Direct pulp capping
Till Dammaschke reviews a new bioactive cement.
Biodentine is a new bioactive cement with dentin-like mechanical properties, which can be used as a dentin substitute on crowns and roots. It has a positive effect on vital pulp cells and stimulates tertiary dentin formation. In direct contact with vital pulp tissue it also promotes the formation of reparative dentin. This prompted its use for direct pulp capping after iatrogenic pulp exposure at tooth 15 in a 22-year-old male patient. First the entire cavity was filled with Biodentine. Three months later the cement was reduced to a base to replace the dentin layer and a composite filling was placed to replace the enamel layer. At the follow-up visit at six months the tooth was clinically normal and tested positive for sensitivity and negative for percussion. The dental film showed the apical region without any pathological findings.
Due to its improved material properties, Biodentine is an interesting alternative to conventional calcium hydroxide-based materials. It offers advantages for direct pulp capping and, in properly selected cases, may contribute to the long-term maintenance of tooth vitality.
For many decades calcium hydroxide has been the standard material for maintaining pulp vitality. Both clinically and histologically it has been found to produce satisfactory results in indirect and direct pulp capping, because it is capable of stimulating the formation of tertiary dentin by the pulp. In contact with vital pulp tissue it contributes to the formation of reparative dentin, a special variant of tertiary dentin, which seals exposures by newly formed hard tissue. This has been documented by basic research and clinical studies with reported success rates in excess of 80 per cent for direct pulp capping. Currently, calcium hydroxide products are the best documented and most reliable materials for direct pulp capping and serve as the 'gold standard' against which new materials have to be tested.
Nevertheless, calcium hydroxide has some drawbacks. Poor bonding to dentin, material resorption and mechanical instability are among them. As a result, calcium hydroxide does not prevent microleakage in the long run. The porosities ('tunnel defects') of the newly formed hard tissue may act as a portal of entry for microorganisms. These may cause secondary inflammation of the pulp tissue and are thought to be responsible for failed maintenance of tooth vitality. In addition, the high pH (12.5) of calcium hydroxide suspensions causes liquefaction necrosis at the surface of the pulp tissue.
A new bioactive cement, Biodentine (Septodont), was recently launched on the dental market as a dentin substitute. It shares its indications and mode of action with calcium hydroxide, but does not have its drawbacks. Biodentine consists of a powder in a capsule and liquid in a pipette. The powder mainly contains tricalcium and dicalcium silicate, the principal component of Portland cement, as well as calcium carbonate. Zirconium dioxide serves as contrast medium. The liquid consists of calcium chloride in aqueous solution with an admixture of polycarboxylate. The powder is mixed with the liquid in a capsule in the triturator for 30 seconds. Once mixed, Biodentine sets in about 12 minutes. During the setting of the cement calcium hydroxide is formed. The consistency of Biodentine is similar to that of phosphate cement.
Biodentine can be used on crowns and roots. Its crown uses include pulp protection, temporary closure, deep caries management, cervical filling, direct and indirect pulp capping and pulpotomy. On roots it has a place in managing perforations of root canals or the pulp floor, internal and external resorption, apexification and retrograde root canal obturation.
In summary, Biodentine is a dentin substitute base and a cement for maintaining pulp vitality and stimulating hard tissue formation, the formation of reactive or reparative (tertiary) dentin.
The case study illustrates the use of Biodentine for direct pulp capping.
Four years ago a male patient, then 18, came for a routine check-up. Bitewing films recorded during the diagnostic assessment showed signs of an approximal carious lesion distally on tooth 15 (fig 1). The patient was informed about the need of having the carious lesion treated, but failed to show up at the scheduled appointment. At age 22 he came back complaining of discomfort of tooth 15 upon contact with cold food, drinks and air apparently caused by a buccal enamel fracture of tooth 15. On examination, a deep approximal carious lesion was found distally. The tooth was tested positive on CO2 snow sensitivity and negative on percussion. After thorough examination of the patient, an anaesthetic (Septanest, 1 ml; Septodont) was injected for terminal anesthesia and a rubber dam was put in place. Following cavity preparation the carious dentin was completely excavated. In the process the pulp cavity was exposed iatrogenically at two sites (fig 2). Clinically the pulp tissue was vital without any major bleeding, so that maintenance of tooth vitality by direct pulp capping was decided upon. Cavity with NaOCl (2.5 per cent) was done for hemostasis, clearing and disinfecting the cavity. Biodentine was chosen for direct pulp capping. Mixed as recommended by the manufacturer, Biodentine was applied to the exposed pulp tissue for direct capping and for temporary restoration so the entire cavity was filled with the bioactive cement (fig 4) after placing a matrix band (AutoMatrix; Dentsply-Caulk), (fig 3). About 12 minutes after mixing (after Biodentine had set) occlusion was checked (fig 5). At the follow-up visit four days after direct capping the patient reported some increased cold and warm sensitivity of tooth 15, but no other subjective symptoms.
