Fillings replace a part of the tooth that has been lost due to a cavity or accidental damage. The same material is used in bonding techniques for cosmetic reasons as well.
Add the filling material incrementally, shaping and contouring it to your tooth's shape
Harden the material with a "curing" light
Trim and polish to finish
And The Benefits Are...
Diagnostic: dental x-rays, either film or digital, cannot go through metal fillings for proper diagnosis. Dental X-rays can go through plastic.
Wear: metal fillings corrode after a certain period of time; plastic fillings wear down, since they are slightly softer than natural tooth enamel.
Durability: once a silver filling has recurrent decay (or has a new cavity), the entire restoration needs to be removed and replaced. This can damage the tooth by removing additional tooth structure. This is unnecessary with tooth-colored fillings. If there is recurrent decay, an x-ray can determine how far the damage goes, so only that part of the impaired restoration needs to be removed and replaced. Less trauma to the tooth means less chance of post-operative sensitivity.