Dental Fillings: Types and Reasons for Their Use

Filling cavities is what we do. Fillings are required for a bunch of reasons but three of the main ones are cavities (decay), fracture of the tooth or certain types of wear.


1.) Sometimes despite our best efforts (or lack of effort), we get cavities. Cavities are bacteria filled holes in teeth. These bacteria feed off of what we eat and grow in number. The byproducts of bacteria are extremely acidic in nature and weaken tooth structure. As the tooth weakens the cavities get further and further into the tooth eventually causing pain or tooth death. 


So... it is in the best interests of our patients to detect these cavities as early as possible. Early detection can help us avoid pain, root canals and crowns. Many times if a cavity is sensitive or painful it is often too late to save it with a filling alone. The belief that “since I can’t feel it I won’t fill it” can lead to devastating results. 


2.) Fractures are another reason for filling teeth. Cracks around old fillings or ones that are caused by trauma can be filled if they are not too large. The larger they are the more chance there is for it to need a crown to fix.


3.) There are some types of tooth wear that may require a filling to fix. Sometimes over aggressive brushing techniques, grinding of teeth and conditions like acid reflux can cause abnormal wear on the teeth. If this wear extends into the dentin (softer part of the tooth) sensitivity and undermining of the tooth can occur, weakening the tooth and creating greater potential for fracture of the tooth. Filling in these areas prevents further wear, lessens sensitivity and strengthens the tooth. 


Filling Materials: 


There are a lot of different filling materials but the most common are composite and amalgam. 


1.) Composite materials are the white filling materials. There are many advantages to using these types of restorative materials. They are chemically bonded to the tooth. This gives them a lot of strength and lessens the chance of decay starting around them. The bonding materials used today have gotten better and better as time goes by. The one that we use in our office has the highest bond strength of any bonding agent on the market and is charged with fluoride. The fluoride in the bonding agent leaches into the tooth over time and helps strengthen the edges of the cavity to help prevent further decay from leaking down around the new filling. Another benefit to using composite filling material is that since it is bonded less tooth structure needs to be removed to get the filling to “stick.” More tooth structure means that the tooth can go through more filling cycles before needing a crown. Composites are very strong when done well. They are similar in hardness to the rest of your tooth so they expand, contract and flex well with your teeth. Composites are the most conservative method for filling teeth and are very reliable.

2.) Amalgam fillings are the silver fillings that are gradually getting phased out of more and more dental offices as composite filling materials become the standard. There is a lot of alarm surrounding these types of filling materials because of their mercury content. Every few years 60 Minutes, 20/20 or some other documentary style news show gets people up in arms about silver fillings. The truth of the matter is that they have been shown again and again to be of minimal concern for public safety. Once the amalgam sets there is insignificant amounts of mercury vapor released. As a matter of fact you are exposed to many times the level of mercury vapor on a daily basis. 


All that being said, we don’t use silver fillings in our office. I feel that composite restorations are more suitable as a filling material in their current state. Because amalgams are metals, they have a tendency to expand and contract during hot and cold cycles within the mouth (drinking ice water or hot coffee for instance). This puts large amounts of stress on the tooth and can be responsible for fractures around old fillings. When amalgams set they also expand. Their primary retention comes from mechanical pressure placed on the cavity walls. In larger fillings this pressure can also result in tooth fracture. Beyond that there are risk factors with mercury vapor when amalgams are being mixed and placed for dental personnel.