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Low-temperature flow-synthesis-assisted urethane-grafted zinc oxide-based dental composites: physical, mechanical, and antibacterial responses.
Bukhari, JH, Khan, AS, Ijaz, K, Zahid, S, Chaudhry, AA, Kaleem, M
Journal of materials science. Materials in medicine. 2021;(8):87
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Abstract
A novel way was adopted to graft zinc oxide (ZnO) with urethane-modified dimethacrylate (UDMA) in order to utilize them as reinforcing agents in resin-based dental composites. Experimental novel composites were synthesized having UDMA-grafted and nongrafted ZnO, at a concentration of 0 wt.%, 5 wt.%, and 10 wt.%. The same concentrations of ZnO were also incorporated in Filtek Z250 XT (3 M ESPE, USA). The antibacterial behavior was evaluated against Streptococcus mutans by direct-contact test at one, three, and seven days of incubation. The compressive strength and Vickers microhardness were tested as per ISO 9917 and ISO/CD6507-1, respectively. For abrasive wear resistance, mass loss and roughness average after tooth-brushing cycles of 24,000 at custom-made tooth-brushing simulator were evaluated using noncontact profilometer. Data analysis was carried out using post hoc Tucky's test and nonparametric Kruskal-Wallis test. Direct contact test revealed that the antibacterial potential of novel and commercial composites was increased with an increase in the concentration of grafted ZnO as compared with nongrafted, whereby the potential was the highest at day seven. There was a significant decrease in compressive strength and Vickers hardness of commercial composites on addition of grafted ZnO while there was no significant difference in the strength of experimental novel composite. The abrasive wear of commercial and experimental composites was within clinical limits. Low-temperature flow-synthesis method was successfully employed to synthesize grafted and nongrafted ZnO. The UDMA-grafted ZnO can be incorporated into dental composites without decreasing their strength and these composites can be used to combat secondary caries.
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Effect of Cavity Disinfectants on Dentin Bond Strength and Clinical Success of Composite Restorations-A Systematic Review of In Vitro, In Situ and Clinical Studies.
Coelho, A, Amaro, I, Rascão, B, Marcelino, I, Paula, A, Saraiva, J, Spagnuolo, G, Marques Ferreira, M, Miguel Marto, C, Carrilho, E
International journal of molecular sciences. 2020;(1)
Abstract
Cavity disinfection becomes an important step before a dental restorative procedure. The disinfection can be obtained cleaning the dental cavity with antimicrobial agents before the use of adhesive systems. The aim of this study was to conduct a systematic review on the effect of different cavity disinfectants on restorations' adhesion and clinical success. A search was carried out through the Cochrane Library, PubMed, and Web of Science. In vitro and in situ studies reporting results on dentin bond strength tests, and clinical studies published until August 2020, in English, Spanish and Portuguese were included. The methodological quality assessment of the clinical studies was carried out using the Revised Cochrane risk-of-bias tool. Chlorhexidine could preserve adhesion to dentin. EDTA and ethanol had positive results that should be further confirmed. Given the significant lack of scientific evidence, the use of lasers, fluoridated agents, sodium hypochlorite, or other products as cavity disinfectants should be avoided. Chlorhexidine is a safe option for cavity disinfection with adequate preservation of adhesion to dentin. Moreover, future researches should be focused on the efficacy of these disinfectants against cariogenic bacteria and their best application methods.
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Preparation of low shrinkage stress dental composite with synthesized dimethacrylate oligomers.
Luo, S, Liu, F, He, J
Journal of the mechanical behavior of biomedical materials. 2019;:222-228
Abstract
Two dimethacrylate oligomers named polypropylenglycol bis(2-hydroxy-3-methoxypropyl) dimethacrylates (380PPMA and 640PPMA) with different molecular weight were synthesized through ring opening addition reaction between epoxy terminated oligomers PPDE and methacrylic acid, and their structures were confirmed by FT-IR and 1H-NMR spectra. The PPMAs were used to replace TEGDMA partially in Bis-GMA/TEGDMA (50/50, wt./wt.) with the aim to reducing volumetric shrinkage and shrinkage stress of dental resin composites. Dental resin composite without PPMAs was used as control. Double bond conversion (DC), volumetric shrinkage (VS), shrinkage stress, water sorption (WS) and solubility (SL), flexural strength (FS) and modulus (FM) of experimental dental resin composites were investigated. Dynamic mechanical analysis (DMA) was used to evaluate the glass transition temperature (Tg), heterogeneity, and crosslink density (υ). The results showed that dental resin composites contained 640PPMA had slower polymerization rate. Only dental resin composites with 20 wt% of 640PPMA in resin matrix had lower VS than control group (p < 0.05). All of PPMAs containing composites had lower shrinkage stress than control group (p < 0.05). Before water immersion, all of experimental dental resin composites had the same FS and FM (p > 0.05), while after water immersion, FM of dental resin composites with PPMAs became lower than control (p < 0.05). Higher WS and SL were observed in composites with 640PPMA (p < 0.05). Incorporation of PPMAs into dental resin composites could decrease Tg and crosslink density (p < 0.05), but more homogeneous materials could be obtained (p < 0.05). Therefore, PPMAs could be used to reduce volumetric shrinkage and shrinkage stress of dental resin composites, but further studies concerned biocompatibility and service life should be taken because of the higher WS and SL.
