[Contribution of 3D technology for maxillofacial surgery]. / Apport de la technologie 3D en chirurgie maxillo-faciale.

In recent years, 3D design and printing technology has been successfully used in maxillofacial bone reconstruction procedures. We had the opportunity to observe its benefits in the manufacture of custom facial implants. The production is so precise that perfect anatomical congruence and biocompatibility are possible. Within the plastic and maxillofacial surgery department of the University Hospital of Liège, we had the opportunity to perform two operations requiring facial skeleton redefinition implants. The purpose of this article is to highlight the current possibilities of facial prostheses via new 3D techno¬logies, but also the advantages and possible complications of this type of surgery.

Depuis quelques années, la technologie dite «conception et impression 3D¼ s'utilise avec succès dans les interventions de reconstruction osseuse maxillo-faciale. Nous en avons apprécié les bénéfices dans la confection d'implants faciaux sur mesure. La finesse de leur réalisation permet d'obtenir une parfaite congruence anatomique avec la meilleure biocompatibilité. Au sein du service de Chirurgie plastique et maxillo-faciale du CHU de Liège, nous avons effectué deux interventions avec implants 3D redéfinissant le squelette facial. Le but de cet article est de mettre en évidence les possibilités actuelles des implants faciaux via les nouvelles technologies 3D, mais également les avantages et les complications éventuelles de ce type de chirurgie.

[Osteo-odonto-keratoprosthesis: a tooth to regain sight]. / L'ostéo-odonto-kératoprothèse : une dent pour retrouver la vue.

As the leading cause of blindness in the world, corneal diseases are second only to cataracts. However, the epidemiology of corneal disease is complex and includes a wide variety of infectious and inflammatory eye diseases (trachoma), immune sequelae (cicatricial pemphigoid on Lyell's disease) of after trauma (chemical burn). The general treatment for severe corneal disease is the corneal transplantation with penetrating keratoplasty. However, the failure of this treatment is virtually certain when the ocular surface is severely compromised. Keratoprosthesis is therefore the only viable option to restore vision in these patients. Only practiced by less than a dozen teams in the world, the osteo-odonto-keratoprosthesis (OOKP) is regularly practiced at the University Hospital of Liège, thanks to a close collaboration between the ophthalmology and maxillofacial surgery teams. Thanks to removal of a tooth and his bone support, patients suffering from bilateral dry eye following pathologies such as burns or cicatricial pemphigoid can benefit from this technique in order to recover an optimal visual acuity in a sustainable way.

En tant que cause majeure de cécité dans le monde, les maladies de la cornée se trouvent au second rang après la cataracte. L'épidémiologie des maladies cornéennes est complexe et englobe une grande variété de maladies oculaires infectieuses (trachomes) et inflammatoires, de séquelles immunitaires (pemphigoïde oculaire cicatricielle, syndrome de Lyell) ou après traumatisme (brûlure chimique). Le traitement habituel en cas de maladie cornéenne grave est la greffe cornéenne par kératoplastie transfixiante. Cependant, l'échec de cette technique est pratiquement inéluctable lorsque la surface oculaire est gravement compromise. La kératoprothèse représente alors la seule option viable pour restaurer la vue chez ces patients. Seulement pratiquée par moins d'une dizaine d'équipes dans le monde, la technique de l'ostéo-odonto-kérato-prothèse (OOKP) est pratiquée au CHU de Liège. Elle nécessite une collaboration étroite entre ophtalmologues et chirurgiens maxillo-faciaux expérimentés. Grâce au prélèvement d'une dent et de ses tissus de soutien, les patients atteints de cécité cornéenne bilatérale peuvent bénéficier de cette technique afin de récupérer une acuité visuelle optimale de manière durable.

[Sleep bruxism : state of the art and management]. / Bruxisme nocturne : actualités et prise en charge.

Although well studied since the 50's, bruxism remains a largely unknown pathology. Its origin is complex, mixing psychological as well as neurological, odontological and hypnic aspects. However, the few analyzes performed on this topic have allowed to set convincing etiopathological hypotheses, including central dysregulation of the dopaminergic system as well as of the neuro-masticatory system. To avoid harmful consequences as headaches, temporomandibular disorders and premature dental scuffs / fractures, it is mandatory to diagnose bruxism as early as possible. For this purpose, and in addition to anamnestic and clinical data, the practitioner can confirm diagnosis with polysomnography, including electromyographic study of masticatory muscles and audiovisual recording. Some orthodontic, pharmacological and psychological solutions have already proved efficient. Nevertheless, a better knowledge of causative neurobiological mechanisms would allow to foresee etiology-based treatments.

