Direct-pulp-capping Effect with Synthetic-peptide-derivatives of Dentin-matrix-protein1

Objectives: The purpose of this study was to examine, histopathologically and immunohistochemically, the effects of various experimentally developed adhesive resin systems containing synthetic peptide derivatives (pA, pB) of dentin matrix protein 1 (DMP1) on the wound healing process of exposed rat pulp.

Methods:The four experimental groups were capped with a combination of the following primers and bonding agents: commercially available Mega bond^® primer (Kuraray, MBP) 1 drop (30mg), CaCl₂ (3.0mg) and synthetic peptide derivatives (pA:1.2mg, pB:1.8mg) of DMP1; and commercially available Mega bond^® bonding agent (MBB), and experimental MBB containing 10wt% hydroxyapatite (MB2). The two control groups were capped with MBP and MB2 (CONT1) and with Dycal^® (Dentsply Sankin) and MBB (CONT2). The rats were sacrificed on the 14th post-operative day. The sample number of each group was 5. The specimens were alternately stained with H-E, Hucker-Conn bacterial stain, Reticulin silver impregnation and sABC method on TGF b1 and DMP1. The following parameters were microscopically evaluated: pulp tissue disorganization (PTD), inflammatory cell inflammation (ICI), reparative dentin formation (RDF), and bacterial penetration (BP). The findings were graded using four legend scales. Each result was statically analyzed using the Kruskal-Wallis H-test and then Mann-Whitney U-test as a post-hock test (p<0.05).

Results: Especially in group1, an extremely strong leading effect and three distinctive layers of RDF were clearly observed. In group2, two distinctive layers of RDF were recognized and formed at a relatively more outer area than in group1. But in group3, RDF was located at a shallower area of the pulp and a distinctive layer structure was not noticeable. Concerning DMP1 staining, groups1 and 4 showed relatively stronger reaction findings than groups 2 and 3.

Conclusions: To summarize the results, the experimental adhesive resin system of group1 was the most effective system in initiating an early repair process after direct-pulp-capping.