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practice consists in applying agents directly or indirectly on pulp tissue. Although the goal of vital pulp therapy is the complete regeneration of tissues lost to decay or traumatic injuries (6), it is unlikely that the current therapies are capable of stimulating the formation of native den-tine (7). In this context, primary odonto-blasts and dental pulp stem cells con start tertiary dentine formation as reactionary and reparative dentinogenesis. Reactionary dentinogenesis occurs after moderate den-tine injury if primary odontoblasts are pres-ent to secrete dentine. However, in case of death of primary odontoblasts due to tissue damage, odontoblast-like cells can recruit stem/progenitor cells in a process of repar-ative dentinogenesis (8). Furthermore, the extracellular dentine matrix contains bioac-tive molecules that are sequestered within dentine during dentinogenesis, including growth factors, cytokines, and other matrix molecules, which are capable of stimulating

Calcium hydroxide and MTA in vital pulp therapy

Francesca Cerutti, Davide Guglielmi

The first goal of a restorative therapy is to preserve the vitality of the tooth, neverthe-less in everyday practice clinicians often face the problem of treating teeth whose pulp has been exposed without clear directions from the Literature, since there has been no agreement on the best way to treat vital permanent teeth with cariously exposed pulp (1). On one hand, pulpectomy is the most suit-able treatment for preventing and/or healing apical periodontitis (2) and gives reliable out-comes (3). On the other hand, the progno-sis in term of survival rate of endodontically treated teeth is not as good as vital teeth, especially in molars (hazard ratio, 7:1 (4) due to the loss of proprioceptive function, damping property and tooth sensitivity (5).Several treatments aimed at protecting the vitality of the dental pulp exposed as a result of large decays, accidental trauma or prepa-ration techniques have been studied(6) under the name of vital pulp therapy: this

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dentine secretory activity via odontoblasts or odontoblast-like cells (6).The procedures classified as vital pulp ther-apies (or dentin-pulp complex regenerative procedures) are the direct pulp capping, indirect pulp capping and pulpotomy. Direct pulp capping is defined as covering an exposed dental pulp with a protective agent, indirect pulp capping is referred to the application of a protective agent on a thin layer of dentin over the nearly exposed dental pulp, while pulpotomy is the surgi-cal removal of inflamed coronal part of the dental pulp in the exposed pulpal tissue to save the remaining healthy tissue. In these procedures, clinicians attempt to provide an effective pulp capping with appropriate sealing ability, maintain the vitality of pulp tissues and promote the formation of a den-tinal bridge and other tissues including neu-ral cells (5, 9). These procedures offer good alternatives to root canal therapy for teeth with immature or mature apices when pulp is exposed with reversible injury and with-out signs of inflammation, offering a more conservative approach.Several studies published in the Literature showed that the efficacy of direct and indi-rect pulp capping might be affected by the biomaterials used and their biological properties because most of dental materials release inorganic trace elements, and most of inorganic trace elements regulate angio-genesis (9, 10).In addition to regeneration of dental pulp tissue, apexogenesis and apexification are other endodontic procedures that are performed in immature permanent teeth. Apexogenesis is the procedure that enables the immature permanent teeth to continue root end development, while the apexifica-tion provides a calcified barrier at the end of immature root by biocompatible material next to periapical tissue. It has been reported that the revascularization process occurs through the angiogenesis events derived from the periapical tissues that grow into the engineered pulp tissue. The immature teeth with open apices are the best candi-dates for these regenerative procedures (9).Due to the interactions between dental materials and cells, the research has investi-gated which material gives the best results in terms of biocompatibility and pulp inflam-mation : the goal of treating the exposed pulp with an appropriate pulp capping

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Fig.1 Pre-operative pictureFig. 2 Decay removal leads to a large cavity, where the pulp is protected from a thin layer of dentineFig. 3 Indirect pulp capping is performed with Ca(OH)2 (Opacal, Produits Dentaires SA, Switzerland) Fig. 4 Composite restorations are performed Fig. 5 While removing a large carious lesion, there was an accidental exposure of the pulp on the mesio-buccal aspect of tooth 3.7Fig. 6 Direct pulp capping with Ca(OH)2 (Opacal, Produits Dentaires SA)Fig. 7 Direct composite restorationFig. 8 Pre-operative x-ray of tooth 4-7Fig. 9 Single tooth anesthesiaFig. 10 Isolation with rubber damFig. 11 The cavity during the decay removal

