2. INTRODUCTION
• Dental cements have been in use in dentistry for
a very long time.
• They serve several purposes such as retaining
restorations and prosthesis in the mouth.
• Also restorative, endodontic, orthodontic,
periodontic as well as surgical procedures.
• Last 2 decades have seen a variety of changes in
the dental cement composition and also
introduction of newer advanced biocompatible
materials.
4. DEFINITION
• Cements:1. to unite or make firm by or as if by
cement; to lute.
2. a material on hardening will fill a space or bind
adjacent objects.
[GPT, 9]
• A cement is a substance that hardens to act as a base ,
liner , filling material or adhesive to bind devices or
prosthesis to the tooth structure or to each other. -
philips’ science of dental materials (12th ed)
13. Cements as luting agent
• The word ‘luting’ is derived from a latin word Lutum-
which means mud.
• Dental luting agents provide a link between the
restoration and prepared tooth, bonding them
together through some form of surface attachment,
which may be mechanical, micro-mechanical, chemical
or combination.
• Luting agents may be definitive or provisional
depending on their physical properties and planned
longevity of the restoration
14.
15. • A prepared surface on microscopic level is
rough ,exhibits valleys and peaks.
• When 2 surfaces are placed togather some
have point contact some may not .
• The space created allows seepage of oral
fluids and infections.
• So to fill the gap luting cements are used.
• Current approach for cementing prosthesis
suggests use of adhesive technology.
16. LUTING MECHANISM(By Schillinburg)
• Non-Adhesive:
Cement fills the restoration-tooth gap and holds by
engaging in small surface irregularities
Micromechanical Bonding:
Surface irregularities are enhanced by air abrasion or
acid etching • Improves the frictional retention
Molecular Bonding:
Chemical bond formation between cement and the
tooth structure
17. PROCEDURE FOR LUTING PROSTHESIS
• PROCEDURE CONSISTS OF
• Placing cement on inner surface of prosthesis
• Seating the prosthesis
• Removing excess cement at appropriate time
18. PLACEMENT
• To be effective a luting cement should be sufficiently fluid
to flow in a thickness 25 µm without fragmentation.
• Cement should fill half of interior of the crown.
• Occlusal aspect should be free of voids.
Complete filling is not advisable because
The risk of bubble entrapment increases
Time of seating increases
Time for removal of excess increases
Increased pressure may be required.
19. SEATING
• Moderate finger pressure
• Patient is asked to bite on soft piece of wood
or cotton
• Variables that facilitate seating is
Lower viscosity
Decreasing height of crown preparation
Regular tapping while applying pressure.
Increasing taper
Evaluation of occlusion
Evaluation of marginal
seal at min. 3 points
hyperocclusion
•Thick layer
Marginal ditching
20.
21. REMOVAL OF EXCESS
• Zinc phospahate and ZOE should set
completely before the excess is removed.
• Zn polycarboxylate, GIC, resin cements vary
among products.
• Seperating medium if applied
• Dual cure resins and type 1 GIC are left for 1.5
to 3 min as viscosity increases .if it is removed
before it turns into solid then the whole
cement may come out.
22. Dislodgement of prosthesis
• Fixed prostheses can debond because of
biologic or physical reasons or a combination
of the two.
• There are two basic modes of failure
associated with cements.
• Cohesive fracture of the cement and
separation along the interfac
23. General requirements for luting agents
• Biocompatibility
• Retention
• High tensile strength, fracture toughness and
fatigue strength
• Good marginal seal
• Low film thickness
• Radiopacity
• Aesthetics
• Ease of use
24. CHARACTERISTIC PROPERTIES OF
DENTAL CEMENTS
• FILM THICKNESS & CONSISTENCY
Height of space between two surfaces separated by cement
Eg:distance between tooth surface and cemented crown
Determines the adaptation of the restoration to the tooth.
Consistency is the way in which a substance, typically a liquid, holds
together.
Consistency of the cement should be thick and plastic enough for ease of
handling and placement into the cavity
Heavier the consistency : Greater the film thickness and so
Less complete the seating of restoration.
