Restoration failure

Failure of

Dental Restoration

Republic Of YemenUniversity Of AdenFaculty Of Dentistry

Under supervison : Dr. Muneera Ghaithan

Objective :

o Definitiono General Causes of Failureo Failure of Dental Amalgamo Failure of Dental Compositeo Conclusion

Definition :

It is Inability or inadequacy of a dental restoration or prosthesis to perform as expected.

What is Success ?

The criteria of success of a dental restoration include : Restoration remains integral and in place. Absence of recurrent Caries. Marginal accuracy and adaptation. Perfect aesthetics. Maintain perfect anatomy and relations

with neighboring and opposing teeth and periodontal Structures.

Patient comfort and satisfaction.

General Causes of Failure :

Causes of failure can be listed as either inherent factors or induced factors :

1- Inherent Factors Tough conditions in the oral cavity: Different Types of Stress. Temperature fluctuations. PH Cycling. Humidity. Micro-organisms. Shelters and stagnation areas

Causes of failure can be listed as either inherent factors or induced factors :

1- Inherent Factors Tough conditions in the oral cavity: Different Types of Stress. Temperature fluctuations. PH Cycling. Humidity. Micro-organisms. Shelters and stagnation areas

General Causes of Failure :

2- Induced Factors Misjudgment in selecting the correct

restorative material. Incorrect design of cavity preparation Imperfect manipulation of the

restoration.

Failure of

Dental Amalgam

Usually amalgams lasts for about 10 years

“linical failure is the point at which the restoration is no longer serviceable or at which time restoration posses other severe risk if it is not replaced”

Failures in amalgam restoration are not usually because of poor material

Everything done from time of cavity preparation until restoration is polished has a definite affect on the restoration

Failures of dental amalgam :

Amalgam failures can be :

At visual level

Secondary caries

Marginal fracture

Bulk fracture

Tooth fracture

Dimensional change

At the microstrutur

al level

Corrosion and tarnish

Stresses associated

with masticatory

forces

Pain following amalgam

restoration

Pulp and/or periodontal involvement

Causes of amalgam failures :

Failures due to faulty case selection

Failures due to faulty cavity preparation

Failure due to poor matrix adaptation

Failures due to faulty amalgam manipulation


Failures due to faulty case selection1 Extensive occlusal caries Wide open contacts Dissimilar metals

Due to faulty cavity preparation2


Greatest single factor for failure Healey & philips (1949) * 56% - cavity * 42% - manipulation Faulty cavity preparation recurrance

of caries and fracture

During cavity preparation the failure occuar at various step :


A-Inadequate occlusal extension : inadequate extension to pits and fissure increase chance of caries recurrence particularly in high caries risk individuals

B-Inadequate extension of proximal box :If inadequately extended into embrasures, they are not amenable to brushing and cleaning by mastication secondary caries.

C-Overextension of cavity preparation walls :

Ideal faciolingual width of cavity is ¼ of intercuspal distance

If the width is more than ½ ,capping should be considered

If width more than 2/3, capping is a must Chance of fracture because restoration act as

wedge and tend to split opposing cusps apart During capping there should be an amalgam

thickness of 2mm on functional and 1.5mm over non-functional cusps


D-Amalgam cavity should have minimum depth : of 1.5mm to provide it bulk and hence resistance to fracture

E-If pulpal floor is not flat :Restoration produces wedging effect fracture of tooth

F-Cavosurface angle butt joint If acute tooth fractureIf obtuse collapse of marginal amalgam



G-inadequate proximal retention form / narrow isthmus fracture at isthmus portion

H-extensive mesio-distal extension undermining of marginal ridge enamel fracture

I-incomplete removal of carious tooth materialfailure of amalgam restoration

DUE TO POOR MATRIX ADAPTATION3


Proper contacts and contour in restoration obtained by matrix

Instability of matrix distorted restoration,gross marginal excess and uncondensed soft amalgam with voids

