[Piezoelectric osteotomy: applications in periodontal and implant surgery]. / L'ostéotomie piézoélectrique: applications en chirurgie parodontale et implantaire.

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.

[Influence of platelet rich fibrin (PRF) on proliferation of human preadipocytes and tympanic keratinocytes: A new opportunity in facial lipostructure (Coleman's technique) and tympanoplasty?]. / De l'influence du platelet rich fibrin (PRF) sur la prolifération des préadipocytes et keratinocytes tympaniques humains: une nouvelle opportunité pour la lipostructure faciale (technique de Coleman) et la tympanoplastie?

AIM: 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). MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[The relevance of Choukroun's platelet rich fibrin (PRF) during facial aesthetic lipostructure (Coleman's technique): preliminary results]. / De l'intérêt du platelet rich fibrin (PRF) de Choukroun au cours de la lipostructure faciale esthétique de Coleman: résultats préliminaires.

OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Possible involvement of gelatinase A (MMP2) and gelatinase B (MMP9) in toxic epidermal necrolysis or Stevens-Johnson syndrome.

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.