Transcript PIT AND FISSURE SEALANTS

PIT AND FISSURE
SEALANTS
DEFINITION
According to Simonsen Pit and Fissure
Sealants are
“A material that is introduced into the pits and fissures
of caries susceptible teeth, thus forming a
micromechanically bonded, protective layer cutting
access of caries producing bacteria from their source
of nutrients.”
• Fissure sealants are defined whereby
pits and fissures that occur
principally on the occlusal surfaces of
molar and premolar teeth are
occluded by application of fluid
materials which are then
polymerized.
HISTORY
• 1905- Miller used silver nitrate
• 1922- Hyatt advocated prophylactic odontomy.
• 1939- Gore used solution of cellulose nitrate as fissure
sealants.
• 1955- Buonocore observed that after treatment of
enamel with H3PO4 the retention of acrylic resin to
tooth surface was greatly increased.
• 1965- Bomen developed Bis-GMA
• 1971- First pit and fissure sealant Nurva seal
developed.
Morphology of Pits and
Fissures
• The fissure contains organic plug
composed of reduced enamel epithelium,
micro-organism forming dental plaque and
oral debris.
• The increased susceptibility of this
surface to caries is due to the fact that
fissure provides a protected niche for
plaque accumulation.
• There are 5 types of pits and
fissures:
V -type (34%)
U-type (14%)
I- type (19%)
K- type (26%)
Inverted y - type (7%)
Histopathology of Pit and
Fissure Caries
• First evidence of lesion formation
occurs at orifice of the fissure and is
represented by two bilateral lesion in
enamel on opposing cuspal inclines.
• Lesion progresses and depth of
fissure wall becomes involved.
• Two lesions coalesce into one at base
of fissure.
• The enamel at the base is affected and
lesion spreads laterally along the enamel
adjacent to the depth of fissure towards
DEJ.
• Cavitation occurs owing to loss of mineral
and structural support from affected
enamel and dentin resulting in the clinically
detectable lesion.
Types of Pit and Fissure
Sealants :1. According to chemical structures
of monomer used
2. Based on generation
3. Based on filler contents
4. Based on Color
5. Based on curing
1.
•
•
•
•
•
•
According to chemical structures of
monomer used:
MMA Methyl methacrylate
TEGDMA - Tri ethylene glycol
dimethacrylate
BPD Bis Phenol dimethacrylate
BISGMA - Bis Phenol A and Glycedyl
Methacrylate with methyl
methacrylate monomer.
ESPE Monomer
PMU Propyl methacrylate
urethane
2.Based on generation:
a) 1st Gen - Ultraviolet light.
But had excessive absorption and incomplete
polymerisation of sealant at its depth.
b)
2nd Gen - Self cure or chemical cure
based on accelerator catalyst system.
c) 3rd Gen - Visible light
d) 4th Gen - Fluoride Releasing Sealants.
3.Based on filler contents:
a) Unfilled - AD - Better flow a retention
DisAD - ABRADE Rapidly.
b) Filled - AD - Resistance to wear
DisAD - Needs occlusal adjustment
4. Based on Color :
a) Clear -Esthetic but difficult to
detect
b) Tinted / opaque - can be identified
c) Colored - Easy to see placement and
recall
5. Based on curing :
a) Autopolymerizing
b) Light cure
INDICATIONS
• Clinical judgment is the deciding factor in the
placement of sealants.
• Newly erupted both primary molars and
permanent biouspids and molars with complete
recession of pericoronal operculum with open and
sticky grooves and fissures.
• Stained pits and fissures with minimum
decalcification or opacification and no softness at
base of fissures.
• The tooth in question should have erupted need
that 4 years ago.
CONTRAINDICATIONS
• Individual with no previous caries
experience and well coalesced pit and
fissures. Monitor if the individual and
teeth not at risk.
• Radiographic or clinical evidence of caries
on proximal surface should not be sealed.
• Wide and self cleansable pit and fissures.
• Tooth that cant be isolated or partially
erupted.
• Pit and fissure that have remained carious
free for 4 years or longer.
TECHNIQUE FOR
PLACEMENT OF PIT AND
FISSURE SEALANT
Step 1 :
Isolation of Tooth
The tooth should be isolated from salivary contamination by
use of rubber dam or by cotton rolls and suctioning.
Step 2 :
Tooth Preparation
Different methods
- Early concept was to treat the surface with sherry of
pumice and water.
- Brockleherst suggests :
Air abrasion with aluminum oxide.
Best method of cleaning as results improved surface of
resin wetting, more no of resin tag formation and more
depth of sealant peneteration.
Step 3 :
Acid Etching Tooth Surface
Occlusal surface is then etched with 30-50%
H3PO4 (37%) liquid or gel for 60 seconds.
Etching produces microscopic porosities in the
channel. Resin extends in these microscopic
porosities and forms tags with attach it firmly to
tooth surface.
With different
etch times, no quantitative differences
in surface morphology
of enamel are observed.
Step
Primary teeth
Permanent teeth
Acid wash
30 sec
20 sec
Wash
30 sec
30 sec
Dry
15 sec
15 sec
Step 4: Rinse and Dry Etched Tooth Surface
Rinse the etched tooth surface with air water
spray for 30 second.
- After etching tooth surface should remain
dry and free of any contaminants.
- If surface becomes contaminated re-etched
for additional 10 sec.
Step 5: Application of Bonding Agent
Application of bonding agent after etching
displaces saliva from enamel.
Strength Increases
- Saliva contaminated enamel
(0.0005 mpa to 17.8 mpa)
- Uncontaminated enamel
(16.7 mpa to 20.5 mpa)
Step 6 :
Application of Sealant
Apply material and allow it to flow into pits and
fissures.
Avoid Incorporating air bubbles.
Step 7 :
Curing
Material is cured according to manufacturers
direction.
Step 8 :
Evaluation of occlusion
Step 9 :
Re-call and Re-evaluation
Recall and check in subsequent visits.
- It is still formally adherent.
- no sealant material has been lost (if necessary,
material should be added at this time.)
COMPOSITE RESINS
Introduction
Apart from the glass ionomers, the only other
material that has the ability to restore
aesthetics and to develop and maintain
adhesion in the oral environment is the
composite resin. However their ability to
adhere long term to tooth structure is limited
to enamel only.
History
1930s
First mention of the
methyl methacrylates.
Kramer and
McLean
1949
Published several
papers on a number of
material in this category.
Buonocore
1954
Development of a micro
mechanical adhesion to
enamel simply by acid
etching the enamel for
up to one minute rather
than applying a thin coat
of a very low viscosity
resin.
1960s
Proved the value of
including a variety of
fillers.
Late
Bowen
Bowen’s contribution
Apart from proving the value of fillers
Bowen also modified the resin
formula from a relatively simple
methyl methacrylate to a far more
complex bisphenol-A diglycidyl
dimethacrylate and the modern
concept of 'filled' or 'composite
resin' was generated.
Based on filler particle size and
size distribution- Lutz and Philips
(1983)
Type 1: macro filled composite resin
Type 2: micro filled composite resin
Type 3: hybrid composite resin
Type 1: macro filled composite resin
This type is also known as conventional or traditional composites.
. Because of the relatively large particle size this group exhibits a pattern
of unacceptable wear both of itself and of the opposing tooth.
Type 2: micro filled composite resin
The fillers in this material are amorphous silica particles of 0.04 mm
average diameter. With such small filler particles they are translucent
and highly aesthetic but high filler loading is difficult to achieve. The
wear resistance is low and they cannot sustain in high filler loading.
Type 3: hybrid composite resin
These are also known as small particle composites. They contain a
combination of macrofiller particles with a proportion of microfiller
particles and are probably the most commonly used composite resins.
The main variation is in the proportion and distribution of the various
particle sizes because this will control the ability to fill the resin and
increase the percentage loading.
Constituents
The chemistry and setting reaction of
a composite resin is very complex
so there are a number of different
chemical and materials
incorporated, each with a specific
function and the proportion is likely
to vary from one manufacturer to
another.
- An organic resin component that forms the matrix
e.g. BisGMA
- Inorganic filler: These may be
a. Macro fillers with a particle size of about 5-30
mm e.g. glass, quartz, ceramic etc.
b. Micro fillers with a particle size of 0.04 mm e.g.
amorphous silica.
- Coupling agent applied to the particles to unite the
filler to the resin silane.
- Initiator system to activate the setting mechanism.
- Stabilisers (inhibitors)
- Pigments (colouring agents)
Variations in composite resins





Based upon the forgoing information there
have been further variation developed in the
composite resin range based largely upon
the filler particles and their size distribution.
Folwable
Packable
Chemical activated
Light activated
Others
Flowable

The term flowable has been developed to
indicate a composite resin which is relatively
simple to place into a cavity in contrast to the
standard hybrid materials which can be
rather stiff and possibly a bit sticky. Such a
flowable material is manly used in the case
of a deciduous tooth. The flowability of the
composite resin is improved by reducing the
filler content.
Packable

Another term has been introduced to differentiate a
material from a standard hybrid composite resin and
that is the term packable. the difference is achieved
by varying the particle size and size distribution
though the water uptake and the wear factor will
remain standard and acceptable. The main
difference will be in the feel of the material when
being placed into the cavity. The material will be less
likely to stick to the packing instrument and be
withdrawn from the cavity during placement.
Chemically activated systems

These materials are marketed as two paste
or powder / liquid systems. One part will
contain an initiator, benzoyl peroxide, the
other part contains a tertiary aromatic amine
accelerator and combination of two parts will
yield free radicals. These radicals initiate
polymerisation of the resin.
Visible light activated systems

Single paste, visible light activated composite resin
systems contain a two component initiator system
comprising a di-ketone and a tertiary amine. The
photosensitive di-ketone, usually 0.2-0.7%
camphoroquinone, absorbs the radiant energy of
wavelength approximately 470 nm. At the
appropriate stage of excitation, the di-ketone
combine with the amine to form a complex that
breaks down to release free radicals that then initiate
polymerisation of the resin.
Other systems

Dual activated composites have both a light
activated and a chemically activated initiation
system and are packaged as two pastes. The
light activation mechanism is used to initiate
polymerization and the chemical activation is
relied upon to continue and complete the
setting reaction.
Properties of Composite Resins
Polymerization
The actual chemistry of the setting reaction is
reasonably complex but is typical of all resin
polymerization. In a chemically activated composite
resin, the reaction takes place almost uniformly
throughout the bulk of the material. In the light
activated systems, the depth to which activation will
occur is dependent on a number of factors. It is
important to note that much of the resin not activated
initially by the light at the time of curing will remain
unset.

Water sorption and solubility
Water sorption is higher for micro filled resins and for
hybrid and macrofilled resins. A minimum amount of
water sorption is essential to a newly placed
composite resin because it will bring about a degree
of expansion and help to counteract setting reaction.
Variation in the water sorption and solubility of
different composite resin is associated with the type
and amount of monomers.

Polymerization contraction
The resin matrix in a composite resin is highly
subject to a setting contraction whether it is
light activated or auto cured. The problems
and risk are less in restoring deciduous teeth
because the cavities are relatively small and
it is therefore somewhat easier to get light
activation to penetrate the relatively short
distance to the base of the restoration.

Wear
Clinical wear of the composite resin remains one of the main
weaknesses in its use as restoration on load bearing
surfaces.
Regardless of the material, clinical wear is associated with a
roughening of the surface of the restoration, due in part to
scratching of microfilled composites and partly due to loss
of particles and frictional contact in the case of macro filled
composites. The slightly greater resistance to wear of a
heavily filled micro filled composite is consistent with the
greater resistance to sliding wear shown by this material.
Therefore it is desirable to use the most heavily filled
material availing regardless of possible difficulty in clinical
handling.

Etching and bonding

An essential prerequisite for the micro - mechanical
attachment is that the enamel should be etched with
37% orthophosphoric acid to deminerablize the
enamel to a depth of 20 to 30 um and render it
porous. A very low viscosity unfilled resin is then
flowed over the surface and allowed to soak in to the
porosities for about 30 seconds before it is light
activated. Composite resin is then built over the resin
bond.
Prerequisites for etching


The enamel at the cavity margin must be fully
mineralized and soundly based on healthy
dentin. Also there must be no micro cracks
present on the tooth.
The best union will be developed at the ends
of the enamel rods rather than along the long
sides so it is desirable to develop a
reasonably long bevel at the cavo-surface
margin.

The goal of a resin dentin bonding agent is to attach composite
resin to healthy dentin and to seal the dentin tubules against
the entry of bacteria and their toxins.

This will avoid post restoration sensitivity caries and loss of
restoration.

Bonding to dentin requires the removal of all deminerlized
affected dentin and this is not always desirable, particularly in a
deciduous tooth where there will be little enough dentin
remaining above the pulp and an exposure is undesirable.

It is possible through the use of glass ionomer to remineralize
some of the dentin and this is the preferred method of sealing a
cavity in a deciduous tooth.
Principles to successful resin - dentin
bonding
- Dentin should be etched to remove smear
layer and dentin tubule plugs.
- Etching should be sufficient to demineralize
the surface layer of both inter and
intratubular dentin leaving collagen fibers
exposed and available for a mechanical
interlock with the resin.
- The surface should be thoroughly washed to
remove all remaining etchant.
- The surface should remain wet but not
flooded.
- Apply a hydrophilic primer containing
acetone or similar to guide and facilitate
penetration of the resin adhesive around the
exposed collagen fibers.
- Finally apply the resin adhesive and cure
before applying composite resin.
Delivery and placement


The chemical cure and the dual cure materials will
be packaged as a paste / paste system or a powder /
liquid system. Always follow the manufacturer’s
instructions in detail and stay within the time
parameters so as not to go beyond the working time.
To ensure complete adaptation to the cavity floor it is
desirable to place the freshly mixed material into the
disposable syringe and then tamp the material into
the cavity with a small plastic sponge.


The light activated materials will always be delivered
in light proof carpules or syringes which have been
loaded under vacuum. This means that they are free
of porosity at the time of delivery.
Placement must be undertaken with care and
attention to detail with particular reference to the
depth of cure available through a curing light. The
efficiency of the light must be checked periodically to
ensure that the lower layers are also cured
adequately.
Incremental build up

Due to the problems posed by light activation of
composite resins, it is essential to be prepared to
undertake incremental build up of any restoration
deeper that about 2.0 mm. Incremental placement
means placement of the composite in small
quantities in selected areas of the cavity and then
directing the light activating unit in such a way that,
while curing, the resin will shrink towards the tooth
structure rather than away from it.
Depth of cure

In view of the often limited access to the oral
environment in a child patient the depth of cure of a
composite resin is quite significant. It is imperative
that the activator light be placed within 1-2 mm of the
surface of the newly placed restoration otherwise the
depth of cure will be limited.

Failure to light activate the composite resin to the full
depth of the restoration has important implications
for the success and longevity of the restoration.
Factors to be considered while curing




The degree of cure will decrease with increasing
depth.
Increased time to exposure to the light will
increase depth of cure.
The more heavily filled the resin and the larger the
particle size, the greater depth of cure. Micro filled
resins will cure to a depth of 2-3 mm only while
hybrid resins may cure to a depth of 4-5 mm.
Lighter the shade of material the greater the depth
of cure and the greater the translucency the deeper
the cure.




Light activator units vary in their light outputs over
time as well as with power fluctuations. The
efficiency of each unit should be checked frequently.
The tip of the light source should be placed as close
as possible to the restoration and should never be
more than 4 mm away.
The depth of cure should be measured from the face
of the activator light.
Curing through tooth structure will reduce the depth
of cure to the same extent as if curing through a
composite resin of similar opacity.
Limitations of composite resins



Both the resin and the fillers used are anhydrous
and completely inert. However some of the minor
constituents such as HEMA have been identified as
allergens and pose a potential risk.
Any unreacted polymer chains may be an irritant
to the pulp and lead to post - insertion sensitivity.
The tissue cells respond les favorably to
composite resin than they do to glass ionomer and it
has been postulated that incomplete cure of the
resin is the prime cause of this.
Clinical considerations

In pediatric dentistry a restoration will not be expected to last for
more than a few years so a limited amount of wear can be
tolerated. However a relatively large setting shrinkage will be
undesirable. Aeshtetics and fracture resistance will not be of great
significance but the ability to bond effectively to both the enamel
and dentin will be relevant. There will often be a relatively short
concentration span from the patient as well as limited access to the
oral cavity so simplicity of placement techniques will be important.
There is often a clear choice between composite resin and glass
ionomer and the operator must be aware of the relevant properties
of both so that a logical decision can be made.
Prepared By :Dr.Ronak Shrimal
B.D.S.,MHA,MSOLA
MIDA,MIAACD