Tuesday, March 24, 2009
In the name of allah ..
In today's lecture we will going to talk about connectors, well the doc.
Hopes she makes a major connector with us :D ..
A Connector: is some thing joining many things together, so in dental:
prosthesis that unites its components.
We also hv sth called a major connector: which is unifying all the parts
from the left to the right. Or it could be by a minor connector : which
joining clasps , rests, or retainers to the main structure.
♣What's are the functions of these connectors?
1. They transfer the functional forces to the abutment teeth.
2. To connect all RPD components together.
There are many requirements for a major connector:
❶ They are located on hard tissue, supported by the rests on the teeth.
❷ They should be rigid enough to could hold forces , and not to week
under the pressure.
❸ They hv a relief under the connector. Why? We don't want to
traumatized the underneath soft tissue.
where are the soft tissue are really thin & easily traumatized?
It's over lesions like :
1. Palatal tori.
2. Mandibular tori.
3. A mid palatine suture.
❹ it should hv No food trapping under it, to prevent bad effect.
❺ it's smooth & free from any sharp edges that can cause injury to the
❻ Has a design that is periodontaly safe.
- should not impinge on moving tissue.
- should avoid pressure on the gingiva by uncovering relief.
❼ They hv borders contoured, for the p't tolerance.
భ Types of a major connecters : it comes either as a Bar or a Plate .
they could be either made of metal or acrylic.
- what type of metal we used in a P.D ?
1. co-cr alloy .
3. Gold type 4.
In the Maxilla :
1.we look at Plates thet covering the whole palate or apart of it .
2. they could be describe as a strap that is a bit narrower& less than
12 mm wide.
3. Bars if they hv a half round section.
These straps, bars, and plates , if they are partially placed they
come in anterior area , posterior area , middle area , hors shoe , or
anterio-posterior , we will seen them in a moment .
♫ Selection Criteria :
Hw do I chose which major connector ? wt's the criteria that I need
to depend on it ?
1. Am I looking at the location of edentulous areas?
2. Amount of support that's required.
3. Rigidity degree.
4. P't preference, because not all the p't can tolerate a whole
5. Anticipated tooth loss, I'm expecting that some teeth will lost.
6. Location of fulcrum line.
7. Extent of the saddle area.
8. previous experience from other dentures.
Let's go on every one (slide No# 11)
- (the first pic.) this is a major connector , where you clearly see
that it's covered all the hard palate , it could be in the rugea area
or not .
- If the whole hard palate covered, this is what we called it a
complete palatal coverage.
It isn't a plate , it's covering the whole palate.
The complete palatal coverage has an advantages that it will act as
a direct retainer. For example, If we hv a denture that has sth
flipping from the posterior part , what will happened to the anterior
It will resist this flipping away from the tissue.
1. so it will act as a direct retainer.
2. it will cause a good retention, if you remember if we covering
the surface area which includes close contact, a thin saliva in
btw that will provide adhesion , cohesion , & seal.
3. It is give a good load distribution.
4. If I lose one of the abutment , I could simply add to it .& usually
we use it when we have a :
❶ palatal defect : suppose that the P't has a cancer, and he lost his
palate , so what type we will use? It will be palatal coverage.
❷ If we hv along span edentulous cases, and I want the load to be
➌ When maximum support is required.
- This is a partial coverage ( the 2nd pic. In slide NO#12) meaning
that the rest part of the hard palate is exposed. It could be used
when the p't can't accept the complete coverage.
- It's determined by the amount of bone & the support from the
abutment. For example if this tooth is weaken and the other
tooth also weaken ( when the 1st tooth is in the right and the
other in the left) I would like to hv more support from the mucosa
, that the plates providing this support.
- It can hold higher occlusal forces and mostly used it with longer
- We call it plate not covered , because we can see part of the
☻There is sth called a Split coverage when the denture hv a split
(space) btw its two parts. There is a pic. In (slide NO# 15) the doc.
Drawn this space in the middle cause she didn't find an image
producing the split coverage) Any way …
This part is a whole plate , and the other part is another one , the
area btw them Is a split , here (in the post.) where the two plates
joints. We get a benefit from the split over here , wt's the benefit if I
separate the two parts of the denture , then joining them posteriorly
? It will be more flexible , and I'll be reducing the disturbing forces
on the other side . Suppose that I hv all the teeth in the right are not
present , and in the left they all present , and I'm going to send a
clasp from the left to the right to hold there . What will happen when
all of these teeth are not present? The denture will be continuously
rocking in the p't mouth, he can't bite on them either.. So when I do
a split btw them , when the p't is biting on one part it's the only part
is moving . It benefit us in relieving the pressure on dentition where
we hv heavily occlusal forces in one side.
