As a dentist, few things are more unnerving than an emergency patient with a missing front tooth or crown. A few weeks ago we had a new patient emergency visit. She had lost the crown on a lateral incisor, one of the small teeth right next to the two front teeth. To make matters worse, this tooth had previously been root canal treated, and the root canal treatment was failing. Finally, the tooth was broken off at the gumline. The decision to save a tooth in such condition is not easy. Having an existing root canal treatment, and a fracture at the gumline, the tooth is in pretty bad shape. However, the patient wanted the tooth fixed quickly, and she preferred that we save the tooth rather than replace it with an implant. Ultimately, we decided to treat the tooth with a root canal re-treat, post, core, and crown.
Root Canal Re-Treat
At first, our patient was hoping we could just cement her crown back on the tooth. We explained to her that in order to have a good chance at saving this tooth, we need to replace the existing root canal treatment with a new one for two reasons. One, the existing root-canal treatment is failing. Two, we need to put a post inside the root of the tooth to support the crown.
A root canal is basically an internal filling. To perform a root canal, we cut a hole to the middle of the tooth where the nerve and blood vessels live. We then carefully remove all of these soft tissues and replace them with a sealer. In most cases, we use gutta-percha, a rubbery and bio-compatible filling material.
The first part of the process involves removing the existing root canal filling material. To do this, we use a combination of sharp files and chloroform. The chloroform acts as a solvent that dissolves the gutta-percha filling material. After we remove all of the filling material, we clean out the inside of the tooth using various medicaments. We then measure the length of the tooth and seal it with new gutta-percha material.
Post and Core
After we successfully seal the root canal, we place a post. The post goes into the root of the tooth and and helps support the crown. The post holds the crown to the root of the tooth. You can see in the images below how the post joins the crown and the root of the tooth. The material between the crown and the post is the core buildup.
Crown
Once I am satisfied that the root canal re-treatment has a good chance of success, and the post and core buildup are stable, we prepare the tooth for a crown. Our patient came to us with a broken front tooth, and she left with a temporary crown the same day. In just two weeks we will cement her final crown in place. No one knew that she had broken her tooth except us and anyone she may have told. Although this is a technical and challenging situation, it is highly rewarding when it goes well.
Our patient is an artist, so pays close attention to things like value, hue, chroma, etc. Because of this, and the fact that this is a front tooth, we sent our patient to the dental laboratory that will be making the crown. There, the lab technician can take proper measurements to ensure the shade of the tooth matches. In our patient’s case, it required two separate visits to the lab, because the first version wasn’t quite a match.
The crown material we chose is a lithium disilicate materical called e.max. There are many materials available, and several variations of each material too choose from. In this case we went with a monolithic (single piece) e.max crown. The lab had plenty of space to create the ideal shape, and enough thickness to obtain the proper shade for the tooth.
When crowns are too thin, we need an opaque material to hide the underlying tooth structure, especially if there is any discoloration of the tooth. Other times, when the crown is too thin, we may want a stronger material. In this case, we have plenty of thickness because the remaining tooth structure is rather small, so we can use E.max which is known for being more translucent.
Final Result
Only a few weeks ago our patient walked into the office missing a front tooth. Today, she has a beautiful crown that matches her other front teeth almost perfectly. This tooth has a fighting chance at surviving for a long time. Unfortunately, any tooth that has sustained this much damage has a guarded prognosis, meaning there is a small chance it won’t last five years. But, that was a chance our patient was willing to take.