MMP Inhibitors and Dentin Bonding: Systematic Review and Meta-Analysis

Abstract

Objectives: Resin-dentin bond strength decreases over time. This reduction is related to the loss of hybrid layer integrity. Collagenolytic enzymes, especially matrix metalloproteinases (MMPs), are responsible for the degradation of the collagen matrix of the hybrid layer. Various MMP inhibitors with the ability to prevent enzymatic degradation have been identified. This study aimed to systematically review the literature for studies which evaluated the effect of MMP inhibitors on the immediate and aged dentin bond strengths. Study SelectionScreening and analysis were carried out by two reviewers. Two databases were searched, and from a total of 740 articles, 43 were accepted for full review. 21 articles with 0.2%-2% chlorhexidine (CHX) treatments were included for meta-analysis. A risk of bias assessment was performed on all studies chosen for meta-analysis. A variety of MMP inhibitors have been studied, CHX being the most widely used.

Conclusions: A clear trend for a lower loss of dentin bond strength was observed with different MMP inhibitors. In meta-analysis, no significant difference was seen between the CHX and control in the immediate bond strengths. Bond strengths in the CHX group were significantly higher than the control group after aging (P < 0.001). The percentage of fractures occurring at the adhesive interface increased after aging. Five out of 21 studies included in the meta-analysis had high and the rest medium risk of bias. More long-term studies with lower risks of bias should be carried out to increase the reliability of results. Clinical RelevanceThe use of MMP inhibition with chlorhexidine can be recommended to increase the longevity of resin-dentin bond strength.

Figure 1

Protocol for the systematic literature review.

Figure 2

Forest plot of studies at baseline. The N for both groups was 396 samples. The total random effect standardized mean difference (SMD) was −0.0821 (CI 95% −0.240; 0.076). The difference was not statistically significant (t = −1.019, P=0.308). The I² (inconsistency) was 21.68%.

Figure 3

Forest plots of studies after 6, 12, and 24 months of aging. (a) Chlorhexidine (CHX) vs. control at six months. The N for both groups was 339 samples. The total random effect SMD was 0.907 (CI 95% 0.517; 1.297). The difference was statistically significant (t = 4.568, P < 0.001). The I² was 82.11%. (b) CHX vs. control after 12 month aging. The N for both groups was 173 samples. The total random effect SMD was 0.821 (CI 95% 0.367; 1.275). The difference was statistically significant (t = 3.557, P < 0.001). The I² was 74.97%. (c) CHX vs. control after 24-month aging. The N for both groups was 40 samples. The total random effect SMD was 2.168 (CI 95% 1.627; 2.708). The difference was statistically significant (t = 7.982, P < 0.001). The I² was 0.00%.