PIT-AND-FISSURE SEALANTS

Prof.d-r R.Kabaktchieva- 2014

PREVENTIVE SEALING OF THE FISSURES - KINDS OF SEALANTS.

DIFFERENTIAL DIAGNOSIS BETWEEN DEEP SOUND FISSURES AND DENTAL CARIES. INDICATIONS AND CONTRAINDICATION FOR SEALANT APPLICATION IN PRIMARY AND PERMANENT TEETH. METHODS.

REMINERALIZATION AS A METHOD FOR PRIMARY CARIES PREVENTION. CONTEMPORARY MEDICATIONS AND METHODS.

 

Fluorides are highly effective in reducing the number of carious lesions occurring on the smooth surfaces of enamel and cementum.

Fluorides are not equally effective in protecting the occlusal pits and fissures, where the majority of carious lesions occur.

This results in an increased proportion in the ratio of occlusal to interproximal lesions,

even though the total number may be less.

In the late 1960s and early 1970s, another option became available - the use of pit-and-fissure sealants.

A liquid resin, more commonly called a dental sealant.

The placement of sealants is a highly effective means of preventing carious lesions

in the pits and fissures in both primary and permanent teeth.

Dental sealant is placed over the occlusal surface of the tooth, where it penetrates the deep fissures to fill areas that cannot be cleaned with the toothbrush.

1. One reason that 50% of the carious lesions occur on the occlusal surface

is that the toothbrush bristle has a greater diameter than the width of the fissure. - the fissure cannot be cleaned with the toothbrush.

The resin then solidifies;

The hardened sealant presents a barrier between the tooth and the hostile oral environment.

Concurrently, there is a significant reduction of Streptococcus mutans on the treated tooth surface.

Pits and fissures serve as reservoirs for mutans streptococci;

Therefore, sealing the niche reduces their oral count.

Sealants present great preventive value when placed correctly and monitored regularly.

Sealant Use in Dental Care

The first successful use of resin sealants was reported by Buonocore in the 1960s.

Buonocore first described placing sealants, using a method to bond polymethyl-methacrylate (PMMA) to human enamel conditioned with phosphoric acid.

This concept, was realized later, after the development of :

- bisphenol A-glycidyl methylacrylate

(Bis-GMA),

- urethane dimethacrylate (UDMA),

- triethylene glycol dimethacrylate

(TEGDMA) resins. They possessed better physical properties than PMMA.

Bisphenol A-glycidyl methylacrylate is a mixture of Bis-GMA and methyl methacrylate;

Nuva-Seal, the first successful commercial sealant, was placed on the market in 1972;

Since then, more effective sealants have

become available;

The primary difference between sealants is

the method of polymerization

Some sealants contain fillers.

The products was classified like filled and unfilled sealants.

The filled sealants contain microscopic glass beads, quartz particles, and other fillers used in composite resins.

The fillers are coated with products such as silane to facilitate their combination with the Bis-GMA resin.

The fillers make the sealant more resistant to abrasion and wear.

Because filled sealants are more resistant to abrasion, the occlusion should be checked, and the sealant height may need to be adjusted after placement.

The unfilled sealants wear quicker but usually do not need occlusal adjustment.

Criteria for Selecting Teeth for Sealant Placement

A deep occlusal fissure, fossa, or incisal lingual pit is present.

No harm can occur from sealing, when in doubt, seal and monitor.

A sealant is indicated if:

The fossa (shallow depression) selected for sealant placement is well isolated from another fossa with a restoration.

The area selected is confined to a fully erupted fossa, even though the distal fossa is impossible to seal because of inadequate eruption.

The selected tooth has an intact occlusal surface when the contralateral tooth surface (surface of tooth in opposite arch) is carious or restored; teeth on opposite sides of the arches usually are equally prone to caries.

An incipient lesion exists in the pit-and-fissure area.

Sealant material can be flowed over a conservative class I composite or amalgam to improve the marginal integrity,

and into the remaining pits and fissures to further prevent recurrent decay.

A. Five years after placement of a white pit-and-fissure sealant - tooth M1

B. 5-year control: The first permanent molar in other side has been restored with two amalgam restorations

C. 15-year sealant: 15 years after the single application of a white pit-and-fissure sealant - the same tooth as in A., but 10 years later.

