Factors Influencing Vertical Radicular Fractures in Teeth Supported by Metallic Dental Core: A Scoping Review.

Purpose: The aim of this work is to conduct a literature review to highlight all the parameters involved in sub-prosthetic radicular fractures of teeth supported by metallic dental core. Materials and Methods: The following research was performed among published studies over the last 10 years in two PubMed/Medline and Scopus and supplemented by manual searching within the bibliographies. The search was restricted to publications in English and French. Results: Out of the 1464 articles initially identified, 18 studies met our inclusion criteria and were subsequently included in the literature review. These consisted of eight Finite Element Analysis Studies, two Retrospective Studies and one Randomized Controlled Trial. The results of this review show that radicular fractures are influenced by several variables, including predisposition, with maxillary premolars and mandibular molars being the most commonly affected teeth. Intracanal preparation can induce crack formation, leading to localized high stress concentrations. Increased ferrule height to 2 mm significantly enhances dental fracture resistance. Using high modulus of elasticity alloys results in nearly complete stress transmission to dentin due to their limited deformability and absorption capacity. The highest fracture resistance is achieved when posts are sealed using resin-modified glass-ionomer cement. Longer posts may be preferable to prevent vertical fractures. Additionally, occlusal factors, through repetitive stresses, contribute to crack propagation from surface defects, a phenomenon termed fatigue fracture. Conclusion: These findings have significant implications. Practitioners should be aware of the predisposition of certain teeth, the importance of preserving the ferrule effect, the choice of root post materials, post Cement Material and the role of occlusal forces in managing and preventing vertical root fractures.

Effect of Light Emission Through an Optical Fiber Device on the Bond Strength of a Hollow Experimental Intraradicular Post.

PURPOSE: To evaluate the effect of irradiation with an optical-fiber device on the bond strength of hollow and partially opaque intraradicular posts. MATERIALS AND METHODS: An optical-fiber accessory tip was attached to a light-curing unit to emit light through the central hollow of an experimental fiberglass post. The samples were divided into 4 groups (n = 80) according to the protocol (Variolink N [light cured] or Multilink N [dual-curing luting material]) and the light-curing mode (performed conventionally or with the optical fiber): GF: light-curing luting material; GFF: light-curing luting material and optical fiber; GD: dual-curing luting material; GDF: dual-curing luting material and optical fiber. The samples were tested immediately or after aging. Push-out bond strength, failure mode, degree of conversion (DC, assessed at the peak of 1750 cm-1), and stress distribution by finite element analysis were performed. Quantitative data were analyzed using 3-way ANOVA (luting material x light curing x depth) and 2-way ANOVA (aging x luting material), followed by Tukey's test. RESULTS: Bond strength was significantly affected by the luting material protocol (p < 0.001), depth (p = 0.010), and light curing mode (p = 0.031). The GFF group revealed higher bond strength in the middle and apical portions. The most frequent failure modes were adhesive in the apical portion for the GFF and GDF groups. The DC was higher for GF and GFF groups. CONCLUSION: Using the optical-fiber device led to superior bond strength results when a dual-curing luting material was used.

Influência da férula na resistência à fratura de restaurações com utilização ou não de retentores intrarradiculares em dentes tratados endodonticamente: uma revisão da literatura / Influence of the ferrule on the fracture resistance of restorations with or without the use of intraradicular posts in endodontically treated teeth: a literature review

Objetivo: realizar uma revisão de literatura narrativa sobre a importância e a influência do efeito férula na resistência à fratura de restaurações em dentes tratados endodonticamente com utilização ou não de retentores intrarradiculares. Metodologia: Foram utilizados os seguintes descritores indexados no DeCS (Descritores em Ciências da Saúde): "Férula", Prótese Dentária", "Falha da Restauração Dentária", "Técnica de Retentor Intrarradicular" e "Pinos de Retenção Dentária" para busca nas bases de dados PubMed, Embase, Lilacs, Web of Science, Scopus e Cochrane Library. Resultados: Os dados da maioria dos estudos in vitro ou in vivo incluídos nesta revisão sugerem o uso da férula para aumento da resistência à fratura e longevidade dos dentes tratados endodonticamente. Tem sido recomendada a confecção de uma férula com altura uniforme de 2 mm e espessura superior a 1,5 mm. Conclusão: O uso de retentores radiculares foi indicado pela maioria dos trabalhos, sendo geralmente recomendados os pinos de fibra de vidro ao invés de núcleos metálicos fundidos para minimizar os riscos de fratura radicular em razão do módulo de elasticidade semelhante à dentina, além de possibilidade de retratamentos em casos de falhas adesivas. Apesar disso, ainda são necessários estudos clínicos com acompanhamento a longo prazo para avaliar a longevidade das restaurações de dentes tratados endodonticamente utilizando pinos de fibra de vidro sem ou com a presença de férula em diferentes espessuras e alturas.

