Effects of quaternary ammonium-methacrylates on the mechanical properties of unfilled resins

Abstract

Objectives Adding antimicrobial/anti-MMP quaternary ammonium methacrylates (QAMs) to comonomer blends should not weaken the mechanical properties of dental resins. This work evaluated the degree conversion and mechanical properties of BisGMA/TEGDMA/HEMA (60:30:10) containing 0–15 mass% QAMs A–E (A:2-acryloxyethyltrimethyl ammonium chloride; B:[3-(methacryloylamino)propyl]trimethylammonium chloride; C:[2-(methacryloxy)ethyl] trimethyl ammonium chloride; D:diallyldimethyl ammonium chloride; E:2-(methacryloyloxy) ethyltrimethyl ammonium methyl sulfate. Methods Unfilled resins with and without QAM were placed on ATR-FTIR and light-polymerized for 20 s in a thin film t 30°C. Unfilled resin beams were casted from square hollow glass tubings. Half of the beams were tested after 3 days of drying (control); the other half were tested wet after 3 days of water storage. Results Addition of QAMs in control resins significantly increased conversion 600s after light termination, with the exception of 5% MAPTAC (p<0.05). Increase of QAM content within a formulation significantly increased conversion. Control beams gave dry Young’s moduli of ~700 MPa. Addition of 5, 10 or 15 mass% QAMs produced significant reductions in dry Young’s moduli except for 5% B or C. 15 mass% A, B and C lowered the wet Young’s moduli of the resin beams by more than 30%. The ultimate tensile stress (UTS) of control dry resin was 89±11 MPa. Addition of 5–10 mass% QAMs had no adverse effect on the dry UTS. After water storage, the UTS of all resin blends fell significantly (p<0.05), especially when 15 wt% QAMs was added. Control dry beams gave fracture toughness (KIC) values of 0.88±0.1 MPa√m. Wet values were significantly higher at 1.02±0.06 (p<0.05). KIC of dry beams varied from 0.85±0.08 at 5% QAMs to 0.49±0.05 at 15% QAMs. Wet beams gave KIC values of 1.02±0.06 MPa√m that fell to 0.23±0.01 at 15% QAMs. Significance Addition of 10% QAMs increased the degree of conversion of unfilled resins, but lowered wet toughness and UTS; addition of 15% QAMs lowered the mechanical properties of wet resins below acceptable levels.

Influence of addition of [2-(methacryloyloxy)ethyl]trimethylammonium chloride to an experimental adhesive

“…These findings indicate that incorporation of METAC had no adverse influence on the curing behavior of Bis-GMA/TEGDMA/HEMA-based adhesive resin. Although there is a statistically significant difference in the degree of conversion, its values corroborate those of the literature, 4 but it is not possible to state they will be clinically significant. METAC is a monomethacrylate 16 and there may have been fewer unreacted double bonds after the reaction, not indicating reduced polymerization, though.…”

“…4,5,6,7 The results of the present study indicate that METAC is a promising antibacterial agent when added to an adhesive system.…”

“…4 This copolymerization immobilizes the antibacterial agent, preventing its leakage, which could result in material with poor physical and chemical properties. 12 The softening test is an alternative method for crosslink density evaluation.…”

“…2,3 Thus, antibacterial agents have been added to adhesive systems as an effective dental treatment strategy. 4,5,6,7 The use of antibacterial agents leads to inactivation of bacteria and may hamper dental caries progression. 8 Furthermore, the antibacterial property of adhesive systems could bring an additional benefit to the conservative management of carious Fabrício Mezzomo COLLARES (a) Vicente Castelo Branco LEITUNE (a) Patrícia FRANKEN (a) Clarissa Fatturi PAROLLO (b) Fabrício Aulo OGLIARI (c) Susana Maria Werner SAMUEL (a) lesions 9,10,11 by improving the success and longevity of restorations.…”

Threats to adhesive/dentin interfacial integrity and next generation bio‐enabled multifunctional adhesives

“…QAM‐based composites, adhesives, and primers offer promise in terms of antimicrobial activity but suffer from important deficiencies . QAMs may alter the polymer's network structure, decrease monomer‐to‐polymer conversion, decrease mechanical properties, and increase sorption of ethanol, water, and other solvents . Furthermore, the cationic monomer's high affinity for cell membranes is not limited to bacteria—since adhesive and composite polymerization is incomplete, unreacted monomer could also leach into tissues, where its high affinity for cell membranes raises cytotoxicity concerns .…”