Clinical Application

of restorative

materials

Successful results in operative dentistry cannot be achieved without using proper restorative materials.

The final restoration will never be better than the properties of the material selected for its fabrication.

The restoration is expected to perform The restoration is expected to perform certain FUNCTIONS:certain FUNCTIONS:

1. To stop further progress of lesions in hard tissue or loss of these tissues. To prevent future recurrence of caries.

2. To restore and maintain normal interproximal embrasures and contact areas.

3. To establish normal occlusion.

4. To restore and maintain esthetics.

5. To sustain functional forces.

These are:1. Adaptability to cavity walls and margins2. Great strength properties3. Dimensional stability in the cavity4. Biologic compatibility with the adjacent structures

and pulp5. Insolubility in the fluids of the mouth6. Harmonious color7. Low thermal conductivity and thermal changes8. Convenience of manipulation

To achieve these objectives the restorative material To achieve these objectives the restorative material used is required to possessused is required to possess DEFINITE DEFINITE PROPERTIESPROPERTIES..

This refers to the This refers to the degree of proximity to degree of proximity to cavity walls and marginscavity walls and margins that the that the restorative material will be able to restorative material will be able to attain and maintain under oral attain and maintain under oral conditions.conditions.

1. Adaptability to cavity walls and margins

Perfect marginal adaptation and cavity seal by the restoration is essential to prevent …

• The ingress of fluids, bacteria and other irritants from the mouth.

• Post restorative hypersensitivity.• Recurrent caries.• Pulp irritation.• Discoloration of the restoration and the tooth

structure.

The optimum degree of marginal adaptation requires:

that the materials bond chemically with or adhere to tooth substance under oral conditions (stress, moisture and thermal changes).

Maintenance of satisfactory adaptation requires also: that the restorative material have a Coefficient of Thermal Expansion similar to or very close to that of the tooth. Otherwise, the tooth and the restoration will expand and contract differently when subjected to temperature changes leading to Marginal Percolation.

FortunatelyWith the introduction and application of

“ADHESIVE DENTISTRY” the adaptability of the newly developed

“ADHESIVE RESTORATIONS”has improved.

Two adhesive systems have been developed:

• Bonding to enamel can be obtained by:

• ADHESION of a GIC.

• The attachment of a polymer to acid etched enamel.

• Bonding to dentin can be obtained by:

• ADHESION of a GIC.

• The bonding of a polymer containing composite restorative material to dentin, by the use of a chemical coupling agent (primer and adhesive).

The restorative material must have adequate strength against all the types of functional stresses including tensile, compressive, shear and impact, whether these be static or dynamic.

2. GREAT STRENGTH PROPERTIES

• gold is superior to all restoratives.

• ceramic

• amalgam lacks only adequate tensile strength

However …

BOTH gold and amalgam have satisfactory strength

properties.

• Because of the improved strength properties of SMALL PARTICLE AND HYBIRD COMPOSITES, they are suggested for applications in stress-bearing areas such as class IV and class II restorations.

• The restorative formulations of GLASS IONOMER CEMENT (Type II) fail the strength properties and, therefore, are selected for use as an anterior restoration, particularly in non-stress-bearing situations (class III & V).

The restoration must exhibit no dimensional changes in the form of EXPANSION or CONTRACTION after being placed in the cavity whether during setting or due to thermal changes in the mouth.

3. DIMENSIONAL STABILITY IN THE CAVITY

EXPANSION causes marginal overhangs, pressure on dentin and discomfort to the patient. The margins may also protrude and fracture with increased chances for recurrence of caries..

CONTRACTION leads to:

- Marginal seepage

- Irritation of dentin.

- Marginal discoloration.

- Recurrent caries.

- Looseness of the restoration.

• Gold and ceramic per se are the best.

• Amalgam is next.

• Composite and GIC contract on setting.

4. BIOLOGIC COMPATIBILTY WITH THE ADJACENT STRUCTURE AND

PULP

Restorative material must be free from noxious effects on the gingival tissues and the pulp.

The cavity depth is considered to be the most important influencing factor in pulp reaction to irritation by cavity preparation,

or restorative technique and materials.

• Irritation from restorative materials per se may be:

• Thermal or galvanic (metallic restorations)

• Chemical due to:

- Metallic ions from amalgam.Also ...

It may be due to the detrimental ingress of bacteria from the mouth due to inability of the restoration to seal the cavity adequately.

Deep cavities, therefore, must be considered to be like pulp exposures and be lined with a non-irritant material such as calcium hydroxide applied to the floor of the cavity with least pressure.

5. INSOLUBILITY IN THE FLUIDS OF THE MOUTH

The restorative material must be perfectly insoluble in the fluids of the mouth irrespective of its type and pH fluctuations

• Metallic restorative materials, ceramics and composite resins satisfy this requirement.

• Glass ionomer cement fails this property

6. HARMONIOUS COLORTo stimulate the color of the tooth, the restorative material is required to have the combined color of enamel and dentin.