Objective: This study aimed to conduct a narrative literature review on the importance and influence of the ferrule effect on the fracture resistance of restorations in endodon-tically treated teeth with or without the use of intraradicular posts. Methodology: The following descriptors indexed in the DeCS (Health Sciences Descriptors) were used: "Ferrule", Dental Prosthesis", "Dental Restoration Failure", "Post and Core Technique", and "Dental Posts", to search on the databases of PubMed, Embase, Lilacs, Web of Science, Scopus, and Cochrane Library data. Results: Data from most of the in vitro or in vivo studies included in this review suggest the use of the ferrule to increase fracture resistance and longevity of endodontically treated teeth. It has been recommended to make a ferrule with a uniform height of 2 mm and a thickness greater than 1.5 mm. Conclusion: The use of intraradicular posts was indicated by most studies, and fiberglass posts are generally recommended instead of cast metal cores to minimize the risk of root fracture due to the modulus of elasticity similar to dentin, in addition to the possibility of retreatments in ad-hesive failure cases. Despite this, clinical studies with a long-term follow-up are essential to evaluating the longevity of restorations of endodontically treated teeth using fiberglass posts without or with the presence of ferrule in different thicknesses and heights.

Fracture toughness, vibration modal analysis and viscoelastic behavior of Kevlar, glass, and carbon fiber/epoxy composites for dental-post applications.

The use of flexible dental posts concentrates the stress at the dentin and the use of stiff posts increases the stress at the interface. Efforts were directed toward introducing inhomogeneous materials for resolving the disadvantages of both flexible and stiff posts. The main objective of this study was to develop three different fiber/epoxy composite posts. These composites were fabricated using carbon, glass, and Kevlar fibers. Characterization tests were conducted. In the tensile tests, the carbon, glass and Kevlar fiber composites exhibited tensile strengths of 200%, 91%, and 40% of the stainless-steel tensile strength, respectively, and exhibited stiffness values of 62%, 33%, and 12% of the stainless-steel stiffness. The carbon fiber/epoxy composite have a fracture toughness close to that of aluminum alloy. Vibration modal analysis indicated that the frequency response of the carbon fiber composite was lower than those of the glass and Kevlar composites. The highest tensile strength, storage moduli, and stiffness were recorded for the carbon fiber composites and the lowest were for Kevlar fiber composite. The low stiffness and strength of the Kevlar composite are attributed to the fact that Kevlar fibers had lower wettability with epoxy resin than both glass and carbon fibers. Moreover, the Kevlar fiber composite exhibited higher delamination. However, the stiffness and strength of Kevlar made its composite more sensitive than the other composites to free vibrations generated by a simple force induced by a hammer. Based on the results, the carbon fiber/epoxy composite has appropriate characteristics for application in new dental posts.

Evaluation of the effect of chlorhexidine and sodium hypochlorite in adhesive cementation of fiber posts - in vitro study / Avaliação do efeito da clorexidina e do hipoclorito de sódio na cimentação adesiva de pinos - estudo in vitro

