5. ..
Cementation is defined as, “The
process of attaching parts by
means of a cement” –GPT.
•Cementation
6. ..
The clinical success of fixed prosthodontic restorations can be
complex and involve multifaceted procedures. Preparation
design, oral hygiene/microflora, mechanical forces, and
restorative materials are only a few of the factors which
contribute to overall success. One key factor to success is
choosing the proper luting cement. This clinical update will
review several luting cements, their physical properties, clinical
implications, and recommendations for usage.
7. ..
An ideal luting cement would have: easy
manipulation, low film thickness, long working time
with rapid set, low solubility, high compressive and
tensile strengths, high proportional limit, adhesion to
tooth/restoration, anticariogenicity, biocompatibility,
and translucency or radiopacity. Physical properties
should be taken into consideration along with handling
characteristics, technique sensitivity, and results from
long term clinical trials .
8. ..
Most cements are formed by an acid-base
reaction. Liquids may be phosphoric acid, polyacrylic
acid, or eugenol. Powders are either zinc oxide or
aluminosilicate glass. Resin cements, however, are not
acid-base formed but utilize BIS-GMA or urethane
dimethacrylate resins. Cements can be classified into
five groups: phosphate bonded, polycarboxylate bonded,
phenolate bonded, resin cements, and glass
ionomer/hybrid cements.
9. Long working time.
Adhere well to both tooth structure and
cast alloy.
Provide a good seal.
Non-irritating, non-toxic to both pulp and
surrounding supporting structure.
Have adequate strength properties.
Being compressible to thin layers i.e. have
low viscosity; low solubility.
Exhibit good working and setting
characteristic.
Easily to be removed after setting.
Fluoride release.
13. Composition:
ZnO powder and phosphoric acid
Advantages:
Long clinical track record (used clinically for
over 50 years(.
Specimens of cement retrieved from old
castings (>40 yrs) show high chemical stability.
Adequate strength (80-110 MPa c.s,5-7 MPa
t.s(.
Reasonable working time (3-6min w.t, 5-14 s.t(.
Excess material can be easily removed.
14. Disadvantages:
Water-sensitive during setting; microleakage; high
solubility especially in acid environment (0.05 to
3.3% in d.w, 20 to 30 times higher in acids(.
Pulp irritation Low initial pH (1-2 after mixing,
below 4 to 1 h,6-7 after 24 h); (use of varnishes?(.
Lack of antimicrobial action
Brittleness,
lack of adhesion.
15. It is good for general/routine use
and recommended for long
span fixed partial dentures
due to its rigidity.
Good ForGood For??
16. High compressive strength (152
MPa) and a moderate tensile
strength (9.3MPa( .
Excessive film thickness 88 µm at
the occlusal surface under an actual
casting.
An acidic pH that may be harmful to
the pulp.
17. . Durelon (3M ESPE AG) and Tylok Plus
(Dentsply/Caulk) are examples of
polycarboxylate cements.
18. Composition:
The powder is zinc oxide with 1% to
5% tin or magnesium oxide, 10% to
40% aluminum oxide or other
reinforcing filler, the acid is 40%
(high MW) polyacrylic acid or
acrylic acid coplymer with other
organic acids.
Good for cementing crowns and 3-
unit bridges.
19. Exhibits specific (low) adhesion to tooth
structure because it chelates with the calcium.
Adhesion to some alloys.
Higher tensile strength (8-12 MPa) compared to
zinc phosphate cement, but significantly lower
compressive strength (55-85 MPa(.
Anticariogenic in nature but this property is less
than that of GIC.
Biocompatible to the pulp , rapid rise of the
cement PH toward neutrality.
Lack of post operative sensitivity. (excellent for
sensitive teeth(
Film thickness comparable to those of zinc
phosphate cements
Solubility in distilled water 0.1% to 0.6%.
20. Disadvantages
◦It is thixotropic in nature. Hence, it may be too
thick and will not flow adequately.
◦Short (2.5min)working time as compared to that
of Zn/Po cement(5min) makes it difficult to lute
long span bridges
◦Residual cement is more difficult to remove.
◦Not as strong as Zn/Po.
◦Shows plastic deformation, so unsuited to high
load areas
21. Manipulation
◦The cement should be mixed on the surface that
does not absorb liquid; hence, a glass slab is
preferred to treated paper pads.
◦The liquid should not be dispensed prior to
mixing because it tends lose water
◦The powder is rapidly incorporated in bulk as
two increments into the liquid in large quantities
within 30 seconds using a Glass slab and
stainless steel spatula.
◦Cooling the slab increases the setting time.
