Evaluation of Silver Diamine Fluoride as Indirect Pulp Capping Agent in Primary Teeth: An in vivo Study

Introduction

Introduction The treatment of deep carious lesions approaching healthy pulp has always been a challenge. Indirect pulp capping (IPC) is recommended for teeth that have deep carious lesions approximating the pulp with no signs or symptoms of pulp degeneration.¹ The ultimate objective of IPC is to arrest demineralization of carious dentin while preserving the pulp vitality and stimulating promotion of reparative dentin.²

Various materials have been used as IPC agents in the management of vital teeth with deep carious lesions. Calcium hydroxide (CH) has been a gold standard for pulp capping and is being used since its use was first described by Zander in 1939.³ It allows the formation of a reparative dentin through cellular differentiation, extracellular matrix secretion and subsequent mineralization.⁴ However, several disadvantages have been reported, including high solubility in oral fluids and the formation of tunnel defects in dentin bridges, leading to failure over time.⁵

Silver diamine fluoride (SDF) has also been used as a cariostatic agent. It helps in the deposition of silver phosphate to restore mineral content, resulting in re-hardening of tooth structure. It also releases fluoride.⁶

Comparative studies on the treatment of deep carious lesions have been previously performed on primary teeth. Only a few studies have compared the efficacy of CH and SDF in the treatment of deep carious lesions. So, the present study was planned to evaluate and compare effects of SDF with CH as an IPC agent in primary teeth.

Methods

A study proforma was designed which included demographic details, chief complaints, recording of all the subjective and objective symptoms, radiographic findings and the follow-up recordings. This clinical study was approved by ethical committee of the institution. Children of either gender in the age group of 4-10 years, having deep carious lesions in primary anterior and posterior teeth were evaluated for following inclusion and exclusion criteria.

Inclusion criteria:

The inclusion criteria were history of dull, reversible pain, Mild discomfort on chewing, and No radiographic changes in periapical / furcation area.

Exclusion criteria:

The exclusion criteria were Mobility, Internal/External resorption and Acute / Chronic systemic conditions Based on these, 34 teeth of 27 patients were selected for the study. All teeth were randomized into 2 groups. 38% SDF was used as IPC material for group 1 which consisted of 18 patients; and for group 2, Dycal was the material of choice which consisted of 16 patients.

All the procedures were performed by the standard method of IPC under rubber dam by a single operator.

After satisfactory caries excavation, cavity was dried with cotton pellets. For experimental group, 38 % SDF was applied at the base of the cavity for 3 minutes followed by rinsing for 30 seconds. After drying, cavity was restored with GIC Fuji IX [Fig. 1].

For control group, Dycal was applied at the base of the cavity according to manufacturer’s instructions. Cavity was then restored with GIC Fuji IX [Fig. 2].

Post-operative radiograph was taken on the same day. At follow up examination, detailed clinical and radiographic examination was performed after 1 week and 1 month. Upon clinical examination, patients were evaluated for the presence or absence of post-treatment signs or symptoms such as sensitivity, pain or swelling. Patients were also evaluated for the presence or absence of any pathologic changes radiographically.

Data was collected and statistical analysis was done using SPSS version 22. Chi-square test and Wilcoxon signed rank test was used. The level of significance was kept at 5%.

Results

A total of 33 teeth (SDF-17; Dycal-16) could be followed up at the end of 1 month, as 1 patient was lost during follow up examinations [Fig. 3].

There were no treatment failures reported in any case at 1 week followup [Table 1]. One patient reported with pain in mandibular first primary molar at 1 month which was treated with Dycal as an IPC material. Therefore, the clinical and radiographic success at 1 month was found to be 100% (17/17) with 38% SDF and 93.75% (15/16) in calcium hydroxide with no significant differences in success rates between two groups [Table 2].

