Comparison of efficacy of natural antioxidants on the adhesive bond strength of NaOCL treated dentin

Introduction

A successful composite restoration depends on the adhesive composite forming a strong, durable bond between the composite and the dentin. However, the use of sodium hypochlorite for biomechanical preparation of root canals changes the structure of dentin surface and partially removes collagen fibrils, affecting the interaction with adhesive restorative materials. Many studies demonstrated that NaOCl reduces bond strength between composites and dentin.1, 2, 3 The compromised bond strength to NaOCl treated dentin could be restored by the application of an antioxidant agent before the adhesive procedure. Sodium ascorbate is the most studied antioxidant agent. 4, 5 But, Erhardt et al showed that sodium ascorbate may either compromise or enhance the degradation of composite dentin bonds over time, depending on the adhesive used.4 So, there is an increased interest in evaluating new substances to neutralize effects of oxidative compounds.

Aim

To Compare and evaluate the effect of Grape seed Extract, Propolis and Vitamin E on the Bond strength of NaOCl treated dentin

Materials and Methods

Non carious human mandibular first molars collected

Figure 1

Specimen: Human molars

Exclusion criteria

Teeth with Caries, Fractures, Craze lines, Development defects

Preparaton of 5% propolis

5g propolis powder + 100mL of distilled water

Figure 2

Preparation of 5% propolis

Preparaton of 5% grape seed solution (OPC’s)

5g of Grape Seed extract (powder) + 100mL distilled water

Figure 3

Preparationof 5% grape seed solution

Occlusal surfaces of the teeth were flattened, which eliminates the pits and grooves. Standardized class I cavities were prepared on occlusal surfaces of tooth with following dimensions.

1. 4mm-wide (bucco-lingual))

2. 4mm-deep (occluso-gingival)

3. 4mm-long (mesio-distal)

Using ISO size (NO.001) round bur and ISO size (NO.112) straight fissure, under copious water coolant in a high speed hand piece.

Figure 4

Measurement of the specimen using Digital calipers

Teeth were randomly divided into five groups of 10 teeth each depending on the agent used.

1. Group I - Negative control group

2. Group II - Positive control group

3. Group III – Propolis

4. Group IV - Grape seed Extract

5. Group V – Vitamin E

After surface treatment of teeth in each group with different agents, adhesive system (Fusion bond 7) was applied to the surface of the cavities, as per the manufacturer’s instructions. After bonding procedure, all teeth received a Nanohybrid composite restoration (Ivoclar) in increments. Each increment was light cured for 40 seconds using a light curing unit set at 1200mW/cm2.

Figure 5

Placement of adhesive restoration and curing

To perform the bondstrength test, specimens were sectioned through centre of the restoration (both buccoingually and mesiodistally) with a water cooled slow speed diamond disc that resulted in four resin-dentin specimens from each tooth.

Figure 6

Sectioned specimens

All the specimens were mounted in acrylic tube or mold (20 mm height &10 mm diameter) with an auto-cure acrylic resin. The root was positioned at the centre of the acrylic tube vertically; with only crown portion exposed and allow the acrylic to set completely before doing the test.

Results

One way ANOVA test was done for statistical analysis

Graph 1

Bond strengths of different groups

The data were tabulated and statistically analysed using analysis of variance (ANOVA) test to compare the SBS between five groups. The selected level of variance was 0.05. ANOVA showed a significant difference in mean SBSs at P < 0.05. The mean SBS of all five groups was highest in Group III and was least in Group II

Discussion

In this study, the effects of Propolis, grape seed extract, Vitamin E on bond strength of self-etch adhesive to dentin are evaluated. The use of NaOCl for root canal preparation may negatively affect bond strength of post endodontic restoration of composite to dentin.1 The current study found a reversal effect on bonding comprimised by NaOCl treatment by Antioxidants. Antioxidants can act in three different ways. 6

Propolis, Also called as the Bee Glue, derived from the salivary secretion of the Honey Bees. It has Free radical scavenging ability, Anti-viral, anti-bacterial & anti-fungal agent, Anti-inflammatory action.4, 6, 3 Proanthocyanidins, extracted from Grape seed are known to increase dentin matrix mechanical properties, decrease extracellular degradation by inhibhiting proteases and also have antioxidant and antibacterial properties.2 Vitamin E is proven to have antioxidant property. 7

Conclusion

Grape Seed Extract, Propolis and Vitamin E increased shear bond strength of the composite restoration to NaOCl treated dentin. Treatment with antioxidants gave bond strength superior to that of untreated dentin. They allow free radical polymerization of adhesive resin without its premature termination.

Conflict of Interest

The authors declare that there is no conflict of interest.

Source of Funding

None.