modifications
what do we draw on paper?
on cast (3-D)?
why important?
on paper
- tx plan record
- lab prescription
on cast (3-D) - exact location for frame fabrication
- know the exact location of framework and where undercuts are
outline of major connector is scored to create what?
create a BEAD which maintains the tissue contact
- maintains the POSITIVE tissue contact w/ the palate on the MAXILLA
drawing must avoid what?
the rugae
what is the importance of drawing finish lines
a finish line “captures” the acrylic and encloses the acrylic with a metal ‘fence”
which types of finish lines are upper only? lower only? both?
tooth to tooth = both / either
tooth to fold = lower only
tooth to notch = upper only (like at the hamular notch)
describe the full palatal coverage finish line
- has 3-sided finish line
- each side begins as a tooth-to-notch line
- which goes half-way to the notch - then both sides are joined across the palate
when do you add the meshwork to your drawing?
after the finish lines are drawn
- is added to the finish line drawing in the form of attachment “loops”
how are facings drawn?tube teeth?
they are drawn like CINGULUM RESTS
tube teeth are drawn as a side-ways “T”
when drawing clasps where do they begin and end?
begin - at retentive tip
end - at point of origin
what is the sequence of drawing?
F - finish lines and tube teeth
R - Rests and steele’s facings
M - Major connector
C - Clasps