Le bruxisme reste, à l'heure actuelle, une pathologie relativement mal connue, bien que déjà étudiée depuis le début des années 50. Son origine est complexe, impliquant des composantes psychologiques, neurologiques, odontologiques et hypniques. Les quelques analyses réalisées à ce sujet ont, toutefois, permis de mettre en avant certaines hypothèses étiopathogéniques convaincantes, notamment un dérèglement central du système dopaminergique et du système neuromasticateur. Un diagnostic rapide de l'affection permettra de réduire ses complications (céphalées, désordres temporomandibulaires, abrasion et fractures dentaires prématurées). Au-delà de l'anamnèse et de l'examen clinique, le praticien pourra confirmer le diagnostic par polysomnographie, incluant une étude électromyographique des muscles masticateurs et un enregistrement audiovisuel. Certaines solutions orthodontiques, pharmacologiques et psychologiques ont déjà prouvé leur efficacité. Néanmoins, une meilleure connaissance des mécanismes neurobiologiques incriminés permettrait d'envisager un traitement étiologique.

Kinetic and spectroscopic study of 1O2 generation from H2O2 catalyzed by LDH-MoO4(2-) (LDH=layered double hydroxide).

Layered double hydroxides (LDHs), exchanged with molybdate, decompose H2O2 to form one molecule of singlet-state dioxygen (1O2) from two molecules of H2O2. The dependence of the kinetics of H2O2 decomposition on Mo and H2O2 concentrations and on temperature has been related to structural characteristics of the material (X-ray diffraction (XRD), scanning electron microscopy (SEM), IR spectroscopy, N2 adsorption, thermogravimetry) and to molybdate speciation as revealed by in-situ studies in the presence of peroxide (FT Raman, diffuse reflectance UV/visible spectroscopy). The H2O2 decomposition rate is linearly correlated with the amount of LDH-exchanged molybdate, except when a considerable fraction of the molybdate occupies less accessible interlayer positions. A maximum in the H2O2 decomposition rate as the H2O2 concentration is increased is due to the successive formation of mono-, di-, tri-, and tetraperoxomolybdates. This behavior was modeled successfully by using the equilibrium constants for formation of the Mo-peroxo complexes, and the rate constants for decay of the peroxomolybdates with 1O2 liberation. Time-resolved diffuse reflectance and Raman observations of the various MoO4(2-)-peroxide adducts are in line with the proposed kinetic scheme. Of all the Mo-peroxo species on the LDH, the triperoxomolybdate has the highest rate for decay to 1O2. Comparison with the kinetics of dissolved molybdate shows that the monomolecular decay of all peroxomolybdate species proceeds much faster at the LDH surface than in solution. Consequently, maximal rates per Mo atom are at least twice as high for the heterogeneous LDH catalyst as for the homogeneous systems.

Behavior of Triticum durum Desf. arabinoxylans and arabinogalactan peptides during industrial pasta processing.

Three industrial pasta processing lines for different products (macaroni, capellini and instant noodles) were sampled at three subsequent stages (semolina, extruded, and dried end products) in the process. Arabinoxylans (AX) and arabinogalactan peptides (AGP) were analyzed. Although very low endoxylanase activities were measured, the level of water-extractable AX (WE-AX) increased, probably because of mechanical forces. No change was observed in the level and structural characteristics of AGP. The WE-AX molecular weight (MW) profiles showed a very small shift toward lower MW profiles; those of AGP revealed no changes as a result of the production process. After separation of WE-AX and AGP, (1)H NMR analysis and gas chromatography of the alditol acetates obtained following hydrolysis, reduction, and acetylation revealed no changes in the arabinose substitution profile of the WE-AX samples during pasta processing. At optimal cooking times, WE-AX losses in the cooking water are small (maximally 5.9%). However, the loss of AGP is more pronounced (maximally 25.0%). Overcooking led to more losses of both components.

Physical stabilisation of amorphous ketoconazole in solid dispersions with polyvinylpyrrolidone K25.

The glass forming properties of ketoconazole were investigated using differential scanning calorimetry (DSC), by quench cooling liquid ketoconazole from T(m)+10 to 273.1 K, followed by subsequent heating at 5 K/min to T(m)+10 K. It was shown that liquid ketoconazole forms a glass which did not recrystallise following reheating, indicating its stability; T(g) was found to be 317.5+/-0.3 K. However, the presence of a small amount of crystalline ketoconazole was able to convert the amorphous drug back to the crystalline state: the addition of only 4.1% (w/w) of crystalline material converted 77.1% of the glass back to the crystalline state, and this value increased as the amount of added crystals increased. PVP K25 was found to be highly effective in the prevention of such recrystallisation, but only if the amorphous drug was formulated in a solid dispersion, since physical mixing of amorphous ketoconazole with the polymer resulted in recrystallisation of the former compound. Storage of the solid dispersions for 30 days at 298.1 K (both 0 and 52% RH) in the presence or absence of crystals did not result in recrystallisation of the amorphous drug. Solid dispersions formed compatible blends as one single T(g) was observed, which gradually increased with increasing amounts of PVP K25, indicating the anti-plasticising property of the polymer. The values of T(g) followed the Gordon-Taylor equation, indicating no significant deviation from ideality and suggesting the absence of strong and specific drug-polymer interactions, which was further confirmed with 13C NMR and FT-IR. It can be concluded therefore that the physical mechanism of the protective effect is not caused by drug-polymer interactions but due to the polymer anti-plasticising effect, thereby increasing the viscosity of the binary system and decreasing the diffusion of drug molecules necessary to form a lattice.

