2. Compound and Complex Cavities
On Posterior Teeth
**Notes from the doctor about our Performance in the clinics :
1-Write your notes on the file (eg:LA was given ,class I cavity
preparation on (# of tooth), lining was place ,and cavity was filled
with amalgam or composite or whatever )
2- Is student suppose to treat painful tooth ? NO (Don’t try to
treat painful teeth because it's not purpose of your clinics ,The
purpose is to train you to become competed dentists in the future
.
3- What cases do a student select ? (go through your
requirements)
4-Upper hand for your supervisor of the clinic (Don’t rely on
what's written in the Diagnostic sheet )
_____________________________________
** PIC (Refer to slide please) series of handpieces :
All of these handpieces are:**
- Slow speed type
- marked with different bands; if you look here there is a band
and a band and two bands
*selection of low speed hand pieces angle :
From the left :contra angle used for most procedures , the second
called increasing handpiece, the third one called ratio speed(
reducing handpiece): used for drilling pins.
3. *every band indicates a speed and a use ,so there are many
types of hand pieces.
PIC: high speed hand piece.-
PIC: straight hand piece.-
you learn about class I ,II ,III ,IV,V , and how ideally prepare
a good cavity , fill it with different materials ,but that’s not all the
time like this ,sometime as a clinician you are faced with cases
ake place onand these tComplexCompound or eventhat is
anterior or on posterior teeth.
Preventive Resin Restoration :
Its used for conservative treatment occurs on an isolated pits
and fissures and spontaneous caries prevention in the
remaining an affected pits and fissures.
For example: U have got a patient with a tooth let's suppose it's a
molar and it has one pit in a fissure, there is a transverse ridge
and on the opposite side of this ridge there is another pit what do
you do ?
-I will drill the first pit and the second pit and just fill them.
What do I do for the fissure? – fissure sealant .
So what call it now? - PRR.
Indication of PRR :*
rther carries in theevent fuprI'am going to:Preventive1.
fissure system.
.composite and fissure sealentResin :.2
4. .: fillingRestoration3.
How do I do PRR ?
-Using a small bur : remove carries from isolated pits and
fissures .
- No attempt should be made to incorporate retention in to the
preparation, why ?
Because we are using resin ;resin doesn’t need mechanical
retention:
It needs acid etching.-
- Perform Prophylaxis of occlusal surface .
place a thin layer of dentine bonding agent .-
-apply fissure sealant over restored area or adjacent fissure .
It’s a simple case :)
Conventional class II cavity
*Class II got two places where we drill(Pic1)
Box: on the proximal surfaces.
Dove Tail or occlusal extension.
Outline form (refer to the slide) : star shape
Purposes of two extensions: for retention and what
Are their advantages?
1-Elimnated the fissure which is vulnerable to dental
carries .
2-Prevent amalgam from dislodge out( proximally
),again for retention the base of extension should be
5. smaller than the opening ,so if you try to pull the
amalgam in an outward direction ,the amalgam will be
resisted from being removed .
<<The base should be wider than the opening>>
Pic 2 : This is a case with weak marginal ridge ,, in
which I am not sure whether to break this ridge or not ?
what do I do ?
-I will excavate all the caries and properly
eliminate the fissure .
-I have to decide whether to break this marginal
ridge or leave it in place ; the idea is to have a marginal
ridge that is supported by enough dentine underneath ; if
this margin ridge is not supported by enough dentine
then the answer is to cut it.
Modified class II cavity preparation :
A proximal slot preparation.-
Tunnel preparation.-
Conservative class II Resin Restoration.-
A proximal slot preparation :
-It's indicated when the occlusal pits and fissure are
carries free and the carious lesion is accessed via the
buccul or lingual surfaces.
If you access the lesion either from the buccul or the
lingual surface we call it : a proximal slot
preparation .
6. Sometimes we have class II , maybe it's showing from
the buccul surface, you don't have to cut from occlusal
surface ; you can access the lesion from the buccul
surface then you keep the marginal ridge intact , how
do I fill it? I fill it from the buccul access .
The aim here is to keep the marginal ridge
intact
Tunnel preparation :
It means tunneling through from occlusal surface leaving
marginal ridge intact; The idea is keeping the marginal
ridge intact because the marginal ridge is intact ,it's
free of dental carries and its supported by enough
dentine ,if three conditions are met in the marginal
ridge then you are not suppose to cut the margin
ridge (Pic 3).
Look at this building here. There is a hole; a hole is
supported by a pillar here a pillar there, there will be
no problem if you remove the wall between the pillar
But removing the pillar will weaken the building.
