Thiago Henrique Scarabello Stape1, Arzu Tezvergil-Mutluay2, Mustafa Murat Mutluay3, Luís Roberto Marcondes Martins4, Rosana Leal do Prado5, Eliane Cristina Gava Pizi6, Leo Tjäderhane7. 1. Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Lemminkaisenkatu 2, 20520 Turku, Finland; Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Av. Limeira Piracicaba, SP 13414-903, Brazil; Dental School of Presidente Prudente, University of Western São Paulo, Rua José Bongiovani, 700 - Cidade, Presidente Prudente, 19050-920 SP, Brazil. Electronic address: thiagohs@hotmail.com. 2. Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Lemminkaisenkatu 2, 20520 Turku, Finland; Department of Restorative Dentistry and Cariology, Department of Prosthetic Dentistry, Institute of Dentistry, University of Turku, Turku, Finland. Electronic address: arztez@utu.fi. 3. Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Lemminkaisenkatu 2, 20520 Turku, Finland; Department of Cariology, Institute of Dentistry, University of Turku, Turku, Finland. Electronic address: mmutluay@gmail.com. 4. Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Av. Limeira Piracicaba, SP 13414-903, Brazil. Electronic address: martins@fop.unicamp.br. 5. Dental School of Presidente Prudente, University of Western São Paulo, Rua José Bongiovani, 700 - Cidade, Presidente Prudente, 19050-920 SP, Brazil. Electronic address: rosanahb@yahoo.com.br. 6. Dental School of Presidente Prudente, University of Western São Paulo, Rua José Bongiovani, 700 - Cidade, Presidente Prudente, 19050-920 SP, Brazil. Electronic address: elianepizi@unoeste.br. 7. Department of Oral and Maxillofacial Diseases, University of Helsinki, Helsinki, Finland; Helsinki University Hospital, Helsinki, Finland; Research Unit of Oral Health Sciences, and Medical Research Center Oulu (MRC Oulu), Oulu University Hospital and University of Oulu, Oulu, Finland. Electronic address: leo.tjaderhane@helsinki.fi.
Abstract
OBJECTIVE: To examine the feasibility of dimethyl sulfoxide (DMSO) incorporation into relatively hydrophilic resins as a new potential method to improve the durability of resin-dentin bonds. METHODS: Six experimental light-curing BisGMA/HEMA resins solvated in ethanol and DMSO with increasing concentrations of DMSO (0, 0.5, 1, 2, 4 and 10wt%) were prepared. The degree of conversion (DC) was evaluated by Fourier Transform Infrared Spectroscopy (n=8); water sorption (Wsp) and water solubility (Wso) were gravimetrically assessed (n=10); and flexural strength (FS) and elastic modulus (E) were determined by a three-point bending flexural test (n=10). Flat dentin surfaces on sound third molars (n=10/group) were bonded with resins containing 0, 2, 4 and 10wt% DMSO used as a two-step etch-and-rinse system. Dentin microtensile bond strength was determined at 24h and after two-year aging in artificial saliva at 37°C. RESULTS: DMSO significantly affected Wsp (p=0.0006), DC, Wso, FS, and E (p<0.0001). In general, the resins' mechanical/physical properties were not affected by 2% or lower DMSO incorporation. Incorporation of 4% or higher DMSO content significantly increased DC, Wsp and Wso, but 2% or higher DMSO concentrations significantly reduced FS and E. No influence on immediate dentin bond strength occurred up to 4% DMSO incorporation. While 4% or higher DMSO concentrations impaired bond strength over time, the resin containing 2% DMSO presented significant higher dentin bond strength compared to the control resin after two year-aging. SIGNIFICANCE: The use of DMSO as a new solvent in adhesive dentistry improves dentin bonding of relatively hydrophilic resins over time. 2% DMSO incorporation in BisGMA/HEMA resins should be sufficient to reduce bond strength loss without compromising polymer mechanical strength and physical properties.
OBJECTIVE: To examine the feasibility of dimethyl sulfoxide (DMSO) incorporation into relatively hydrophilic resins as a new potential method to improve the durability of resin-dentin bonds. METHODS: Six experimental light-curing BisGMA/HEMA resins solvated in ethanol and DMSO with increasing concentrations of DMSO (0, 0.5, 1, 2, 4 and 10wt%) were prepared. The degree of conversion (DC) was evaluated by Fourier Transform Infrared Spectroscopy (n=8); water sorption (Wsp) and water solubility (Wso) were gravimetrically assessed (n=10); and flexural strength (FS) and elastic modulus (E) were determined by a three-point bending flexural test (n=10). Flat dentin surfaces on sound third molars (n=10/group) were bonded with resins containing 0, 2, 4 and 10wt% DMSO used as a two-step etch-and-rinse system. Dentin microtensile bond strength was determined at 24h and after two-year aging in artificial saliva at 37°C. RESULTS:DMSO significantly affected Wsp (p=0.0006), DC, Wso, FS, and E (p<0.0001). In general, the resins' mechanical/physical properties were not affected by 2% or lower DMSO incorporation. Incorporation of 4% or higher DMSO content significantly increased DC, Wsp and Wso, but 2% or higher DMSO concentrations significantly reduced FS and E. No influence on immediate dentin bond strength occurred up to 4% DMSO incorporation. While 4% or higher DMSO concentrations impaired bond strength over time, the resin containing 2% DMSO presented significant higher dentin bond strength compared to the control resin after two year-aging. SIGNIFICANCE: The use of DMSO as a new solvent in adhesive dentistry improves dentin bonding of relatively hydrophilic resins over time. 2% DMSO incorporation in BisGMA/HEMA resins should be sufficient to reduce bond strength loss without compromising polymer mechanical strength and physical properties.