In our article, the efficacy of subantimicrobial dose doxycycline, or SDD, as an adjunct to scaling and root planing was discussed. Ten different issues of importance to clinicians were debated, employing a point/counterpoint format to provide clinicians a discussion of the advantages and limitations of this treatment modality.
Our assessment suggests that clinicians need to differentiate between statistically and clinically significant results when selecting treatment methods. It also was mentioned that clinicians should focus on reducing the bacterial challenge prior to attempting to alter the host response. In this regard, it was stated that repeat root planing or administration of an appropriate antibiotic may preclude the need to administer SDD.
Regrettably, Dr. Golub in his letter did not address the 10 different issues debated in the article concerning the merits of SDD. Instead, he focused on one study that was added to the article as an addendum after the commentary was accepted for publication.
Dr. Golub states that we made errors in reporting facts and interpreting data. However, he did not delineate any mistakes. We would have been happy to address all issues that he raised about the text of the article.
The study by Golub and colleagues1 was included in the addendum entitled "Update: An Additional Clinical Trial" to provide clinicians insight into a recent article concerned with SDD utilization in the treatment of chronic periodontitis. As Dr. Golub indicated, an inclusion criterion for patients to participate in their study was the presence of two to three pockets that demonstrated increased collagenase levels in the gingival crevicular fluid. It is true that the results of his investigation were reported without discussing his methods and materials. However, we did not address the methods and materials of any other articles in the commentary.
Regarding the investigation by Golub and colleagues,1 we believe that our interpretation of the data is accurate, and the study protocol did not change our perception of the investigation’s clinical relevance. The finding that twice-per-day administration of SDD results in a 0.3 millimeter gain of clinical attachment vs. none for the placebo group after 12 weeks may be statistically significant, but its clinical relevance is questionable.
Furthermore, the results at week 36 (after two scaling visits, at baseline and week 24), which indicated that the placebo group lost 0.8 mm and the test group receiving SDD plus scaling lost 0.15 mm of clinical attachment, were also questioned because it was surprising that both groups deteriorated. This possibly was due to the fact that only 30 minutes was allocated for scaling patients diagnosed as having periodontitis. Or maybe root planing should have been performed as opposed to scaling.
It was stated—and we still believe—that continued loss of clinical attachment, despite two episodes of mechanical instrumentation, is contradictory to what is usually reported in the dental literature. In addition, the nine-month-long phase 3 clinical trial that was pivotal in attaining U.S. Food and Drug Administration approval for SDD also indicated that root planing without SDD routinely resulted in a gain of clinical attachment.2
Dr. Golub emphasizes that assessment of collagenase levels at specific sites prior to therapy may help select sites predisposed to continued breakdown, and these locations may be more responsive to SDD therapy. There may be some validity to this point. However, collagenase levels have never been proven to be a reliable indicator of future disease progression.
In addition, there are no commercially available assays to assess collagenase levels at chair-side; therefore, clinicians cannot delineate sites with increased amounts of collagenase. Also, we are unaware of any data to support the contention that in the presence of elevated collagenase levels, root instrumentation is ineffective in the treatment of periodontitis.
In summary, we did not misunderstand the clinical trial conducted by Dr. Golub and colleagues.1 Rather, we interpreted it with respect to its clinical relevance. Accordingly, it was concluded that clinicians should evaluate the results cautiously because the data could be interpreted erroneously to mean that if elevated collagenase levels were recorded, failure to administer SDD results in continued loss of clinical attachment, even when root instrumentation was performed.
In addition, it was stated in the commentary that the adjunctive use of SDD might be beneficial in patients who are nonresponsive to conventional therapy. However this needs to be validated in controlled clinical trials.
In conclusion, we have concerns regarding the way SDD is administered to the general population. Specifically, we disagree with the concept that SDD should be routinely used as an adjunct to scaling and root planing in the treatment of chronic periodontitis. Therefore, let us work together to elucidate the best way to treat chronic periodontitis, a disease that is recalcitrant to conventional therapy in a limited number of patients.
Furthermore, additional data should be carefully accrued to define the relationship between periodontitis and other systemic diseases or problems before clinicians rationalize adjunctive use of SDD to prevent possible, but unproven, sequelae of periodontitis.
It should be noted that, at present, there are only association data between periodontitis and several systemic diseases. Therefore, without intervention studies to validate a cause-and-effect relationship, dentists should be careful not to misinterpret available information to suggest that periodontal therapy with or without SDD can prevent the development of specific systemic diseases.
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