Working Paper Article Version 1 This version is not peer-reviewed

After Mineralization, Mineralized Freeze-Dried Bone Allograft Particles are Exfoliated but not Resorbed

Version 1 : Received: 23 April 2019 / Approved: 24 April 2019 / Online: 24 April 2019 (12:33:49 CEST)

How to cite: Steiner, G. After Mineralization, Mineralized Freeze-Dried Bone Allograft Particles are Exfoliated but not Resorbed . Preprints 2019, 2019040271 Steiner, G. After Mineralization, Mineralized Freeze-Dried Bone Allograft Particles are Exfoliated but not Resorbed . Preprints 2019, 2019040271


AbstractCadaver bone is possibly the most common transplant material used today. Common types of cadaver bone transplants are freeze-dried bone allografts and xenografts. Studies have shown that mineralized freeze-dried bone allografts have the same percentage of retained bone graft particles at different time points, indicating that these materials are never resorbed. However, it is commonly accepted by clinicians that these materials are resorbed and convert the graft site into normal bone. This histologic study was undertaken to determine the fate of mineralized freeze-dried bone allograft particles grafted into human extraction sockets. Materials and Methods:This study is a photographic, radiologic, and histological analysis of mineralized freeze-dried bone allograft healing in human sockets after mineralization at different time points. The mineralized freeze-dried bone allografts used for evaluation in this study were particulate bone graft materials in maxillary or mandibular extraction sockets. Patient selection was random, based on the following time periods: 6 months, 2 years, 5 years, 7 years, 10 years and 15 years. No block bone grafts were evaluated. Results:No resorption of cadaver bone graft particles was found at any time point. No osteoclasts were found in any of the histology at any time point. At different time points from 6 months through 15 years, mineralized freeze-dried bone allograft particles were found to be exfoliated out of the alveolar crest as a result of the formation of a hypervascular zone surrounding the grafted site. The embedded graft particles remain embedded in sclerotic bone until the particles reach the alveolar crest at which time the sclerotic bone and graft particles break up and are released into the gingiva. All histologic samples from 6 months to 15 years contained residual graft particles. The sclerotic bone formed around graft particles did not integrate to the graft particles or the implant surface. Conclusions:Mineralized freeze-dried bone allograft particles are not resorbed after mineralization. A hypervascular zone forms around the grafted site and exfoliates the bone graft particles into the gingiva. The mineralization process produces sclerotic bone which never remodels into normal bone. Sclerotic bone covers but does not integrate to the retained bone graft particles or implant surface resulting in a weakened structure with an increased likelihood of bone failure and implant loss.


allograft, resorption, sclerotic bone, exfoliation, bone failure



Comments (1)

Comment 1
Received: 3 May 2019
Commenter: Kevin R Hansen DDS
The commenter has declared there is no conflict of interests.
Comment: During the years of reviewing the histological studies of Dr. Steiner, and having reviewed bone remodeling and maturation, it is becoming more obvious to me that our implementation of proper bone grafting is one of the greatest services we can provide our patients. Both short-term and long-term implant stability and health are goal of every clinician doing bone grafting and/or implant placement. Dr Steiner's desire to provide extremely reliable research, and commit so much time in research at the cellular level is admirable. I find such evidence-based research hard to dismiss as insignificant, and in fact is having significant influence on my success in every implant I place and every bone graft I perform.
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