D M De-Paula1, D Lomonaco2, A M P Ponte3, K E Cordeiro3, M M Moreira1, S E Mazzetto4, V P Feitosa5. 1. Postgraduate Program in Dentistry, Federal University of Ceará, Fortaleza, Brazil; Paulo Picanço School of Dentistry, Fortaleza, Brazil. 2. Postgraduate Program in Dentistry, Federal University of Ceará, Fortaleza, Brazil; Department of Organic and Inorganic Chemistry, Federal University of Ceará, Fortaleza, Brazil. 3. Paulo Picanço School of Dentistry, Fortaleza, Brazil. 4. Department of Organic and Inorganic Chemistry, Federal University of Ceará, Fortaleza, Brazil. 5. Paulo Picanço School of Dentistry, Fortaleza, Brazil. Electronic address: victor.feitosa@facpp.edu.br.
Abstract
OBJECTIVE: To investigate the effects of natural collagen cross-linkers incorporation in phosphoric acid etchant on dentin biomodification, microtensile bond strength (μTBS) and nanoleakage (NL) of a two-step etch-and-rinse adhesive. METHODS: Experimental aqueous solution of 37% ortho-phosphoric acid were prepared with the addition of 2% biomodification agents: Lignin (LIG) from industrial paper production residue, Cardanol (CARD) from cashew-nut shell liquid, and Proanthocyanidin (PAC) from grape-seed extract. Negative control (NC) was acid solution without cross-linker whilst commercial control (CC) was Condac 37 gel (FGM). Dentin specimens were assayed by FTIR after 15s etching to detect collagen cross-linking. Extracted third molars were used for μTBS (n=7) and fracture mode analysis of Optibond S (Kerr), tested after 24h or 1000 thermal cycles. NL was surveyed by SEM. Statistical analysis was performed with two-way ANOVA and Tukey's test (p<0.05). RESULTS: FTIR confirmed cross-linking for all agents. μTBS of CC was the highest (46.6±6.2MPa), but reduced significantly after aging (35.7±5.2MPa) (p<0.001). LIG (30.6±3.7MPa) and CARD (28.3±1.8MPa) attained similar μTBS which were stable after aging (p>0.05). Fracture mode was predominantly adhesive. At 24h, all groups showed presence of silver uptake in hybrid layer, except CARD. After aging, CARD- and LIG-treated specimens exhibited little amount of silver penetration. CC, PAC and NC showed gaps, great nanoleakage at hybrid layer and presence of water channels in adhesive layer. SIGNIFICANCE: Altogether, ortho-phosphoric acid incorporated with LIG and CARD promotes stable resin-dentin bond strength with minor nanoleakage after aging, thereby achieving therapeutic impact without additional clinical steps.
OBJECTIVE: To investigate the effects of natural collagen cross-linkers incorporation in phosphoric acid etchant on dentin biomodification, microtensile bond strength (μTBS) and nanoleakage (NL) of a two-step etch-and-rinse adhesive. METHODS: Experimental aqueous solution of 37% ortho-phosphoric acid were prepared with the addition of 2% biomodification agents: Lignin (LIG) from industrial paper production residue, Cardanol (CARD) from cashew-nut shell liquid, and Proanthocyanidin (PAC) from grape-seed extract. Negative control (NC) was acid solution without cross-linker whilst commercial control (CC) was Condac 37 gel (FGM). Dentin specimens were assayed by FTIR after 15s etching to detect collagen cross-linking. Extracted third molars were used for μTBS (n=7) and fracture mode analysis of Optibond S (Kerr), tested after 24h or 1000 thermal cycles. NL was surveyed by SEM. Statistical analysis was performed with two-way ANOVA and Tukey's test (p<0.05). RESULTS: FTIR confirmed cross-linking for all agents. μTBS of CC was the highest (46.6±6.2MPa), but reduced significantly after aging (35.7±5.2MPa) (p<0.001). LIG (30.6±3.7MPa) and CARD (28.3±1.8MPa) attained similar μTBS which were stable after aging (p>0.05). Fracture mode was predominantly adhesive. At 24h, all groups showed presence of silver uptake in hybrid layer, except CARD. After aging, CARD- and LIG-treated specimens exhibited little amount of silver penetration. CC, PAC and NC showed gaps, great nanoleakage at hybrid layer and presence of water channels in adhesive layer. SIGNIFICANCE: Altogether, ortho-phosphoric acid incorporated with LIG and CARD promotes stable resin-dentin bond strength with minor nanoleakage after aging, thereby achieving therapeutic impact without additional clinical steps.