Friedmann A, Gissel K, Soudan M, Kleber B-M, Pitaru S, Dietrich T. Randomized controlled trial on lateral augmentation using two collagen membranes: morphometric results on mineralized tissue compound. J Clin Peridontol 2011; doi: 10.1111/j.1600-051X.2011.01738.x. ABSTRACT: Background: Guided bone regeneration is considered an effective tool for gaining mineralized tissue either at exposed implant surface or in deficient alveolar ridge areas before implant placement. Material and methods: Customized casts obtained following impression taking at surgery and re-entry allowed for morphometric assessment of alveolar ridge alterations 6 months after one-stage augmentation of bone dehiscences. In a randomized pilot study using biphasic calcium phosphate tests (n=17) received treatment with ribose cross-linked collagen membranes (RCLM), whereas controls (n=20) received non-cross-linked membranes. The primary endpoint was to quantify the effect of membrane type on dimensional changes in bone margins at crestal level of endosseous implants. Results: Soft tissue dehiscencies occurred at 70.5% and 55% frequency for tests and controls, respectively. Gain in clinically hard newly mineralized tissue at the crestal level was significantly higher in test group in lateral (1.8 versus 0.7 mm; p=.046) and in vertical dimensions (1.1 versus 0.2 mm; p=.035) compared with controls. Second measurement obtained at the border of reflected flap revealed no significant difference between groups (3.0 versus 2.1 mm; p=0.57) for lateral dimension. Conclusions: Both collagen devices were effective in bone augmentation. RCLMs supported mineralization process and remodelling even in sites showing compromised healing as indicated by morphometric outcome.