DLA 1201, exam 4

1. Clinical Handling of
Composites

2. Clinical Handling of Composites
Composite materials are used in all classes of
restorations, from class I through class VI.
In the anterior portion of the mouth, the material
selected is usually based on the ability of the
material to match the color of the teeth and
achieve a high polish.
Microfills, microhybrids, and nanohybrids are well
suited for this purpose.
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3. Selection of Material
 When incisal edges or other stress-bearing areas are being resorted, one of the
micro- or nano-hybrids should be considered because they are stronger than
microfills.
 Why?
 In the stress-bearing areas of the posterior part of the mouth, again, one of the
hybrid composites is usually chosen for its strength and wear resistance.
 Flowable composite should not be used in areas subjected to stress or abrasion,
because they are relatively weak and wear more rapidly.
 Macrofills generally have not been used much since the hybrids were developed,
because they do not polish well and leave a rough surface.

4. Clinical Handling of Composites
In stress-bearing areas of the posterior part of the
mouth, one of the hybrid composites is usually
chosen for its strength and wear resistance.
Flowable composites should not be used in areas
subject to stress or abrasion, because they are weak
and wear more rapidly.

5. Clinical Handling of Composites
Composite materials are also used for:
provisional restorations
core buildups
fiber-reinforced posts
laboratory-fabricated onlays and bridges.

6. Posterior Composite Resin
Advantages and Disadvantages
Advantages Disadvantages
Durable (but not for as long as amalgam) More costly than amalgam
Placed in one appointment Wear is slightly greater than with amalgam
Good compressive strength Shrinks when cured
Tooth colored (more esthetic) May leak, especially on root surfaces
Preparation more conservative than amalgam (less
tooth structure removed)
Technique sensitive- patient may have sensitivity
to cold or biting if restoration was not properly
placed
Bonding helps support the surrounding tooth Not a good choice for a very large restoration

7. Shade Guides

8. Shade Guides
 Many manufacturers include a shade guide with color tabs that can be
used to help in shade selection.
 Sometimes these color tabs are not an exact match to the composites
they represent.
 You could apply and cure a small quantity of the composite onto the clean,
moist tooth before the tooth is isolated and dried (desiccated) under isolation.
 After teeth are isolated (with rubber dam or cotton rolls), they tend to
dry out (desiccate) and will appear lighter in color than when they are
wet.
 How often are our teeth completely dry in a normal day?

9. Shade Guides
Shades should be selected before the tooth is
prepared or dried.
Good lighting is necessary
Natural light is preferred, but overhead or ceiling lights
can be used…
Keep them at a distance to decrease the intensity.
Heavy makeup and bright colored clothing can alter
the appearance of the shade.

10. Shade Guides
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The color tab should be:
Moist
Held adjacent to the tooth being restored
Viewed under different lighting conditions
Natural light is best.

11. Shade Guides
 Typically include 16 shades
 Shades are arranged on the display beginning with the light shades
and progressing to the darker shades….. Sort of…
 Teeth are predominately white, with varying degrees of
 Gray
 Yellow, or
 orange tints
 The shade also varies depending on:
 the patient’s age
 Thickness and translucency of the teeth
 Distribution of enamel and dentin on the tooth

12. Incremental Placement
Used in moderately sized or large cavity preparations
Placed in small increments
When large preparations are present, composite should be
placed in small increments no larger than 2 mm thick.

13. Incremental Placement
 Benefits of incremental placement:
Minimizes polymerization shrinkage
Because the shrinkage of the first increment is made p for by the
application of the next increment and continues with each successive
increment.
It permits light from the curing unit to adequately penetrate
and thoroughly cure each increment

14. Incremental placement
 If the composite resin is placed in too thick, the light might not penetrate completely
 The composite might not cure all the way to the bottom
 Longer curing times are required for increments greater than 2mm thick.
 Even with a longer curing time, some light-curing unites may not have the output needed to cure the
bottom of the large increment (>4mm)
 More powerful curing lights may be able to cure greater thicknesses… need to measure the output to
determine.
 Interproximal areas may need additional time to cure completely because of the more difficult
access of the area to the direct path of light.
 Its good practice to cure the interproximal composite restoration again from both facial and lingual
surfaces after the metal matrix band is removed to ensure complete curing in the bottom of the box form
of the preparation.
 Darker shades require longer curing times…
 Light is more readily absorbed by the dark color and does not transmit through the material as readily as through
the lighter colored materials

15. Resin-to-Resin Bonding
 Etched enamel and dentin are infiltrated with resin bonding agents to form a resin-
rich layer.
 The resin-infiltrated dentin is called the hybrid zone or hybrid layer
 The initial increment of composite resin will chemically bond to the resin bonding
agent on the enamel and dentin.
 Each additional increment will bond to the previously placed increment as long as good
isolation is maintained and no contaminants are introduced.
 When resins polymerize, there is a thin layer of unpolymerized resin on the surface
because of contact with oxygen in the air inhibits the cure.
 This “air-inhibited” layer looks shiny and feels slippery.
 This layer facilitates chemical bonding with the next layer of composite
 It will set when the layer placed over it excludes the air and then is cured.

