D. Dohan

Chonnam National University, Gwangju, Gwangju, South Korea

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Publications (40)15.71 Total impact

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    ABSTRACT: We recently published in Muscles Ligaments and Tendons Journal a classification of platelet concentrates (commonly termed Platelet-Rich Plasma-PRP or Platelet-Rich Fibrin-PRF) for topical and infiltra-tive use in orthopedic and sports medicine 1 , based on previous research works and consensus articles developed by several experts in the field in various clinical disciplines 2-4. Following the publication of our article, Anitua et al. submitted a letter to the Editor, complaining that they were not cited enough and about the way the technique , commercially termed PRGF ® (Plasma/Prepa-ration Rich in Growth Factors) or Endoret ® , had been described shortly in our independent classification review article. In the form and in the content, these authors are aggressively attacking our scientific credibility. We will answer in a point by point fashion to their letter. We thank Prof. Nicola Maffulli and the Editorial Board of Muscles Ligaments and Tendons Journal to have allowed us to reply to Anitua et al.'s letter.
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    ABSTRACT: The PACT (Platelet & Advanced Cell therapies) Forum Civitatis of the POSEIDO was created to offer a multidisciplinary platform of research, publication, debates and eventually consensus for researchers in the fields of Tissue Engineering and Regenerative Medicine (TERM). In this review, the issues, endeavors and perspectives of this considerable research field are discussed and illustrated, particularly (but not only) through the example of the history, failures and success of probably the oldest method developed in regenerative medicine, the topical use of autologous platelet concentrates (commonly known as Platelet-Rich Plasma – PRP or Platelet-Rich Fibrin – PRF). The History of this domain illustrates very well that the greatest enemy of knowledge is not ignorance; it is the illusion of knowledge. Fighting against illusions in Sciences is a very complex and tricky task, requiring continuing efforts and time. This PACT for a transdisciplinary, translational and international approach in regenerative medicine is an important step in this endeavor.
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    ABSTRACT: Background and Objectives. Platelet concentrates for surgical use (Platelet-Rich Plasma PRP or Platelet-rich fibrin PRF) are surgical adjuvants to improve healing and promote tissue regeneration. L-PRF (Leukocyte-and Platelet-Rich Fibrin) is one of the 4 families of platelet concentrates for surgical use and is widely used in oral and maxillofacial regenerative therapies. The objective of this second article was to evaluate the impact of the centrifuge characteristics (vibration intensity) on the cell and fibrin architecture of a L-PRF clot and membrane. Materials and Methods. Four different commercially available centrifuges were used to produce L-PRF, following the original L-PRF production method widely described in the literature (glass-coated plastic tubes, 400g force, 12 minutes). The tested systems were the original L-PRF centrifuge (Intra-Spin, Intra-Lock, the only CE and FDA cleared system for the preparation of L-PRF) and 3 other laboratory centrifuges (not CE/FDA cleared for L-PRF): A-PRF 12 (Advanced PRF, Process), LW-UPD8 (LW Scientific) and Salvin 1310 (Salvin Dental). All clots and membranes were collected into a sterile adequate surgical box (Xpression kit). The exact macroscopic (weights, sizes) and microscopic (photonic and scanning electron microscopy SEM) characteristics and the cell composition of the L-PRF clots and membranes produced with these 4 different machines with 4 different vibration intensity levels were evaluated. Results. Intra-Spin showed the lowest temperature of the tubes. A-PRF and Salvin were both associated with a significant increase of temperature in the tube. Intra-Spin produced 142 Research article: Pinto NR, et al. (2014) ISSN 2307-5295, Published by the POSEIDO Organization & Foundation under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License by far the heaviest clot and quantity of exudate among the 4 techniques. For clot and membrane length and width, Intra-Spin and Salvin presented similar sizes. A-PRF and LW produced much lighter, shorter and narrower clots and membranes than the 2 other centrifuges. Light microscopy analysis showed relatively similar features for all L-PRF types (concentration of cell bodies in the first half of the fibrin mesh). However, SEM illustrated considerable differences between samples. The original Intra-Spin L-PRF showed a strongly polymerized thick fibrin matrix and all cells appeared alive with a normal shape, including the textured surface aspect of activated lymphocytes. The A-PRF, Salvin and LW PRF-like membranes presented a lightly polymerized slim fibrin gel and all the visible cell bodies appeared destroyed (squashed or shrunk). Discussion and Conclusion. This study illustrated that the centrifuge characteristics (particularly the vibrations) are directly impacting the architecture and cell content of a L-PRF clot. The original L-PRF clot (Intra-Spin) used and validated since years presented very specific characteristics, which appeared distorted when using centrifuges with a higher vibration level. A-PRF, LW and Salvin centrifuges produced PRF-like materials with a damaged and almost destroyed cell population through the standard 400g protocol developed initially for the L-PRF, and it is therefore impossible to classify these products in the L-PRF family. A-PRF, LW and Salvin centrifuges are not suitable for the production of original L-PRF clots and membranes at 400g. Further research would be interesting to evaluate how modifications of the protocol alone (for example reduction of the g forces) may influence the biological signature of the L-PRF clots and membranes, independently from the characteristics of the centrifuge.
