RestorativeandAestheticDentistry
Stéphanie Mouawad Simon Artine, Pétra Hajjar, Robert McConnell, Jean-Claude Fahd and Joseph Sabbagh
Frequently Asked Questions in Direct Pulp Capping of Permanent Teeth Abstract: Direct pulp capping is a proven method of preserving tooth vitality of a mature permanent tooth in cases of pulp exposures. The indications for this treatment, treatment modalities and materials are discussed in this paper. Clinical Relevance: This paper answers many of the frequently asked questions by general practitioners, dental students and specialists about direct pulp capping. Dent Update 2014; 41: 298–304
Dentists in their daily practice use many restorative techniques. Among those, vital pulp therapies have always carried many question marks, resulting in some contradictions regarding the use and the success of this technique. Direct pulp capping of a pulp exposure can provide an opportunity for preserving pulpal tissue. This may result in the formation of tertiary dentine, thereby preserving the vitality of the tooth and avoiding the need for root
Stéphanie Mouawad, Resident, Simon Artine, Resident, Pétra Hajjar, Resident, Restorative and Aesthetic Dentistry Department, School of Dentistry, Lebanese University, Beirut, Lebanon, Robert McConnell, Professor, Centre for Dentistry, Queen’s University Belfast, UK, Jean-Claude Fahd, Chairperson and Joseph Sabbagh, Assistant Professor, Restorative and Aesthetic Dentistry Department, School of Dentistry, Lebanese University, Beirut, Lebanon.
298 DentalUpdate
canal therapy. When direct pulp capping is carried out, the patient must be fully informed and advised that, if symptoms occur, they must return for re-assessment of pulp vitality.1 An understanding of the properties of available materials will help in the decision-making to obtain long-lasting functional restorations on vital teeth. This article answers some of the questions involving direct pulp capping as a treatment option for pulp exposures, the different materials and techniques used in this procedure and the success rate of direct pulp capping using a question and answer format. However, it is up to the reader to decide whether to perform direct pulp capping or not by carefully selecting the suitable cases for this treatment.
Direct pulp capping
dentine. It aims to maintain the pulp vitality and its normal responsiveness to electrical and thermal tests.2 On the other hand, an indirect pulp capping can also be performed when excavation of the pulpal caries can be stopped at stained but firm dentine, known as affected dentine. Calcium hydroxide lining is placed over the pulpal dentine prior to the placement of a definitive restoration.3 Q2. When is direct pulp capping indicated?
A. When a small (1 mm2), or involves contamination of any kind, it is better not to undertake pulp capping. It may also be contra-indicated to perform this treatment in case of systemic diseases (diabetes, cancer or blood disorders).1,4 Q4. Is direct pulp capping a suitable treatment for primary teeth?
A. In general, direct pulp capping treatment is recommended for permanent teeth and not primary teeth because of the poor prognosis.5,6 The high failure rate of direct pulp capping in primary teeth is explained by undifferentiated mesenchymal cells in the primary pulp which may become odontoclasts, leading to internal resorption.5 This increase in resorption in primary teeth is also due to physiological root resorption that is already in progress and an increased blood supply is stimulated. The root resorption may not be visible radiographically in terms of root blunting.7 Q5.What is the most suitable restoration to place over a pulp-capped tooth?
A. After pulp capping, a hermetic seal against bacterial infiltration is essential to guarantee the success of the treatment. According to a retrospective study by Barthel et al, the placement of a definitive restoration within the first two days after pulp exposure contributed significantly to increase the survival rate of these teeth.8 Currently, the restoration of choice to cover the pulp-capping material is a RMGIC (Resin Modified Glass Ionomer Cement) prior to etching and bonding the enamel and dentine surfaces for a composite resin restoration. Glass ionomers provide resistance to acid etch, condensation pressure and dissolution.9 Q6. What materials are used for pulp capping?
There are four products commonly used for direct pulp capping; May 2014
frequently used products and their composition are summarized in Table 1. Calcium hydroxide (Ca(OH)2) is the most common direct pulp agent. For pulp capping it is used as a two-paste product. It has excellent antibacterial and disinfectant properties but a number of disadvantages, including its solubility in water and the fact that it does not seal the exposed pulp from the external environment and has poor mechanical properties. For these reasons, a protective base material, such as a RMGIC, is required to provide an adequate seal of the pulp.9 Mineral trioxide aggregate (MTA), developed at the University of Loma Linda (USA), to seal communications between the root canal system and the external tooth surface,10 has been recommended for direct pulp capping.11 It has fine hydrophilic particles mixed with sterile water, which results in a colloidal gel (pH of 12.5). This gel solidifies to a hard structure within approximately 4 hours with low or no solubility.12 MTA is antibacterial and biocompatible and has no mutagenic potential. Unlike calcium hydroxide it creates an excellent seal2 and does not need any additional protection. Two commercial forms of MTA are available on the dental market; ProRoot® MTA (grey and white, Maillfer, Dentsply, Switzerland) and MTA-Angelus (Angelus Soluções Odontológicas, Londrina, Brazil) introduced in 2001.13 The two commercial brands of MTA have similar chemical composition, although ProRoot® MTA presents a slightly higher percentage of bismuth oxide than MTA-Angelus.14 Also, the particles of the MTA-Angelus have relatively low circularity and wide size distribution and are less homogeneous than ProRoot® MTA.15 No statistically significant difference was found between the two brands of MTA when cytotoxic effects on human endothelial cells were tested.12 Tri-calcium phosphate is another pulp-capping agent mainly indicated in bone regeneration procedures as it promotes osteoblastic formation of hard tissue. Alpha-tricalcium phosphate (α-TCP), a powder of apatite ceramics, is mixed with a saline or low acid solution and converted into hydroxyapatite or octacalcium phosphate. It sets and hardens at room temperature. Studies have shown that dentinal bridge formation occurs by direct
