Porcelain Crown for Front Tooth

Porcelain is a very beautiful, life-like restorative material used often for crowns and veneers on front teeth. One downside to porcelain is that it is one of the weaker materials in dentistry, which is why it is contraindicated in posterior teeth (molars in the back for example). There are other, stronger materials such as Emax that are also beautiful and life-like that may be a better choice for front teeth. As others have mentioned, placing one single crown on a front tooth is one of the more difficult procedures in dentistry. So make sure you pick a skilled dentist that works with a cosmetic dental lab and make sure that you preview the crown BEFORE it is permanently cemented so you can approve of its shape, shade, and size. 
As far as how long it will last, that depends on you, your dentist, and the material. There really is no specific answer for how long the crowns will last but if you care for your teeth and get regular dental visits and have selected a skill dentist, the crown should last some time. Hope this helps!

Hi:
The replacement of crowns depend on three factors:
1.  If you get gum recession where the roots of the tooth show while smiling, you may want to get longer crown to cover the roots.
2.  Chipping or fracturing the crown
3.  Getting decay where the crown meets the tooth.
The actual procelain material does not actually breakdown over time.  Both Zirconium and Emax crowns are strong, however Emax is more aesthetic.Best,Dr. Maddahi