Here between this pillar and this pillar there is another
pillar which is in a transverse direction , I want you
to look at the tooth especially the molar , I want you
to look at the molar as a building that composed of
pillars ; one pillar is the cusp , look at the occlusal
surface : you'll see four cusps; these are the four
pillars of the tooth .
Now connection of these pillars: they are connected to
each other by means of a transverse pillars which is
like bridge and the transverse pillars are what? They
are the marginal ridges.
7. Now sometimes you find a transverse ridge that is
DIAGONAL ; it comes from a pillar to another
pillar it's the oblique ridge.
-No building can stand any forces without these pillars
.
-There is no problem if you remove one of the walls ,
as you can see that you can cut in the wall to form a
window or to make a dove ( there is no problem)
But if you cut a pillar ; there is a big problem !!! you
are weakening the building and in our case you are
weakening the tooth.
So the aim is to keep the configuration of the
tooth intact as much as you can
-if you remove a part of an architecture of the tooth
and you disturb the configuration then you have to
restore it by certain means.
Conservative class II Resin Restoration :
- If a lesion is small but has weakened marginal
ridge a small cavity is cut and restored with
composite.
- if you do conventional amalgam restoration , what
are you doing then ?
**You are deeping it ,making retention,making
the base wider than the opening .
-you want retentive groove .
-any time you cut ,cut, cut ,you are weakening the
tooth .
-there is an invention in dentistry called composite
;this composite is good enough in small cases because
there is no much stress bearing-area over there.
so simple: acid etch the small area and then
place a good composite restoration.
So look what we have done actually
8. 1*the approximal slot and Tunnel we maintained
the marginal ridge intact.
2*conservative class II restoration we kept it small
because maybe there is carious and the next dentist
will remove this composite and will add a new
composite.
-Every time we cut a tooth ,we are increasing the
cavity by 0.6 mm of (*** 35:46 ) .
-Cavities are repeated:
cavities are getting bigger ,filling are getting bigger
,the architecture of the tooth is damaged ,so
we have actually to make it small all the time
.
**Refer to slide >> show you a caries in a
proximal surface..
This is Premolar and this is a molar;Its class II:
1.you can access the lesion from buccul side .
2.use excavator to excavate the caries.
3.put simple matrix band .
4. fill it with a suitable resin restoration .
How do I do the tunnel ?
The concept of tunnel preparation is simple:
**minimal enamel and dentine removal
compatible with caries elimination .
-the caries is very small; it has to be a small lesion,
you don’t do tunnel preparation for a large lesion.
Indication of Tunnel preparation :**
-small lesion on a proximal surface1
2-occlusal pits and fissures are either carious or
vulnerable to dental caries; how?--> (very
deep) .
9. Refer to Slide : pic 4 :
which is simple class II cavity !
I don’t you to make a huge cavity, make it simple .
-Here is the access , I suppose that there is a
lesion on proximal surface what do I do ?
*I get the access underneath marginal ridge to
remove the caries ( Initial access for the
tunnel).
-if you look at this diagram (refer to slide) you will
see tunnel preparation : It's like T; this is the
circle which is called O-access (pic5) , you
actually get the bur in the middle going
underneath the marginal ridge.
How wide marginal ridge should be ?
At least 2 mm underneath marginal ridge so that
will get free access in the region ,you need an
element of t-like access in the tunnel preparation
so that you can get your bur move in a buccul and
lingual direction .
done by ahmad khasati
*Modified Preparation :
10. - the good about modified preparation is that it’s
conservative ( marginal ridge stays , and cusps stays
strong ) and conventional cavity still can be prepared ( if
the marginal ridge broke for example) .
- the bad(drawbacks) it’s difficult to prepare and tilt ..
* you can go from modified to conventional preparation ,
but not the opposite ..
MO : miso occlusal caries .
DO : disto occlusal careis.
MOD : miso occlusal disto caries .
In the maxillary molars: if the oblique ridge is intact (it' is
supported well by dentine) you can do a two separated cavities
class II cavities from each side not opened to each other.
In MOD preparation :you can fill it with amalgam safely , WHY?
because you haven’t loss any cusp ; you only loss walls ( mesial
wall , distal wall , occlusal wall ) .
when two adjacent walls are missing there is a problem.
* here we have lose a corner with pillars so we do what’s called “
amalgam bullied up “ or “ core bullied up “ by using an
extra ridge for retention.
Here when I lose corners adjacent to walls so I need extra aids of
retention so I can’t get conventional retention so what do I
do ?
I need ( I couldn't hear 45:33)
How do I gain retention for such cases?
