[Analysis of some iatrogenic injuries during manual endodontic treatment]. / Analyse de certains dégats iatrogéniques au cours des traitements endodontiques manuels.

Some of various iatrogenic diseases, during manual endodontic treatments, are analysed, from detailed clinical instances. Discussion leads to insist upon some classical and original ways of prevention. From general point of view, it is unavoidable to realize with gentleness, never forcing, endodontic proceedings. Deep perception of internal dental morphology is quite necessary and must be respected during treatment. Besides, histo-pathological modifications of parietal dentine have to be known, not only from intellectual but also from tactile point of view. Each practitioner will progressively improve.

[Comparative study of the seal and porosity of provisional coronal filling materials in endodontics]. / Etude comparative de l'étanchéité et de la porosité des matériaux d'obturation provisoire coronaire en endodontie.

The porosity and the leakage properties of 13 temporary fillings used between each appointment during endodontic treatment were investigated by means of thermocycling and dye staining of the interface between the teeth and the filling material. A scanning electron microscope was also used for these observations. The 8 commercially produced temporary fillings seal adequately the cavity whereas the 5 materials prepared and mixed by the practitioner allowed wide staining diffusion and therefore were leaky.

[Corono-radicular caries: a histoclinical approach]. / Les caries corono-radiculaires: approche histo-clinique.

Due to aging and gingival recession, the radicular structures are exposed to cariogenic attacks from the oral cavity. This phenomenon leads to a constantly higher frequency of root caries. The aspect of these carious lesions was analysed by a histological and an SEM study. To conclude the study, a clinical description of the lesions and an epidemiological survey were realized on 112 patients for 16 months.

[Bonding and enamel prisms. Importance of cavity margin preparation for posterior composites]. / Collage et prismes de l'émail. Importance de la préparation des bords des cavités pour composites postérieurs.

Preparation of the cavo-surface margin for fillings with "composites resins" is an important operative step. The good peripheral fit of the restoration and the stability of the bond between tooth and material depend on that preparation. How should the "bevel" be shaped? Scan electron microscopy of long bevels and rounded bevels show that the former seem more favorable to the fit of the filling. The section of enamel prisms is clean. The aprismatic surface area disappears. This enables to etch the cristallites in a more favorable axis as opposed to the rounded bevel.

[Bonding and enamel prisms: is the "bevel" still significant?]. / Collage et prismes de l'émail: le "biseau" a-t-il encore un intérêt?

Following a recall of the various preparations of the cavo-surface for posterior composites (straight, rounded, concave bevel, or without bevel), a study at the M.E.B. analysed the interface between the tooth and the filling in each case investigated. With the straight bevel with a slight angulation (40 degrees), the limit of the cavity-filling joint is clear. A disintegration of the material exists with the straight bevel having a 70 degrees angulation. The hiatus is even more marked with rounded or concave bevels. The absence of a bevel provides a clear occlusal joint without irregularity at the cavo-surface limit. In the light of this investigation and the results observed in the clinic in the medium and long term, it appears that the preparation of the cavo-surface margins of occlusal cavities of the pre-molars and molars for posterior composites may make do with a bevel which is not very extensive and not widely opened (40 degrees), or even the total absence of a bevel.