Effect of rotary endodontic instruments on tooth root dentinal microcracks formation

The importance of the problem and the aims of this study. The tooth root canals instrumentation is one of the most important step in endodontic treatment. There are many kinds of endodontic instruments systems currently in the market, which one from another differs in working principles, instrument design, alloy used to manufacture the instruments. When canals are being under the instrumentation, one of the most often tooth dentin damages are dentinal micro cracks which appear because of stress forces. Due of affect of occlusion and mastication forces, micro cracks are expanding and could cause vertical tooth root fracture, which determines tooth loss. Aims of the study: to determine rotary endodontic instruments ,,Protaper Next“, ,,Protaper Gold“, ,,XP-Endo Shaper“ impact microcracks formation in tooth root dentin. Materials and method: intact lower jaw incisors have been selected for this study. All teeth have been categorized into three experimental groups and one control group. For experimental groups teeth roots canals preparation were used endodontic instruments systems : ,,Protaper Next“, ,,Protaper Gold“, ,,XP-Endo Shaper“. To detect defect inside root dentinal micro cracks - tooth root sectioned method had been used. Statistic analysis has been done using a program SPSS Statistics 22.0. The difference of confidence level P<0,05 in experimental groups could be kept statistically significant. Results. The most micro cracks were found in experimental group ,,Protaper Next“ – 30 (53,6%), ,,Protaper Gold“- 15 (26,8%), ,,XP-Endo Shaper“- 7 (12,5%), in control group (K-file) - 4 (7,1%). Between experimental groups was determined statistically significant difference (P