Fig. 324: Diagrammatic drawing of horizontal cross sections of teeth near the cervical level at which point their approximal surfaces tend [...] to become concave

Abstract

Left - Straight lines representing taut strands of dental floss placed at various angles to show that the concave surfaces cannot possibly be reached effectively by the floss in cleansing. Right - Cleansing action of bristles in similar approximal concavities made possible by the leverage of the bristles through the circular stroke of the brushhead. [...]. The necessity of adequate length of bristles for intraproximal brushing is here apparent.

Black & white drawing