Aesthetic fillings

In the process of making the aesthetic fillings we use composite filling materials (plastic filled with ceramic granules). These types of materials have undergone a serious improvement in the last decade.
What is the process of making the tooth coloured filling? What are the advantages of the tooth coloured fillings?
Contrary to the traditional amalgam fillings it takes a lot more time to make a white filling. It needs a precise preparation and the dentist needs to follow the technological procedure very strictly. When these conditions are fulfilled, the average life span of the tooth coloured fillings can be up to 7 years, which is more or less the average life span of an amalgam filling. Their main advantage is the excellent aesthetic effect. Another big advantage is that a smaller amount of tooth material is needed to be sacrificed in the process of preparation. In some cases it is even possible to correct the shape of the tooth, or to repair the damaged surface of the tooth without any drilling.
What kinds of disadvantages can the tooth coloured fillings have? Should I have my amalgam fillings changed to white coloured fillings?
After putting in the filling some temporary biting sensitivity can emerge especially during the consumption of harder food (e.g., seeds, bread crust). The probability of this is increasing proportionally with the size of the filling (i.e., the bigger the filling the more sensitive). This is the reason why in cases where big fillings are required the use of inlays (see below) or crowns are recommended. If your old filling needs to be replaced, it’s practical to choose a tooth coloured, metal free solution for the new filling. The replacement of your tight sealing amalgam filling is only justified if it is aesthetically unpleasing or there is suspicion of sensitivity to amalgam (mercury). In general we can say that modern dentistry is striving to use the least possible amount of metal in the mouth cavity.