Researchers from the Universitat Politècnica de Catalunya (UPC) and Mimetis Biomaterials, together with implantologist Dr. Ignacio Ginebreda (UIC Barcelona), have compared a biomimetic synthetic calcium phosphate graft with a deproteinised bovine xenograft in standardised three-wall alveolar defects, one of the most common situations in implant dentistry. The study was published in Clinical Oral Investigations and conducted at Versa Biomedical’s facilities in Barcelona (then Specipig). It is one of the 15 preclinical dental studies Versa Biomedical has carried out on dental implants and bone graft regeneration biomaterials. Download case

About the study:

Purpose

When a tooth is lost and an implant is not placed promptly, the alveolar ridge resorbs, often leaving too little bone to anchor an implant. Bone grafting is the standard solution, and its clinical success depends on preserving the grafted volume while the graft is remodelled into new bone. The study set out to compare a biomimetic synthetic graft, processed at low temperature to resemble the mineral phase of bone, with a long-established xenograft, in terms of volume preservation and tissue response.

Methods

Eight Specipig miniature pigs each received eight standardised three-wall defects, 12 mm deep and 10 mm wide. The defects were created in both jaws after tooth extraction by removing half of the buccal bone plate. In each animal, three defects were filled with the synthetic graft, three with the xenograft, and two were left empty as negative controls, in a randomised and balanced allocation. All defects were covered with a resorbable collagen membrane. Four animals were evaluated at 6 weeks and four at 12 weeks, giving 12 replicates per material and time point. Grafted volume was measured by spiral CT one day after surgery and at the endpoint, and analysed with a linear mixed-effects model. Tissue response was assessed in undecalcified samples by backscattered scanning electron microscopy and by light microscopy after Masson’s trichrome staining. All surgeries were performed by Dr. Ginebreda.

Results

Empty defects showed no bone regeneration, which confirmed that the model was critically sized. Graft type was the most influential factor, and the synthetic graft preserved about 19% more volume than the xenograft. At 6 weeks, the synthetic graft had lost around 11% of its initial volume and the xenograft around 31%. At 12 weeks, the synthetic graft had gained around 6%, while the xenograft remained about 15% below its initial volume. Anterior sites preserved volume better than posterior ones, and volume improved between 6 and 12 weeks. Whether a defect was in the maxilla or the mandible had no significant effect. Histology showed excellent biocompatibility for both materials, with no inflammation or necrosis. New bone grew in direct contact with the granules, and mature bone with Haversian structure was already present at 6 weeks. Concavities in the synthetic granules were associated with osteoclastic resorption, a sign that the material was taking part in normal bone remodelling.

Conclusions

Both biomaterials met the requirements for bone grafting: biocompatibility, osseointegration and osteoconduction. The synthetic graft showed better volume preservation, and granule morphology was identified as an important factor in it. The study also shows what a well-designed miniature pig alveolar model can deliver: a critical-size defect, enough statistical power to tell products and anatomical effects apart, and readouts aligned with how clinicians follow grafted sites in their patients.

Keywords

Implant dentistry; Bone regeneration; Bone graft; Xenograft; Synthetic graft; Alveolar defect; Miniature pig.