25. • Maximum allowable film thickness
• For luting application : 20-25 µm
• For restorative application -temporary/final cementation
: 40 µm
Ultimate film thickness depends up on the
• Particle size of the powder
• Concentration of the powder in liquid
• Viscosity of liquid
• Consistency of cement
• Amount of force and manner which the force is applied
26. VISCOSITY
• Resistance of a liquid to flow
• It is a measure of consistency
• Factors affecting viscosity
• Increase in temperature and time - increase
the viscosity of certain cements
27. SETTING TIME
• The elapsed time from the start of mixing to the
point at which the mixture reaches a desired
hardness or consistency.
• Net setting time: Time elapsed between the
end of the mixing and the time of setting
• Working time: Elapsed time from the start of
mixing to the maximum time at which the
viscosity of the mix is low enough to flow readily
under pressure to form thin film.
28. STRENGTH & SOLUBILITY
• ANSI /ADA specification recomends that the standard
luting consistency of dental cement must exhibit a
minimum 24 hr compressive strength of 70 Mpa.
• Solubility in oral fluids & water - Water based cements are
more soluble than resin or oil-based cements •
• Decrease in P:L ratio : higher solubility and disintegration
rate •
• ADA - 0.2Wt% •
• Maximum permissible rates of dissolution •
• GIC : 0.1 wt% . Zinc Phosphate : 0.2 wt% • Zinc
Polycarboxylate : 0.3 wt%
29. Silicates
• Introduced in 1903 as anterior filling materials.
• Silicates are attacked by oral fluids and in time
degrade, They may not be considered
permanent restoration.
• The uses of silicate cements diminished with
the advent of composite resins and
development of GIC.
• Powder: Silica, Alumina , Fluoride compounds
, Calcium salts
• Liquid : Phosphoric acid , Water , Buffer salts
30. • Setting Reaction
Powder mixed with liquid.
Powder attacked by acid liquid releasing Ca, Al, Fl ions
Metal ions precipitate as phosphate cement matrix inclusive of Fl salts
• Advantages
It exhibit good esthetic qualities .
Anticariogenic property.
Analogues to topical applied fluoride solution.
• Disadvantages
It lacks stability in oral fluids with loss of esthetic qualities
Rubber dam is essential for successful restoration
Irritant to pulp
31. Zinc Phosphate cement
• COMPOSITION
• POWDER
• Zinc Oxide - Principle Ingredient
• Magnesium Oxide - reduces the temp. of calcification process 2.10% aids in
sintering.
• Oxides of Bismuth
• Calcium - Impact a smoothness to freshly mixed Barium Cement mass. In large
quantities lengthen the S.T
• Silicon Dioxide - In active filler
• LIQUID
• Phosphoric acid - 45-64% Reacts with ZnO
• Water - 30 – 55% Increases Rate of reaction
• Aluminum phosphate- 2.3% Essential to the cement forming reaction
• Zinc - 0.9% Moderates reaction between powder and Liquid allows adequate
working time
32. • CLASSIFICATION (Anusavice 9th edition )
• Type I -Fine grained for luting -Film thickness
should be less than 25 um
• Type II - - Medium grained for luting and filling -
Film thickness should be more than 40um
Applications
Permanent luting of well-fitting, prefabricated and cast
posts, metal inlays, onlays, crowns, FPDs, and aluminous
all-ceramic crowns to tooth structure, amalgam,
composite, or glass ionomer core build ups.
33.
34. • Powder mixed with liquid, phosphoric acid attacks
surface of particles and releases Zn ions into liquid.
• Alluminium forms a complex with phosphoric acid
reacts with zinc and yeilds zinc aluminophosphate gel.
• Set matrix is cored structure of unreacted ZnO
embedded in cohesive matrixof aluminophosphate gel
35.
36. Variations in Zinc Phosphate Cement
Fluoridated cement
• Small % of stannous fluoride
• Lower strength & higher solubility than zinc phosphate
• Fluoride release continues over long period
• reduces enamel solubility ,increases hardness
• This activity should reduce the incidence of enamel decalcification under
orthodontic bands. o Used in orthodontic band cementation.
Copper/Silver cement
• Consists of proportion of red or black cuprous oxide or copper salts or
silver salts to zinc oxide powder.
• Liquid same as conventional. Used in past due to germicidal action
• Were discontinued due to staining of teeth.
37. Silicophosphate cement
Combination of zinc phosphate & silicate cement. Contains small
amounts of mercury compounds.
Composition: Silicate glass & minor amount of zinc oxide,13-25%
fluoride Liquid contains 50% phosphoric acid,45% water,4-9% zinc, 2%
Al.