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    ABSTRACT: The aim of this prospective study was to document, radiographically, changes in the apical bone levels on microthreaded implants placed in subsinus residual bone height, according to a bone-added osteotome sinus floor elevation technique with platelet-rich fibrin (PRF) as grafting material. Implants were placed using PRF as grafting material in the bone-added osteotome sinus floor elevation (BAOSFE) technique. The survival rate at abutment tightening (6 to 12 weeks of healing) and at 1 year was calculated. The radiographic analysis determined on consecutive radiographs: 1) the mean residual bone height (RBH) under the maxillary sinus at implant placement; and 2) the change in endosinus bone level. Mean and standard deviation were used to assess the endosinus bone changes in the mesial and distal implant sides at 1 year. Between December 2004 and June 2005, 20 consecutive patients were included in the study after bone height measurement by periapical radiographs. Patients included 14 women (70%) and 6 men (30%) with a mean age of 54.8 +/- 11.1 years, range 35 to 73 years; they were treated with 35 Astra Tech implants (Astra Tech Dental Implant System; Astra Tech, Mölndal, Sweden) fulfilling the inclusion criteria. The mean healing time before abutment tightening was 8.3 +/- 1.4 weeks (range 6-12 weeks); by this time, 1 implant was mobile and was removed. At 1 year, all implants were clinically stable and the definitive prostheses were in function, resulting in a survival rate of 97.1%. Nineteen implants (55%) were 11 mm long, 6 implants (17%) were 9 mm, 5 implants (14%) were 8 mm, and 5 implants (14%) were 13 mm. The RBH was measured after implant placement on the radiographs on both implant sides. The mean RBH was 6.5 +/- 1.7 mm: 6.3 +/- 1.3 on the mesial side and 6.7 +/- 2.0 mm on the distal side. Measurements of the changes in the endosinus level on the mesial and distal sides showed that all implants gained endosinus bone. The mean endosinus gain was 3.2 +/- 1.5 mm: 3.5 +/- 1.4 mm on the mesial side and 2.9 +/- 1.6 mm on the distal side. The lowest bone gain was 0.9 mm and 0.1 mm on the mesial and distal sides, respectively. The highest gain was 5.8 mm and 5.2 mm on the mesial and distal sides, respectively. The BAOSFE procedure with PRF as grafting material can lead to an endosinus bone gain. Despite a limited RBH, a healing period of 2-3 months was found to be sufficient to resist a torque of 25 N.cm applied during abutment tightening. At 1 year, formation of a new recognizable bone structure delimiting the sinus floor was identified radiologically and led to a predictable implant function.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 06/2008; 105(5):572-9. DOI:10.1016/j.tripleo.2007.08.021 · 1.46 Impact Factor
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    Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 02/2008; 66(1):183-8. DOI:10.1016/j.joms.2005.12.050 · 1.28 Impact Factor
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    Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 02/2008; 66(1):177-82. DOI:10.1016/j.joms.2005.12.054 · 1.28 Impact Factor
  • P Leclercq, D M Dohan
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    ABSTRACT: The use of a fixed transitional prosthesis in implantology remains quite seldom, although the concept of temporization and progressive loading of prosthetic restorations has become a main issue in modern dentistry. Fixed tansitional prostheses play an important role in the validation of full-arch implant-supported restorations, and in the success of implant treatments in general. This paper reviews the basic treatment principles, and discusses the different technical options available to the clinician. In simple cases, a hard resin bridge may be sufficient. However, for complex cases, we should better use fixed implant-supported temporary prosthesis, made in resin on a metallic infrastructure. Moreover, this one could be use as the framework of the permanent prosthesis. This technical solution offers the best guaranty for implant and oral rehabilitation validation before the permanent prosthesis installation.
