Pulp capping

Visible light activated resin compositions containing calcium hydroxide have been made available as cavity lining materials (99) for pulp capping and pulpotomy, and may offer in other appHcations an alternative to the calcium sahcylate type cements. 

Granath, L. E. (1982). Pulp capping materials. In Smith, D. C. Williams,... 

Pastes of calcium hydroxide with water have been used as pulp-capping materials for many years and it is the material of choice for this application (Granath, 1982). Its favourable tissue responses have been known for many years (Zander, 1939). It has a healing effect, for it induces the formation of hard tissues of reparative dentine when pulp has been exposed (Eidelman, Finn Koulourides, 1965). This action seems to be associated with its high alkalinity (pH 12-5) and consequent bactericidal and proteinlysing effect (Fisher, 1977). 

These cements are the materials of choice for pulp capping (a wound dressing for covering an exposed or surgically treated pulp). They are superior to zinc oxide eugenol cements for this purpose (Mjor, 1963 Paterson, 1976). 

McWalter, G. K., El-Kafrawy, A. H. Mitchell, D. F. (1976). Long term study of pulp capping in monkeys with three agents. Journal of the American Dental Association, 93, 105-111. 

Tziafas, D. 1989. Experimental bacterial anachoresis in dog dental pulps capped with calcium hydroxyde. J. Endodont. 15 591-595. 

Frank R.M., Wiedemann R, Hemmerle L, and Freymann M. 1991. Pulp capping with synthetic hydroxyapatite in human premolars. /. Appl. Biomater. 2 243-250. 

The tooth pulp can become exposed by a variety of processes, including deep caries, trauma or accidentally during cavity preparation in the dental chair [60]. The consequences can be severe, and include pain, infection and necrosis. When the pulp is exposed, steps need to be taken to manage the situation, and these involve either pulp capping with an appropriate material [60,61] or removal of the pulp followed by sealing of the tooth roots. In the present section of the chapter, we consider briefly materials for the first of these options, pulp capping. 

When hardened. Biodentine shows good biocompatibihty with the oral tissues and, in particular, exerts minimal influence on cells of the adjacent pulp. Some loss of cell viability has been reported, but this has been attributed to apoptosis and necrosis, rather than the toxicity of the material [71]. In one study of the performance of Biodentine, it was found that the material caused complete dentinal bridge formation in molars while creating no inflammatory response on the cells of the pulp [72]. Both of these features suggest that this material has promise for application in pulp capping. Its ability to promote regeneration of the hard tissue is particularly noteworthy, and will be considered in more detail in Chapter 9. 

T.J. Hilton, Keys to clinical success with pulp capping a review of the literature. Open Dent 34 (2009) 615-625. 

L.W. Stockton, Vital pulp capping a worthwhile proeedure, J. Can. Dent. Assoc. 65 (1999) 328-331. 

U. Schroder, Effects of calcium hydroxide-containing pulp-capping agents on pulp cell migration, prohferation, and differentiation, J. Dent Res. 64 (1985) 541-548. 

T.R. Pitt Eord, G.J. Roberts, Immediate and delayed direet pulp capping with the use of a new visible hght cured calcium hydroxide preparation. Oral Surg. Oral Med. Oral Pathol. 71 (1991)338-342. 

A. Nowicka, M. Lipska, M. Parafiniuk, D. Lichota, J. Buczkowska-Radlinska, Response of human dental pulp capped with biodentine and mineral trioxide aggregate, J. Endod. 39 (2013) 743-747. 

Alternatively the pulp may be saved by the process of pulp capping. This involves placing some sort of material over the pulp to protect it and maintain its viability so that more extreme treatment (extraction or endodontic therapy) can be avoided [1]. Two possible approaches are available, namely direct pulp capping, in which a bioactive material is placed directly over the exposed pulp, and indirect pulp capping, in which a cavity liner or sealant material is placed over a residual thin layer of dentine, which may be sound or carious. In the latter approach, the pulp has not been exposed, but it is at risk of becoming so either by the progress of the residual caries or by the process of tooth preparation. 

As well as adverse effects of certain types of repair material, pulp can be affected by the entry of bacteria. In fact, this is the main reason for inflammation of the pulp and necrosis. In the presence of bacterial infection, seriously damaging reactions can occur resulting in inflammation and loss of vitality of the pulp [8-10]. In applying any type of pulp capping material, the critical feature needed to aisure survival of the pulp is creation of an adequate seal [11]. A proper durable seal is necessary to prevent invasion of bacteria, and to protect the pulp from the damaging consequences of bacterial infection [1]. 

Direct pulp capping involves placing a pulp capping material directly over the exposed pulp with the aim of promoting pulp healing and the generation of reparative dentine [1], When this procedure is applied successfully, it eliminates the need for alternative, more invasive treatments. 

There is evidence that the pulp is more likely to survive if exposure occurs by accident during tooth preparation rather than due to the progression of caries [11,12], This is because caries penetration is inevitably associated with bacterial invasion, and therefore results in infection and inflammation of the pulp [10], By contrast, exposure due to a mechanical misadventure during tooth preparation does not necessarily result in bacterial invasion. Consequently, the exposed pulp does not become infected or inflamed. As a result, teeth repaired by direct pulp capping following this type of exposure are generally better able to survive with their pulp intact than those whose pulps become exposed due to advancing caries [11]. 

The removal of caries is essential when repairing a tooth damaged by decay. However, when caries is deep this may present a problem, as continued caries removal to prepare the cavity fully may lead to exposure of the pulp. Rather than exposing the pulp in this way, with the risks involved in such a procedure, an alternative approach is to leave the caries-affected demineralized dentine in the region directly adjacent to the pulp and to cover the whole of the affected zone with a cavity liner. This procedure is termed indirect pulp capping [1], and it has been shown to be as successful as restoring teeth conventionally with complete caries removal [26-28]. 

As well as being used for direct and indirect pulp capping, calcium hydroxide materials are recommended for nse in deep cavities. This is similar to their use in indirect pulp capping, but implies that all of the carious dentine has been removed, leaving behind a thin layer of sonnd caries-free dentine. Even in this circumstance, the high alkalinity of calcinm hydroxide materials is able to stimulate further dentine formation [41,43,44]. Their application where remaining sonnd dentine is thin will ensure that it does not remain thin. Instead, it will thicken in sitn nnder the influence of the calcium hydroxide to form an improved layer of dentine that is better able to protect the pulp from diffusion of monomers from repair materials or from the effects of bacterial penetration. This process takes time, with typically approximately 2 months time being need to form 0.1 mm of reparative dentine. 

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