Advantages : Better & toughness than zinc phosphate. Fluoride
release & degree of translucency. Lower solubility & better bonding.
Disadvantages : Less satisfactory mixing & rheological properties
Leading to higher film thickness & greater potential for pulp
irritation.
Used for cementation orthodontic bands & restoring non vital teeth
38. ZINC OXIDE EUGENOL (ADA SP. NO. 30)
• Introduced by Chrisholm in 1873
• Commonly used for luting and intermediate
restorations
• Obtundant property on exposed dentin
• APPLICATION
• Longterm and short-term luting agents
Temporary and intermediate restorations
• Root canal sealers
• Surgical packs
39. TYPES (ADA Specification No. 30)
Type I : Temporary
restorations
Type II : Permanent
cementation of
restorations
Type III : Temporary
restoration, thermal
insulating bases
Type IV : Cavity
Liner
Two
paste
Powder
liquid
40. COMPOSITION
• Powder
• Zinc oxide (principal ingredient).
• Zinc stearate (accelerator, plasticizer).
• Zinc acetate (accelerator, improve strength).
• White rosin (to reduce brittleness of set cement).
• Liquid
• Eugenol (react with zinc oxide).
• Olive oil (plasticizer).
• Setting time 4-10 minutes (zinc oxide eugenol cement sets quickly in the
mouth due to moisture and heat).
• Powder /liquid ratio (4/1 to 6/1 by weight).
41.
42. ADVANTAGES DISADVANTAGES
Obtundant effect on pulpal tissues Low strength and low abrasion resistance
Good sealing ability Microleakage
Resistance to marginal penetration Disintegration in oral fluids
Good thermal insulation Less anticariogenic
Solubility is highest among all cements
43. MODIFICATIONS OF ZOE
• PROPERTIES • Solubility is lower than ZnO
eugenol cement due to the presence of resin
• BIOLOGIC EFFECTS • Inflammatory reaction in
the connective tissue is present • Softening and
discoloration of the resin material
REINFORCED
ZINC OXIDE
EUGENOL
CEMENT
•SETTING REACTION • Appears to form chelate
salt between EBA, eugenol and zinc oxide.
MANIPULATION • Similar to ZnO eugenol •
Cement mixes readily to very fluid consistency
even at a high P:L ratio
• Setting time 7 - 13 mins
EBA MODIFIED
ZINC OXIDE
EUGENOL
44. POLYCARBOXYLATE CEMENT (ADA SP.
NO. 96)
• Dennis Smith : 1968
• First cement system with adhesive bond to tooth
structure
• Also known as polyacrylate cement
• APPLICATION
• Luting alloy restorations • Thermal insulating
bases • Cementing orthodontic bands •
Cementing SS crown in pediatric dentistry
46. • The cement sets by an acid–base reaction when zinc
oxide powder is mixed with viscous solution of high
molecular weight polyacrylic acid.
• The powder contains 4% stannous fluoride but it does
not impart any anticariogenic property because
fluoride released is only 10–15% of that released by
the glass ionomer cement. However, it acts as a
strengthening agent.
• The adhesive bond is primarily to enamel although a
weaker bond to dentin also forms as a result of
chelation reaction between the carboxyl groups of
the cement and calcium in the tooth structure; hence,
the more mineralised the tooth structure, the
stronger the bond.
47. • Freshly mixed cement has honey-like consistency with the property of being
pseudoplastic and shows shear thinning behaviour. Therefore, though the mixed
cement appears too thick, it flows adequately under pressure to a film thickness
of 25–35 lm.
• During setting, the cement passes through a rubbery stage and should remain
undisturbed to prevent it from being pulled away from the margins.
• Polycarboxylate cement exhibits significantly greater plastic deformation than
zinc phosphate , it is not well suited for use in regions of high masticatory stress
or in cementation of long-span prosthesis .
• It is recommended for vital or sensitive teeth with preparations close to the pulp
and for cementing single units or short span bridges in areas of low stress.
48. SETTING REACTION
• Chemical reaction of acid-base type
• Zinc oxide + PAA -> zinc- polycarboxylate
• Set material compose of zinc polycarboxylate matrix with
unreacted zinc oxide particles dispersed in providing
cement its opacity
• Speed of reaction affected by
temperature
p/l ratio
powder particle size
mixing rate
49.