As can be seen, the sealant has served its purpose , but there has been some loss in the peripheral fissures.

a b c

All teeth meeting the previous criteria should be sealed and re-sealed as needed.

Sealants should be placed on the teeth of children and adults if there is evidence of existing or impending caries susceptibility

Other Considerations in Tooth Selection

Аges 3 and 4 years (preschool) are the most important times for sealing the eligible deciduous teeth;

Ages 6 to 7 years - for the first permanent molars;

Ages 11 to 13 years - for the second permanent molars and premolars.

The disease susceptibility of the tooth should be considered

when selecting teeth for sealants, not the age of the individual.

Evaluating of occlusal risk

Rely on professional judgment, based on the severity of the caries activity indicators:

- number of "sticky" fissures,

- level of plaque index,

- number of incipient and overt lesions,

- microbiologic test indications.

Combining sealant placement and

regular fluoride exposure would save many school days, dental treatment and

would achieve better dental health.

A sealant is contraindicated if: Patient behavior does not permit use of adequate

dry-field techniques throughout the procedure.

An open, frank, carious lesion exists on the same tooth.

Caries exist on other surfaces of the same tooth in which restoration will disrupt an intact sealant.

A large occlusal restoration is already present.

Polymerization of Sealants

The common sealant is a liquid resin called a monomer (a molecule that can be bound to similar molecules to form a polymer, which contains two or more monomers).

When the catalyst acts on the monomer, repeating chemical bonds begin to form, as the hardening process - polymerization proceeds .

Finally, the resultant hard product is known as a polymer.

Two methods have been used to catalyze polymerization

The first method is light curing with the use of a visible blue light,

Тhe light-cured sealants contain a catalyst, such as camphoroquinone, which is placed in the monomer .

The catalyst is sensitive and when the monomer is exposed to the visible blue light, polymerization is initiated.

The second method is self-curing,

in which a monomer and a catalyst are

mixed together to induce polymerization without the use of a light source;

synonyms for this process are cold cure, autopolymerization, and chemical activation.

In first-generation sealants, polymerization was initiated by

ultraviolet light;

Second-generation sealants were autopolymerized,

Third-generation sealants used visible blue light.

Fourth- and fifth-generation sealants added a step in which

dental-bonding agents were used as a primer before the sealants were placed.

Sixth-generation sealants use a self-etching process.

Less frequently, glass ionomer cement is used as a dental sealant.

Light-emitting diode (LED) curing unit for direct, intraoral exposure.

Types of SealantsGlass Ionomer Cement Sealants

Glass ionomer cements have been used as dental sealants.

Тhey do not have the same effective retention rates as those of conventional sealants.

Fluoride-Releasing Sealants

Because fluoride uptake increases

the enamel's resistance to caries,

the use of a fluoridated resin-based sealant may provide an additional anticariogenic effect if the fluoride released is incorporated into the adjacent enamel.

Fluoride is added to sealants by two methods:

The first is by adding a soluble fluoride to the unpolymerized resin.

The fluoride can be expected to leach

out over a period of time into the adjacent enamel.

Eventually the fluoride content of the

sealant should be exhausted, but the content of the enamel greatly

increased.

The second method of incorporating fluoride is by the addition of an organic fluoride compound that is chemically bound to the resin to form an ion exchange resin.

When fluoride is low in the saliva, fluoride would be released,

When the fluoride in the environment is high, it should bind to the resin to form a reservoir for fluoride release and recharge.

Fluoride-releasing sealants have shown antibacterial properties as well as a greater artificial caries resistance compared with a non-fluoridated sealant.

Fluoridated sealants have also demonstrated a caries-inhibiting effect, with a significant reduction in lesion depth in adjacent surface enamel and a reduction in the frequency of wall lesions.

However, recent reviews revealed that, compared with resin-based sealants, fluoride-containing sealants have a poor retention rate after 48 months; they also have not proven to act as a fluoride reservoir with long-term release of fluoride into the oral environment.

Colored Versus Clear Sealants

Both clear and colored sealants are available.

