Jacques Yachouh

Polyetheretherketone (PEEK) for medical applications

Polyetheretherketone (PEEK) is a polyaromatic semi-crystalline thermoplastic polymer with mechanical properties favorable for bio-medical applications. Polyetheretherketone forms: PEEK-LT1, PEEK-LT2, and PEEK-LT3 have already been applied in different surgical fields: spine surgery, orthopedic surgery, maxillo-facial surgery etc. Synthesis of PEEK composites broadens the physicochemical and mechanical properties of PEEK materials. To improve their osteoinductive and antimicrobial capabilities, different types of functionalization of PEEK surfaces and changes in PEEK structure were proposed. PEEK based materials are becoming an important group of biomaterials used for bone and cartilage replacement as well as in a large number of diverse medical fields. The current paper describes the structural changes and the surface functionalization of PEEK materials and their most common biomedical applications. The possibility to use these materials in 3D printing process could increase the scientific interest and their future development as well.

Prognostic value of a three-grade classification in primary epithelial parotid carcinoma: Result of a histological review from a 20-year experience of total parotidectomy with neck dissection in a single institution

BACKGROUND The tumour grading of primary parotid cancers (PPCs) remains controversial. METHODS A 20-year standardised single centre treatment has been assessed retrospectively. The histological review of 155 consecutively treated parotid malignancies identified 96 suitable cases for univariate and multivariate survival analyses. RESULTS Treatment involved total parotidectomy, neck dissection and post-operative radiotherapy in, respectively, 91.7%, 83.3% and 70.4% of cases. The 5-year overall survival, disease-specific and recurrence-free survival rates were 79.4%, 83.5% and 70.8%, respectively. Univariate analysis confirmed the classical prognostic factors, i.e. age>60 years, male gender, facial palsy, hardness of the tumour, clinical stage, tumour grade, facial nerve invasion and lymph node metastases. Multivariate analysis identified a three-grade classification just after the clinical stage as the most important prognostic factor. CONCLUSION This study identifies the prognostic significance of intermediate grade tumours.

In vitro investigation of fluorescence of carious dentin observed with a Soprolife® camera

ObjectivesOur aim was to determine the origin of the red fluorescence of carious dentine observed with the Soprolife® camera.MethodsWe conducted in vitro studies to evaluate the origin of the red fluorescence using acids and matrix metalloproteinase (MMP) to mimic caries and methylglycoxal (MGO) to evaluate the effect of glycation reactions on the red fluorescence. In every step of these models, we detected the changes of dentin photonic response with Soprolife® in daylight mode and in treatment mode. A Raman spectroscopy analysis was performed to determine the variations of the dentin organic during the in vitro caries processes. Raman microscopy was performed to identify change in the collagen matrix of dentine.ResultsThe red fluorescence observed in carious dentine using a Soprolife® camera corresponds to the brownish color observed using daylight. Demineralization using nitric acid induces a loss of the green fluorescence of dentine. The red fluorescence of carious dentine is resistant to acid treatment. Immersion of demineralized dentine in MGO induces a change of color from white to orange-red. This indicates that the Maillard reaction contributes to lesion coloration. Immersion of demineralized dentine in an MMP-1 solution followed by MGO treatment results in a similar red fluorescence. Raman microspectroscopy analysis reveals accumulation of AGEs product in red-colored dentine.ConclusionsOur results provide important information on the origin of the fluorescence variation of dentine observed with the Soprolife® camera. We demonstrate that the red fluorescence of carious dentine is linked to the accumulation of Advanced Glycation End products (AGE).Clinical relevanceThe study provides a new biological basis for the red fluorescence of carious dentine and reinforces the importance of the Soprolife® camera in caries diagnostics.

Complications of condylar fracture osteosynthesis.

Background:Condylar fracture osteosynthesis is today commonly practiced, but only a few studies deal with complications due to plates or screws loosening. Methods:We made a retrospective analysis of 53 operated condylar fractures treated with different fixation devices from July 2002 to July 2007. We looked for complications and its relationship with the osteosynthesis device used. Results:We found 11.3% complications due to plate fracture, plate torsion, or screw loosening. Those occurred at 2.75 months after surgery on average. Discussion:When performing condyle osteosynthesis, one must keep in mind that plates must be located on the posterior border of the ramus and below the mandibular incisure to respect mastication strains. In our study, the number of plates or the number of screws per plate was not always ideal. Moreover, we started active physiotherapy the day after surgery, which is too early because titanium plates are too weak to support all the mandibular strains. A well-adapted osteosynthesis associated with a progressive load of the temporomandibular joint should limit postoperative plate fracture or torsion.

Osteogenic capacity of vascularised periosteum: An experimental study on mandibular irradiated bone in rabbits☆

BACKGROUND Free flaps are presently the best way to treat advanced mandibular ostonecrosis. Nevertheless, the functional and morphological results can be improved. To avoid a mandibular resection, a free periosteal flap was envisioned. In a preliminary study, the authors opted for a pedicled periosteal flap and evaluated the effect of the latter on regeneration of a rabbit irradiated mandibular bone. METHODS Two bone fragments were taken from the basilar part of the mandible of 15 rabbits through skin incision. Those fragments were then exposed to a 30-Gy irradiation. One bone fragment was implanted in a pedicled periosteal flap elevated from the medial aspect of the femur while the other was subcutaneously fixed as a control. We retrieved the fragments at day 10, 20, 30 and 90 to make a histological analysis without prior decalcification using histomorphometry technique. RESULTS In the periosted fragments, an increased osteoblastic and osteoclastic activity as well as neovascularisation evoked intense remodelling. In the subcutaneous fragments, bone resorption was much more important than osteogenesis and vessels were absent. CONCLUSION We have concluded than periosteum, which has already been proven to be efficient in normal bone regeneration, can be just as such efficient in irradiated bone regeneration.