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material is to promote the dentinogenic potential of the pulpal cells. Historically many different materials have been used for these procedures, including resin-modified glass ionomer cements, tricalcium phosphates,

Fig. 12 The cavity after the removal of the demineralized tissue : there are two small com-munications between the pulp chamber and the cavityFig. 13 MAP system (Produits Dentaires SA, Switzerland) is used to carry PDTM MTA White (Produits Dentaires SA, Switzerland) to execute the pulp cappingFig. 14 PDTM MTA White is positioned inside the cavityFig. 15 A microbrush is used to gently adapt the product to the communicationFig. 16A second increment of PDTM MTA White (Produits Dentaires SA, Switzerland) is applied to the second communicationFig. 17 The excesses are gently removed with a dental excavatorFig. 18 A probe is used to assess the hardening of the materialFig. 19 The restorative process starts with selective etching of enamel first, then dentineFig. 20 A resin primer is applied on the dentineFig. 21 The bonding agent is appliedFig. 22 The composite restoration

hydrophilic resins, and calcium hydroxide.The success of different pulp capping mate-rials has been measured by thickness of the dentinal bridge, morphology of the dentinal bridge, intensity of pulpal inflammation, presence of odontoblasts cells and biocom-patibility (11).Calcium hydroxide has been considered the gold standard for pulp capping for decades due to its alkalinity, that provides it with antibacterial activity and stimulates dentin formation (Fig. 1-7). It also increases the recruitment, migration, proliferation, and mineralization of DPSCs and periodon-

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Fig. 23 1 year recallFig. 24 Initial situation : a large decay in a tooth with open apicesFig. 25 The phases of decay removal and extirpation of the pulp present in the chamberFig. 26 MTA is positioned into the cavity in order to preserve tooth vitality and promote the apexificationFig. 27 In a second appointment a direct restoration is performedFig. 28 Final clinica and radiographic appearance

tal ligament stem cells (PDLSCs) through the expression of STRO-1 and CD146 mark-ers. Moreover, Ca(OH)

2 has pro-angiogenic

effects attributed to the release of growth factors preserved in the dentin matrix includ-ing TGF-β, platelet-derived growth factor (PDGF), fibroblast growth factor (FGF) and insulin-like growth factor (IGF) (9). Schröder indicated that Ca(OH)

2 can induce a lim-

ited necrotic zone on the surface of pulp tissue at the application sites (12). However, the pulp capping procedure can fail due to the porosity of the dentinal bridge that is produced, the poor adhesion between calcium hydroxide and dentin, and calcium hydroxide inability to provide a long-term seal against microleakage (13). Some studies have suggested that the effect of using of calcium hydroxide or glass ionomer cement on dentine caries is not superior to the use of an inert material (such as wax) (14), in indi-rect pulp capping of primary (15) or perma-nent teeth (6).Mineral trioxide aggregate (MTA) can also be used as a pulp capping material because it leads to significantly greater frequency of dentin bridge formation, thicker and less porous dentin, and less pulp inflammation compared with calcium hydroxide. Recent research has shown that MTA, when placed in direct contact with the human dental pulp cells, differentiated them into odonto-blast-like cells and creates no layer of necrosis in the pulp. At the cellular level, MTA has also been shown to induce the recruitment and proliferation of undifferentiated cells to form a dentinal bridge, while reducing inflamma-tion compared with calcium hydroxide.Ferreira et al. evaluated the effect of pulpo-tomy agents including Ca(OH)

2, MTA, adhe-

sive resin, and formocresol on dental pulp tissue fibroblasts and reported that MTA was the only pulpotomy material which increased the release of IL-1β and IL-8 by fibroblasts (16).For direct pulp capping an overall success rate of 80,5 % for MTA has been reported when compared with calcium hydroxide (59 % of success rate) up to 123 months (17). The cons of using MTA consist in long setting times of the material and the potential dis-coloration of the crown of the tooth due to its content in metal oxides. A recently intro-duced material, PDTM MTA White (Produits Dentaires SA, Switzerland) overcomes these two problems thanks to its bismuth-free