Ceramic, composite resin and GIC or in combination satisfy this requirement to a suitable extent although color changes may take place with time.

Metallic restoratives fail this property.

7. NO CONDUCTIVITY TO THERMAL CHANGES

The restoration may be subjected, even temporarily, to wide ranges of temperature changes. Therefore, it should be nonconductor of heat, otherwise the pulp will be subjected to repeated thermal shocks.Ceramic and non-metallic materials satisfy this requirement.

8. CONVENIENCE OF MANIPULATION

The restorative material must be easy to fabricate without detailed procedures or expensive special equipment.

- Amalgam is the best in this respect.- Composite and GIC come next.- GOLD foil is not easy to condense by the average

operator.- Ceramic needs high skill in fabrication

It seems that we do not have as yet the ideal restorative material which fulfills the required properties. For this reason,

we have to compromise to select the restorative material which is most

suitable for a particular case.

FACTORS INFLUENCING SELECTION

OF THE

RESTORATIVE MATERIAL.

The FACTORS which influence selection of the restorative materials include:

1. The physical properties of the presently available restorative materials.

2. The ability of the restorative material to maintain the physical properties of the tooth.

3. The ability of the restorative material to maintain occlusion

4. The size of the cavity

5. Age, physical condition and mentality of the patient

The FACTORSFACTORS which influence selection of the restorative materials include (cont.)

6. Friability of enamel

7. Sensitivity of dentin

8. Hygienic condition of the mouth

9. Relative caries susceptibility.

10. Esthetics

11. The use of other metallic restorations in the mouth.

12. The question of the fee.

1. The physical properties of the presently available restorative materilas

These physical properties must be thoroughly understood and the influence of the functional performance of the restoration highly appreciated.

2. The ability of the restorative material to maintain the physical property of the tooth

• Gold is the material of choice because it can be used in thin section to protect and reinforce remaining tooth structure, reestablish ideal contour and anatomy, rebuild occlusion with high accuracy.

• Ceramic is the second choice. However, it is too brittle to be designed in thin section and more of the remaining tooth structure must be removed to allow sufficient room for adequate thickness of ceramic.

• Amalgam and composite are confined to intra coronal restorations. They will not restore strength to remaining tooth structure- Resin adhesion is strong in compression but, not in tension- Acid-etch union between enamel & resin provide protection to weakened cusps, but not reinforcement.

• Glass ionomer has low tensile strength & will not offer significant reinforcement to remaining tooth structure

3. Restoration and maintenance of occlusion: * Gold is the material of choice- Wear factor is almost identical to enamel

* Ceramic are useful for restoring anatomy and occlusion, however:

- Abrading opposing enamel- It is desirable to occlude porcelain to porcelain- Amalgam is next

* Composite and glass ionomer are not suitable, because their wear is too great

4. THE SIZE OF THE CAVITY

Large cavities require that the restorative material must be easy to manipulate and if the cavity is in a stress-bearing area the restorative must also have great strength properties.

Material selection according to cavity size

pits and fissure class I

- Small carious lesion: PRR- Moderate size cavity: composite resin or

amalgam restoration - Large cavity in molar with extensive occlusal

involvement GI lining + amalgam

Class II cavity

- New lesion only just involving the dentin ------> GI as principle restorative material laminated with composite resin

- Larger lesion with involvement of the marginal ridge ----> GI base + composite resin restoration, ceramic or composite inlay

• If the occlusal load is heavy ---------> amalgam

(Class II cont)

- Extensive lesion with undermined and weakened cusps --------> Gold, ceramic or composite onlay or amalgam+ additional retention (adhesive, pins, slots, grooves……..)

Class III:- initial lesion: composite resin,compomer or GI are

material of choice- Large lesion involving dentin ------> GI as dentin

substitute laminated with composite resin.

Class IV- only enamel involvement ------> composite

resin- Dentin involvement -----> (GI + composite)

sandwich

Cervical lesions:- Erosion abrasion lesions and class V caries lesion ------> GI is material of choice. If esthetic is unsatisfactory then GI is laminated with composite or (compomer in class V)

* Glass ionomer is also indicated as a restorative material in root caries.

Composite resin ?? Hybrid or micro-fill?? Microfill composite is used in class III, V, diastema closure, facial enamel, because of the high polishibility

* The use of microfill composite in cervical areas allows:

- optimal soft tissue response due to the high polishability

- their lower stiffness, compared to hybrid composite help in resisting displacement during tooth flexure

Hybrid composite:

is used in Class I, II, incisal fracture (class IV) Class III lingual surfaces because of their superior physical propertiesHowever, the polishability of currently available hybrids render them applicable for restoration of facial enamel, incisal fracture and diastema closure

5. AGE, PHISICAL CONDITION AND MENTALITY OF THE PATIENT

Very young, very old and sick and nervous patients cannot tolerate prolonged and difficult restoring operation; e.g. by direct gold. Amalgam is suitable for posterior teeth and composite and GIC for anterior teeth.