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In vitro remineralization of artificial enamel caries with resin composites containing calcium phosphate particles.
Alania, Y, Natale, LC, Nesadal, D, Vilela, H, Magalhães, AC, Braga, RR
Journal of biomedical materials research. Part B, Applied biomaterials. 2019;(5):1542-1550
Abstract
The aim of the study was to evaluate the effect of experimental composites containing dicalcium phosphate dihydrate (DCPD) on remineralization of enamel lesions. Five resin-based composites containing equal parts (in mols) of bisphenol-A glycidyl dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), and 60 vol % of fillers were manipulated. Filler phase was constituted by silanized barium glass and 0, 10, or 20 vol % of DPCD particles, either functionalized (F) or nonfunctionalized (NF) with TEGDMA. Artificial subsurface lesions were produced in human enamel fragments and divided according to the resin composite applied on the lesion (no DCPD, 20% NF, 20% F, 10% NF, 10% F) plus a group without composite build-up (nontreated, NT). Fragments were exposed to 16 days of pH cycling. Specimens were evaluated using transverse microradiography (TMR). Calcium and phosphate concentrations in pH-cycling solutions were determined by spectrophotometry. TMR and ionic concentrations were analyzed using one-way ANOVA/Tukey and Kruskal-Wallis/Dunn test, respectively (alpha: 0.05). All composite groups showed enamel remineralization (3%-23%). Higher mineral recovery in the middle (7%-11%) and bottom (2%-7%) thirds of the lesion was observed in groups with DCPD-containing composites compared to the "no DCPD" group (middle: 1%, bottom: -3%). Lesion depth was significantly reduced in groups using DCPD-containing composites compared to NT group. No noticeable increase in calcium and phosphate ions was observed in the pH-cycling solutions due to the presence of DCPD in the composites. In conclusion, composites with DCPD fractions as low as 10%, regardless of functionalization, were able to promote mineral recovery and reduce lesion depth of enamel lesions. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1542-1550, 2019.
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Laboratory and clinical evaluation of polymer materials reinforced by fibers used in dentistry.
Brożek, R, Koczorowski, R, Dorocka-Bobkowska, B
European review for medical and pharmacological sciences. 2019;(5):1855-1863
Abstract
OBJECTIVE Fiber-reinforced composites (FRC) because of high strength and a low mass can be widely applied in many fields of dentistry. MATERIALS AND METHODS The types of fibers commonly used in dentistry with the description of physicochemical properties of the reinforcing phase and polymer resin, are specified. The influence of the method of fiber positioning in the sample, their diameter, length and shape of fibers visible in cross-section on the strength of the FRC material, are underlined. The work also paid attention to the volume of the material that occurs as a result of the absorption of water from the oral environment and changes in bonding between matrix and fiber. RESULTS The clinical procedures and a description of failures that may possibly happen in the oral cavity presented in the work, confirm that they allow fabrication of minimally invasive, lightweight, durable and biocompatible materials. At the moment, the only material group that can be used by direct technique to reach high load-bearing capacity restorations is FRC. CONCLUSIONS Long-term treatment effectiveness makes FRCs an alternative to prosthetic restorations whose retention is obtained only as a result of mechanically interlocking to the abutment tooth. The use of FRCs in clinical dentistry is part of value-based medicine.
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Load-bearing capacity of novel resin-based fixed dental prosthesis materials.
