In vitro failure of crowns produced by two CAD/CAM systems.
Previous laboratory studies have demonstrated satisfactory fracture resistance of all-ceramic crowns placed using a resin-composite luting material and a dentine bonding system. This study investigated the fracture resistance of teeth restored using CAD/CAM technology, namely, Zirconia Based crowns and Cerec produced feldspathic porcelain crowns, both luted with a self adhesive resin luting material (RelyX Unicem Clicker 3M ESPE). Standardized preparations were carried out on two groups often sound, unrestored, maxillary premolar teeth. Ceramic crowns were constructed to have a thickness of 2mm at their midline fissure. Compressive fracture resistance was determined for each group using a Universal Testing Machine. The failure modes were also examined visually and interpreted according to a chosen scale. Mean Compressive fracture resistance of 746 (147)N and 1630 (175)N were recorded for the Cerec and Lava groups respectively; differences were statistically significant (p < 0.001). The fracture resistance of teeth restored with Lava crowns is significantly greater than a similar group of teeth restored with Cerec crowns.
Primary Dental Care Research Group, University of Birmingham, School of Dentistry, College of Medical and Dental Sciences, UK.
Thomas J
TJ
Donnelly
F J Trevor
FJ
Burke
D000538:Aluminum Silicates / Q000737:chemistry; D001641:Bicuspid / Q000033:anatomy & histology; D019245:Compressive Strength; D017076:Computer-Aided Design; D003442:Crowns; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D003801:Dental Veneers; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D017680:Potassium Compounds / Q000737:chemistry; D019279:Resin Cements; D013314:Stress, Mechanical; D013499:Surface Properties; D019246:Tooth Preparation / Q000379:methods; D015040:Zirconium / Q000737:chemistry
D000538:Aluminum Silicates; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D017680:Potassium Compounds; C483701:Rely X Unicem; D019279:Resin Cements; C082340:Vita Mark II; D003776:Dental Porcelain; C016447:feldspar; D015040:Zirconium; C028541:zirconium oxide