Since verbal communication is going to play a prominent role in your interview, you better make sure you knock 'em dead with your answers, not your breath.
Try to maintain good oral health and hygiene at all times, and especially in the lead-up to your interview. In general, drink water or use products with fluoride for strong teeth.
If you haven't been to a dentist in a while and can afford to do so, invest in your smile. By maintaining a regimen of good dental hygiene, you'll have a successful-looking, confident smile: clean white teeth, healthy pink gums and good breath.
At least twice a day, you want to brush and floss your teeth. To do so, place the toothbrush at a 45-degree angle toward the gumline, but be sure to brush away from the gumline. Use short back-and-forth strokes to brush every side of every tooth. Brush your tongue and the roof of your mouth to get rid of excess bacteria that contributes to bad breath.
Hold floss taut between thumbs and forefingers, and slide it gently between your teeth. Floss with the curve of each tooth. Go beneath the gum line, but gently -- don't hurt or cut your gums. Use a clean section of floss for each tooth
Finally, remember to take breath mints to your interview! You don't want your prospects diminished by the ill-advised consumption of a can of soda before you meet your potential employer.
Next: Hair to get you hired.