We can understand Dr. Trester’s concern relating to the possibility that "at least 30 percent of the teeth in the control group likely had undiagnosed caries into the dentin." We too were concerned at the conclusion of the baseline treatment of those teeth randomized into the experimental group. We then expected to find a much higher percentage of caries than we originally thought in the control teeth due to the reasoning noted by Dr. Trester.
Also, by probing the teeth extensively, as in this study by two dentists independently, any decalcified enamel would be destroyed and thus eliminate the chance of remineralization.1,2 In addition, there is a chance to transmit cariogenic bacteria on the tip of the dental explorer from one tooth to another. All of these factors should increase the chance of caries in the control teeth even more, and this was the anticipated hypothesis for the study.
Surprisingly, a number of factors have not supported these concerns. We now have completed our three-year recalls and are currently conducting 48-month recalls. We have seen no significant change in the mean size of preparations in control teeth; the number of control teeth showing signs of decay is still less than expected; no patient has experienced any pre- or post-operative sensitivity associated with any teeth or restorations enrolled in the randomized clinical trial; and there is no significant difference between the two groups when one examines the need for anesthesia to prepare these teeth with early caries.
Consequently, we are starting to question whether the caries discovered in dentin in 44 percent of the experimental teeth is progressing, regressing or just arrested caries. Remember that, due to all of the factors noted in the first paragraph, we should see more and larger carious lesions than expected. If one feels that the explorer is a poor tool for diagnosing caries, the implication is that the caries diagnosed with an explorer in control teeth would be further advanced when discovered, leading to a larger preparation size. We have not seen a significant difference between the sizes of the preparations in the two groups.
Dr. Trester commented, "No mention was made of the fact that carious surfaces can recalcify while actively carious beneath hard surface enamel." We believe that this refers to a condition often referred to as hidden caries,3 or occult caries4 or fluoride syndrome.5
A possible theory as to why we have not seen this condition relates to the probing by two independent dentists. This would eliminate the chance that the enamel portion of these carious lesions would recalcify and thus expose the underlying dentin and possibly allow the dentin to remineralize. We realize this is probably the first time anyone has ever posed the possibility that caries into dentin in a pit or fissure of a posterior tooth may remineralize. We were all taught that this condition requires operative intervention.
We regret that this response does not allow us to show photographic evidence of the above phenomenon. Over a period of 48 months, a questionable carious lesion in the distal pit of a maxillary first molar control tooth has progressed to a hard and smooth defect that, for the last 18 months, has recorded consistently around 15 on the DIAGNOdent scale. This would be a good candidate for sealing, but since sealing is not in the protocol for this randomized, controlled clinical trial, we continue to observe it.
Concerning Dr. Trester’s question as to "why additional sophisticated, objective, studied and reliable diagnostic devices, such as DIAGNOdent, were not used in this study," this device was not available in the United States when this study started in December 1997. Once the unit was available in the United States, Kavo loaned us a unit to use in our clinical research. Since that time, we have recorded DIAGNOdent readings on all control teeth at each recall examination after they have been evaluated independently by two clinicians so as not to bias the evaluators’ caries evaluation.
Consistency of DIAGNOdent readings and trends in readings over 18 months will be presented at the International Association for Dental Research Annual Meeting in Göteborg, Sweden, June 2003, and the 50th ORCA (European Organization for Caries Research) Congress in Konstanz, Germany, July 2003.
Dr. Trester voices concern about allowing minimally decayed teeth that have caries into dentin to go "undiagnosed and therefore untreated." The treatment of minimal caries involves some risk of treating caries that have not penetrated into dentin and may never need treatment (56 percent in this study), plus the long-term maintenance of the resultant restoration. What we have found in our clinical study after more than three years is that, if an error is made in not treating caries into dentin, the consequences are that the preparations are no larger, fewer restorations are placed, no pre-or post-operative sensitivity exists and there is no greater need for local anesthetic than in the early treatment group.
Concerning Delta Dental Fund of Michigan having a financial interest in the use of the data outcome: this is no different from research funded by drug companies or dental manufacturers. Once the study started in December 1997, there were no comments or suggestions of any kind from Delta Dental Fund of Michigan. We find this in stark contrast to the interest shown by dental manufacturers, who want all the data and reports by yesterday and in some cases, want to see manuscripts prior to publication.
Our data cannot support Dr. Trester’s comment that "the cost of undiagnosed caries can increase the cost of restoration by 10 to 20 times." The trends in DIAGNOdent readings over 18 months, although not statistically significant, will probably surprise Dr. Trester and others who would think that questionable carious lesions would progress with time. Our study and DIAGNOdent readings do not support that assumption at this time.
We appreciate Dr. Trester’s interest in this very important question, which has been asked before in different ways. When should a dentist operatively intervene into an incipient carious lesion?
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