    Revue de Stomatologie et de Chirurgie Maxillo-faciale 01/2008; 108(6):530-5. · 0.39 Impact Factor
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    ABSTRACT: Reverse piezoelectricity is currently used in Dentistry for ultrasonic scaling devices. Using this technology, increasingly more powerful ultrasonic surgical lancets were developed within a few years, and these new tools have provided many practical solutions in oral and maxillofacial surgery. This article reviews the basic principles of piezosurgery, and its numerous clinical applications: in oral surgery (atraumatic extractions, wisdom teeth exposure, periapical cyst debridement, pre-prosthetic surgery), more specifically in periodontal (root planning and bone remodeling, crown lengthening) and implant surgery (sinus lift, removal of fractured implants, bone ridge augmentation, bone graft harvesting (crestal, retromolar, chin or tori)). The recent increased power of these instruments allows emphasizing a much wider range of clinical applications, extending to all surgical fields.
    Revue de Stomatologie et de Chirurgie Maxillo-faciale 12/2007; 108(5):431-40. DOI:10.1016/j.stomax.2007.08.002 · 0.39 Impact Factor
  • P. Leclercq, D. M. Dohan
    Revue de Stomatologie et de Chirurgie Maxillo-faciale 12/2007; 108(6):530-535. DOI:10.1016/j.stomax.2007.06.021 · 0.39 Impact Factor
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    ABSTRACT: To analyze the effects of PRF (a platelet and immune autologous concentrate) on in vitro proliferation of human keratinocytes and preadipocytes, and to determine if these results may offer an opening on new clinical investigations, particularly in the improvement of tympanoplasties and facial lipostructures (Coleman's technique). Human tympanic keratinocytes and preadipocytes are collected and cultured using the explant technique. 4 series of each type of cells are cultivated either in normal condition (control group) or with PRF (test group). The Petri dishes (of culture) are taken out on the 3rd, 7th, 14th and 21st day, for counting. Evolutions of cells' number are analyzed with a variance test. The number of cells in culture increases of more than 60% on the 7th day, and of almost 150% right from the 14th day when in presence of PRF. The daily proliferation peak occurs around the 14th day. The two cellular tested types react similarly. The PRF, considered as a healing biomaterial, could be used in tympanic and facial lipostructures surgeries, in order to improve the therapeutic result. Other applications in microsurgery and in plastic surgery may be possible, but specific clinical studies need to validate such protocols.
    Revue de laryngologie - otologie - rhinologie 02/2007; 128(1-2):27-32.
