[The frequency of various types of disk displacement and its relation to occlusion]. / Fréquence des différents types de déplacements discaux et rapports avec l'occlusion.

The aim of this study is to observe the frequency of the different types of disc displacements (d.d.) of the TMJ (ATM) and to evaluate if these types are related or not with malocclusions. One hundred patients and 13 asymtomatic volunteers underwent full clinic examination. sagittal MRI (mouth open and closed) and coronal MRI (mouth closed). The different types of disc displacements were noted and cumulated in frequency and in relation with several occlusal criteria. Unlike the general opinion stating that the antero-medial d.d. (d.d. a-m) are the most frequent amongst the internal derangements, the result of this study reveals that the antero-lateral d.d. (d.d. a-l) are more frequent amongst the patients (35.1%) and the asymptomatic volunteers in general and particularly in view of a malocclusion (exagerated anterior overlapping and posterior cross bite). The study gives rise to the question of the etiology of a antero-lateral d.d. and sets back the hypothesis of the lateral pterygoid muscle fundamental role in the disc displacements.

Surface studies on titanium IMZ implants.

The aim of this study was to investigate the surface feature of the IMZ implant. Eight non-implanted new samples and four implanted samples removed one year after insertion were prepared. The 8 non-implanted samples were divided into two groups. The first group was sterilized and the second group was manipulated by bare hands. The implanted samples underwent a careful procedure to recover the metal surface. Then, both the non-implanted new samples and implanted samples were subjected to X-ray electron spectroscopy (XPS) and Rutherford back-scattering spectroscopy (KBS) analyses. Subsequently, all the samples were subjected to scanning electron microscopic (SEM) examination, and surface roughness and profilometric measurements. The SEM photomicrograph showed a rough surface composed of fused granular metal separated by gaps. Sometimes the presence of isolated well-shaped granules of 0.8-1.8 microns in diameter was observed. This structure was related to the manufacturing process of the IMZ implant. The implanted surfaces showed no intergranular gaps and appeared less rough (average roughness: Ra = 1.91 +/- 0.1 microns) compared with the new non-implanted surfaces (Ra = 4.93 +/- 0.3). XPS analysis at a maximum resolution depth of 1.5 nm revealed TiO2, C, O compounds on sterilized non-implanted surfaces. The hand-handled non-implanted surfaces on the contrary did not show TiO2 due to contamination. The elements Ca, C, O and N were found on the one-year implanted IMZ surfaces; TiO2, however, was absent. RBS analysis at a maximum resolution depth of 1000 nm, indicated a decrease of the total thickness of TiO2 after one year of IMZ implantation. The TiO2 thickness was 0.5-0.7 microns for the non-implanted new IMZ surfaces and 0.03-0.2 microns for implanted IMZ surfaces.

[The surface status of polished restoration biomaterials after the use of a sodium bicarbonate spray: scanning electron microscopy]. / Etats de surface des biomatériaux de restauration polies après usage du spray au bicarbonate de sodium: microscopie électronique à balayage.

The effects of an air-abrasive system on polished surfaces of restorative materials have been studied using scanning electron microscopy, metrology and profilography. Polished surfaces of composite resin, of amalgam and gold alloy show different alteration types in microtopography, in profile tracings and significant increased surface roughness after air-abrasive spraying; but ceramic and non-precious alloy surfaces are not affected. The composite resin surfaces should be repolished and amalgam and gold alloy surfaces made glossy after use of an air-abrasive system.

[Changes in the surface microrelief and the loss of dental enamel after the use of an abrasive spray of sodium bicarbonate]. / Altérations du microrelief de surface et perte de l'émail dentaire après utilisation d'un spray abrasif au bicarbonate de sodium.

Alterations of the surface dental microtopography and enamel loss due to the use of an air-abrasive system on polished and no-polished surfaces of extracted teeth, have been evaluated by scanning electron microscopy, and surface roughness and weight measurements. Results show irregular depressions and significant increased surface roughness on no-polished enamel surfaces while polished enamel surfaces are very lightly affected by the air-abrasive system. Enamel loss expressed in weight % attains 1%-5.3% after use of an air-abrasive system.