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Ceramic Crowns (ceramic + crown)
Selected AbstractsEffect of Aging on Coronal Microleakage in Access Cavities through Metal Ceramic Crowns Restored with Resin CompositesJOURNAL OF PROSTHODONTICS, Issue 5 2010Ali Abdullah Alwan Al-Maqtari BDS Abstract Purpose: The purpose of this in vitro study was to determine if packable resin composite with/without flowable resin composite has the ability to prevent coronal leakage in restored endodontic access openings following aging. Materials and Methods: Eighty simulated standardized access cavities of metal-ceramic crowns were fabricated and fixed on Vitrebond cavities filled with an epoxy resin. The specimens were randomly divided into two main groups: (1) Group A,Access cavities filled with only packable composite (Filtek P60); (2) Group B,Access cavities filled with Filtek P60 and a flowable composite (Filtek Z350) as liner. Each main group was further subdivided randomly into four subgroups according to water storage and thermocycling periods. All specimens were immersed in blue ink solution for 24 hours and then sectioned into quadrants. The extension of blue ink along the metal-ceramic crown/composite resin interface was measured linearly using image analyzer and then analyzed by three-way ANOVA and independent t -test with a Mann-Whitney test. The level of significance was set at p < 0.05. Results: All tested subgroups demonstrated different levels of microleakage. There was no significant difference related to restorative technique; however, there was a significant difference related to water storage and thermocycling. Conclusions: All tested techniques and materials in this study showed microleakage. Packable composite while a flowable liner showed a marginally better result than packable composite alone. Excessive thermocycling resulted in significant differences among the test groups. [source] Influence of abutment substrate and ceramic thickness on the colour of heat-pressed ceramic crownsJOURNAL OF ORAL REHABILITATION, Issue 9 2002T. NAKAMURA Summary All-ceramic crowns made of leucite-based heat-pressed ceramics are widely used to restore non-vital teeth in conjunction with various post and core materials. However, as some light passes through the ceramic, the colour of the abutment substrate can negatively affect the final aesthetic appearance of the all-ceramic crown. In this study, we made background specimens simulating gold-alloy cast posts and other simulating porcelain veneered cast posts, overlaid different thickness of heat-pressed ceramic on these background specimens, and measured the shifts in colour. We found that, when the background specimen was a gold alloy, the background colour had an effect on the apparent colour, unless the ceramic was more than 1ˇ6 mm thick. When the background specimen was porcelain veneered, the background colour had no evident effect, even when the ceramic was not very thick. Therefore, when making a restoration using a leucite-based heat-pressed ceramic crown, it is advisable to use tooth-coloured materials such as a porcelain veneered cast post, if you will not be able to make the ceramic more than 1ˇ6 mm thick. [source] CAD/CAM to fabricate ceramic implant abutments and crowns: a preliminary in vitro studyAUSTRALIAN DENTAL JOURNAL, Issue 1 2009MA Alfarsi Abstract Background:, This study evaluated the feasibility of fabricating implant abutments and crowns from pre-sintered feldspathic porcelain blocks using the chair-side CAD/CAM, CEREC3DŽ system. Methods:, Thirty-two implant analogues were divided into two groups. In the control group, prefabricated machined anatomical titanium (Ti) abutments were screw-retained to the analogues. In the test group, machined feldspathic porcelain abutments were cemented on prefabricated machined Ti links and screw-retained to the implant analogues. These feldspathic porcelain abutments were fabricated out of pre-sintered feldspathic porcelain blocks as duplicates of the abutments in the control group using the CAD/CAM, CEREC3DŽ system. Thirty-two feldspathic porcelain crowns, also fabricated out of pre-sintered ceramic blocks, were then cemented with resin cement on all the abutments in both groups. All samples were subsequently subjected to fracture strength testing under static load. An unpaired t-test was used to compare fracture load values between the two groups. Results:, The test group using feldspathic porcelain abutments and crowns showed statistically significant higher mean fracture strength than the control group with the Ti abutments and feldspathic porcelain crowns. Conclusions:, This preliminary study showed that the chair-side CAD/CAM technology can be utilized to fabricate customized ceramic abutments with their associated ceramic crowns using pre-sintered feldspathic porcelain blocks. [source] | ||||||||||