Comparison of Maximum rate of acute inflammation in periapical region of cat's preinfected teeth, following instrumentation of root canal with different preparation techniques

The aim of this study was to determine the maximum amount of acute inflammation in the periapical region of cat's preinfected canine teeth, following instrumentation of root canals with standard Profile (performed with double-Z method), Step-Back (with K-type file) and Crown-Down (with Nitiflex file) preparation techniques. Method & Material: 30 mature and healthy cats were selected and after cutting the crown of 3 of its canine teeth and removing the pulp and opening a path from the oral cavity to the periapical region (with over-instrumenting the canal with small-sized files), 48 hours later, the crownless canine teeth were randomly instrumented with Standard Profile, Crown-Down (using Nitiflex file) and Step-Back (using K-type file) techniques and the fourth tooth was left intact as the negative control group. After the instrumentation process was finished, depending on the group the cat was randomly assigned to, vital perfusion operation was performed 8, 24 and 48 hours later. Then the teeth with its surrounding tissue were resected and sent to lab for decalcification and staining processes and then the samples were examined under a light microscope. Statistical analysis was performed using Kruskal-Wallis test. 48 hours after removing the pulp and linking the periapical tissue to oral cavity via canal system and then instrumentation of the canal using the techniques evaluated in this study, the least inflammation was obtained in 48-hour group after the instrumentation was completed, comparing to 24 and 8-hour groups although this difference was significant only in the edema index (P<0.1). Maximum amount of acute inflammation after pulp expiration is seen 48 hours after it and then, the inflammation decreases in the preapical region in a way that during 48 to 96 hours after expiration, least amount of inflammation is seen in hour 96.