The Tooth about White Fillings

Recently the world of dentistry has converted to predominantly white fillings as opposed to the silver fillings. What people don't really understand is what these fillings are and what their limitations are. Briefly I will say that the silver fillings known as Amalgam are very strong, safe, and reliable fillings. I will go into detail about them in another post. Lets talk about white filling known as Composite.

WHAT IS COMPOSITE? Scientifically they are called resin, but simple put, its plastic, very hard plastic. It is comes in 2 basic forms: Squishy and flowy also known as Packable and Flowable. Both of these, when hit by an intense blue light become "cured" and turn very very hard. Most dentists use both of the squishy and the flowy - the squishy type is stronger and has been engineered to be strong enough to withstand most biting forces. The flowy type has been engineered to be extra smooth and polishes to be real shiny. It can reach little nooks and cranies that the squishy type cannot.

HOW IS A WHITE FILLING DONE? Unlike other fillings or restorations, Composite fillings do not rely on a wedging effect to stay in the mouth. They rely on bonding or chemically attaching to the tooth. The benefit of this is the dentist can cut less or zero tooth away to put a composite filling on. Simple place the chemicals on the tooth to prepare it and then put the filling material and then blue light (aka cure). By the way if you taste something funky during all of this, it is the chemicals used to bond to the tooth. The side effect of this is that whenever these fillings have problems, they don't stay in - they pop out. Other fillings, when there are problems, they stay in even if they are decayed all around. You can view this as a positive or negative thing.

CAN WHITE FILLINGS BE USED ALL THE TIME? The short answer is yes, but the real answer is no. They CAN be used all the time, but they probably shouldn't. One of the major weaknesses is  that it relies on the tooth being completely dry when it is done. Often times your tongue or even the moisture in your breath can disturb this and make the filling not as strong as it was designed to be. When working in the back, this can be especially challenges to get a strong bond.

WHAT ARE THE DRAWBACKS? Many patients get sensitivity to cold and sweets after composite fillings are done especially when the cavity is deeper. There are several reasons this can happen. The first is that the inner layers have the tooth have nerves embedded in them and the filling material, because it is plastic has a very slight flex to it. This flexing will disturb those nerves. Also, because of the strength of the Packable composite, if the filling was made to be too high you will not be able to grind it down and that tooth will take more force than other teeth leading to sensitivity. Dentists will always check the bite first to make sure this is not the problem. Another drawback is that plastic just isn't as strong as metal and in some strong jawed patients, it will be strong enough and will break.