DLA 1201, exam 4

1. Matrix Systems
Light Curing

2. Matrix Systems
 Matrix bands
helps contain the restorative material within the preparation
during placement and to develop natural contours and contact
areas.

3. Matrix Systems
 Wedges
placed interproximally and hold the matrix band against the
tooth to seal the gingival margin, so that the restorative
material does not extend out of the cavity preparation and
cause an overhang.
Wedges are made of wood or plastic and are color-coded for
their size.

4. Matrix Systems
 Sectional matrix systems
Sectional matrix systems are used for class II
composite resins.
https://youtu.be/2R6tLhIQyOY

5. Matrix Systems
 Circumferential matrix systems
Circumferential matrix can be used with class II composite
resins, but it is very difficult to use.
If it is selected, a heavy wedge must be used to ensure a good
contact.
This is the problem with using a Tofflemire for a composite
restoration…
 https://youtu.be/upzeWfgvpQ8

6. Matrix Systems
 Cervical matrices
Cervical matrices are plastic matrices available for cervical
composites or glass ionomer restorations.
https://youtu.be/mDA-V3OmEQQ

7. Light-Curing
Light-cured composite resins must
receive the correct amount of radiant
energy at the right exposure time
and the right wavelength in order for
them to polymerize correctly.

8. Factors affecting the cure
Short curing times
Inadequate light output
Wrong wavelength of light
Incorrectly positioned light guide
The light guide should be held about 1 mm away initially and
then almost in contact with the composite after a second or
two.
The tip of the light guide should be positioned at 90 degrees
to the composite surface so the light shines directly on to the
composite.
Curing time should be increased when the light guide
angulation is compromised

9. Light Curing
Eye protection
The blue light emitted from a curing unit
can be damaging to the retina of the eye.
Eye protection should be worn by the
dental personnel and the patient when a
curing light is in use.
https://youtu.be/pik5xufB8mM

10. Composite Repair
Indirect Placement
Compomers and
Giomers
CHAPTER 6

11. Composite Repair
 Small fractures in a composite can be repaired rather than
replacing the entire composite restoration.
 A repair of a new composite is optimum, because the two
materials will have a chemical union
Unreacted methacrylate to join with the new addition
 In an older composite, there will be fewer unreacted
methacrylate groups present, and the bond will be weak.
The repair will rely more heavily on mechanical retention than
bonding.
The bond of new composites to the old composite in this case will be
less than 50% of the initially placed composite.
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12. Composite repair
The most successful repairs occur when there is
enamel rather than dentin on the tooth side of the
repair.
The area of composite that needs to be repaired, and
the adjacent tooth structure will both need to be
prepared.
Then, you would start as though you are preparing to
place a composite for the first time.

13. Finishing
 Finishing is the process used to correct irregularities in
contour, remove excess material, and smooth the margins
and external surfaces.
 Polishing takes the process a step further by removing
scratches by the step-wise application of sequentially finer
abrasives to produce a glossy, very smooth surface.
 The smoother the surface, the more it resists plaque retention
and makes cleaning with floss and brush much simpler.

14. Finishing
 Before starting this process, the restoration should be dried
and inspected for:
Integrity of the margin
Surface voids
Over- or undercountoured surfaces
Snug proximal contacts
 If a rubber dam is being used, inspection should take place
before its removal

15. Finishing
 Excess composite can be removed with multifluted carbide finishing
burs, fine and ultrafine diamonds, and abrasive disks.
 Small excesses at the gingival margin or interproximal can be removed
with special composite knives, a #12 surgical scalpel blade, flame-
shaped carbide or diamond burs, or abrasive strips.
 Carbide and diamond finishing burs and disks should be used at low
speeds with gentle, controlled (finger rest), intermittent strokes moving
from tooth to restoration so as not to ditch the margins or flatten the
contours.

16. Finishing
 With Intracoronal restorations the surrounding tooth structure is the guide to
developing the contours and shaping the occlusal anatomy.
 When using finishing strips to finish the gingival margin on the proximal
surface, be sure the strip is not so wide as to engage the contact area.
 It could produce a weak or open contact.
 When using abrasive disks on the convex surfaces as with cervical restorations,
smaller disks should be used and their angulation to the tooth should be
changed to follow the tooth contours.
 The restoration may be flat rather than convex like the tooth

17. Finishing
 Egg-shaped or football-shaped carbide and diamond finishing burs can be
used to finish and contour the occlusal surfaces of posterior teeth and lingual
surfaces of anterior teeth.
 Finishing is considered complete when:
 All “flash”, or excess composite extending over the cavosurface margins, have been
removed
 The cavosurface margins are flush and smooth feeling to the explorer
 The axial contours have been refined
 The occlusal anatomy shaped
 The occlusion adjusted
 Only when all surfaces have been properly finished, can the polishing be
started.