Cervical excess can result in periodontal irritation destruction of periodontium


DUE TO FAULTY AMALGAM MANIPULATION4

1- Mercury alloy ratio : if residual mercury is in excess of 55% loss

of strength Under trituration soft powdery non-

coherent mix Over trituration break already formed

matrix


2- Condensation : to ensure amalgam reach all parts of the

preparation and obtain homogenous restoration devoid of voids

Larger cavities multiple mix should be used to get homogenous restoration

Small increments should be used to ensure proper condensation

Mechanical condenser should be used with caution as it would cause fracture of enamel margins

3- Contamination :


Moisture contamination can occur during - trituration - mulling

- condensation Weaken the restoration especially if zinc

containing It result in marginal flaws, tarnish, pitting,

corrosion, and blistering. Expansion may also lead to pain

4- Finishing and polishing :


Amalgam should be finished gently Excess spur like overhangs or thin flakes of

amalgam on margins can fracture easily which can leave crevices in vulnerable areas

Polishing should be done judiciously, temperature above 65 0c leads to release of mercury leading to deffective restoration

Repairing of amalgam restoration :

Appropriate depth and retention form must be generated

If necessary, another matrix must be placed A new mix of amalgam can be condensed

directly into the defect and will adhere to the amalgam already present

If the amalgam has been bonded, carefully condition and apply adhesive to the exposed tooth structure in the preparation

Failure of

Dental composite

Causes of composite failures :

1. Incomplete removal of carious lesion

2. incomplete etching or incomplete removal of residual acid from tooth surface

3. Excess or deficient application of bounding agent .

4. Lack of moisture control .

5. Contamination of composite with finger / saliva .

6. following bulk placement technique during polymerization of composite .

7. Improper polymerization method .

8. Incomplete finishing and polishing of composite .

9. Inadequate occlusion of restored tooth .

Following failures are commonly seen in composite restoration with time :

Causes of composite failures :

Discoloratin

Secondary caries

Gross fracture of restoration

Postoperate

sensitivity

Fracture of

margins

Loss of contact

Accumulation of plaque

Marginal defect in composite restorations :

Surface fracture of excess material

Voids in restoration because of air entrapment during placement

Composite wear resulting in progressive exposure of axially directed wall

Gaps formation

Marginal defect in composite restorations can be occur in the following forms :

32

1

4

Guideline to minimize composite failure :

1. The tooth preparation should be kept as small as possible since composite in bulk lead to failure .

2. Avoid sharp internal line angles ,which increase stress concentration.

3. Deeper preparation should be given base of CA(OH) or GI cement.

4. Strict isolation is to be followed.

5. Avoid inadequate curing ,since it lead hydrolytic breakdown of composite.

6. Use small increments, holding each increment with Teflon coated instruments.

7. Fill proximal box separately and create proper contact areas .

8. Composite ,especially at beveled areas ,should be finished and polished properly.

Repairing composite restorations :

Restoration is indicated for replacement when any of following occurs :

Secondary caries which cannot be removed during repair procedure.

Need for aesthetics.

Presence of pulpal pathology


• Easily accessible areas may be roughened with a diamond stone

• the area is etched; primer may be applied if dentin is exposed

• adhesive is applied• finally the composite is

inserted, contoured, and polished

If a patient presents with a composite restoration that has a localized defect

• a tooth preparation must be created that exposes the defective area and a matrix may be necessary

• placement of the etchant, primer, adhesive

• composite is then performed

If the defect is not easily accessible


• more composite can be added directly to the void area. These materials will bond because the void area has an oxygen-inhibited surface layer that permits composite additions.

• If, however, any contouring has occurred, the oxygen-inhibited layer may been removed or altered and the area must be re-etched and adhesive placed before adding more composite.

If a void is detected


Conclusion :

1.The criteria of success of a dental restoration include many factor

2.Causes of failure can be listed as either 3.inherent factors or induced factors4.Failures in amalgam restoration are not

usually because of poor material5.During cavity preparation the failure occuar

at various step6.The tooth preparation should be kept as

small as possible since composite in bulk lead to failure

7.Composite ,especially at beveled areas ,should be finished and polished properly.

Prepared by :

Group B 1

Health & Medicine

Restoration failure