Impact of genioplasty on mandibular growth during puberty.

AIM Genioplasty has been validated for the correction of mandibular vertical excess and is generally performed at the end of the growth period, either alone or in association with other forms of osteotomy. Our aim was to assess whether genioplasty performed at an earlier age can impact mandibular growth. METHODS This comparative prospective study included 25 high-angle, mouth-breathing adolescents following orthodontic and ENT treatment. Subjects were divided into two groups according to their stage of puberty, either early (group 1: Tanners stage 3, n=12) or late stage (group 2: Tanner stage 4-5, n=13). Genioplasty was performed in both groups. Cephalometric comparison was made on the overall population and for each group, before and after genioplasty (at 1, 6, 12 and 18months). RESULTS In the immediate postoperative period, significant variation of all the cephalometric measures was observed within each group showing reduction of the vertical dimension and sagittal augmentation. Eighteen months post-surgery, only group 1 exhibited a significant increase in SNPog. Augmentation of the SNB and anterior mandibular rotation were also significantly greater in group 1. The difference in the direction of growth of the mandible before genioplasty (18months of orthodontics) and postgenioplasty (18months of postoperative monitoring) was also significant. CONCLUSION Early genioplasty permits redirection of mandibular growth conducive to orthopedic correction of high angle Class II.

A New Rat Model for Translational Research in Bone Regeneration.

The European Union (EU) directive 2010/63/EU on the protection of animals used for scientific purpose focused on reducing the number of animals and refinement of breeding. Animal studies are necessary to protect human health. Lots of animal models exist to study bone regeneration, but a reliable, well reproducible, and relatively inexpensive model with the possibility for multiple testing in the same animal is still missing. Rats may serve as good models for this due to the small animal size and good cost/benefit ratio. The present study aimed to develop a novel rat caudal vertebrae critical size defect model for bone regeneration and implant osseointegration studies The study was performed using Wistar rats with weight from 380 to 450 g. An incision was made on the dorsal side of the tail. After skin and muscles retractions, the vertebrae were exposed. Critical size defects for bone tissue engineering or implant placements for titanium body experiments were possible in each of the first four caudal vertebrae. Micro-computed tomography (CT) and histology were used to detect bone growth. There was no bone formation in the defects after 1 or 2 months of healing. When a calcium phosphate biomaterial was used (Bio-Oss®; Geistlich Pharma AG, Wolhusen, Switzerland), a good stability of the material in the defect was noted and bone growth was visible after 1 or 2 months. Results based on implant placement showed good primary stability after 3 months of healing. MicroCT showed integrated implant position through the vertebra. These results suggest that the rat caudal vertebrae may serve as a good new model for studying bone regeneration and implant osseointegration with the possibility of multiple testing within the same experimental animal and the potential to decrease number of experimental animals.

Sprayed Cells and Polyelectrolyte Films for Biomaterial Functionalization: The Influence of Physical PLL–PGA Film Treatments on Dental Pulp Cell Behavior

Further development of biomaterials is expected as advanced therapeutic products must be compliant to good manufacturing practice regulations. A spraying method for building-up polyelectrolyte films followed by the deposition of dental pulp cells by spraying is presented. Physical treatments of UV irradiation and a drying/wetting process are applied to the system. Structural changes and elasticity modifications of the obtained coatings are revealed by atomic force microscopy and by Raman spectroscopy. This procedure results in thicker, rougher and stiffer film. The initially ordered structure composed of mainly α helices is transformed into random/β-structures. The treatment enhanced dental pulp cell adhesion and proliferation, suggesting that this system is promising for medical applications.

Prélèvement suprafascial du lambeau antébrachial radial

INTRODUCTION The aim of this study was to assess the efficacy of dissection of radial forearm flap in a superficial plan above the deep fascia to prevent donor site problems. PATIENTS AND METHODS Eighteen radial forearm flaps were used for orofacial reconstruction: 11 suprafascial flaps and seven infrafascial flaps. We compared in the two groups: flap failure, graft success, tendon adhesions, sensory nerve damage at donor site. RESULTS We observed one case of flap failure in the infrafascial group and one case in the suprafascial group. With suprafascial elevation flap technique, we noted 100% of grafts integration without tendon adhesion. In infrafascial elevation flap technique, four out of seven patients had delayed healing. DISCUSSION The suprafascial dissection of free radial forearm flap creates a superior graft recipient bed ensuring early and complete successful graft.

Multicenter prospective micro-costing study evaluating mandibular free-flap reconstruction

Free-flap mandibular reconstruction is a highly specialized procedure associated with severe complications necessitating re-interventions and re-hospitalizations. This surgery is expensive in terms of health workers’ time, equipment, medical devices and drugs. Our main objective was to assess the direct hospital cost generated by osseocutaneous free-flap surgery in a multicentric prospective micro-costing study. Direct medical costs evaluated from a hospital perspective were assessed using a micro-costing method from the first consultation with the surgeon until the patient returns home, thus confirming the success or failure of the free-flap procedure. The mean total cost for free-flap intervention was 34,009€ (5151–119,604€), the most expensive item being the duration of hospital bed occupation, representing 30–90% of the total cost. In the event of complications, the mean cost increased by 77.3%, due primarily to hospitalization in ICU and the conventional unit. This surgery is effective and provides good results but remains highly complex and costly.