Discussion

Indirect Pulp Capping procedure is based on the theory that a zone of affected, demineralized dentin exists between the outer infected layer of dentin and the pulp.⁷  IPC involves removal of the outer layer of carious dentin, thus eliminating majority of the bacteria from the lesion. When the lesion is sealed, the substrate on which the bacteria thrive to produce acid and cause subsequent demineralization is removed.⁸ Although carious dentin left in the tooth probably contains few bacteria, the number of these bacteria is greatly diminished when it is covered with a suitable IPC material. Further, if the pulp capping material can denature the softened carious dentin and also promote its remineralization, the micro-environment in the tooth will tilt toward regeneration in the form of laying down of reparative/tertiary dentin.⁹

The success of IPC is determined clinically by asymptomatic, vital teeth and histologically by tertiary dentin deposition adjacent to the site of injury. All the events such as method of preparation, condition of the dentin-restoration wall, presence of bacteria, type of restorative material used and remaining dentin thickness (RDT) come into play. The importance of these multiple events varies somewhat from one restoration to another and from one patient to another.¹⁰

Evidence shows that pulpal inflammatory reactions to cavity preparation subside after about 3 weeks of performing IPC and odontoblast activity is established once 28 days have elapsed.^11,12 Clinical and radiographic follow up was done at 1 month in the present study, thus transient inflammatory response to operative procedure was expected to have subsided.

GIC is most commonly used restorative material in paediatric dentistry because of its adhesive properties. Frankenbergeret al reported that Fuji IX sets faster, have good marginal seal and is of higher viscosity because of finer glass particles, anhydrous polyacrylic acids of high molecular weight and a high powder to liquid mixing ratio.¹³ Due to these properties GIC (Fuji IX) was used in the study.

CH inhibits bacterial enzymes by means of hydroxyl ions that act on the cytoplasmic membrane of bacteria, generating the antibacterial effect. It also activates tissue enzymes, such as alkaline phosphatase, leading to its mineralizing effect. Due to its unique mechanism of action calcium hydroxide is considered gold standard for IPC.¹⁴

While CH has been extensively utilized in the past for IPC, use of SDF has been reserved for remineralization of superficial enamel lesions.¹⁵ Llordaet aldocumented its caries preventing efficacy in permanent first molars.¹⁶ Yamagaet alhave reported its use in the treatment and prevention of caries in deciduous teeth. If SDF is applied in the presence of softened dentin, it will arrest the subsequent progress of dental caries.¹⁷ In animal experiment SDF exerted no serious effect histologically on the pulp by application to the medium deep cavity.¹⁸ In application to human deciduous teeth with moderate dentin caries SDF exerted no clinical symptoms.¹⁹

In the present study, SDF is compared with CH for its potential use as IPC agent and no significant difference was found between them. One patient reported with pain of irreversible nature in CH group which was followed by pulpectomy. However, this could be attributed to error in case selection, as clinical findings and histological picture do not always necessarily coincide.

Yamagaet al concluded that SDF enhances the bond strength of GIC to bovine dentin.²⁰ But, in the present study 5 teeth were reported with dislodged restoration. This could be attributed to poor anatomical form and marginal integrity of conventional GICs. However, all were asymptomatic and re-restoration was done.²¹ Another factor that plays role in the success of IPC is the location of tooth in the arch. In the present study, first primary molar failed as compared to second primary molars. This result was very similar to those reported by Sveenet al and Al Zayer M et al.^22,23

Gupta  et al and Sinha Net al mentioned that SDF has remineralizing, re-hardening and antimicrobial efficacy and hence can act as effective IPC materials.^24,25 Korwaret al also recommended SDF as IPC material for management of deep caries.¹⁰ But the disadvantage of using SDF is the black staining effect on carious tissue. This discoloration is caused by the oxidation of ionized silver into metallic silver.⁶

Conclusion

The present study highlights that both SDF and CH were equally suitable for IPC in primary teeth, following clinical and radiographic criteria. The success rate with SDF was found to be 100% and with CH, it was 93.75% with no significant difference between them. Results of the present study indicated that SDF can be used as potential substitute to CH for IPC in primary teeth. Further, studies with larger sample size and long term follow up are required to validate the results and to recommend SDF as standard indirect pulp capping material.