RESUMO
Intraoral repair of fractured porcelain is an acceptable method to avoid replacement and therefore saving time and cost. The purpose of this study was to determine the in-vitro shear bond strengths of composite resin to feldspathic porcelain after different durations of sandblasting and to compare the effect of sandblasting with that of hydrofluoric acid [HF]. In this in-vitro study, 40 porcelain disks were fabricated and randomly divided into 4 groups [n=10]. Porcelain surface in group 1 was etched with 9.5% HF for 2 minutes. Groups 2, 3 and 4 were sandblasted with 50am alumina particles for 5, 10 and 15 seconds, respectively. All specimens received the same silane agent, bonding agent and composite resin. The samples were subjected to 5000 thermal cycles and then underwent shear bond strength testing. The mean bond strength was analyzed with one-way ANOVA. The mode of failure was determined using stereomicroscope and scanning electron microscope. An additional porcelain sample was fabricated and prepared according to the aforementioned protocols in each group and its surface topography was observed by SEM. The mean bond strength was 15/28 [ +/- 3/64], 13/82[ +/- 4/03], 15/77[ +/- 3/94] and 16/54[ +/- 3/73] MPa in the 4 groups, respectively. There were no statistically significant differences among groups. The most common mode of failure was cohesive in porcelain. No statistically significant difference was found in SEM results of different durations of sandblasting. The shear bond strength was not significantly different after various durations of sandblasting treatment. The bond strength after sandblasting was similar to that of HF. SEM showed that HF acid etching and sandblasting patterns were different
RESUMO
Endodontically treated teeth, because of extensive structural defect, have the increased risk of fracture. For desirable reconstruction of coronal tooth structure, the post provide retention, nowadays non - metal post systems were introduced to dentistry. This study compared the fracture strength of maxillary central incisors restored with metallic, fiber composite and ceramic posts. Thirty human maxillary incisors were used in this invitro experimental study. The crown of each incisor was cut off 1 mm coronal to CEJ and perpendicular to the long axis of the tooth by metal disk. The root canals of the teeth were prepared for post after root canal therapy, then three groups of 10 specimen were formed. Teeth restored with Glass fiber, ceramic and prefabricated metallic posts and numbered as group 1, 2 and 3 respectively. Then, all teeth restored with composite core [Z100, 3M] and metal crowns were fabricated and cemented with glass ionomer vitremer luting cement. Specimens were embedded in autopolimerize acrylic resin 4 mm below CEJ, and then secured in a universal testing machine. A compressive load was applied at 135 degrees angle to long axis with crosshead speed of 0.5 mm/min, till fracture occurred and fracture pattern was recorded. The data were collected and analyzed using ANOVA and LSD tests. Fracture resistance by Newton was respectively: 765 +/- 113.26, 790 +/- 95.34, and 614 +/- 105.32 for glass fiber posts, ceramic and metallic groups. Resistance to fracture for glass fiber and ceramic posts was significantly more than Titanium post [P<0.05], but there was no significant difference between glass fiber and ceramic posts. Considering the results, usage of prefabricated glass fiber and ceramic posts are more preferable than prefabricated titanium posts. Because of more undesirable fracture in ceramic posts group than glass fiber, glass fiber posts are recommended