Resto Sem Report Common Errors

7/28/2019 Resto Sem Report Common Errors

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Failures of Amalgam

CAUSE EFFECT

Too shallow cavity

Thin AmalgamToo thick cavity liner

Too thick cement base

Inadequate cuspal reduction

Thin Amalgam (over the cusp)

Giving cavosurface bevel

Sharp axio-pulpal line angle

Stress Concentration

(isthmus)Sharp angles in occlusal

outline form of Class II

Fracture of the Restoration


3/40

Failures of Amalgam

CAUSE EFFECT

Sloping gingival step

No Resistance Form(isthmus)

Too narrow gingival step

Insufficient Hg

Weak AmalgamExcess Hg

Undertrituration

Moisture contamination

(Zn having alloys)

Delayed Expansion

(flow over margins)



4/40

Failures of Amalgam

CAUSE EFFECT

Insufficient condensation pressure

Increased Residual HgNot squeezing out excess Hg

Mix squeezed too dryLack of Cohesion

(amalgam weak)Condensation of partially crystallized amalgam

Overfilling Thin Amalgam Over Margins

Failure to warn patient not to chew on the

restoration for first few hours

Early Strength Not High EnoughFailure to support proximal part of the restoration

while removing matrix band



5/40

Failures of Amalgam

CAUSE EFFECT

Sharp angles in occlusal outline

of Class IIStress concentration

Excess removal of tooth structure

Enamel undermined and

tooth weakened

Fracture of the Tooth


6/40

Failures of Amalgam

CAUSE EFFECT

Absence of undercuts No retention form

Dovetail with only one cornu No resistance to dislodgement

Too thick liner that is lost

subsequentlyLack of adaptation to cavity walls

Using large condensers initiallyUndercuts and margins not filled

- No retention

Inadequate Retention


7/40

Failures of Amalgam

CAUSE EFFECT

Excess Sn (tin) in the alloy Too much shrinkage

Overtrituration Shrinkage on setting

Excessive pestle pressure Slow setting with shrinkage

Failure to condense towards margins Marginal gaps

Using large condensers initiallyDeficient margins and

undercuts

Carving from amalgam to tooth Marginal defects and gaps

Excess amalgam left beyond

cavosurface angles

Breaks away leaving deficient

margins

Marginal Leakage


8/40

Failures of Amalgam

Porous and Weak Amalgam

CAUSE EFFECT

Increased 2 Phase (low Cu alloys) Weak phase

Irregularly shaped particles in the alloy Porosities and voids;less coherence of phases

Too less Hg Same as above

(Incomplete amalgamation; non-plastic)

Too much Hg Increased residual Hg

(Increased 2Phase , decreased 1 Phase phases)

Undertrituration Porosities & voids

Trituration beyond limits Decreased coherence(due to cracking of crystals)

Delayed insertion after trituration

Porosities and voidsInsertion of too large increments

Decreased condensation pressure Porosities and voids

(increased residual Hg)


9/40

Failures of Amalgam

Porous and Weak Amalgam

CAUSE EFFECT

Moisture contamination Porous amalgam

Mix squeezed too dry Decreased coherence

Mix not squeezed (with high Hg:Alloy ratio) Porosities and voids

(increased residual Hg)

Condensation of partially crystallized amalgamPorous amalgam

Condensing with serrated pluggers with set

amalgam in the serrationsOld amalgam contaminates restoration and

weakens itOverheating while polishing 'Burns' amalgam and releases H

resulting in porosity

Burnishing set amalgam Breaks up superficial crystalline structure

releasing Hg causing porosity


10/40

Failures of Amalgam

Tarnish and Corrosion

CAUSE EFFECT

Alloy with excess 2 Phase Has least resistance to corrosion

Fissures carved too deep Food stagnation leading to tarnish and

corrosion

Failure to polish Rough surface causing crevicularcorrosion

Contact with dissimilar metallic

restoration Galvanic corrosion


11/40

Failures of Amalgam

Gingivitis and Periodontitis

CAUSE EFFECT

No wedge used Gross overhang;

