Q Brush Interproximal Brush, Standard Handle. Q Brushes are available in eight sizes. Wires are coated and are safe for crowns, veneers, implants, and fixed appliances. Brush handles are color-coded for easy size identification. Recommended use: Size 0 (gray) is best between lower front teeth and for cleaning under lower orthodontic retainer wires. Size 1 (purple) and size 2 (white) work well between upper front teeth and lower side teeth (bicuspids). Size 3 (yellow) works well on back teeth (molars). Size 4 (red), size 5 (blue), size 6 (teal) and size 7 (black) work best in areas where there are wide spaces between teeth. Size 5 (blue), size 6 (teal) and size 7 (black) work well with braces to clean under wires and around orthodontic brackets. Size 6 (teal) and size 7 (black) work well for post-operative periodontal patients. These sizes and uses are recommendations only. Q Brush is a personal product and should be fitted for your personal use. Always follow written instructions. Keep away from children.