Detecção de trincas em ápices radiculares após crioterapia com nitrogênio líquido in vitro, utilizando tomografia computadorizada de feixe cônico

Abstract

Cryotherapy with liquid nitrogen (N2) has been shown to be effective in eliminating microorganisms such as Enterococcus faecalis, but its use in parendodontic surgeries is still uncertain because its effects on dental tissues are not well established. This in vitro study evaluated the formation of cracks in root apices submitted to cryotherapy with liquid N2, using Cone Beam Computed Tomography (CBCT). Forty uniradicular human teeth were submitted to rotatory instrumentation, sealed, apicectomized, retroprepared and submitted to 02 applications of liquid N2. CBCT images of the root apices before and after cryotherapy were evaluated for the presence and number of complete, incomplete and intradentinal cracks. Data were submitted to the McNemar and Wilcoxon tests (p <0.05). The McNemar non-parametric test results showed a significant increase in the number of teeth with complete cracks from 45% to 75% after cryotherapy (p = 0.017). The number of teeth with incomplete and intradentinal cracks increased from 20% to 22.5% and from 15% to 25%, respectively, but with no statistical difference. Before cryotherapy, the detected mean was 0.575 cracks (± 0.747), and after the use of liquid N2 of 1.408 (± 0.904) cracks, the difference being significant (p = 0.000), by virtue of the increase in the number of complete cracks. A statistically significant difference was observed in the number of complete cracks in the following apical millimeters after apicectomy: "1.01 to 2mm" (p = 0.005), "2.01 to 3mm" (p = 0.023), "4.01 to 5mm" (p = 0.020). It was concluded that the use of liquid N2, not root apex, increase the number of root canals, and its indication as a coadjuvant in parendodontic surgeries for the elimination of microorganisms in persistent apical infections is not safe.