Resumen La tomografía computarizada de haz cónico tridimensional (CBCT) tiene un papel importante en la detección de fracturas radiculares verticales (VRF). El efecto de la generación de artefactos por objetos de alta densidad como los implantes dentales en la calidad de la imagen está bien documentado. Este estudio tuvo como objetivo evaluar el efecto de la distancia entre el diente y el implante y la aplicación del algoritmo de reducción de artefactos metálicos (MAR) en la detección de VRF en escaneos CBCT. Este estudio se realizó en 20 dientes uniradiculares tratados endodónticamente. Se indujeron VRF en 10 dientes, mientras que los otros 10 permanecieron intactos. El implante se insertó en el área del alveolo del segundo premolar derecho, y dos dientes se insertaron en el canino derecho y en el área del alvéolo del primer premolar derecho al azar y se sometieron a CBCT con y sin la aplicación del algoritmo MAR. Se utilizó SPSS 21 para analizar los resultados (alfa=0,05). De acuerdo con los hallazgos de este estudio, las cuatro variables de sensibilidad, especificidad, precisión y valores predictivos positivos en el diagnóstico fueron más altas en los casos sin el software MAR tanto en distancias cercanas (raíces en las cavidades de los primeros premolares) como lejanas (raíces en las cavidades de los caninos) del implante. Sin embargo, la tasa más alta de precisión diagnóstica del primer y segundo radiólogo fue en el grupo de mayor distancia al implante sin MAR, y la tasa más baja de precisión diagnóstica en el primer y segundo radiólogo fue en la distancia cercana al implante. La aplicación del algoritmo MAR no tuvo un efecto positivo en la detección de VRF en escaneos CBCT en escenarios cercanos y distantes.

Abstract: Three-dimensional cone-beam computed tomography (CBCT) has an important role in the detection of vertical root fractures (VRFs). The effect of artifact generation by high-density objects like dental implants on image quality was well documented. This study aimed to assess the effect of tooth-implant distance and the application of metal artifact reduction (MAR) algorithm on the detection of VRFs on CBCT scans. This study was conducted on 20 endodontically treated single-rooted teeth. VRFs were induced in 10 teeth, while the other 10 remained intact. The implant was inserted in the right second premolar socket area, and two teeth were inserted in right canine and right first premolar sockets area randomly and underwent CBCT with and without the application of MAR algorithm. SPSS 21 was used to analyze the results (alpha=0.05). According to the findings of this study, all four variables of sensitivity, specificity, accuracy, and positive predictive values in diagnosis were higher in cases without MAR software at both close(roots in first premolar sockets) and far distances (roots in canine sockets) from the implant. However, the highest rate of diagnosis accuracy of the first and second radiologists was in the far distance group from the implant without MAR, and the lowest rate of diagnosis accuracy in the first and second radiologists was in the close distance to the implant. Applying MAR algorithm had no positive effect on detection of VRFs on CBCT scans in both close and distant scenarios.

RESUMO Introdução: muitos pacientes, ao buscar o tratamento ortodôntico, já apresentam lesões incipientes no esmalte e precisam ser submetidos a tratamentos preventivos. O objetivo do presente estudo in vitro foi avaliar o efeito da pasta CPP-ACP e da irradiação com laser de CO2 na microdureza do esmalte desmineralizado e na resistência ao cisalhamento de braquetes ortodônticos. Métodos: oitenta pré-molares humanos hígidos foram submetidos a desmineralização usando Streptococcus mutans. Após a desmineralização, as amostras foram divididas aleatoriamente em cinco grupos experimentais: Grupo 1 (controle), os braquetes foram colados sem qualquer tratamento de superfície; Grupo 2, a superfície do esmalte foi tratada com pasta CPP-ACP por 4 minutos antes da colagem; Grupo 3, os dentes foram irradiados com laser de CO2 no comprimento de onda de 10,6 µm, por 20 segundos; Grupos 4 e 5, as amostras foram tratadas com laser de CO2 antes ou durante a aplicação de CPP-ACP. Foram feitas fotomicrografias por Microscopia Eletrônica de Varredura (MEV) de um dente de cada grupo, para avaliação da superfície do esmalte. Os braquetes foram colados ao esmalte na face vestibular, usando-se o método convencional. Foram medidos a resistência ao cisalhamento dos braquetes e o escore do Índice de Adesivo Remanescente (ARI). A microdureza Vickers foi medida nas superfícies do esmalte onde não foi realizada colagem. Os dados foram analisados com ANOVA e teste Tukey ao nível de p< 0,05. Resultados: a média da força de resistência ao cisalhamento e da microdureza do grupo laser foi superior à do grupo controle, com diferença estatisticamente significativa (p < 0,05). Todos os grupos apresentaram maior porcentagem do escore ARI=4. Conclusões: o laser de CO2 no comprimento de onda de 10,6 µm aumentou significativamente a microdureza do esmalte desmineralizado e melhorou a adesão dos braquetes nele.

ABSTRACT Introduction: Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments. The aim of this in vitro study was to evaluate the effect of CPP-ACP paste and CO2 laser irradiation on demineralized enamel microhardness and shear bond strength of orthodontic brackets. Methods: Eighty caries-free human premolars were subjected to a demineralization challenge using Streptococcus mutans. After demineralization, the samples were randomly divided into five equal experimental groups: Group 1 (control), the brackets were bonded without any surface treatment; Group 2, the enamel surfaces were treated with CPP-ACP paste for 4 minutes before bonding; Group 3, the teeth were irradiated with CO2 laser beams at a wavelength of 10.6 µm for 20 seconds. The samples in Groups 4 and 5 were treated with CO2 laser either before or through CPP-ACP application. SEM photomicrographs of a tooth from each group were taken to observe the enamel surface. The brackets were bonded to the buccal enamel using a conventional method. Shear bond strength of brackets and ARI scores were measured. Vickers microhardness was measured on the non-bonded enamel surface. Data were analyzed with ANOVA and Tukey test at the p< 0.05 level. Results: The mean shear bond strength and microhardness of the laser group were higher than those in the control group and this difference was statistically significant (p< 0.05). All groups showed a higher percentage of ARI score 4. Conclusion: CO2 laser at a wavelength of 10.6 µm significantly increased demineralized enamel microhardness and enhanced bonding to demineralized enamel.