Pulp protection in operative dentistry

 Introduction
 Causes of pulpal injury
 Remaining dentin thickness
 Pulp protection material
 Bases
 Properties
 Materials
 Liners
 Varnishes
 Sealers
 Dentin adhesives
 Pulp capping
 Direct pulp capping

 Indirect pulp capping
 Future of pulp capping materials
 Stressed pulp
 Conclusion
 References

 The restoration of compromised dental structure requires attention to function,
esthetics, and biology. Function and esthetics often can be restored to
satisfaction with current restorative materials and techniques.
 However, the biological requirements of dental restorations are poorly
understood. Since stimulated dental regeneration is still not a reality, dental
amalgam, resin-based composites, ceramics, and metals are used to restore
missing parts of teeth.
 Biologically, these materials are not expected to behave entirely like dentin or
enamel, but dental restorations should restore and protect the integrity of the
dentin– pulp complex. For many years, it was believed that restorative materials
themselves were toxic to the pulp.

 Based on that assumption, the use of bases and liners covering the vital dentin for
pulp protection was considered essential to the success of the restoration.
 This recommendation was based on studies that linked pulp reactions to the low
pH of dental materials .
 However, it is now believed that the main reason for the biological failure of
restorations is not related to pH or other attributes of the restorative material , but
rather to the poor ability of restorations to seal the tooth–restoration interface
leading to marginal leakage of bacteria and toxins .
 The role of bacterial infection on pulp pathologies was proposed in the mid-
1960s, and has been revisited in later years .

 During the last 20 years, a new approach to pulp protection has been proposed in
many countries, with more emphasis being placed on the ability of restorative
materials to prevent or neutralize bacterial penetration along the tooth–restoration
interface .

 In restorative dentistry, the following can be considered as the most common
causes of pulp injury, before, during, and after a restoration is placed:
 1. Presence of bacteria in the dentin–pulp complex.
 Cavitated carious lesions provide a niche for bacteria to aggregate and proliferate.
Once the lesion reaches the dentinoenamel junction (DEJ), bacteria and their
toxins can travel through the dentinal tubules and reach the pulp.
 Residual bacteria left after caries excavation, as well as bacteria reaching the
dentin–pulp complex through microleakage, can also cause pulp disease.

 2. Exposure of patent dentinal tubules.
 Patent dentinal tubules communicate directly to pulp cells. These can be present in
cervical areas of the tooth unprotected by enamel or cementum, and in
dentin/pulp exposures after trauma.
 Patent dentinal tubules might also be present in poorly sealed walls beneath
restorations, and contribute greatly to postoperative sensitivity.
 3. Depth of tooth preparation.
 The deeper the preparation, the greater is the chance for direct or indirect pulp
exposure.
 Deep preparations expose wider and more dentinal tubules per square millimeter
than shallow preparations, which can lead to pulp injury when dentin is not
properly sealed. However, preparation depth seems to be irrelevant for the pulp as
long as the preparation is not contaminated and the surface seal is maintained.

 Torstenson and Bra¨nnstro¨m histologically evaluated pulp responses to amalgam
restorations placed in teeth that would be extracted for orthodontic reasons.
 When contamination of the preparation was avoided, no inflammatory cells were
found in the pulp of most specimens, even when the remaining dentin thickness
(RDT) in the preparations was as little as 0.15 mm, and regardless of the use or not
of a pulp protection material.
 4. Dentin dehydration.
 When working with vital dentin, overdrying should be avoided. Dehydration of the
dentin surface by overdrying results in outward fluid flow, which in turn can result in
aspiration of odontoblast cells .
 5. Heat generation.

 Dentin has good insulative potential, but heat generation during tooth preparation,
light-curing, and finishing/polishing of a restoration can injure the pulp.
 It has been shown that a 5.51C increase in pulpal temperature result in a 15%
chance of necrosis, and an 111C increase result in 60% chance of necrosis .
 The dentin–pulp complex is capable of counteracting many of these insults.
However, the cumulative incidence of these and other injuries can reduce its
defense and repair potential.
 The age of the tooth also influences its response to injuries. In general, a younger
pulp is more resistant and can more readily offset irritants than an older pulp.

 On the other hand, a young tooth has a larger pulp chamber and more permeable
dentin structure than an old tooth, due to the deposition of secondary and
intratubular dentin that occurs with time.
 These biological factors must always be taken into consideration when selecting a
pulp protection technique or material.

 No material that can be placed in a tooth provides better protection for the pulp
than dentin.
 Dentin has excellent buffering capability to neutralize the effects of cariogenic
acids, and it insulates the pulp from temperature increases during cavity
preparation.
 The remaining dentinal thickness (RDT), from the depth of the cavity preparation
to the pulp, is the single most important factor in protecting the pulp from insult.
 In vitro studies have shown that a 0.5-mm thickness of dentin reduces the effect
of toxic substances on the pulp by 75% and a 1.0-mm thickness reduces the effect
of toxins by 90%.4 Little pulpal reaction occurs when there is an RDT of 2 mm or
more.