Contact area deficiency

Surface left high in biteHigh point causing periodontitis

Failure to polish proximalsurface

Food stagnation resulting in gingivitis and

periodonitisLack of proximal contact


12/40

Failures of Amalgam

Lack of Functional Efficiency

CAUSE EFFECT

Fissures carved too deep

Reduced masticatory efficiencyUnderfilling

Failure to carve Decreased masticatory efficiency(tooth anatomy not simulated)


13/40

Failures of Amalgam

Pain after Placing restoration

CAUSE EFFECT

Failure to use liner and base Thermal conduction

Overfilling High point causing periodontitis resulting in pain

Moisture contamination Delayed expansion with pressure on pulp

Increased Hg: alloy ratio Mercuroscopic expansion with pressure on pulp

Failure to squeeze out excess Hg

Mercuroscopic expansion(increased residual Hg)Inadequate condensation pressure

Cavity preparation without water coolant

Pulpitis resulting in painMicroscopic pulp exposure


14/40

Sometimes, excess Hg within the restoration may seep

through the dentinal tubules, discolor dentin and result

in blackish or grayish staining of teeth.

Since enamel is semi- translucent, this discoloration is

not inconspicuous.

Failures of Amalgam

Tooth Discoloration


15/40

most commonly carried out using volumetric dispensers or

preproportioned capsules

the advantages of the latter are:

o that the dentist does not have to worry

about getting the right ratio of alloy to

mercury

(as this is prefixed by the manufacturer)

o that there is less danger of mercury

spillage during the handling stages of

amalgam placement

unfortunately, the capsules are more expensive than

buying the alloy powder in bulk

Proportioning


16/40

TRITURATION

adequate trituration is essential to ensure a plastic mix and

thorough amalgamation

trituration time needed is dependent upon both the type of

alloy being used and the dispensing and mixing system

trituration times affect the dimensional changes that occur

when amalgam sets


17/40

most important demands on the condensation technique are:

that as much excess mercury is removed as is possible

that the final restoration will be non- porous

that optimum marginal adaptation is achieved so as to

prevent postoperative sensitivity

important components in condensation are:

the use of maximum force

the use of suitably sized condensers in relation to

cavity size

the use of multiple and rapid thrusts

the placement of small increments.

CONDENSATION


18/40

burnishing more recent studies indicate that the overall effect of

burnishing is to:

increase surface hardness

reduce porosity and decrease corrosion

improve the marginal adaptation of the amalgam


19/40

Over filling, under filling, and over carving

if a cavity is overfilled and is not then carved back

sufficiently to provide a smooth transition from the tooth

surface to the restoration surface, a ledge will result

this ledge will eventually fracture, and give the appearance

of marginal breakdown of the restoration

under filling or over carving can result in an acute amalgam

margin angle that will give rise to marginal breakdown


20/40

Fracture Lines

Marginal Ditching

Proximal Overhangs

Poor Anatomic Contours

Failures of

Amalgam Restorations

Signs of Failures

Marginal Ridge Incompatibility

Improper Proximal Contacts

Recurrent Caries

Poor Occlusal Contact

Amalgam Blues


21/40

Amalgam Tattoo

accidental implantation of silver containing compounds

into oral mucosal tissue

occurs:

removal of old amalgam

broken pieces entering socket (tooth extraction)

particles entering surgical wounds

amalgam dust in oral fluids (abrasion areas)


22/40

Amalgam Tattoo

common sites:

gingiva

buccal mucosa

alveolar mucosa

seen as grayish black pigmentation


23/40

GlC sets within 6- 8 minutes from the start of mixing

setting can be slowed when the cement is mixed on

a cold slab

this technique has an adverse effect on strength

conventional glass ionomer restorations are difficult to

manipulate as they are sensitive:

to moisture imbibitions during the early setting

reaction

to desiccation as the materials begin to harden

Failures of g. i. c.


