Clinical evaluation of mineral trioxide aggregate and biodentine as direct pulp capping agents in carious teeth.

BACKGROUND: Root canal treatment has been a routine treatment option for carious exposure of the dental pulp. In the context of minimally invasive dentistry, direct pulp capping (DPC) procedure with a reliable biomaterial may be considered as an alternative provided the pulp status is favorable. Mineral trioxide aggregate (MTA), a bioactive cement with excellent sealing ability and biocompatibility is capable of regenerating relatively damaged pulp and formation of dentin bridge when used as DPC agent. Biodentine is comparatively a new biomaterial claimed to possess properties similar to MTA and is currently explored for vital pulp therapy procedures. AIM: The aim of the present study was to evaluate the clinical response of pulp-dentin complex after DPC with MTA and biodentine in carious teeth. SUBJECTS AND METHODS: Twenty-four permanent molars with carious exposure having no signs and symptoms of irreversible pulpitis were selected and assigned to one of the two groups, Group I - MTA and Group II - biodentine. Patients were recalled at 3 weeks, 3 months, and 6 months for clinical and radiographic evaluation. Fisher's exact test was used along with Chi-square test for statistical analysis.
RESULTS: Over a period of 6 months, MTA and biodentine showed 91.7% and 83.3% success rate, respectively, based on the subjective symptoms, pulp sensibility tests, and radiographic appearance.
CONCLUSION: MTA and biodentine may be used as DPC agents when the pulpal diagnosis is not more than reversible pulpitis.

INTRODUCTION

Vital pulp therapy has been performed to maintain the vitality of pulp exposed due to iatrogenic errors or trauma.[1] In deep carious lesions, inflammation is confined to superficial pulp, whereas tissue deep inside the pulp remains normal, except for some dilated blood vessels.[2] It has been reported that pulp healing can be achieved even after a carious exposure if the inflammation is no more severe than reversible pulpitis.[3] Endodontic therapy has been the traditional approach in managing pulpal exposure encountered during caries excavation as placement of medicaments against cariously exposed pulp was controversial.[4] The hesitancy to place a capping material on a carious exposure is due to incompetence in identifying a reliable nonabsorbable bioactive material with a predictable outcome.

Several materials have been experimented with for capping vital pulp. Although Ca(OH)2 has been the material of choice for pulp capping, it has several disadvantages, namely, unsatisfactory adherence to dentin, dissolution over time, and multiple tunnel defects in the dentin bridges.[5] Mineral trioxide aggregate (MTA) is recommended as an alternative for Ca(OH)2 as the stimulation of dentin-bridge formation is faster allowing pulp healing and showed high success rates in clinical procedures.[2] MTA is a bioactive, biocompatible, antibacterial material with good stability, and excellent sealing ability.[2] However, its long setting time, poor handling properties, high material cost, and the discoloration potential remain a challenge to the practitioner.[6] Slower setting[7] and discoloration of dental tissues[8] were also seen with white MTA (WMTA) that was introduced to overcome the discoloration potential of gray MTA. Nevertheless, MTA has been shown to be a reliable direct pulp capping (DPC) material on carious exposures in permanent teeth when two-visit treatment protocol was observed.[3]

Biodentine (Septodont, Saint Maur de Fosses, France) is a new calcium-silicate-based restorative cement, which can be used as a dentin substitute and has similar applications as MTA. It encourages the vital pulp cells and stimulates reparative dentin formation when in direct contact with pulp tissue.[9] The consistency of biodentine is similar to that of phosphate cement. The material can be directly applied in the cavity as bulk dentin substitute without preconditioning and has a shorter setting time.[9]

Both MTA and biodentine have demonstrated favorable results when used as DPC agents in mechanically exposed pulps;[10] to our knowledge, there is limited clinical literature comparing biodentine and MTA as DPC agents in carious teeth. Hence, the aim of the study was to evaluate the clinical response of pulp-dentin complex after DPC with MTA and biodentine in carious teeth.