 The greatest impact on the pulp occurs when the RDT is no more than 0.25 to
0.30 mm. Conservation of remaining tooth structure is more important to pulpal
health than is replacement of lost tooth structure with a cavity liner or base.

 The selection of pulp protection material is a function of
 (1) the restorative material being used and
 (2) the RDT between the pulp and the pulpal or axial walls of the final tooth
preparation .
 Tooth preparations are often classified according to their depth as shallow or
deep.
 However, the concept of preparation depth is better applied when it relates to
the RDTas opposed to the distance from the cavosurface margin to the pulpal or
axial wall.

 Bases are used in relatively thick layers between the restorative material and the
tooth preparation.
 These have been traditionally used to provide thermal and electrical insulation,
mechanical pulp protection, and to create an ideal tooth preparation form in
deep preparations.
 Currently, bases are almost exclusively used only as internal buildups to block
undercuts in preparations for indirect inlays and onlays. Examples of bases are
zinc phosphate cement, zinc polycarboxylate cement, zinc oxide–eugenol cement,
and glass ionomer cements and derivatives.
 By virtue of their adhesive and fluoride-releasing properties, resinmodified glass
ionomer cements (e.g. Vitrebond, 3M ESPE; Fuji Lining LC, GC America, Alsip, IL,
USA) should be favored when a base is required.

 High Strength Bases
These are used to provide thermal protection for the pulp, as well as mechanical
support for the restoration.
Examples of high strength bases: zinc phosphate, zinc polycarboxylate, glass
ionomer and reinforced ZOE cements.
Some important properties of cements used as high strength bases are strength,
modulus of elasticity and thermal conductivity.
 Low Strength Bases
Low strength bases have minimum strength and low rigidity. Their main
function is to act as a barrier to irritating chemicals and to provide therapeutic
benefit to the pulp. Examples are: calcium hydroxide and zinc oxide eugenol.

 Thermal Properties
The base must provide thermal protection to the pulp. This property is important
especially when the tooth is restored with metallic restorations.
The thermal conductivity of most cement bases is similar to tooth structure and
is in the range of recognized insulators such as cork and asbestos.
For effective thermal protection the base should have minimal thickness of 0.75
mm. A thin wash of cement would not offer protection against thermal insults
through metallic restorations.
 Protection Against Chemical Insults
The cement base also serves as a barrier against penetration of irritating
constituents (e.g., acids, monomer, etc.) from restorative materials. Calcium
hydroxide and zinc oxide-eugenol are most effective for this especially in deep
(close to the pulp) cavities. Polycarboxylate and glass ionomer bases are also
used as chemical barriers in more moderate cavities.

 Therapeutic Effect
Some bases are used for their therapeutic benefit to the pulp. For example,
calcium hydroxide acts as a pulp capping agent and promotes the formation of
secondary dentin. Zinc oxide-eugenol has an obtundent effect on the pulp.
 Strength
The cement base must have sufficient strength to:
 Withstand the forces of condensation. Fracture or displacement of the base
permits the amalgam to penetrate the base and contact the dentin. Likewise,
in deep cavities the amalgam may be forced into the pulp through microscopic
exposures in the dentin.
 Withstand fracture or distortion under masticatory stresses transmitted t it through
the permanent restoration .Also the cement base should develop sufficient strength
rapidly in order to allow early condensation of amalgam. The minimum strength
requirement of a base is between 0.5 and 1.2 MPa.

 Zinc oxide–eugenol (ZOE) and zinc phosphate cements have been used for a
number of years as bases under a variety of restorative materials.
 Although both provide excellent thermal insulation and zinc phosphate cement
exhibits excellent physical properties, their use has diminished in recent years with
the growing question of their benefit to pulpal health and with the advent of
materials that release fluoride and adhere to dentin

 DESIRABLE PROPERTIES:
 chemical bond to tooth structure and fluoride release .Although fluoride release
from glass ionomer decreases with time, sustained release has been
demonstrated.

 The base is selected according to:
 Design of the cavity
 Type of permanent restorative material used of the pulp to the cavity walls.
 With amalgam, calcium hydroxide or zinc oxide-eugenol cement is usually
sufficient.
 In case of direct filling gold where the condensation pressure is higher, a stronger
cement is indicated as base.
 With resin restorations, calcium hydroxide is the material of choice, as zinc oxide-
eugenol cements interface with its polymerization. Glass ionomer cement can also
be used as base.

 Liners are more fluid than bases, and used in thin layers (approximately 0.5 mm).
Liners have been used traditionally to protect the dentin–pulp complex from the
potential toxic effects of restorative materials.
 Currently, liners are used to seal the dentinal tubules reducing dentin
permeability, as antibacterial agents, and as fluoride-releasing agents.
 Examples of liners are hard-set calcium hydroxide (CH) cements and glass
ionomer cements. Due to their biological properties (high pH, antibacterial,
stimulation of reparative dentin formation), CH cements (e.g. Dycal, Dentsply
Caulk, Milford, DE, USA; Life, Sybron Kerr, Orange, CA, USA) are indicated for
direct and indirect pulp caps, and when the RDT is judged to be less than 0.5 mm.