Cekic-Nagas, I, Egilmez, F, Ergun, G, Vallittu, PK, Lassila, LVJ
Dental materials journal. 2018;(1):49-58
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Abstract
To evaluate the influence of different materials on the load-bearing-capacity of inlay-retained fixed-dental-prosthesis (FDP). Ten types of FDPs were evaluated (n=7/group): Group PEEK CAD-CAM polyetheretherketone (PEEK-TechnoMed), Group RC, made of discontinuous-fiber-composite (EverX Posterior); Group FRC1, made of discontinuous-fiber-composite (EverX Posterior) with two-bundles of continuous-unidirectional fiber-reinforced-composite (FRC) (Everstick C&B); Group FRC2, made of discontinuous-fiber-composite (EverX Posterior) with two-bundles of continuous-unidirectional-FRC (Everstick C&B) covered by two-pieces of short-unidirectional-FRC (Everstick C&B) placed perpendicular to the main-framework; Group FB, CAD-CAM fiber-block (Fibra-Composite Bio-C); Group PMMA, CAD-CAM polymethyl methacrylate block (Temp basic); Group RP, resin-paste; Group FRP1, made of resin-paste (G-Fix) with two-bundles of continuous-unidirectional-FRC (Everstick C&B); Group FRP2, made of resin-paste (G-Fix) two-bundles of continuous-unidirectional-FRC covered by two-pieces of short unidirectional-FRC placed perpendicular to the main-framework and Group exp-FRC, experimental CAD-CAM FRC. The bridges were statically-loaded until fracture. Fracture modes were visually examined. ANOVA revealed that significant differences were observed between FDP-materials (p<0.05). In addition, fiber addition to the framework significantly affected load-bearing-capacity (p<0.05).
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The effect of endodontic irrigants on the microtensile bond strength of different dentin adhesives.
Dikmen, B, Tarim, B
Nigerian journal of clinical practice. 2018;(3):280-286
Abstract
OBJECTIVES The aim of this study was to determine the influence of irrigants on bond strength of adhesive systems. MATERIALS AND METHODS Superficial dentin surfaces of 60 extracted molars were divided into 15 groups, according to irrigants and adhesives. In the control groups, surfaces were irrigated with distilled water. In experimental groups, sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA) + NaOCl, chlorhexidine (CHX), and NaOCl + sodium ascorbate were used as irrigants. Resin composites were then built up using Single Bond, Clearfil SE Bond, and Xeno 3 as adhesives. The microtensile bond strength of groups was determined. Data were statistically analyzed by two-way analysis of variance (ANOVA), one-way ANOVA, and the Bonferroni test. RESULTS NaOCl reduced bond strength of Single Bond and Clearfil SE Bond (P < 0.01). For all adhesive systems, EDTA + NaOCl-treated groups exhibited lower bond strength than control groups (P < 0.01). CHX decreased bond strength of Single Bond (P < 0.01). Application of sodium ascorbate improved compromised bond strength to NaOCl-treated dentin (P < 0.01). CONCLUSION Different irrigants had several effects on bonding of different adhesives. Sodium ascorbate after NaOCl could restore compromised bond strengths.
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New adhesive system based in metals cross-linking methacrylate.
Rubin Cocco, A, de Oliveira da Rosa, WL, Luque Peralta, S, Timm Maske, T, da Silva, AF, Andrade Hartwig, C, Foster Mesko, M, Piva, E, Guerra Lund, R
Journal of the mechanical behavior of biomedical materials. 2018;:519-526
Abstract
This study evaluated the anti-antibiofilm potential of silver methacrylate (Ag) or di-n-butyldimethacrylatetin (Sn) in experimental adhesive systems. Ag and Sn methacrylates were incorporated at 0.5mol%, 1mol% and 2mol% in an adhesive resin. The anti-antibiofilm potential, degree of conversion (DC), microtensile bond strength (μTBS), water sorption/solubility (WSR/SL), bonded interfaces pattern (SEM), cytotoxicity and leaching of Ag and Sn ions were evaluated. Data were statistically analyzed considering α = 0.05. Only Ag at 2% affected DC and μTBS. Ag at 1% and 2% and Sn at 1% and 2% showed anti-biofilm potential against Mutans streptococci. Ag at 1% and 2% and Sn at 2% showed a statistically significant difference to the control in WSR/SL (p < 0.05). The additions of metal methacrylate did not affect cell viability, being the adhesive resins statistically similar to controls. Leached metals of Ag were more than 100x higher than for Sn. Between the concentration tested, Ag and Sn methacrylate at 1% presented an anti-biofilm effect without altering the mechanical properties evaluated.