To remove braces select the first layer and duplicate it (control J). Grab the patch tool from the toolbar. Select around one part of the braces and drag it to a skin area. Then grab the clone tool and begin cloning the metal bars. Now grab the smudge tool and smudge the tooth to give them a more realistic look. Now grab the sharpen tool and sharpen the tooth. Now use the dodge tool on the tooth. Repeat these steps for each tooth.