I was excited to see Dr. James Bader and colleagues’ article, "Risk Indicators for Posterior Tooth Fracture," in July JADA. The practicing dentist has had very little scientific data on which to make restorative decisions or data to help a patient understand the percentage of risk involved in making a particular decision. Thank you to the authors, and to JADA, for this important first step in this direction.
While not scientific, I want to offer what I feel are important observations in this area. First, a bit about my background. I have always maintained a fee-for-service practice. I placed my first posterior occlusal resin-based composite in 1970, using Nuva Fill. With increased skills and improved materials, I was placing a higher percentage of resin-based composites with time.
By 1986, due to a lack of patient demand, I had discontinued the use of amalgam. While most of the amalgam restorations I placed were placed under a rubber dam, many were without. Almost all composites were placed under a rubber dam.
I am finding a very high, long-term success rate with the direct resin-bonded composites I have placed. There is a low incidence of recurrent caries, sensitivity, cusp fracture or development of incomplete fracture lines (cracks). I have had difficulty obtaining contact areas I liked, but with the techniques I now use, my contact areas are so tight the problem is sometimes I have difficulty getting the floss through.
My observations are as follows:
- I have seen very few cusp fractures where the first restoration placed in the tooth was a direct resin-based composite, no matter what the size of the restoration. I have seen small enamel fractures on the occlusal margin of molars with wide restorations. Sometimes these can be conservatively restored; sometimes resultant caries or thinness of the remaining tooth has mandated a crown at that time.
- I do not recall ever seeing a tactilely detectable fracture line occur in a tooth initially restored with a direct resin-based composite, no matter what the size of the restoration.
- Any research efforts to compare the difference between cusp fractures of teeth restored with direct resin-bonded composite or amalgam should divide the composite-restored teeth into two groups. One group would be those teeth initially restored with composite. The second group would be those teeth initially restored with amalgam, and then later restored with direct resin-bonded composite. The results of these two groups would be different.
- Notes in my charts and observations tell me that, when an amalgam restoration is removed from a tooth and incomplete fracture lines are observed in the cavity with loupes, the teeth can be divided into the following risk groups:
- Small vertical cracks in the enamel only, which cannot be felt with an explorer: a smaller risk of developing a fracture, unless there is a cusp so thin you can almost read through it, and it has cracks on each side of the cusp.
- Vertical cracks, undetectable with the explorer, on either side of a cusp, with a connecting light-colored horizontal crack at the base of the cusp: a greater risk of fracture. If the horizontal crack is a darker-colored crack, the risk of developing a fracture is increased.
- Item b, with explorer-detectable vertical cracks: a very high risk of developing a fracture.
- Mesial and distal enamel cracks, connected with a light-colored horizontal crack in the center of the pulpal wall: a risk of developing a fracture. e. Item d, with a larger horizontal, black-colored crack on the pulpal wall: a much larger risk of developing a fracture, and also a good risk of later needing endodontic care. If this tooth is not crowned and later fractures, it has a high risk of not being restorable. Though unlikely, it can fracture, even if it is crowned.
I see a greater incidence of these incomplete fracture lines (cracks) and cusp fractures in teeth I restored with amalgam without a rubber dam than in teeth I restored with amalgam under a rubber dam. I often can tell the difference between amalgam restorations I placed under a rubber dam or without a rubber dam before I read the chart notes.
I hope future scientific studies can explore the issues I have mentioned.
