Análise de três tipos de instrumentação na modelagem de canais radiculares de incisivos laterais superiores permanentes: estudo com controle da variação da anatomia do canal radicular

Abstract

Nickel-titanium (NiTi) files are the most suitable for modeling root canals, but there are no studies on permanent maxillary lateral incisors (ILSP). The objective of this in vitro study was to test the hypothesis that the type of instrumentation (NiTi files, in motorized modes and with a new manual adapter, and conventional stainless steel files) affects the shaping of permanent maxillary lateral incisor root canals (ILSPs). ). ) when the anatomical variation of the root canal (estimated by canal angulation, initial root canal volume and ratio between largest and smallest diameter) is controlled in data analysis. 60 upper lateral incisor teeth without endodontic treatment, without restoration, without root carious lesion and with apical angulation between 10° and 30° were selected based on 3D microcomputed tomography (MicroCT) and then randomly distributed into three groups (n = 20/group): NiTi files with motor (GMT), NiTi files with manual adapter (GAD) and conventional files (GAI). Each tooth was instrumented in two sequential steps, the first with files up to #45 (GMT45, using WaveOne Gold files; GAD45, using WaveOne Gold files and GAI45, using stainless steel files) and the second with files up to 80 (GMT80, using MKLife files; GAD80, using MKLife files; and GAI80, using stainless steel files). MicroCT analysis was performed after each instrumentation step and the following steps were analyzed in the apical third: volume increase (AVOL%), surface area increase (ASUR%), structure model index (SMI), areas not touched (ANT%), canal transport and frequency of apical defects. Then, the regression test was applied between confounding variables or covariates and the factor and stage, separately. For the development of the untouched area, the potential confounder or covariate was the mean AR variable. For the volume increase stage, the potential confounder or covariate was adjusted initial volume. AVOL% was strongly associated with the initial canal volume in all groups (coefficient r2 = 0.75-0.86, p< 0.01), so that the adjusted AVOL% (AVOLaj%) was obtained by the product of AVOL% by the logarithm of the initial volume. There was a lower AVOLaj% in the GAI45 and GAI80 groups when compared to the GMT45 (p = 0.03) and GMT80 (p = 0.02) groups, respectively, with no significant differences between the other groups. The same occurred with the increase in surface area, which had a strong negative association with the initial volume, and the increase in adjusted surface area (ASajus) was calculated by the product between the increase in surface area and the logarithm of the initial channel volume. . Regarding the frequency of apical errors, the GAI45 group had more errors than the GAD45 group (p = 0.03; Relative risk of 4.50; 95% CI: 2.62- 7.74) and the GAI80 group had more errors than the GMT80 (p = 0.02; Relative risk of 2.60; 95% CI = 1.11-6.08) and GAD80 (p = 0.01; Relative risk of 3.25; 95% CI = 1,44-7,35). In conclusion, the files showed lower adjusted volume than the motorized NiTi files and also a higher frequency of apical defects when compared with the motor and ED File groups, while the motorized and manual adapter NiTi file groups demonstrated similar performances at all stages.