 CH cements do not adhere to dentin, have poor physical and mechanical
properties, and are extremely soluble.
 Therefore, they have to be covered by a layer of resin-modified glass ionomer
cement before the final restoration is placed.
 When the RDT is judged to be more than 0.5 mm, sealers and adhesives should
be used in lieu of liners.
 Like varnishes, cavity liners neither possess mechanical strength nor provide
any significant thermal insulation. The calcium hydroxide liners are soluble
and should not be applied at the margins of restorations. Fluoride compounds
are added to some cavity liners in an attempt to reduce the possibility of
secondary caries around permanent restorations or to reduce sensitivity.

 Like zinc phosphate, glass ionomer is quite acidic on initial mixing but tends to
neutralize within 24 hours.
 Pulpal response to both visible light–activated and conventional glassionomer
formulations has been shown to be favorable when not in direct pulpal contact,
likely because glass ionomer decreases interfacial bacterial penetration.
 The exact mechanism by which this is achieved is uncertain, but it may be due to
one or more of the following: fluoride release, initial low pH, chemical bond to
tooth structure (physically excluding bacteria), or release of a metal cation.
 Both visible light–activated and conventional glass-ionomer liners exhibit good
physical properties, with the conventional version exhibiting reduced interfacial
gap formation, a higher modulus of elasticity,and subsequently improved support
for amalgam restorations.

 Cavity liners are fluid in consistency and can be easily flowed or painted over
dentinal surfaces. The solvents evaporate to leave a thin film residue that
protects the pulp. The paste form is applied in the cavity and then light cured.

 Varnishes are synthetic or natural resins suspended in organic solvents. When
applied, varnishes form a non-uniform 5 mm-thin pellicle covering the tooth
preparation walls.
 For many years, copal resin varnishes have been used under amalgam
restorations and crowns to seal the dentin.
 Varnish use has decreased substantially due to their high solubility and poor
sealing ability , and because sealers are more advantageous than varnishes.

1. It reduces microleakage around the margins of newly placed amalgam
restorations, thereby reducing, postoperative sensitivity.
2. It reduces passage of irritants into the dentinal tubules from the overlying
restoration or base, e.g., silicate.
3. In amalgam restorations, they also prevent penetration of corrosion products
into the dentinal tubules, thus, minimizing tooth discoloration.
4. Varnish may be used as a surface coating over certain restorations to protect
them from dehydration or contact with oral fluids, e.g., silicate and glass
ionomer restorations.
5. Varnish may be applied on the surface of metallic restoration as a temporary
protection in cases of galvanic shock.

6. When electrosurgery is to be done adjacent to metallic restorations, varnish
applied over the metallic restorations serves as a temporary electrical insulator.
7. Fluoride containing varnishes release fluoride.

 SUPPLIED AS
 Liquid in dark colored bottles .
 Commercial Names Harvard lac, Chem Varnish, Secura, Fuji Varnish (GC)
 COMPOSITION
Natural gum such as copal, rosin or synthetic resin dissolved in an organic
solvent like alcohol, acetone, or ether. Medicinal agents such as chlorbutanol,
thymol and eugenol may be added. Some varnishes also contain fluorides.
 PROPERTIES
Varnishes neither possess mechanical strength nor provide thermal insulation
because of the thin film thickness. The film thickness ranges from 2 to 400 μm.
The solubility of dental varnishes is low; they are virtually insoluble in water.

 MANIPULATION
 The varnish may be applied by using a brush, wire loop or a small pledget of
cotton. Several thin layers are applied.
 Each layer is allowed to dry before applying the next one. When the first layer
dries, small pinholes develop.
 These voids are filled in by the succeeding varnish applications. The main
objective is to attain a uniform and continuous coating.
 PRECAUTIONS
1. Varnish solutions should be tightly capped immediately after use to prevent
loss of solvent by evaporation.
2. It should be applied in a thin consistency. Viscous varnish does not wet the
cavity walls properly. It should be thinned with an appropriate solvent.
3. Excess varnish should not be left on the margins of the restorations as it
prevents proper finishing of the margins of the restorations.

 CLINICAL CONSIDERATIONS
When placing a silicate restoration, the varnish should be confined to the dentin.
Varnish applied on the enamel inhibits the uptake of fluoride by the enamel.
 CONTRAINDICATIONS
1. Composite resins: The solvent in the varnish may react with the resin.
2. Glass ionomer: Varnish eliminates the potential for adhesion, if applied
between GIC and the cavity.
3. When therapeutic action is expected from the overlying cement, e.g., zinc
oxide-eugenol and calcium hydroxide.

 Fluoride varnishes are used to prevent or arrest tooth decay in smooth surfaces in
young children, especially when applied before age three as their teeth erupt.
 The taste does not appear to be offensive so is considered acceptable to young
children.
 The technique is well accepted by parents. It hardens on contact with saliva and
stays in contact with the teeth for several hours or days, but is not meant to
adhere permanently.
 Families should be told that their child can eat and drink afterward but they
should not brush the teeth until the next day, or at least 12 hours later, as it may
remove some of the varnish. Most protocols suggest two applications per year,
although some recommend up to four, with the first ones occurring fairly close
together or in the first 1-2 weeks.