18. Polishing
 Polishing can be achieved by the use of:
 successive finer abrasive disks and interproximal finishing strips;
 rubber polishing points, cups, and disks impregnated with abrasives;
 polishing pastes
 A highly polished surface will not be achieved if steps are skipped in the progressing from courser
to finer polishers.
 Polishers should be moved from tooth to composite usuing light, intermittent strokes to prevent
the generation of heat.
 Polishing cups or points are used on the occlusal and other accessible areas.
 Some operators use polishing brushes to produce a high shine on occlusal surfaces
 A find disk can be used on facial, lingual and accessible proximal areas.
 Very find abrasive strips can also be used on proximal surfaces.
 Some operators will give a final polish with a soft brush and polishing paste to gain a high luster

19. Clinical Tip
The finishing process will be much easier if
care is taken during composite placement
to carefully develop contours and not
grossly overfill the cavity preparation!

20. Surface Sealers
 Surface sealers are unfilled resins that are added to the surface of the composite
after finishing and polishing.
 The surface sealer is thought to reseal margins that might have opened by
polymerization shrinkage and to fill in any surface porosities created by small
voids or air pockets in the composite.
 Finishing itself may introduce micro cracks on the surface and the low-viscosity,
unfilled resin can help fill and repair them
 To place a surface sealer:
 The composite is rinsed and died completely
 It and the surrounding enamel are etched for 15 seconds
 A thin layer of unfilled resin is applied and thinned further with a gentle stream of air
 Light cured for 20 seconds

21. Indirect-Placement Composite Resins
 Laboratory-processed composites
An indirect-placement composite resin
restoration can be made on a replica (die)
or from a digital impression of the
preparation and designed and fabricated
using CAD/CAM technology.
These are fabricated outside of the mouth
either in a laboratory or by using the
indirect chairside technique.
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22. Indirect Composites
Materials for indirect composites
Conventional composite
Fiber-reinforced composite
Contains fiber mesh composed of carbon Kevlar (the
material used in bullet proof vests), glass fibers, or
polyethylene for improved strength
Particle-reinforced composite
Heavily filled (70% to 80% by weight) with particles of
Nanosized ceramic filler

23. Indirect Chairside Technique
 An impression is made of the prepared tooth with alginate.
 Immediately, a fast-setting die stone or polyvinyl siloxane die material
is injected into the impression.
 The resulting die is used to make the restoration with light-cured
composite material at chairside
 The composite restoration is seated into the preparation and adjusted.
 It is removed from he mouth and polished on the die
 Then, it is cemented with resin cement in the same manner as
laboratory-processed composite inlays.

24. Glass Ionomer Cements Review
 Packaging
 Hand-mixed powder and liquid
 Encapsulated powder and liquid
 Two-paste systems
 Release fluoride
 Glass ionomer cements (GICs) are self-cured or light-cured, fluoride-releasing
materials that bond to tooth structures directly without bonding agents.
 Glass ionomers can be used as luting cements, restorative materials, and liners
and bases.
 Glass ionomers are sensitive to moisture uptake or loss during the first 24 hours
of placement.
 They are highly soluble during this time and should be covered with a protective
varnish.
 Glass ionomers are not very wear resistant, and they cannot be polished to a
smooth surface as composites can.
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25. Hybrid (Resin-Modified) Ionomers Review
 These resins have some properties of composites and some
properties of glass ionomers.
 They are stronger than regular glass ionomers, are easier to
polish, and are more wear resistant.
 Improved physical properties
To improve on the physical properties of glass ionomer, resins
(mostly in the form of 2-hydroxyethyl methacrylate [HEMA]) have
been added to the material.
 Dual cure materials
 Stronger
 Easier to polish
 More wear resistant
 Fluoride release
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26. Nano-ionomers
Nanoparticle technology has been applied to the
hybrid glass ionomer cements to improve their
physical properties.
Improved esthetics
Increased wear resistance
Improved polishability
Fluoride release
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27. Compomers
Compomers are essentially composite resins
that have been modified with polyacid.
The good qualities of the composite have
been married with the fluoride release of the
glass ionomer.
Light-activation chemicals included
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28. Giomers
Giomers are relatively new hybrid restorative
materials.
Giomers release fluoride but at a slower and
lower release than glass ionomers.
They can be recharged with fluoride toothpaste
or mouth rinse to act as a fluoride reservoir.
Packaged as single paste syringes or flowables
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