in immature teeth radiographically, as well as absence apical periodontitis [219]. A successful outcome in mature permanent teeth with symptoms no worse than reversible pulpitis indicates that a pulp‐capping procedure using an HCSC will be successful in approximately 80–90% of cases [63, 68, 82]. However, success is likely to be affected by the location (interproximal, occlusal) [79] and depth [66] of the carries, as well as operator skill [52, 63, 69] and material used [66, 68]. Other factors have not been consistently shown to be critical in determining outcome; these include patient age [83, 85, 196] and size of exposure [53, 118]. Interestingly, recent evidence highlights the potential of full pulpotomy to be as effective as pulpectomy in teeth with signs and symptoms suggestive of irreversible pulpitis [11, 84,220–222]. That said, there is a lack of prospective controlled trials using standardized materials, irrigants, caries depth symptoms, and so on in this area; this will need to be addressed moving forward. Damaged immature teeth treated aseptically by VPT that remain vital will display continued root growth through the physiological processes of primary and ongoing secondary dentinogenesis.
2.5.2 Discolouration
Crown discolouration as a result of VPT does not constitute a biological failure of the procedure [219]; however, from the patient’s perspective, it may be of genuine concern. Initially, commercial MTA was available as ProRoot in a grey formulation, which was later superseded by a white product, marketed as being superior in aesthetic areas. For many endodontic applications such as apexification and perforation repair, the discolouration risk of MTA is not critical; however, this is not the case for applications in which the cement in placed in contact with pulp cells in the coronal aspect of the tooth (Figure 2.9). Notably, white ProRoot MTA has also been demonstrated to discolour teeth [135] – a process accentuated in the presence of irrigants such as sodium hypochlorite [223] and fluids like blood [224]. This discolouration has been attributed to the radiopacifier bismuth oxide, which forms a precipitate in the presence of collagen and sodium hypochlorite creating stains [225]. Other hydraulic calcium silicate materials contain other radiopacifiers, including zirconium oxide, which has been linked to a reduced colour change in Biodentine‐treated teeth [226–228]. Tooth discolouration is possible with all HCSCs, particularly in the presence of blood products, but next‐generation materials induce significantly less staining than ProRoot MTA [229], perhaps due to the removal of bismuth oxide. However, radiopacity is often reduced as a result. Interestingly, Biodentine’s radiopacity is consistently reported as being below ISO standards [230, 231], and indeed operators cannot clearly visualize it as distinct to dentine.
Figure 2.9 Discoloured maxillary left lateral incisor one year after a partial pulpotomy procedure using a hydraulic calcium silicate material containing bismuth oxide.
Source: Henry F. Duncan.
2.5.3 Setting Time and Handling
ProRoot MTA is limited clinically by a prolonged setting time [232, 233], which lasts several hours. As a result, the manufacturer claims the material should be applied over two visits – a feature which is not ideal for vital pulp applications. Newer HCSCs, including MTA Angelus, Biodentine, and resin‐modified calcium silicates such as TheraCal LC, advertise significantly shorter or instant setting times, facilitating completion of treatment in one visit. Notably, the setting time of Biodentine is not always predictable, with it often taking significantly longer than the advertised time even for initial setting to occur [145, 230]; however, it is still much quicker than ProRoot MTA. It has been reported that MTA Angelus and Biodentine have similar setting times [234]. Light‐cured HCSCs, whilst offering an instantly setting material, have been shown to be cytotoxic and are not recommended for use as direct pulp‐capping materials [187]. Traditionally, MTA has been reported to be difficult to handle because of its consistency and formulation [232, 235], whilst Biodentine is considered easier to mix and use [234]. A recent questionnaire‐based study investigated Biodentine and MTA in VPT and highlighted that many dentists avoided using any calcium silicate materials, citing reasons of cost, lack of training, and difficulties in material handling [236].
2.6 Conclusion
Preserving the health of the dental pulp is an important aspect of modern endodontics. If successful, pulp preservation is a minimally invasive, biologically based, and technically undemanding alternative to pulpectomy. Therefore, selective caries removal, stepwise excavation, pulp capping, and pulpotomy are an essential part of the treatment armamentarium of every dentist. The advent of HCSCs has provided renewed impetus in VPT, and they are the current material of choice in this area. Although the exact mechanisms remain to be elucidated, pulp‐capping materials like calcium hydroxide and MTA appear to stimulate the release of biologically active molecules from pulp cells and the dECM, stimulating dentinogenesis. Although the future of this area may involve molecular diagnostic biomarker assays and targeted third‐generation biomaterials, prospective randomized trials using modern materials are required to support promising preliminary clinical data in the meantime.
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