Bond Strength Comparison of Three Core Build-up Materials Used to Restore Maxillary Incisor Teeth

The aims of this study were to examine the ultimate strength of the restored maxillary incisors with composite resin, dental amalgam and glassionomer cement as a transitional restoration. Fifty-six extracted human maxillary central incisors with intact and carious dentin were used. The control group consisted of eight unrestored teeth with intact dentin. Artificial defect in dentin was up to the half of the anatomic crown of the tooth. After core build-up procedure, each root of every specimen was mounted in autopolymerizing acrylic resin blocks which were stored in distilled water at 37°C one day before testing. Then it was placed in a specially adapted jig at an angle of 130 degrees to labio-palatal axis and subjected to a controlled load that was recorded in a universal testing machine at a crosshead speed of 1 mm per minute until failure occurred. There were no significant differences among control group and restored teeth with composite resin and dental amalgam with intact dentin (p<0.05). In the group with carious-affected dentin, there were no differences among restorative materials and the values were statistically significantly lower in comparison to the control group. Based on the date obtained, we concluded that the highest overall strength of restored incisors with intact dentin, when 50 per cent of the coronal part of the tooth is missing, was achieved by using composite resin and dental amalgam as a transitional restoration and as a core build-up material. The caries-affected dentin led to lower bond strength of restored teeth. Also it has been concluded that composite resin has the best bond and tensional strength ratio.