apposition on the pulpal wall. The bridge is contiguous to the pulp, thick and has minimal pulpal inflammation effect with no necrotic layer. The odontoblasts were present directly under, and in contact with, the bridge.16,17 However, the hard tissue barrier formation was reported to be slower than that with Ca(OH)2.17 Bio-Aggregate® (Innovative Bioceramix Inc IBC, Canada) is a root canal repair material composed of Bio-ceramic nano-particles. It is indicated in the repair of root perforations and root resorption, in apexification procedures and as a direct pulp-capping agent. It presents as pure white powder and liquid mixed together to form a thick paste-like mixture. MTA and Bioaggregate have similar chemical composition with some differences; Bioaggregates contain tantalum oxide instead of bismuth oxide in the MTA.18 Recently, Septodont launched Biodentine™, an Active Biosilicate Technology™ and a calcium silicate-based cement (Ca3SiO5-based cement) developed as a dentine substitute. Besides the usual endodontic indications of this class of calcium-silicate cements (repair of perforations, or resorption, apexification, and retrograde root-end filling), Biodentine™ is indicated in the restoration of deep or large crown carious lesions as it provides a very tight seal, without post-operative sensitivity, and ensures the longevity of restorations in vital teeth. Biodentine™ is mixed in any triturator with a minimum speed of 4,000 rpm (Figure 1). Figure 2 shows a pulp-capping case using BiodentineTM. After 6 weeks, the vitality of the pulp is checked and part of the BiodentineTM is partially removed and a ClI cavity is prepared using a pear-shaped diamond bur. The cavity is then restored conventionally using an adhesive system and resin-based composite. Q7. What is the physiological process of dentine bridge formation?
A. When applied over an exposed pulp, the pulp-capping agent causes a series of inflammatory responses leading to the formation of a hard-calcified dentine bridge. Owing to a high pH (12.5), calcium hydroxide causes liquefaction necrosis of the superficial pulp removing up to 1.5 mm of the inflamed tissue. This is followed by the neutralization of toxicity in DentalUpdate 299
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RestorativeandAestheticDentistry
Generic Material Commercial Products
Manufacturer
Composition
Presentation
Ca(OH)2 Dycal® Dentsply- Caulk, USA
1,3-Butylene glycol disalicylate Zinc oxide Zinc oxide Calcium phosphate Calcium tungstate Iron oxide pigments
Base (Paste)
Life® Kerr, CA, USA
Calcium hydroxide N-ethyl-o/p-toluene sulfonamide Zinc oxide Titanium dioxide Zinc stearate Iron oxide pigments (dentine shade)
Catalyst (Paste)
Calcium hydroxide Zinc oxide Butyl benzene sulfonamide
Base (Paste)
Barium sulphate Titanium dioxide Methyl salicylate
Catalyst (Paste)
MTA ProRoot®MTA Dentsply, USA Tricalcium silicate Powder Tricalcium aluminate Tricalcium oxide Silicate oxide H2O MTA-Angelus® Angelus, Londrina, Calcium compounds Powder Brazil Distilled water Biosilicate Biodentine™ Septodont, USA
Tri-calcium silicate (C3S) Main core material Di-calcium silicate (C2S) Second core material Calcium carbonate and oxide filler Iron oxide shade Zirconium oxide Radiopacifier
Powder in capsules
Calcium chloride accelerator Hydrosoluble polymer water reducing agent
Liquid in single-dose pipettes
Bioaggregate Bio-Aggregate® Innovative Calcium silicate hydrate Powder BioCeramics (IBC), Calcium hydroxide Canada Hydroxyapatite Tantalum oxide Amorphous silicon oxide Deionized water Liquid Table 1. Direct pulp-capping products available on the market and their compositions.
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RestorativeandAestheticDentistry
a
b
of the cavity first, moving circumferentially, removing the deepest remaining caries closest to the pulp last. In this way, an inadvertent exposure would be in a clean caries-free field. The exposure should be cleansed with 3% sodium hypochlorite. This will act as a bactericidal agent without causing an adverse pulpal reaction. Control of pulpal haemorrhage can be achieved with light pressure using a dry cotton pellet. Alternatively, the cotton pellet may be moistened with sodium hypochlorite, saline or local anaesthetic without epinephrine, ferric sulphate or slurry of calcium hydroxide.20,21 Q9. Is the placement of rubber dam mandatory during pulp capping?
c
A. Rubber dam will reduce bacterial contamination of an exposed pulpal site and provide an appropriate environment for successful resin bonding, creating a good seal. Q10. Is pulp capping influenced by a patient’s age and gender?
Figure 1. (a) Biodentine™ pack containing powder and liquid. (b) Adding water to Biodentine™ powder. (c) Mixed Biodentine™.
the deep layers with coagulative necrosis, which irritates the adjacent pulp and causes a minor inflammation leading to the formation of the dentine bridge. (This causes stimulation of the pleuripotential pulpal cells, which differentiate into odontoblasts, and these in turn lay down a calcified dentine bridge). Investigators have reported that MTA induces pulpal cell proliferation, cytokine release, hard tissue formation and the synthesis of an interface with dentine similar to hydroxyapatite composition.19 Q8. What is the best technique for cavity disinfection and haemorrhage control prior to pulp capping?
