[Operatory field in bonded dentures: proposals for a rationale]. / Le champ opératoire en prothese collée: propositions pour une rationalisation.

Success in acid-etched dentistry essentially depends on the quality of the adhesion. The bonding session must be carried out with the upmost rigour. The operative field will permit good protection against humidity (saliva, bleeding, gingival fluid, breathing), as well as good instrumental and visual access for finishing. Three different methods are available: retraction (retraction cords), isolation (rubber-dam, "contour strip"), and retraction + combined isolation (thick rubber-dam + suture; mini rubber-dam + suture. The indications depend on the localization in the mouth and the kind of restoration. It is thus necessary to classify the methods so that the selection of the operative field will be simple to work in, quick and systematic. The impossibility of isolating the surfaces to be bonded and to have an access to the margins must be an absolute counter-indication of this technique.

A comparison of two methods of adhering composite to metal.

Composites are used as an esthetic restorative material in prosthetic dentistry, often with a metallic substructure that provides support when large restorations are required. Different bonding systems have been proposed to occupy the gap between the composite and metal and to reduce marginal leakage at this interface, which with time results in a degradation of the metal-composite junction with dissociation of these two materials. This study compared two methods of adhesion of composite to metal: (1) the Silicoater, based on a silanization of metal and (2) the Spectralink, based on an ionization of metal. A total of 108 metal pellets were covered with composite; 36 pellets formed the baseline or control group and 72 pellets were placed on temporary fixed partial dentures for the 12 patients in the study. The two bonding methods were compared at 0, 30, and 90 days. Marginal leakage (< 0.7 microns) and marginal gap (< 0.6 microns) for the baseline groups were minimal and demonstrated no significant difference between the two samples. The degradation of marginal adaptation and hermeticity was faster and more severe with the pellets of the ionization sample. The Silicoater samples exhibited a better hydrolytic resistance with the formation of a hydrophobic polymer. The degradation of the composite-metal interface with the Spectralink method appeared to be the result of the hydrophilic character of polyfluoromethacrylate. Nevertheless, the values of the marginal gap (< 6.0 microns) and the microleakage (< 30.0 microns) remained low for the metal treatments.

[Dental-prosthetic margin in bonded esthetic restorations. Clinical aspects]. / Le joint dento-prothétique des restaurations esthétiques collées. Considérations cliniques.

The long term success of any bonded prosthesis mainly depends on the quality of the marginal adaptation. Its degradation has been noted both at the clinical and the experimental levels. It may be due to biological, chemico-physical, mechanical and clinical factors. Improving the marginal gap closure is based on some principles: the type of preparations on which depends the stabilisation and the good positioning of the restorations; the quality of the clinical isolation which will avoid any humidity on the bonded surfaces (saliva, blood, gingival fluids); the chemical and physical type of the bonding polymer and the quality of its polymerisation; the finishing and final surface condition directly related to the kind of finishing burs used. The understanding and application of these few clinical principles enable the practitioner to expect a better clinical result as regards the bonding of aesthetic restorations.