Treatment Options for the Exposed Vital Pulp
Edward J. Swift, DMD, MS
Dental pulp can be exposed by accidental trauma to a tooth or by the clinician during cavity preparation. In the latter situation, even when the exposure is diagnosed as mechanical rather than carious, the pulp typically is inflamed because caries was present in the tooth. While pulpectomy and root canal therapy represent the appropriate treatment of frank carious exposures, the proper treatment of mechanically exposed pulps has been a controversial subject for many years. This article describes the indications, clinical techniques, and prognosis for two types of vital pulp therapy: direct pulp capping and partial pulpotomy.
Vital pulp therapy has a high success rate if the following conditions are met:
•The pulp is not inflamed.
•The restoration seals out bacteria.
•A nontoxic pulp dressing is applied.
The presence of healthy pulp is an essential requirement for successful treatment of an exposure. While studies have suggested that capping of inflamed pulps can be successful,1,2 such treatment affords an inferior success rate.3,4 If the pulpal tissue at the site of the exposure is not healthy, the use of a partial pulpotomy technique should be considered.
Along with pulpal health, provision of a seal against bacterial ingress is presumably the most critical factor in the success of vital pulp therapy. Challenge by bacteria during the healing phase will cause failure. If the exposed pulp is effectively sealed from bacterial leakage, however, successful healing with a hard tissue barrier can occur with a wide variety of pulp dressings.5,6
Calcium hydroxide--an antibacterial agent that disinfects the superficial pulp--has traditionally been the most common dressing applied to exposed pulps.7 Due to its high pH (~12.5), pure calcium hydroxide causes liquefaction necrosis of the superficial pulp, thus removing approximately 1.5 mm of inflamed pulp tissue. Neutralization of the high pH in deeper layers of the pulp results in coagulation necrosis at the junction of necrotic and vital tissues, with only a mild irritation to the pulp. This minor irritation stimulates an inflammatory response that, in the absence of bacteria, heals with a hard tissue barrier.8 While hard-setting calcium hydroxide pastes are less caustic and do not necrose the superficial pulp, these materials have demonstrated the ability to initiate the same type of healing as calcium hydroxide powder.9
A principal disadvantage of calcium hydroxide materials is that they do not seal the exposed pulp from the external environment. The failure of calcium hydroxide to seal the pulp may be a particular complication with composite resin restorations, where polymerization shrinkage could draw the pulp cap away from the surface.10 Therefore, an additional base material can be placed to help ensure that bacteria do not enter the pulp during the healing phase. Although materials such as zinc oxide eugenol, tricalcium phosphate, and resins have been proposed as dressings for vital pulp therapy, none has demonstrated the predictability of calcium hydroxide used in conjunction with a well-sealed coronal restoration.
Some investigators state that alternatives to calcium hydroxide should be considered since dentin bridges beneath calcium hydroxide pulp caps contain tunnel defects that leave the pulp vulnerable to recurring bacterial infection via microleakage.11 Researchers also note that calcium hydroxide materials tend to soften, disintegrate, and erode over time, thus resulting in voids and potential pathways for bacterial infiltration.12
The search for alternatives to calcium hydroxide currently focuses on resin adhesives or dentin bonding systems.13 Phosphoric acid is used by the majority of the contemporary bonding systems to etch enamel and dentin, removing the smear layer and opening the dentin surface to penetration by hydrophilic resin monomers. The surface is infiltrated by resin monomers that copolymerize with hydrophobic resin monomers to seal the dentin surface.10,14-17 The sealing potential of these systems makes them attractive alternatives for direct pulp capping. Resin pulp capping has already gained popularity among clinicians, although most probably select this technique primarily on the basis of anecdotal evidence.18 Scientific evidence based on animal studies5,19-22 and limited human testing,23 however, supports the use of resin adhesives as pulp-capping agents. Studies suggest that hemorrhage control and prevention of bacterial ingress are critical to the success of pulp capping, and that resin adhesives can provide the necessary seal.21
The research community, however, remains divided on this subject. Pameijer and Stanley reported a primate study in which calcium hydroxide pulp capping was far more successful than resin pulp capping.24 These investigators observed that etching of the exposed pulp caused a hemorrhage that was difficult to control. Achieving an effective resin seal under such conditions is problematic, and the lack of a seal undoubtedly contributed to their compromised results. In addition, some resin systems may seal the pulp more effectively than others, so success may be material-dependent to an extent.25
It must be noted that the studies that support resin pulp capping have typically involved exposure and capping of normal, uninflamed pulps. Since resins lack the inherent hemostatic and bactericidal properties of calcium hydroxide, success rates with inflamed pulps might be significantly reduced. Calcium hydroxide has demonstrated the ability to suppress bacterial infection of mechanically exposed pulps open to the oral environment for 24 h, which allowed a normal healing response.