16. Resin-to-Resin Bonding
 The completed restoration comprises a series of layers of resin-based materials that are all
chemically bonded to each other and micromechanically (mechanically locking into microscopic
irregularities created by acid etching) bonded to the tooth structure.
 Starting from the dentin side of the restoration and progressing toward the composite, there are
resin tags in the tubules:
 the resin-rich hybrid layer
 the adhesive resin layer
 the composite restoration
 In most cases, the final thin, air-inhibited layer on the surface is remove during finishing and
polishing.
 It may have an pleasant taste and should be wiped off with gauze before the patient leaves if finishing and
polishing aren’t required
 Sealant material!!

17. Contaminants
 Newly etched dentin is kept moist for “wet” dentin bonding.
 However, before and after bonding, any form of extraneous moisture (water, saliva, fluid from gingival sulcus, or
blood) should be kept away from the tooth until the restoration is completed.
 Contamination requires the removal of the contaminant and re-etching for 10-15 seconds.
 Alcohol should not be used to wet the composite placement instrument to keep the composite from
sticking because it weakens the composite
 Some doctors will ask for this though, because they are unaware of the chemical make up of newer materials.
 The use of a little of the bonding agent or other unfilled resin on the instrument to prevent sticking can
dilute and thin the composite, making it weaker and more likely to wear.
 Doctors will also ask for this as well
 Special composite instruments are made with a coating of nonstick materials to help with the stickiness
problem. They should be reserved for composite placement only, because once they get scratched, they
lose their nonstick quality.
 IRM, which contains eugenol; and liners, bases or temporary cements containing eugenol should NOT BE
USED WITH COMPOSITES, because the eugenol inhibits the set of resins.

18. Layering (Stratification) of Composite
 Some dentists prefer to apply layers of composite in different shades
or degrees of opacity or translucency to obtain a good match to the
natural teeth.
 this is called layering or stratification
 Teeth are usually not one color throughout, but a variety of colors
and can be described as three general areas:
 Cervical
 Body area
 Incisal

19. Stratification
Cervical area
Closest to the dentin color because of the translucent enamel is thinnest in
the cervical part of the tooth
Dentin color is the bulk of the tooth, and ranges from yellow to orange to
red mixtures
Dentin colored composites are more opaque to block out stains from
amalgam or tooth discolorations.
 Body area
Middle of the tooth
Color is the result of light interacting with both enamel and dentin.
The enamel is thicker in this area than in the cervical area

20. Stratification
 Incisal part of the tooth is mostly enamel and will be more translucent.
 Often the light will create a bluish tint to the enamel
 Cusp tips of posterior teeth are not translucent like anterior teeth, but will
appear lighter in color than the cervical or body areas.
 Dentists can select dentin, body and enamel shades and apply them in
layers to simulate the natural tooth colors with their opacities and
translucencies.
 When faced with a challenging color match, dentists may choose to do
a trial run or “mock-up” on the unetched tooth.
 Because the tooth has not been etched, the mock-up material will come off
easily

21. Factors of Clinical Handling of Composites
Shelf life
The shelf life of composites varies with the type of resin
used and the manufacturer.
The average shelf life is 2 to 3 years if stored properly.
Always check the label on the container to ensure it is not
expired.

22. Factors of Clinical Handling of Composites
Dispensing and cross-contamination
Light-cured composites are supplied in
compules or syringes.
All of these containers are opaque so that
the material is not affected by light.
Some offices prefer single-use (unit-dose)
items (such as, composite compules) that
can be disposed of after the procedure to
minimize the risk of cross-contamination.

23. Factors of Clinical Handling of Composites
 Reusable syringes require careful handling to ensure that they are not
contaminated during the procedure.
 The delivery tip on syringes should be disposed of in a sharps container after
use, and the syringes should be recapped and sprayed or wiped with
disinfectant.
 Composite in screw-type syringes should be dispensed after the shade is
selected and covered in a light-protected container until use.

24. Factors of Clinical Handling of Composites
 If the composite is stored in the refrigerator, it should be removed an hour or
more before being used.
 This allows it to return to room temperature.
 Cold composite will be stiff, less likely to stick to the placement instruments, but more difficult
to adapt to the wall of the cavity preparation.
 Composite syringes or compules can be placed in warm water to increase the flow
of the material.
 Devices are commercially available for warming the composite.
 Manufacturers claim that it can make highly filled composites flow like flowable
composites…..