A. It is important to avoid bacterial contamination of the pulp exposure in order to allow and promote healing. Caries should be removed at the periphery
302 DentalUpdate
A. A patient’s age has an influence on the success or failure rate of pulp capping. Bogen et al found, in an observational study, that pulpal repair and pulp-capping success appears to be more favourable in young patients.19 This success may be attributed to the presence of larger apical foramina and greater vascularization of the pulp. An increased blood flow allows for better immune cell surveillance and response.19 On the other hand, the success of pulp capping is not dependent on patient gender.22 Q11. Are resin adhesive systems indicated for pulp capping?
A. The sealing potential of resin adhesive systems makes them an attractive alternative for direct pulp capping, preventing bacteria from entering the pulp. However, Stanley and Pameijer found that the application of acid to exposed pulps caused haemorrhage that was difficult to control.23 It is difficult to achieve an effective resin seal under such conditions, and consequently poor results were obtained. Modena et al also agree that adhesives result in lower pulp healing and induce chronic inflammation, even in the absence of bacteria. Inflammation is a poor environment
for pulp healing; a pulp inflamed due to caries will have decreased healing capacity.24 According to Cui et al, selfetching adhesives are relatively toxic to pulp tissue. This may be due in part to poor marginal sealing at the tissue-material interface.25 Another issue when placing adhesives directly on the pulp is the heat generated by the light-curing devices. It has been shown that an intrapulpal temperature increase of more than 11°C can lead to irreversible pulp damage.26 It can be concluded that resin adhesives are therefore not suitable as a direct pulp-capping agent. Q12. How long do you need to wait to be sure of direct pulp-capping success?
The literature is divided on when to measure the successful outcome of direct pulp capping. Some publications demonstrated that the survival rate of directly capped pulp tissue, using calcium hydroxide, decreases over time when compared to shortterm evaluations and the most unfavourable treatment outcomes occur within the first year after the treatment. According to the European Society of Endodontology, direct pulp capping should be assessed no longer than six months post-operatively and then at five yearly intervals.29 Matsuo et al suggested that the necessary interval for an adequate post-operative follow-up examination is 21 months.30 It is obvious that long-term outcomes (10 years) are the most relevant for the patients but, for convenience, in most of the clinical studies, the evaluation period is shorter. Success rates of direct pulp capping in a carious field have varied, depending on the technique and materials.8,22,27,28,29,30 In humans, success rates ranged between 13% and 98% in 1–10 year retrospective studies using calcium hydroxide (Table 2). Q13. What are the tests for controlling and monitoring a pulp-capped tooth?
A. Follow-up of pulp-capped teeth includes clinical and radiographical examinations. During recall appointments, patients’ self-reports concerning pain and sensitivity are recorded and pulp-capped teeth are tested with a cold stimulus. Radiographs are taken to evaluate reparative dentine formation, pulpal calcification, continued normal root development and May 2014
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RestorativeandAestheticDentistry
Authors
Sample Size
Time Elapsed
Success Rate
Armstrong and Hoffman(1962)27
46
2–16 months
97.8%
Heyduck and Wagner (1978)
210
1-5 years
61.4%
Haskell et al (1978)29
149
5 years
87.2%
Matsuo et al (1996)30
44
Group with follow-ups for 3–18 months
80–83%
Group with follow-ups for 21 months
91.7%
Group with follow-ups for 24 months
100%
Barthel et al (2000)8
5 years
37%
10 years
13%
Al-Hiyasat et al (2006)
5 years
59.3%
28
123
22
204
Table 2. Evaluation of the success rate of pulp-capping techniques.
a
e physiological development and formation of a root end.32 Other authors have reported a high level of success using partial pulpotomies in caries exposures.33,34
b
c
d
Figure 2. (a) Deep caries resulting in direct pulp exposure. (b) BiodentineTM applied over the exposed pulp and in all the cavity (its setting time is 10 min); (c) 6 weeks later; (d) part of the BiodentineTM is removed. (e) Final composite restoration.
the absence of pathosis, such as internal root resorption and apical periodontitis.31 The marginal integrity of the final restorations should always be evaluated.19 Clinical signs indicative of a favourable outcome are a normal response to pulp sensitivity tests, absence of pain or tenderness to percussion and absence of swelling, sinus tract and pathological mobility. Also, in anterior teeth, absence of tooth discoloration is the most important factor to be considered.31,7 Q14. Can you carry out a partial pulpotomy on permanent teeth?
Partial pulpotomy is the removal of a small portion of the vital coronal pulp and preserving the vitality of the remaining coronal and radicular pulp tissue. This technique is preferred in order to encourage May 2014
Q15. What are the future trends and perspectives for direct pulp capping?
A. Novel techniques are being developed to regenerate rather than to restore lost hard dental tissue, including enamel, dentine and pulp tissue. The regeneration of dentine is considered feasible as it is in direct contact with a highly vascularized and innervated pulpal tissue. Odontoblastic cells in the pulp continue to produce secondary dentine, even after tooth eruption at low level, and they secrete tertiary dentine as a repair reaction with the help of progenitor cells that will be, at this point, triggered to differentiate into odontoblastic-like cells under the influence of specific growth factors. Research on pulpal tissue regeneration is based on growth factor delivery, stem cell delivery and geneenhanced tissue regeneration. With growth factor delivery, TGF-beta 1 (polypeptide responsible for the control of cell growth, cell proliferation, cell differentiation and apoptosis) is implanted intra-pulpally to induce odontoblastic-like cell differentiation and reparative dentine formation; nevertheless its action is limited. Other growth factors, such as insulin-like growth factor in mechanically exposed DentalUpdate 303
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RestorativeandAestheticDentistry
pulps, have been reported. This will reduce inflammation, preserve tooth vitality and promote pulp repair.35 Future trends on pulp capping also include the use of lasers, more specifically CO2 Laser, which was found to have anti-inflammatory, cell biostimulation and decontamination effects on pulpal cells and dentine.36 CO2 Laser used in direct pulp capping was found to increase the percentage of pulp vitality preservation and the thickness of the dentinal bridge newly formed after pulp exposure significantly.36
7.
