Sometimes teeth do not form properly.  In this case, this lateral incisor, commonly called a peg lateral, is too thin and misshapen.  Bonding was performed to correct the problem.  Although the cosmetic results are very good, this is only meant to be temporary.  The best long term solution for this problem is covering the tooth with a porcelain laminate.  This thin sheet of porcelain is extremely durable and color stable, and many times lasts over twenty years.