 Trade names
Commonly used varnishes are Duraphat Pharmaceuticals, Inc), Duraflo
(Pharmascience, Inc), Fluor Protector (Ivoclar- Vivadent) and Cavity Shield (OMNII -
Oral Pharmaceuticals).
 COMPOSITION
 Composition varies depending on the particular brand. It contains concentrated
fluoride dissolved in an organic solvent. One varnish (Colgate Duraphat) contains
22,600 ppm (5%) Sodium fluoride. Another product Fluor Protector (Ivoclar-
Vivadent) contains 0.1% fluoride (fluorsilane) in ethyl acetate (65%)
isoamylpropionate (21%) and polyisocyanate (12%).

 Fluoride varnishes are painted on to the teeth using a special tiny brush. The
teeth are cleaned with a toothbrush first and then dried with a gauze square;
professional tooth cleaning with prophylactic paste is not indicated. Some
varnishes are colored for visualization during placement.
 CONTRAINDICATIONS
 Varnishes should not be used in cavitated carious lesions because the caries may
spread to other portions of the tooth, but can be used to remineralize white spot
lesions

 Sealers are aqueous solutions of resins (e.g. 2-hydroxyethylmethacrylate(HEMA)),
antibacterial agents (e.g. benzalkonium chloride, chlorhexidine), and/or
desensitizing agents (e.g. glutaraldehyde).
 Combinations of these compounds are found in specific commercial products
(e.g. Gluma Desensitizer, Heraeus Kulzer, Armonk, NY, USA, is an aqueous solution
of 35% HEMA and 5% glutaraldehyde).
 Sealers are compatible with a variety of restorative materials. Sealers are used in
place of varnishes under amalgam restorations and full crowns. Other examples
of sealers include HurriSeal (Beutlich Pharmaceuticals, Waukegan, IL, USA) and
Aqua-Prep F (Bisco, Inc., Schaumburg, IL, USA).

 The adhesion of restorations to dentin can be considered a truly new concept of
pulp protection, even though this technique was first described many years ago .
 Virtually all adhesives today bond simultaneously to enamel and dentin;
therefore, they should be more correctly referred to as dental adhesives.
 Dental adhesives provide pulp protection by making possible conservative tooth
preparations and by sealing out bacteria from the tooth–restoration interface.

 The most recent materials to be used as cavity sealers have a demonstrated
multisubstrate bonding ability that allows the restorative material to adhere to
tooth structure.
 Examples include adhesive bonding systems, resin luting cements, and glass-
ionomer luting cements. The benefits of using adhesive bonding systems to attach
resin composite materials to tooth structure are well documented and accepted.
 It is well established that acid etching will promote a reliable, durable bond to
enamel.Its mechanism of action (ie, the diffusion of polymerizable monomers into
porosities and channels established in enamel and dentin as a result of the
demineralizing action of acid) is well accepted.
 Bonding systems also provide a chemical bond between the unfilled resin of the
adhesive system and the resin composite. Enamel’s more consistent and highly
mineralized

 However, numerous studies have shown resin adhesives to provide a significant
reduction in leakage.
 While not unanimous, there is compelling evidence that adhesive resins used as
sealers reduce interfacial microleakage compared with either unsealed or varnish
sealed amalgam restorations when evaluated in the short term (24 hours to 14
days).
 The insoluble adhesive layer may act as a barrier to prevent amalgam corrosion
products from ultimately sealing the toothrestoration interface.
 As a result, the dentin bonding resins may potentially put the patient at greater
risk for marginal leakage and recurrent caries in the long term.
 Researchers have also noted the tendency of self-curing adhesive sealers used in
conjunction with amalgam restorations to spread to adjacent tooth surfaces,
potentially giving rise to periodontal irritation.

 Additional potential drawbacks to the use of adhesive sealers with amalgam
include pooling of resin, resulting in radiographic artifacts, and incorporation of
sealer into the amalgam during condensation, leading to significant loss of
amalgam strength.

 Pulp capping is defined as “endodontic treatment designed to maintain the vitality
of the endodontium.” Several favorable conditions must be present before
considering direct or indirect pulp capping:
• The tooth must have a vital pulp and no history of spontaneous pain.
• Pain elicited during pulp testing with a hot or cold stimulus should not linger after
stimulus removal.
• A periapical radiograph should show no evidence of a periradicular lesion of
endodontic origin.
• Bacteria must be excluded from the site by the restoration.

 RDT is directly related to odontoblast survival, reparative dentin formation is also
enhanced.
 In addition, avoiding pulp exposure means that there is less chance for infected
debris to be introduced into the pulp to cause an inflammatory reaction.
 Avoiding pulp exposure also means that there is no concern for hemorrhage from
the pulp, a factor that has been associated with decrease success rates in direct
pulp capping.

