Tomodensitometric and histologic evaluation of the combined use of a collagen membrane and a hydroxyapatite spacer for guided bone regeneration: A clinical report

In this report, the problems of insufficient bone and soil tissue after ext raction of maxillary incisors were addressed concurrently prior to endosseo us implant placement, by combining the use of a diphenylphosphorylazide-cro ss-linked Type I collagen membrane and a resorbable space-making biomateria l composed of 200-mu m porous hydroxyapatite granules blended in Type I col lagen and chondroitin-4-sulfate. Upon flap reflection 8 months postsurgery, the horizontal deficiencies were almost completely resolved, membranes com pletely resorbed and the defects filled with hard, bonelike tissue, with a few superficial hydroxyapatite granules. Histologic evaluation of the bone biopsies obtained at the implantation sites revealed dense, well-reconstruc ted alveolar bone with a few traces of hydroxyapatite granules that had bee n completely resorbed. Tomodensitometric evaluation indicated that bone reg eneration ranged from 14% to 58%, with an average bone gain of 29.77%. Four nonsubmerged ITI titanium implants placed in the augmented bone have been in function for more than 5 years, with no clinical or radiographic signs o f hard or soft tissue breakdown. Bacterial sampling at dental sites with pe riodontitis 1 month prior to periodontal therapy and at implant sites for u p to 30 months demonstrated rapid colonization of implant surfaces by perio dontopathogens without causing any detrimental effect to implant integratio n.