50. ADVANTAGES DISADVANTAGES
Low irritation Lower compressive strength
Chemical bond to tooth structure and
alloys
Greater viscoelasticity
Easy manipulation Need for clean surfaces for adhesion
Adequate strength Short working time
Low solubility
Anticariogenic
Adequate film thickness
51. GLASS INOMER CEMENT
• Definition of glass ionomer cement
• A cement that consists of a basic glass & an acidic
polymer which sets by an acid-base reaction between
these components. (Mclean,Nicholson & Wilson 1994)
• The essential elements of a true glass ionomer : • Acid-
base setting reaction
. Ion-exchange adhesion with underlying tooth structure
• Continuing ion activity, with mobility of fluoride,
calcium and phosphate ions
52. CLASSIFICATION
• According to A.D Wilson
• Type 1: Luting agents
• Type 2: Restorative cements a)aesthetic filling
material b)bis-reinforced filling material
• Type 3: Lining, base and fissure sealing
materials
53. According to application
• Type 1- luting
• Type 2- restoration
• Type 3- liners and base
• Type 4- pit and fissures sealants
• Type 5- luting for orthodontic purpose
• Type 6- core build up material
• Type 7- fluoride releasing GIC
• Type 8- for ART
• Type 9- for pediatric purpose
55. SETTING REACTION
• When the powder & liquid are mixed, Surface of
glass particles are attacked by acid.
• Then Ca, Al, sodium, & fluoride ions are leached
into aqueous medium.
• The poly acrylic acid chains are cross linke by Ca
that are repalced by Al in 24 hr.
• Sodium and fluorine ions dont participate in cross
linking.
• The cross linked phase matures overtime by same
water used during mixing(maturation)
56. So the set cement is the agglomeration of unreacted powder
particles surrounded by silica gel in an amorphous matrix of
hydrated calcium and alluminium polysalts
57. STAGES IN SETTING REACTION (Based on the work of
Crisp and Wilson 1972-1974)
Decomposition: of glass and release of cement forming
metal ions (A13+ and Ca2+)
Migration: of these metal ions into the aqueous phase
of the cement.
Gelation: of the polyacid by metal ions leading to set.
Post set hardening: when metal ions become
increasingly bound to the polyacid chain. (continues for
24 hrs)
Further Slow Maturation: takes place even after 24
hrs. Translucency develops further as does resistance
of desiccation and acid attack.
58.
59.
60. • Advantages:
• Chemical bonding
• Sustained fluoride release and ability to absorb fluoride from the oral
environment (fluoride recharge) makes it the cement of choice in patients
with high caries rate.
• Coefficient of thermal expansion similar to tooth
• Translucent, can be used with porcelain crowns
• Adequate resistance to acid dissolution
• Low film thickness and maintains constant viscosity for a short time after
mixing, so better seating of restorations
• Disadvantages:
• Initial slow setting and sensitivity to early moisture contamination and
desiccation
• Modulus of elasticity lower than zinc phosphate, so potential of elastic
deformation in areas of high masticatory stress
• Initial low setting pH was assumed to be associated
• with post cementation sensitivity .
61.
62. MODIFICATIONS
1. Water settable glass ionomer cement :-
Liquid is delivered in a freeze dried form
,which is incorporated into the powder. Liquid
used is clean water.
63. Resin modified glass ionomer cement
• RMGIC can be defined as a hybrid cement that sets via an acid base reaction and
partly via a photo- chemical polymerization reaction.
• Composition • Powder: Ion leachable glass and initiators for light / chemical /
both types of curing
• Liquid : water + Polyacrylic acid modified with MA and HEMA monomers.
• The HEMA content is around 15-25% and water content is low to accommodate
the polymerizable ingredients.
• It is a powder : liquid system with P:L = 3:1
• Setting reaction
• 2 distinct setting reactions occur
• Acid base neutralization + Free radicle MA cure.
• This can occur purely via light cure or by a combination of LC and chemical cure.
• Thus a cement can be termed –
• dual cure if cross linking is via acid base + LC
• tri cure if its via acid base + Light cure + chemical cure
64. Esthetics: there is a definite improvement in translucency as the
monomer brings the refractive index of the liquid close to that of
the glass particle.