 Pulps can be exposed as a result of trauma, caries, or mechanical reasons. The
latter exposure is usually of iatrogenic origin.
 Direct pulp capping is an attempt to maintain pulpal vitality by placing a material
directly over the exposed pulp.
 It is hoped that this will allow the pulp to heal normally, regenerate reparative
dentin, and prevent the need for more extensive and expensive treatment, such
as root canal therapy.
 Studies have indicated that pulp capping is more likely to be successful if the
cause of the pulp exposure is mechanical rather than due to caries.

 A carious exposure will cause bacterial contamination of the pulp resulting in
inflammation and a pulp that is less able to respond and heal, whereas mechanical
exposure will likely cause less bacterial contamination and resulting inflammation.
 After a pulp has been exposed, it is important to control pulpal bleeding before
placing a pulp capping agent.
 Increased bleeding that is difficult to stop can compromise the success of the
procedure.
 This is likely due to one or both of two reasons. First, increased pulpal bleeding
may be indicative of a higher level of pulpal inflammation and therefore a reduced
capacity for pulpal healing.
 Second, the blood contamination of dentin adjacent to the exposure site may
compromise the seal required to exclude bacterial contamination of the exposed
pulp. Pulpal bleeding is normally controlled with a cotton pellet saturated in a
solution applied to the exposure site.

 A variety of solutions have been used in this situation. Water or saline are the most
benign to the pulp.
 Sodium hypochlorite, in concentrations ranging from 0.12% to 5.25%, is more
caustic to the pulp but is extremely effective at controlling bleeding and is very
effective at disinfecting the area.
 It has been used effectively in a number of studies and is likely the most commonly
used agent for controlling pulpal bleeding.
 Chlorhexidine solution is an effectual antibacterial but is not as effective for
controlling hemorrhage. Other solutions, such as those used to control gingival
bleeding during impression taking, have less evidence to support their use in pulp
capping, but short-term data seem to show few adverse effects on the pulp.
 One exception to this might be ferric sulfate, for which multiple clinical studies have
indicated increased postoperative pain when it was used in conjunction with pulp
capping

 It has been suggested that age may have an impact on the success or failure of
direct pulp capping, because older pulps have increased fibrosis and a decreased
blood supply and thus a decreased ability to mount an effective response to
invading microorganisms.
 The best chance for direct pulp capping to permit formation of a dentin bridge and
to maintain pulpal vitality is in the presence of the most ideal conditions.
 If a large number of bacteria from a caries lesion or exposure to the oral flora have
contaminated the pulp, the likelihood of regaining or maintaining a healthy pulp is
slight.
 The adverse consequences of bacterial contamination of the pulp have been well
documented. Ideally, direct pulp capping would be attempted only when a small
mechanical exposure of an otherwise healthy pulp occurs.

 A recent systematic review provided evidence that direct pulp capping of carious
exposures can be carried out successfully.
 However, the tooth should exhibit the favorable conditions noted previously. The
tooth must be isolated with rubber dam, and adequate hemostasis must be
achieved.
 The exposure should be covered with an appropriate pulp capping agent, and it
must be possible to restore the tooth with a well-sealed restoration that will
prevent subsequent bacterial contamination

 Zinc oxide–eugenol
 ZOE has been used in dentistry as a base, liner, cement, and provisional
restoration for decades.
 What is most appealing about ZOE as a potential pulp capping agent is its
antibacterial properties. ZOE releases eugenol in concentrations that are quite
cytotoxic.
 All teeth receiving ZOE pulp caps demonstrated chronic inflammation and a lack
of dentin bridging and pulpal healing 12 weeks after pulp capping.
 However, all control teeth that had been pulp capped with calcium hydroxide
showed healing within 4 weeks

 Glass ionomer and resin-modified glass ionomer demonstrate cytotoxicity when
in direct contact with cells, although not to the same degree as ZOE.
 Resin-modified glass-ionomer formulations tend to show greater cytotoxicity than
does the conventional glass-ionomer form.
 Glass ionomer and resin-modified glass ionomer also provide an excellent seal
against bacterial penetration, with good biocompatibility when not in direct
contact with the pulp.
 One study showed chronic inflammation and lack of dentin bridge formation up
to 300 days after direct pulp capping with a resin-modified glass ionomer. The
calcium hydroxide–treated control teeth demonstrated significantly better
healing

 As with ZOE, glass ionomer, and resin-modified glass ionomer, all components of
adhesive systems are cytotoxic to pulpal cells.
 Insufficiently cured adhesives exhibit greater cytotoxicity than adhesives that are
well polymerized due to the presence of unpolymerized components.
 First are the direct cytotoxic effects produced by adhesives on pulpal cells.
 Second is the difficulty in obtaining an adequate seal to protect against bacterial
contamination.
 This poor seal may be due to one or more reasons. Etchant and primer
components of adhesives are vasodilators, which can increase bleeding that
contaminates adjacent dentin and degrades adhesion.

