GTR has a greater effect on probing measures of periodontal treatment than open flap debridement, including improved attachment gain, reduced pocket depth, less increase in gingival recession and more gain in hard tissue probing at re-entry surgery. However there is marked variability between studies and the clinical relevance of these changes is unknown. As a result, it is difficult to draw general conclusions about the clinical benefit of GTR. Whilst there is evidence that GTR can demonstrate a significant improvement over conventional open flap surgery, the factors affecting outcomes are unclear from the literature and these might include study conduct issues such as bias. Therefore, patients and health professionals need to consider the predictability of the technique compared with other methods of treatment before making final decisions on use. Since trial reports were often incomplete, we recommend that future trials should follow the CONSORT statement both in their conduct and reporting. 
There is therefore little value in future research repeating simple, small efficacy studies. The priority should be to identify factors associated with improved outcomes as well as investigating outcomes relevant to patients. Types of research might include large observational studies to generate hypotheses for testing in clinical trials, qualitative studies on patient-centred outcomes and trials exploring innovative analytic methods such as multilevel modelling. Open flap surgery should remain the control comparison in these studies.
Enamel matrix proteins and guided tissue regeneration with titanium-reinforced expanded polytetrafluoroethylene membranes in the treatment of infrabony defects: a comparative controlled clinical trial.
Several studies have documented the clinical efficacy of guided tissue regeneration (GTR) with non-resorbable expanded polytetrafluoroethylene (ePTFE) membranes and enamel matrix proteins (EMP) in the treatment of infrabony defects. The objective of this controlled clinical study was to compare the clinical outcomes of 3 surgical modalities in the treatment of deep interproximal infrabony defects.
                Ninety (90) defects in 90 healthy subjects affected by chronic periodontitis were assigned to 1 of 3 treatment groups by blocking to prognostic variables. The test group was treated with the application of EMP and the simplified papilla preservation (SPP) technique; the second group was treated with titanium-reinforced ePFTE membranes and the SPP technique; and the third group was treated with the SPP technique used as access flap control procedure. No differences were observed in terms of baseline oral hygiene and defect characteristics among the 3 groups, indicating that the blocking approach was effective. A stringent infection control program was adopted for 1 year.
                The 1-year results indicated that: 1) all treatment modalities resulted in clinically significant improvements in clinical attachment levels (CAL) and reduction in probing depth (PD); 2) a statistically significant treatment effect was demonstrated comparing the EMP test, the membrane control, and the flap control groups in terms of CAL gains; 3) both the EMP test and the membrane control groups showed significant CAL gains compared to the flap control group; 4) a statistically significantly greater amount of CAL gain was demonstrated in GTR-treated compared to EMP-treated patients; 5) deeper residual probing depths but smaller increases in gingival recession were demonstrated following EMP therapy; and 6) smoking habits reduced the clinical outcomes of both regenerative procedures.
                The use of a regenerative procedure is indicated in the treatment of deep vertical bony defects since both the regenerative techniques (GTR and EMD) in the present study resulted in clinically and statistically significant improvements in clinical parameters compared to the access flap procedure. The use of EMP can be helpful in esthetically-sensitive sites and in reducing patient morbidity.