by Vu Le
The best dental material for a filling will always be the one you never had to use. ALL dental materials have pros and cons. Because the human mouth is a rough place to be, all dental materials eventually fail. This is why oral hygiene and diet are so important.
One dental material that has been around for centuries is amalgam, a mix of metals used to fill cavities in teeth. Today’s alloys are predominantly mercury and silver. There’s a lot of good things about amalgam. It’s very forgiving of technique, blood and saliva. Even the most mediocre practitioner can place a long lasting amalgam, though it still takes some skill to shape them well. When they are used appropriately and proficiently, silver fillings easily last decades--I have two fifteen year old silver fillings in my mouth as I write this. Many of my senior patients have fillings placed in their teens. You don’t need very fancy equipment. It’s very inexpensive to buy and fast to condense, which in turn makes fillings inexpensive. That makes it a natural fit for HMO, non-profit and government funded clinics. Amalgam is arguably still a good choice for cases where the patient cannot remain still for long periods of time (think cerebral palsy) and sedation is not an option.
So why did I stop placing amalgam over nine years ago? The easiest reason is consumer demand: silver is just plain ugly in the age of white composites and ceramics. Nobody wants it, and since we opened the practice in 2005, only one or two patients requested silver in order to save $20 on a filling. So it became economically foolish to maintain inventory on something nobody wanted. We are in “the OC”, after all. The second reason I stopped placing it was the lack of adhesion; silver fillings don’t really stick to teeth, whereas white fillings are bonded. This means when you chew side to side, white fillings provide slightly more support. We’ve seen lots of cusps fracture away from a large silver filling. When you have a large filling with thin walls of enamel on either side, those thin walls can break off. White fillings hold the tooth together a bit better, which results in a stronger tooth overall. At least half of the crowns I do today are from the overly large silver fillings of yesterday. The third reason I don’t like silver fillings is the darkening of nearby tissues. The metal ions from the silver filling leach into tooth and gums nearby, creating a permanent darkening. If a scrap of silver filling gets trapped in the gums, it makes a black tattoo. In the tooth, it often creates a dark discoloration that bleaching cannot resolve.
Most dentists, including myself, place tooth colored composite resin as filling material. Compared silver amalgam, it’s much more technique sensitive. Even a drop of stray saliva or blood will cause a filling to fall out or fail prematurely. No composite has the compressive strength or wear resistance of amalgam. So while you could build an entire tooth out of amalgam in a pinch, you would never want to do so with composite resins. The average lifespan of a white filling is short--around 3 to 5 years per Delta Dental statistics. But composites are much more esthetic, more repairable, and as mentioned before they are bonded to the tooth with adhesive. This not only reinforces the tooth, it also allows for smaller, less invasive reduction of tooth structure, particularly on root surfaces, in between back teeth, and especially on front teeth. Repairing a chipped front tooth used to require a crown; now it can often be done with a simple composite bonding.
Our policy on tooth restoration is to do the most conservative restoration possible, with increasing consideration towards durability. In practical terms, that means white fillings for small to medium sized cavities, and ceramic inlays, onlays and crowns to address larger issues. We do not recommend the removal of silver fillings to treat or prevent medical conditions, in accordance with California law. Of course, we do recommend the prompt replacement of ANY dental filling material if there is evidence of fracture, recurrent decay, or leakage. And if you’d like to make your silver-filled mouth beautiful again, we can do that, too.
Which brings me back to the point I made before. Every dental material has its place, both ugly old silver fillings and the newer white composite resins. More and more, we are placing even longer lasting dental ceramics. But all of them can eventually fail. This leads to a larger filling, inlay, onlay or crown. No matter how good our restorative options get, no matter how good your dentist is, the most effective dental material of them all may not be gold, silver, ceramic or composite. It just might be good old dental floss.