Composite block sponge proved facilitating bone augmentation

VEGVX ePOSTER CLINICAL INNOVATIONS

Background: Guided Bone Regeneration (GBR) is considered sufficient in alveolar ridge deficiencies. Block type grafts and/or particulate materials combined with membrane for secluding space are the backbone of the principle. Block grafts belong either to autogenous or allogenic biomaterials. Newly introduced composite graft out of porcine sugar cross-linked collagen type 1 and synthetic hydroxyapatite (SCLC+HA; Ossix^™Bone, Regedent, Dettelabach, Germany) used as alternative material for extraction sockets.

Aim/Hypothesis: Case series evaluated feasibility of newly introduced composite spongy graft enhancing bone formation in three clinical indications using radiography, ex vivo human histology and immunohistochemistry (IHC). Allocated indications included lateral + vertical ridge augmentation and sinus grafting.

Materials and Methods: Full-thickness flap elevation denudated the bony ridge, cortical plate was perforated by round bur to promote bleeding. Composite sponge was adapted to exposed defect surface once its rehydration with patient's blood completed. Porcine ribose cross-linked collagen membrane (Ossix^®Plus, Regedent, Dettelbach, Germany) secluded soft tissue flap from contacting sponge and stabilized graft as NOe additional fixation was intended. Tensionless flap closure was achieved by coronal advancing the flap releasing the periosteum. Suture removal followed at day 7 to 10; bone formation lasted for 6-8 months. Periapical x-rays and CBCT scans documented change in ridge dimension indicating new bone formation. Full-thickness flaps were reflected, core biopsies retrieved by hollow cylINDIAr drill at osteotomy for implant installation. Biopsies were forwarded in 4% formalin for decalcified processing and routine staining. Paraffin sections were stained with H.E.; Masson-Goldner; PAS; TRAP and IHC.

Results: Three patients and 4 single gaps in the anterior maxilla and one edentulous posterior mandible missing second premolar and first molar were treated for lateral augmentation. One single gap vertical augmentation in a maxillary premolar and one sinus grafting by lateral window with residual bone height of 3 to 4 mm were included. Radiographically estimated ridge changes ranged from 3.5 mm to 5 mm in numbers regardless allocation of treatment area to anterior maxilla or posterior mandible but exceeding 5 mm in height following sinus floor elevation. Core biopsies revealed newly trabecular bone with high numbers of active osteoblasts; active osteoclasts densely adhered to the HA particles within composite block residues; focally occurring bone formation process within the body of composite block; lamellar bone in the crestal zone of the mandibular biopsy and in the crestal portion of the biopsy from vertical augmentation. Specimen from sinus graft showed new bone without residues of the graft.

Conclusions and Clinical Implications: Use of composite SCLC+HA graft together with the RCLC membrane regularly facilitated formation of new bone within the body of the sponges as corroborated by clinical and microscopic observations. The defect allocation, i.e. maxillary or mandibular either anterior or posterior bone deficiency had NOe impact on the outcome. We conclude that composite SCLC+HA sponges were feasible to use in combination with RCLC membranes for bone augmentation in a staged approach.

Keywords: ridge augmentation, GBR, sugar cross-linked collagen sponge, bone formation, human histology