[A perspective on the use of bone anchorage as opposed to other types of anchorage techniques]. / Mise en perspective de l'utilisation des ancrages osseux par rapport aux autres techniques d'ancrage.

INTRODUCTION: To convert our objectives into the desired treatment results, we need to control our mechanics and thus the anchorage used by avoiding any unwanted movements. It now seems unthinkable, at the dawn of the 21st century, to ignore the useful contribution of orthodontic screw-borne anchorage. Nevertheless, we are entitled to raise a number of legitimate questions. Do these forms of anchorage offer an alternative to all types of mechanics? Will they permit us to manage clinical situations which are beyond the scope of a more classical approach? Can they enhance the quality of our treatments? MATERIALS AND METHODS: Each of the authors describes clinical situations using screw-borne anchorage and compares with a conventional approach in order to make a non-exhaustive analysis of the mechanics applied, in their own office, and then highlights the most effective technique. RESULTS: With 15 years experience in the use of miniscrews, orthodontists have now adopted them with their many advantages as an integral item in their therapeutic armamentarium. However, treatment plans must be coherent. Our mechanics must be well thought-out and represent a cogent entity under the control of the practitioner. Creating screw-borne anchorage demands total control over anchorage stability.

[Alveolar bone thickness in A point area : how to avoid periodontal failures in front of upper incisors]. / Épaisseur d'os alvéolaire dans la zone du point A : savoir éviter les échecs parodontaux en regard des incisives maxillaires.

Studies on orthodontic-periodontics relationships are numerous but few have benefited from the contribution of new 3D imaging techniques that emphasize iatrogenic effects that orthodontics may have on the periodontium. Periodontal risk in terms of fenestration, bone dehiscences next maxillary incisors are real during or after orthodontic treatment. The accurate assessment of the initial situation in terms of bone quantity in this dental arch anterior segment is thus very important. Our study aimed to evaluate the reliability of conventional lateral cephalograms to quantify alveolar bone thickness in relation to the maxillary incisors by comparing it with data from CT scans. The second objective was to identify an at risk patient profile by assessing possible correlations between this thickness and dysmorphia components. The results revealed a half of assessment error in the estimation of bone thickness and increased risk in case of hyperdivergence typology, Class III skeletal relationships and dento-alveolar protrusion. Finally, in view of these data, we discussed the clinical procedures to avoid such periodontal failures in this anterior segment of the dental arch.

Analysis of twenty five impurities in uranium matrix by ICP-MS with iron measurement optimized by using reaction collision cell, cold plasma or medium resolution.

An analytical procedure was developed to determine the concentration of 25 impurities (Li, Be, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ag, Cd, In, Sm, Eu, Gd, Dy, W, Pb, Bi and Th) in a uranium matrix using the quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). The dissolution of U(3)O(8) powder was made with a mixture of hydrochloric acid and nitric acid. Then, a selective separation of uranium using the UTEVA column was used before measurement by Q-ICP-MS. The procedure developed was verified using the Certified Reference Material "Morille". The analytical results agree well except for 5 elements where values are underestimated (Li, Be, In, Pb and Bi). Among the list of impurities, iron was particularly investigated because it is well known that this element possesses a polyatomic interference that increases the detection limit. A comparison between iron detection limits obtained with different methods was performed. Iron polyatomic interference was at least reduced, or at best entirely resolved in some cases, by using the cold plasma or the collision/reaction cell with several gases (He, NH(3) and CH(4)). High-resolution ICP-MS was used to compare the results obtained. A detection limit as low as 8 ng L(-1) was achieved.

Comparison of three dissolution apparatuses for testing calcium phosphate pellets used as ibuprofen delivery systems.

Porous calcium phosphate pellets were produced according to two granulation processes (low and high shear wet granulations) and drug loaded with five ibuprofen contents (1.75%, 7%, 12.5%, 22%, and 36%) in order to ensure both bone defect filling and local drug delivery. The drug-release kinetics from the two types of pellets was studied using three dissolution apparatuses: paddle apparatus, reciprocating cylinder, and flow-through cell. The paper compared the three dissolution methods and considered the effect of the granulation process on the ibuprofen-release kinetics. Dissolution data were analyzed using the Weibull function as well as the difference (f1) and similarity (f2) factors. Dissolution kinetics was not influenced by the granulation process, regardless of the dissolution apparatus and of the drug content. The comparison of the three dissolution devices indicated that ibuprofen was released faster from granules loaded with 36% of drug content with the reciprocating apparatus, due to the disintegration of the granules occurring during the dissolution test. For the other drug contents, dissolution profiles were not significantly different from one apparatus to another. However, the flow-through cell seemed to be more suitable for the drug-release study of implantable materials.

Fabrication of porous substrates: a review of processes using pore forming agents in the biomaterial field.

This paper is a review of solid and casting manufacturing processes able to create porous materials, mainly in the biomaterial field. The considered methods are based on pore forming agents that are removed either by heating or by dissolution. All techniques lead to products presenting pores with amount, size, and shape are close to those of the initial pore formers. Porosities up to 90% with pores ranging from 1 to 2000 microm are reported. Major differences concern macrointerconnections that are more frequently obtained using foams, or porogens which undergo a melting stage during firing. Casting methods combined with solid free form fabrication are promising for the design of porous network through the manufacturing of 3D scaffolds corresponding to the desired porosity.