Everstick and ribbond fiber reinforced composites: scanning electron microscope (SEM) comparative analysis

The aim of the study is to compare morphological features and to evaluate wetting capabilities of two fiber-reinforced composites (FRCS); group A: Stick Tech(R), by Stick Tech Ltd, Turku, Finland, and group B: Ribbond(R), by Ribbond Inc., Seattle, Washington, USA, used in orthodontic retention, by scanning electron microscope (SEM). 6 groups were identified in relation to the fiber used, A: Everstick(R), B: Ribbond(R), and to the different times of exposition to a fluid wetting resin (Heliobond(R), by Schaan, Liechtenstein): A1-B1=0 seconds, A2-B2=5 seconds, A3-B3=5 minutes. Wetting was followed by 40 seconds of light curing with a conventional halogen curing light Optilux 501(R) (d) with a light intensity of 930 mW|cm(2) and a wavelength range of 400-505 nm Samples were SEM analyzed both in cross section and lengthwise. SEM observation revealed a lengthwise direction of cylindrically shaped fibers immersed in a metacrylate matrix in group A1 and straight but woven fibers in group B1. In both control groups voids ranging between 0 mu m and 20 mu m were visible between the fibers and groups of fibers. Groups A2 and B2 showed uniform coverage with Heliobond(R) and microcracks were visible. In cross section views it is apparent that wetting with Heliobond(R) for just 5 seconds was not sufficient for the adhesive to impregnate the fibers deeply. Groups A3 and B3 revealed a deeper penetration of Heliobond(R); voids ranging between 5 mu m and 15 mu m could be observed only in the deepest portion of the fiber. The fiber's preparation plays a decisive role: a longer fiber wetting time with fluid resin before curing, enhances the morphological features of FRC, making them more suitable for passive and active orthodontic systems, periodontology or prosthetic dentistry