The aim of this study was to evaluate and compare the resistance to fracture of interim restorations obtained through additive techniques (3D impressions) and subtractive techniques (milling) using a computer-aided design and manufacture (CAD/CAM) system of a three-unit fixed dental prosthesis (FDP) to ascertain its clinical importance. (1) Materials and methods: In total, 40 samples were manufactured and divided into two groups (n = 20) using: (1) light-curing micro hybrid resin for temporary crowns and bridges (PriZma 3D Bio Prov, MarketechLabs, São Paulo, Brazil) for the rapid prototyping group (RP) and (2) a polymethylmethacrylate (PMMA) CAD/CAM disc (Vipiblock Trilux, VIPI, São Paulo, Brazil) for the computer-assisted milling (CC). The resistance to fracture was determined with a universal testing machine. (2) Results: The strength and the standard deviation for the computer-assisted milling group were higher (1663.57 ± 130.25 N) than the rapid prototyping (RP) group, which had lower values of (1437.74 ± 73.41 N). (3) Conclusions: The provisional restorations from the computer-assisted milling group showed a greater resistance to fracture than the provisional restorations obtained from the rapid prototyping group.

The objective of the study was to evaluate the volumetric wear of four composite materials for CAD/CAM (computer-aided design/computer-aided manufacturing) systems. The materials evaluated were: Cerasmart (CER), Shofu Block HC (SBH), Tetric CAD (TEC) and Brava (BRA). All the samples (n = 40) were subjected to simulated brushing (100,000 cycles). Wear was evaluated by superimposing pre-and post-brushing scans obtained with an intraoral optical scanner (CEREC Primescan; Dentsply Sirona, Germany), which were subsequently imported into the OraCheck software 5.0 (Dentsply Sirona, Germany). The data were analyzed by ANOVA test and Tukey’s HSD test was used for multiple comparisons. Cerasmart showed the least wear after brushing. All the tested materials exhibited mass loss.

<p>Se han reportado un gran número de casos de descementación de postes de fibra de vidrio luego de su adhesión al conducto radicular.</p><p>El propósito de este estudio fue evaluar la eficacia de dos sustancias desinfectantes como Hipoclorito de Sodio (NaClO) 5.25%, y Clorhexidina 2% utilizadas como irrigantes antes de la cementación del poste de fibra de vidrio (PFV), en el proceso de adhesión-cohesión usando cemento dual (CD). Treinta dientes endodonciados, seccionados previamente sus coronas clínicas, fueron preparados para recibir cada uno un PFV.  Los cuerpos de prueba fueron divididos en tres grupos y se utilizó una técnica diferente de irrigación del conducto radicular: 1. NaClO al  5.25%. 2. Clorhexidina al 2% y 3. Agua. Los especímenes, fueron seccionados transversalmente con un disco de diamante en el tercio cervical (TC) y en el tercio medio (TM), obteniéndose 60 muestras para el estudio.</p><p>Se realizó la observación y medición al Microscopio Electrónico de Barrido (MEB) de las interfases cemento dual/dentina, (CD/D) y cemento dual/poste, (CD/P), tanto en su TM como en su TC, así como la medición del espacio existente en las interfases CD/D y CD/P de la superficie sin adhesión-cohesión.</p><p>El análisis de datos reveló una significancia en cuanto a la eficacia en relación al  porcentaje de adhesión en la interfase CD/D usando  NaClO al 5.25% en relación a la  Clorhexidina al 2% y Agua. No existiendo  diferencia significativa en el promedio del porcentaje de adhesión en el TC y en el TM. La técnica de irrigación con NaClO al 5.25% demostró ser la  que menor interferencia produjo en la interfase CD/D y CD/P presentando el mayor porcentaje de adhesión tanto en la interfase CD/D y cohesión en la interfase CD/P.</p>

Objectives: This study aimed to provide information on the accuracy of exported digital files with the different resolutions available in the CEREC 4.6.2 software obtained by means of an intraoral scanner (IOS), in addition to establishing differences between materialized models with different exported resolutions, and how these different exported files can influence finite element analysis (FEA) simulations. Materials and Methods:The upper complete arch of 10 patients was scanned through an IOS (CEREC Omnicam 1.0/Dentsply Sirona). Files of three resolution meshes digitalized by a CAD software (Cerec SW, 4.6.2) high, medium and low (IOSH, IOSM, and IOSL) were exported. Each file was evaluated by a software (NETFABB) about the number of triangles obtained and compared with the number announced by the manufacturer. Also, with a superimposition with a specialized software (GEOMAGIC X), the digital models were compared. The files of each resolution were printed (Sprintray 3D Printer), and the printed models were scanned with IOS (Omnicam 1.0) and compared with the control group (intraoral scanned high-resolution file, IOSH).FEA simulations were imported into COMSOL and analyzed under different loading conditions.Results: The number of exported triangles coincided with that reported by the manufacturer. The digital models from files of different resolution did not show significant differences (less than 1.5 um) between each other. Models printed (H, M, L) from files of the same resolution mesh (H, M, L) did not show significant differences between them either in partial measures of the arch and neither in the complete arch. FEA showed significant differences in stress concentration between different exported models.Clinical Significance: Digital models can be exported and printed in three resolutions of the mesh, without differences clinically significative. On the other hand, for future FEA applications further research should be performed in order to determine the optimal number of triangles.