Physical/Mechanical and Antibacterial Properties of Orthodontic Adhesives Containing Calcium Phosphate and Nisin

Abstract

Enamel demineralization around orthodontic adhesive is a common esthetic concern during orthodontic treatment. The aim of this study was to prepare orthodontic adhesives containing monocalcium phosphate monohydrate (MCPM) and nisin to enable mineralizing and antibacterial actions. The physicomechanical properties and the inhibition of S. mutans growth of the adhesives with added MCPM (5, 10 wt %) and nisin (5, 10 wt %) were examined. Transbond XT (Trans) was used as the commercial comparison. The adhesive containing a low level of MCPM showed significantly higher monomer conversion (42–62%) than Trans (38%) (p < 0.05). Materials with additives showed lower monomer conversion (p < 0.05), biaxial flexural strength (p < 0.05), and shear bond strength to enamel than those of a control. Additives increased water sorption and solubility of the experimental materials. The addition of MCPM encouraged Ca and P ion release, and the precipitation of calcium phosphate at the bonding interface. The growth of S. mutans in all the groups was comparable (p > 0.05). In conclusion, experimental orthodontic adhesives with additives showed comparable conversion but lesser mechanical properties than the commercial material. The materials showed no antibacterial action, but exhibited ion release and calcium phosphate precipitation. These properties may promote remineralization of the demineralized enamel.

Physical/mechanical and antibacterial properties of orthodontic adhesives containing Sr-bioactive glass nanoparticles, calcium phosphate, and andrographolide

“…The experimental orthodontic adhesives were prepared using the protocol of a previous study 12 . Briefly, the liquid phase of the adhesives contained 70 wt% urethane dimethacrylate (Sigma–Aldrich, St. Louis, MO, USA), 26 wt% triethyleneglycol dimethacrylate (Sigma–Aldrich), 3 wt% 2-hydroxyethyl methacrylate (Sigma–Aldrich), and 1 wt% camphorquinone (Sigma–Aldrich).…”

“…The FTIR spectra in the region of 700–4000 cm −1 were recorded from the bottom of each material. The degree of monomer conversion (DC) was then calculated using the following equation 12 . where and are the absorbance of the C–O peak (1320 cm −1 ) 28 above the baseline at 1335 cm −1 before and after curing at time t , respectively.…”

“…The maximal load (F, Newton) before the debonding of the bracket was recorded. The shear bond strength of materials to enamel (SBS, Pa) was then calculated using the following equation 12 . where A is the area of the bonding interface (m 2 ).…”

“…The test was performed according to the protocol used in the previous study 12 . The specimen (n = 1) was prepared according to the SBS test.…”

“…Commercially available monocalcium phosphate monohydrate (MCPM) was incorporated into resin-based materials in previous studies 10 , 11 . The use of MCPM at high concentrations (10–20 wt%) substantially enhanced the precipitation of hydroxyapatite 10 – 12 , which was expected to promote remineralizing effects at the tooth-composite interface. However, the high solubility of MCPM (Ca/P ratio = 0.5) could lead to excessive water sorption, polymer plasticization, and significant reductions in the mechanical strengths of orthodontic adhesives 12 .…”