Fluoride release: is same as that of the conventional
Strength: The diametrical tensile strength is much higher but
compressive strength and hardness is lesser.
Adhesion: to tooth is reduced. This is expected because of
reduction in carboxylic acid in the liquid and interruption of
chemical bonding due to the resin matrix.
Micro leakage: A higher degree of Microleakage is seen due to
polymerization shrinkage • also due to reduced water and
carboxylic acid content and reduces its wetting capacity
• Recommended for luting metal or porcelain-fused-to metal crowns
and FPD’s to tooth, amalgam, resin composite,or glass ionomer
core buildups
65. 3 .Metal modified glass ionomer cement :-
Glass ionomer have been modified by addition of
filler particles ,to improve strength ,fracture
toughness & resistance to wear.
Silver alloy admix / miracle mix:- This is made by
mixing of spherical silver amalgam alloy powder
with glass ionomer powder.
Cerment:- Bonding of silver particles to glass
ionomer particles by fusion through high
temperature sintering.
66. Compomer
Compomer is a combination of the word ‘comp’
for composite “omer” for ionomer is a composite
resin that uses an ionomer glass which is the
major component of glass ionomer as the filler.
Small quantity of dehydrated polyalkenoic acid
incorporated with filler particles,
Setting reaction is light activated.
Adhesive system used with compomer is based
on acid etch found with all composite resin.
67. • Compomers for luting purposes are available as a two component
system, either powder/liquid or as two pastes
Powder: strontium aluminofluorosilicate, metallic oxides, chemical-
activated and/or light-activated initiators.
• Liquid: polymerizable methacrylate/carboxylic acid monomers,
multifunctional acrylate monomers, water.
• Because of the presence of water, these materials are self-adhesive
and an acid–base reaction starts at the time of mixing
• Tensile strength, flexural strength and wear resistance of compomer
is superior to the conventional glass-ionomer cement but less
effective than resin composites .
• They are recommended primarily for cementing prosthesis with a
metallic substrate
68. • Restorative compomers are available as one-component,light-
curable material which consists of silicate glass particles, sodium
fluoride and poly-acid modified monomer but no water.
• Initially, setting occurs due to photopolymerization which is
followed by an acid–base reaction when the set material absorbs
water.
• This eventually results in fluoride release, although limited .
• Because of the absence of water in restorative compomers, they
are not self-adhesive like conventional GIC and resin-modified
GIC, thereby requiring separate dentin bonding agents
69. ADVANTAGES
Superior working characteristics to RMGIC
Ease of use
Easily adapts to the tooth
Good esthetics
INDICATIONS
P& F sealant • Restoration of primary teeth, class III
and V lesions along with cervical abrasions and
erosions and intermediate restorations • Bases for
composites, liners • Small core build ups • Filling of pot
holes & undercuts in old crown preparations • Root
surface sealing
70. RESIN BASE CEMENTS
COMPOSITE AND ADHESIVE RESINS
Polymeric cements that set via polymerization
reactions.
Resin cements are essentially flowable composites
of low viscosity.
Applications
Cementation of:
Crowns. Resin bonded bridges. Inlays and onlays.
Orthodontic brackets. Veneers. Posts and Cores.
71. • Resin cements used today are composed of resin
matrix of bis-GMA or urethane dimethacrylate and
filler of fine inorganic particles (20–80%) to ensure thin
film thickness.
• They are available as powder/liquid, encapsulated, or
paste/paste systems and are classified into three types
based on the method of polymerization as
• chemical-cured,
• light-cured and
• dual-cured.
72. Advantages:
• Superior compressive and tensile strengths
(20–50 MPa) with low solubility
• Micromechanical bonding to prepared
enamel, dentin, alloys and ceramic surfaces
• Available in wide range of shades and
translucencies
73. Disadvantages:
• Meticulous and critical manipulation technique
• High film thickness
• Marginal leakage due to polymerization shrinkage
• Severe pulpal reactions when applied to cut vital dentin
• Offers no fluoride release or uptake
• Low modulus of elasticity, so cannot support long span
prosthesis.
• Difficulty in removing hardened excess resin cement
from inaccessible areas, precluding its use when
subgingival margins are placed.
