the size of the restoration is actually determined by the extent of caries (decay) which has to be removed. the composite restoration is a suitable restoration for a small cavity preparation. if the extent of the caries is small to medium size leaving most of the original tooth intact the composite could serve very well and for many years. however it is a technique-sensitive procedure that requires careful isolation and slow incremental filling of the cavity. if you are going to a place that works very fast and sees many patients you might want to reconsider this type of restoration. if done in a rushed fashion the composite restoration will not last long. this is also why most dentists will charge you more for the composite over the amalgam. the amalgam restoration has proven itself over the years and is a material which is not so technique-sensitive. the least-skilled operator can deliver a decent amalgam with good predictability over time. the material is very forgiving and can handle medium-sized restorations quite well. it is the restoration of choice if you are going to a volume-based office such as a union/insurance dentist. they do have to see many patients in a day and might find it difficult to allocate the extra time in the schedule that is required for a proper composite restoration. the most important either way is good oral hygiene and care after the restoration is placed. as long as good x-rays and cleaning schedule is observed either restoration will last you over time. the best advice is on which restoration to choose is from your dentist. he/she has the x-rays and the clinical examination to advise you properly. . and as usual a second opinion from a prosthodontist is always a good option.
what's the difference between a composite and amalgam filling? does a composite allow smaller holes to be drilled?