◦Should not be disturbed in rubbery stage as will
pull from margins
22. This cement is recommended for
single units and short
span fixed partial denture
It is also recommended for
hypersensitive teeth and when
preparations come close to the pulp..
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23.
24. Composition: alumino-fluorosilicate
glass and weak polyacrylic acids
Adhesive, and reports of reduced
microleakage
Early exposure to water significantly
reduces ultimate strength
Low cement film thickness (25 to 35µm(
Does not appear to be more irritant to
pulp, as earlier reports suggested
25. Advantages
◦Cement has adhesion to enamel and dentin (low bond
strength to teeth(.
◦Exhibits good biocompatibility (no pulpal protection is
required(.
◦It releases fluoride (anticariogenic effect(.
◦Easy to mix , good resistance to acid dissloution.
◦Set cement is translucent (advantage when used with
porcelain labial margin(.
◦Mechanical properties are comparable with zinc
phosphate cement (medium-high compressive
strength 90 to 140 MPa, T.S 6 to 8 MPa(.
26. Disadvantages
◦long term sensitivity can result if tooth is over
dried.
◦High susceptibility to moisture contamination.
during setting, (more recent formulations may
be less susceptible than the earlier products(.
◦Slow setting, possible pulp irritation.
◦variable adhesive characteristic.
◦Residual cement is more difficult to remove.
27. These cements are excellent
for general prosthodontic
use. Fluoride release may be
beneficial for some patients. Avoid
using glass ionomer with
hypersensitive teeth.
Good ForGood For??
28. Resin modified polyalkenoate cement
(Mixture of resin and glass ionomer
powder(
Combines the strength and insolubility of
resin with the fluoride release of glass
ionomer.
Manufacturers recommend their
use for all-metal or ceramo-metal
crowns and bridges, , but not for
posts (risk of expansion induced
root fracture(
Not recommended for all-ceramic
restorations, because delayed cement
expansion can result in ceramic fracture
29. Working time can be lengthened by
using refrigerated liquid, mixing on cold
slab or decreasing powder-liquid ratio.
Higher temperature shorten working
time.
Use microetching to prepare internal
metal surfaces for increased bonding.
Remove excess cement before final set.
Use desensitizing liquid to reduce
possible sensitivity without dramatically
affecting bond to tooth.
30. Zinc Oxide Eugenol (ZOE) was developed by Dr. J.
Foster Flagg in 1875 (3). Zinc oxide powder reacts
with water, forming zinc hydroxide. Zinc hydroxide
then reacts with the eugenol to make zinc
eugenolate. Zinc eugenolate is a very soluble
cement because it can hyrolyze back into zinc
hydroxide and eugenol (i.e. a reversible reaction
31. ZOE cement is relatively weak in strength when compared to other
cements. Orthoxybenzoic acid can be added to the eugenol and
alumina or poly (methyl methacrylate) can be added to the powder to
increase the cement’s strength. This cement is known
to have an obtunding effect on the pulp.
Because of its weak strength and high solubility, zinc oxide eugenol
cement may be questionable as a permanent luting
agent.
Fynal (Dentsply/Caulk) is a reinforced zinc oxide eugenol cement
32. This cement may be used on very
sensitive teeth that have excellent
retention/resistance form.
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33. Examples of resin cements include PANAVIA
(Kuraray Co., Ltd.) Calibra (Dentsply/Caulk),
and Variolink (IvoclarVivadent, Inc.).
34. Composition: Bis-GMA resins and
other methacrylates.
Available in a wide range for
formulation. These can be categorized
on the basis of polymerization into:
(Chemical-, photo- and dual-cure(
Adhesion to enamel by
micromechanical retention to dentine
by more complex penetration of
hydrophilic monomers through
collagen layer overlying partially
demineralized apatite of etched
dentine
35.
36. Conditioning: removal of smear layer,
and demineralize top 2-5 microns
Primer: wetting agent such as HEMA
(Hydroxy Ethyl Metacrylate ) applied;
bifunctionality enables hydrophilic bond
to dentine and hydrophobic bond to
adhesive
Adhesive cement: e.g. 4-
META(Methacryloxy Ethyl Ttimillitic
Anhydride) penetrates into tubules
Polymerization shrinkage remains a
problem
37. The manipulative techniques may
be very different with different
brands of resin cements.
Shade of veneers can be modified
by the shade of the luting agent
Colour-match try-in pastes are
available to facilitate selecting the
best cement shade.
39. Disadvantages:
◦The need for meticulous and critical
technique,
◦More difficult sealing and higher film
thickness than traditional cements,
◦Possible leakage and pulp sensitivity,
◦Difficulty in removal excess cement
40. Resin cements are suitable for luting
porcelain, cast ceramic, and composite
restorations and recommended for
teeth
that have inadequate
retention/resistance after preparation
Good ForGood For??
