VERTICAL RIDGE AUGMENTATION AROUND DENTAL IMPLANTS USING A MEMBRANE TECHNIQUE AND AUTOGENOUS BONE OR ALLOGRAFTS IN HUMANS

This study investigated the effect on vertical bone regeneration of th e addition of demineralized freeze-dried bone allograft or autogenous bone chips to a membrane technique. Twenty partially edentulous patien ts with vertical jawbone deficiencies were selected for this study The patients were divided into two groups of 10 individuals. The 10 patie nts of Group A received 26 Branemark implants in 10 surgical sites. Th e TO patients of Group B received 32 implants in 12 surgical sites. Fi fty-two out of 58 implants (22 in Group A and 30 in Group B) extended 1.5 to 7.5 mm superior iio the bone crest. Titanium-reinforced expande d polytetrafluoroethylene membranes were used to cover the implants an d, before complete membrane fixation, demineralized freeze-dried bone allograft particles were condensed under the membrane in Group A, and autogenous bone chips were used in Group B. At the reentry after 7 to 11 months the membranes were removed and a small biopsy was collected from 11 sites comprehending the miniscrews. The clinical measurements from Group A demonstrated a mean vertical bone gain of 3.1 mm (SD = 0. 9 mm, range 1 to 5 mm) with a mean percentage of bone gain of 124% (SD = 46.6%). The measurements from Group B showed a mean vertical bone g ain of 5.02 mm (SD = 2.3 mm, range 1 to 8.5 mm) with a mean percentage of bone gain of 95% (SD = 26.8%). Histomorphometric analysis of the p resent study clearly demonstrated a direct correlation between the den sity of the pre-existing bone and the density of the regenerated bone. The mean percentage of new bone-titanium contact was from 39.1% to 63 .2% depending on the quality of the pre-existing bone. Both the clinic al and histologic results indicate a beneficial effect of the addition of demineralized freeze-dried bone allograft or autogenous bone parti cles to vertical ridge augmentation procedures in humans.