11. -here I can have weaken cusps :extensive caries , repeated
amalgam replacement and recurrent caies.
so when more than one cusp is to be replaced , we need
additional retention by :
1.intracorner coronal retentive features , such as :
A.amalgam pins .
B.slots.
C.occlusal steps.
D.box preparation .
E.cleat holes.
1: amalgam pins :
*we use it when we lose all of the cusps and want to bullied up
the teeth by amalgam only .
* so we prepare 4 holes and condense amalgam inside these
holes.
*those holes are acting like pins .
>>They are not the pins which you use in extra retention but pins
made of amalgam itself<<
*the chambers are cut parallel to the tooth surface , the
margins are beveled , (0.5 _ 1mm) from amelodentinal junction
and the diameter is about (0.8 mm ) inside the dentine .
12. why we want to go (0.5 _1 ) from ameleodentinal junction ?
**to avoid the Periodontal ligaments and not to get close to the
pulp .
2:slots :
They are essentially a cross cut in the sound tissue (0.5 -1
mm ) from the amelodentinal junction and it’s made
segments or continuous on it’s all length by cutting
grooves and making it retentive .
-refer to the slide : A slot
B slot
so if you condense amalgam here , the grooves will give the
retention ( mechanical preparation ).
<<the base of the groove should be wider than the
opening of it >>
a round bur is used to groom the conventional floor of
the box and number (??49:55) bur is used through
the lingual cusp; grooves should be sufficiently deep
to offer some resistance .
this tooth doesn't have retention and what you are
doing here Is cutting the grooves and the grooves are
made retentive.
>>note : additional retention are different than
conventional retention<<
**if the question was in the exam : how do I retain
amalgam ? we are talking here about conventional
13. retention !!
3:Box preparation :
* means that there is no occlusal retention .
*only box preparation in the proximal surfaces.
*box in the buccal or palate extension on the molar of
posterior teeth and we can achieve retention by making the box
occlusaly convergent .
*Now if all these additional means of retention aren’t achievable
>>>what to do?
The answer is to use pins .
we drill inside the dentine and we put the pin .
** So when there is a loss of 2 walls and more and we can't
make groove or slots we use pins to get additional retention
.
Now when a patient come to you with a heavily carious teeth or
broken cusp so what we should do with walls >>first we make
excavation for the walls after we do enough excavation now
-anything that is supported with dentine we will leave it .
-if its thin remove it .
-if it supported with sound dentine reduce it to 2 mm.
Before we put the pin we should asses the teeth by taking a
radiograph so we can see where to put the pin .
Remember sometimes the x-ray can be misleading; Why?
because we are transferring a 3D veiw to a 2D veiw ,which is
the film.
14. -let's say you have a lesion on the buccal surface and you take an
x-ray, the lesion will be superimposed on the pulp Or if we have
an amalgam filling on the buccal surface and we direct the beam,
it will appear superimposed on the top of the pulp .
*We have 3 types of pins:
1-cemmented pins (we cemented it inside the tooth to get
additional retention)
2-frictional locked pins (this isn’t cemented we make a hole in
the dentine and then we put it in >>>>because the dentine is
resilient when we put a pin inside the dentine it will grip it firmly )
3- self threded pins (it is screwed in: like when we want to
insert a screw inside a piece of wood. here the dentine is the wood
and the pin is the screw .it means as the pin go inside the dentine
its threading its self a space inside the dentin)
**1/2 length of the pin inside the amalgam and other1/2
should be inside the dentine.
*So what are the rules of the pins:
1-never insert a pin inside the enamel because its brittle.
so if you try to put a pin inside the amelodentinal junction, the
enamel will chip away from dentine because there is no chemical
union between enamel and dentine (scalloped)
2-never insert in the pulp.
3-never insert in the PDL .
4-it should be (1 mm) a way from the amelodentinal junction
5-1 pin on each corner (in every place where the cusp has
chipped—maximum 4 pins)
15. 6-when we use a matrix band with the pin we don’t remove it
immediately because the amalgam need 24 hours to set so after
1 day we remove the band and do polishing and finishing.
_**Complication of using pins :
--It can easily perforate the PDL and the pulp .
Now if the pin wasn’t useful what is the next step ?
we use post it means :
- enter the canal and take extra aid of retention by either
ready made post or cast post (post retain crowns )
***Examples:
1-para post
2-chartel post
*the canal should be treated before we put a post inside
it *
*The distal canal of the lower and the palatal canal of
the upper because they are the largest canal*
Done by : Amr Sadi and Hasan Al Balwa
