This pilot study will compare 1) Silver diamine fluoride (SDF) and fluoride varnish to 2) Placebo and fluoride varnish (conventional prevention) in the management of early approximal carious lesions. Early approximal carious lesions refers to decay between teeth, diagnosed with radiographs, not extending more than 1/3 of the way into dentin. Management of early approximal carious lesions refers to halting lesion progression, or encouraging lesion reversal after an early carious lesion is detected.