Elliot Abt DDS, MSc, MS
Enamel matrix derivative (EMD) significantly improved both periodontal attachment levels (1.1mm) and pocket depth reduction (0.9mm) when compared to placebo, open-flap debridement, guided tissue regeneration (GTR), or bone grafting procedures.
Although this high-quality review found statistically significant improvements when comparing EMD with other methods of periodontal therapy, caution should be applied when interpreting these results as bias among included studies may have exaggerated treatment effects.
In patients with intrabony pockets, is EMD more effective than placebo, open-flap surgery, GTR, or bone grafting procedures?
Four databases, up to February 2009, were searched by two reviewers for randomized controlled trials comparing EMD to other periodontal regenerative procedures for intrabony defects of at least 3mm. Outcomes included tooth loss, esthetics, complications, probing attachment level, pocket depth, gingival recession, and changes in alveolar bone level.
Of 35 potentially eligible studies, 13 trials, involving 653 patients, met the inclusion criteria for the review. A meta-analysis of 9 trials showed that EMD sites had a statistically significant improvement in attachment level of 1.1mm (95% CI 0.61-1.55) and a reduction in pocket depth of 0.9mm (95% CI 0.44-1.31) when compared to the placebo or control treated sites. Approximately 9 patients have to be treated (NNT=9) with EMD for one patient to gain 2mm or more of clinical attachment over the control group. There was no difference between EMD and control groups with respect to tooth loss or esthetics.
While EMD had statistically significant benefits when compared with placebo or other periodontal therapies, several issues exist with interpreting these results. There was significant heterogeneity among included studies, and bias may have overestimated treatment effects. With the exception of fewer complications as compared to GTR, the clinical effects of EMD on disease management and tooth loss are unknown.
Source of Funding:
School of Dentistry, The University of Manchester, UK
Importance and Context:
Periodontitis is a chronic inflammatory/infectious process of the supporting structures of the teeth which can ultimately lead to tooth loss. One of the difficulties with disease management has been with regeneration of lost periodontal tissues to alleviate potential sequelae such as gingival recession, root sensitivity, and esthetic concerns. Currently, there are several therapies now available for this process, including grafting, guided tissue regeneration, and the use of EMD. Both practitioners and patients could benefit from evidence demonstrating the superiority of one of these therapies.
Strengths and Weaknesses of the Systematic Review:
This high-quality review began with a focused clinical question, a comprehensive search for trials meeting the inclusion criteria, and double (independent) data extraction by two of the authors. In the review, authors also hand-searched several journals and contacted experts for any other published or un-published studies, without language restriction, for studies meeting the inclusion criteria. A detailed list of all included and excluded studies was provided along with an impressive list of the characteristics of included studies. A thorough risk of bias table was provided, and authors of included trials were contacted for clarification regarding dimensions of trial quality such as randomization and blinding. Tests for heterogeneity were done to assess the appropriateness of combining studies in a meta-analysis. A sub-group analysis for split-mouth and parallel group trials was performed along with a sensitivity analysis examining the robustness of the evidence from trials at low risk of bias. An examination of publication bias was also planned, but not addressed.
Strengths and Weaknesses of the Evidence:
Roughly half as many sites in control groups had less than a 2mm gain in clinical attachment as compared with EMD (RR 0.53 95% CI 0.34-0.82; NNT=9). However, the results from the sub-group analysis showed that the effects of EMD versus control groups were smaller for split-mouth trials. That is, the increase in attachment level with split-mouth trials was only 0.76mm (95%CI 0.48-1.04). Similarly, probing depth with split-mouth trials was 0.66mm (95%CI 0.31-1.00). When only trials at low risk of bias were analyzed (sensitivity analysis), summary estimates for attachment level and pocket depth were even smaller. Additionally, there was considerable heterogeneity among all trials with respect to these two parameters, possibly due to clinical and/or methodological differences between parallel group studies. Therefore, the overall summary effect estimates appear to be exaggerated, and are likely smaller than reported.
Implications for Dental Practice:
Although the review found significant results for the effects of EMD versus control groups after one year, practitioners should use discretion when interpreting these results. Trials at low risk of bias found attachment level gain and pocket depth reduction of 0.62 and 0.60mm, respectively. It is arguable that a gain in attachment or a reduction in pocket depth of less than 1mm may be a clinically insignificant finding of a surrogate outcome, as the long-term effects of EMD on tooth loss, esthetics, or quality of life are currently unknown. However, EMD may be an attractive alternative to other regenerative methods due to its handling characteristics and relatively few post-operative complications.