Cast metal post-core systems have a long history of successful use because of their superior physical properties. However, their high elastic modulus can cause stress concentrations within the surrounding radicular dentin, resulting in root fractures. Moreover, the increasing demand for more esthetically appealing and biocompatible restorations has led to the development of tooth-colored, translucent, metal-free post-core systems. Notably, prefabricated zirconia ceramic post systems have been introduced to satisfy this trend toward a heightened awareness of esthetics, whereby the translucency of all-ceramic crowns can be successfully maintained with the use of ceramic post-core materials. Owing to the keen interest in and widespread use of zirconia ceramic post systems, many in vitro studies on zirconia posts have been published in the last 15 years. The aim of this article was to present data about the retention, fracture resistance, microleakage, light transmission, esthetic advantages, and radiodensity of zirconia posts. Two clinical survival rate studies were also presented. Based on the results of these studies, zirconia posts have been shown to improve the esthetic quality of all ceramic crowns and thus their usage is recommended. Apart from literature review, a case report in which a fractured fiber post was replaced with a custom-made zirconia post was also presented.

No abstract

The aim of this study was to compare the shear bond strengths (SBS) of cast, machined, and laser-sintered titanium to dental porcelain. Two kinds of dental porcelains (Titankeramik and Triceram) were applied on cast (Tritan), machined (DC-Titan), and laser-sintered (EOSINT) titanium specimens (n=10). SBS test was conducted, and fracture surface analysis was also performed to determine the failure modes. Two-way ANOVA, Student's t-test, and post hoc test were used to analyze the data (p<0.05). Among the titanium specimens, the SBS values of laser-sintered titanium specimens were significantly higher than the machined and cast titanium specimens (p<0.01). Comparison of Triceram and Titankeramik veneering porcelains showed no statistically significant differences in SBS when they were applied on laser-sintered and cast titanium specimens (p>0.05). Specimens in all the test groups exhibited adhesive or combined failure, with the Titankeramik-machined titanium group exhibiting the highest adhesive failure rate (40%). Results showed that porcelain-titanium bond strengths could be improved by using the new laser sintering technique to produce titanium for prosthodontic applications.

No abstract

Porcelain laminate veneers as esthetic and minimally invasive restorations are being used as an alternative to full veneer crowns. However, the removal of porcelain veneers that have failed may be an uncomfortable and time-consuming procedure because of the high bond strength between the porcelain laminate veneers and the tooth surface. The purpose of this study was to prepare a simple and reliable method for porcelain laminate veneer debonding by using an Er:YAG laser with the scanning method and to determine the amount of lasing time required. Eighty cylindrical specimens with a thickness of 0.7 mm and a diameter of 5 mm were fabricated from Empress II ceramic material. They were cemented on the labial surface of extracted bovine mandibular incisors using Variolink II (Ivoclar Vivadent AG, Schaan, Liechtenstein) and light cured for 40 s. The specimens were randomly divided into four groups of 20. The first group was assigned as the control group and no laser application was performed. The Er:YAG laser was applied on each specimen in the other three study groups for 3, 6, and 9 s by using the scanning method. One second after the lasing, a mechanical force was applied to remove the laminate veneers by using an Instron Universal Testing machine. Results of this study exhibited statistically significant differences between the control group and the three study groups. Intergroup comparison of shear bond strengths of the three study groups showed a statistically significant difference (p = 0.0001). This study showed that all three application times of Er-YAG laser were effective for debonding ceramic laminate veneers by softening the adhesive resin.