Luting agents and cementation

Luting agents and cementation
Copyright (c) By Dr. Khin Swe Aye
Department of Conservative Dentistry
University of Dental Medicine, Yangon

1. Luting Cements and Luting 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

7. Unfortunately, no such product existsUnfortunately, no such product exists

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

9. Erosion of
Zinc
phosphate
cement seen
in a patient
with acid
reflux

10. Zinc Phoycarboxylate
Cement
Biocompatible
Adhesive to tooth substance
Viscous and difficult to mix
Not adhere to gold

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

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

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
.

22. Resin Cement –All Bond

23. Resin Cement - Panavia

24. Resin Cement – C&B Metabond

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

47. Armamentarium for bonding
procedure

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

54. A.Ceramic surface
(etched and
silanated)
B. Unfilled resin
C. Resin luting
agent
D. Etched enamel
Schematic of resin bonding technique

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