8.
9.
10.
Summary
11.
Preservation of the vitality of a tooth is the aim of the restorative clinician. However, the clinician is often faced with a direct pulp exposure as a result of the operative procedure or trauma. Criteria for success are outlined in this paper using an easy reference design.
12.
13.
Conclusion Direct pulp capping, although a very technique and case selection sensitive procedure, is considered to be a basic conservative approach and, when it is found to be indicated, should be performed. The high success rate found after a long-term evaluation, and the variety of products that ensure such a rate, are plus factors when considering direct pulp capping.
References 1. 2.
3.
4. 5.
6.
Swift EJ, Trope M, Ritter AV. Vital pulp therapy for the mature tooth – can it work? End Top 2003; 5: 49–56. Mussolino De Queiroz A, Assed S, Leonardo MR, Nelson-Filho P, Bezerra Da Silva LA. MTA and calcium hydroxide for pulp capping. J Appl Oral Sci 2005; 13(2): 126–130. Murray PE, Windsor LJ, Smyth TW, Hafez AA, Cox CF. Analysis of pulpal reactions to restorative procedures, materials, pulp capping, and future therapies. Crit Rev Oral Biol Med 2002; 13(6): 509–520. Stockton LW. Vital pulp capping: a worthwhile procedure. J Can Dent Assoc 1999; 65: 328–331. Fuks AB. Pulp therapy for the primary and young permanent dentitions. Dent Clin N Am 2000; 44: 571–596. Rodd HD, Waterhouse PJ, Fuks AB, Fayle SA, Moffat MA. Pulp therapy for primary molars. Int J Ped Dent 2006; 16(S1): 15–23.
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14.
15.
16.
17.
18.
19.
20.
Tuna D, Olmez A. Clinical long-term evaluation of MTA as a direct pulp capping material in primary teeth. Int End J 2008; 41: 273–278. Barthel CR, Rosenkranz B, Leuenberg A, Roulet JF. Pulp capping of carious exposures: treatment outcome after 5 and 10 years – a retrospective study. J End 2000; 26(9): 525–528. Hilton T, Summitt J. Pulpal consideration. In: Fundamentals of Operative Dentistry. Summitt J, Robbins W, Hilton T, Schwartz R, eds. Quintessence Int 2006: pp101–123. Torabinejad M, Watson TF, Pitt Ford TR. Sealing ability of a mineral trioxide aggregate when used as a root end filling material. J Endo 1993; 19: 591–595. Abedi HR, Torabinejad M, Pitt Ford TR, Bakland LK. The use of mineral trioxide aggregate cement (MTA) as a direct pulp capping agent. J Endo 1996; 22: 199. Iwamoto CE, Adachi E, Pameijer CH, Barnes D, Romberg EE, Jeffries S. Clinical and histological evaluation of white ProRoot® MTA in direct pulp capping. Am J Dent 2006; 19: 85–90. Camilleri J. The chemical composition of mineral trioxide aggregate. J Cons Dent 2008; 11: 141–143. Oliveira MG, Xavier CB, Demarco FF, Pinheiro ALB, Costa AT, Pozza DH. Comparative chemical study of MTA and Portland cements. Braz Dent J 2007; 18: 3–7. Komabayashi T, Spângberg LS. Comparative analysis of the particle size and shape of commercially available mineral trioxide aggregates and Portland cement: a study with a flow particle image analyzer. J Endo 2008; 34(1): 94–98. Chohayeb AA, Adrian JC, Salamat K. Pulpal response to tri-calcium phosphate as a capping agent. Oral Surg Oral Med Oral Pathol 1991; 71(3): 343–345. Yoshiha K, Yoshiha N, Iwaku M. Histological observations of hard tissue barrier formation in amputated dental pulp capped with α-tricalcium phosphate containing calcium hydroxide. Endo Dent Trauma 1994; 10(3): 113–120. Gala-Garcia A, Imaculada K, Teixeira R, Henrique F, Wykrota L, Sinisterra RD, Cortés ME. Bioceramic/ Poly (glycolic)-poly (lactic acid) composite induces mineralized barrier after direct capping of rat tooth pulp tissue. Braz Oral Res 2010; 24(1): 8–14. Bogen G, Kim JS, Bakland LK. Direct pulp capping with mineral trioxide aggregate an observational study. J Am Dent Assoc 2008; 139: 305–315. Kitasako Y, Inokoshi S, Tagami J. Effect of direct resin pulp capping techniques on short-term response of mechanically exposed pulps. J Dent 1999; 27: 257–263.
