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Luting agents and cementation
1. Luting Cements andLuting Cements and
CementationCementation
Khin Swe Aye
B.D.S., Dip.D.Sc., M.D.Sc., Dr.D.Sc.,
F.I.C.C.D.E
Dept. of Conservative Dentistry
UDM (Ygn.)
2. ContentsContents
I. Introduction
II. Choice of Luting Cements
III. Try In
IV. Surface Treatment for Crown
Cementation
V. Cementation by GIC
VI. Cementation of Ceramic
Veneers and Inlays
3. I. IntroductionI. Introduction
Provisional cementation
•Used with temporary zinc oxide eugenol
(ZOE) cement
Definitive cementation
•Careless cement selection can result in
margin discrepancies and improper
occlusion
4. • Choice of cement depends on whether a
conventional casting or an adhesively
bonded restoration (ceramic inlay or
resin-retained FPD) is to be cemented
• Traditional dental cements can be used
for cast crowns and FPDs
• Adhesive resins are necessary for some
restorations
5. II. Choice of Luting AgentsII. Choice of Luting Agents
An ideal luting agent
has a long working time,
adheres well to both tooth structure and
cast alloys,
provides a good seal,
is nontoxic to the pulp,
has adequate strength properties,
6. is compressible into thin layers
has a low viscosity and solubility
exhibits good working and setting
characteristics
any excess can be easily removed
8. Zinc Phosphate Cement
Many dentists still use Zinc Phosphate
cement as luting agent if the teeth are
prepared conservatively
Cavity varnish can be used to protect
against pulp irritation from phosphoric acid
and appears to have little effect on the
amount of retention of the cemented
restorations
11. • In clinical trials, polycarboxylate performs
as well or slightly better than zinc
phosphate
• Reported varying success rates
• Claims of inferior long-term retention
have been made
• These problems may be related to the
powder/liquid ratio
12. • Working time of polycarboxylate is much
shorter than that of zinc phosphate
(about 2.5 minutes compared to 5
minutes)
• Its application therefore should probably
be limited to restorations with good
retention and resistance form where
minimum pulp irritation is wanted
13. Glass Ionomer Cement
Become popular luting cement for cast
restorations
Good working properties
Adheres to enamel and dentin
Exhibits good biocompatibility
Releases fluoride
Higher mechanical properties than zinc
phosphate cement and polycarboxylate
14. • During setting, GIC appears susceptible
to moisture contamination and should be
protected with a foil or resin coat or by
leaving a band of cement undisturbed for
10 minutes
• Should not be allowed to desiccate
during this critical initial setting period
15.
16.
17. Resin modified GIC
low solubility
adhesion
low microleakage
(The popularity of these materials is
mainly due to the perceived benefit of
reduced post cementation sensitivity)
less susceptible to early moisture
18.
19. • 2-ethoxybenzoic acid (EBA) modifier replaces
a portion of the eugenol in conventional ZOE
cement
• Reinforced ZOE cement is extremely
biocompatible and provides an excellent seal
• However, its physical properties (strength,
solubility, and film thickness) are generally
inferior to those of other cements
Zinc Oxide-eugenol
with and without EBA
20. Adhesive Resin
Unfilled resins have been used for
cementation since the 1950s
Developed for resin-retained prostheses
Eextensively used for bonded ceramic
technique
Bonding is usually achieved with
organophosphonates;
HEMA (hydroxyethyl methacrylate), or 4-
META (4 methacrylethyl trimellitic anhydride)
21. • Because of their high polymerization
shrinkage and poor bio-compatibility
(especially if they are not fully polymerized),
these early products were unsuccessful,
although they had very low solubility
• tend to have greater film thickness
.
27. III. Try-in
Temporary, Provisional, or Permanent
Choose your words very carefully
This will affect your patient’s expectations
Temporary - tomorrow
Provisional - ?? a month
Long Term - years
Permanent - for life
28. Remove temporary crown
Isolate from saliva
Wash and gently dry the preparation
Try-in the crown
keep hold of it – do not drop it
If you must let go, use a temporary cement
Check the bite, appearance etc.,
Make sure your patient is happy with it
Recement temporary crown with temporary
cement
29. Before you proceed to porcelain,
try your metal framework in first,
Look at the crown before you see the pt.
Has technician followed your instructions?
Do check this the day before patient is
back
30. A fully seated crown, no open margins,
with good fit and no rocking
Marginal adaptation, no ledges or catch;
neither over-extended nor short
Retention is good, with no rotation or twist
off
Occlusion accurate, or with good
clearance present for porcelain coverage
31. Don’t rush, this is an irreversible step!
There is no UNDO button
Once a well fitting crown is cemented with a
good luting cement, it is extremely difficult
to remove it without any damage to - Fine
metal margins, which will crinkle
- Porcelain, which will chip or flake
32. This is a good idea if there is any doubts
Waiting for sensitivity to settle
Checking occlusal load/wear patterns
Testing appearance
Testing phonetics
Testing function
Trying a raised occlusal position
Patient must understand the need to for
regular follow up reviews and reassessment,
and what will go wrong if their treatment is not
completed
33. IV. Surface Treatment for
Crown Cementation
Surface treatment involves surface
modification of both tooth and restoration
To enhance the surface contact and
adhesion of the luting cement
34. The restoration and tooth must be thoroughly
cleaned and dried after the try-in procedure
The casting is best prepared by air-abrading
the fitting surface with 50-µm alumina
done carefully to avoid abrading the polished
surfaces or margins
(Air abrasion has increased the in vitro
retention of castings by 64%)
Alternatives; steam cleaning, ultrasonics, and
organic solvents
35. A. Clean and dry
preparations
B & C.