Direct Pulp Capping
The term "pulp capping" refers to the placement of a dressing directly onto an exposed pulp. The indications for pulp capping include teeth with recent (< 24 h) traumatic or mechanical exposures. Pulp capping should be used only for immature permanent teeth or for mature permanent teeth with simple restorative needs. For example, a tooth that will serve as an abutment for a fixed partial denture would be optimally treated by a more predictable method (eg, root canal therapy). Mature teeth with inflamed pulps (ie, carious pulp exposures) should not be pulp-capped.
Once the patient has been anesthetized, a rubber dam should be placed and the exposed dentinal surface rinsed. The tooth should be disinfected with a chlorhexidine solution and the pulp gently rinsed with anesthetic or sterile saline. If any hemorrhage occurs, dabbing with a sterile cotton pellet can be performed until the hemorrhage ceases. Pure calcium hydroxide is subsequently mixed with sterile water, saline, or anesthetic solution, and directly applied to the exposure site. The pulp should then be gently rinsed with anesthetic or sterile saline and a resin-modified glass ionomer base/liner material should be applied and light cured to protect the calcium hydroxide dressing and establish an additional seal. Finally, an adhesive bonding system should be used to seal the cavity preparation and restore the tooth with an appropriate filling material (Figure 1).
The tooth should be evaluated using electrical pulp testing (EPT), thermal testing, and palpation and percussion tests at 3 to 4 weeks, 3 months, 6 months, 12 months, and every year thereafter. Periodic radiographs are necessary to detect the presence of periapical radiolucencies and for continued development of immature teeth at the root. Hard tissue barriers can occasionally be observed at the treated exposure site as early as 6 weeks posttreatment.
The success of pulp capping relies on the ability of calcium hydroxide to disinfect the superficial pulp and dentin and to necrose the superficial inflamed pulp. The quality of the bacteria-tight seal provided by the base, bonding system, and restoration is also of critical importance. The reported prognosis for pulp capping is in the range of 80% when performed under ideal conditions (ie, uninflamed pulp and proper coronal seal).26,27
The term "partial pulpotomy" or "Cvek pulpotomy" describes the removal of coronal pulp tissue to the level of the healthy pulp.28 A sterile diamond bur rotating at high speed under copious irrigation is used to make a surgical excision of the inflamed pulp tissue. The excision is considered complete when the pulp stump no longer bleeds excessively. While pulpotomies have been routinely used in treatment of primary and young permanent teeth following traumatic pulp exposure, the use of pulpotomies to treat carious exposures--particularly in mature permanent teeth--is a more recent concept. The rationale for this procedure is that if this inflamed tissue is removed, the healthy underlying tissue is more likely to maintain its health and seal the exposure with hard tissue bridging of the exposure site (assuming that the requirements of a bacteria-tight seal are satisfied).