SUBJECTS AND METHODS

In the present study, all patients in the age group of (18–40) years who were referred to the department for the management of deep dental caries in molars were selected. Teeth that were asymptomatic, responded positively to thermal and electrical tests with no tenderness on percussion, and with no pathologic changes on periapical radiographs were selected. Clinically, all teeth exhibited either primary or secondary deep caries. Radiographically, all teeth showed deep dental caries approaching pulp with no evidence of thickened periodontal ligament, furcation radiolucencies, or periradicular pathosis.

Patients were treated in accordance with Helsinki declaration. Informed consent was obtained after explaining the experimental rationale, clinical procedures, and possible complications of the procedure.

A standardized operative procedure was followed and performed by a single operator. Before cavity preparation, teeth were mechanically cleaned and disinfected with 0.2% chlorhexidine solution. After adequate anesthesia with 1:100,000 lignocaine hydrochloride with adrenaline (xylocaine) and rubber dam application, superficial caries and overhanging enamel were removed with sterile diamond points at high speed under air-distilled water spray coolant. Care was taken to excavate all the soft caries near the pulp with spoon excavators and round carbide burs on a slow speed handpiece. A sterile cotton pellet damped in 3% NaOCl was placed onto the pulp exposure sites to achieve hemostasis. Teeth which had no exposure and pulps which bled profusely were excluded from the study. In total, 24 teeth with pulp exposure which satisfied the inclusion criteria were selected.

Patients received either of the two treatment modalities using allocation concealment method.

Group I: MTA (n = 12)

Group II: Biodentine (n = 12).

In Group I, exposed pulp and surrounding dentin were capped with a 2 mm thick layer of ProRoot WMTA, manipulated according to manufacturer's recommendations. After placing MTA, a wet cotton pellet was placed directly over the material and the tooth was provisionally restored with zinc polycarboxylate cement [Figure 1].

Figure 1

(a) Pulp exposure following caries excavation. (b) Mineral trioxide aggregate placed over the exposed pulp. (c) Radiograph showing mineral trioxide aggregate placement immediately after pulp capping. (d) Six months follow-up radiograph

In Group II, pulps of teeth were capped with biodentine, manipulated according to manufacturer's recommendations and it was left as a temporary restoration [Figure 2].

Figure 2

(a) Pulp exposure following caries excavation. (b) Biodentine placed over the exposed pulp and as temporary restoration. (c) Radiograph taken immediately after biodentine placement. (d) Six months follow-up radiograph

Patients in both the groups were asked to return for clinical evaluation and placement of definitive composite restoration after 3 weeks. In Group I, cotton pellet was removed followed by resin-modified glass ionomer cement base and composite restoration was given. In Group II, biodentine was reduced to base followed by composite restoration. In Class II restorations, contact was established using palodent matrix system.

Patients were recalled at 3 months, 6 months, and 1 year for evaluation. Patients were asked about any postoperative sensitivity and pain throughout the study period. Thermal and electric pulp sensitivity testing were performed to assess pulp health and Image J software (1.4 version, Informer Technologies, Inc) was used to detect the formation of dentin bridge on the postoperative radiographs.

Statistical analysis

SPSS (version 20, SPSS Inc, Chicago) was used for analysis. Descriptive and analytical statistics were calculated. Pearson correlation coefficient was used. Fisher's exact test was used along with Chi-square test as the values in some of the cells were <5. P < 0.05 was considered statistically significant.

RESULTS

Three patients (two with biodentine and one with MTA) complained of spontaneous pain, within 3 weeks and were root canal treated. Other patients were asymptomatic during the experimental time period and were sensitive to cold and electric tests [Graph 1]. At 6-month follow-up, none of the teeth developed periapical pathology [Graph 2]. In addition, two teeth from MTA and two teeth from biodentine group showed definite dentin-bridge formation at 1-year follow-up.

