Pre-cementation procedures' effect on dental zirconias with different yttria content.

Objectve: Several pre-cementation procedures have been advocated to enhance adhesion between zirconia and resin-based cement. There is, however, limited documentation on how these pre-treatments affect the strength of zirconia crowns as most tests are performed on discs or bars. The aim was to assess the effect of pre-cementation procedures on fracture mode, fracture strength and cement retention on zirconia.

Comparison of sandblasted, ground and melt-etched zirconia crowns regarding adhesion strength to resin cement.

The aim is to compare the adhesion between zirconia and cements attained with melt-etching with potassium hydrogen difluoride, KHF, with that found when such traditional surface treatments as sandblasting and ceramic stone grinding are employed. Groups of zirconia crowns where treated by sandblasting ( = 6), grinding with carbide bur ( = 6) or melt-etching with KHF ( = 6) of the surface before cementation with a resin cement to an implant substitute made by Selective Laser Melting of a cobalt-chromium alloy. Tensile testing was performed to rupture, while measured increasing load at the zirconia-cement interface.

Debonding mechanism of zirconia and lithium disilicate resin cemented to dentin.

To evaluate debonding mechanism of zirconia and lithium disilicate cemented to dentin mimicking what could occur in a clinical setting. A null hypothesis of no difference in tensile bond strength between groups of zirconia and lithium disilicate cemented with resin cements was also tested. Zirconia rods ( = 100) were randomly assigned to two different surface treatment groups; air borne particle abrasion and hot etching by potassium hydrogen difluoride (KHF).

A novel etching technique for surface treatment of zirconia ceramics to improve adhesion of resin-based luting cements.

Bonding of zirconia crowns and bridges to abutments is important, not only bonding of the thin resin layer to the abutment, but also bonding to the zirconia ceramic is crucial. Both mechanical and chemical adhesion are desired. Mechanical retention of dental porcelain achieved by etching with moderately concentrated hydrofluoric acid is not possible with zirconia ceramics.

Load at fracture of monolithic and bilayered zirconia crowns with and without a cervical zirconia collar.

Statement Of Problem: The effect of anatomic contour design in all or parts of zirconia crowns is uncertain regarding clinical reliability and survival rates.

Purpose: The purpose of this in vitro study was to compare the load at fracture of monolithic, anatomic contour zirconia crowns with bilayered crowns with and without a cervical zirconia collar.

Material And Methods: Thirty zirconia crowns were fabricated for a shallow chamfer molar preparation, 10 with a normal core-veneer design, 10 with a core-veneer design with an additional cervical collar of zirconia, and 10 with a monolithic, anatomic contour design.

The Effects of Margin Curvature on Load at Fracture of Ceramic Crowns.

Purpose: Despite the high fracture strength of modern dental core ceramics, fractures are a common cause of clinical failures. The aim of this study was to use a clinically relevant test method to evaluate the effect of the curvature of the cervical crown margins on load at fracture.

Materials And Methods: Thirty zirconia crowns and 30 glass-ceramic crowns were produced for three premolar preparations with variation in the approximal crown margin curvature: low curvature (r=12 mm), moderate curvature (r=2.

Simulation of clinical fractures for three different all-ceramic crowns.

Comparison of fracture strength and fracture modes of different all-ceramic crown systems is not straightforward. Established methods for reliable testing of all-ceramic crowns are not currently available. Published in-vitro tests rarely simulate clinical failure modes and are therefore unsuited to distinguish between the materials.

Solubility and strength of zirconia-based dental materials after artificial aging.

Statement Of Problem: Advanced high-strength dental ceramics based on zirconium oxide are widely used for dental restorations. However, their durability in liquids has been questioned.

Purpose: The purpose of this study was to compare the flexure strength of zirconium dioxide materials designed for different sintering techniques before and after surface exposure to an acidic solution and to correlate the dissolution of the materials with strength data.

Clinically relevant fracture testing of all-ceramic crowns.

Objectives: Fracture strength measured in vitro indicates that most all-ceramic crowns should be able to withstand mastication forces. Nevertheless, fractures are one of the major clinical problems with all-ceramic restorations. Furthermore, the fracture mode of all-ceramic crowns observed in clinical use differs from that found in conventional fracture strength tests.

Bond strength of a composite luting agent to alumina ceramic surfaces.

Objective: The purpose of this study was to evaluate the shear bond strength (SBS) of a dental luting agent to alumina ceramics after different surface pretreatment.

Material And Methods: Specimens (n=50) of pressed blocks (10 x 0 x 5 mm) of alumina ceramic (Procera AllCeram) were divided into untreated specimens (AF) as provided by the manufacturer and polished specimens (AP). Five groups of specimens (n=5 x 10) with different surface pretreatments were prepared.

Bond strength of composite luting cement to zirconia ceramic surfaces.

Objectives: To evaluate the bond strength of dental resin agent to zirconia ceramic after surface pre-treatment with different techniques.

Methods: Specimens of hot isostatic pressed yttrium-oxide-partially-stabilized zirconia blocks (ZF) were fabricated (Procera Zircon, Nobel Biocare, Sweden) and compared to glossy dense zirconia blocks (ZG). Four groups of specimens with different surface treatment were prepared.