Porcelain inlays and onlays are different because of the casting of the porcelain, and I underline CASTING. Up until recently, there were only dental restorations made either of cast metal such as gold or other metals, which were used to make inlays, onlays or crowns or direct tooth placement materials such as silver-mercury alloys or tooth colored plastics. Porcelain inlays and onlays are a totally new technology. They do not require a metal base like porcelain fused to metal crown.
One of the greatest advantages is that now many teeth can be restored without crowning them. That means a tooth doesn’t have to be reduced all around. Now, only the old fillings need to be removed and if there are any missing parts of the tooth they can be restored with the cast porcelain. Also if there are any weak tips of the tooth, they can be covered with the cast porcelain without shaving down the good portion of the tooth. In other words, this cast porcelain restoration can be a much more conservative approach to rebuilding lost tooth structure. This means less trauma to the patients nerves inside the tooth ad also much nicer for the patients gums because their own tooth structure in still intact. These castings are invisible in the tooth. There are many different shades of porcelain to match a patient’s tooth color.
Let me explain why existing fillings fail. Most people have amalgams, which are approximately 50% mercury and 50% silver. There are a few other trace metals besides silver, but it is a very small percentage. Over time, mercury evaporates as a gas, leaving the silver particles with no matrix to bind them together. As a result, the tiny silver particles fall out of the restoration, leaving tiny voids at the junction of the tooth and the amalgam. Also silver forms an oxide layer which can be brushed or worn off much like polishing a sterling silver spoon which removes a small layer of the tarnished silver. Bacterial plaque begins to live in the tiny detached area at the edges of the fillings. This plaque forms acids which in turn dissolves calcium out of the tooth and can eventually lead to decay. Other causes of amalgam failure are deformation of the filling after years of chewing which can bend the fillings out from the tooth and eventually crack the amalgam or tooth structure itself. This is one reason many teeth break off portions of enamel when filled with amalgam. The other material used for fillings is called a composite. It is made of a plastic material filled with small particles of quartz, silica or porcelain called fillers. These are the white fillings many people have today. Like amalgams, they can be placed in one visit, as they are fluid when placed in the tooth and then set up. This material is aesthetic and is tooth colored but over time, the plastic begins to wear down when chewing and brushing, leaving the tooth structure standing higher than the filling. As the plastic wears, the fillers begin to fall out, leaving tiny voids on the surface and edges of restoration. Under hard chewing pressure, sometimes this restoration can deform and crack. Eventually the composite will have to be replaced when it fails. Now let me explain the porcelain casting technology and the reason it was developed. After the dentist removes the old filling or decay in the tooth, the tooth is prepared to receive the porcelain casting. An impression of the tooth is made which duplicates the tooth into a model upon which the casting is finally made. A technician makes the restoration on the model in wax. The wax pattern is placed into a high heat investment mold. A cube of specially prepared porcelain is heated to above 1800 F and becomes fluid enough to be injected under pressure into the mold to take the exact shape of the missing tooth structure. This porcelain is first made in controlled laboratory conditions with a very fine grain or small particles of porcelain. This is an advantage over many porcelains because the finer the porcelain particle, the denser, stronger and smoother the porcelain. In this case matching the surface hardness of the enamel. In other words, the porcelain is homogeneous with no filler of matrix to fall our or evaporate away. This leaves a hard durable smooth surface which has the wear ability of enamel, the look of enamel, and the feel of enamel. In addition, the porcelain casting is placed into he tooth by using an etching technology that binds the enamel and dentin in the porcelain for an almost water insoluble seal. The reason that this restoration was developed was to overcome all the shortcomings of the old materials and has allowed dentists to rebuild a patients tooth or teeth to a near state of perfection.
For more information on how this type of dental technology can meet your needs, call today to schedule your personal consultation. Our office is open Monday through Friday at 770-642-9900.