Graph 1

Comparing pulp response to pulp sensibility tests at 3 weeks, 3 months, and 6 months between mineral trioxide aggregate and biodentine groups

Graph 2

Comparing radiographic response to mineral trioxide aggregate and biodentine at 3 weeks, 3 months, and 6 months

Out of 24 teeth, 14 teeth had occlusal caries and ten teeth had proximal caries. Among the three teeth that were root canal treated, one had occlusal caries and two with proximal caries. At 6 months follow-up, the overall pulp survival rate for MTA and biodentine was 91.7% and 83.3%, respectively.

The correlation was significant at 6 months for vitality and X-ray findings, vitality and presence of dentin bridge, and presence of dentin bridge and X-ray findings.

DISCUSSION

DPC attempts healing of the exposed pulp which is reversibly damaged by stimulating the formation of dentin bridge, thereby restoring the structure and function of pulp-dentin complex.[8] Incomplete caries removal has shown a lower success rate of 56.2% for DPC with MTA on long-term basis.[11] The success of vital pulp therapy depends on the complete removal of disintegrated tissue, and controlling the infection is crucial for success of the procedure.[12] Hence, in the present study, care was taken to ensure complete excavation of caries.

The treatment was regarded as successful when none of the following signs or symptoms were present: Spontaneous pain, tenderness on percussion, swelling, fistulation, pathological mobility, furcation radiolucency, periodontal ligament space widening, or internal and external root resorption.[13] However, dentin-bridge formation is a key for final healing and long-term success as it protects the exposed pulps to further attacks of oral bacteria that may result in pulp degeneration, atrophy, and shrinkage.[14] It has been shown that periapical radiograph is incapable of detecting dentin bridge <0.5 mm thick.[15] In the present study, dentin-bridge formation was evident in two teeth from MTA and two from biodentine group that were followed up for 1 year. Moreover, two teeth from Group II and one tooth from Group I underwent root canal treatment as patients returned with persistent symptoms within the 3 months follow-up. Among the failed teeth, two teeth had proximal caries and one tooth had occlusal caries. Marques et al. in their study observed a lower success rate of DPC on axial wall. This they attributed to the lower marginal seal and subsequent microleakage in proximal restorations.[16] The overall pulpal survival was established by subjective symptoms, cold test, and radiographs taken at recall appointment. MTA had a success rate of 91.7% which is comparable to the success rate of MTA at 97.96% seen in other study.[17] The success rate for biodentine in the present study was 83.3%.

High success rate for MTA is attributed to its ability to stimulate the formation of dentin bridge, antibacterial property, and excellent sealing ability, which is critical for the success of DPC procedure.[18] It also stimulates the production of cytokines in human osteoblasts, allows good adherence of the cells to the material, thereby playing an active role in dentin-bridge formation.[19] Capping of the pulpotomized teeth with biodentine also produced a similar pulp response. However, the thickness of dentin bridge formed subjacent to biodentine was greater. Compared to MTA, it has a shorter setting time which is also an advantage.[20] Similarity of the tissue response with these materials may be due to their similar chemical composition (tricalcium silicate), the by-product released during setting reaction,[21] and physical properties.[22]

Bleeding from the exposed pulp for longer than 5 and up to 10 min is used as a threshold for reversible versus irreversible pulpitis classification.[17] In our study, pulp capping agent was placed only after achieving complete hemostasis with 3% NaOCl. However, one case which took more than 5 min for hemostasis, returned with severe pain within the next follow-up. MTA showed discoloration in majority of the cases. It has been shown that WMTA induced color change at 1 week time which increased over time, whereas biodentine did not affect the stability of tooth color.[23] The bismuth oxide component in WMTA, NaOCl used for hemostasis or curing light used for composite restoration may be responsible for this discoloration.[24]

The study was performed in carious pulp exposures that relied on the subjective symptoms, pulp sensibility test, and radiographic examination. Long-term clinical studies are required to substantiate the observations of the present study.

CONCLUSION

Within the limitations of the study, it can be concluded that MTA and biodentine are reliable DPC agents. Careful case selection, isolation, complete caries excavation, pulp capping, and proper restoration will contribute to the success of the treatment and help maintain the vitality of the tooth.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.