Effectiveness of Parameters in Quantifying Root Canal Morphology Change after Instrumentation with the Aid of a Microcomputed Tomography

Abstract

The objective of this study was to analyse the effectiveness of some parameters which characterise the change in morphology in human root canals subjected to ProTaper rotary enlargement with the help of an X-ray microfocus computed tomography (MCT) and to introduce a novel parameter that is effective in quantifying changes in root canal morphology. Ten each straight and curved root canals with mature apices chosen from extracted human upper incisor and canine teeth were scanned with MCT before and after canal shaping using ProTaper rotary instruments in order to facilitate three-dimensional digital reconstruction and quantitative gauging of relevant instrumental parameters and changes therein (surface area and volume). Root canal geometry change and the effectiveness of shaping were quantified with Structure Model Index change (ΔSMI) and surface area change to volume change ratio (ΔSA/ΔV). These two parameters were also tested on simulated canals. Postinstrumentation cross-sectional changes were also analysed, but only on the plastic blocks. Statistical analysis of parameters was carried out to verify the significance of results. Analysis of cross-sectional shape of postinstrumented resin simulated canals showed statistically significant decrease in Form Factor (p<0.05) and statistically significant increase in Eccentricity (p<0.005). ΔSMI did not show significant difference between straight and curved canals. SMI values showed bidirectional change during root enlargement which questions the reliability of this metric in analysing instrumentation. Statistically significant (p<0.005) deviations in ΔSA/ΔV were quantified as 1.92 and 3.22 for straight and curved human canals, respectively. Instrumentation-induced canal geometry change was determined to be more pronounced in curved canals using the novel parameter ΔSA/ΔV. This has been proven as being a statistically accurate and reproducible parameter for quantitative characterisation of root canal geometry change and differentiation of preparational efficacy for both straight and curved root canals.

Influência do grau de curvatura radicular na obturação de canais radiculares de molares

“…Os presentes resultados demonstram que o g rau de cu r vat u ra rad icu la r i n f luenciou significativamente na conicidade da obturação, visto que, quanto maior a curvatura radicular, mais difícil é a obtenção de uma conicidade adequada. Em canais curvos, a ampliação do volume acompanhado do desenvolvimento de um formato cônico e a permanência da forma original do canal em sua posição original são mais difíceis de serem alcançadas, pois dependem não somente da intensidade da curvatura do canal radicular, como também da cinemática de emprego dos instrumentos, sua flexibilidade e diâmetro, técnica de instrumentação, entre outros fatores [25].…”

Microcomputed tomographic evaluation of 6 NiTi files on the pericervical dentin and the smallest dentin thickness zones in mesial root canals of mandibular molars: an in vitro study

“…The calculation of surface and volume was repeated, pairing areas of interest, cross-section by crosssection, to verify all the processes [17,18,[22][23][24]. The variations were analyzed in the 2D and 3D geometry of the PCD area of the root canals, quantifying the changes in volume, dentin removed, surface, structure model index (SMI), convexity, and structure thickness index by subtracting the instrumentation outcome values per canal from the values registered during the initial scan for the same root canal [14,24]. CTAn v.1.20.8 software (Bruker micro-CT) was used to analyze the centering ability at the PCD portion of the root canal based on changes in the centers of gravity x, y, and z in millimeters, before and after, and per scanned slide [25,26].…”

“…Microcomputed tomographic technology allows a more precise structural and anatomical study of the root canal system, as the high resolution of the 3D images permits the collection of a signi cant volume of information, with minimum sample size, no destruction of the specimens, and faster analysis of the data with the use of computer tools integrated into the micro-CT device [14,15]. The present study aimed to evaluate and juxtapose the changes produced by WG, RB, TS, XP, IR, and TN in the PCD area of the root canals according to the amount of dentine removed, changes in the canal surface, structure thickness, structure model index (SMI), and centering ability as well as the changes in relation to the dentin removed in the STDZ at the cervical and middle third of the mesial root canals in mandibular molars.…”