Steam cleaner is
convenient for
removing traces
of polishing
compound from
the restorations
D & E.
Air abrasion of
internal
restoration
surface
36. V. Cementation by GIC
Step 1. Surface treatment
Inspect the preparation surface
Remove provisional cement or staining
(with pumice and hydrogen peroxide)
Clean the casting (with air-abrasion,
steam, or ultrasonically, alcohol)
(Then, make try-in whether the
restoration fits well)
37. Step 2. Moisture isolation
With cotton roll
Place saliva evacuator
Rubber dam especially for intracoronal
cementation
38. Step 3. Mixing the GI cement
Mixing pad
Mix according to manufacturer’s
instruction
Mix the first increment 10 sec. and the
second increment another 10 sec.
39. Step 4. Apply a thin coat of
cement to the clean internal surface of
the restoration
40. Step 5. Seating the restoration
Dry the tooth
Seat the restoration and rock (dynamic
seating force)
Avoid excessive force especially with
metal-ceramic or all-ceramic restoration
(it may fracture)
41. Step 6. Check the margins
To verify that the restoration is fully in
place
Protect the setting cement from
moisture by covering it with an adhesive
foil
42. Step 7. Removal of excess
When the cement is fully set, remove
excess cement with explorer
Use dental floss to remove the excess
cement from interproximal spaces and
sulcus
Check the occlusion
43. Step 8. Give instruction
Cements take at least 24 hours to
develop their final strength
The patient should be cautioned to
chew carefully for a day or two
44. VI. Cementation of Ceramic
Veneers and Inlays
These restorations rely on resin
bonding for retention and strength
The cementation steps are critical to the
restoration’s success; careless handling
of the resin luting agent may be a key
factor in their prognosis
45. Available in a wide range of formulations
Categorized on the basis of;
1) polymerization method (chemical-cure,
light-cure, or dual-cure)
2) the presence of dentin bonding
mechanisms
Metal restorations require a chemically cured
system, whereas a light- or dual-cure is
appropriate with ceramics
Resin Luting Agents
46. Bonding is achieved by performing the
following steps:
Etching the fitting surface of the ceramic with
hydrofluoric acid
Applying a silane coupling agent to the
ceramic
Etching the enamel with phosphoric acid
Applying a resin bonding agent to etched enamel
and silane
Seating the restoration with a composite resin
luting agent
48. Step 1. Mouth preparation
Clean the tooth with pumice and water
Isolate moisture with rubber dam or
displacement cord
Remove ZOE cement if present by
cleansing with pumice and then etching
the tooth with 37% phosphoric acid
49. Step 2. Try-in
Try in restorations with glycerin or a try-
in paste
Verify fit, shade, and insertion
sequence
Check occlusion
50. Step 3. Tooth surface treatment
Acid-etch the enamel
(37% phosphoric acid x 20 seconds)
Rinse thoroughly and dry
51. Step 4. Restoration surface
treatment
Clean the restoration thoroughly in water
with ultrasonic agitation
Use acetone if luting resin was used to
verify the shade at try-in
Dry the restorations
Etch with hydrofluoric acidhydrofluoric acid and silanatesilanate the
restoration
52. Step 5. Application of bonding
resin
Apply thin layer of bonding resin to the
preparation
(Brush, rather than air-thin, because air-
thinning might inhibit polymerization)
Do not polymerize this layer, because it
might interfere with complete seating
53. Step 6. Application of resin
cement
Apply composite resin luting agent to the
restoration (careful to avoid trapping air)
Dual-cure is recommended for inlay and
onlays
Light cure is recommended for veneers
55. Step 7. Seating the restoration
Position the restoration gently, removing
excess luting agent with an instrument
(For veneers, place a Mylar matrix strip at
the mesial and distal surfaces of the
prepared tooth)
56. Step 8. Removal of excess
cement
Use dental tape to remove resin flash
from the interproximal margins of inlays
and onlays before curing these areas
57. Step 9. Light-curing the resin
Hold the restoration in place while light-
curing the resin
Do not press on the center of veneers,
they may flex and break
Do not under-cure the resin cement
Allow at least 40 seconds for each area
58. Step 10. Finishing and polishing
Remove resin flash with a scalpel or sharp
curette
Finish accessible margins and occlusion with
fine diamonds, using water spray
Use finishing strips for the interproximal
margins
Polish adjusted areas with rubber wheels or
points and then with diamond polishing paste