They vary from translucent to white, yellow,

and pink.

The colored products permit a more precise placement of the sealant.

Retention can be more accurately monitored by both the patient and the operator placing the sealant.

Some clinicians prefer the clear sealants, because it is possible to see under the sealant to detect if a carious lesion is active or advancing.

Requisites for Sealant Retention

For sealant retention the surface of the tooth must

(1) have a maximum surface area, (2) have deep, irregular pits and fissures, (3) be clean, (4) be absolutely dry at the time of sealant

placement and uncontaminated with saliva residue.

Increasing the Surface Area

Sealants do not bond directly to the teeth.

They are retained mainly by adhesive

forces.

To increase the surface area,

which in turn increases the adhesive potential, tooth conditioners (also called etchants), which are composed of a 30 to 50% concentration of phosphoric acid, are placed on the occlusal surface prior to the placement of the sealant.

The etchant may be either in liquid or gel form. The gel is easier to apply and easier to

remove.

Tooth after etchant is placed.

When a tooth is etched, it appears chalky white .

Pit-and-Fissure Depth

Deep, irregular pits and fissures offer a much more favorable surface contour for sealant retention compared with broad, shallow fossae.

An electron-scanning microscope view of the deep pits and fissures of the occlusal surface of a molar.

Тhe possibility of caries development

is increased when the fissure depth and slope of the inclined planes is increased

Thus, as the potential for caries increases, so does the potential for sealant retention.

Surface cleaning

Тhe cleaning preferences either by acid etching or other methods - all stains, deposits, debris, and plaque should be removed from the occlusal surface before applying the sealant.

Usually the acid etching alone is sufficient for surface cleaning.

Other methods used to clean the tooth surface prior to placing the sealant included,

- air-polishing,

- use of hydrogen peroxide, - polishing with pumice, - brushing with a non-fluoridated toothpaste, - use of laser.

The use of an air-polisher has proven to thoroughly clean and removes residual debris from pits and fissures.

Hydrogen peroxide has the disadvantage that it produces a precipitate on the enamel surface.

Comparison of acid etching with laser alone did not demonstrate any significant difference of sealant retention or microleakage.

Cleaning teeth with the newer prophylaxis pastes with or without fluoride (NuPro, Topex) was not shown to affect the bond strength of sealants.

Simonsen accomplished the most effective sealant longevity without use of a prior prophylaxis.

Cleaning the tooth surface with oil-free pumice is recommended for sixth-generation sealant material.

Sealant Retention Resin sealants are retained better on recently

erupted teeth than on teeth with a more mature surface. !!!!!

They are retained better on first molars than on second molars, and are better retained on mandibular than on maxillary teeth.

The mandibular teeth being more accessible and easier to see; also, gravity aids the flow of the sealant into the fissures.

Sealants appear to be equally retained on occlusal surfaces in primary and permanent teeth.

When the resin sealant flows over the prepared surface, it penetrates the finger-like depressions created by the etching solution.

These projections of resin into the etched areas are called tags

The tags are essential for retention.

 

Tags, 30 micron.

If sealants are lost, the teeth should be resealed.

Over the first 3 months, the rapid loss of sealants is probably caused by faulty technique in placement.

Pit-and-fissure sealants applied during childhood have a long-lasting, caries-preventive effect.

Teeth successfully sealed for 6 to 7 years are likely to remain sealed.

Preparing the Tooth for Sealant Application

After the selected teeth are isolated, they are thoroughly dried for approximately 10 seconds.

The liquid etchant is then placed on the tooth with a small sponge or cotton. Аcid gels are applied with a syringe

Тhe etching solution is gently daubed, not rubbed, on the surface for 1 minute for permanent teeth and for 11/2 minutes for deciduous teeth.

Аcid etching the enamel of both primary and permanent teeth for only 20 seconds produced similar sealant retention.

For 10 seconds the water is flowed over the occlusal surface .

Following the water flush, the tooth surface is dried for 10 seconds.

The dried tooth surface should have a white, dull, frosty appearance.

Тhe surface area is greatly increased by the acid etch.

Dryness The teeth must be dry at the time of sealant

placement because sealants are hydrophobic.

