It is generally known that there are 2 types of tooth filling: the black silverish ones (or amalgam) and the white tooth-coloured ones (composite). But the thing that we always wonder would be, which one is better? Is it the black ones, because it has been used as tooth filling material for more than a century now; or is it the white ones, simply because it looks better?
Let the competition begin, and I will let you be the judge. ;-)
Round 1: strength
Amalgam is known for its high strength; it can stand up to 350MPa of pressure (even higher than natural teeth – 250MPA). It is also not affected by surrounding factors such as saliva and blood. Problem is, its strength can only be achieve in bulk; means the filling must be at least 1.5 mm thick (or the hole must be 1.5mm deep) or it will easily fell.
Composite, on the other hand, has similar strength with our natural teeth (260MPa). It can be used on a shallow cavity, but its strength can easily be altered by surrounding factors. For example, if it is mixed with our saliva or blood, its strength will become low. Also if composite is exposed to the dental overhead light for too long, its composition can also be altered.
Round 2: cost
Cost of amalgam is about 30% less as compared to composite. Also, a relatively greater amount of time and skill is needed for your dentist to place a white filling as compared to an amalgam filling. Your dentist has to make sure the cavity prepared is free of blood and moisture. Also, composite cannot bond itself to tooth surface. It needs extra help, a bonding agent; which equals to extra cost.
Round 3: bonding strength
Amalgam bond itself to our tooth surface via mechanical retention, means your dentist has to prepare a ‘lock’ or an ‘undercut’ before amalgam is placed. Think ‘lock and key’. Composite, on the other hand, depends on chemical retention. Your dentist has to place the bonding agent first before your tooth can be filled with composite.
Hmm.. its pretty obvious, don’t you think? Composite is tooth coloured, it even has different colours so your dentist can match the shades with your exact tooth colour. We can even do it in layers you know, if the neck of your tooth has different shade than the tip of your tooth. Amalgam is… well..
Round 5: composition
This might be new for some of you. For your info, amalgam consists of mixture of metal alloy and mercury, on a 1:1 ratio. Mercury, as is generally known, is a highly unstable element. A little bit of mercury is released when tooth is being filled, or when amalgam filling is removed, and even during chewing. Side effect of mercury ingestion includes personality change, memory loss, psychological distress and a lot of others. However, rest assured, there are no scientific evidence that shows dental amalgam does affect our general heath. Our Health Ministry has produced a Position Statement on use of dental amalgam in 2002. Ask your dentist for a copy of you want to read it.
Composite on the other hand is pretty safe. Manufacturers of dental composite upon producing new composite product has to comply with American National Standard/American Dental Association Document No 41 for Recommended Standard Practices for Biological Evaluation of Dental Materials, 1982 before it can be distributed. This evaluation consists of Cytotoxicity, Mutagenicity, Sensitivity and Carcinogenicity test. So no worries.
Round 6: life span
Generally, amalgam has longer life span as compared to composite. Van Nieuwenhuysen in 2003 and Forss in 2001 conducted a comparison study between dental composite fillings and dental amalgam fillings. They found an average life span of 12 to 12.8 years for amalgam fillings and 5 to 7.8 years for composite fillings. However, composite is an evolving material. Every year dentists are introduced to composite that has better strength, durability, polishability, aesthetics.. so I am pretty sure its life span and strength will improve with time.
And the winner is…