  • F Braccini, D M Dohan
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    ABSTRACT: To evaluate the interest of fibrin PRF clots, a concentrate of platelets and immune factors, for the optimization of the adipocyte graft according to the technique of facial lipostructure described by S. Coleman. Between May 2005 and June 2006, 32 patients (7 men and 25 women) benefited from a Coleman lipostructure with the use of PRF. The average age was 59 years (39 to 72 years). Lipostructure was used alone in 22 patients and associated with a face lift and/or a blepharoplasty in 10 patients. Before the adipocyte graft, a mixture of PRF and greasy supernatant (resulting from the purification of the sample of adipocytes) is deposited on the zones to be grafted in the same way as for lipostructure. For 2 patients, the pretreatment of the site to be grafted with PRF was unilateral. Patients were followed-up for one year. In this series, all the patients were satisfied with the result with minimal associated resorptions. No massive resorption requiring a resumption of lipostructure was noted. In the 2 patients treated with unilateral use of PRF, one notes a light asymmetry, the hemi-face treated with PRF appearing more stable than the side without PRF. No important residual oedema or echymosis were seen on the 3rd post-operative week. By offering a matricial support to angiogenesis and by stimulating the proliferation of pre-adipocytes, the PRF could have a beneficial role on the cicatrization and the consolidation of an adipocyte graft. Further studies are necessary to validate the interest of the PRF during aesthetic lipostructures. The potential uses in plastic surgery of such a biomaterial, easy and fast to produce, without any overcost and with no risk, are very numerous and require from now on to be tested and validated methodically.
    Revue de laryngologie - otologie - rhinologie 02/2007; 128(4):255-60.
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    ABSTRACT: Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. The use of platelet gel to improve bone regeneration is a recent technique in implantology. However, the biologic properties and real effects of such products remain controversial. In this article, we therefore attempt to evaluate the potential of PRF in combination with freeze-dried bone allograft (FDBA) (Phoenix; TBF, France) to enhance bone regeneration in sinus floor elevation. Nine sinus floor augmentations were performed. In 6 sites, PRF was added to FDBA particles (test group), and in 3 sites FDBA without PRF was used (control group). Four months later for the test group and 8 months later for the control group, bone specimens were harvested from the augmented region during the implant insertion procedure. These specimens were treated for histologic analysis. Histologic evaluations reveal the presence of residual bone surrounded by newly formed bone and connective tissue. After 4 months of healing time, histologic maturation of the test group appears to be identical to that of the control group after a period of 8 months. Moreover, the quantities of newly formed bone were equivalent between the 2 protocols. Sinus floor augmentation with FDBA and PRF leads to a reduction of healing time prior to implant placement. From a histologic point of view, this healing time could be reduced to 4 months, but large-scale studies are still necessary to validate these first results.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 04/2006; 101(3):299-303. DOI:10.1016/j.tripleo.2005.07.012 · 1.46 Impact Factor
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    ABSTRACT: Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this second article, we investigate the platelet-associated features of this biomaterial. During PRF processing by centrifugation, platelets are activated and their massive degranulation implies a very significant cytokine release. Concentrated platelet-rich plasma platelet cytokines have already been quantified in many technologic configurations. To carry out a comparative study, we therefore undertook to quantify PDGF-BB, TGFbeta-1, and IGF-I within PPP (platelet-poor plasma) supernatant and PRF clot exudate serum. These initial analyses revealed that slow fibrin polymerization during PRF processing leads to the intrinsic incorporation of platelet cytokines and glycanic chains in the fibrin meshes. This result would imply that PRF, unlike the other platelet concentrates, would be able to progressively release cytokines during fibrin matrix remodeling; such a mechanism might explain the clinically observed healing properties of PRF.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 04/2006; 101(3):e45-50. DOI:10.1016/j.tripleo.2005.07.009 · 1.46 Impact Factor
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    ABSTRACT: Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this third article, we investigate the immune features of this biomaterial. During PRF processing, leucocytes could also secrete cytokines in reaction to the hemostatic and inflammatory phenomena artificially induced in the centrifuged tube. We therefore undertook to quantify 5 significant cell mediators within platelet poor plasma supernatant and PRF clot exudate serum: 3 proinflammatory cytokines (IL-1beta, IL-6, and TNF-alpha), an antiinflammatory cytokine (IL-4), and a key growth promoter of angiogenesis (VEGF). Our data are correlated with that obtained in plasma (nonactivated blood) and in sera (activated blood). These initial analyses revealed that PRF could be an immune regulation node with inflammation retrocontrol abilities. This concept could explain the reduction of postoperative infections when PRF is used as surgical additive.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 04/2006; 101(3):e51-5. DOI:10.1016/j.tripleo.2005.07.010 · 1.46 Impact Factor