The presence of saliva on the tooth is even more detrimental than water because its organic components interpose a barrier between the tooth and the sealant.

Sealant placement. A. Gel etchant is applied to teeth, B. Etched surface has a "frosty" appearance. C. Application of resin-based sealant.

Application of the Sealant Тhe material should first be placed in the fissures where

there is the maximum depth.

The sealant should not only fill the fissures but should have some bulk over the fissure.

After the fissures are adequately covered, approximately halfway up the inclined plane is covered too.

Following polymerization, If any voids are evident, additional sealant can be added without the need for any additional etching.

All the commercial sealants - both the light-cured and self-cured are of the same Bis-GMA chemical family, they easily bond to one another.

Occlusal and Interproximal Discrepancies

An excess of sealant may be flowed into a fossa or into the interproximal spaces.

Тhe occlusion should be checked with articulating paper.

If the premature contact of the occlusal contact is unacceptable, a large, round cutting bur may be used to rapidly create a broad resin fossa.

Тhe interproximal spaces can be checked with the use of dental floss.

Evaluating Retention of Sealants

The finished sealant should be checked for retention .

In the event that the sealant does not adhere, the placement procedures should be repeated, with only about 15 seconds of etching needed to remove the residual saliva before again flushing, drying, and applying the sealant.

If two attempts are unsuccessful, the sealant application should be postponed until remineralization occurs.

Teeth that have been sealed and then have lost the sealant have had fewer lesions than control teeth.

This is possibly due to the presence of tags that are retained in the enamel after the bulk of the sealant has been lost from the tooth surface.

Over the first 3 months, the rapid loss of sealants is probably caused by faulty technique in placement.

After a year or so, the sealants become very difficult to see or to discern tactilely, especially if they are abraded to the point that they fill only the fissures.

Because the most rapid falloff of sealants occurs in the early stages, an initial 3-month recall following placement should be routine for determining if sealants have been lost. If so, the teeth should be resealed.

Teeth successfully sealed for 6 to 7 years are likely to remain sealed.

Тhe pit-and-fissure sealants applied during childhood have a long-lasting, caries preventive effect.

Where resealing is accomplished as needed at recall appointments,

a higher and more continuous level of protection is achieved.

Sealants Versus Amalgams

When properly placed, sealants are no temporary expedient for prevention;

They are the only effective predictable clinical procedure available for preventing occlusal caries.

The most frequent cause for sealant replacement is loss of material, which mainly occurs during the first 6 months;

To replace the sealant, only resealing is necessary. No damage occurs to the tooth.

The sealant has the advantage of being painless to apply and aesthetic,

The sealants have the highest objectives of the

dental profession - prevention of sound teeth.

Options for Protecting the Occlusal Surfaces

Several options are now available to protect the occlusal surfaces,

with the selection depending on risk and professional's judgment.

The first level of protection is simply

to place a conventional sealant over the occlusal fissure system.

This sealing protect future pit-and-fissure caries, as well as arrests incipient or reverses small overt lesions.

The second option reported by Simonsen in 1978) advocated the use of the smallest bur to remove the carious material from the bottom of a pit or fissure and then using an appropriate instrument to apply either sealant or composite into the cavity preparation.

This he termed a preventive dentistry restoration.

Following insertion of the restoration, sealant was placed over the polymerized material as well as flowed over the remaining fissure system.

Aside from protecting the fissures from future caries, it also protects the composite from abrasion.

The third option is use of glass-ionomers material for sealants, which is controversial.

Due to their fluoride release and cariostatic

effect, glass-ionomers have been used in place of traditional materials, as a pit-and-fissure sealant,

However, resin sealants have shown much higher bond strength to enamel than glass-ionomers.

A fourth option reported by Garcia-Godoy in 1986 involves the use of a glass-ionomer cement as the preventive glass-ionomer restoration (PGIR).

The glass-ionomer cement (conventional or resin-modified) is placed only in the cavity preparation.

The occlusal surface is then etched with a gel etchant avoiding, if possible, etching the glass-ionomer.

The conventional resin sealant is placed over the glass-ionomer and the entire occlusal fissure system.