Abstract Introduction The attachment of fiberglass posts is achieved through an adhesive process. Failures in adhesion may occur due to the hydrolytic degradation of the adhesives, or to the degradation of the collagen fibres of the hybrid layer by intrinsic enzymes. Objective To evaluate the effect of chlorhexidine and sodium hypochlorite treatment on bond strength to dentin. Material and method Thirty bovine roots were randomly distributed into 3 groups (n=10): a) Control, b) 2% Chlorhexidine, and c) 5% Sodium Hypochlorite. Next, RelyX® ARC resin cement was used to cement the post. Each specimen resulted in samples from the three root thirds that were submitted to the pushout test (MPa) at 24 hours and 12 months. Bond strength values were analysed using the Kolmogorov-Smirnov, 3-way ANOVA and Tukey tests. The fracture mode of the pin was also analysed using stereomicroscopy. Result There were no significant differences between treatments at the immediate time (p=0.0644) or in the interaction of factors (p=0.1935). After one year, the experimental groups showed no significant differences in bond strength in relation to the control group, with the exception of the cervical third of the chlorohexidine group in which there was a significant loss of adhesion. As for the fracture mode, there was a predominance of the mixed type in all groups and thirds. Conclusion The use of chlorhexidine or hypochlorite provides neither benefits nor losses in the adhesive bond strength of fiberglass posts. However, there is an influence of the root thirds, with the worst bond strength in the apical third.

Resumo Introdução A fixação de pinos de fibra de vidro é realizada através de um processo adesivo. Falhas podem ocorrer na adesão devido à degradação hidrolítica dos adesivos, ou pela degradação das fibras colágenas da camada híbrida por enzimas intrínsecas. Objetivo Avaliar o efeito do tratamento com clorexidina e hipoclorito de sódio sobre a resistência de união adesiva à dentina. Material e método Trinta raízes bovinas foram distribuídas aleatoriamente em 3 grupos (n=10): a) Controle, b) Clorexidina 2% e c) Hipoclorito de Sódio 5%. Após, para a cimentação do pino radicular, utilizou-se o cimento resinoso RelyX® ARC. Cada espécime resultou corpos-de-prova dos três terços radiculares, os quais foram submetidos ao teste de pushout (MPa) nos períodos de 24 horas e 12 meses. Valores de resistência de união foram analisados pelos testes de Kolmogorov-Smirnov, ANOVA (three-way) e de Tukey. Analisou-se ainda o modo de fratura do pino, através de estereomicroscopia. Resultado Não houve diferenças significativas entre tratamento no tempo imediato (p=0,0644) ou na interação dos fatores (p=0,1935). Após um ano, os grupos experimentais não promoveram diferença significante na resistência de união em relação ao controle, com exceção do terço cervical do grupo clorexidina, onde houve uma perda significativa de adesão. Quanto ao modo de fratura, houve predominância do tipo mista em todos os grupos e terços. Conclusão O uso de clorexidina ou hipoclorito não promove benefícios ou prejuízos na resistência de união adesiva de pinos de fibra, mas há influência dos terços radiculares, sendo a pior resistência de união no terço apical.

Radiographic analysis of 1000 cast posts in Sergipe state, Brazil / Avaliação radiográfica de 1000 retentores intrarradiculares metálicos fundidos no Estado de Sergipe

Introduction: Endodontically treated teeth with extensive coronary destruction require posts and cores to enable prosthetic restoration. Despite the increasing use of prefabricated posts, cast metal posts and cores are still widely used. The quality of the latter is important for the longevity of restorative treatment, and failure can occur if the fundamental principles are not followed. Objective: To radiographically evaluate the prosthetic principles of 1000 cast metal post-and-core restorations performed in single-rooted teeth and their coherence with the principles used for their confection. Material and method: Digital periapical radiographs of 1000 endodontically treated, single-rooted teeth with cast metal posts and cores were selected from the collection of a radiology clinic (Centro de Imagem, Aracaju/SE, Brazil). The images were analyzed using a measurement software (ImageJ, USA) in accordance with the fundamental prosthetic principles: length and diameter of the post, ratio between post and bone crest, contiguity of post to the root canal, gap between post and the remaining root canal filling, amount of remaining root canal filling, and absence of periapical lesion. The data were qualitatively analyzed, classified into ideal and not ideal, and submitted to the chi-square test (α=0.05). Result: Only 6.7% of the cast metal posts analyzed were satisfactorily fabricated. Conclusion: Many prosthetic criteria are neglected during the manufacturing of cast metal post and cores, resulting in inadequate work that may compromise the longevity of restorative treatments.