Three months after direct capping he returned for having the Biodentine filling (fig 6) partially removed and topped by a composite filling to replace enamel. The symptoms he had originally reported had completely disappeared within a very short time. Tooth 15 was clinically normal and tested positive for sensitivity and negative for percussion. An anaesthetic (Septanest, 1 ml; Septodont) was injected for terminal anaesthesia and a rubber dam was placed. The Biodentine filling was reduced and kept as a base/dentin substitute (fig 7) and a matrix band as well as wedges (Composi-Tight 3D; Garrison) were applied (fig 8). Then the entire cavity was etched with phosphoric acid, a dentin adhesive (Optibond FL; Kerr) and a composite (Grandio; VOCO) was applied (figs 9 and 10). At the follow-up visit six months after direct capping, tooth 15 was clinically normal and again tested positive for sensitivity and negative for percussion. The dental film recorded at that time did not show any pathological findings apically (fig 11).
Biodentine was shown to be biocompatible (it does not damage pulpal cells in vitro or in vivo) and is capable of stimulating tertiary dentin formation. Hard tissue formation is seen after indirect and direct capping with Biodentine. Used for pulp capping, the material offers some benefits versus calcium hydroxide: It is stronger mechanically, less soluble and produces tighter seals. This qualifies it for avoiding three major drawbacks of calcium hydroxide, mechanical instability and the resultant failure of preventing microleakages.
Compared to other materials Biodentine handles easily and needs much less time for setting. Unlike other Portland cement-based products, it is sufficiently stable so that it can be used both for pulp protection and temporary fillings. This is why the manufacturer recommends to fill the entire cavity completely with Biodentine in a first step and to reduce it to a base/dentin substitute level in a second visit one week to six months later before definitive restoration. For successful capping it is, however, important to seal the cavity against bacterial invasion in a one-stage procedure. While there is extensive evidence documenting that composite fillings are leak-proof, little pertinent data is available for Biodentine. Another argument against the two-stage procedure recommended by the manufacturer is the uncertain cooperativeness of patients: will or will they not show up for a second visit? Add to all this that the inevitable repeated cavity preparation during the second visit exposes the pulp tissue, damaged as it already is by prior direct capping, to more stress. This can be avoided by a single-stage approach. Consequently, studies are underway to find out whether a single-stage procedure is feasible, such as applying Biodentine for pulp capping or pulp protection and placing a filling (a composite) for permanent restoration during one visit. When opting for this approach it is, however, important to wait for Biodentine to set (about 12 to 15 minutes after mixing) before proceeding with the restorative treatment. Definitive recommendations cannot be made before the results of ongoing studies are available.
Of note, Biodentine fillings were found to show marginal material loss at the follow-up visit after three months. This may be attributable to an incorrect handling. During occlusal adjustment, Biodentine should not be prepared with rotating instruments and should not come into contact with water. It should rather be applied into the cavity with cement pluggers using light pressure, and carving instruments should be used for occlusal adjustment. Subsequent polishing of the Biodentine filling should be omitted. Excessive pressure or exaggerated trimming and polishing may disrupt the crystalline structure of Biodentine with resultant loss of material strength.
It should be remembered that, aside from the choice of the right capping material (a material which is biocompatible and capable of stimulating the formation of hard tissue) other factors also play an important role for direct capping to be successful: the pulp tissue should be clear of bacteria or bacterial toxins. In clinical terms, this means the tooth should be asymptomatic and that pulp bleeding after exposure should be easily and rapidly controllable. Meticulous hemostasis is indispensable. Blood clots left at the material/pulp interface set the scene for treatment failure. Sodium hypochlorite is an ideal candidate for hemostasis, because it readily controls bleeding, while at the same time disinfecting the cavity. Microbial contamination of the pulp tissue during treatment should be meticulously avoided. This is best achieved with a rubber dam when treating on the dentin third close to the pulp, which reliably prevents the invasion of microorganisms from the oral cavity or saliva. Preventing microorganisms from entering the pulp is a key factor for successful direct capping. By contrast, patient age and the size or site of pulp exposure at best play a secondary role or are altogether irrelevant.
It goes without saying that a follow-up time of six months is much too short for evaluating the long-term success of a capping material. Problems associated with direct capping tend to occur up to five years post-treatment. In more than 50 per cent of the problem cases direct capping fails within the first two years. Teeth still vital five years after direct capping stand a good chance of retaining their vitality. More long-term clinical studies are, therefore, needed for a definitive evaluation of Biodentine.
Biodentine is an interesting and promising product, which has the potential to make major contributions to maintaining pulp vitality in patients judiciously selected for direct pulp capping.