D
21. Hafez AA, Cox CF, Tarim B, Otsuki M, Akimoto N. An in vivo evaluation of hemorrhage control using sodium hypochlorite and direct capping with a one- or two-component adhesive system in exposed nonhuman primate pulps. Quintessence Int 2002; 33: 261–272. 22. Al-Hiyasat A, Barrieshi-Nusair KM, Al-Omari MA. The radiographic outcomes of direct pulp-capping procedures performed by dental students: a retrospective study. J Am Dent Assoc 2006; 137: 1699–1705. 23. Stanley HR, Pameijer CH. Dentistry’s friend: calcium hydroxide. Oper Dent 1997; 22: 1–3. 24. Modena KC da Silva, Casas- Apayco LC, Atta MT. Cytotoxicity and biocompatibility of direct and indirect pulp capping materials. J Appl Oral Sci 2009; 17(6): 544–554. 25. Cui C, Zhou X, Chen X, Fan M, Bian Z, Chen Z. The adverse effect of self-etching adhesive systems on dental pulp after direct pulp capping. Quintessence Int 2009; 40(6): 26–34. 26. Zach L, Cohen G. Pulp response to externally applied heat. Oral Surg Oral Med Oral Pathol 1965; 19: 515–530. 27. Armstrong WP, Hoffman S Pulp cap study. Oral Surg Oral Med Oral Pathol 1962; 15: 1505–1509. 28. Heyduck G, Wegner H. Stomatol DDR. 1978; 28(9): 614–619. German. 29. Haskell EW, Stanley HR, Chellemi J, Stringfellow H. Direct pulp capping treatment: a long-term followup. J Am Dent Assoc 1978; 97(4): 607–612. 30. Matsuo T, Nakanishi T, Shimizu H, Ebisu S. A clinical study of direct pulp capping applied to cariousexposed pulps. J Endo 1996; 22(10): 551–556. 31. European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. Int Endo J 2006; 39: 921–930. 32. Cvek M. A clinical report on partial pulpotomy and capping with calcium hydroxide in permanent incisors with complicated crown fracture. J Endod 1978; 4: 232–237. 33. Ward J. Vital pulp therapy in cariously exposed permanent teeth and its limitations. Aust Endod J 2002; 28: 29–37. 34. Aguilar P, Linsuwanont P. Vital pulp therapy in vital permanent teeth with cariously exposed pulp: a systematic review. J Endod 2011; 37: 581–587. 35. Edwards PC, Mason JM. Gene-enhanced tissue engineering for dental hard tissue regeneration: (2) dentin-pulp and periodontal regeneration. Head Face Med 2006; 2: 16. 36. Nammour S, Tielemans M, Heysselaer D, Pilipili Ch, De Moor R, Nyssen-Behets C. Comparative study on dogs between CO2 laser and conventional technique in direct pulp capping. Rev Belge Med Dent 2009; 64(2): 81–86.
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Stéphanie Mouawad Simon Artine, Pétra Hajjar, Robert McConnell, Jean-Claude Fahd and Joseph Sabbagh
Frequently Asked Questions in Direct Pulp Capping of Permanent Teeth Abstract: Direct pulp capping is a proven method of preserving tooth vitality of a mature permanent tooth in cases of pulp exposures. The indications for this treatment, treatment modalities and materials are discussed in this paper. Clinical Relevance: This paper answers many of the frequently asked questions by general practitioners, dental students and specialists about direct pulp capping. Dent Update 2014; 41: 298–304
Dentists in their daily practice use many restorative techniques. Among those, vital pulp therapies have always carried many question marks, resulting in some contradictions regarding the use and the success of this technique. Direct pulp capping of a pulp exposure can provide an opportunity for preserving pulpal tissue. This may result in the formation of tertiary dentine, thereby preserving the vitality of the tooth and avoiding the need for root
Stéphanie Mouawad, Resident, Simon Artine, Resident, Pétra Hajjar, Resident, Restorative and Aesthetic Dentistry Department, School of Dentistry, Lebanese University, Beirut, Lebanon, Robert McConnell, Professor, Centre for Dentistry, Queen’s University Belfast, UK, Jean-Claude Fahd, Chairperson and Joseph Sabbagh, Assistant Professor, Restorative and Aesthetic Dentistry Department, School of Dentistry, Lebanese University, Beirut, Lebanon.
298 DentalUpdate
canal therapy. When direct pulp capping is carried out, the patient must be fully informed and advised that, if symptoms occur, they must return for re-assessment of pulp vitality.1 An understanding of the properties of available materials will help in the decision-making to obtain long-lasting functional restorations on vital teeth. This article answers some of the questions involving direct pulp capping as a treatment option for pulp exposures, the different materials and techniques used in this procedure and the success rate of direct pulp capping using a question and answer format. However, it is up to the reader to decide whether to perform direct pulp capping or not by carefully selecting the suitable cases for this treatment.
Direct pulp capping
dentine. It aims to maintain the pulp vitality and its normal responsiveness to electrical and thermal tests.2 On the other hand, an indirect pulp capping can also be performed when excavation of the pulpal caries can be stopped at stained but firm dentine, known as affected dentine. Calcium hydroxide lining is placed over the pulpal dentine prior to the placement of a definitive restoration.3 Q2. When is direct pulp capping indicated?
A. When a small (1 mm2), or involves contamination of any kind, it is better not to undertake pulp capping. It may also be contra-indicated to perform this treatment in case of systemic diseases (diabetes, cancer or blood disorders).1,4 Q4. Is direct pulp capping a suitable treatment for primary teeth?
A. In general, direct pulp capping treatment is recommended for permanent teeth and not primary teeth because of the poor prognosis.5,6 The high failure rate of direct pulp capping in primary teeth is explained by undifferentiated mesenchymal cells in the primary pulp which may become odontoclasts, leading to internal resorption.5 This increase in resorption in primary teeth is also due to physiological root resorption that is already in progress and an increased blood supply is stimulated. The root resorption may not be visible radiographically in terms of root blunting.7 Q5.What is the most suitable restoration to place over a pulp-capped tooth?
A. After pulp capping, a hermetic seal against bacterial infiltration is essential to guarantee the success of the treatment. According to a retrospective study by Barthel et al, the placement of a definitive restoration within the first two days after pulp exposure contributed significantly to increase the survival rate of these teeth.8 Currently, the restoration of choice to cover the pulp-capping material is a RMGIC (Resin Modified Glass Ionomer Cement) prior to etching and bonding the enamel and dentine surfaces for a composite resin restoration. Glass ionomers provide resistance to acid etch, condensation pressure and dissolution.9 Q6. What materials are used for pulp capping?
