Accuracy assessment of different CBCT acquisition protocols used in rapid prototyping models

Abstract

This study compared the acquisition protocols of the Conical Beam Computed Tomography (CBCT) system, to assess the influence on image accuracy by different voxel sizes and the presence of soft tissue. Tomographic acquisition was performed in a fresh (F) and dry (D) pork jaw with voxel sizes of 0.4, 0.3 and 0.25 mm. The gold standard was obtained by scanning dry jaws covered with barium sulfate with a voxel size of 0.25 mm. The images were treated in the MIMICS® program, and noise areas were removed manually, using a fixed threshold for the purpose of generating 3D printing windows. Each window was virtually overlaid with the gold standard using the MeshLab software, obtaining absolute error values ​​between the meshes, generating a map of discrepancies. Significant differences were found between windows D 0.30 vs. F 0.30, D 0.30 vs. F 0.25, D 0.30 vs. D 0.25, D 0.30 vs. F 0.40, F 0.30 vs. D 0.25, F 0.25 vs. D 0.25, F 0.25 vs. D 0.40, D 0.25 vs. F 0.40, D 0.25 vs. D 0.40 and F 0.40 vs. D 0.40, (p <0.05). It was observed that the dry jaw windows showed a lower mean and standard deviation when compared to the fresh jaw windows. The 0.25 mm voxel protocol showed the most accurate result and the presence of soft tissues influenced the accuracy of the image when some protocols were compared statistically.

Uso de prototipagem rápida ou manufatura aditiva para estudos de casos clínicos e planejamento de técnica cirúrgica utilizando modelos 3D

“…As três tecnologias de impressão 3D mais conhecidas são a SLA, a Sinterização Seletiva a Laser ou Fusão (SLSselective laser sintering / SLMselective laser melting) e Modelagem de Deposição Fundida (FDMfused deposition modeling) (Silva et al, 2020). A prototipagem rápida passa por um processo sistemático necessitando de geometria espacial definida por modelos matemáticos feito por softwares do tipo CAD (computer-aided design) ou engenharia reversa, conversão em arquivo STL (surface tessellation language), transferência para o equipamento de impressão e sua manipulação, configuração dos parâmetros de impressão, remoção da peça, pós-processamento para intervenções adicionais como lixamentos adicionais e limpeza de acabamentos mais delicados (Chantarapanich et al, 2017;Corazza et al, 2020;.…”

“…A Manufatura Aditiva (MA) ou mais usualmente conhecida como impressão tridimensional (3D), é um processo de produção de objetos geométricos utilizando materiais (sintéticos ou orgânicos), que consiste na fabricação, a partir de um modelo tridimensional computadorizado, e exteriorizado por meio de impressoras que adicionam sucessivas camadas do material (Lozano et al, 2017;Volpato et al, 2017). Nada mais é do que a adição de camadas de um determinado material, de maneira automatizada que reproduz fisicamente um modelo 3D virtual (Corazza et al, 2020;Silva et al, 2020).…”

Morphometric bone assessment of men and women in different age range by cone beam computerized tomography

“…Cone beam computed tomography (CBCT) is an image exam with several clinical applications widely used in dentistry (Corazza et al, 2020;Marques et al, 2021;Pêgo et al, 2021) that provides a three-dimensional representation of the maxillofacial region with minimal distortion, image clarity, low cost and low radiation dose compared to other modalities of computed tomography, in addition to allow a qualitative and quantitative assessment of bone structures (Mostafa, Arnout & Abo El-Fotouh, 2016). It should be noted that the high visibility of the lower mandibular cortex in this imaging modality, favors the application of morphometric indices in all its extension through a dynamic evaluation (Alonso et al, 2016), indicating CBCT as an adjuvant diagnostic tool to refer patients at risk of osteoporosis to densitometric analysis.…”