41. Zinc oxide –eugenol: powder zinc oxide,
the liquid is purified eugenol.
Low compressive and tensile strength(7-
40 MPa, 1000-6000P psi(.
Film thickness of 40 µm
High solubility about 1.5%, little
anticariogenic action
Abtudent effect on the pulp, good sealing
ability and resistance to marginal
penetration.
Reinforced zinc oxide-eugenol cements:
by adding EBA, alumium oxide and PMM.
42.
43. Primary purpose of luting cement: to seal
tooth-restoration interfacial space
Choice of luting agent
Type of restoration: conventional casting
or adhesive restoration
44.
45.
46. After cleaning the preparation,
cavity varnish should be applied if a
non-adhesive cement like zinc
phosphate is to be used.
Oxalate treatment of the tooth
surface can be done to reduce
dentin sensitivity.
47. The casting should be cleaned by sandblasting with 50 µm
alumina or by steam, followed by ultrasonic or organic cleaning.
Next the operatory site is isolated with cotton rolls.
The cement should be mixed to a luting consistency.
A thin coat of cement should be applied on the internal surface of
the casting.
The tooth surface is dried and the prosthesis is inserted with a
firm, rocking dynamic seating force. A static load will lead to
incomplete seating. Excessive force may lead to fracture.
Next the margins of the retainers are examined to verify the fit of
the prosthesis.
Excess cement should be removed with an explorer. Floss can be
used to remove the excess cement in the inter-proximal surface.
Occlusion should be checked with Mylar shim stock or articulating
paper.
The patient should be advised to avoid loading for the first 24
hours.
54. Viscosity of the cement.
Morphology of the restoration.
Vibration.
Seating force.
Venting.
55.
56. Clean tooth and isolate. Do not use
compressed air. If tooth is dry, moisten
with a wet cotton roll.
Excessive air drying of the preparation may
cause post-cementation sensitivity.
Seat casting, then clean up excess cement
after it hardens.
If patient has sensitivity, delay final
cementation for 2-3 weeks.
57. Fluff powder before dispensing. Hold liquid bottle
vertically, and release each drop slowly to ensure
equal size drops.
For any powder/liquid cement, incorporate the
powder thoroughly. Insure mix is homogeneous.
Load the crown evenly with cement.
Place crown cement-side done on your palm for the
dentist to pick up and seat on the tooth.
As the cement loses its gloss and start to set, it will
have a stringy, non-sticky consistency. Start
removing excess cement before it hardens.
After removal of excess, use a piece of knotted floss
and run it through the interproximal areas to remove
remnant cement.
Instruct patients to wait 1 hour after cementation.
58. Clean tooth.
Rinse and dry – do not desiccate the tooth.
Powder is sensitive to moisture – keep container
tightly sealed.
Fluff powder before dispensing.
Make sure tip of liquid vial is clean before
dispensing.
Dispense liquid form vial held vertically to ensure
uniform drops.
Mix all powder into liquid for 20-30 seconds on a
small area of mixing pad.
59. The patient is asked to exercise all oral functions and
awareness should be created regarding the initial
discomfort.
Sudden impact forces should be avoided in the
restored area, e.g. biting on a nut or metallic object.
Maintenance:
Oral hygiene procedures with special attention to use of
floss, inter-dental brushes in the concerned area.
De-sensitizing tooth paste or mouth wash can be used if
there is sensitivity.
The patient is advised to report immediately if there
is pain.
Regular recall visits for review.
60. A resin-based desensitizer can be placed
on the prepared tooth prior to cementation
to decrease the potential for post
cementation sensitivity when using zinc
phosphate or glass ionomer cements.
These desensitizers should not adversely
effect crown retention
61. Post-cementation appointment (within a
week to 10 days(
Periodic recall – patients with cast
restoration are recalled at least every six
months
Patients with extensive fixed prosthesis
combined with advanced periodontal
disease needs more frequent recall
appointments.
62. SummarySummary
Indications and contraindications for luting agent types
Restoration Indicated Contraindicated
Cast crown, PFM crown, fixed partial denture 1,2,3,4,5,6 -
Pressed ceramic crown, ceramic inlay, ceramic
veneer, resin bonded FPD
1 2,3,4,5,6
Patient with history of post-treatment sensitivity 3,6 1
Crown or FPD with poor retention 1 2,3,4,5,6
Cast post and core 1,2,4,5 3,6
Key:
1=Resin cement 2=Glass ionomer 3=Reinforced ZOE
4=Resin reinforced glass ionomer 5=Zinc phosphate 6=Zinc polycarboxylate
