Pulp capping is a technique used in dental restorations to prevent the dental pulp from necrosis, after being exposed, or nearly exposed during a cavity preparation. When dental caries is removed from a tooth, all or most of the infected and softened enamel and dentin are removed. This can lead to the pulp of the tooth either being exposed or nearly exposed which causes pulpitis (inflammation). Pulpitis, in turn, can become irreversible, leading to pain and pulp necrosis, and necessitating either root canal treatment or extraction. The ultimate goal of pulp capping or stepwise caries removal is to protect a healthy dental pulp and avoid the need for root canal therapy.
To prevent the pulp from deteriorating when a dental restoration gets near the pulp, the dentist will place a small amount of a sedative dressing, such as calcium hydroxide or MTA. These materials, protect the pulp from noxious agents (heat, cold, bacteria) and stimulate the cell-rich zone of the pulp to lay down a bridge of reparative dentin. Dentin formation usually starts within 30 days of the pulp capping (there can be a delay in onset of dentin formation if the odontoblasts of the pulp are injured during cavity removal) and is largely completed by 130 days.
Two different types of pulp cap are distinguished. In direct pulp capping, the protective dressing is placed directly over an exposed pulp; and in indirect pulp capping, a thin layer of softened dentin, that if removed would expose the pulp, is left in place and the protective dressing is placed on top. A direct pulp cap is a one-stage procedure, whereas a stepwise caries removal is a two-stage procedure over about six months.
Video Pulp capping
Direct pulp cap
This technique is used when a pulpal exposure occurs, either due to caries extending to the pulp chamber, or accidentally, during caries removal. It is only feasible if the exposure is made through non infected dentin and there is no recent history of spontaneous pain (i.e. irreversible pulpitis) and a bacteria-tight seal can be applied. Once the exposure is made, the tooth is isolated from saliva to prevent contamination by use of a dental dam, if it was not already in place. The tooth is then washed and dried, and the protective material placed, followed finally by a dental restoration which gives a bacteria-tight seal to prevent infection. Since pulp capping is not always successful in maintaining the vitality of the pulp, the dentist will usually keep the status of the tooth under review for about 1 year after the procedure.
Maps Pulp capping
Indirect pulp cap (stepwise caries removal)
This technique is used when most of the decay has been removed from a deep cavity, but some softened dentin and decay remains over the pulp chamber that if removed would expose the pulp and trigger irreversible pulpitis. Instead, the dentist intentionally leaves the softened dentin/decay in place, and uses a layer of protective temporary material which promotes remineralization of the softened dentin over the pulp and the laying down of new layers of tertiary dentin in the pulp chamber. A temporary filling is used to keep the material in place, and about 6 months later, the cavity is re-opened and hopefully there is now enough sound dentin over the pulp (a "dentin bridge") that any residual softened dentin can be removed and a permanent filling can be placed. This method is also called "stepwise caries removal."
Materials
Calcium hydroxide cement
Calcium hydroxide (CaOH) is an organo-metallic cement that was introduced into dentistry in the early twentieth century and there have since been many advantages to this material described in much of the available literature. CaOH has a high antimicrobial activity which has been shown to be outstanding. In one experiment conducted by Stuart et al. (1991), bacteria-inoculated root canals of extracted human teeth were treated with CaOH for 1 hour against a control group with no treatment and the results yielded 64-100% reductions in all viable bacteria. CaOH also has a high pH and high solubility, thus it readily leaches into the surrounding tissues. This alkaline environment created around the cement has been suggested to give beneficial irritancy to pulpal tissues and stimulates dentine regeneration. One study further demonstrated that CaOH causes release of growth factors TGF-B1 and bioactive molecules from the dentine matrix which induces the formation of dentine bridges.
CaOH does however have significant disadvantages. The set cement has low compressive strength and cannot withstand or support condensation of a restoration. It is thus good practice to place a stronger separate lining material (e.g. glass ionomer or resin-modified glass ionomer) over CaOH before packing the final restorative material. CaOH cement is not adhesive to tooth tissues and thus does not provide a coronal seal. In pulp perfusion studies, CaOH has shown to insufficiently seal all dentinal tubules, and presence of tunnel defects (patent communications within reparative dentine connecting pulp and exposure sites) indicate a potential for microleakage when CaOH is used. It is suggested that an adhesive coronal restoration be used above the CaOH lining to provide adequate coronal seal. Because of its many advantageous properties and long-standing success in clinical use, it has been used as a control material in multiple experiments with pulp capping agents over the years and is considered the gold standard dental material for direct pulp capping to date.
Mineral Trioxide Aggregate
Mineral trioxide aggregate (MTA) is a recent development of the 1990s initially as a root canal sealer but has seen increased interest in its use as a direct pulp capping material. The material comprises a blend of tricalcium silicate, dicalcium silicate and tricalcium aluminate; bismuth oxide is added to give the cement radiopaque properties to aid radiological investigation. MTA has been shown to produce CaOH as a hydration product and maintains an extended duration of high pH in lab conditions. Similar to CaOH, this alkalinity potentially provides beneficial irritancy and stimulates dentine repair and regeneration. MTA has also demonstrated reliable and favourable healing outcomes on human teeth when used as a pulp cap on teeth diagnosed as nothing more severe than reversible pulpitis. There is also less coronal microleakage of MTA in one experiment comparing it to amalgam thus suggesting some tooth adhesion properties. MTA also comes in white and grey preparations which may aid visual identification clinically. Disadvantages have also been described for MTA. Grey MTA preparations can potentially cause tooth discolouration. MTA also takes a long time (up to 2 hours 45 minutes) to set completely thus preventing immediate restoration placement without mechanical disruption of the underlying MTA. It has been suggested that a pulp capped with MTA should be temporised to allow for the complete setting of MTA, and the patient to present at a second visit for placement of the permanent restoration. MTA also has for difficult handling properties and is a very expensive material, thus is less cost effective as compared to CaOH.
Although MTA shows great promise which is possibly attributed to its adhesive properties and ability to act as a source of CaOH release, the available literature and experimental studies of MTA is limited due to its recency. Studies that compare pulp capping abilities of MTA to CaOH in human teeth yielded generally equal and similarly successful healing outcomes at a histological level from both materials.
See also
- Pulpotomy
References
Source of the article : Wikipedia
0 Comments