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composition and to its fast setting time. (Fig. 8-23) A recent systematic review of the Literature concluded that direct comparison of the success rate of using either calcium hydrox-ide or MTA as pulpal medicament showed no statistically significant difference. Evi-dence shows that both calcium hydrox-ide and MTA provide satisfactory outcome when used as pulpal medicament in vital pulp therapy. It is inconclusive about which of the 2 materials performs better (5).One of the most important aspect to con-sider when doing vital pulp therapy is the selection of the case: the difficulty in assess-ing whether the status of the pulp is revers-ible or irreversible makes the decision mak-ing process harder. Basing on the age of the patient is not a universally accepted method : it has been recommended that vital pulp treatment should be performed only in young patients because of the high healing capacity of pulp tissue in young patients in comparison with old patients (Fig. 24-32) (13). However, the data from the Literature are not sufficient to show the effect of the age of the patients on the clinical outcome : patients with age ranging from 6–70 years were treated suc-cessfully with vital pulp therapy, stressing the healing potential of pulp tissue after the removal of the cause of the disease (5).

of the toothFig. 29 X-ray follow up from 0 to 12 monthsFig. 30 18 months follow upFig. 31 24 months follow upFig. 32 30 months follow up

1. Ward J. Vital pulp therapy in cariously exposed permanent teeth and its limitations. Australian endodontic journal : the journal of the Australian Society of Endodontology Inc. 2002 ; 28:29–37.

2. Gesi A, Hakeberg M, Warfvinge J, Bergenholtz G. Incidence of periapical lesions and clinical symptoms after pul-pectomy : A clinica and radiographic evaluation of 1-versus 2-session treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006 ; 101 : 379-88.

3. Friedman S. Expected Outcomes in the Pre-vention and Treatment of Apical Periodontitis. In: Orstavik D, Pitt Ford TR, editors. Es-sential Endodontology. 2nd ed. Oxford, UK: Blackwell Munksgaard Ltd ; 2008. p. 408-71.

4. Caplan DJ, Cai J, Yin G, White BA. Root canal filled versus non-root canal filled teeth:A retrospective comparison of survival times. J Public Health Dent. 2005 ; 65:90-6.

5. Aguilar P, Linsuwanont P. Vital pulp therapy in vital permanent teeth with cariously exposed pulp: a systematic review. Journal of endodontics. 2011 ; 37 (5) : 581-7.

6. da Rosa WLO, Piva E, da Silva AF. Disclosing the physiology of pulp tissue for vital pulp therapy. International endodontic journal. 2018 ; 51(8) : 829-46.

7. Smith AJ, Duncan HF, Diogenes A, Simon S, Cooper PR. Exploiting the Bioactive Proper-ties of the Dentin-Pulp Complex in Regenera-tive Endodontics. J Endod. 2016;42(1) : 47-56.

8. Smith JG, Smith AJ, Shelton RM, Cooper PR. Antibacterial acti-vity of dentine and pulp extracellular matrix extracts. Int Endod J. 2012;45(8):749-55.

9. Saghiri MA, Asatou-rian A, Garcia-Godoy F, Sheibani N. Effect of biomaterials on angiogenesis during vital pulp therapy. Dental materials journal. 2016;35(5) : 701-9.

10. da Rosa WLO, Lima VP, Moraes RR, Piva E, da Silva AF. Is a calcium hydroxide liner necessary in the treatment of deep caries lesions? A systematic review and meta-analy-sis. Int Endod J. 2018.

11. Holland R, Filho JA, de Souza V, Nery MJ, Bernabé PF, Junior ED. Mineral trioxide aggregate repair of late-ral root perforations. J Endod. 2001;27(4) : 281-4.

BIBLIOGRAPHY

12. Schröder U. Effects of calcium hydroxide-containing pulp capping agents on pulp cell migration, proliferation, and differentiation. Journal of dental research. 1985;64:541-8.

13. Cohenca N, Paranjpe A, Berg J. Vital pulp therapy. Dental clinics of North America. 2013;57(1):59-73.

14. Corralo DJ, Maltz M. Clinical and ultrastructural effects of different liners/restorative materials on deep carious dentin: A randomized clinical trial. Caries Research. 2013;47:243-50.

15. Schwendicke F, Brouwer F, Stolpe M. Calcium Hydroxide versus Mineral Trioxide Aggregate for Direct Pulp Capping: A Cost-effectiveness Analysis. J Endod. 2015;41(12):1969-74.

16. Ferreira NS, Martinho FC, Cardoso FG, Nascimento GG, Carvalho CA, Valera MC. Microbiological profile resistant to different intracanal medications in primary endodontic infections. J Endod. 2015;41(6):824-30.

17. Mente J, Hufnagel S, Leo M, Michel A, Gehrig H, Panagidis D, et al. Treatment outcome of mineral trioxide aggregate or calcium hydroxide direct pulp capping: long-term results. J Endod. 2014;40(11) : 1746-51.

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