Mechanical resistance of restored teeth with extensive crown damage

Introduction. Extensively damaged teeth can be restored by different core build-up materials. The aim of this study was to examine the mechanical properties of the restored maxillary premolars with composite resin, dental amalgam and glass ionomer cement (GIC) using compressive strength test. Materials and methods. Forty extracted intact human maxillary premolars were used in this study. Artificial defect in dentin was prepared using diamond bur up to the half of the anatomic crown of the tooth. After core build-up procedure, each tooth specimen was mounted in auto polymerizing acrylic resin blocks 2 mm below cement enamel junction and they were kept in distilled water at 37°C one day before testing. Then, they were placed in specially adapted devices at the angle of 183° to the longitudinal axis and subjected to a controlled load of 1 mm per minute. Results. Results showed that the best mechanical properties had samples restored with resin composite (492.5 N), then with amalgam (341.2 N) and glass ionomer cement (171.8 N). Comparing the fracture force using ANOVA, there was statistic significance between these groups (p<0.01). There were significant differences among control group and restored teeth with composite resin, amalgam and GIC. There was no significant difference in values of fracture forces between groups with composite resin and amalgam. The fracture force corresponding to the teeth restored with the GICs was significantly lower compared to the control group and the group with composite resin and amalgam. Conclusion. Satisfactory mechanical properties of restored premolars were obtained using composite resin and dental amalgam as a core build-up material.