Effect of a self-assembling peptide (P₁₁-4) and dentin matrix protein 1 (DMP-1) on the bond strength of resin...

This study evaluated whether Dentin Matrix Protein 1 (DMP-1) enhances the effect of P₁₁-4, a synthetic self-assembling peptide, on the microtensile bond strength (µTBS) of caries-affected dentin (CAD). Coronal dentin slices (∼4 mm) from 48 extracted human third molars were allocated to six groups (n = 8): sound dentin (C+), untreated CAD (C-), and CAD treated with DMP-1 (1 µg/mL), P₁₁-4 (1 µg/mL), P₁₁-4 (1 mg/mL), or DMP-1 (1 µg/mL) plus P₁₁-4 (0.5 µg/mL). CAD was generated with a Streptococcus mutans (UA159) biofilm model and selective caries removal to a leathery endpoint. Treatments were applied for 5 min (50 µL), followed by 1 min of a supersaturated calcium-phosphate solution. An etch-and-rinse adhesive (Adper Single Bond 2) and resin composite were placed, and specimens were stored in simulated body fluid for 24 h under simulated pulpal pressure at 37 °C. Beams (∼1 mm²) were tested in tension (tooth as experimental unit). P₁₁-4 1 mg/mL showed the highest µTBS among CAD groups (33.1 ± 4.7 MPa), followed by DMP-1/P₁₁-4 (19.9 ± 5.8 MPa) and P₁₁-4 1 µg/mL (17.3 ± 3.2 MPa). DMP-1 alone (12.2 ± 3.6 MPa) and P₁₁-4 1 µg/mL did not differ from untreated CAD (12.1 ± 7.3 MPa); sound dentin was highest overall (57.2 ± 12.9 MPa). Biomimetic pretreatment reduced premature failures and increased mixed failures, but no strategy restored bonding to sound-dentin levels at 24 h. Within these limits, higher P₁₁-4 concentration produced the greatest immediate CAD bond strength, whereas adding DMP-1 to low-dose P₁₁-4 did not significantly enhance bonding beyond P₁₁-4 alone. CLINICAL SIGNIFICANCE: Caries-affected dentin is a challenging substrate for adhesive restorations because of its reduced mineral content and compromised mechanical properties. Among the biomimetic pretreatments tested, P₁₁-4 at 1 mg/mL produced the greatest increase in immediate microtensile bond strength to caries-affected dentin, and the combined DMP-1/ P₁₁-4 pretreatment also achieved significantly higher bond strength than untreated dentin, although it did not exceed P₁₁-4 applied alone. Pretreatment with the self-assembling peptide P₁₁-4 may therefore serve as an adjunct to adhesive protocols in minimally invasive caries management, recognizing that no treatment restored bonding to sound-dentin levels and that only immediate strength was assessed.