Objectives: Chlorhexidine (CHX), a commonly used antibacterial agent in dentistry is known to have an inhibitory effect on matrix metalloproteinases (MMPs). There are indications that inhibition of endogenous MMPs could lead to the preservation of hybrid layer. The current study evaluated the effect of 0.5% and 2.0% CHX in resin-dentin bond strength (BS) over a six-month period.
Methods: The occlusal surfaces of forty-eight caries-free extracted molars were removed to expose a dentin surface. Each tooth was sectioned into halves and randomly divided into 12 groups (N=8). The dentin surface was etched with Ultra-Etch (Ultradent) and dried with oil-free air. The surface was rehydrated with water, 0.5% CHX or 2.0% CHX before application of adhesive Peak LC (Ultradent) and composite (Filtek Supreme Plus, 3M ESPE) buttons. Shear bond strengths were recorded at a uniform crosshead speed of 5mm/min immediately, at 1 month, 3 month and 6 month after aging in 37°C water.
Results: Six-month storage in water resulted in significant BS reduction in all groups (p=0.005). Both 0.5% and 2.0% CHX treated samples showed less reduction in BS over a six-month period. However, only 0.5% CHX group (p=0.004) was statistically different from the control group.
Table 1. Mean Bond Strength ± Standard Deviation (MPa)
| Control | 2.0% CHX | 0.5% CHX |
Immediate Loading | 13.07 (±5.0) | 15.16 (±5.5) | 15.94 (±7.2) |
1-month aging | 10.92 (±8.4) | 12.31 (±7.4) | 14.94 (±10.7) |
3-month aging | 9.34 (±3.2) | 11.62 (±3.7) | 13.90 (±3.2) |
6-month aging | 5.33 (±2.7) | 9.54 (±2.5) | 12.47 (±3.9) |
Conclusions: The use of 0.5% CHX solution has shown a statistically significant effect on preservation of dentin bond strength over a six-month period.