3 Filling Materials for Permanent and Temporary Seals

8/12/2019 3 Filling Materials for Permanent and Temporary Seals

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Classification of filling materials

There are several classification of filling materials.

Depending to which group the tooth belongs, fillingmaterials are distinguished:

For front group of teeth( filling materials shouldcorrespond to high esthetic requirements);

For molars and premolars (filling materials shouldstand high occlusion press)


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1. Metals : amalgam, alloys, pure metals (gold);

2. Non metals: cements, plastic, composite materials.

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According to the material from what restorative materials

are produced, they are divided into:


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Filling materials are divided for:

Temporary fillings; Permanent fillings; Curative linings; Isolative linings; Sealing for the root canal.

According to the purpose


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Separate group of filling materials consist from adhesives,sealants, varnishes. Its not filling materials, but dentist cantwork without them.

From the point of view of functionality and peculiarities oftheir usage in the clinic, all filling materials are divided into 2

groups: 1. Restorative(should provide complete restoration of the

shape of the tooth, and also renew the function of the toothfor long time);

2. Curative-prophylaxis (should have good curative-prophylaxis qualities).


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Several factors have to be taken into account when choosing the most

appropriate restorative method and material for a clinical situation. The

limiting factors include:

Patient motivation and suitability.

The number of remaining teeth and their relative positions.

The condition of their supporting tissues.

The amount of remaining tooth structure.

The restorative materials available, and their longevity as restoratives. The occlusion and opposing teeth and restorations.

Aesthetic and other wishes of the patient, including cost factors.

Direct restoratives: clinical properties, handling and

placement


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The direct restoratives in current, general use areamalgam, composite, glass - ionomer cements andcombinations of the last two groups

Available materials


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Dental amalgam is a mixture of mercury and an alloy

containing silver and tin with added copper and zinc. The alloyand mercury are held together in a capsule, with the twocomponents separated by a plastic diaphragm. When thediaphragm is broken and the capsule is placed in the mixingmachine (amalgamator), the two components are mixed

together (triturated) to form a silver-coloured paste. Thispaste is then condensed into the cavity. This is a veryimportant stage: well-condensed amalgams are stronger thanpoorly condensed ones, as more of the weaker, mercury-rich2-phase is removed during carving. Amalgam is weak in thinsection so cavities have to be cut suitably deep (2 mm) andbecause amalgam does not adhere to tooth tissue, the cavitymust be undercut.

Dental amalgam


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Resin composites used in dentistry have severalcomponents:

Resin matrix: commonly a fluid monomer, Bis-GMA.

Filler particles of silica-based glass. Silane: an agent that allows the resin and filler

particles to bond together.

Activator for the setting reaction: normally

camphorquinone. Pigments.

Resin composites


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Direct resin composites are the material of choice for

anterior restorations and they are increasing in use

and popularity for posterior restorations, mainly becauseof their appearance. Composites

do not adhere directly to tooth

tissue and rely on the acid-etch

technique and the use of dental

adhesives for adhesion to

enamel and dentine.


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Light curing of resin composites is initiated by light inthe wavelength range 450500 nm. This blue light

can damage the eyes so an orange filter should beused when the light is in use. The tip of the lightsource should be placed as close as possible to thesurface of the restoration and each increment ofcomposite should be cured for 4060 seconds.Under-cured composites will readily absorb stain andwill rapidly degenerate.

Light curing


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Polymerisation shrinkage of the resin during curing (in the

order of 23%) still occurs and may contribute to marginaldefects, cuspal distortion and crack formation in the enamelor dentine, and may therefore contribute to postoperativepain or sensitivity for the patient. There are, however, anumber of clinical techniques available to overcome theseproblems and the longevity of restorations using the newerresin composites is much improved over that of the originalmaterials.


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Diagram showing incremental placement ofresin composite


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Reducing the effect of polymerisation shrinkage maybe achieved by incremental packing of the

composite. Each increment should touch as few wallsof the cavity as possible . The stress induced bypolymerization shrinkage is highest in cavities withmore bonded than unbonded surfaces: the occlusalcavity has the potential for the most stress.


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Deep subgingival preparations.

Lack of peripheral enamel. Poor moisture control.

Load-bearing cusps.

Resin composites are not suitable in the

following clinical situations:


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Glass ionomers contain poly(alkenoic) acid and fluoro-aluminosilicate glass which set by an acidbase reaction togive a cement.

They adhere directly to tooth substance and to base metalcasting alloys.

They release fluoride after placement, giving the materialscariostatic properties, although this may only be short term.

Glass ionomers


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They also have a low tensile strength which makes thembrittle and unsuitable for use in load-bearing areas in

permanent teeth.

They are used as lining and luting materials and to restoreabrasion and erosion lesions, cervical lesions and deciduous

(primary) teeth and as interim restorations.

