I am sure many people at one time or another use their teeth to open a wrapper or to bite off a stubborn tag on a new shirt.  However if you are wanting to keep your teeth looking great then stop using your teeth as tools. Using your teeth in such a way can damage your teeth. You can easily crack or chip your teeth or cause poor jaw alignment  by wearing down your teeth unevenly. You also want to avoid using your teeth as hands. Do not hold items in your mouth even for a short time. Do not chew on items such as pens and pencils. You may have been told a a kid not to chew on your ice or you can chip your tooth, well that still rings true. Chewing on ice or using your teeth to crack open nuts, or biting on your finger nails all can lead to distorted teeth.