Influence of placement instruments on handling of dental composite materials

Applicability and stickiness of dental composites are influential factors for the properties of those materials and so indirectly affect function, longevity and esthetics of composite restorations in the clinic. Thus, this in vitro study aimed for the influence of different placement instruments' diameter, geometries and coatings on the handling of uncured resin composite materials.

A survey about application technique of resin composites, placement instrument diameter, geometry and coating, and application temperature was answered by 55 German dentists in private practice. Due to these data diverse composite placement instruments were used to perform tensile tests on PMMA plates with application forces of 1N and 2N (v=35mm/min) at 25 and 37°C. Following the dosing of a certain amount of the composite (nanohybrid, microhybrid) to the tip of the composite placement instrument, unplugging forces were determined after application and unplugging was performed.

Unplugging forces were statistically significant different and varied between 0.27N and 1.14N. Stickiness of dental composites was dependent on the composite material itself as well as diameter, geometry and coating of the placement instruments.

Pre-clinical testing of composite materials' stickiness by unplugging forces facilitates the assessment of its handling properties.