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The "sandwich" technique involves combination of composite resins to etched glassionomer cements, is used today in restorative dentistry. The purpose of this study is to evaluate the bond strength between several composite resins and glass ionomer or cerment cements. Cylindrical specimens of the cements Ketac-Silver, Ionobond and GC-Lining Ce-ment were inserted in a mold and their flat free surfaces were etched for 30". Cylindrical plastic tubes were set upon each one of these surfaces and filled with the Composite resins Durafill, Brilliant Lux, Estilux posterior, Estilux posterior CVS and Herculite XR. Half of the specimens transferred in tap water for 24 hours and the others after thermocycling in the first month, kept for 4 months. Shear bond strengths were determined in Monsanto Testing Machine and some fractured surfaces were examined under SEM. The results of this investigation indicate that this technique produces bond strengths between composite resins and glassioners and the combination type of resin and type of cement, affects the values of the strength. Glass cermeet--small particle resin provides the most effective strength and glass ionomer--microfill resins the least. Storage time and thermocycling don't significantly effect the bond strength. SEM examination showed that all fracture failures were obtained in the cement while the opposite resin surfaces were covered with particles of the cements.

The purpose of this in vitro investigation was to examine the degree of microleakage in class II, MOD, posterior composite resin restorations, in the distal wall of which a layer of 1,5 mm of ceramometallic cement was condensed. Conventional MOD cavities were prepared using 330 and 56 tungsten carbide burs in 20 premolars extracted for orthodontic reasons. In the first group (10 specimens) the gingival floor was located in the enamel, above the cementoenamel junction and in the second group the gingival floor was located below the CEJ. In the mesial box, cervically, a layer of 1,5 mm of ceramometallic cement (Ketac Silver) was condensed and etched with orthophosphoric acid 37%, the cavity was filled with posterior composite resin (Heliomolar, Vivadent) and 24 hours later the specimens were polished using Sof-Lex discs and thermocycled between 4 degrees C and 60 degrees C for 50 cycles of 2 minutes each. The specimens were immersed for 2 hours in 2% basic fuchsin solution, washed, cleaned with acetate solution and split in two halves longitudinally in a mesiodistal direction, using a hard tissue microtome. From the detection of the degree of dye penetration we conclude that: a) In the cervical walls located in cementum, where cermet cement was condensed, minimal dye penetration was detected b) In the opposite side, where the composite resin existed on dentin-cementum, the dye penetration is more severe c) Dye penetration in cavities located in the enamel, is moderate in the areas where cermet cement existed d) No dye was detected in the interface between cermet cement and posterior composite, in most specimens.

Finishing and polishing an amalgam restoration, is considered as an important and necessary step of the restorative procedure. Various polishing techniques have been recommended to success a smooth amalgam surface. The aim of this study was to investigate the influence of three different polishing treatments on the marginal integrity and surface smoothness of restorations made of three commercially available amalgams and a glass-cermet cement. The materials used were the amalgams, Amalcap (Vivadent), Dispersalloy (Johnson and Johnson), Duralloy (Degussa) and the glass-cermet Katac-Silver (ESPE). The occlusal surfaces of the restorations were polished by the methods: I) round bur, No4-rubber cup-zinc oxide paste in a small brush, II) round bur No 4-bur-brown, green and super green (Shofu) polishing cups and points successively and III) amalgam polishing bur of 12-blades-smooth amalgam polishing bur. Photographs from unpolished and polished surfaces of the restorations, were taken with scanning electron microscope, to evaluate the polishing techniques. An improvement of marginal integrity and surface smoothness of all amalgam restorations was observed after the specimens had been polished with the three techniques. Method II, included Shofu polishers, proved the best results in comparison to the methods I and III. Polishing of glass-cermet cement was impossible with the examined techniques.