Thursday, April 24, 2008

black or white

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.

Round 4: aesthetics

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…

Tuesday, April 22, 2008

the power to choose

As parents, we always wants the best for our children, and we always wonder whether the things we did is the best for them. We always choose the best milk formula ‘with highest content of AHA,DHA, so forth’; the best diapers ‘that can stand up to 7-8 wets’, the best shoes that ‘allows the feet to grow’,.. the list goes on. Same goes when it comes to choosing dental products. The best toothpaste for our toddler must be the one with highest concentration of fluoride, since fluoride can help fight tooth decay, right?


The actual fact is, while fluoride does help in fighting tooth decay, our body (also our children’s) only need about 0.05-0.07mg fluoride /kg body weight. This can easily be achieved by drinking plain water or eating food cooked using water. In Malaysia, water fluoridation (putting fluoride into our water supply) started in Johor in 1966 and becomes a nationwide policy in 1972; and it has been significant in reducing tooth decay by strengthening the enamel (the outer layer of the tooth).

The fluoride level in our commercially available toothpaste are being regulated in between 550 – 1500 ppm (parts per million) and it is safe to be used by us, adults, for 2 reason:

- the fluoride will act as a topical supplement; i.e. it will only makes contact to the tooth surface since we do not swallow the toothpaste

- our average body weight (50-70kg) can sustain up to 0.10mg of fluoride/kg body weight, and one pea-sized toothpaste contains about 1mg of 1000 ppm fluoride. Confused? Let’s just say it’s safe for us to swallow one whole tube of toothpaste without risking any side effect.

Unfortunately, both reason is exactly why our children (age 6 months to 6 years) should not use fluoridated toothpaste. Pray tell, how can you confirm your child would not ‘accidentally’ swallow the yummy orange-flavoured toothpaste? Even though we have told them not to?

The next question you would ask would be: how does excessive fluoride consumption affects our children?

Let me introduce you to a new vocabulary:

It is a damage in tooth development, occurs between the ages of 6 months to 5 years, from the overexposure to fluoride. It will present itself as intrinsic (read: internal) staining of the permanent teeth, so the teeth will have whitish specks (mild fluorosis) up to brownish black (severe fluorosis).

Besides fluorosis, which is a known and proven side effect of excessive fluoride intake, the less known side effect is more worrisome, such as effects to their IQ and also to the kidneys and liver function in children. However, these side effects are very much debatable and more questionable. We should just leave the issue to the experts, I guess.

Trouble is, there is not many kids toothpaste that does not contain fluoride. I can introduce some brands that are available commercially, but please share with me if you know of others.

Pureen fluoride free kids toothpaste, retail at RM3.50

First Teeth A Natural Enzyme Baby Toothpaste, retail at RM35.00, available only at selected pharmacies (and a tad too expensive, if I may add)

ProdentalB children’s toothpaste, retail at RM4.00 though it’s really difficult to get this in stores. I have no idea why, maybe their distribution is limited.

Don’t get me wrong here. I’m not saying that you should ban fluoridated toothpaste from your household, okay. Fluoride is extremely important in remineralizing (strengthening) tooth surface that might have early signs of decay, and the side effects are relatively small compared to the positive effects. Plus, there are treatments available for those who have fluorosis. But prevention is much better, isn’t it?

For me, I keep both fluoridated and nonfluoridated toothpaste for my daughter. I use the nonfluoridated one daily and the fluoridated one like once in 2-3 weeks. Besides that you can always monitor or help your children while they are brushing their teeth, make sure they did not swallow any of the toothpaste if you are using the fluoridated ones. Also your dentist can give your child what we call ‘fluoride therapy’- which can be done once every 3-6 months, and very beneficial for sweet-toothed children. For babies, you can opt for the First Teeth toothpaste, or your dentist should be able to prescribe your child a suitable alternative. Or you can always not use anything, the wet towel can already do wonders.