FRACTURE RESISTANCE OF RESTORED MAXILLARY PREMOLARS
Extensively damaged teeth can be restored by different core build-up materials. The aim of this study was to examine the fracture resistance of restored maxillary premolars with composite resin, dental amalgam and glass ionomer cement (GIC) using compressive strength test. Also, to analyse the influence of bond strength of restorative materials on intact and carious dentin. Eighty extracted human maxillary premolars with intact and carious dentin were used in the study. The control group consisted of ten unrestored teeth with intact dentin. 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 specimen was mounted in auto polymerizing acrylic resin blocks 2mm below cement enamel junction and they were kept in distilled water at 37 oC one day before testing. Then, they were placed in specially adapted devices at an angle of 183o to the longitudinal axis and subjected to a controlled load of 1mm per minute. There were significant differences among control group and restored teeth with composite resin, amalgam and GIC. Results showed that the best fracture values were obtained in control group (749,4N , then intact teeth restored with composite resin (492,5N) and amalgam (341,2N). In the group with carious dentin, values were lower, for composite resin 345,5 N and for amalgam 474,5N. There were no significant differences among restored groups with intact and carious dentin (p<0.05). The fracture force corresponding to the teeth restored with GIC were significantly lower compared to the control group and the group with composite resin and amalgam. Satisfactory mechanical properties of restored premolars were obtained using composite resin and dental amalgam as a core build-up material. The carious-affected dentin led to lower bond strength of restored teeth.
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