Lucas Bonfanti Silvestrin1, Isadora Martini Garcia1, Fernanda Visioli2, Fabrício Mezzomo Collares1, Vicente Castelo Branco Leitune3. 1. Department of Dental Materials, School of Dentistry, Federal University of Rio Grande do Sul, Ramiro Barcelos Street, 2492, Rio Branco, Porto Alegre, RS, 90035-003, Brazil. 2. Oral Pathology Departament, School of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492, Rio Branco, Porto Alegre, RS, 90035-003, Brazil. 3. Department of Dental Materials, School of Dentistry, Federal University of Rio Grande do Sul, Ramiro Barcelos Street, 2492, Rio Branco, Porto Alegre, RS, 90035-003, Brazil. vicente.leitune@ufrgs.br.
Abstract
OBJECTIVES: The objective of this study is to formulate experimental dental adhesives with different polyhexamethylene guanidine hydrochloride concentrations (PHMGH) and evaluate their physical, chemical, and biological properties. MATERIALS AND METHODS: The experimental adhesives were formulated with 0 (control, GCTRL), 0.5 (G0.5%), 1 (G1%), or 2 (G2%) wt.% into the adhesive. The adhesives were analyzed for degree of conversion (DC%), softening in solvent (ΔKHN%), ultimate tensile strength (UTS), microtensile bond strength (μTBS) immediately and after 1 year of aging, antibacterial activity, and cytotoxicity. RESULTS: There were no differences among groups for DC%, ΔKHN%, and UTS (p > 0.05%). There were no differences between each PHMGH-doped adhesive compared to GCTRL in the immediate μ-TBS (p > 0.05). Adhesives with at least 1 wt.% of PHMGH presented better stability of μ-TBS. PHMGH-doped adhesives showed improved longitudinal μ-TBS compared to GCTRL (p < 0.05). Lower Streptococcus mutans biofilm formation was observed for PHMGH-doped adhesives (p < 0.05). There was lower viability of planktonic S. mutans in the media in contact with the samples when at least 1 wt.% of PHGMGH was incorporated (p < 0.05). The formulated adhesives showed no cytotoxicity against pulp cells (p > 0.05). CONCLUSIONS: The adhesive with 2 wt.% of PHMGH showed the highest antibacterial activity, without affecting the physicochemical properties and cytotoxicity, besides conferring stability for the dental adhesion. CLINICAL RELEVANCE: PHMGH, a positively charged polymer, conveyed antibacterial activity to dental adhesives. Furthermore, it did not negatively affect the essential physicochemical and biocompatibility properties of the adhesives. More importantly, the incorporation of PHMGH provided stability for the μ-TBS compared to the control group without this additive.
OBJECTIVES: The objective of this study is to formulate experimental dental adhesives with different polyhexamethylene guanidine hydrochloride concentrations (PHMGH) and evaluate their physical, chemical, and biological properties. MATERIALS AND METHODS: The experimental adhesives were formulated with 0 (control, GCTRL), 0.5 (G0.5%), 1 (G1%), or 2 (G2%) wt.% into the adhesive. The adhesives were analyzed for degree of conversion (DC%), softening in solvent (ΔKHN%), ultimate tensile strength (UTS), microtensile bond strength (μTBS) immediately and after 1 year of aging, antibacterial activity, and cytotoxicity. RESULTS: There were no differences among groups for DC%, ΔKHN%, and UTS (p > 0.05%). There were no differences between each PHMGH-doped adhesive compared to GCTRL in the immediate μ-TBS (p > 0.05). Adhesives with at least 1 wt.% of PHMGH presented better stability of μ-TBS. PHMGH-doped adhesives showed improved longitudinal μ-TBS compared to GCTRL (p < 0.05). Lower Streptococcus mutans biofilm formation was observed for PHMGH-doped adhesives (p < 0.05). There was lower viability of planktonic S. mutans in the media in contact with the samples when at least 1 wt.% of PHGMGH was incorporated (p < 0.05). The formulated adhesives showed no cytotoxicity against pulp cells (p > 0.05). CONCLUSIONS: The adhesive with 2 wt.% of PHMGH showed the highest antibacterial activity, without affecting the physicochemical properties and cytotoxicity, besides conferring stability for the dental adhesion. CLINICAL RELEVANCE: PHMGH, a positively charged polymer, conveyed antibacterial activity to dental adhesives. Furthermore, it did not negatively affect the essential physicochemical and biocompatibility properties of the adhesives. More importantly, the incorporation of PHMGH provided stability for the μ-TBS compared to the control group without this additive.
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