JOURNAL OF MATERIALS SCIENCE: MATERIALS IN MEDICINE 16 (2 0 0 5 ) 789 – 793 Histological study on sinus lift grafting by Fisiograft and Bio-Oss D. ZAFFE 1, ∗ , G. C. LEGHISSA 2 , J. PRADELLI 3 , A. R. BOTTICELLI 4 1 Department of Anatomy and Histology, Human Anatomy Section, University of Modena and Reggio Emilia, Modena, Italy 2 Associate Dental Office, Milano, Italy 3 Old Age Service, Sassuolo District, Health Agency Local of Modena, Italy 4 Department of Human Pathology, Pathologic Anatomy Section, University of Pavia, Pavia, Italy The work aims to provide a histological investigation of Fisiograft  R , a PLA/PGA copolymer, used as filler for bone defects in humans. The study was performed on biopsies of sinus lifts where Bio-Oss  R and Fisiograft  R gel were applied as graft material. Bone regeneration was satisfactory in all sinus lifts, even when Fisiograft  R was applied alone. Due to remarkable osteoclast activity, Bio-Oss  R granules were cleared from the majority of biopsy cores. At histology, Fisiograft  R gel appeared as globes enveloped by fibroblasts, displaying an epithelial-like cell appearance. Due to its solubility in solvents, undegraded Fisiograft  R (recorded for 7 months or more) did not stain whereas degraded Fisiograft  R stained positive. The loose connective tissue, that surrounded Fisiograft  R and bone contained isolated mastocytes. Bone grew inside the loose connective and often reached the surface of Fisiograft  R by intervening cells. The results seem to indicate that Fisiograft  R may be considered both a polymer useful for fastening bone substitutes inside a defect and in addition a material capable of prompting bone regeneration, with or without the use of a bone substitute. In addition to space-former and space-maintainer functions, Fisiograft  R shows potential bone stimulation function, which may be labelled as osteopromotive capability. C  2005 Springer Science + Business Media, Inc. 1. Introduction Bioresorbable polymers have been widely used as osteosyntesis appliances given their advantages over metallic materials [1]. Appliances made of these poly- mers can fix skeletal segments during the early phases of fracture healing and afterwards degrade sponta- neously, avoiding the need for additional surgery. After the initial enthusiasm for polydioxanone and polyglactin [1], particular attention was has been fo- cused on glycolic acid [2] and lactic acid [3] polymers (PGA & PLA) and their copolymers [4]. The possi- bility of manufacturing biodegradable devices for os- teosynthesis, well tolerated by biological tissues [5], has promoted the diffuse employment of these materi- als in dentistry, maxillofacial and orthopedic surgery. PLA, PGA and copolymers have been installed as mem- branes to perform guided tissue regeneration (GTR) [6] or guided bone regeneration (GBR) [7] in intrao- ral applications. Sponge or spheres of PLA/PGA have been employed as a carrier of rHBMP-2 to stimu- late bone osteogenesis [8, 9]. The capability of tis- sue regeneration by these polymers has been further ∗ Author to whom all correspondence should be addressed. studied using amorphous forms in intraoral districts [10]. Fisiograft  R is a low-molecular-weight PLA/PGA copolymer designed for use in bone grafts as a space filler and maintainer for GTR and GBR treatments. Af- ter the first studies on biocompatibility and bone forma- tion in experimental animals, subsequent reports pub- lished in 1999 [11] have employed Fisiograft  R in hu- mans with satisfactory results [12, 13]. The aim of this work, where Fisiograft  R was used as bone graft to achieve augmentation of the maxil- lary sinus floor (sinus lift) in humans, was to perform histological studies on cellular activities during bone formation in PLA/PGA copolymers, a topic receiving little attention to date. The study was run on undecalci- fied PMMA embedded biopsies using suitable staining to highlight cellular and tissue events. 2. Materials and methods Sixteen patients, males and females ranging from 48 to 64 years of age, underwent monolateral lifting of 0957–4530 C  2005 Springer Science + Business Media, Inc. 789