The indications for a partial pulpotomy are similar to those for pulp capping--an immature permanent tooth or a mature permanent tooth that requires simple restoration are the preferred candidates. A partial pulpotomy may be selected over pulp capping when more extensive pulpal inflammation is expected, as in traumatic exposures older than 24 h and for mechanical exposures in teeth with deep caries (Figure 2). While not scientifically proven, this technique might also be useful in teeth with a frank carious exposure when the patient might otherwise select extraction over root canal therapy and extensive coronal restoration.
Anesthesia, isolation, and surface disinfection should be accomplished in the aforementioned manner (Figure 3). At the exposure site, 1 mm to 2 mm of the superficial pulp tissue should be removed with a high-speed diamond bur under copious water irrigation (Figure 4).29 If excessive bleeding continues, the preparation can be extended apically. Any excess blood can be removed by rinsing with sterile saline or anesthetic solution and drying with a sterile cotton pellet. Care must be exercised to prevent the formation of a blood clot, which compromises the prognosis.28
If the pulp is sufficiently large to allow an additional 1 mm to 2 mm of necrosis, a thin layer of pure calcium hydroxide should be mixed and applied. If the pulp cannot accommodate further loss of tissue, a hard-setting calcium hydroxide liner should be mixed and applied (Figure 5). As in pulp-capped teeth, an appropriate base, dentin/enamel bonding system, and restorative material should be placed. Follow-up examinations must be scheduled using the time intervals and procedures described for pulp capping (Figure 6).
Partial pulpotomy offers several advantages over conventional pulp capping. Superficial inflamed pulp tissue is removed during preparation of the pulpal cavity. Calcium hydroxide disinfects the pulp and dentin and removes additional inflamed pulp tissue. Most importantly, the technique provides space for materials to provide a bacteria-tight seal that allows pulpal healing to occur under optimal conditions. While the prognosis for success of partial pulpotomies is approximately 95%,28,30 this rate applies to traumatized teeth where the level of pulpal inflammation is predictable. The success rate for treatment of carious exposures (Figures 7-8-9) is currently under investigation, but remains undetermined at present.
In order to perform pulp capping with predictability and success, the clinician must perform the technique on an uninflamed pulp. In the restorative process, it is similarly critical to achieve a proper seal that prevents bacterial invasion and to use a capping material that is biocompatible with the pulp. This article has discussed several technical and material considerations that must be addressed during vital pulp therapy and highlights two pulp-capping techniques that may afford an optimal prognosis when they are utilized for the appropriate indications.
* Associate Professor and Graduate Program Director, Department of Operative Dentistry, University of North Carolina School of Dentistry, Chapel Hill, NC.
† Private practice, Philadelphia, PA.
- Cox CF, Bergenholtz G, Heys DR, et al. Pulp capping of dental pulp mechanically exposed to microflora: A 1-2 year observation of wound healing in the monkey. J Oral Pathol 1985;14(2):156-168.
- Fitzgerald M, Heys RJ. A clinical and histological evaluation of conservative pulpal therapy in human teeth. Oper Dent 1991;16(3):101-112.
- Tronstad L, Mjör IA. Capping of the inflamed pulp. Oral Surg Oral Med Oral Pathol 1972;34(3):477-485.
- Mjör IA, Tronstad L. The healing of experimentally induced pulpitis. Oral Surg Oral Med Oral Pathol 1974;38(1):115-121.
- Cox CF, Keall CL, Keall HJ, et al. Biocompatibility of surface-sealed dental materials against exposed pulps. J Prosthet Dent 1987;57(1):1-8.
- Cox CF, Sübay RK, Suzuki S, et al. Biocompatibility of various dental materials: Pulp healing with a surface seal. Int J Periodont Rest Dent 1996;16(3):240-251.
- Stanley HR, Pameijer CH. Dentistry's friend: Calcium hydroxide. Oper Dent 1997;22(1):1-3.
- Schröder U, Granath LE. Early reaction of intact human teeth to calcium hydroxide following experimental pulpotomy and its significance to the development of hard tissue barrier. Odontol Revy 1971;22(4):379-395.