Introdução: Dentes com ampla destruição coronária e tratados endodonticamente necessitam de retentores intrarradiculares para viabilizar a restauração protética. Apesar do crescente uso de pinos intrarradiculares pré-fabricados, os retentores intrarradiculares metálicos fundidos ainda são muito utilizados. A qualidade desses é importante para a longevidade do tratamento restaurador, pois podem levar ao insucesso quando seus princípios fundamentais não são seguidos. Objetivo: Avaliar radiograficamente os princípios protéticos de 1000 retentores intrarradiculares metálicos fundidos em dentes unirradiculares e a coerência dos mesmos com os princípios para sua confecção. Material e método: Foram selecionadas radiografias periapicais digitais de 1000 dentes unirradiculares que receberam tratamento endodôntico e retentores intrarradiculares metálicos fundidos, através do acervo de uma clínica radiológica (Centro de Imagem, Aracaju/SE, Brasil). As imagens foram analisadas através de um software de mensuração (ImageJ, EUA) de acordo com os princípios fundamentais protéticos: comprimento e diâmetro do pino, relação do pino com a crista óssea, contiguidade ao canal, espaço entre o remanescente obturador e o pino, quantidade de material obturador e ausência de lesão periapical. Os dados foram tabulados, analisados qualitativamente em ideais e não ideais e submetidos ao teste do Qui-Quadrado (α=0,05). Resultado: Apenas 6,7% dos retentores intrarradiculares fundidos analisados foi confeccionado de forma satisfatória. Conclusão: Muitos critérios protéticos são negligenciados durante a confecção de retentores intrarradiculares metálicos fundidos, resultando em trabalhos inadequados que podem comprometer a longevidade do tratamento restaurador.

Detection of vertical root fractures in endodontically treated teeth in the absence and in the presence of metal post by cone-beam computed tomography.

BACKGROUND: Aim of this study was to investigate the influence of gutta-percha and metallic posts on the efficiency of Cone Beam Computed Tomography (CBCT) in diagnosing Vertical Root Fracture (VRF). METHODS: Forty-eight teeth were divided into 3 experimental and 3 control groups. The teeth of the first experimental group and the first control group received neither gutta-percha nor metal posts. The teeth of the second experimental group and the second control group were filled with gutta-percha, and the teeth of the third experimental group and the third control group were filled with the metal posts. The teeth of the experimental groups were artificially fractured. The teeth were evaluated through images taken by a Prexion scanner with a 0.1 mm resolution. Fisher's exact test was used to measure the following values: sensitivity, false negative, specificity, false positive and accuracy for the VRF detection through the scanner. Three observers calibrated and blinded to the protocol evaluated the images. RESULTS: The inter-observer Kappa coefficient was 0.83. The presence of posts and gutta-percha reduced the sensitivity and the accuracy in detecting the VRF. Regarding to the sensitivity (p = 0.837, p = 0.304, p = 0.837 for evaluator 1, 2 and 3, respectively) and specificity (p = 0.162, p = 0.056, p = 0.062 for evaluator 1, 2 and 3, respectively), Fisher's exact test showed no statistically significant difference among the evaluated groups. However, a significant difference was observed in relation to the accuracy in the results of evaluator 2 (p = 0.03), which showed a much lower accuracy for the post group (50 %) than for the Nonfilled group (93.8 %). CONCLUSIONS: The Prexion tomograph was precise in detecting vertical root fractures and the CBCT diagnostic ability was not influenced by the presence of posts or gutta-percha.

Influence of Relining Post on the Bond Strength of Resin Cements.

This study evaluated the influence of relining fiber posts on the bond strength (BS) of resin cements in the root canal. Forty bovine teeth were divided in four groups (n = 10): G1 (ARC)-fiber post cemented with resin cement RelyX ARC; G2 (ARC+Z350)-relined fiber post cemented with RelyX ARC; G3 (U200)-fiber post cemented with self-adhesive cement RelyX U200; G4 (U200+Z350)-relined fiber post cemented with RelyX U200. The roots were sectioned in six 1.2-mm slices and the push-out test was performed. Data were analyzed by three-way analysis of variance (ANOVA), and Tukey's test (a = 0.05). For the conventional resin cement, there was no significant difference between groups G1-ARC (15.5 ± 3.8) and G2-ARC+Z350 (16.1 ± 4.5). For the self-adhesive cement, the results revealed higher BS values for relined posts G4-U200 + Z350 (19.9 ± 7.9) as compared to non-relined posts G3-U200 (14.4 ± 4.5). For both cements, in groups of relined posts, the apical and the cervical thirds presented similar BS. Relining enhances the performance of the self-adhesive resin cement, and the interaction between relining and root third influences the BS to the conventional resin cement.