There are four products commonly used for direct pulp capping; May 2014
frequently used products and their composition are summarized in Table 1. Calcium hydroxide (Ca(OH)2) is the most common direct pulp agent. For pulp capping it is used as a two-paste product. It has excellent antibacterial and disinfectant properties but a number of disadvantages, including its solubility in water and the fact that it does not seal the exposed pulp from the external environment and has poor mechanical properties. For these reasons, a protective base material, such as a RMGIC, is required to provide an adequate seal of the pulp.9 Mineral trioxide aggregate (MTA), developed at the University of Loma Linda (USA), to seal communications between the root canal system and the external tooth surface,10 has been recommended for direct pulp capping.11 It has fine hydrophilic particles mixed with sterile water, which results in a colloidal gel (pH of 12.5). This gel solidifies to a hard structure within approximately 4 hours with low or no solubility.12 MTA is antibacterial and biocompatible and has no mutagenic potential. Unlike calcium hydroxide it creates an excellent seal2 and does not need any additional protection. Two commercial forms of MTA are available on the dental market; ProRoot® MTA (grey and white, Maillfer, Dentsply, Switzerland) and MTA-Angelus (Angelus Soluções Odontológicas, Londrina, Brazil) introduced in 2001.13 The two commercial brands of MTA have similar chemical composition, although ProRoot® MTA presents a slightly higher percentage of bismuth oxide than MTA-Angelus.14 Also, the particles of the MTA-Angelus have relatively low circularity and wide size distribution and are less homogeneous than ProRoot® MTA.15 No statistically significant difference was found between the two brands of MTA when cytotoxic effects on human endothelial cells were tested.12 Tri-calcium phosphate is another pulp-capping agent mainly indicated in bone regeneration procedures as it promotes osteoblastic formation of hard tissue. Alpha-tricalcium phosphate (α-TCP), a powder of apatite ceramics, is mixed with a saline or low acid solution and converted into hydroxyapatite or octacalcium phosphate. It sets and hardens at room temperature. Studies have shown that dentinal bridge formation occurs by direct
apposition on the pulpal wall. The bridge is contiguous to the pulp, thick and has minimal pulpal inflammation effect with no necrotic layer. The odontoblasts were present directly under, and in contact with, the bridge.16,17 However, the hard tissue barrier formation was reported to be slower than that with Ca(OH)2.17 Bio-Aggregate® (Innovative Bioceramix Inc IBC, Canada) is a root canal repair material composed of Bio-ceramic nano-particles. It is indicated in the repair of root perforations and root resorption, in apexification procedures and as a direct pulp-capping agent. It presents as pure white powder and liquid mixed together to form a thick paste-like mixture. MTA and Bioaggregate have similar chemical composition with some differences; Bioaggregates contain tantalum oxide instead of bismuth oxide in the MTA.18 Recently, Septodont launched Biodentine™, an Active Biosilicate Technology™ and a calcium silicate-based cement (Ca3SiO5-based cement) developed as a dentine substitute. Besides the usual endodontic indications of this class of calcium-silicate cements (repair of perforations, or resorption, apexification, and retrograde root-end filling), Biodentine™ is indicated in the restoration of deep or large crown carious lesions as it provides a very tight seal, without post-operative sensitivity, and ensures the longevity of restorations in vital teeth. Biodentine™ is mixed in any triturator with a minimum speed of 4,000 rpm (Figure 1). Figure 2 shows a pulp-capping case using BiodentineTM. After 6 weeks, the vitality of the pulp is checked and part of the BiodentineTM is partially removed and a ClI cavity is prepared using a pear-shaped diamond bur. The cavity is then restored conventionally using an adhesive system and resin-based composite. Q7. What is the physiological process of dentine bridge formation?
A. When applied over an exposed pulp, the pulp-capping agent causes a series of inflammatory responses leading to the formation of a hard-calcified dentine bridge. Owing to a high pH (12.5), calcium hydroxide causes liquefaction necrosis of the superficial pulp removing up to 1.5 mm of the inflamed tissue. This is followed by the neutralization of toxicity in DentalUpdate 299
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Generic Material Commercial Products
Manufacturer
Composition
Presentation
Ca(OH)2 Dycal® Dentsply- Caulk, USA
1,3-Butylene glycol disalicylate Zinc oxide Zinc oxide Calcium phosphate Calcium tungstate Iron oxide pigments
Base (Paste)
Life® Kerr, CA, USA
Calcium hydroxide N-ethyl-o/p-toluene sulfonamide Zinc oxide Titanium dioxide Zinc stearate Iron oxide pigments (dentine shade)
Catalyst (Paste)
Calcium hydroxide Zinc oxide Butyl benzene sulfonamide
Base (Paste)
Barium sulphate Titanium dioxide Methyl salicylate
Catalyst (Paste)
MTA ProRoot®MTA Dentsply, USA Tricalcium silicate Powder Tricalcium aluminate Tricalcium oxide Silicate oxide H2O MTA-Angelus® Angelus, Londrina, Calcium compounds Powder Brazil Distilled water Biosilicate Biodentine™ Septodont, USA
Tri-calcium silicate (C3S) Main core material Di-calcium silicate (C2S) Second core material Calcium carbonate and oxide filler Iron oxide shade Zirconium oxide Radiopacifier
Powder in capsules
Calcium chloride accelerator Hydrosoluble polymer water reducing agent
Liquid in single-dose pipettes
Bioaggregate Bio-Aggregate® Innovative Calcium silicate hydrate Powder BioCeramics (IBC), Calcium hydroxide Canada Hydroxyapatite Tantalum oxide Amorphous silicon oxide Deionized water Liquid Table 1. Direct pulp-capping products available on the market and their compositions.
