Current concepts of pulp protection



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Current concepts of pulp protection

Dental pulp consists of vascular connective tissue contained within the rigid dentin walls. It is the principle source of pain within the mouth and also a major site of attention in endodontics and restorative treatment.

Vital pulp therapy is broadly defined as treatment initiated to preserve and maintain pulp tissue in a healthy state, tissue that has been compromised by caries, trauma, or restorative procedures. The objective is to stimulate the formation of reparative dentin to retain the tooth as a functional unit. This is particularly important in the young adult tooth, where apical root development may be incomplete.

Indications for Vital Pulp Therapy

Vital pulp therapy is indicated whenever the remaining pulp exhibits reversible pulpitis and can be selectively induced to produce a reparative barrier that protects the tissue from microbial challenges.



Vital Pulp Therapy Materials

Ideal requirement of pulp capping material, may include the following characteristics:



  1. Stimulate reparative dentin formation

  2. Maintain pulpal vitality

  3. Release fluoride to prevent secondary caries

  4. Bactericidal or bacteriostatic

  5. Adhere to dentin

  6. Adhere to restorative material

  7. Resist forces during restoration placement

  8. Must resist forces under restoration during lifetime of restoration

  9. Sterile

  10. Radiopaque

  11. Provide bacterial seal

The materials most commonly used are:

CALCIUM HYDROXIDE

This material, long considered the ‘‘benchmark’’ for vital pulp therapy materials, has been shown to have some desirable properties, but long term study outcomes have been variable. Beneficial characteristics include a bactericidal component owing to its high alkaline pH and the irritation of pulp tissue that stimulates pulpal defense and repair. Although calcium hydroxide has been shown to be clinically effective over time, it produces a superficial layer of coagulation necrosis. The low-grade irritation of this layer induces the formation of a hard tissue barrier. Conversely, calcium hydroxide Ca(OH)2 has been shown to be cytotoxic in cell cultures, does not exclusively stimulate reparative dentin formation, shows poor marginal adaptation to dentin, it can degrade and dissolve beneath restorations, and it can also suffer interfacial failure upon amalgam condensation, the material fails to provide a long-term seal against microleakage when used as a pulp capping agent which can provide microorganisms with a pathway for penetration into pulpal tissue.



MINERAL TRIOXIDE AGGREGATE (MTA)

MTA was introduced to endodontics by Lee et al. in the early 1990s. This bioactive silicate cement was originally composed of tricalcium silicate, tricalcium aluminate, tricalcium oxide, silicate oxide, and other mineral oxides. Originally a gray powder, 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 noticeable bridge has formed subjacent to MTA.B,A comparable bridge under calcium hydroxide after 2 weeks.C,A 4-week specimen with MTA shows excellent bridge formation.D,Consistently, the bridge formation under calcium hydroxide lagged behind MTA; an example of bridge formation under calcium hydroxide 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 direct pulp capping material in adult teeth or as an agent in partial or complete pulpotomy in primary teeth:


  1. MTA, unlike calcium hydroxide, has been shown to induce a hard tissue barrier without inflammation.

  2. It set in the presence of blood and moisture.

  3. It exhibits a superior marginal adaptation and is nonabsorbabale,

  4. When it cures in the presence of calcium ions and tissue fluids, it forms a reactionary layer at the dentin interface resembling hydroxyapatite in structure.

  5. Biocompatible characteristics include a sustained alkaline pH after curing, small particle size, and a slow release of calcium ions.

  6. MTA induces pulpal cell proliferation, and promotes hard tissue formation.

The high alkalinity of MTA and its calcium release and sustained pH at 12.5 is most likely responsible for preventing any further microbial growth of residual microorganisms left after caries excavation. The high pH also extracts growth factors from adjacent dentin thought to be responsible for promoting dentinal bridging.

Indications:

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Examples of MTA material



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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. Calcium silicate based materials have gained popularity in recent years due to their resemblance to mineral trioxide aggregate (MTA) and their applicability in cases where MTA is indicated. This material “Biodentine” became commercially available in 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.

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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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