Biological invasions at the gene level

Despite several recent contributions of population and evolutionary biology to the rapidly developing field of invasion biology, integration is far from perfect. I argue here that invasion and native status are sometimes best discussed at the level of the gene rather than at the level of the species. This, and the need to consider both natural (e.g. postglacial) and human-induced invasions, suggests that a more integrative view of invasion biology is require

Effect of absorbable membranes on sandwich bone augmentation

Objectives : This study was conducted to evaluate the effect of barrier membranes on sandwich bone augmentation (SBA) for the treatment of implant dehiscence defects. Material and methods : Twenty-six implant-associated buccal dehiscence defects in 22 patients were treated according to the SBA concept – mineralized human cancellous allograft (inner layer), mineralized human cortical allograft (outer layer) and coverage with barrier membrane. The defects were randomly assigned to the bovine collagen membrane (BME) group; acellular dermal matrix (ADM) group; and no membrane group. Measurements at baseline and 6 months re-entry included defect height (DH: from smooth–rough junction to the most apical part of the defect), defect width (DW: at the widest part of the defect), and horizontal defect depth (HDD: at three locations – smooth–rough junction, middle, and most apical portion of the defect). All measurements were taken from a reference stent. Statistical analyses were performed for comparison of intra- and inter-group comparisons. Results : All implants placed were successfully osseointegrated. DH at baseline for three groups were not significantly different ( P =0.858). Mean % DH reductions for ADM, BME, and control groups at 6 months were 73.9±17.6%, 68.1±30.1%, and 63.6±23.9%, respectively, with no significant difference among the groups ( P =0.686). Mean horizontal bone gain, however, was significantly greater for membrane groups (1.7 mm for ADM, 1.6 mm for BME) compared with control group (1 mm) ( P =0.044). Implant exposure resulted in significant reduction in total height gain (79.1±14.3% vs. 57±23.5%, P =0.021). Conclusions : Within the limit of this study, it is concluded that SBA technique achieved predictable clinical outcomes. The addition of absorbable membranes enhanced bone gain in thickness compared with membrane-treated sites. To cite this article: Park S-H, Lee K-w, Oh T-J, Misch CE, Shotwell J, Wang H-L. Effect of absorbable membranes on sandwich bone augmentation. Clin. Oral Impl. Res . 19 , 2008; 32–41. doi: 10.1111/j.1600-0501.2007.01408.xPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74133/1/j.1600-0501.2007.01408.x.pd