Background and objectives: The purpose of this in vitro study was to evaluate the effect of grinding, reglazing and polishing procedures on the surface roughness of monolithic zirconia qualitatively and quantitatively. Materials and methods: Thirty-six disc-shaped yttrium-stabilized zirconium oxide specimens were milled from pre-sintered zirconia blanks using CAD-CAM machine with a diameter of 12mm and thickness of 1.4mm for twenty-seven discs while 12mm and 1.2mm for nine discs as a control group. After that, they were sintered and overglazed. The control group (GA) left untouched while the other twenty-seven specimens were subjected to standardized wet grinded with a coarse diamond rotary instrument. Then they were randomly divided into three groups (nine specimens for each): grinded group (GB) without any additional surface treatment; reglazed group (GC) by adding galze material; polished group (GD) polishing with an intraoral zirconia polishing kit Kenda in a 2-step procedure. Then specimens were evaluated under a stereomicroscope. The surface roughness values were measured with a profilometer for all groups. The mean of surface roughness values was calculated and analyzed using one-way ANOVA and using LSD significant difference tests for comparison between groups (a = 0.05). Results: Stereomicroscopic images revealed that the grinded specimen showed grooves and scratches, reglazed surface showed the same criteria as control with a little bit more evidence of irregularities. While polished specimen appeared smoother and more homogeneity. Statistically significant differences were noted among the experimental groups, in which GB resulted in the highest roughness, GD with the lowest roughness. While GC was close to GA. Conclusions: Roughness significantly increased after grinding, but polishing decreased roughness significantly while glazing restores the smoothness.

The purpose of this in vitro study was to evaluate the marginal interfaces betweentooth structure and the retro-filling materials.Sixty teeth were divided into six groups of ten for each. The teeth wereinstrumented to a minimum of size no. 45 k-file, obturated with gutta-percha, resectedperpendicular to their long axes and prepared to receive a retro-filling. The teeth werefilled with amalgam, resin-modified GIC or light-cured composite resin. Each fillingmaterial was either applied with dentin adhesive or without dentin adhesive.Photomicrographs were made & examined by four evaluators.Statistical analysis of the results revealed that the composite resin had bettermarginal adaptation than the amalgam & the glass ionomer cement, but the differencewas non significant (p>0.05). In addition, the non-adhesive groups together had lessmarginal adaptation than the other groups and the difference was significant (p<0.05).Composite resin retro-filling material had better marginal adaptation than othermaterials used and the dentin adhesive may have effect on the quality of theadaptation.

This study was done to evaluate the microleakage at the tooth restoration interfacein different substrates when glass ionomer was used as a base which covered by aveneer of resin composite, as closed sandwich technique, with light -emitting diode(LED) curing.Eighty Class II cavities were prepared in mesial and distal of extracted molars,mesial cavities with gingival margins in enamel (E) and distal cavities with gingivalmargins in dentin(D), were divided into four main groups (G)s, each group wassubdivided into GE and GD of ten cavities for each and filled as follows:GI each cavity of GIE & GID was filled with composite and cured with halogenlight curing unit (H), GII each cavity of GIIE & GIID was filled with glass ionomerlining and composite and cured as GI, Group III each cavity of GIIIE & GIIID wasfilled as GI but cured with LED while Group IV, each cavity of GIVE and GIVDfilled as GII and cured as GIII. After restorations, the teeth were thermocycled 300times, soaked in 0.1% methylene blue for 24 hours, sectioned and microleakage fromthe gingival margin scored. Statistical analysis was performed using t-test.There was no significant difference when use sandwich technique in enamel butThere was significant difference in dentin (p≤0.05), while no significant differencewhen the comparison between enamel and dentin, whether LED or H curing was used.With sandwich technique, the marginal adaptation of enamel margins was notdependent on the restorative technique while marginal adaptation in dentin wassignificantly better. The use of LED had no adverse effect on microleakage.

The purpose of this in vitro study was to determine whether shear bond strength(SBS) to chemomechanically excavated dentine by Carisolv (CS) differed from theSBS after conventional caries removal by bur (CB), with the use of the followingadhesive systems: [Total-etch (TE), etch and Compobond1, etch, prime and bondingresin]; [Self-etch (SE), Xeno v, one component self-etching dental adhesive] and [Noetch(NE), Compobond1, prime& bond only]. Fifty human molars with occlusal carieswere used to prepare dentin samples which were assigned to 5 groups: group I and IIIthe prepared samples treated by CB and CS respectively then with TE, group II andIV the prepared samples treated by CB and CS respectively then with SE, while ingroup V the prepared samples treated by CS and then with NE. For each sample therewas light cured composite core build up. After water storage, the samples were testedin a single-plane shear test assembly. The results demonstrated that there werestatistical significant differences with in the mode of caries removal groups and alsothere were statistical significant differences between the bonding systems which affectSBS of carious dentin at p < 0.01, with in favor of the TE over SE. The present datademonstrate that with the use of CS on (carious dentin, there was either increase ordecrease in bond strength in relation with different bonding systems.

Objective: The aim of this study was to compare enamel shear bond strength to resin composite following preparation with a carbide bur, fine diamond bur, or erbium doped, yttrium-aluminium-garnet (Er:YAG) laser. Materials & Methods: Forty-eight human anterior teeth, randomly assigned to each preparation group, were studied. Each tooth was mounted in self-curing acrylic resin with the desirable flat facial surface exposed and was randomly assigned to 3 groups according to surface preparation: Er:YAG laser irradiation, carbide bur, or fine-grit diamond bur. A polypropylene cylinder was fixed to the prepared surface, which was demarcated for the area to be bonded with the single bonding system. Restorative composite was then incrementallyinserted into the tubing lumens. The teeth were shear tested to failure at a crosshead speed of 1.0mm/minute. One-way ANOVA and the Tukey test were used for analysis.