- Stanley HR, Lundi T. Dycal therapy for pulp exposures. Oral Surg Oral Med Oral Pathol 1972;34(5):818-827.
- Goracci G, Mori G. Scanning electron microscopic evaluation of resin-dentin and calcium hydroxide-dentin interface with resin composite restorations. Quint Int 1996;27(2):129-135.
- Cox CF, Sübay RK, Ostro E, et al. Tunnel defects in dentin bridges: Their formation following direct pulp capping. Oper Dent 1996;21(1):4-11.
- Novickas D, Fiocca VL, Grajower R. Linings and caries in retrieved permanent teeth with amalgam restorations. Oper Dent 1989;14(1):33-39.
- Cox CF, Suzuki S. Re-evaluating pulp protection: Calcium hydroxide liners vs. cohesive hybridization. J Am Dent Assoc 1994;125(7):823-831.
- Van Meerbeek B, Inokoshi S, Braem M, et al. Morphological aspects of the resin-dentin interdiffusion zone with different dentin adhesive systems. J Dent Res 1992;71(8):1530-1540.
- Swift EJ, Hammel SA, Perdigão J, et al. Prevention of root surface caries using a dental adhesive. J Am Dent Assoc 1994;125(5):571-576.
- Suzuki S, Cox CF, White KC. Pulpal response after complete crown preparation, dentinal sealing, and provisional restoration. Quint Int 1994;25(7):477-485.
- Swift EJ, Perdigão J, Heymann HO. Bonding to enamel and dentin: A brief history and state of the art, 1995. Quint Int 1995;26(2):95-110.
- Kanca J. Replacement of a fractured incisor fragment over pulpal exposure: A long-term case report. Quint Int 1996;27(12):829-832.
- Onoe N. Study on adhesive bonding systems as a direct pulp capping agent. Jap J Conserv Dent 1994;37:429-466.
- Akimoto N, Momoi Y, Kohno A, et al. Biocompatibility of Clearfil Liner Bond 2 and Clearfil AP-X system on nonexposed and exposed primate teeth. Quint Int 1998;29(3):177-188.
- Cox CF, Hafez AA, Akimoto N, et al. Biocompatibility of primer, adhesive and resin composite systems on non-exposed and exposed pulps of non-human primate teeth. Am J Dent 1998;11(Special Issue):S55-S63.
- Tarim B, Hafez AA, Suzuki S, et al. Biocompatibility of Optibond and XR-Bond adhesive systems in nonhuman primate teeth. Int J Periodont Rest Dent 1998;18(1):86-99.
- Gwinnett AJ, Tay FR. Early and intermediate time response of the dental pulp to an acid etch technique in vivo. Am J Dent 1998;10(Special Issue):S35-S44.
- Pameijer CH, Stanley HR. The disastrous effects of the "Total Etch" technique in vital pulp capping. Am J Dent 1998;11(Special Issue):S45-S54.
- Tsuneda Y, Hayakawa T, Yamamoto H, et al. A histopathological study of direct pulp capping with adhesive resins. Oper Dent 1995;20(6):223-229.
- Fuks AB, Bielak S, Chosak A. Clinical and radiographic assessment of direct pulp capping and pulpotomy and young permanent teeth. Pediatr Dent 1982;4(3):240-244.
- Ravn JJ. Follow-up study of permanent incisors with complicated crown fractures after acute trauma. Scand J Dent Res 1982;90(5):363-372.
- Cvek M. A clinical report on partial pulpotomy and capping with calcium hydroxide in permanent incisors with complicated crown fracture. J Endod 1978;4(8):232-237.
- Granath L-E, Hagman G. Experimental pulpotomy in human bicuspids with reference to cutting technique. Acta Odontol Scand 1971;29(2):155-163.
- Fuks A, Chosak A, Eidelman E. Partial pulpotomy as an alternative treatment for exposed pulps in crown-fractured permanent incisors. Endod Dent Traumatol 1987;3(3):100-102.