It must be appreciated, however, that they are lesstranslucent than resin composite restoratives and therefore

their appearance is less acceptable.


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Resin-modified glass ionomers have a resin (monomer)component as well as the poly(alkenoic) acid and fluoro-

aluminosilicate glass of conventional glass ionomers. They set by two mechanisms: acidbase reaction and curing

of the monomer (chemically, by light or both).

They have improved appearance and physical properties

compared with conventional glass ionomers. They are used in similar situations to glass ionomers and

may also be used for small core build-ups.

Resin-modified glass ionomers


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Polyacid modified resin composites are also known ascompomers.

Their properties are more like those of composites thanglass ionomers.

They have limited fluoride release but are stronger and havea better appearance than glass ionomers.

Their wear resistance is less than that of compositerestoratives.

They do not adhere directly to tooth substance without the

use of a bonding system. They may be utillised to restore cervical and anterior

proximal cavities and for primary teeth.

Polyacid modified resin composites


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Acid etching with phosphoric acid creates poreswithin the enamel into which resin flows to createtags.

This micromechanical retention is very reliable unlessthere has been contamination of the etched surfaceby saliva or blood.

This technique is used to retain fissure sealants,composite restorations, orthodontic brackets, resin-retained bridges, veneers and other tooth-colouredrestorations.

Acid etching


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There is some merit in etching preparations prior toplacing a sealer, liner or base, as etching will

remove the smear layer which is contaminated withbacteria. Removal of the smear layer in this wayaffords gross debridement of the preparation andwill also improve the quality of the interface

between the sealer/liner and the dentine substrate.


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Bonding to dentine is more difficult than bondingto enamel as, unlike enamel, dentine containswater and has a greater proportion of organicmaterial.

Bonding to dentine may be achieved reliably withcurrent systems which involve between one andthree steps and which either remove or modify thesmear layer (this is a layer of debris created by

cutting through dentine).

The bond to dentine is a combination of chemicaland micromechanical bonding.

Dental adhesives


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Current systems are

classified as follows:

Total etch (or etch and rinse):

3 step comprising etch, prime and bond. 2 step etch followed by a single application of primer

mixed with bond.

Self etch:

2 step etch and prime step, followed by bond. 1 step etch, prime and bond in a single application.


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To prevent noxious stimuli reaching the pulp it has beencustom and practice to apply protective materials to the

floor and/or the pulpo-axial wall of preparations. These materials were commonly placed

under amalgams and resin composites

to prevent thermal stimulation of the

pulp and acid contamination of

dentine.

Linings for pulp protection


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Preparation liners also seal freshly cut dentine but have

additional functions, such as adhesion to toothstructure, fluoride release and/or antibacterial action.

Preparation liners are applied in thin section (


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Temporary restorative materials and their

placement


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Temporary restorations are placed for the

following reasons:

To improve patient comfort by:

Preventing sensitivity.

Preventing food packing.

Restoring appearance.

Covering sharp margins of a cavity.


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To provide a sedative effect on an infllamed pulp.

As an interim restoration before placing the final

restoration; perhaps to allow improvement ingingival condition or to assess the patients responseto diet and oral health advice.

As a planned procedure prior to placing alaboratory-made restoration.


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To assess the prognosis of the tooth and/or pulp.

To prevent drifting, over-eruption, tilting or gingivalovergrowth.

For caries prevention: by using a fluoride leachingmaterial, such as glass ionomer.


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How long the temporary restoration is to be in

place: this depends on the wear characteristics of thematerial used.

The choice of eventual restoration: eugenolplasticizes composite resin restoratives so there is arisk that any eugenol remaining from the temporaryrestoration could adversely affect a subsequent

composite resin restoration, although recentresearch suggests this is not a problem.


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The ideal temporary material should be easy and

quick to mix, place and shape. It should set quicklyand have appropriate strength and wear

characteristics.

The material used should be non-toxic and be non-

irritant to the pulp, preferably with a sedativeeffect on the pulp.

Ideal temporary material


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It should also have an acceptable colour, taste and

smell and be cheap and readily available.

It is essential that it is easy to remove and is

compatible with other materials.


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This depends on:The size and shape of the cavity: a self-adhesivematerial such as a glass ionomer may be required ifthe cavity has no inherent retentive form.

The position in the mouth: tooth-coloured materialshould be used for anterior teeth. Stronger materials

should be used for the occlusal surfaces of posteriorteeth.

Choice of material


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Zinc oxide eugenol based materials: these are quickand easy to insert and remove, but are unaesthetic,

lack compressive strength and the taste is sometimesconsidered unpleasant.

Polycarboxylates.

Glass ionomers.Light-cured polymers.

Available materials


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3 Filling Materials for Permanent and Temporary Seals

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