It may be even advisable to postpone this procedure and just have the carious lesion under control using temporary restorative material; i.e. IRM

6. FRIABILITY OF ENAMEL

• Cohesive gold and ceramic veneers are not a wise selection.

Composite resin or GI can be used

7. SENSIVITY OF DENTINPut the tooth on a rest treatment: (Temporary restorative material) then restore with a material which does not require excessive cutting in dentin during cavity preparation.

8. HYGIENIC CONDITION OF THE MOUTH

• Gold and ceramic are not a wise selection for patients with habitual unclean mouths.

• Composite restorations will fail under such conditions.

• Amalgam may undergo progressive and severe tarnish and corrosion.

• GI can be used as temporary or permanent resto.

9. Relatively high caries susceptibility

Use of permanent restorative materials is not recommended.

• Rampant caries treated temporarily until the period of high caries susceptibility ends.

• Later, proper cavities can be made and restored with the suitable permanent restorative material.

10. esthetics

The comparative importance of ESTHETIC versus the PHISICAL properties of the restorative material is sometimes a problem that requires to be discussed with the patient when restoring anterior teeth or even posterior teeth (posterior composite vs. amalgam).

• Ceramic: is the material of choice because it simulates the original color and translucency of the tooth structure(ceramic inlay, onlay, CAD-CAM, copy milled ceramic restorations, or ceramic veneers) Limitation: Destructive to remaining tooth structure

Composite resin: is the second choice ( direct composite, direct/ indirect composite, indirect restorations and veneers)

However, the integrity of the restoration margins depend on the availability of sound, well-supported enamel.

Glass ionomer: (Conventional, resin modified) and compomers are aesthetic restorations but with limitations where occlusal involvement is minimum

Composite restorations ????direct or indirect ???

• Direct resin utilizes the prepared tooth as the “working die” eliminating the need for impressions and models. The composite resin is placed, polymerized, removed from the prepared tooth and then treated extra orally with heat and additional light. Then it is bonded back into the tooth using resin cement• The indirect method utilizes impression of the preparation to fabricate the restoration in the lab

Indications for the Direct and indirect composite resin• Whenever an existing 1, 2 or 3 surface amalgam or

gold inlay would be the treatment planned.• To reinforce or strengthen large restorations by means

of bonding• In max or mand. premolar where esthetics is necessary

or in distolingual surface of max. canine• Where large isthmus is present and the cusp has

adequate dentinal support

How to choose between the different extra coronal restorative modalities

• Porcelain veneer vs composite veneer• 3/4 crown• full ceramic vs ceramic crown

Porcelain veneers vs composite veneers

Composite veneers:• Used to modify color or shape of one or two teeth• When patient refuse tooth preparation• One appointment procedure• Used for adolescent patients• Long term temporary restoration while completing

other treatment such as perio or ortho treatment

Limitations of composite veneers

• their use in lengthening teeth in function results in premature failure

• deterioration require periodic repair and replacement

Ceramic veneers

• Modify color, shape, length and alignment of teeth • Extensive modification of several teeth at a time• Close spaces (diastema closure)• Restore fractured and endodontically treated teeth

Advantages of ceramic veneers:• Perfect esthetics • Restore complete anatomy• Accurate fit Disadvantages or limitations• Lack of long term data on longevity• Possibility of post operative sensitivity • Marginal discoloration• Fracture• Wear of opposing teeth• High skill and multistage production• Relatively high cost

3/4 crown gold can be cast in thin section, therefore, 3/4 crown can be used to reinforce posterior teeth when the facial surfaces of the teeth are intact

Disadvantages• Multistage production• High skill required at each stage• Relatively high cost• Esthetics is doubtful

Full crown

is required where either the remaining tooth structure is badly broken down and no other method will restore the tooth or when it is necessary to correct esthetics or occlusion. If esthetics is not critical then cast gold is the material of choice to conserve tooth structure

12. Question of the fee

This must never justify using material of temporary nature or with inferior qualities. The economic status of the patient may modify the selection of the restorative material favoring the extensive use of amalgam.

11.THE PRESENCE OF OTHER METALLIC RESTORATION IN THE

MOUTH

Limits the selection to one type metal since the presence of dissimilar metals is productive of tarnish, corrosion and galvanism

Summary• Selection of the suitable restorative material may determine the success o failure of the final restoration.

• The ideal restorative material is yet to be found.

• Intelligent selection of restorative material depends upon thorough evaluation of the currently available restorative materials in the light of all the conditioning factors presented by each individual case.

Summary (cont.)

• Some of the conditioning factors may modify the selection of restorative materials but should never justify using material of inferior qualities unless decided by the patient after being discussed with him.

• In the absence of the ideal restorative material combination of two or more materials may be used to obtained the required qualities.