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    ABSTRACT: Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates geared to simplified preparation without biochemical blood handling. In this initial article, we describe the conceptual and technical evolution from fibrin glues to platelet concentrates. This retrospective analysis is necessary for the understanding of fibrin technologies and the evaluation of the biochemical properties of 3 generations of surgical additives, respectively fibrin adhesives, concentrated platelet-rich plasma (cPRP) and PRF. Indeed, the 3-dimensional fibrin architecture is deeply dependent on artificial clinical polymerization processes, such as massive bovine thrombin addition. Currently, the slow polymerization during PRF preparation seems to generate a fibrin network very similar to the natural one. Such a network leads to a more efficient cell migration and proliferation and thus cicatrization.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 04/2006; 101(3):e37-44. DOI:10.1016/j.tripleo.2005.07.008 · 1.46 Impact Factor
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    ABSTRACT: Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this fourth article, investigation is made into the previously evaluated biology of PRF with the first established clinical results, to determine the potential fields of application for this biomaterial. The reasoning is structured around 4 fundamental events of cicatrization, namely, angiogenesis, immune control, circulating stem cells trapping, and wound-covering epithelialization. All of the known clinical applications of PRF highlight an accelerated tissue cicatrization due to the development of effective neovascularization, accelerated wound closing with fast cicatricial tissue remodelling, and nearly total absence of infectious events. This initial research therefore makes it possible to plan several future PRF applications, including plastic and bone surgery, provided that the real effects are evaluated both impartially and rigorously.
    Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 04/2006; 101(3):e56-60. DOI:10.1016/j.tripleo.2005.07.011 · 1.46 Impact Factor
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    ABSTRACT: The use of monobloc posts for implant-supported fixed partial dentures is interesting for biomechanical and biological reasons, but it suffers from a lack of precision during the impression phase. The use of a new generation of monobloc posts associated with individual impression copings with a piston offers a simple and efficient impression procedure for small and medium implant-supported fixed partial dentures. This article presents the FM-Clip system for EVL implants composed of new straight monobloc posts and small impression copings with a piston for precise impressions and easy production of implant-supported fixed partial dentures.
    Journal of Oral Implantology 02/2006; 32(5):251-5. DOI:10.1563/810.1 · 0.98 Impact Factor
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    ABSTRACT: The FM-Clip® system is a conceptual and technical evolution in the use of monobloc posts for implant-supported prostheses. This system has been developed for short and medium range implant-supported bridges on EVL® implants from SERF®; it is an easy to use and precise impression system for simplified production of temporary or final bridges. It then offers a new relationship between implantologists and general dental practitioners: with these new monobloc posts, the implantologist can easily validate the esthetic and functional integration of the implants with a temporary prosthesis; the general dental practitioner will then easily make the final prosthesis. The FM-Clip® system is thus particularly efficient during the transmission of patients.
    Implantodontie 10/2005; DOI:10.1016/j.implan.2005.10.007
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    ABSTRACT: Basal implantology is a rising discipline with wide and multiple applications still unrecognized today. Indeed, if the technology of the set sat back implants exists for more than 20 years, the development of associated therapeutic remains very confidential. This article points out the main historical steps, theoretical bases and technological principles, before describing in details the associated surgical techniques and their therapeutic implications. Thus it emphasises the global treatment of single and complex anatomical lesions of the low and middle face. Finally, if the strictly dental use of these implants are very interesting, the underlying orthopaedic concept shows its great efficacy only during huge and delicate rehabilitations.
    EMC - Odontologie 09/2005; 1(3):202-255. DOI:10.1016/j.emcodo.2005.07.002
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    D. Dohan, A. Diss
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    ABSTRACT: The 2nd International Symposium on Growth Factors (SyFac 2005) gathered more than 600 participants in Nice on Saturday 28 May 2005. This event makes the latest update on fundamental and clinical data related to 3 platelet concentrates types (PRP, PRF, PRGF) currently used during bone grafts, implant, periodontal and maxillofacial surgery.
    Implantodontie 07/2005; DOI:10.1016/j.implan.2005.09.002