► another type of a major connector called : Strap. It's called
strap when it's less than 12 mm in diameter , It's a flat piece . when
it's larger we call it plate.
▒ It could hv a Horse shoe palatal coverage type : it's include
an anterior plate & two lateral plates and the palatal area is not
We need this coverage when we hv a tori. It's a bony prominence
that we can't cover it with a metal so we relief it , by using a horse
shoe coverage .
◙ This is another modification done in this plate, they made the
plate anteriorly on the teeth , and split it from the middle because
the p't has a diastema (slide NO# 17) this split done for esthetics
☺ This is a Bar: it's called bar when it's hv a half round shape, or
half ova shape ( It isn't flat) We change it from flat into sth half
round cross section , Anterio-posterior it's thinner , or narrower but
in cross section it's thicker, we want to decrease the size of covered
area and, at the same time having some strength .
╪ Anterior posterior Bars: It's cross section have around shape
, or a pear shape , that can used to avoid area that have tori , or
when we want to increase rigidity : suppose that the p't can't
tolerate sth over the palate, but this is thin and could be bend , so
we want it more rigid in posterior , for that we will leave the area in
the center exposed , and but the bar just in the anterior and
$$ The table in the slide# 20 : have the differences btw each types
of bars , so you can referred to it :P ..
There are some design consideration that we want to put it
in our mind :
1. we want to be friendly with the gum, we want to protect the
gingiva and the periodontium that surrounds the abutment.
Imagine that the p't lose his teeth and doesn't have any prosthesis
in his mouth, that means that he have the ability to lose his teeth ,
now we put sth inside his mouth , what will happen to the oral
hygiene and susceptibility for the caries and plaque accumulation ?
It will increase , so we should design the denture in away to be
friendly to the gum & what's beneath it. So hw do we protect the
gum ? simply by going away from the gingiva by 6 mm to allow the
tongue to clean the debris in btw , but if I want to cover it , I should
go over the marginal gingiva 3mm (which what we did in the lab )
When we crossing the gingiva & make the minor connector crossing
the teeth , we do a relief.
What's a relief? Before designing the metal we place sth to cover
the marginal gingiva which is the wax to go to the tooth directly with
out reaching the gingiva and traumatized it.
- Why do we relief by wax not plaster?
What we will do to the cast not the same , we use a cast that
tolerate a very high temperature called ( Refactory cast ). If I put
this stone cast in a thermos to melt the metal by high temp. , It will
dry out then fractured , I'll lose it .I'm going to duplicate the stone
cast before making another cast , I block out all the marginal
gingiva area and make it relief ,, because I'm not going put this cast
in a high temp. I can relief it with wax so I eliminate these areas of
under cut, then make the denture.
2. the fitting surface should not at all be polished , because we
want the exact tight fit full over except for the gingival margin
when we crossing the gingiva , we polished the denture from
beneath.(slide NO#22 the 2nd pic. ) This is a part of a denture
from the fitting side ( in the center isn't polished, because this is
the soft tissue morphology , we want it very close adaptation to
get the benefit of saliva going in , and having retention. But in
the marginal gingiva if we leave it like in the center it will injured
the p't , so do you see the shining over the marginal gingiva (
here is polished).
3. We don't bead. The Bead we do it at the margins posteriorly ,
and stop doing it when we reach the marginal gingiva, I will tell
you what's the bead in a moment.
4. We increase the p't acceptance by doing :
❶ all the borders should not be a sharp angles, they will be all
tapered , the tongue should not touch any sharp area . all the
margins should be flushed smoothly.
❷ It's smoothly finished in the polished area.
❸ Pass within the rugea valleys (slide No#23 the left pic) see the
rugea if I'm going to cover it , I should end run with one of the rugea
valley , runs in a lateral way , so the p't can tolerate it.
➍also should not go to the vibrating line because it will cause
☯ This Is the Beading (slide No #24)
What is the beading? Do you remember in C.D we make the post
dam in the cast ?we trim from the cast to make the denture thicker
in that area toward the tissue, and this provide a good palatal seal ,
we need the same seal in the metal, but we don't make it as wide
as what we done in the C.D. We make a very thin line running a
1mm over the posterior surface , it isn't flat you can see there is a
small extra material ( the last part post. In the denture) which we
create it by curving in the cast. (slide No#25) This is another
denture you can see clearly the beading , so the beading done in
the major connector ant. , post. , areas, but once we reach the
gingiva we stop our beading process about 6mm away from it .
♕ (slide No#25) This is a denture that have a polished surface
posteriorly . Is this just the thickness of the denture? No, the metal
is going thicker toward the tissue , by carving a line like the ditch
() (خندقin the cast to let the metal going in and make a good seal.
