When a silver filling is placed it is metal that has been packed/wedged into a prepared space. A properly bonded Biomimetic composite resin restoration is placed incrementally and reconnects the sides of the tooth. Not only do these restorations look more natural but they also function more naturally. Like all hard materials, the hard metal filling does not absorb chewing stress but transmits the forces to the inside of the tooth. Composite Resin restorations are more flexible and similar to the flexible stress absorbing dentin found inside the tooth. These materials absorb chewing forces and when properly bonded dissipate them. evenly and similarly to the natural tooth structure they are replacing and mimicking. The decreases the risk of cracks forming under cusps and/or marginal ridges as seen over time with metal fillings
Unfortunately, poorly bonded and/or poorly placed composite restorations will perform worse that metal fillings. The disconnected parts of the tooth will flex back and forth much like with metal fillings and in large fillings can lead to cracking under cusps and/or through marginal ridges. Additionally, one of the benefits of metal amalgam fillings is that they are bacteria resistant (bacteriostatic). Therefore it is difficult for bacteria to grow underneath them without a very large gap being present. Composite Resin restorations are not bacteria resistant at all and bacteria can grown under very small and imperceptible gaps between the restoration and the tooth. A poorly bonded composite resin is not a restoration but simply a white colored filling – that generally perform more poorly than silver amalgam fillings.
This is why it is important to use proper isolation, bonding agents, and composite layering techniques to ensure the composite restoration stays bonded long term so that you can receive the benefits of a bonded composite restoration long term. Biomimetic Dentists undergo specialized training in bonding, material science, and composite placement techniques after dental school.”