Bond strength of dual-cured resin cements to root canal dentin

Introduction: The bonding of dental posts to the root canal walls depends on the resin cement Objective:This in vitro study assessed the bond strength of resin cements used for post cementation to different root regions. Material and methods: Thirty canine roots were endodontically treated and prepared to receive dental posts which were luted with different resin cements (n = 10): Enforce (Dentsply), Panavia F (Kuraray Dental Co) and RelyX ARC (3M ESPE). The cements were light-cured for 20 s. After cementation, slices from cervical, middle and apical post/root regions were submitted to the push out test in a universal testing machine. The data (MPa) were analyzed using ANOVA and Tukey’s test (a = 0.05). Results: RelyX ARC (3.24 ± 1.49) and Enforce (3.45 ± 1.42) showed higher bond strength than Panavia (0.95 ± 0.39) (p < 0.05), without statistically significant difference between each other (p > 0.05). The bond strength values at the cervical (3.37 ± 1.47) were higher than middle (2.62 ± 1.94) and apical (1.65 ± 0.99) regions (p < 0.05), which were similar between them (p > 0.05). Conclusion: The resin cements RelyX ARC and Enforce presented greater bond strength than Panavia and the bond strength was higher at the cervical region.

Influence of luting agents on time required for cast post removal by ultrasound: an in vitro study

OBJECTIVE: This in vitro study evaluated the influence of luting agents on ultrasonic vibration time for intraradicular cast post removal. MATERIAL AND METHODS: After endodontic treatment, 30 roots of extracted human canines were embedded in resin cylinders. The post-holes were prepared at 10 mm depth and their impressions were taken using autopolymerizing acrylic resin. After casting procedures using a nickel-chromium alloy, the posts were randomly distributed into 3 groups (n=10) according to the luting material: G1- zinc phosphate (SS White) (control group), G2 - glass ionomer cement (Vidrion C; SS White), and G3- resin cement (C&B; Bisco). In G3, the adhesive procedure was performed before post cementation. After 24 h, the cement line was removed at the post/tooth interface using a fine diamond bur, and the ST-09 tip of an Enac ultrasound unit was applied at maximum power on all surfaces surrounding the posts. The application time was recorded with a chronometer until the post was completely dislodged and data were analyzed by ANOVA and Tukey's test (p<0.05). RESULTS: The roots were removed from the acrylic resin and inspected to detect cracks and/or fractures. The means for G1, G2, and G3 were 168.5, 59.5, and 285 s, respectively, with statistically significant differences among them. Two G3 posts resisted removal, one of which developed a vertical fracture line. CONCLUSIONS: Therefore, the cement type had a direct influence on the time required for ultrasonic post removal. Compared to the zinc phosphate and glass ionomer cements, the resin cement required a longer ultrasonic vibration time.

Avaliação das propriedades mecânicas e químicas em função de diferentes cimentos resinosos e pinos não-metálicos / Evaluation of the mechanical and chemical proprieties in different resin cements and nonmetallic posts

