BackgroundThe association between the occurrence of microfractures and vertical root fractures has not been proven in published studies. One of the ways of trying to examine the influence of certain procedures on the resistance of the tooth to the action of occlusal forces is to subject the samples to fracture resistance testing by forces directed at the tooth or a specimen at different angles or by measuring that force on the root cross-sectional surface compressive strength.AimsThis study aims to examine dentinal resistance to compressive forces after root canal instrumentation with three different machine endodontics systems.Methods In order to examine the effect of instrumentation on the resistance of root dentin to the action of compression and compressive forces, teeth were divided in three groups and were instrumented with three different endodontics systems. The samples were subjected to compressive strength testing. Two forces were recorded: maximum force and breaking force.Results The results of the variance analysis show that there is no difference in breaking force between groups (p=0.151), but the difference is statistically significant between sections (p=0.001). The values of breaking forces in the cervical part are on average 25% lower.ConclusionWhen comparing the apical, medial and cervical part of the tooth, the medial part of the tooth has the highest values of breaking force and the apical part has slightly lower values. The values of breaking forces in the cervical part are on average 25% lower