• Use of eugenol-based provisional luting agents
inhibited the complete polymerization of the resin
cement
74. Adhesive Resin Cements
• In order to improve the adhesive bond of conventional
bis GMA resin cements, adhesive monomers have been
added that will enable chemical bonding to both the
tooth structure and the suitably prepared metal
surfaces.
• The adhesive monomer incorporated into the resin
monomer and cements include:
• i. HEMA
• ii. 4 – META(Methacryloxyethyl trimetillic anhydride)
• iii. An organophosphate e.g. MDP (10-
methacryloxydecamethylene phosphoric acid).
76. • Resin bonding is facilitated by the affinity of these
monomers for the metal oxides present on the
base metal alloys without the need for acid
etching .
• However, these resins have low affinity for
precious metal alloys due to the lack of surface
oxide coating and low chemical reactivity
requiring need for some surface modification to
achieve chemical bonding (tin-plating, silicoating
or use of new metal primers)
77. • Polymerization
• By conventional chemical cure system with an organic
peroxide e.g. BPO as an initiator.
• Light activation; addition of an alpha diketone and an
aliphatic amine
• applied where curing is practical e.g. through thin
porcelain veneers (like Porcelite), resin based
prostheses that are less than 1.5mm in thickness, and
plastic and ceramic orthodontic appliances.
• Dual cure
78. Properties of Resin Cements
• Insoluble in oral fluids.
• Monomer is a pulp irritant, thus line with
Ca(OH)2 or GIC if dentine thickness ≈ 0.5mm or
less.
• Compressive strength: 180-265MPa.
• Tensile strength: 30-63MPa.
• Viscosity: Low to high.
• Film thickness: 13-20 μm.
• Shear bond strength to enamel: 15- 35MPa.
• To dentine: 5-35MPa.
79. MANIPULATION
• TREATMENT OF TOOTH
• TREATMENT OF PROSTHESIS
METALLIC
PROSTHESIS
• GRIT BLASTING
• METAL PRIMER
• NATURAL OXIDE
RESIN VENEERS,INLAY
ONLAY,FPD
• GRIT BLASTING
• TREATED WITH
ADHESIVE
ALL CERAMIC
PROSTHESIS
• WATER SOLUBLE
TRY IN GELS
• ETCH AND SILANE
COATING IS APPLIED
80. Manipulation
• Ensure clean, dry area of tooth surface.
• condition with etchant.
• Prime.
• Bond.
• Remove excess cement immediately after prosthesis is
seated.
• Light cure if indicated, usually for no less than 40
seconds.
• The dual cure should not be used for any light
transmitting prosthesis thicker than 2.5mm (use
chemical cure for such).
86. Mineral trioxide aggregate (MTA)
• Mineral trioxide aggregate (MTA) was developed in early
1990s and has been successfully used for root perforation
repair, root end filling, and one-visit apexification.
• MTA is composed mainly of tricalcium silicate and
dicalcium silicate. When MTA is hydrated, calcium silicate
hydrate (CSH) and calcium hydroxide is formed.
• Formed calcium hydroxide interacts with the phosphate ion
in body fluid and form amorphous calcium phosphate
(ACP) which finally transforms into calcium deficient
hydroxyapatite (CDHA).
87. CONCLUSION
• So its readily apparent that no single type of
cement satisfies all ideal characteristics .
• It is prudent for the prosthodontist to have
several types available and according to the
situation should evaluate the type to be used.
Editor's Notes
Radio opacity min of 3mm of aluminium is desired
Heavier than the normal consistency is difficult to be expressed from underneath the restoration
The film thickness a well mixed non granular cement attains depends .
The type of restoration being cemented influences the ease of cement escaping from restoration example full cast crown
Rapid increase in viscosity with time demonstrates the need for prompt cementation after mixing delay may cause high viscosity means high consistency leading to incomplete cementation.
Acc to ada spec 96 the net ST based on a luting consistency is 2.5 to 8 min.(1st 60-90 sec is dedicated to mixing) as measured by standard indentor.
Advantages i. Only cement that is insoluble in oral fluids. ii. High strength. iii. Viscosity suitable for luting. iv. Various shades; color can be matched to the tooth. v. Dual cure. vi. Radio-opaque. vii. Easy to manipulate.
93. Disadvantages i. Disintegrates if used as a gap filler. ii. Self cured form is difficult to trim. iii. Expensive. iv. Irritation to pulp. v. Stains. vi. Poor wear if not highly filled.