 The increased moisture at the pulp capping site reduces polymerization of the
adhesive.
 This has the dual detrimental effects of decreasing adhesion and increasing the
availability of the unpolymerized and more toxiccomponents of the adhesive
 Finally, resin components reduce the pulp’s immune response, making it less
likely that the pulp will be able to defend itself against bacterial contamination.

 De Souza Costa and others concluded the following:
 (1 ) adhesives result in inferior pulp healing;
 (2 ) adhesives result in chronic inflammation, even in the absence of bacteria; and
 (3) inflammation is a poor environment for pulpal healing.
 Another issue in placing bonding resins directly on pulpal tissue is heat generation
from a quartz-tungsten-halogen (QTH) or a light-emitting diode (LED) curing light.
 An intrapulpal temperature increase of more than 20°F (11.2°C) has been shown to
cause irreversible damage in vivo.
 An increase of 18.2°C was found with a 10-second cure, and a 25.2°C increase was
detected with a 20-second cure.

 However, current LED lights demonstrate considerably higher light intensity
output and are capable of generating much greater heat. This can be a biologic
hazard to the pulp when little or no remaining dentin is present

 Calcium hydroxide was introduced to the dental profession in 1921 and has been
considered the gold standard of direct pulp capping materials for several decades
for a number of reasons.
 Calcium hydroxide has some disadvantages as well. The self-curing formulations
are highly soluble and are subject to dissolution over time, although it has been
noted that by the time the calcium hydroxide is lost due to dissolution, dentin
bridging has occurred.
 Calcium hydroxide has no inherent adhesive qualities and provides a poor seal.
 Another criticism noted of calcium hydroxide is the appearance of so-called tunnel
defects in reparative dentin formed beneath calcium hydroxide pulp caps.
 A tunnel defect has been described as a patency from the site of the exposure
through the reparative dentin to the pulp, sometimes with fibroblasts and
capillaries present within the defect.

 Calcium hydroxide possesse antibacterial properties, and this can minimize or
eliminate bacterial in the capped pulp.
 Traditionally, it has been believed that calcium hydroxide’s high pH causes
irritation of the pulpal tissue, which stimulates repair via some unknown
mechanism.
 In recent years, this “unknown mechanism” has been explained as the release of
bioactive molecules.

 Unset MTA is primarily calcium oxide in the form of tricalcium silicate, dicalcium
silicate, and tricalcium aluminate. Bismuth oxide is added for radiopacity. MTA is
considered a silicate cement rather than an oxide mixture, and so its
biocompatibility is due to its reaction products.
 Interestingly, the primary reaction product of MTA with water is calcium hydroxide.
As a result, many of the advantages and potential mechanisms of action for MTA
are similar to those for calcium hydroxide, including its antibacterial and
biocompatibility properties, high pH, radiopacity, and its ability to aid in the release
of bioactive dentin matrix proteins.
 A significant downside to MTA is the prolonged setting time of approximately 2
hours, 45 minutes.
 This requires that pulp capping with MTA either be done in a twostep procedure,
placing a provisional restoration to allow the MTA to set before placing the
restoration, or using a quick-setting liner to protect the MTA during definitive
restoration placement.

 A practice-based trial of pulp caps for mostly carious pulp exposures with 358
participants followed for up to 2 years, which also showed significantly better
outcomes with MTA compared with calcium hydroxide.
 A recent systematic review showed significantly better outcomes for MTA with an
indirect comparison between calcium hydroxide and MTA on the weighted pooled
success rate.
 There are several keys to direct pulp capping success: restricting pulp capping to
asymptomatic or mildly symptomatic teeth consistent with reversible pulpitis,
controlling bleeding, providing a bacterial seal at the exposure site, and providing a
well-sealed restoration following the pulp capping procedure.

Biodentine is a calcium-silicate based material, it has been used in various
clinical applications:
Advantages:
Biocompatible so no pulp inflammatory responses
Can be used wherever dentin is damaged
Outstanding sealing properties
Used as base or liner under composite restorations
Adequate compressive and flexural strength
Creates faster dentin bridges
Better properties than glass ionomer and calcium hydroxide
Radio opacity for following up

 Biodentine induces mineralization after its application, mineralization occurs in the
form of osteodentine that form reparative dentine.
 The ability to release Calcium is a key factor for successful pulp capping therapies
because of the action of calcium on differentiation, proliferation and mineralization
of pulp cells (osteoblasts, cementoblasts and odontoblasts
 Ca and Hydroxide ions enhance the activity of: ((Osteopontin, Alkaline
Phosphatase, Pyrophosphatase, Bone Morphogenetic Protein- 2(BMP-2) which
belongs to the TGF-β)) Which helps to maintain dentine mineralization and the
formation of dentine bridge.
 TGF-β1 is Responsible for early mineralization of reparative dentine that secrete
from the pulp cells.

