Shear bond strength of composite resin repair to conventional Feldspathic versus low fusing dental porcelain

This study evaluated porcelain repair by use of various surface treatments [Hydrofluoirc acid etching, diamond roughening,sandblasting and no surface treatment [control]] for two types of porcelain [conventional feldspathic[CeramcoII]] and low fusing porcelain [Duceram]] bonded with two types of composite resin [light cured hybrid composite resin [Prisma composite] and heat cured inlay composite resin [Charisma composite]]. Shear bond strengths were determined on a universal testing machine. The result revealed that, shear bond strength of conventional porcelain is higher than low fusing porcelain, inlay composite bond beter than light cured composite and the most effective surface treatment was hydrpfluoric acid etching

Retention of carbon fiber post system within the root canal and core retention

This study was directed to evaluate the retention of two core build up materials, composite resin and silver amalgam, and retention of carbon fiber post system within the root canal in comparison to Parapost system after treatment with universal dental adhesive. Specimens of each group were subjected to tensile load to test the retention. The results revealed a significant difference in the retention between the two post system studied. Also carbon fiber post system showed high retention values when used with universal dental adhesive to the root canal or composite resin core material

Dimensional accuracy and stability of a claimed to be stable alginate

Dimensional changes of three brands of irreversible hydrocolloid impression materials were evaluated immediately and after eight different periods of storage up to 96 hours at 100% relative humidity. The manufacturer of one of these brands [Kromopan] claims that the model can be cast within 100 hours with very good results if the impression is kept in a plastic envelope without any other addition. Stone casts were obtained after storage of the impressions for the different periods of time, then horizontal and vertical changes were measured by means of a micrometer. The results showed that the best dimensional accuracy and, the least dimensional change occurred at immediate pour followed by impressions stored for 1/2 hour. While 96-hour-storage time produced the highest dimensional change in all the impressions

Wear of enamel opposing different restorative materials

Extracted central incisors were secured in a wear testing machine opposing to seven different restorative materials to determine the vertical wear of enamel and to evaluate the surface roughness of the tested materials. The rankings of restorative materials from least abrasive to most abrasive were: silver palladium alloy, amalgam alloy, nickel-chromium alloy, composite resin, cerec MKII inlay, VMK95 and VMK68. Also the surface roughness was higher with amalgam alloy, composite and cerec MKII inlay before and after testing than all tested mate