OBJECTIVETo study the types of matrix metalloproteinases (MMPs) involved in dentin bonding interface degradation.

METHODSDentin slices were prepared and treated with two adhesive systems (Single Bond 2 or Clearfil S3 Bond). The dentin surface was bonded with composite resin. All specimens were immersed in sterile artificial saliva for 0 or 6 months, and their micro-shear bond strength (muSBS) were measured. The fracture modes were observed through field emission scanning electron microscope (FE-SEM). Dentin slices with 4 mm x 3 mm x 1 mm dimensions were prepared. The slices were divided into three groups according to the treatment modes (negative control, Single Bond 2, and Clearfil S3 Bond). All specimens were stored in sterile artificial saliva for 0 or 6 months. The concentrations of MMP-1, -2, -3, -8, and -9 of each group were detected through fluorescent microsphere immunoassay.

RESULTSThe muSBS of both adhesive systems significantly decreased after storage aging. Significant differences in failure modes within the four groups tested in this study were observed. Compared with the negative control, the concentrations of MMP-1 and MMP-3 in different adhesive groups showed no significant difference after storage aging. However, the concentrations of MMP-2, -8, and -9 in Single Bond 2 group and the concentrations of MMP-8 and -9 in Clearfil S3 Bond group significantly decreased after 6 months of storage aging.

CONCLUSIONSignificant degradation occur in the dentin bonding interface of both adhesive groups under 6 months aging challenge. The concentrations ofdentinal MMP-2, -8, and -9 significantly decrease after treatment with adhesives and aging, indicating that these MMPs have an important function in dentin bonding interface degradation.