• The deformation and strength of a dental ceramic following resin-cement coating.

      Isgró, G; Addison, O; Fleming, G J P; Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Lincoln Place, Dublin 2, Ireland. g_isgro@tiscali.it (2011-02)
      The hypothesis tested was that processing, pre-cementation and cementation techniques can modify the profilometrically measured deformation of a ceramic.
    • Deformation of a dental ceramic following adhesive cementation.

      Isgró, G; Addison, O; Fleming, G J P; Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Lincoln Place, Dublin 2, Ireland. giuseppe.isgro@dental.tcd.ie (2010-01)
      Stress-induced changes imparted in a 'dentin-bonded-crown' material during sintering, annealing, pre-cementation surface modification, and resin coating have been visualized by profilometry. The hypothesis tested was that operative techniques modify the stressing pattern throughout the material thickness. We polished the upper surfaces of 10 ceramic discs to remove surface imperfections before using a contact profilometer (40-nm resolution) to measure the 'flatness'. Discs were re-profiled after annealing and after alumina particle air-abrasion and resin-coating of the 'fit' surface. Polished surfaces were convex, with a mean deflection of 8.4 + or - 1.5 microm. Mean deflection was significantly reduced (P = 0.029) following alumina particle air-abrasion and increased (P < 0.001) on resin-coating. Polishing induced a tensile stress state, resulting in surface convexity. Alumina particle air-abrasion reduced the relative tensile stress state of the contralateral polished surface. Resin-polymerization generated compression within the resin-ceramic 'hybrid layer' and tension in the polished surface and is likely to contribute to the strengthening of ceramics by resin-based cements.
    • Transient and residual stresses in a pressable glass-ceramic before and after resin-cement coating determined using profilometry.

      Isgró, G; Addison, O; Fleming, G J P; Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Lincoln Place, Dublin 2, Ireland. (2011-05)
      The effect of heat-pressing and subsequent pre-cementation (acid-etching) and resin-cementation operative techniques on the development of transient and residual stresses in different thicknesses of a lithium disilicate glass-ceramic were characterised using profilometry prior to biaxial flexure strength (BFS) determination.
    • Transient and residual stresses induced during the sintering of two dentin ceramics.

      Isgró, G; Addison, O; Fleming, G J P; Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Ireland. (2011-04)
      To characterize the stress induced deformation of bi-axial flexure strength (BFS) test specimens during processing to provide an insight into sintering effects and associated BFS determination.