DM Lec #8 By Leen

View previous topic View next topic Go down

DM Lec #8 By Leen

Post by Sura on 5/12/2011, 2:36 am

avatar
Sura

عدد المساهمات : 484
النشاط : 2
تاريخ التسجيل : 2010-09-29

Back to top Go down

Re: DM Lec #8 By Leen

Post by Shadi Jarrar on 23/12/2011, 7:11 pm

بسم الله الرحمن الرحيم
Lec 8 dental materials
Dr.mohamad Hamad
Date of lec.13-11-2011
Endodontic Materials

Root canal obturation materials
Obturation is the second step of RCT ;after cleaning and shaping
In this lec we are going to talk about gutta percha,sealers and some old materials used in RC obturation and some new materials.
The material we use upstairs is gutta percha solid cores with sealer
Ideal properties of root canal filling materials:
-antimicrobial
-biocompatible
-good flow like sealer enter properly in spaces
-adhesive in nature; makes bonding and this is very important since u cannot sterilize the canal ,u want to prevent the fluids and nutrient to enter to the bacteria ,so u prevent oral fluids and nutrients from entering the canal and prevent apical fluid from penetrating the filling which is called (perculation)
-Dimensionally stable ,doesn’t shrink bcs if we used a material which is liquid and when it dries it shrinks then we will have gaps and voids then leakage will occur which we don’t want.
Not affected by moisture; doesn’t dissolve-
-Radio opaque to show in x-ray to know how successful your work is
-Good handling ,there are some materials which are really difficult to handle ie,working time is very shork,very hard mixing.
-Easily removed if I wanted to put a post,or to redo the treatment if not successful so I cannot use MTA( cement al buna) bcs it can't be removed
Does not stain dentine -
Cheap-
Gutta percha
Is a plant and it is the oldest(100YRS ago) and most common filing material,it is a natural rubber material (latex) taken from trees.natural rubber and gutta percha have the same chemical composition which is C5H8 but they are different in structure so they are isomers.
So polymers of isoprene:
Cis is natural rubber-
Trans is the gutta percha-
Gutta percha cone is composed of:
20% only gutta percha
60-75%zinc oxide
And metal sulphides,waxes,resin and opacifiers.
Every company have a secret ingredient which differs from other companies but we know 98% of it.
Gutta percha actually is available in 3 phases alpha,beta and gamma but in dentistry we have alpha and beta only,when they cut the tree a semisolid material will flow which is the alpha phase, the beta phase is what we use in clinics which is solid cones we can interchange between alpha and beta by heating so alpha phase is flowable(not liquid) but beta phase is hard, we in our clinics as we use the lateral condensation technique so we use the beta phase, but specialists use the alpha phase as they do the thermoplastic obturation .
In the volume and phase change chart on slide no.6 we can see beta phase and if u put the temp. above 40c it would be flowable alpha phase and if u raise it more it would be amorphous phase (which is above 60 c,and in this phase the gutta percha cannot be shaped and is not usable anymore).
Advantages of gutta percha:

1.biocompatible
Actually it is very very biocompatible
2.dimensionally stable
Neither expands nor shrinks
3.compactable
4.easily removed
5.cheap
Disadvantages:
1.doesnt adhere to dentine
In theory If I have a material which can adhere to the tooth structure first I will decrease the micro leakage or make it zero and second I will strengthen the root (bcs endo treated teeth are prone to fracture due to cutting of the dentino-enamel), make it resistant to fracture.
2.lacks rigidity it can bend easily specially size 15,20 that’s why we don’t use these sizes a lot.
Metal points
Before gutta percha they used to use metal points and the most famous of these metal points are the silver points,they enter the canal they make very minimal cleaning and shaping so the canal stays very narrow without curvature then they put the metal point then they close it ,it is rigid ,antibacterial but the problem that they use to depend on cement to close the spaces ,we will have corrosion ,and microleakage.
They used to use it in 60s and 70s but.It is not used any more,u might see it if u treat an old patient who has done endo treatment before 20 or 30 years ago,if u want to retreat it is very difficult to remove.
It is very radioopague and very rigid
Sealers
The sealer makes lubrication for the canal and the second thing it closes the small gaps that the gutta percha cant close, unfortunately we in our clinics use a lot of sealer to close gaps but that is wrong we have to use extremely minimal sealer, bcs if sealer was that good so why don’t we fill the whole canal with sealer? So we shouldn’t depend on sealer in filling the canal. So why do we use sealer:
1.cementing the core material which is the gutta percha into the canal.
2.filling the discrepancies btwn the canal walls and core material.
3.acting as lubricant to enhance the positioning of the core material.
4.acting as a bactericidal agent if we have a sealer that kills bacteria its perfect.
We have five families of sealers and most of them have these properties:
- toxic when freshly mixed and toxicity reduced or diminish when sets ,so toxicity is when we mix is very high.
-most sealers are absorbable to some extent when exposed to tissue fluid, for example if I did an excellent filling with a kind of sealer and everything was perfect then tissue fluids go in the apex and start to dissolve the sealer ,the patient come one year later and u see there is no filling material at the apex, fluids will enter and make reinfection,so the ideal qualities of sealer is that they are not absorbed or dissolved with body fluids.
The families of sealers are:
1.zinc oxide eugenol
is like calcium hydroxide one of the universal materials in dentistry u find it in prostho ,cons and endo.
Most common trade names are Grossmans and Tubliseal
It is antibacterial
Radio opaque , good flow
Slightly toxic when freshly mixed like other sealers
The problem is that it doesn’t adhere so it doesn’t strengthen the tooth and it is soluble so after 1-2 years it will dissolve from the apex so the goal of our work will go, but anyway it is still used.
Q,don’t we suppose to make the gutta percha reach the apex?
Yes but the problem is that some doctors they don’t do tug-back so not all doc. Follow the book
2.calcium hydroxide based sealers
Trade names Sealapex ,Apexit
Radio opaque
Soluble
Biocompatible
Antimicrobial
The problem is that it doesn’t adhere to the tooth structure and has high solubility so lots of doc stopped using this material.
3. Resin based sealers
These materials were introduced to deal with the adherence problems so it is adhesive.
We put the sealer with resin material to make the adhesion just like in cons.
Trade names AH26,AH plus, Endorez ,Epiphany, Realseal. The last three are new materials introduced before 3-4 yrs.
What is the sealer we use in dispensary????
The problem with this material and all resin materials is the shrinkage.
antibacterial ,toxic when freshly mixed.
4.Glass ionomer based sealers
Ketac Endo stopped in 2005, Active GP sealer 2007-2009
Mildly antibacterial
Adheres
Slightly soluble
The problem is that it is very difficult to be removed.
The active GP system was introduced in America in 2007 it is made of gutta percha cones with glass ionomer particles
and the sealer itself is made of glass ionomer then the sealer adhere with the cones from one side and the walls from the other side , not widely used bcs it is very difficult to be removed.
5.Silicone based sealers
Roekoseal sealer (Germany),why do u thing they put silicone?
Bcs it can expand and in this way if there was a small gap it will close then after setting the filling would be better than before setting.
it slightly expands when sets 0.2% i.e. 2-10%(this what the doc said) which is not much but useful
there is a system called GuttaFlow which is Roekoseal sealer(made of silicon) but gutta percha particles is added to it.
GuttaFlow as shown in the pic. Is capsules mixed in the amalgamator for 30 scnds then we get flowable cold gutta percha (not hot) then we inject this material in the root canal with one cone(the master cone which closes the apex) and that’s it.
The problem of this material that it doesn’t adhere to root canal.
It makes expansion
NEW root canal filling materials
Resilon is a material introduced in 2004 in America,the main material in it is polycaprolacton this material is used a lot in medicine it is very biocompatible ,the sealer used with this material is resin based sealer (epiphany or realseal) then we put the resilon cones with epiphany sealer or realseal then that all binned together with the dentine of the root canal and forms (wehda waheda) called monoblock, in theory if we get a material that forms one block with the tooth structure under pressure this is called monoblock but that is still a theory.
Note from Q. this the same as glass ionomer but that is called uniblock
Endorez cones:by ultradent company ,it is resin coated gutta percha used with endorez sealer or any other resin based sealer. Then core join sealer and sealer joins with dentin to form a monoblock.
Activ GP :glass ionomer coated gutta percha used with glass ionomer based sealers,same idea as endorez
All endo companies are trying to apply the monoblock theory bcs if they find this material it would be the excellent filling material bcs gutta percha we are using doesn’t form this unit.
Retrograde root filling materials
If a patient come with a swelling on upper central for example and u did rct treatment for him and after a time u see him and the swelling is getting bigger u did him retreatment and then he come again with swelling what can u do for him?
Apecectomy,steps for this procedure as shown in slides:
U do reflexion for the gum to the wall we remove some infected bone(bkoon motaakel)
U cut 3mm from the tip of tooth apex with the gutta percha inside
U cut another 3mm of gutta percha from the canal by an instrument
U close the apex this 3mm ,but what filling can u use?
There are a lot of filling materials but each one has its own disadvantages e.g.
Amalgam…toxicity,fluids and blood in the flap area,microleakage
Modified zinc oxide eugenol(IRM)
Super EBA
Composite…shrinkage,moisture control,microleakage
Glass ionomer cements
MTA………………Mineral Trioxide Aggregate it is the best cement (cement al binaa) but with some modifications add calcifiers and remove toxic materials.
It was introduced by Torbinjad (from Iran) who invented irrigants,some files,books,,,
Advantages:
-perfect microleakage zero microleakage.

-enhance formation of cementogenesis
Enhance formation of new cement
-highly biocompatible
Disadvantages:
-very difficult handling bcs it is cement so u have to add water sometimes
-needs at least 4 hrs to set so I do the procedure put the MTA and send the patient home and do him other appointement .there is other kind called MTA angelous which takes 20 mints to set but not as good quality as MTA.
-very expensive, 1 gram In 50 dollars.
Good luck
Done by:Leen Qutachi
avatar
Shadi Jarrar
مشرف عام

عدد المساهمات : 997
النشاط : 12
تاريخ التسجيل : 2009-08-28
العمر : 26
الموقع : Amman-Jordan

http://jude.my-rpg.com

Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum