The effect of aging on the accuracy of marginal adaptation and fracture resistance of CAD/CAM PEEK single crown restoration

Aim: In recent years, great advances have been made in the use of CAD/CAM to prepare fixed restorations. The marginal and internal fit of these restorations is a principal determinant for their clinical success. In addition, the nature of the oral environment affects the mechanical properties of these restorations. Therefore, this study aimed to investigate the effect of aging process under conditions that simulate the oral environment on the marginal adaptation, and, fracture resistance of crowns fabricated from polyether ether ketone (PEEK) using CAD/CAM methods. Methods: Twenty identical crown restorations were fabricated by using CAD/CAM methods to mill polyether ether ketone (PEEK) material. These crowns were produced by using a software design of an epoxy resin replica of the prepared maxillary first premolar tooth. All PEEK crowns were cemented and randomly divided into two equal groups (A, B). Each group was divided into subgroups (A1, A2 and B1, B2). Group A1 and A2 were used to measure marginal adaptation and fracture resistance, respectively, before aging, while group (B1 and B2) were measured after aging. The cemented crowns were mounted in resin molds to facilitate the sectioning process. The measurements of the marginal gap were performed after sectioning at four points using a stereomicroscope. The fracture resistance of the crowns was investigated using a universal testing machine. A statistical analysis was performed using the GraphPad Prism® software version and unpaired Student's t-test. Results: The results revealed that aging affected the marginal gap, and the fracture resistance of the PEEK crowns. While aging, negatively affected the conditions under investigation, however the least significant difference of marginal gap was found in the margin region. Conclusions: PEEK-CAD/CAM is considered as a good alternative prosthodontic material for fixed prostheses. The CAD/CAM technique used to make PEEK crown restorations in our study offers the advantages of high marginal accuracy and fracture resistance for long-term performance in the oral environment

Resistência flexural de uma resina para impressão 3D comparada a resinas acrílicas convencionais empregadas para confecção de placas estabilizadoras de mordida / Flexural resistance of 3D printing resin compared to conventional acrylic resins employed to build occlusal bite splints

Introduction: with the technological advance in dentistry, light-polymerized three-dimensional (3D) printing resins had become an alternative for the manufacture of occlusal splint splints. Objective: the present study aimed to analyze the flexural strength of a resin for 3D printing compared to conventional acrylic resins (chemically activated and thermally activated), under the influence of thermocycling. Material and method: 60 specimens were made, which were distributed in six experimental groups (n = 10), according to the resin employed (chemically activated acrylic resin, thermally activated acrylic resin and 3D printing resin) and the treatment received (control and thermocycling). The specimens were submitted to flexural strength by the three-point flexural test. Result: data analysis showed that the material factor (<0.0001) and the thermocycling factor (p = 0.0096) influenced flexural strength, however, the interaction between the two factors did not (p = 0.9728). Conclusion: it was concluded that 3D printing resins presented the lowest flexural resistance to acrylic resins, especially when submitted to thermocycling.

Introdução: com o avanço tecnológico dentro da odontologia, as resinas fotopolimerizáveis para impressão tridimensional (3D) se tornaram uma alternativa para a fabricação de dispositivos interoclusais. Objetivo: o presente trabalho teve como objetivo analisar a resistência flexural de uma resina para impressão tridimensional comparada com resinas acrílicas convencionais (quimicamente ativada e termicamente ativada), sob a influência da termociclagem. Material e método: foram confeccionados 60 corpos de prova, que foram distribuídos aleatoriamente em seis grupos experimentais (n=10), de acordo com a resina utilizada (resina acrílica ativada quimicamente, resina acrílica ativada termicamente e resina para impressão 3D) e com o tratamento recebido (controle e termociclagem). Os corpos de prova foram submetidos ao ensaio de flexão de três pontos para determinação da resistência flexural. Resultado: a análise dos dados demonstrou que o fator material (<0.0001) e o fator termociclagem (p=0.0096) influenciaram a resistência flexural, entretanto, a interação entre os dois fatores não (p=0.9728). Conclusão: deste modo podemos concluir que a resina para impressão 3D apresentou desempenho inferior às resinas acrílicas, especialmente quando submetida a termociclagem.

Is the adhesive or mechanical behavior of glass ceramics influenced by the adhesive layer application after etching and silanization? A literature review

Aim: This review investigated the effect of applying an adhesive after surface treatment of glass-ceramics on the bonding, mechanical or clinical behavior. Methods: Studies comparing the adhesive, mechanical or clinical behavior of glass-ceramics, with or without adhesive application after surface treatment, were included. Searches were performed in PubMed, Scopus, and Web of Sciences databases (January 2022), resulting in 15 included studies. Results: Regarding the evaluated outcomes, 13 studies assessed bond strength, 2 studies assessed biaxial flexural strength and 1 study assessed fatigue failure load, while no study evaluating clinical outcomes was included. It was possible to observe that the adhesive application after ceramic surface treatment was unfavorable or did not influence the evaluated outcomes. Conclusion: Most of the evidence available in the literature shows that the adhesive application after surface treatment does not improve the adhesive and mechanical behavior of glass-ceramics

Influence of substrate, cement and aging on the biaxial flexural strength of lithium disilicate / Influência do substrato, cimento e envelhecimento na resistência a flexão biaxial do dissilicato de lítio

Objective: To evaluate the biaxial flexural strength (BFS) of lithium disilicate (L), cemented on different substrates (epoxy resin - E and metal - M) with dual-cure resin cement (Rc) and zinc phosphate cement (Zc), not aged, thermally aged (TC) or thermo-mechanical aged (TC/MC). Material and Methods: Disks of L, E, and M were fabricated, and the cementation was performed according to the following groups: ERc (L+E+Rc); MRc (L+M+Rc); MZc (L+M+Zc); EZc (L+E+Zc). Ten samples from each described group were tested in BFS, ten more samples were subjected to TC (1×104 cycles between 5 ºC and 55 ºC water), and the last 10 samples were subjected to TC/MC (MC: 1.2×106 cycles, 50 N, 3.8 Hz). The BFS test was performed and scanning electron microscopy (SEM) was performed to evaluate the failure mode. The effect of the cementation strategy (cement/substrate) was compared in each aging method and the effect of the aging method was evaluated for each cementation strategy by one-way ANOVA and Tukey post-hoc test (α=0.05). Results: The strength values were highest to M (237.8 ~ 463.9 MPa), in comparison to the E (41.03 ~ 66.76 MPa), despite aging and luting agent. Flexural strength data decreased after TC and TC/MC in groups cemented with Zc, but was stable when cemented with Rc. SEM analysis indicated that failure origins were located at the tensile surface of the L. Conclusion: Lithium disilicate discs cemented to the metallic substrate presented the highest biaxial flexural strength. The cementation with dual-cure resin cement did not decrease BFS after aging (AU)

Objetivo: Avaliar a resistência à flexão biaxial (BFS) do dissilicato de lítio (L), cimentado sobre diferentes substratos (resina epóxi - E e metal - M) com cimento resinoso dual (Rc) e cimento de fosfato de zinco (Zc), não envelhecido, submetido ao envelhecido térmico (TC) ou ao envelhecido térmico-mecânico (TC/MC). Material e Métodos: Foram confeccionados discos de L, E e M, e a cimentação foi realizada de acordo com os seguintes grupos: ERc (L+E+Rc); MRc (L+M+Rc); MZc (L+M+Zc); EZc (L+E+Zc). Dez amostras de cada grupo descrito foram testadas em BFS, mais dez amostras foram submetidas à TC (1×104 ciclos de imersão em água entre 5 ºC e 55 ºC), e as últimas 10 amostras foram submetidas à TC/MC (MC: 1.2 ×106 ciclos, 50 N, 3.8 Hz). Foram realizados os testes de BFS e a microscopia eletrônica de varredura (MEV) para avaliar o modo de falha. O efeito da estratégia de cimentação (cimento/substrato) foi comparado em cada método de envelhecimento e o efeito do método de envelhecimento foi avaliado para cada estratégia de cimentação por ANOVA a um fator e teste post-hoc de Tukey (α=0,05). Resultados: Os valores de resistência foram maiores para M (237.8 ~ 463.9 MPa), em comparação com E (41.03 ~ 66.76 MPa), independentemente do envelhecimento e do agente cimentante utilizado. Os dados de resistência à flexão diminuíram após TC e TC/MC nos grupos cimentados com Zc, mas se mantiveram estáveis quando cimentados com Rc. A análise MEV indicou que a origem das falhas estava localizada na superfície de tração do L. Conclusão: Os discos de dissilicato de lítio cimentados ao substrato metálico apresentaram maior resistência à flexão biaxial. A cimentação com cimento resinoso dual não diminuiu o BFS após o envelhecimento (AU)

Influence of number and position of porcelain specimens in the furnace on flexural strength and translucency

The aim of this study was to investigate the influence of the quantity and positioning of feldspathic ceramic specimens inside the furnace on their flexural strength and translucency. The tested hypotheses were that the arrangement of specimens in the furnance would not influence 1) the translucency or 2) the biaxial strength of the porcelain. Methods: Ninety porcelain specimens were made (1.2 mm thickness and 13.5 mm diameter) and assigned into two main groups (n=15): G1 group - 15 firing cycles containing only one specimen each, always at the center of the refractory; and G5 group - 15 firing cycles containing five specimen each, where one specimen was at the center of the refractory and four specimens positioned equidistantly on the periphery. The translucency test was performed using a spectrophotometer, followed by the flexural strength test, according to ISO 6872:2015. T-student test was performed for both the mechanical and optical obtained data. Results: The flexural strength of the porcelain was not affected by the positioning (center x periphery) of the specimens inside the furnace (p =0.08), but the translucency was affected (periphery > center; p =0.009). Regarding to the number of feldspathic ceramic specimens, the biaxial flexural strength was affected (p =0.025), as well as the translucency (p <0.05). Conclusion: A higher quantity of feldspathic ceramic specimens for each firing cycle decreased its biaxial flexural strength and translucency. Also, specimens positioned at the center of the refractory became less translucent than those positioned at the periphery.

Flexural strength and Vickers hardness of milled and 3D-printed resins for provisional dental restorations

Various forms of temporary resins are offered on the market; however, the properties of temporary resins obtained by milling and 3D printing have not been fully examined. This study aimed to compare the flexural strength and Vickers hardness of milled and 3D-printed resins. Methods: Three resins were tested: Evolux PMMA (milled resin), Cosmos Temp (3D-printed resin), and Structur 2 SC (bis-acrylic resin, group control). Specimens were prepared with rectangular shapes (n = 12) for flexural strength measurements and disc shapes (n = 9) for Vickers hardness tests. Flexural strength tests were performed at a crosshead speed of 0.75 mm/min, and the Vickers hardness was measured under a load of 20 N for 10 s. The obtained data were subjected to the Kruskal­Wallis test. Results: A significant difference (p < 0.05) in flexural strength was observed among the three sample groups: Evolux PMMA (111.76 MPa), Structur 2 SC (87.34 MPa), and Cosmos Temp (56.83 MPa). No significant difference (p < 0.05) was observed between the Vickers hardness values of Structur 2 SC (33.37 VHN) and Evolux PMMA (29.11 VHN); however, both materials were statistically superior to Cosmos Temp (10.90 VHN). Conclusion: While the mechanical properties of the milled resin were superior or similar to those of the bisacrylic resin, the 3D-printed resin was statistically inferior to both the milled and bis-acrylic resins

Cigarette Smoking Effect on Microhardness and Flexural Properties of Denture Base Resins

ABSTRACT Objective: To identify the tobacco effect on flexural properties and the microhardness of three acrylic resins. Material and Methods: Three resins were tested: two thermo-polymerizable acrylic resins (RMB 20 and BMS 014) and one autopolymerized acrylic resin. The 3-point bending and microhardness tests were carried out with a universal tensile-compression machine and a micro-Vickers hardness tester. The acrylic resin specimens have been exposed for 21 days to cigarette smoke in a smoking room. Their mechanical strength was compared to unexposed samples. Statistical analysis was performed using the data processing software SPSS Statistics 21.0. Results: The flexural properties of the resins were affected by cigarette smoke only in the case of Major Base 20® (drop in strength with p= 0.02; 0.6; 0.7 and in elastic modulus with p= 0.86; 0.74 and 0.85 for Major Base 20®, BMS 014® and Major Repair®). The cigarette smoke affected significantly microhardness for all groups (p<0.001). Conclusion: Cigarette smoking does not affect the flexural properties of the acrylic resin (BMS 014® and Major Repair® unlike Major Base 20®), but it does reduce the microhardness.

Avaliação da resistência à fratura de dentes com fragilização simulada utilizando sistema de pinos de fibra de vidro / Fracture resistance evaluation of teeth with simulated embrittlement using fiberglass post system

O objetivo deste trabalho foi avaliar, ex vivo, pelo teste de compressão e ciclagem, a resistência a fratura de dentes que tiveram suas raízes fragilizadas em laboratório que receberam reforço intrarradicular com um modelo de pino de fibra de vidro Splendor-SAP em comparação ao pino de fibra de vidro Exacto. Além disso, foi realizada análise por elementos finitos para identificar os pontos de maior estresse estrutural. Foram utilizadas 60 raízes de dentes bovinos, os espécimes foram seccionados e padronizados com 16 mm de comprimento. Os canais foram instrumentados em toda a sua extensão utilizando limas endodônticas manuais. As amostras foram aleatoriamente distribuídas em seis grupos acordo com a espessura do remanescente radicular medidos a partir do terço cervical (2 mm e 3 mm) e o reforço radicular a ser utilizado (n=10): G1 - Controle 1, com remanescente radicular de 2 mm e sem reforço intrarradicular; G2 - Controle 2, com remanescente radicular de 3 mm e sem reforço intrarradicular; G3 - Com remanescente de 2 mm e reforço intrarradicular utilizando pino Exacto; G4 - Com remanescente radicular de 3 mm e reforço intrarradicular utilizando Exacto; G5 - Com remanescente radicular de 2 mm e reforço intrarradicular utilizando Splendor-SAP; G6 - Com remanescente radicular de 3 mm e reforço intrarradicular utilizando Splendor-SAP. Para a fragilização simulada, o desgaste radicular foi de 12 mm no interior do canal. Em seguida, os canais foram obturados e o material obturador removido dos terços cervical e médio, restando apenas 4 mm de material no terço apical. A cimentação dos pinos foi realizada seguindo o protocolo do fabricante. O teste de fadiga foi realizado por ciclagem mecânica dos espécimes para o envelhecimento das mesmas (1200000 ciclos; 3.8 Hz; carga = 88 N). Foi realizado o teste de compressão pela máquina de Ensaios Universais, com célula de carga de 100 Kg à velocidade de 1 mm/min com incidência a 45°. Os valores médios de resistência à fratura encontrados para os grupos, em ordem crescente, foram: G1 - 9,045 kgf, G2 - 9,753 kgf, G3 - 68,411 kgf, G4 - 80,167 kgf, G5 - 70,551 e G6 - 80,027. Os espécimes foram analisados em estereomicroscópio para classificação do modo de falha. Os resultados obtidos foram submetidos à análise estatística (ANOVA e Tukey) que demonstrou diferença estatisticamente significativa (p<0,05) (AU)

The objective of this work was to evaluate, ex vivo, by compression and cycling test, the resistance to fracture of teeth that had their roots weakened in the laboratory and that received intraradicular reinforcement with a Splendor-SAP fiberglass post model in comparison to the Exact fiberglass pin. In addition, finite element analysis was performed to identify the points of greatest structural stress. Sixty roots of bovine teeth were used, the specimens were sectioned and standardized with 16mm in length. The canals were instrumented along their entire length using manual endodontic files. The samples were randomly distributed into six groups according to the thickness of the root remnant (2 mm and 3 mm) and the root reinforcement to be used (n=10): G1 - Control 1, with a 2 mm root remnant and without intraradicular reinforcement ; G2 - Control 2, with root remnant of 3 mm and without intraradicular reinforcement; G3 - With a 2 mm remnant and intraradicular reinforcement using an Exacto post; G4 - With root remnant of 3 mm and intraradicular reinforcement using Exacto; G5 - With root remnant of 2 mm and intraradicular reinforcement using Splendor-SAP; G6 - With root remnant of 3 mm and intraradicular reinforcement using Splendor-SAP. For simulated embrittlement, root wear was 12 mm inside the canal. Then, the specimens were obturated and had the obturator material removed from the cervical and middle thirds, leaving only 4 mm of material in the apical third. The cementation of the posts was performed following the manufacturer's protocol. The fatigue test was carried out by mechanical cycling of the specimens for their aging (1200000 cycles; 3.8 Hz; load = 88 N). The compression test was carried out using the Universal Testing machine, with a load of 100 kg at a speed of 1 mm/min with an incidence of 45°. The average fracture resistance values found for the groups, in ascending order, were: G1 - 9,045 kgf, G2 - 9,753 kgf, G3 - 68,411 kgf, G4 - 80,167 kgf, G5 - 70,551 e G6 - 80,027. The specimens were analyzed under a stereomicroscope to classify the failure mode. The results obtained were submitted to statistical analysis (ANOVA and Tukey) which showed a statistically significant difference (p <0.05). (AU)

Efeito antimicrobiano e propriedades mecânicas da zircônia translúcida revestida por vidros experimentais / Antimicrobial effect and mechanical properties of translucent zirconia coated with experimental glasses

Objetivos: Avaliar as propriedades mecânicas, atividade antimicrobiana e citocompatibilidade da zircônia translúcida 5Y-PSZ revestida por vidros experimentais contendo boro e prata. Métodos: Discos 5Y-PSZ (KATANA UTML™, Kuraray Noritake) foram processados e divididos em quatro grupos: polido, sem nenhum revestimento (Controle), aplicação de glaze comercial (Glaze) e vidros experimentais contendo prata (AgCoat) e boro (BCoat). As amostras foram submetidas aos testes de dureza Vickers, testes de flexão biaxial, análise fractográfica e rugosidade através de perfilometria óptica. O potencial antimicrobiano foi caracterizado usando biofilmes de espécie única de Streptococcus mutans e Candida albicans. Foi realizada a quantificação de unidades viáveis formadoras de colônias (UFC), atividade metabólica (CV), ensaios de matriz polissacarídica extracelular (EPS) e biovolume. Biofilmes foram visualizados por microscópio eletrônico de varredura (MEV) e microscopia confocal de varredura a laser (CLSM). A citocompatibilidade foi determinada usando os testes WST-1 e LIVE&DEAD usando células-tronco do ligamento periodontal (PDLSCs) por 24 h. Todas as caracterizações biológicas foram realizadas em triplicatas técnicas e biológicas usando amostras independentes. As análises estatísticas foram realizadas por ANOVA de uma via, teste de Tukey, análise de Weibull e análise de correlação de Pearson. Resultados: BCoat, AgCoat e Glaze alcançaram dureza semelhante, que foi menor que o Controle. BCoat teve a maior resistência à flexão e parâmetros de Weibull (m = 11,5, sF 625 MPa, s0 620) seguido por AgCoat (m = 5,3; sF 464 MPa, s0 478 MPa). BCoat diminuiu significativamente a formação de biofilmes, conforme mostrado pela menor UFC (5,94 log-UFC/mm2) e atividade metabólica (0,17 a.u.) em comparação com os outros grupos (AgCoat: 6,44 log-UFC/mm2, 0,89 a.u.; Glaze: 6,81 log UFC/mm2, 1,21 a.u.; Controle: 6,82 logUFC/mm2, 1,25 a.u.). BCoat e AgCoat apresentaram os menores valores de EPS (0,11 a.u.), seguidos por Glaze e Controle (0,13 a.u.; 0,14 a.u., respectivamente). MEV e CLSM revelaram que os biofilmes no BCoat eram finos, esparsos, com menor biovolume, enquanto os outros grupos produziram biofilmes robustos com maior biovolume. Os ensaios de viabilidade celular não mostraram toxicidade para PDLSCs para todos os grupos. Conclusão: 5Y-PSZ revestida por vidro experimental contendo boro surge como uma estratégia potencial para melhorar as propriedades mecânicas e antimicrobianas do material (AU).

Objectives: To evaluate the mechanical and antimicrobial properties of boroncontaining coating on translucent zirconia (5Y-PSZ). Methods: 5Y-PSZ discs (Control) were coated with a glaze (Glaze), silver- (AgCoat), or boron-containing (BCoat) glasses. The coatings' antimicrobial potential was characterized using S. mutans and C. albicans biofilms through viable colony-forming units (CFU), metabolic activity (CV), and the extracellular polysaccharide matrix (EPS). Biofilm architectures were imaged under scanning electron and confocal laser scanning microscopies (SEM and CLSM). Cytocompatibility was determined at 24 h via WST-1 and LIVE&DEAD assays using periodontal ligament stem cells (PDLSCs). The coatings' effects on mechanical properties were characterized by Vickers hardness, biaxial bending tests, and fractography analysis. Statistical analyses were performed via one-way ANOVA, Tukey's tests, Weibull analysis, and Pearson's correlation analysis. Results: BCoat significantly decreased biofilm formation, having the lowest CFU and metabolic activity compared with the other groups. BCoat and AgCoat presented the lowest EPS, followed by Glaze and Control. SEM and CLSM images revealed that the biofilms on BCoat were thin and sparse, with lower biovolume. In contrast, the other groups all yielded similarly robust biofilms with higher biovolume without compromising PDLSC viability. BCoat, AgCoat, and Glaze also presented similar hardness significantly lower than Control. BCoat had the highest flexural strength, characteristic strength and Weibull parameters (sF : 625 MPa; s0: 620 MPa; m = 11.5), followed by AgCoat (sF : 464 MPa; s0: 478 MPa; m = 5.3). Significance: BCoat is a cytocompatible glass with promising antimicrobial properties that can improve the mechanisms and reliability of 5Y-PSZ (AU).

Mechanical Properties of Mini-Implants Used in Extra-Radicular Anchorage

ABSTRACT Objective: To evaluate the mechanical properties of mini-implants (MIs) manufactured from stainless steel and compare them with conventional titanium-aluminum-vanadium alloy MIs. Material and Methods: The following groups were formed: G1 (n=24), 8×1.5 mm steel MIs; G2 (n=24), 12×2.0 mm steel MIs; and G3 (n=24), 10×1.5 mm titanium MIs. The 72 MIs were inserted in the infra zygomatic crest region of the maxilla and retromolar trigone in the jaw of 10 pigs. Pull-out, insertion torque, fracture and percussion tests were performed in order to measure the tensile strength, primary stability and fracture strength of MIs. A digital torque gauge was used to measure insertion and fracture torque, a universal mechanical testing machine was used for pull-out testing and a periotest device was used to measure the micromovement of MIs. For morphological and MI component evaluation, scanning electron microscopy (SEM) was performed. D'Agostino & Pearson, Kruskal-Wallis, and Dunn post-hoc and normality tests were used. Results: G2 insertion and fracture torques were significantly higher than G1 and G3 insertion and fracture torques (p<0.05). The pull-out and percussion tests presented similar values among the groups. SEM revealed that the fracture point was predominantly on the fourth thread for steel MIs (G1 and G2) and on the seventh thread for titanium-aluminum-vanadium MIs (G3). Conclusion: The mechanical properties of stainless steel MIs are superior to those of titanium-aluminum-vanadium alloy MIs.

Fracture strength and failure load of CAD/CAM fabricated endocrowns performed with different designs

Aim: Endocrown restorations are commonly used to rehabilitate endodontically treated posterior teeth and their use is well-founded in these cases. However, to date, there is little scientific evidence of their behavior in anterior teeth. The aim of this in vitro study was to evaluate the compressive strength of upper central incisors teeth, restored with glass-ceramic total crowns by the conventional anatomical core technique, and compare them to teeth restored with endocrowns with and without the presence of ferrule. Methods: Thirty teeth were randomly distributed into three groups: GE2 - endocrown group with 2 mm ferrule, GE0 - endocrown group without a ferrule, and GC - conventional crown with intraradicular post group. Crowns were cemented and teeth submitted to the 45o compression test until the fracture happened. Fractured specimens were analyzed to determine the fracture pattern. Descriptive analysis of the variables was performed and one-way analysis of variance was utilized to analyze the data for significant differences at p < 0.05. Results: The results of the control group (284.5 ± 201.05N) showed the highest fracture resistance value, followed by the 2mm group (274.54 ± 199.43N) and by the 0mm group (263.81 ± 80.05N). There was no statistically significant difference between all the groups (p = 0.964). Conclusions: The absence of a cervical enamel necklace favored a debonding of the pieces and endodontically treated anterior teeth could be restored with endocrown, which could be considered a conservative and viable treatment option

Influence of diameter on mechanical behavior of morse taper narrow implants

Dental implants could give back function, esthetics and quality of life to patients. The correct choice of the implant, especially in borderline cases, is essential for a satisfactory result. Aim: Thus, the objective of this study was to evaluate the mechanical behavior of Morse taper implants with two different prosthetic interfaces. Methods: Twenty self-locking Morse taper implants, 2.9 mm in diameter (FAC), and 20 Morse taper implants, 3.5 mm in diameter (CM) were divided into two groups (n=10), and submitted to strength to failure test, optical microscopic evaluation of fracture, metallographic analysis of the alloy, finite element analysis (FEA) and strain gauge test. A Student's t test (α = 0.05) was made for a statistical analysis. Results: For the strength to failure test, a statistically difference was observed (p <0.001) between FAC (225.0 ± 19.8 N) and CM (397.3 ± 12.5 N). The optical microscopic evaluation demonstrated a fracture pattern that corroborated with FEA ́s results. The metallographic analysis determined that the implants of the FAC group have titanium-aluminum-vanadium alloy in their composition. In the strain gauge test, there was no statistical difference (p = 0.833) between CM (1064.8 ± 575.04 µS) and FAC (1002.2 ± 657.6 µS) groups. Conclusion: Based on the results obtained in this study, ultra-narrow implants (FAC) should ideally be restricted to areas with low masticatory effort

Effect of frozen storage on preservation of a silicone-based test food material

Aim: This study aimed to evaluate the effect of frozen storage on the physical properties of a silicone-based test food material, highly used to evaluate the masticatory performance in research settings. Methods: A total of 1,666 silicone cubes of Optosil Comfort® with 5.6-mm edges were shaped and stored at -18°C. The cubes were subsequently tested for flexural strength (maximum force, displacement, stress, and strain) before breaking (n = 136), changes in weight and size (n = 170), and masticatory performance (n = 1360) at eight timepoints: immediately after cube preparation (baseline, no freezing), and 1, 2, 3 and 4 weeks, and 2, 4 and 6 months after frozen storage. The cubes were thawed 8 h before each assessment. Results: The maximum force, stress, maximum displacement, and deformation values for the cubes were not affected by freezing (P > 0.05). At all of the time points, the cubes exhibited similar weight (P = 0.366) and size (identical values). The masticatory performance for the cubes also showed no differences from baseline through 6 months (P = 0.061). Conclusion: Freezing Optosil Comfort® silicone cubes did not alter the physical and mechanical properties of the material, being suitable to optimize the assessment of masticatory parameters for research purposes

Resinas acrílicas utilizadas em placas estabilizadoras: resistência a fraturas e ensaio microbiológico / Acrylic resins used in stabilizer plates: resistance to fractures and microbiological testing

O aprimoramento da tecnologia CAD/CAM permitiu a confecção de placas estabilizadoras digitais, no entanto, há lacunas acerca do comportamento desses dispositivos frente a variáveis mecânicas e biológicas ainda desconhecidas. Dessa forma, o objetivo desse trabalho foi verificar se as resinas utilizadas na tecnologia digital das placas fresadas e impressas são capazes de influenciar na resistência à fratura e na adesão de micro-organismos em detrimento das resinas empregadas na confecção das placas termopolimerizáveis convencionais e se as propriedades testadas se relacionam com a variação da espessura desses dispositivos. Para tanto, foi realizado um estudo in vitro que contou com as fases mecânica e microbiológica, sendo cada uma composta pelos grupos Convencional (GC) (n=30), Fresado (GF) (n=30) e Impresso (GI) (n=30), de acordo com o método de confecção, possuindo cada um três subgrupos (n=10) que variaram a espessura dos espécimes de 1 a 3 mm. Na fase mecânica, as amostras, com formato de barras de 65 mm, foram testadas quanto à resistência à fratura na máquina de ensaios universal, com célula de carga de 500 kgf e velocidade de 1 mm/min; na microbiológica, a forma foi de discos com 15 mm de diâmetro, submetidos à adesão de micro-organismos à superfície com a exposição a Streptococcus mutans e mantidos por 24h a 35 °C em estufa para sucessiva contagem de UFC, com controle positivo. Os testes foram feitos em triplicata e os dados foram armazenados no SPSS 22.0 e a análise estatística contou com a ANOVA e o pósteste de Tukey. Nos resultados da fase mecânica, o ANOVA identificou diferenças estatisticamente significativas entre os grupos (p≤0,005), mostrando que GC e GF apresentaram melhores resultados. O pós-teste de Tukey considerou diferença estatisticamente significativa entre GF e GI (p=0,031), elencando GF como superior. Para a fase microbiológica, não foram verificadas diferenças estatísticas entre os grupos (p>0,005) em nenhuma das análises. Observou-se que para a resistência a fraturas, as resinas do modo fresado descreveram resultados superiores e/ou próximos aos da técnica convencional; e que as resinas da técnica digital e convencional, quanto à adesão superficial de micro-organismos, não diferiram entre si (AU).

CAD/CAM technology allowed the stabilizing splints manufacture, however there are gaps about these devices' behavior in face of mechanical and biological variables that are still unknown. Thus, the objective of this project was to verify if the resins used in digital technology of milled and printed stabilizer splints can influence fracture resistance and microorganism adhesion, in detriment of the resin applied in manufacture of conventional thermopolymerizable splints and if the tested properties are related to thickness variation of these devices. The method included mechanical and microbiological steps, each one composed by Conventional (CG) (n=30), Milled (MG) (n=30) and Printed (PG) (n=30) groups, according to the method of preparation, each one having three subgroups (n=10) that varied the specimen thickness from 1 to 3 mm. In the mechanical step, the samples, in the form of 65 mm bars, were tested for fracture resistance in a universal testing machine, with load cell of 500 kgf and speed of 1 mm/min; in the microbiological step, the shape was in form of 15 mm diameter discs, subjected to microorganism adhesion to the surface with exposure to Streptococcus mutans and kept for 24 hours at 35 °C in oven for successive CFU counting, with positive control. The tests were performed in triplicate and data were stored in SPSS 22.0 and statistical analysis used ANOVA and Tukey's post hoc. In the results of mechanical step ANOVA had identified statistically significant differences between the groups (p≤0,005), showing CG and MG had presented better results. Tukey´s post hoc had considered statistically significant difference between MG and PG (p=0,031), listing MG as superior. For the microbiological step, they did not show statistical differences between the groups (p>0.005) in any analysis. It was observed milled resins described superior results and/or close to the conventional technique one, for fracture resistance; and resins of digital and conventional technique, regarding the microorganism adhesion to the surface, did not differ from each other (AU).

Influência da angulação e espessura da camada de impressão na resistência à flexão, estabilidade dimensional e rugosidade de uma resina impressa / Influence of the angulation and thickness of the printing layer on the flexural strength, dimensional stability and roughness of a printed resin

Objetivo: Avaliar a influência da angulação e espessura da camada de impressão na resistência à flexão de três pontos (), estabilidade dimensional e rugosidade de uma resina provisória impressa. Metodologia: A partir da modelagem de uma barra (26 x 2,2 x 2,2mm) em software Meshmixer (Autodesk) e obtenção de arquivo STL, este foi exportado para o software da impressora 3D SLA (Forms2/Formlabs), onde 225 barras nas mesmas dimensões foram impressas com a resina Cosmos Temp, Yller (n=15) de acordo com os fatores "espessura da camada de impressão" (25µm;50µm;100µm) e "angulação" (0°; 30°; 45°; 60° e 90°). Após impressão, as amostras foram limpas com álcool isopropílico e encaminhadas ao pós-processamento em forno ultravioleta (Anycubic Wash e Cure Plus, Anycubic), por 15 minutos. As barras foram submetidas ao teste de  em máquina de ensaio universal (100KgF,1mm/min) e os dados (MPa) analisados com teste ANOVA 2 fatores, Tukey (5%) e análise de Weibull. Também foram realizadas as análises de rugosidade e estabilidade dimensional, cujos dados foram analisados pela ANOVA 2 fatores e Tukey (5%), além do MEV das superfícies. Resultados: Para a resistência à flexão, ANOVA 2 fatores revelou que o fator "Espessura da camada de impressão" (p<0,0001) foi estatisticamente significante, já o fator "Angulação" (p=0,8074) não apresentou significância estatística. Os grupos 30°/25µm (51,2±4,6AMPa), 60°/25µm (49,1±4,3ABMPa), 0°/25µm (48,6±6,6ABMPa), 90°/50µm (46,8±4,1ABCMPa) e 90°/25µm (46,2±4,9ABCMPa) apresentaram valores de  estatisticamente superiores aos grupos 0°/100µm (39,4±5,4DEFMPa), 60°/100µm (37,7±4,2DEFMPa), 90°/100µm (37,1±4,1EFMPa) e 30°/100µm (34,8±4,5FMPa), os quais foram semelhantes entre si. Para estabilidade dimensional, os grupos 0°/50µm (1746.9±61.80Aµm) e 0°/100µm (1704.7±84.30Aµm) apresentaram maiores alterações dimensionais, enquanto o grupo 90°/25µm (401.1±48.61Gµm) apresentou as menores alterações. Para rugosidade superficial, ANOVA relevou que os grupos 30°/100µm (0.90±0.10Aµm), 45°/100µm (0.79±0.07ABµm) e 60°/100µm (0.88±0.08Aµm) foram semelhantes entre si e apresentaram os maiores valores, enquanto a configuração 90°/100µm (0.23±0.08F) mostrou os menores valores. Conclusão: Quanto menor a espessura da camada de impressão, maior a resistência à flexão, independente da angulação escolhida. Adicionalmente, quanto menor a espessura da camada de impressão, maior foi a alteração dimensional, enquanto que objetos impressos verticalmente (90°) apresentam maior estabilidade dimensional. Para rugosidade superficial, quanto maior espessura da camada, maior rugosidade (AU).

Objective: To evaluate the influence of printing layer angulation and thickness on the three-point flexural strength (), dimensional stability and roughness of a printed provisional resin. Methodology: From the modeling of a bar (26 x 2.2 x 2.2mm) in Meshmixer software (Autodesk) and obtaining an STL file, it was exported to the SLA 3D printer software (Forms2/Formlabs), where 225 bars of the same dimensions were printed with Cosmos Temp resin, Yller (n=15) according to the factors "print layer thickness" (25µm;50µm;100µm) and "angulation" (0°; 30°; 45°; 60° e 90°). After printing, the samples were cleaned with isopropyl alcohol and sent to post-processing in an ultraviolet oven (Anycubic Wash and Cure Plus, Anycubic) for 15 minutes. The bars were submitted to the  test in a universal testing machine (100KgF,1mm/min) and the data (MPa) analyzed with 2-way ANOVA, Tukey (5%) and Weibull analysis. Roughness and dimensional stability analyzes were also performed, whose data were analyzed by 2- way ANOVA and Tukey (5%), in addition to the SEM of the surfaces. Results: For the flexural strength, 2-way ANOVA revealed that the factor "Print layer thickness" (p<0.0001) was statistically significant, while the factor "Angulation" (p=0.8074) did not show statistical significance. The 30°/25µm (51.2±4.6AMPa), 60°/25µm (49.1±4.3ABMPa), 0°/25µm (48.6±6.6ABMPa), 90°/50µm (46.8±4.1ABCMPa) and 90°/25µm (46.2±4.9ABCMPa) showed  values statistically higher than the 0°/100µm (39.4±5.4DEFMPa), 60°/100µm (37, 7±4.2DEFMPa), 90°/100µm (37.1±4.1EFMPa) and 30°/100µm (34.8±4.5FMPa), which were similar to each other. For dimensional stability, the 0°/50µm (1746.9±61.80Aµm) and 0°/100µm (1704.7±84.30Aµm) groups showed greater dimensional changes, while the 90°/25µm group (401.1±48.61Gµm) showed the smallest changes. For surface roughness, ANOVA revealed that the 30°/100µm (0.90±0.10Aµm), 45°/100µm (0.79±0.07ABµm) and 60°/100µm (0.88±0.08Aµm) groups were similar to each other and presented the highest values, while the 90°/100µm (0.23±0.08F) configuration showed the lowest values. Conclusion: The lower the printing layer thickness, the greater the flexural strength, regardless of the chosen angle. Additionally, the thinner the printing layer, the greater the dimensional change, while objects printed vertically (90°) have greater dimensional stability. For surface roughness, the greater the layer thickness, the greater the roughness (AU).

Transfixação horizontal de pino de fibra de vidro em um dente tratado endodonticamente: relato de caso clínico / Horizontal transfixion of a fiberglass post into an endodontically treated tooth: a clinical case report

O objetivo deste relato de caso foi descrever em detalhes a técnica de transfixação de pino de fibra de vidro no sentido horizontal e restauração de resina composta em um dente molar tratado endodonticamete. Paciente, sexo feminino, 51 anos de idade, buscou o Centro Universitário da Serra Gaúcha (FSG ­ Caxias do Sul ­ Rio Grande do Sul) com a necessidade de realizar tratamento endodôntico do elemento molar número 26. Após a avaliação inicial, foi realizada a endodontia. O elemento havia pouca sustentação das paredes vestibular e palatina, então foi proposto a colocação de pino intrarradicular seguido de coroa, entretanto, por questões financeiras a paciente não aceitou. Logo, foi proposto a técnica de transfixação horizontal de pino de fibra de vidro associado a uma restauração de resina composta de forma direta. O procedimento foi realizado em sessão única e foi utilizado um pino de fibra de vidro número 1 disposto transversalmente entre as paredes mesiopalatina e distovestibular. A restauração foi realizada com resina composta Filtek Z350, devolvendo estética e função ao elemento dentário. Pode-se concluir que a técnica de transfixação horizontal de pino de fibra de vidro associado à resina composta é uma alternativa restauradora que possibilita maior resistência aos dentes tratados endodonticamente, apresenta resultados funcionais e estéticos satisfatórios, além de possibilitar uma maior sobrevida aos mesmos(AU)

The purpose of this case report was to describe in detail the technique of horizontal transfixion of a fiberglass post into an endodontically treated tooth. Female patient, 51 years old, sought the University Center of Serra Gaúcha (FSG - Caxias do Sul ­ Rio Grande do Sul) with the need to perform the endodontic treatment of molar element number 26. After the initial evaluation, endodontics was performed. The element had little support for the buccal and palatal walls, so an intraradicular postplacement followed by a crown was proposed, for financial reasons the patient did not accept it. Therefore, the technique of horizontal transfixion of a fiberglass pin was proposed, associated with a restoration of direct composite resin. The procedure was performed in a single session and a number 1 fiberglass post was fixed crosswise between the mesiopalatal and distobuccal walls. The restoration was carried out with composite resin Filtek Z350, restoring aesthetics and function. It can be concluded that the horizontal transfixion of a fiberglass post associated with composite resin technique is a restorative alternative that allows greater resistance to endodontically treated teeth, provides satisfactory esthetics and better survival rates(AU)

Influência da espessura de restaurações cerâmicas a base de dissilicato de lítio para reabilitação oclusal de dentes posteriores: revisão de literatura / Influence of the thickness of lithium disilicate-based ceramic restorations for occlusal rehabilitation of posterior teeth: literature review

Reabilitações estéticas e funcionais são tratamentos realizados com bastante frequência na clínica diária do Cirurgião Dentista. Para tais intervenções existem diversos materiais citados na literatura, dentre eles, amálgama, ligas metálicas, resinas compostas e cerâmicas odontológicas. As cerâmicas apresentam inúmeras vantagens que integram estética e resistência, além de adesão aos tecidos dentários, todavia é alvo de uma vasta discussão a respeito de sua resistência mecânica quando se trata de trabalhos minimamente invasivos. A utilização das restaurações cerâmicas em dentes anteriores, submetidos a estresse mecânico reduzido, quando em condições oclusais satisfatórias, é vastamente citada na literatura, inclusive em espessuras extremamente conservadoras. Entretanto, quando se trata de dentes posteriores, onde as cargas oclusais são aumentadas, a espessura torna-se fator preponderante na utilização de tais materiais. Para esclarecer tais dúvidas, o presente estudo tem como objetivo realizar uma revisão da literatura a respeito da influência da espessura das cerâmicas a base de dissilicato de lítio em dentes posteriores na resistência a fratura de tais restaurações. Foi realizado levantamento bibliográfico de artigos publicados nas bases de dados PubMed, Lilacs, Medline, Scielo e Portal de Periódicos CAPES nos últimos 10 anos e, após a leitura dos resumos, selecionados os artigos presentes nesse trabalho. Conclui-se que cerâmicas a base de dissilicato de lítio de espessuras reduzidas devem ser utilizadas em dentes posteriores com cautela, haja vista a importância do equilíbrio oclusal e dos possíveis hábitos parafuncionais muito frequentes nos nossos pacientes.

Aesthetic and functional rehabilitations are treatments performed quite frequently in the daily clinic of the Dental Surgeon. For such interventions there are several materials cited in the literature, among them, amalgam, metal alloys, composite resins and dental ceramics. Ceramics have numerous advantages that integrate aesthetics and resistance, in addition to adhesion to dental tissues, however, it is the subject of a vast discussion regarding their mechanical resistance when it comes to minimally invasive works. The use of ceramic restorations in anterior teeth, submitted to reduced mechanical stress, when in satisfactory occlusal conditions, is widely cited in the literature, including in extremely conservative thicknesses. However, when it comes to posterior teeth, where occlusal loads are increased, thickness becomes a preponderant factor in the use of such materials. To clarify these doubts, the present study aims to review the literature regarding the influence of the thickness of lithium disilicate ceramics in posterior teeth on the fracture resistance of such restorations. A bibliographic survey of articles published in PubMed, Lilacs, Medline, Scielo and Portal de Periódicos CAPES in the last 10 years was carried out and, after reading the abstracts, the articles present in this work were selected. It is concluded that reduced thickness lithium disilicate ceramics should be used in posterior teeth with caution, given the importance of occlusal balance and possible parafunctional habits that are very common in our patients.

Braquetes cerâmicos fabricados por impressão 3D: ensaio mecânico de resistência à torção pela aplicação de torques / Ceramic brackets manufactured by 3D printing: mechanical test of torsion resistance by application of torques

A proposição deste estudo foi comparar a nova geração de braquetes personalizados cerâmicos impressos 3D Lightforce Clear , com os braquetes cerâmicos injetados Clarity e GC Chic em um ensaio mecânico de resistência à torção pela aplicação de torque. Amostras de braquetes cerâmicos impressos de alumina policristalina de incisivos centrais superiores (n=10), o Lightforce Clear (Lightforce Orthodontics), e os braquetes cerâmicos injetados de alumina policristalina, Clarity (3M Unitek) e GC Chic (GC Orthodontics) os quais foram submetidos ao teste de resistência à fratura torcional utilizando um segmento de fio de aço inoxidável 0,019 x 0,025 polegadas em uma máquina de ensaio universal (EMIC, DL-1000) à uma velocidade de 1mm/min e célula de carga de 1000 kg. Os resultados foram submetidos à análise estatística ANOVA fator 1. Os valores médios e desvio padrão obtidos no ensaio de resistência à torção de carga máxima de fratura (N) nos três grupos de bráquetes foram: 14,53 ± 2,85 para Lightforce Clear; 12,03 ± 2,44 para Clarity e 6,65 ± 0,35 para o CG Chic. Foi observado que houve diferença estatística significante entre os grupos testados (p<0,05). Os braquetes Lightforce Clear cerâmicos impressos 3D customizados mostraram-se mais resistentes que os injetados apontando como uma alternativa factível e promissora em busca de uma ortodontia digital de precisão contudo existe a necessidade de incorporar novas pesquisas para o avanço desta tecnologia (AU).

The purpose of this study was to compare the new generation of customized ceramic brackets 3D printed Lightforce Clear, with the injected ceramic brackets Clarity and GC Chic in a mechanical test of torsion resistance by the application of torque. Samples of ceramic printed polycrystalline alumina brackets of upper central incisors (n=10), Lightforce Clear (Lightforce Orthodontics), and the injected ceramic brackets made from polycrystalline alumina, Clarity (3M Unitek) and GC Chic (GC Orthodontics) which were subjected to torsional fracture strength testing using a 0.019 x 0.025-inch stainless steel wire segment in a universal testing machine (EMIC, DL-1000) at a speed of 1 mm/min and a load cell of 1000 kg. The results were submitted to ANOVA factor 1 statistical analysis. The mean values and standard deviation obtained in the maximum fracture load (N) torsional strength test in the three groups of brackets were: 14.53 ± 2.85 for Lightforce Clear; 12.03 ± 2.44 for Clarity and 6.65 ± 0.35 for CG Chic. It was observed that there was a statistically significant difference between the groups tested (p<0.05). The customized 3D printed Lightforce Clear ceramic brackets proved to be more resistant than the injected ones, pointing as a feasible and promising alternative in the search for precision digital orthodontics, however there is a need to incorporate new research to advance this technology (AU).

Fatores relacionados à fratura de dentes tratados endodonticamente / Factors related to fracture of treated teeth endodonticly

A longevidade de dentes tratados endodonticamente é um assunto amplamente discutido no campo de atuação da odontologia restauradora e envolve questões que vão além do alcance da endodontia. Não são raras as situações em que um dente reabilitado após a terapia endodôntica apresenta fratura corono- radicular, podendo comprometer sua viabilidade. Considerando o custo biológico envolvido na perda dentária, ou o custo material empregado para que os tratamentos sejam refeitos, é importante que os cirurgiões dentistas estejam capacitados a traçar o adequado plano de tratamento. O planejamento restaurador representa divergências de opinião, tanto na prática clínica quanto em âmbito científico, considerando-se as variáveis envolvidas como perda estrutural, ausências dentárias, posicionamento do dente no arco, número e localização das cúspides perdidas, presença ou não de retentor intra-radicular, representam papel importante na longevidade do tratamento restaurador e devem ser individualmente analisadas. Diante do cenário descrito, o objetivo deste estudo foi avaliar os fatores relacionados à fratura de dentes tratados endodonticamente. Através dessa revisão da literatura, conclui-se que a variável estrutural, relacionada à sua função mastigatória é a principal responsável no prognóstico dos dentes tratados endodonticamente. Por este motivo deve ser prioritariamente considerada ao se eleger o procedimento restaurador. É de extrema importância que a comunidade de cirurgiões dentistas disponha de conhecimento técnico e científico atual para pautar suas escolhas na prática clínica, embasando a análise individual do planejamento restaurador dos dentes tratados endodonticamente.

The longevity of endodontically treated teeth is a widely discussed subject in the field of restorative dentistry and it has issues that go beyond the scope of endodontics. It is not uncommon for a tooth rehabilitated to present a crown-root fracture, which may compromise its viability, after endodontic therapy. Considering the biological cost involved in tooth loss, or the material cost used for treatments to be redone, it is important that dental surgeons are able to draw up the appropriate treatment plan. Restorative planning still represents differences of opinion, both in clinical practice and in the scientific field, considering the variables involved such as structural loss, dental absences, tooth positioning in the arch, number and location of lost cusps, presence or not of intraretainer. -radicular, among countless other clinical variables, play an important role in the longevity of the restorative treatment and must be individually analyzed. The aim of this study was to evaluate the factors related to the fracture of endodontically treated teeth. Through this literature review, we concluded that the structural variable, related to its masticatory function, is the main responsible for the prognosis of endodontically treated teeth. For this reason, it should be considered as a priority when choosing the restorative procedure. It is extremely important that the community of dental surgeons have current technical/scientific knowledge to guide their choices in clinical practice, basing the individual analysis of the restorative planning of endodontically treated teeth.

Influência do tipo de impressão, do pós processamento e do tipo de resina na resistência à flexão e na estabilidade dimensional de resinas impressas / Influence of the type of printing, post processing and type of resin on the flexural strength and dimensional stability of printed resins

Avaliar a influência de diferentes protocolos de pós processamento e do tipo de impressão 3D na resistência a flexão de três pontos () e estabilidade dimensional de diferentes resinas impressas. Metodologia: A partir da modelagem de uma barra (26 x 2,2 x 2,2mm) em software Meshmixer (Autodesk) e obtenção de arquivo STL, este foi exportado para os softwares das impressoras 3D SLA (Forms 2/Formslab) e LCD (FlashForge Foto 6.0/ FlashForge). Em seguida, 45 barras de cada tipo de resina (Pr - Provisório/Cosmos Temp, Yller; Pl - Placa oclusal/Cosmos Splint, Yller; Mo ­ Modelos/ Cosmos Model, Yller) foram impressas por cada sistema de impressão (SLA e LCD). Após a impressão, as barras de cada tipo de resina foram limpas com álcool isopropílico e distribuídas aleatoriamente (n=15) de acordo com o fator de estudo: "Protocolo de pós processamento" Controle (C: sem pós processamento); Luz Ultravioleta (UV: 15 min em forno Anycubic Wash e Cure Plus, Anycubic) e Micro-ondas (M: 15 min em forno micro-ondas/1.400W). Após, as barras foram submetidas ao teste de  (100KgF, 1mm/min) e os dados (MPa) submetidos à ANOVA 2 fatores e Tukey (5%) para cada tipo de resina. Também foram realizadas as análises complementares de estabilidade dimensional (analisados pelos testes T pareado, ANOVA 2 fatores e Tukey 5%) e MEV das superfícies e fraturas. Resultados: Para a resistência à flexão da resina de modelo, ANOVA 2 fatores indicou que os fatores "Impressora" (p<0,0001) e "Pós processamento" (p<0,0001) apresentaram significância estatística. Os grupos SLAMUV (33.80±4.82AMPa) e LCDMUV (35.93±4.47AMPa) apresentaram maiores valores de , sendo superiores estatisticamente aos grupos sem pós processamento e pós processados em micro-ondas. Para os grupos de resina de provisório, ANOVA 2 fatores revelou que os fatores "Impressora" (p=0,0044) e "Pós processamento" (p<0,0001) apresentaram significância estatística. O grupo LCDPUV apresentou maior resistência à flexão (52,06±12.40AMPa), seguido de SLAPUV (42.86±2.09BMPa) e SLAPMO (26.73±5.48CMPa). Para os grupos de placa, ANOVA 2 fatores mostrou que os fatores "Impressora" (p<0,0001) e "Pós processamento" (p<0,0001) apresentaram significância estatística. O grupo LCDPLUV (91.46±12.33AMPa) apresentou o maior valor de resistência à flexão, sendo estatisticamente superior aos demais grupos. Para estabilidade dimensional, na resina de modelo, o teste T para amostras pareadas demonstrou que apenas as amostras impressas em SLA apresentaram uma alteração significativa da largura e espessura após os métodos de pós processamento. Para o comprimento apenas as amostras pós curadas em luz ultravioleta tiveram alterações significativas (p<0,05). Já com relação a resina para placas o grupo SLAPl-UV a apresentar maiores variações nas três dimensões analisadas (largura: -55,60Aµm; espessura: -12,80Aµm; comprimento: - 93,73Aµm), e por apresentar dados negativos sugere-se expansão do material. Com relação a resina para provisório, em todas as dimensões estudadas o grupo LCDProv-UV apresentou maiores alterações dimensionais (largura: 31,46Aµm; espessura: -28,40Bµm; comprimento: - 86,53Aµm), enquanto o grupo LCDProv-MO apresentou menores alterações (largura: -7,20 Bµm; espessura: -4,40 Aµm; comprimento:18,00Bµm). Conclusão: Pôde-se concluir que o pós processamento em luz ultravioleta promoveu os melhores valores de resistência à flexão para todos os tipos de resinas avaliadas, sendo a técnica de impressão LCD a que apresentou melhores valores de () quando associada ao pós processamento em luz ultravioleta, independente do tipo de resina. A estabilidade dimensional está associada ao tipo de resina e ao pós processamento utilizado (AU).

To evaluate the influence of different post-processing protocols and the type of 3D printing of different printed resins on the three-point bending strength () and dimensional stability. Methodology: A bar was modeled (26 x 2.2 x 2.2mm) on Mishmixer software and a STL file was obtained, the it was exported to the 3D printer software SLA (Forms 2/Formslab) and LCD (FlashForge Photo 6.0/ FlashForge). Then, 45 bars of each type of resin (Pr - Provisional/Cosmos Temp, Yller; Pl - Occlusal Plate/Cosmos Splint, Yller; Mo ­ Models/ Cosmos Model, Yller) were printed by each printing system (SLA and LCD). After printing, the bars of each type of resin were cleaned with isopropyl alcohol and randomly divided (n=15) according to factors: "Post-processing protocol" Control (C: without post-processing); Ultraviolet Light (UV: 15 min in Anycubic Wash and Cure Plus, Anycubic) and Microwave (M: 15 min in microwave oven/1,400W). Thein, the bars were submitted to the  test (100KgF, 1mm/min) and data (MPa) analyzed with 2-way ANOVA and Tukey (5%). Complementary analyzes of dimensional stability (analyzed by paired T tests and 2-way ANOVA) and SEM of surfaces and fractures were also performed. Results: For the flexural strength of the model resin, 2-way ANOVA indicated that the factors "Printer" (p<0.0001) and "Post processing" (p<0.0001) showed statistical significance. The SLAMUV (33.80±4.82AMPa) and LCDMUV (35.93±4.47AMPa) groups presented higher  values, being statistically superior to the groups without post-processing and microwave-processed powders. For the provisional resin groups, 2-way ANOVA revealed that the factors "Printer" (p=0.0044) and "Post processing" (p<0.0001) were statistically significant. The LCDPUV group showed the highest flexural strength (52.06±12.40AMPa), followed by SLAPUV (42.86±2.09BMPa) and SLAPMO (26.73±5.48CMPa). For the plate groups, 2-way ANOVA showed that the factors "Printer" (p<0.0001) and "Post processing" (p<0.0001) were statistically significant. The LCDPLUV group (91.46±12.33AMPa) presented the highest flexural strength value, being statistically superior to the other groups. For dimensional stability, on the template resin, the T-test for paired samples demonstrated that only the SLA printed samples showed a significant change in width and thickness after post-processing methods. For length, only the samples post-cured in ultraviolet light had significant changes (p<0.05). Regarding the resin for plates, the SLAPlUV group presented greater variations in the three dimensions analyzed (width: -55.60Aµm; thickness: -12.80Aµm; length: -93.73Aµm), and for presenting negative data, we suggest material expansion. Regarding the resin for provisional, in all dimensions studied, the LCDProv-UV group showed greater dimensional changes (width: 31.46Aµm; thickness: - 28.40Bµm; length: -86.53Aµm), while the LCDProv-MO group presented minor changes (width: -7.20 Bµm; thickness: -4.40 Aµm; length: 18.00 Bµm). Conclusion: It could be concluded that the post processing in ultraviolet light promoted the best values of flexural strength for all types of resins evaluated, being the LCD printing technique the one that presented the best values of () when associated with post processing in ultraviolet light, regardless of the type of resin. Dimensional stability is associated with the type of resin and post-processing used (AU).