Frictional coefficient during flossing of teeth

This in-vitro study aimed to develop a technique to measure the frictional forces and determine the frictional coefficient (μ) associated with the rubbing of dental floss against teeth. Incorrect flossing technique and the etiology of grooves at the cementoenamel junction (CEJ) of proximal area of teeth has long been a controversial topic. We hypothesized that the μ between teeth surfaces and dental floss is affected by contact angulation. Tests were conducted using two different types of dental floss (waxed and unwaxed nylon) on different surfaces (enamel, dentine, smooth and rough glass rods) under different moisture conditions (dry and wet). The μ generated by performing C-shape flossing was measured, using the Capstan equation, at constant load (100g) over different flossing contact sliding angulations. In addition, the surface characteristics of intact and used nylon flosses were compared using a scanning electron microscope (SEM). The mean μ was highest with a smooth glass rod (0.42±0.11), followed by rough glass rods (0.30±0.07), dry enamel (0.27±0.08), wet enamel (0.23±0.06), then dentine (0.18±0.04). Moreover, higher μ was associated with waxed floss when used against dry enamel, smooth and rough glass rods (P