In a 1998 review article, Laurell and colleagues performed a meta-analysis of relevant guided tissue regeneration (GTR) articles over the previous 20 years (1). The purpose of the present research was to expand on that work, particularly searching for trends discriminating between bioabsorbable and non-bioabsorbable barriers, as well as the use of enamel matrix derivative, with respect to interproximal bony defects. The most recent periodontal journals were reviewed and a search of PubMed (National Institutes of Health) was conducted via the internet covering 1990 to the present. Forty-nine articles were found to be relevant and within established parameters. The data were analyzed using (a) a variation of the methods described in Laurell et al. (1) and (b) statistics appropriate for inter-group comparisons. In most respects, all membranes and enamel matrix derivative (EMD) delivered better outcomes, in the range of 1 to 2 mm, than open flap debridement. The use of any barrier type or EMD configuration was found to yield more Clinical Attachment Level (CAL) gain than any open flap configuration. Other than collagen without grafts versus non-bioabsorbables without grafts, no other comparison between membranes or between membranes and EMD found any significant differences (P > 0.05). GTR was confirmed to be superior to open flap debridement. (J Oral Sci 51, 383-400, 2009)