Variation in the degree of D-xylose substitution in water-extractable European durum wheat (Triticum durum desf.) semolina arabinoxylans.

Durum wheat (Triticum durum Desf.) semolina water-extractable arabinoxylan (TWEAX) (yield 0.28%, arabinose-to-xylose ratio (A/X) 0. 62) was fractionated by a stepwise increase in ethanol concentration (up to 65%). The A/X ratios of the resulting fractions varied between 0.42 and 0.80. With increasing ethanol concentrations, increasing A/X ratios went hand in hand with a relative increase of low molecular weight compounds, indicating that high molecular weight compounds with a low A/X ratio are preferentially precipitated from alcohol/water mixtures. (1)H NMR showed that, whereas in TWEAX the levels of unsubstituted xyloses (X(0)), monosubstituted (X(1)), and disubstituted (X(2)) xyloses were 63.1%, 11.8%, and 25.1%, respectively, fractions that precipitated with increasing ethanol concentrations had decreasing levels of X(0). Simultaneously, the level of X(1) decreased equally until it leveled of at ca. 10%. Concomitantly, the level of X(2) increased. The levels of X(0), X(1), and X(2) varied between 69.7% and 53.4%, 18.2% and 10.7%, and 12.2% and 35.9%, respectively.

Distribution and structural variation of arabinoxylans in common wheat mill streams.

In 19 wheat-milling fractions total pentosan content, calculated as 0.88 x (% L-arabinose + % D-xylose), varied between 1.44 and 30.66% on dry matter (dm). It increased with ash content once the latter exceeded 0.6% (dm basis). Water-extractable arabinoxylans were recovered by saturating water extracts to 65% ethanol. Their contents in the milling fractions varied between 0.35 and 1.38%, and above 0.6% ash content also increased with this parameter. Their L-arabinose-to-D-xylose ratios ranged between 0.65 and 0.39, with the lowest values found for the fractions with highest ash content, indicating that the ash-rich tissues contain more arabinoxylans that are less branched. (1)H NMR spectroscopy revealed that the decrease in L-arabinose-to-D-xylose ratio was accompanied by an increase in unsubstituted xylose residues and a decrease in disubstituted xylose residues, while the contents of monosubstituted xyloses were virtually constant.

The 27Al DOR NMR characterization of the molecular sieve AlPO4-8.

27Al double rotation (DOR) NMR spectroscopy has been applied to investigate the framework ordering in the aluminophosphate molecular sieve AlPO4-8 during the hydration process. Relative well-resolved peaks in the DOR spectra of both dehydrated and successively rehydrated AlPO4-8 allow the isotropic shifts and the quadrupolar shifts to be correlated with the local framework structure. The rather complex interaction of water with AlPO4-8 occurs in a specific way, not randomly. For dehydrated AlPO4-8 efforts are shown to correlate respectively the isotropic shifts to the mean Al-O-P angles and the quadrupolar coupling constants to the shear strains of the different aluminium sites.

Determination of ionisation chamber collection efficiency in a swept electron beam by means of thermoluminescent detectors and the "two-voltage" method.

Two methods for determining the collection efficiency of a 0.6 cm3 thimble ionisation chamber exposed to the swept electron beam of a linear accelerator Therac 20 Saturne (CGR MeV) have been compared. In one method the chamber signal has been compared to that of simultaneously exposed thermoluminescent LiF dosemeters (TLD), in the other the "two-voltage" method of Boag, adapted for swept beams, has been used. By variation of the electron energy between 20 and 13 MeV, of the focus-skin-distance (FSD) between 200 and 100 cm and of the monitor rate between 400 monitor units (m.u.) and 100 m.u. per minute, different values could be produced for the peak charge density M. The collection efficiency of the chamber, operating at a standard voltage of 250 V, decreases from 0.99 to 0.84 for a charge density increasing from 0.3 X 10(-4) C/m3 to 7.5 X 10(-4) C/m3, respectively. The maximum deviation observed between the TLD and the "two-voltage" method adopted for similar M is never more than 2% and mostly smaller than 1%. It can be concluded that, under the present experimental conditions, the calculated ionisation chamber collection efficiency is confirmed by the experimental method using TL dosimetry.