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a
b
of the cavity first, moving circumferentially, removing the deepest remaining caries closest to the pulp last. In this way, an inadvertent exposure would be in a clean caries-free field. The exposure should be cleansed with 3% sodium hypochlorite. This will act as a bactericidal agent without causing an adverse pulpal reaction. Control of pulpal haemorrhage can be achieved with light pressure using a dry cotton pellet. Alternatively, the cotton pellet may be moistened with sodium hypochlorite, saline or local anaesthetic without epinephrine, ferric sulphate or slurry of calcium hydroxide.20,21 Q9. Is the placement of rubber dam mandatory during pulp capping?
c
A. Rubber dam will reduce bacterial contamination of an exposed pulpal site and provide an appropriate environment for successful resin bonding, creating a good seal. Q10. Is pulp capping influenced by a patient’s age and gender?
Figure 1. (a) Biodentine™ pack containing powder and liquid. (b) Adding water to Biodentine™ powder. (c) Mixed Biodentine™.
the deep layers with coagulative necrosis, which irritates the adjacent pulp and causes a minor inflammation leading to the formation of the dentine bridge. (This causes stimulation of the pleuripotential pulpal cells, which differentiate into odontoblasts, and these in turn lay down a calcified dentine bridge). Investigators have reported that MTA induces pulpal cell proliferation, cytokine release, hard tissue formation and the synthesis of an interface with dentine similar to hydroxyapatite composition.19 Q8. What is the best technique for cavity disinfection and haemorrhage control prior to pulp capping?
A. It is important to avoid bacterial contamination of the pulp exposure in order to allow and promote healing. Caries should be removed at the periphery
302 DentalUpdate
A. A patient’s age has an influence on the success or failure rate of pulp capping. Bogen et al found, in an observational study, that pulpal repair and pulp-capping success appears to be more favourable in young patients.19 This success may be attributed to the presence of larger apical foramina and greater vascularization of the pulp. An increased blood flow allows for better immune cell surveillance and response.19 On the other hand, the success of pulp capping is not dependent on patient gender.22 Q11. Are resin adhesive systems indicated for pulp capping?
A. The sealing potential of resin adhesive systems makes them an attractive alternative for direct pulp capping, preventing bacteria from entering the pulp. However, Stanley and Pameijer found that the application of acid to exposed pulps caused haemorrhage that was difficult to control.23 It is difficult to achieve an effective resin seal under such conditions, and consequently poor results were obtained. Modena et al also agree that adhesives result in lower pulp healing and induce chronic inflammation, even in the absence of bacteria. Inflammation is a poor environment
for pulp healing; a pulp inflamed due to caries will have decreased healing capacity.24 According to Cui et al, selfetching adhesives are relatively toxic to pulp tissue. This may be due in part to poor marginal sealing at the tissue-material interface.25 Another issue when placing adhesives directly on the pulp is the heat generated by the light-curing devices. It has been shown that an intrapulpal temperature increase of more than 11°C can lead to irreversible pulp damage.26 It can be concluded that resin adhesives are therefore not suitable as a direct pulp-capping agent. Q12. How long do you need to wait to be sure of direct pulp-capping success?
The literature is divided on when to measure the successful outcome of direct pulp capping. Some publications demonstrated that the survival rate of directly capped pulp tissue, using calcium hydroxide, decreases over time when compared to shortterm evaluations and the most unfavourable treatment outcomes occur within the first year after the treatment. According to the European Society of Endodontology, direct pulp capping should be assessed no longer than six months post-operatively and then at five yearly intervals.29 Matsuo et al suggested that the necessary interval for an adequate post-operative follow-up examination is 21 months.30 It is obvious that long-term outcomes (10 years) are the most relevant for the patients but, for convenience, in most of the clinical studies, the evaluation period is shorter. Success rates of direct pulp capping in a carious field have varied, depending on the technique and materials.8,22,27,28,29,30 In humans, success rates ranged between 13% and 98% in 1–10 year retrospective studies using calcium hydroxide (Table 2). Q13. What are the tests for controlling and monitoring a pulp-capped tooth?
A. Follow-up of pulp-capped teeth includes clinical and radiographical examinations. During recall appointments, patients’ self-reports concerning pain and sensitivity are recorded and pulp-capped teeth are tested with a cold stimulus. Radiographs are taken to evaluate reparative dentine formation, pulpal calcification, continued normal root development and May 2014
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Authors
Sample Size
Time Elapsed
Success Rate
Armstrong and Hoffman(1962)27
46
2–16 months
97.8%
Heyduck and Wagner (1978)
210
1-5 years
61.4%
Haskell et al (1978)29
149
5 years
87.2%
Matsuo et al (1996)30
44
Group with follow-ups for 3–18 months
80–83%
Group with follow-ups for 21 months
91.7%
Group with follow-ups for 24 months
100%
Barthel et al (2000)8
5 years
37%
10 years
13%
Al-Hiyasat et al (2006)
5 years
59.3%
28
123
22
204
Table 2. Evaluation of the success rate of pulp-capping techniques.
a
e physiological development and formation of a root end.32 Other authors have reported a high level of success using partial pulpotomies in caries exposures.33,34
b
c
d
Figure 2. (a) Deep caries resulting in direct pulp exposure. (b) BiodentineTM applied over the exposed pulp and in all the cavity (its setting time is 10 min); (c) 6 weeks later; (d) part of the BiodentineTM is removed. (e) Final composite restoration.
the absence of pathosis, such as internal root resorption and apical periodontitis.31 The marginal integrity of the final restorations should always be evaluated.19 Clinical signs indicative of a favourable outcome are a normal response to pulp sensitivity tests, absence of pain or tenderness to percussion and absence of swelling, sinus tract and pathological mobility. Also, in anterior teeth, absence of tooth discoloration is the most important factor to be considered.31,7 Q14. Can you carry out a partial pulpotomy on permanent teeth?
