title: A study of the fracture resistance of nyyar cores of three restorative materials.
abstract: Despite the successful use of dental amalgam for coronal-radicular dowel and core build-up in endodontically-treated posterior teeth, newer materials offer many potential advantages over amalgam and have better patient acceptance. This study compared the fracture resistance of coronal-radicular restorations made from three different direct restorative materials. Sixty human premolars were selected, 45 of which were root treated and decoronated. Fifteen of these premolars were restored using amalgam, 15 with composite and 15 using resin-modified glass ionomer. The 15 unrestored teeth were used as a control group. All the teeth were mounted in acrylic within steel containers and subjected to compressive loading to failure on a universal testing machine. The force required to fracture each core specimen was recorded as well as the proportion of core lost due to failure. The results showed dental amalgam as having the highest fracture resistance (mean 1.93kN, sd 0.22) followed by resin-modified glass ionomer (mean 1.05kN, sd 0.20), sound tooth (mean 0.79kN, sd 0.20) and composite (mean 0.75kN, sd 0.11). The differences among all groups were significant. These results demonstrate that, although resin-modified glass ionomer is significantly weaker than amalgam, these restorations were stronger than unrestored teeth and failed at forces in excess of those encountered in normal mastication. Amalgam cores, along with resin-modified glass ionomer, tended to fail less catastrophically than the other materials and, given their strength, would remain the material of choice in situations where abnormally high forces are expected.
authors.affiliation: Dept of Restorative Dentistry, Leeds Dental Institute, Leeds, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Ferrier
authors.forename: Balraj S
authors.initials: BS
authors.lastname: Sekhon
authors.forename: Paul A
authors.initials: PA
authors.lastname: Brunton
mesh_terms: D001641:Bicuspid / Q000473:pathology; D001732:Bite Force; D003188:Composite Resins / Q000737:chemistry; D003723:Dental Amalgam / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D011176:Post and Core Technique; D019279:Resin Cements / Q000737:chemistry; D012390:Root Canal Therapy; D013314:Stress, Mechanical; D019553:Tooth, Nonvital / Q000628:therapy
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D005899:Glass Ionomer Cements; D019279:Resin Cements; D003723:Dental Amalgam