Even if you've lost a back tooth that no one sees, it's essential to replace it. Missing teeth do more than cause embarrassing gaps in your smile. In addition to affecting your ability to chew and speak, missing teeth can also cause gradual changes to the alignment of your remaining teeth. These changes not only affect your bite, but they have the potential to create more unsightly and unhealthy gaps in your smile. Furthermore, without the support of a complete set of teeth, facial contours can begin to sag, creating a more haggard look over time.