Physical properties of a periodontal dressing material

Further characterization has been undertaken of a visible light cured periodontal dressing material (Barricaid), which has been shown to exhibit superior physical properties to those of the standard (chemically curing) dressing materials. In particular, water sorption and solubility were studied, with a greater solubility found at 37 degrees than at 23 degrees with little further increase at 50 degrees C. Water sorption increased from 23 degrees C to 37 degrees C but decreased at 50 degrees C. Cure depth, determined by a penetrometer method, showed a constant resistance of 5.8 kg to probe penetration to a material thickness of 11 mm but resistance to penetrometer penetration, i.e. the level of cure, decreased sharply at greater thickness. The tensile strength of the material was unchanged when immersed up to 7 days in water at 37 degrees C, indicating a highly coherent material unaffected by water over a period corresponding to average clinical use. Previous studies showed that interlocking into the embrasures was required for adequate adhesion of Barricaid. To overcome this problem, teeth were etched and a bonding agent applied to the etched enamel surface. This chemo-mechanical lock gave an immediate adhesion value of 43.94 MPa, which decreased to 37.17 MPa at 7 days. The immediate adhesion value without etching and bonding was 34.23 MPa which decreased to 19.32 MPa at 7 days. Soaking decreased adhesion to enamel, but the effect was markedly less when the enamel was pretreated by etching and priming.