No abstract

The clinical outcome of 95 consecutively placed In-Ceram complete coverage crowns, 68 posterior and 28 anterior, all luted with conventional cements, was studied. In the 56 month observation period no total failure requiring replacement of a restoration occurred. The veneer of a molar single crown fractured, while its ceramic core remained intact. With four crowns, marginal caries was observed after 2-4.5 years. It was concluded from this clinical study that In-Ceram complete coverage all-ceramic crowns are indicated for anterior and posterior teeth.

The aim of this study was to evaluate the marginal fit of copy-milled Celay In-Ceram crowns after different fabrication steps and to compare light-microscopic with scanning-electron-microscopic data. A master steel die of an upper middle incisor with a shoulder preparation and a rounded inner line angle was used. Impressions were taken to produce 10 working stone dies. One crown per working die was manufactured. The evaluation of the external marginal gap was performed on the master steel die by using a light microscope and a computerized video image analysis system after copy milling (A), glass infiltration (B), and veneering (C). Approximately 3900 readings were taken. In a final series the veneered crowns were measured by using a scanning electron microscope (Cs), yielding approximately 1000 readings. The results obtained were: A mean, 25.1 microm; s.d., 5.1 microm; range, 2.5-76.8 microm: B mean, 20.6 microm; s.d., 2.3 microm; range, 2.5-76.1 microm: C mean, 18.3 microm; s.d., 4.1 microm; range, 2.5-87.2 microm: Cs mean, 23.0 microm; s.d., 7.6 microm; range, 0.0-94.5 microm. The results were statistically evaluated using the t-test. The differences found between the series did not show practical relevance. Therefore, it is concluded that the manufacturing steps after copy milling have no obvious influence on the external marginal gap width. Scanning electron microscopic data seem to confirm the light-microscopic results. Hence, we expect that the Celay In-Ceram method yields a clinically acceptable marginal fit.

Titanium requires special ceramic systems for veneering. This study compared the three-point bending strength of three commercially available titanium ceramic systems with a NiCr-alloy with conventional ceramics. Three-point bend specimens 25 x 5 x 0.5 mm were cast from polyethylene patterns. After alpha-case removal, they were veneered with 8 x 5 x 1 mm of ceramics at the center of the bar. Specimens were tested in a universal testing machine without ageing, after thermocycling, and after 90 d storage in an electrolyte solution. Titanium-ceramic systems were found to have a significantly lower bond strength in comparison to the NiCr-ceramic system. One of the titanium ceramic systems had a significantly lower bond strength in comparison to the other systems investigated. It could be concluded that bonding between titanium and ceramics is obtainable; however, the achievable bonds strengths did not match the NiCr-ceramic control.

The aim of the present study was to evaluate the clinically relevant properties of the recently introduced ceramic material IPS Empress, which is marketed for all-ceramic restorations. The following parameters were investigated: three- and four-point bending strength, bi-axial flexure strength, compressive and diametral tensile strength, compressive strength and marginal fit of full crowns. The results show that this material is a highly developed glass-ceramic with physical properties making this dental material well suitable for adhesively luted restorations.