o Definitiono General Causes of Failureo Failure of Dental Amalgamo Failure of Dental Compositeo Conclusion
The criteria of success of a dental restorationinclude : 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.
Causes of failure can be listed as eitherinherent 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
2- Induced Factors Misjudgment in selecting the correct restorative material. Incorrect design of cavity preparation Imperfect manipulation of the restoration.
Usually amalgams lasts for about 10 years“linical failure is the point at which therestoration is no longer serviceable or atwhich time restoration posses othersevere risk if it is not replaced”Failures in amalgam restoration are notusually because of poor materialEverything done from time of cavitypreparation until restoration is polishedhas a definite affect on the restoration
At visual At the Pain following Pulp and/or microstrutural amalgam periodontal level level restoration involvement Secondary Corrosion and caries tarnish Marginal Stresses associated fracture with masticatory forces Bulk fractureTooth fracture Dimensional change
Failures due to faulty case selection Failures due to faulty cavity preparation Failure due to poor matrix adaptationFailures due to faulty amalgam manipulation
1 Failures due to faulty case selection Extensive occlusal caries Wide open contacts Dissimilar metals
2 Due to faulty cavity preparation 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 increasechance of caries recurrence particularly in high cariesrisk individualsB-Inadequate extension of proximal box :If inadequately extended into embrasures, they are notamenable 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 tofractureE-If pulpal floor is not flat :Restoration produces wedging effect fracture of toothF-Cavosurface angle butt jointIf acute tooth fractureIf obtuse collapse of marginal amalgam
G-inadequate proximal retention form / narrow isthmusfracture at isthmus portionH-extensive mesio-distal extensionundermining of marginal ridge enamel fractureI-incomplete removal of carious tooth materialfailure of amalgam restoration
3 DUE TO POOR MATRIX ADAPTATION 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
4 DUE TO FAULTY AMALGAM MANIPULATION1- 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
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
1. Incomplete removal of carious lesion2. incomplete etching or incomplete removal of residual acid from tooth surface3. 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 compositerestoration with time : Discoloratin Accumulatio Secondary n of plaque caries Loss of Gross fracture of contact restoration Fracture of Postoperate margins sensitivity
Marginal defect in composite restorations can be occurin the following forms : 1 Surface fracture of excess material 2 Voids in restoration because of air entrapment during placement 3 Composite wear resulting in progressive exposure of axially directed wall 4 Gaps formation
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.
Restoration is indicated for replacement whenany of following occurs : Secondary caries which cannot be removed during repair procedure. Need for aesthetics. Presence of pulpal pathology
If a patient presents with a compositerestoration that has a localized defect• 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 the defect is not easily accessible• 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 a void is detected• 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
1. The criteria of success of a dental restoration include many factor2. Causes of failure can be listed as either3. 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 failure7. Composite ,especially at beveled areas ,should be finished and polished properly.
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.