 Histologically, Biodentine were showed complete dentinal bridge
formation (well localized pattern) and absence of inflammatory pulpal
response in contrast to Dycal that associated with tissue necrosis and
inflammation during initial period of placement

 Removal of carious tooth structure has been a basic step in dentistry.
 When the caries lesion is deep, every restorative dentist is faced with the decision
as to the best way to proceed: Is it better to remove all carious dentin regardless of
pulpal consequences or to stop short to avoid pulp exposure? When practitioners
in a dental practice-based research network were given a hypothetical scenario
that involved this question, only 17% responded that they would stop, leave the
remaining carious dentin in place, and restore the tooth.
 This procedure, in which carious dentin is allowed to remain adjacent to a vital
pulp—rather than risk pulp exposure—and is covered with a cavity sealer or liner
prior to restoration is termed an indirect pulp capping procedure, or indirect pulp
treatment .
 Pierre Fauchard first suggested indirect pulp capping 200 years ago

 The evidence regarding indirect pulp capping stands in contrast to the response of
the practitioners, however.
 Several studies show that restored teeth with partial caries removal have equal
success compared with restored teeth with complete caries removal.
 A number of studies have evaluated the fate of caries lesions in which partial
caries removal was accomplished.
 Typically, an initial clinical and microbiologic assessment of the caries lesion is
carried out, partial caries removal is accomplished, and a sealer or liner and
restoration is placed for a period of 4 to 12 months before the tooth is reentered
and reassessed. Invariably, these studies find that
 (1) the lesion color has changed from light brown to dark brown,
 (2) the tissue consistency has changed from soft and wet to hard and dry,

 (3) Streptococcus mutans and Lactobacillus have been significantly reduced to a
limited number or even zero viable organisms, and
 (4) the radiographs show either no change or even a decrease in the radiolucent
zone.
 It is known that inflammation is present when active caries is adjacent to the pulp,
but there is little to no inflammation if caries is arrested.
 The type of liner is less important to success than the placement of a well-sealed
restoration.
 In addition, partial removal of carious dentin significantly reduces the chance of
pulp exposure during caries excavation.
 This is very important, because pulp exposures result in more pulp injury,
inflammation, and poorer prognosis for pulp vitality than when pulp exposure is
avoided.

 Two thorough systematic reviews confirmed the scientific validity of indirect pulp
capping and concluded the following:
 (1) partial removal of carious dentin reduced the risk of pulp exposure by 98%
compared with complete caries excavation in teeth with deep caries lesions;
 (2) there is no evidence that partial removal of carious dentin is detrimental in
terms of signs, symptoms, pulpitis occurrence, or restoration longevity; and
 ( 3 ) there is substantial evidence that complete removal of carious dentin is not
needed for success provided the restoration is well sealed.
 An indirect pulp capping procedure should be considered when there is a
radiographically or clinically evident deep caries lesion encroaching on the pulp and
the tooth has no history of spontaneous pain and responds normally to vitality
tests.
 Pulp exposure must be avoided; if it occurs, it should be regarded as an iatrogenic
event

 A direct pulp capping procedure should be necessary only if the operator
inadvertently exposes the pulp in attempting an indirect pulp capping procedure.
 With a deep caries lesion, the indirect pulp capping procedure is always preferred to
a direct pulp capping procedure.
 For indirect pulp capping , after the initial entry into the carious dentin , a spoon
excavator or large round bur, rotating very slowly in a low-speed handpiece, should
be used to excavate the caries-softened dentin.
 Demineralized dentin not near the pulp should be completely removed, leaving
hard, sound dentin.
 As the excavation of carious dentin nears the pulp, caution must be exercised to
avoid pulp exposure.

 A spoon excavator may aid in tactile detection of softened dentin.
 The wet (soft, amorphous) carious dentin should be removed; as the pulp is
approached, the dry, fibrous, demineralized dentin that offers some moderate
resistance to gentle scraping with a spoon excavator should be allowed to remain.
 Caries-disclosing dyes may be used to assist in excavation of carious dentin .
 Studies have demonstrated the benefit of these dyes to aid in identification and
removal of demineralized dentin and to greatly reduce remaining viable bacteria.
 It must be recognized that the dyes stain not only demineralized dentin but also
anything porous, such as debris that may have been left in the cavity preparation.
 In addition, noncarious deep dentin will absorb the dye because of the increased
number and size of the dentinal tubules in deep dentin; if this dye-stained sound
dentin is removed, pulp exposure will result.

 There has been concern that, when using a dentin bonding system, the previous use of
caries-disclosing dyes can reduce the strength of the bond to dentin and increase
microleakage at the interface of the bonded restoration with the wall of the cavity.
 However, the preponderance of evidence indicates that neither of these should be a
concern.
 In the indirect procedure, all carious dentin is removed except for the last portion of
firm, leathery carious dentin immediately overlying the pulp.
 At this point, a calcium hydroxide liner is placed over the demineralized area of dentin .
 Placement of calcium hydroxide over this layer of leathery dentin has been shown to
virtually eliminate all remaining bacteria and to render the residual carious dentin
operationally sterile.
 Then a layer of resin-modified glass ionomer is placed, covering the calcium hydroxide
and extending onto sound dentin on the periphery to provide a seal .

