D. Dohan

Hôpital Albert Chenevier – Hôpitaux Universitaires Henri Mondor, Créteil, Île-de-France, France

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Publications (36)16.79 Total impact

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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. · 1.50 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. · 1.58 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. · 1.58 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. · 0.39 Impact Factor
  • 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: 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.
  • P. Leclercq, D. M. Dohan
    Revue De Stomatologie Et De Chirurgie Maxillo-faciale - REV STOMATOL CHIR MAXILLO-FAC. 01/2007; 108(6):530-535.
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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. · 1.50 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. · 1.50 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. · 1.50 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. 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. · 1.50 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. · 1.50 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. · 1.15 Impact Factor
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    ABSTRACT: Research for protocols supporting haemostasis and cicatrisation is a recurrent problem in all types of surgery. Platelet concentrates, as cytokines-enriched biological adhesives constitute some novel research fields. The first generation of these surgical additives, generally named cPRP (concentrated platelet-rich plasma), come from the autologous fibrin adhesives technologies. The different kinds of cPRP were tested in many clinical situations, particularly in oral and maxillofacial surgery. Moreover, the second platelet concentrate generation, the PRF (platelet-rich fibrin), offers the more efficient clinical applications. Indeed, PRF induces accelerated tissue healing owing to the development of effective neovascularization, accelerated wound closing with fast cicatricial tissue remodelling and almost total absence of infectious events. Platelet concentrates for topical use, particularly the PRF, thus represent some new complementary therapeutic additives, provided its real effects are impartially and strictly evaluated.
    EMC - Odontologie. 01/2005;
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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 01/2005; 1(3):202-255.
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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 01/2005;
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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. 01/2005;
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    ABSTRACT: Toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS) are considered to be drug-induced diseases, and are characterized by extensive mucocutaneous disorder and epidermal necrosis which result in the detachment of the epidermis. Inactive and active forms of metalloproteinases (MMP2 and MMP9) secreted by skin explants maintained in organ culture for 72 h and in blister fluid from two TEN and three SJS patients were investigated. Interestingly, lesional skin from both the TEN and the SJS patients cultured for 3 days in conditioned medium showed high levels of both 72 kDa progelatinase A and 66 kDa activated gelatinase A, and the 66 kDa activated form was not observed in cultures of skin from control individuals. Furthermore, indirect immunodetection showed the presence of MMP2 and MMP9 in TEN and SJS patients' skin. Increased gelatinase activity in the culture medium of TEN and SJS skin maintained in organ culture and in blister fluid indicates that these gelatinases may be responsible for the detachment of the epidermis in these drug-induced necrolyses.
    Archives for Dermatological Research 11/2004; 296(5):220-5. · 2.71 Impact Factor
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    ABSTRACT: The tomodensitometric maxillary reconstitutions belong to the most powerful available tools to control and carry out the implant treatments. However, penumbra and diffusion, two X-ray use indissociable physical phenomena, can largely harm the precision of these radiological examinations. The objective of this article is to present these two phenomena and their consequences in oral implantology. On a toothless maxillary, their association will reveal the interfaces between bone structures and air cavities to the detriment of residual bone volume. On a facial cranium after large exeresis surgery, the increased X-ray diffusion within the cicatricial fibrous masses will induce an overvaluation of the residual bone structures. These two traps are inevitable and it is important to take them into consideration in order to avoid trusting blindly the pre-implant scanners data.
    Implantodontie 10/2004; 13(4):237-241.