Partial pulpotomy is the removal of a small portion of the vital coronal pulp and preserving the vitality of the remaining coronal and radicular pulp tissue. This technique is preferred in order to encourage May 2014
Q15. What are the future trends and perspectives for direct pulp capping?
A. Novel techniques are being developed to regenerate rather than to restore lost hard dental tissue, including enamel, dentine and pulp tissue. The regeneration of dentine is considered feasible as it is in direct contact with a highly vascularized and innervated pulpal tissue. Odontoblastic cells in the pulp continue to produce secondary dentine, even after tooth eruption at low level, and they secrete tertiary dentine as a repair reaction with the help of progenitor cells that will be, at this point, triggered to differentiate into odontoblastic-like cells under the influence of specific growth factors. Research on pulpal tissue regeneration is based on growth factor delivery, stem cell delivery and geneenhanced tissue regeneration. With growth factor delivery, TGF-beta 1 (polypeptide responsible for the control of cell growth, cell proliferation, cell differentiation and apoptosis) is implanted intra-pulpally to induce odontoblastic-like cell differentiation and reparative dentine formation; nevertheless its action is limited. Other growth factors, such as insulin-like growth factor in mechanically exposed DentalUpdate 303
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pulps, have been reported. This will reduce inflammation, preserve tooth vitality and promote pulp repair.35 Future trends on pulp capping also include the use of lasers, more specifically CO2 Laser, which was found to have anti-inflammatory, cell biostimulation and decontamination effects on pulpal cells and dentine.36 CO2 Laser used in direct pulp capping was found to increase the percentage of pulp vitality preservation and the thickness of the dentinal bridge newly formed after pulp exposure significantly.36
7.
8.
9.
10.
Summary
11.
Preservation of the vitality of a tooth is the aim of the restorative clinician. However, the clinician is often faced with a direct pulp exposure as a result of the operative procedure or trauma. Criteria for success are outlined in this paper using an easy reference design.
12.
13.
Conclusion Direct pulp capping, although a very technique and case selection sensitive procedure, is considered to be a basic conservative approach and, when it is found to be indicated, should be performed. The high success rate found after a long-term evaluation, and the variety of products that ensure such a rate, are plus factors when considering direct pulp capping.
References 1. 2.
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D
21. Hafez AA, Cox CF, Tarim B, Otsuki M, Akimoto N. An in vivo evaluation of hemorrhage control using sodium hypochlorite and direct capping with a one- or two-component adhesive system in exposed nonhuman primate pulps. Quintessence Int 2002; 33: 261–272. 22. Al-Hiyasat A, Barrieshi-Nusair KM, Al-Omari MA. The radiographic outcomes of direct pulp-capping procedures performed by dental students: a retrospective study. J Am Dent Assoc 2006; 137: 1699–1705. 23. Stanley HR, Pameijer CH. Dentistry’s friend: calcium hydroxide. Oper Dent 1997; 22: 1–3. 24. Modena KC da Silva, Casas- Apayco LC, Atta MT. Cytotoxicity and biocompatibility of direct and indirect pulp capping materials. J Appl Oral Sci 2009; 17(6): 544–554. 25. Cui C, Zhou X, Chen X, Fan M, Bian Z, Chen Z. The adverse effect of self-etching adhesive systems on dental pulp after direct pulp capping. Quintessence Int 2009; 40(6): 26–34. 26. Zach L, Cohen G. Pulp response to externally applied heat. Oral Surg Oral Med Oral Pathol 1965; 19: 515–530. 27. Armstrong WP, Hoffman S Pulp cap study. Oral Surg Oral Med Oral Pathol 1962; 15: 1505–1509. 28. Heyduck G, Wegner H. Stomatol DDR. 1978; 28(9): 614–619. German. 29. Haskell EW, Stanley HR, Chellemi J, Stringfellow H. Direct pulp capping treatment: a long-term followup. J Am Dent Assoc 1978; 97(4): 607–612. 30. Matsuo T, Nakanishi T, Shimizu H, Ebisu S. A clinical study of direct pulp capping applied to cariousexposed pulps. J Endo 1996; 22(10): 551–556. 31. European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. Int Endo J 2006; 39: 921–930. 32. Cvek M. A clinical report on partial pulpotomy and capping with calcium hydroxide in permanent incisors with complicated crown fracture. J Endod 1978; 4: 232–237. 33. Ward J. Vital pulp therapy in cariously exposed permanent teeth and its limitations. Aust Endod J 2002; 28: 29–37. 34. Aguilar P, Linsuwanont P. Vital pulp therapy in vital permanent teeth with cariously exposed pulp: a systematic review. J Endod 2011; 37: 581–587. 35. Edwards PC, Mason JM. Gene-enhanced tissue engineering for dental hard tissue regeneration: (2) dentin-pulp and periodontal regeneration. Head Face Med 2006; 2: 16. 36. Nammour S, Tielemans M, Heysselaer D, Pilipili Ch, De Moor R, Nyssen-Behets C. Comparative study on dogs between CO2 laser and conventional technique in direct pulp capping. Rev Belge Med Dent 2009; 64(2): 81–86.
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