Transcript Basing materials (materials used to protect pulp): role

Pulp Protection:Liners,Varnishes &
Bases
DR Ramesh Bharti
Assistant Professor
Conservative Dentistry & Endodontics
FODS, KGMU,Lucknow
Objectives:
Cavity preparation is relationship with pulp
Explain the protecting the pulp with cavity
Describe the purpose of using cavity liners,
list the type of materials that can be used
and explain the placement procedure
Describe the purpose of using cement base.
List types of materials and placement
procedure
Introduction:
Should be familiar preparation of the cavity
with the amount of enamel and dentin
removed and how near the preparation is to
the pulp
Should understand the pulp protection
theory that the depth of cavity preparations
and pulpal relation
Cavity preparation/Pulp
protection theory
The cavity preparation for a restoration
depends on the amount of decay, the
location of the decay, and the type of
materials used to restore the tooth
Should examine the cavity preparation to
assess pulpal involvement and then place
the liners, base, or warnish
Treatment of cavity preparations
1. Treatment of the ideal cavity preparation
2. Treatment of the beyond – ideal cavity
preparation
3. Treatment of the near – exposure cavity
preparation
Treatment of the ideal cavity
preparation:
A base is not required because only a minimal
amount of enamel and dentin has been removed
Some dentists place only the restoration, while
other prefer to place a fluoride –releasing liner
If an amalgam restoration is going to be placed,
two thin layers of cavity varnish are often placed
over the dentin
If a composite restoration is going to be used, a
glass ionomer liner or calcium hydroxide is placed
over the exposed dentin
Treatment of the beyond – ideal
cavity preparation
With a beyond –ideal preparation , the
level of the dentin is restored with a
cement base
With an amalgam restoration, there are
several options. One option is to placetwo
thin layers of varnish to seal the dentin
tubules and then place a layer of a cement
base, such as zinc phosphate
Another option is a reinforced ZOE base
which has a soothing effect on the pulp.
Varnish is not used with this material
Other options include polycarboxylate or
glass ionomer base, which also do not
require varnish
Under composite restorative materials,
use a glass ionomer base or calcium
hydroxide
Treatment of the near – exposure
cavity preparation:
The nearer the cavity preparation comes to the
pulp, the more precautions are needed. There
are also several options of treatment of the nearexposure preparation
Cavity which going to restore with amalgam, a
liner of calcium hydroxide , glass ionomer , or
ZOE is placed first , then a layer of cement base
such as Zinc phosphate, polycarboxylate, or
glass ionomer cements
Another option for amalgam restoration is to
place a liner, then a layer of reinforced ZOE,
polycarboxylate, or glass ionomer cement. This
is then sealed with cavity varnish , although
some dentist do not place cavity varnish
Restore with composite, a liner is placed first,
then place a layer of either polycarboxylate or
glass ionomer cement
A cavity liner is placed on a near exposure, the
procedure is often referred to as an indirect pulp
capping
Treatment of the exposed- pulp
cavity preparation:
In an exposed pulp, should be decided
whether endodontic treatment is indicated
or should save the vitality of the tooth.
If the treatment of choice is to save the
pulp, a procedure called a direct pulp
capping is performed
Cavity liners
Cavity liners are placed in the deepest
portion of the cavity preparation on the
axial walls or pulpal walls
When the liners are hardened, they form
as a cement layer with minimum strength
Liners are protect the pulp from chemical
irritations and also provide a therapeutic
effect to the tooth
Liners are calcium hydroxide, zinc oxide
eugenol, and glass ionomer cement
Liners also called low-strength base
On this direct pulp capping treatment, place the
calcium hydroxide or glass ionomer liner and
then reinforced ZOE as a temporary restoration .
This gives to the dentist time to see whether the
pulp is going to heal
Another treatment involves the placement of a
liner, a layer of ZOE cement, two thin layers of
varnish, and cement base
Some dentist prefer to place a liner and then a
layer of polycarboxylate or glass ionomer
cement base
Placement of cavity liner in
preparation
Cavity varnish
Cavity varnish is used to seal the dentine
tubules to protect acids, saliva and debris
from the pulp
It is used under amalgam restorations to
prevent microleakageand under zinc
phosphate cement to prevent penetration
of acid to the pulp
If cavity liners or medicated based are
used,varnish is placed after or on top of
these materials
Placement of cavity varnish
Cement bases
Cement bases are mixed to a thick putty
and placed in the cavity to protect the pulp
and provide mechanical support for the
restoration
These cement bases are placed on the
floor of the cavity
Cement bases are glass ionomers, hybrid
ionomers, reinforced zinc oxide
Placement of cement bases
Mineral Trioxide Aggregate(MTA)
Composition
* MTA is mainly composed of 3 powder ingredients,
which are 75% Portland cement, 20% bismuth oxide,
5% gypsum; lime (CaO), silica (SiO2) & bismuth oxide
(Bi2O3) are the 3 main oxides in the cement.
* Portland cement is the major constituent. It is
responsible for the setting & biologic properties.
* Bismuth oxide provides radiopacity.
* Gypsum is an important determinant of setting time.
Portland cement is composed of 4 major components;
tricalcium silicate, dicalcium silicate, tricalcium
aluminate, & tetracalcium aluminoferrite.
• Tricalcium silicate is the most important constituent of
Portland cement. It is the major component in the
formation of calcium silicate hydrate which gives early
strength to Portland cement.
* Dicalcium silicate hydrates more slowly than tricalcium
silicate & is responsiple for the latter’s strength.
* Aluminoferrite (contains iron) is present in gray MTA. It
is responsible for the gray discoloration. It may
discolor the tooth.
Types of MTA
Gray MTA (GMTA) and White
1. Contains aluminoferrite (contains iron), which is responsible
for the gray discoloration. It discolors both the tooth &
gingival tissue close to the repaired root surface.
4. Produces 43% more surface hydroxyapatite crystals than
WMTA in an environment with PBS (phosphate- buffered
saline).
5. Induced dentin formation more efficiently; high number of
dentin bridge formation (reparative dentin).
White MTA (WMTA)
1. Tooth-colored, due to lower amounts of Fe2O3.
2. Smaller particles with narrower size distribution (8
times smaller than that of GMTA).
3. Greater compressive strength.
MTA
Manipulation
Mixing: gray MTA & white MTA are mixed with supplied
sterile water in a powder to liquid ratio of 3:1 according
to the manufacturer’s instruction.
Note: Poor handling properties. The loose sandy nature of
the mixture causes much difficulty for the insertion &
packing of MTA.
Uses
1)Apexogenesis, direct pulp capping and pulpotomy.
2)Apexification, and root-end filling.
3)Repair of root perforations.
4)Repair of internal and external resorption
Advantages
1) Save treatment time. High success rate. It is the material of
choice for apexification & apexogenesis.
2) Alkaline pH, which may impart antibacterial effect on some
facultative bacteria.
3) Can induce formation (regeneration) of dentin, cementum,
bone & periodontal ligament.
4) Excellent biocompatibility and appropriate mechanical
properties.
5) Excellent sealing ability.
6) Produces an artificial barrier, against which an obturating
material can be condensed.
7) Hardens (sets) in the presence of moisture.
8) More radiopaque than Ca(OH)2.
9) Vasoconstrictive. This could be beneficial for hemostasis
(most importantly in pulp capping
Disadvantages
1)Long setting time (2-4 h after mixing).
2)Poor handling properties. The loose sandy nature
of the mixture causes much difficulty for insertion &
packing of MTA.
3)High cost