In the event sealant is lost, the fluoride content of the glass-ionomer helps prevent future primary and secondary caries formation

"This combination of preventive techniques (combined use of fluoride and sealants) is expected to essentially eliminate caries in teeth erupting”

In Bulgaria the dental profession have accepted sealants as a routine method for prevention.

De and remineralisation Demineralization is caused by plaque

acids, which dissolve the tooth minerals making up the basic calcium, phosphate, and hydroxyl crystals of the enamel, dentin, and cementum.

Remineralization, requires the availability of the same ions, preferably with fluoride as a catalyst to reconstruct the missing or damaged rods,

This process Ten Cate calls non-restorative repair.

Have shown that products containing amorphous calcium phosphate (ACP) can stimulate remineralization of tooth enamel.

Products containing ACP, or ingredients that form ACP, can be found in:

- toothpastes, - mouthrinses, - artificial saliva, - chewing gums, - topically applied coatings, - other vehicles for topical use.

The crystals and fluoride compound

of most dental products, interest in the demineralization and remineralization process are:

- hydroxyapatite (HAP),

- fluorhydroxyapatite (FHA),

- calcium fluoride (CaF2).

The long-term exposure of teeth

to low concentrations of fluoride

(as found in fluoridated water)

results in the gradual incorporation of fluoride into the existing hydroxyapatite (HAP) crystals

to form fluorhydroxyapatite (FHA), which is more resistant to acid damage.

Conversely, a higher concentration of fluoride (as occurs with the use of topical fluoride applications - fluoride dentifrices, foams, and varnishes)

results in the formation of surface globules of CaF2 .

If phosphates and proteins of the saliva coat these globules, the globules become more insoluble.

When the fluoride is incorporated into HAP (hydroxyapatite crystals) to form FHA (fluorhydroxyapatite ), it is said to be firmly bound,

while, loosely bound fluoride is in the form of CaF2, which is adsorbed onto the surface of HAP and FHA crystals.

The Relationship between HAP, FHA, and CaF2

After an attack by plaque acid(s),

CaF2 dissolves first,

followed in sequence by HAP,

and finally, FHA (with its fluoride substitutions).

As the attack continues, the dissociated ions increase the saturation level of the immediate fluid sufficiently

to slow crystal dissolution and eventually arrest further solution of the crystals.

As the pH begins to return to normal, crystals begin to re-form from the complex pool of dissolved ions,

- some as HAP,

- some as FHA (with many of the fluoride ions coming from the previous CaF2).

Finally, newly adsorbed CaF2 is precipitated.

Any defects are subsequently replaced, in time, by calcium, phosphate, and fluoride

from sources such as the saliva, water, and toothpastes.

CaF2 provides a reservoir for fluoride that is immediately available when and where it is needed.

The only time the system breaks down is when the attacks are too frequent and too prolonged.

Depth of Remineralization

There is little controversy about the success of topical procedures in stimulating surface remineralization,

and of the use of commercial fluoride products such a dentifrices, gels, and varnish to compensate for the daily wear and tear of demineralization.

An in vitro study performed by Тen Cate showed that оnly the outer part of the enamel appeared to be responsive to fluoride diffusion and remineralization.

The test for remineralization in these cases is the lack of demonstrable caries progress for 2 to 3 years.

Modern re/mineralising agents

In recent years, had the effect of

several new agents with unique qualities.

These are:

- amorphous calcium phosphate (ACP),

- casein phosphopeptides (CPP).

Means of remineralization based on amorphous calcium phosphate

Remineralizing action has proven two-phase system of Ca and P in toothpaste under the brand name of "Enamel Care Toothpaste" with producer Arm & Hammer Enamel Care.

With this paste provides mixing of the two phases adjacent to the enamel surface, wherein the ions respond to the amorphous calcium phosphate precipitating the enamel.

Because the amorphous calcium phosphate is highly soluble in all acidic attack, it is rapidly released Ca and P.

Kazeinfosfopeptids (CPP) and amorphous calcium phosphate (ACP)

Australian Eric Rejnolds opened a new phenomenon of the interaction between amorphous calcium phosphate and milk proteins.

Products are:

Tooth mousse, MI paste

end