 Resin-modified glass ionomer alone (without calcium hydroxide as an initial layer) is
also effective at providing favorable clinical and microbiologic changes when used as
a liner on remaining caries.
 If any vital bacteria remain, a well-sealed restoration should isolate them from life-
sustaining substrate and prevent further acid production, thereby arresting the
caries theprocess.
 These facts argue against a two-step procedure in which the tooth is reentered for
the purpose of excavating the remaining acid-affected dentin to confirm reparative
dentin formation.
 Bacterial levels in caries lesions are reduced most significantly after the initial caries
excavation and liner placement, with little additional benefit from subsequent
excavation.
 In addition, a second caries removal procedure risks creating a pulp exposure and
causing further traumatic insult to the pulp.

 A glass-ionomer liner should be placed over the calcium hydroxide liner to
improve strength during amalgam condensation and to enhance the seal . The
definitive restoration should be placed to minimize microleakage at the interface
of the restoration with the cavity-preparation walls

A number of materials are being investigated for future use as direct pulp capping
agents. Hydroxyapatite elicited a better pulpal response than calcium hydroxide in
one animal study because the hydroxyapatite acted as a scaffold for dentin
formation. It seems that the most promising research area in pulp capping likely
relates to placing materials that either contain bioactive molecules or are capable of
releasing them from the dentin matrix. Growth factors such as BMP and TGF-β1
offer intriguing potential as initiators and/or mediators in pulpal repair. In an
animal study, BMP and bone sialoprotein (BSP) were more effective for inducing
reparative dentin than was calcium hydroxide.Another animal study showed that
TGF-β1 was able to stimulate pulpal stem cells to differentiate into odontoblast-like
cells that produced reparative dentin

 T he term “stressed pulp” describes a vital dental pulp that has been subjected to
repeated damage, including operative trauma, accidents, or other pathologic
changes. The stressed pulp condition is a clinical concept and not a histologic
entity.

Operative procedures and materials that cause pulpal injury and may lead to pulpal
stress include the following:
 Deep tooth preparation (where less than 2 mm of remaining dentin covers the
pulp)
 High-speed tooth cutting without coolant
 Application of topical medications on cavity preparations’
 Continuous air-drying of preparation
 Cement with high acidity
 Direct pulp capping
 Local anesthesia of long duration (while full-crown preparation is made)
 Unlilled resin restoration
 Unbased restoration allowing for thermal conductivity

The following diseases, conditions, and treatment cause pulpal injury and may lead
to pulpal stress:
 Chronic bruxism
 Chronic caries
 Chronic periodontal disease’
 Chronic trauma from occlusion’
 Chronic occlusal attrition and erosion
 Cracks in tooth structure
 Radiation therapy
 Systemic diseases of oral manifestation
 Diabetes, vitamin C deficiency, leukemia, endocrine disturbances

The ability of the pulp to recover from pathologic and operative trauma is related to:
 Type of injury. Mild injury is believed to be of no significance, and repair can be
expected.
 Duration of injury. A primary injury of short duration provides the best chance for
recovery.
 Thickness of remaining dentin. Remaining dentin between the cavity floor or
crown preparation and the pulp is necessary to protect the pulp. If the remaining
dentin is less than 2 mm thick,4 trauma to the pulp becomes more damaging and
the recovery chances are reduced.
 Physiologic age of the tooth. The pulp chamber and apical foramen size should be
large enough to allow adequate vascular flow to the tooth. A receded pulp
chamber or pulp chamber filled with calcification stones or reparative dentin may
not have a good reparative potential due to its deprivation of vascular and cellular
elements.“’
 Host factors. Patient age and systemic health play an important role in pulp
recovery potentials. Young, healthy patients have better healing responses

 Endodontics should be considered strongly before beginning restorative therapy,
orthodontics, or other traumatic procedures on teeth with stressed pulps.

 When bacteria and bacterial byproducts are completely excavated from a non-
exposed tooth preparation, and a restoration that prevents the leakage of
bacteria and bacterial byproducts into the dentin–pulp complex is placed, pulp
protection has been achieved.
 When the pulp has been irreversibly compromised by preexisting conditions (e.g.
bacterial infection, trauma, etc.), no pulp protection technique can predictably
achieve a good pulpal prognosis.
 Pulp protection using bases and liners sometimes is necessary due to the
inability of the existing restorative materials and techniques to provide a long-
term hermetic seal around restorations.
 All restored teeth, but especially those with deep restorations, must be followed
up with vitality tests and radiographs to confirm maintenance of pulp vitality.

 SUMMIT 4 TH EDITION
 Bioactive and Biomimetic Restorative Materials: A Comprehensive Review. Part I
& II STEVEN R. JEFFERIES, MS, DDS, PhD* Vol 26 • No 1 • 14–26 • 2014 Journal of
Esthetic and Restorative Dentistry
 JOHN J MANAPALLI
 A. (2014, January 12). Recent Advances in Pulp Capping Materials: An Overview.
Retrieved January 8, 2014
 Current restorative concepts of pulp protection ANDRE´ V. RITTER & EDWARD J.
SWIFT JR.

Pulp protection in operative dentistry

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