Current concepts of pulp protection
Dental pulp consists of vascular connective tissue containedwithin the rigid dentin walls. It is the principle source of painwithin the mouth and also a major site of attention inendodontics and restorative treatment.
Vital pulp therapy is broadly defined as treatmentinitiated to preserve and maintain pulp tissue in ahealthy state, tissue that has been compromised by caries, trauma, or restorative procedures. The objective is tostimulate the formation of reparative dentin to retain thetooth as a functional unit. Thisisparticularlyimportantin the young adult tooth, where apical root developmentmay be incomplete.
Indications for Vital Pulp Therapy
Vital pulp therapy is indicated whenever the remainingpulp exhibits reversible pulpitis and can be selectivelyinduced to produce a reparative barrier that protects thetissue from microbial challenges.
Vital Pulp Therapy Materials
Ideal requirement of pulp capping material, may include the following characteristics:
- Stimulate reparative dentin formation
- Maintain pulpal vitality
- Release fluoride to prevent secondary caries
- Bactericidal or bacteriostatic
- Adhere to dentin
- Adhere to restorative material
- Resist forces during restoration placement
- Must resist forces under restoration during lifetimeof restoration
- Sterile
- Radiopaque
- Provide bacterial seal
The materials most commonly used are:
CALCIUM HYDROXIDE
This material, long considered the ‘‘benchmark’’ forvital pulp therapy materials, has beenshown to have some desirable properties, but longterm study outcomes have been variable.Beneficial characteristics include a bactericidal componentowing to its high alkaline pH and the irritation ofpulp tissue that stimulates pulpal defense and repair.Although calcium hydroxidehas been shown to be clinically effective over time, it produces a superficial layer of coagulation necrosis. Thelow-grade irritation of this layer induces the formationof a hard tissue barrier.Conversely, calcium hydroxideCa(OH)2has been shown to be cytotoxicin cell cultures, does not exclusively stimulate reparative dentin formation, shows poor marginal adaptation to dentin, it can degrade and dissolve beneathrestorations, and it can also suffer interfacial failure upon amalgam condensation, the material fails toprovide a long-term seal against microleakage whenused as a pulp capping agent which can provide microorganismswith a pathway for penetration into pulpal tissue.
MINERAL TRIOXIDE AGGREGATE (MTA)
MTA was introduced to endodontics by Lee et al. inthe early 1990s.This bioactive silicate cement wasoriginally composed of tricalcium silicate, tricalciumaluminate, tricalcium oxide, silicate oxide, and othermineral oxides. Originally a graypowder, white MTA was produced for esthetic reasons.
Comparison of dentin bridge formation using mineral trioxide aggregate (MTA) or calcium hydroxide in dog pulps.A,After 1 week, a noticeablebridge has formed subjacent to MTA.B,A comparable bridge under calcium hydroxide after 2 weeks.C,A 4-week specimen with MTA shows excellentbridge formation.D,Consistently, the bridge formation under calcium hydroxide lagged behind MTA; an example of bridge formation under calciumhydroxide after 8 weeks. CH = calcium hydroxide; DB = dentin bridge; MTA = mineral trioxide aggregate.
The cement exhibits many favorable characteristics,which make it a superior material when used as a directpulp capping material in adult teeth or as an agent inpartial or complete pulpotomy in primary teeth:
- MTA, unlike calcium hydroxide, has been shown to induce a hard tissue barrier without inflammation.
- It set in the presence of blood and moisture.
- It exhibits a superiormarginal adaptation and is nonabsorbabale,
- When it cures in the presence of calcium ions and tissuefluids, it forms a reactionary layer at the dentininterface resembling hydroxyapatite in structure.
- Biocompatible characteristics include a sustainedalkaline pH after curing, small particle size, and a slowrelease of calcium ions.
- MTA inducespulpal cell proliferation, and promotes hard tissue formation.
The high alkalinity of MTA and its calcium release and sustained pH at 12.5 is most likelyresponsible for preventing any further microbial growthof residual microorganisms left after caries excavation.The high pH also extracts growth factors from adjacentdentin thought to be responsible for promoting dentinal bridging.
Indications:
Examples of MTA material
BIODENTINE
Biodentine is a calcium-silicate based material that has drawn attention in recent years and has been advocated to be used in various clinical applications, such as root perforations, apexification, resorptions, retrograde fillings, pulp capping procedures, and dentine replacement.Calciumsilicatebasedmaterialshavegainedpopularityinrecent years due to their resemblance to mineral trioxideaggregate (MTA) and their applicability in cases where MTAis indicated.This material “Biodentine” became commercially availablein 2009 by Septodont company.
Indications:
Biodentine™ is a material offering bioactivity and outstanding sealing properties to fully replace dentine, both in the crown and in the root with unique benefits:
1 - Preservation of pulp vitality:
- Absence of post-operative sensitivity: high biocompatibility reducing the risk of pulp or tissue reaction
• Bioactive: remineralisation of dentine for unique pulp healing properties
• Formation of reactionary dentine and dentine bridges
• Pulp healing promotion after pulp exposure: reversible pulpitis, trauma or iatrogenic exposure
2 - Prevention of clinical failures:
• Long lasting sealing properties: mineral tags in the dentine tubules combined with high dimensional stability over time
• Less risk of bacterial percolation: outstanding microleakage resistance
• Absence of post-operative sensitivity: no shrinkage
• No conditioning or bonding: natural mechanical anchorage in dentine tubules
3 - Ultimate dentine substitute: Biodentin can replace dentin with the same mechanical properties.
• Easy handling for optimised clinical use
• Superior radiopacity for clear short and long term follow-up
• Comparable to human dentine: similar mechanical behaviour
LASERS
The word LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.Laser was first introduced by Maiman in 1960, after which it was used in many field of medicine and dentistry. Lasers can be used nearly in all fields of dentistry.The most frequently used lasers in dentistry, either for basic research or clinical application, are the Carbon dioxide (CO2), the Er:YAG (Erbium-Yttrium- Aluminum - Garnet) and the Er,Cr:YSGG (Erbium-Chromium-Yttrium-ScandiumGallium-Garnet) , Holmium yttrium-aluminium garnet laser (Ho:YAG), Neodymium yettrium aluminum garnet (Nd:YAG)laser, the Diodes, Argon laser(Ar), and the Excimer lasers.
Laser can be used for direct and indirect pulp capping with the following advantages:
1-Unlike mechanical instrumentation, the erbium laser produces minimal temperature increase because the tooth is air/water-cooled, while being bactericidal and productive of hemostasis. And may even decrease when working with water spray cooling.
2-The laser does not produce dentinal chips like rotary instruments, thus minimizing the chances of bacterial recontamination
3-There is no mechanical insult to the nerve, such as vibration, smearing or heat, which is the case when using drills.The infected dentine is thus removed completely
4-laser supported direct pulp capping has proven effectiveness by its capacity to stimulate reparative dentine formation by pulp cells
5- The laser minimizes the formation of hematoma between the pulp tissue and the calcium hydroxide dressing allowing a close contact between the dressing and the exposed pulp.
6-pain reduction
7- The use of the Erbium lasers laser allows cavity preparation to be completed with only one instrument, in contrast to the alternate use of high- and low-speed rotary instruments
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