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Title: 0224 - Adhesion and Remineralization Potential of Proteoglycan-infused Dentin

Authors:

Ricardo Noschang, Federal University of Santa Catarina
Daniel Seebold, University of North Carolina
Islam Abd Alraheam, University of North Carolina
Rick Walter, University of North Carolina
Patricia Miguez (Presenter)
University of North Carolina

Abstract:

Objectives: Proteoglycans (PGs) play a role in keeping the dentin organic matrix hydrated, which is important for adhesive penetration. This study tested the effects of the addition of small leucine-rich proteoglycan (SLRP) proteins on phosphori acid (PA)-treated dentin in microtensile bond strength (MTBS); and investigated the role of such SLRPs in the remineralization potential of PA-demineralized dentin collagen.

Methods: Fifty human molars were used to obtain coronal dentin sections (n=500). SLRPs were either decorin (DE) or biglycan (BI) in their core or proteoglycan form (with glycosaminoglycans, GAGs). Samples were assigned into five groups: 1. no treatment (no-tx), 2. DE core, 3. DE+GAGs, 4. BI core, 5.BI+GAGs. All samples were etched with PA for 15s, rinsed, and treated according to each group prior to application of Adper Single Bond Plus and a composite build-up. Twenty-four hours after the procedure, samples were tested for MTBS. Analysis of the fractured beams were done under Field-emission Scanning Electron Microscopy (FE-SEM). Additional two molars were used to obtain dentin blocks that were fully demineralized with PA, infused with the DE core or left untreated (no-tx), and placed in a remineralization solution for 2 weeks. Remineralization patterns were evaluated using Transmission Electron Microscopy (TEM).

Results: The MTBS test presented a mean MTBS of 53.2 ±15.6 MPa in the no-tx group with no statistical significant difference to DE core (48.4±13.7 MPa) and BI core (47.1±15.4 MPa). The GAGs groups DE+GAGs (27.0±13.7) and BI+GAGs (37.2±19.4) showed decreased MTBS compared to no-tx (p<0.001). All no-tx samples had adhesive failures. A low number (<10%) of cohesive failures in dentin was noticed for the other groups. TEM images indicate a better remineralization pattern of DE-core compared to no-tx, presenting more intact fibril characteristics.

Conclusions: The results suggest that the core proteins decorin and biglycan seem not to affect dentin bonding but the presence of GAGs is detrimental to immediate bond strength. Aging of samples will determine how their presence affects long-term adhesion. Decorin core protein presence appears to favor the remineralization process and fibril stability in a qualitative analysis.

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE

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