Notice that the dimension is less than 1mm , maximum should be
1mm , so it isn't like the post dam area which is 1.5mm . Notice also
in the same picture how the metal is run with the valley of the rugea
☂☁ What are the Mandibular connector ?
❶ Lingual bar.
❷ Sublingual bar.
➌ Lingual plate.
➍ Buccal plate.
➎ Dental Bar.
〄 The Lingual Bar: is the most commonly used . It has a half
pear shape , should have a relief under the soft tissue ( slide
No#27) could we do this ( a lingual bar) using an acrylic?
No, we can't use it to do a lingual bar , but we can use it to do a
lingual plate instead of it. ( which is what we do in the lab).
- It should be away from the soft tissue by 3mm , some books
says 5mm , others say 6mm , any way the more we are away
from the soft tissue & the gingiva the better.
- Some times we can't use the lingual bar specially when we have
a shallow sulcus, there is no place to put this bar . See the
distance btw the marginal & here is it 5mm? (slide No#30 the
right pic.) No, so i change the bar into a plate ( the left pic.).
- How do I measure the sulcus? Do I measure it while p't in
Of course Not, we measure it during the functional movement ,
because the depth of the sulcus change from resting to fnx , it
become much shorter. We will lose around 1cm from the depth.
This is done inside the p't mouth , i can't use the cast to measure
this distance and said this distance from here to there is enough!!
☠ a contraindication of this that when we have a shallow
sulcus we can't put a lingual bar, another C.I: about placing a bar in
the anterior teeth going inwards, they are tilted lingualy , so I can't
put a bar in ,we can't also change it into a plate, so i have to think
about sth else (slide #31).
☲ so the lingual plate could act like a major connector , and a
The lingual plate is placed from down up to 3mm above the
marginal gingiva , we make a relief beneath it , good polished , and
No beading cause it's cross the gingiva.
(slide# 34) This is usually where the lingual bar located : beneath
the teeth , & there is sth beneath the bar that's the green in color (in
the slide) which is the relief material , cause we want the bar not to
be close to the tissue to prevent traumatized it .
Also it located on the alveolar ridge , suppose that i want to place it
beneath the tongue, it's a bar connecting he parts of the denture ,
but i want to place it under the tongue in the movable area, I'm
avoiding the most movable area and replacing it under beneath the
tongue , we call it Sublingual bar .
(slide # 36) This is a metal not relief , where the spikes of the metal
going in the embrasures btw the teeth causing trauma to the p't ,
because we didn't do a relief . So make sure you are doing a relief
before doing the metal constructing to the gingiva.
(slide # 36 the right pic. ) Here in this case we don't have enough
clearance , we didn't go away from the gingiva about 6mm , it
begins like inflammation , later on it will proceeds in sth more sever.
✘ another classification called: The continuous Kennedy Bar :
It consist of two bars , one beneath the tooth , and the other one the
tooth which is a very small bar.
It has some disadvantages :
❶ The p't couldn't speak correctly.
❷ It isn't esthetics.
➌ We can't use it in a shallow sulcus.
➍ Can't used it when the teeth tilted lingualy.
✿✿✿ Treatment options:
What are our treatment options? What type should i use?
I have to answer the following questions first:
❶ Do I have enough space for a lingual bar?
❷ Has the p't have a denture previously?
-he could used to use a plate and he didn't want to change it into a
➌ what sort of connector?
➍ spacing btw the anterior teeth , is there is space?
➎ lingualy inclined teeth.
➏ Mandibular tori , can i use a bar when i have a tori ?
The Mandibular tori as a bony prominent that covered by a thin
mucosa , so can i cover it by any of the connector? If it's very minor
i could relief it , but if it's major I have to go to surgery . Another
solution is a swing denture ( we are going to talk about it later).
✆ finally we are going to talk about The Minor connector
It is any metals joining other component to the major connector.
(slide # 40 ) this minor connector is called : Rest , hw it's joining to
the major connector? By a minor connector.
The Minor connector could be act as a reciprocating element.
- How we joining this clasp with the rest?
- By a minor connector , and also by joining the clasp to the major
connector by a minor connector.
- So the Minor connector is a metal projection :
✲ joining components together, they also should be thick enough to
tolerate the forces.
❣ They should be located 5mm from any other vertical components.
Btw 2 minor connector an area should be 5mm. Why? For clinsing
- away from the marginal gingiva 6mm.
- Away from any other vertical component 5mm.
♨ They go up in a right angle.
♒ They go up in a right angle , but it will end in around way to join
the major connector.
✉ We have to have a relief area under it.
✈ They are highly polished.
... a5eeran 5l9t :D ..
Forgive me for any mistakes, & It's pleasure to serving you :D ..
Done by : Zahraa A.Ali Al-hammali