24/40

secondary or marginal caries

most common failure of glass ionomer

restorations

7 years

median age of restoration failure for

glass ionomer

Failures of g. i. c.


25/40

Failures of composite resins

Undercured Composites

brighter light means deeper and faster curing

of the composite

many older lights are not bright enough to cure

the full depth of a posterior composite filling

can be solved by filling the tooth in thin

increments and curing each incrementthoroughly before placing the next increment

newer arc lights and laser curing units are so bright

that they can cure to a greater depth quite quickly


26/40


Undercured Composites

the tooth will remain sensitive for a very long time

only solution for this problem is toremove the filling and replace it with aproperly cured composite or an amalgam


27/40


Shrinkage Stress

plastics tend to shrink when they transform from theliquid to the solid phase

(similar to the way water tends to expand when frozen)

microscopic shrinkage always happens

can cause the vertical walls of the

preparation to be drawn together whichcan produce prolonged sensitivity to cold


28/40


Shrinkage Stress

slicing

a simple technique used to release the stress

the dentist cuts a vertical groove from the top

of the filling to the floor of the preparationfrom mesial (front) to distal (back) throughthe filling

this allows the cusps on either side to rebound

relieving the stress

the groove is then refilled with composite and

the filling is then as good as new


29/40


Shrinkage Stress

the use of clear plastic matrix bands

another way to avoid shrinkage away

from the walls of the prep

allows the curing light to be directed

through the plastic from the side of

the tootho this would cause the composite to be

drawn toward the cavity prep wallsand eliminate the shrinkage away

from them


30/40


Shrinkage away from the Floor of the

Cavity Preparation

composite tends to shrink toward the light

since the light source is usually directed

from the top of the tooth

often causes the filling material to pull

away from the floor of the cavitypreparation allowing a tiny void to formunderneath the filling between thebottom of the filling and the tooth surface


31/40



Cavity Preparation

the void eventually fills with fluid and cancause hydrostatic pressure in the dentinaltubules which leads to sensitivity to pressureon the filling

this is the most common reason for pain when

biting on a newly done composite filling

only solution for this problem is to redo

the filling


32/40



Cavity Preparation

the dentist can often avoid this problem:

o by placing the composite in increments

that cover only part of the floor

o by the use of a self curing glass ionomerbase used under the composite


33/40


White line or halo around enamel

margin (microfracture of marginal

enamel)

Causes:

1. Traumatic contouring or finishing

techniques2.Inadequate etching and bonding of the

area


34/40


White line or halo around enamel

margin (microfracture of marginal

enamel)

Solution:

1. Re-etch, prime, and bond the area2.Conservatively finishing techniques (lightintermittent pressure)


35/40


Voids

Causes:

1. Mixing of self cured composites2.Spaces left between increments during

insertion3. Tacky composite pulling away from thepreparation during insertion


36/40

Voids

Potential Solutions:

1. More careful technique

2.Repair of marginal voids by preparingthe area and re restoring



37/40


Weak or missing proximal contact

Causes:

1. Inadequately contoured matrix band2. Inadequate wedging, both preoperatively and

during the composite insertion

3. Tacky composite pulling away from matrix contactarea during insertion


38/40


Weak or missing proximal contact

Solution:

1. Properly contour the matrix band2.Have matrix in contact with adjacent

tooth3.Use firm insertion wedging technique


39/40

Incorrect Shade


Cause:

1. Inappropriate operator lightning while selectingthe shade

2. Selecting the shade after the tooth is dried

3. Shade tab not matching the actual compositeshade

4. Wrong shade selected


40/40


Incorrect Shade

Possible solutions:

1. Use natural light if possible2. Select the shade before isolating the tooth3. Preoperative place some of the selected shade on

the tooth and cure (then remove)4. Do not shine operating light directly on the area

during shade selection

Documents

Resto Sem Report Common Errors