Cortical Tenting Grafting Technique in the Severely Atrophic Alveolar Ridge for Implant Site Preparation

Abstract

Alveolar ridge augmentation using intraoral autogenous block grafts to augment localized alveolar ridge defects before implant placement is a predictable method. However, large severely atrophic edentulous segments may require extraoral donor sites. The purpose of this study was to evaluate the effectiveness of using intraoral cortical block grafts in combination with particulate human mineralized allograft, in a "tenting" fashion, to augment large atrophic alveolar ridge defects for implant placement. This prospective case study evaluated augmentation in 10 consecutive patients with severely resorbed alveolar ridges missing a minimum of 4 adjacent teeth. Before augmentation, all grafted sites were deemed inadequate for placement of a standard 4-mm-diameter implant. Horizontal ridge augmentation was performed using autologous membranous cortical bone grafts from an oral donor site to tent out the soft tissue matrix and periosteum for the adjacent particulate allograft. The ridges were clinically evaluated 4 to 5 months after augmentation, and 42 implants were placed at that time. Implants were successfully placed at all grafted sites 4 to 5 months after the original graft date. Clinical evaluation of the grafted sites upon re-entry revealed uniform ridge anatomy. All edentulous segments had at least 2 implants placed of at least 4.0 mm diameter. In all, 42 implants were placed into grafted sites in the 10 patients. Implants were checked for osseointegration by using a counter torque of 35 N.cm. One implant failed to integrate. Mean follow-up was 22 months after implant placement. All augmented ridges had retained their functional and esthetic integrity at 1 year after original augmentation. Tenting of the periosteum and soft tissue matrix using a cortical bone block maintains space and minimizes resorption of the particulate allograft volume. In addition, bridging the cortical blocks with particulate bone avoids unaesthetic ridge defects between cortical block grafts in larger ridge defects. The result was a more uniform and esthetic alveolar ridge, capable of maintaining an implant-supported prosthesis. The technique offers predictable functional and esthetic reconstruction of large-volume defects without extensive amounts of autogenous bone. This offers a superior functional and esthetic result than with either cortical or particulate grafting alone.