Este estudo objetivou: (1) testar a hipótese que a utilização de pinos nãometálicos em dentes tratados endodonticamente está associado a longevidade da restauração através de uma revisão sistemática; (2) avaliar o grau de conversão de dois cimentos resinosos em diferentes tempos após a fotoativação; (3) avaliar a resistência adesiva de diferentes cimentos resinosos usando dois pinos não-metálicos; (4) e avaliar a resistência a fratura e padrão de falha de dentes submetidos ao clareamento dental interno usando peróxido de hidrogênio a 35% restaurados com diferentes procedimentos. No artigo 1, 157 artigos participaram do estudo e após os critérios de inclusão-exclusão, restaram apenas 5 artigos. Para o artigo 2, vinte espécimes foram confeccionados para cada cimento, Panavia® F2.0 e RelyXTM Unicem Applicap. Cada espécime foi curado com luz LED e foram analisados imediatamente, 24 horas, 48 horas e 7 dias após a fotoativação. Os testes usados foram grau de conversão (FT-IR) e termogravimetria. No artigo 3, oitenta dentes pré-molares unirradiculares livres de coroas foram usados e divididos em 8 grupos: os pinos Exacto e Everstick foram cimentados com Breeze, Nexus 3, Panavia e Bistite. Os dentes foram obturados e preparados para cimentação dos pinos não-metálicos. Cada espécime foi perpendicularmente seccionado em aproximadamente 1 mm de espessura em 6 discos e divididos em região cervical, médio e apical. No artigo 4, oitenta dentes incisivos inferiores foram usados e metade foram clareados. Os dentes foram restaurados com resina composta, pinos de resina reforçado com fibra e pinos de fibra de vidro. Os pinos foram cimentados com Breeze e Panavia. Os espécimes foram submetidos ao teste de resistência a fratura pela máquina de testes universal. Todos os dados foram submetidos ao devido tratamento estatístico. Os pinos usados nos estudos selecionados do artigo 1 foram 52,5% pinos de fibra de quartzo, 13,2% pinos de fibra de vidro, 13,2% pinos de resina reforçada por fibra e 21,1% pinos de fibras de poletileno. Os dentes tiveram 96% de sobrevivência apos 2 anos e 94% em 8 anos. No artigo 2, o grau de conversão foi diferente estatisticamente entre 24 e 48 horas apos fotoativação para os dois cimentos e os maiores valores foi econtrado no cimento RelxYTM Unicem. No artigo 3, os pinos não tiveram diferença estatística significante na adesão quando comparados isoladamente, exceto para Bistite II DC. O Nexus 3 teve o maior valor e o Bistite II DC o menor. A prevalência de falhas adesivas entre o cimento e dentina foram encontrados. O artigo 4 mostrou nenhuma diferença estatística foi encontrado para a resistência a fratura e a fratura reparável foi a mais ocorrida (76,2%)

This study aimed: (1) To test the hypothesis that the placement of nonmetallic post in endodontically treated teeth is associated with improved survival rate of the restored teeth althouth systematic review; (2) to evaluate the degree of conversion of two resin cements in differents times after light-activated; (3) to evaluate the microtensile bond strength of different resin cement systems using two nonmetallic posts; (4) to evaluate the fracture resistance and failure pattern of endodontically treated teeth after intracoronal bleaching using 35% hydrogen peroxide with different restorative procedures. For the article 1, 157 papers were used and after the inclusion-exclusion procedure, only 5 papers remained. For the article 2, twenty specimens were made for each cement, Panavia® F2.0 and RelyXTM Unicem Applicap. Each specimen were cured with LED and were tested immediately, 24 hours, 48 hours and 7 days after light-activated. The tests used were degree of conversion (FT-IR) and thermogravimetric. For the article 3, eighty single-rooted human mandibular first premolar free crown were used and divided into 8 groups: Exacto and Everstick posts were cemented with Breeze, Nexus 3, Panavia F 2.0 and Bistite II DC. The teeth were obtured and prepared for cementation of the nonmetallic posts. Each specimen were perpendicularly sectioned into approximately 1 mm thick sections resulting in 6 serial slices and divided in cervical, meddium and apical region. For the article 4, eighty mandibular incisors were used and the half teeth were bleached. The teeth were restored with composite resin, fiber-reinforced composite post and glass fiber post. The posts were cemented with Breeze and Panavia. The specimens were submitted to the fracture resistance test by universal test machine. Statistical analyses were performed for each article. The posts used in the studies cited in article 4 were 52.5% quartz fiber posts, 13.2% glass fiber posts, 13.2% fiber-reinforced composite posts and 21.1% polyethylene ribbon posts. The survival rates ranged from 96% at 2 years to 94% at 8 years. The article 2, the degree of conversion was statistically different between 24 and 48 hours after light-activated for both cements and higher values were found for RelxYTM Unicem. The article 3, the nonmetallic posts had no statistical difference on bond strength when used the same resin cements, except Bistite II DC. The bond strength was highest for Nexus 3 and lowest for Bistite II DC. A prevalence of cement-dentin failures was found. The article 4 showed no statistically significance differences was found for the fracture resistance and the reparable teeth were the most frequently fracture mode occurred (76.2%)

Avaliação por microdureza Vickers da profundidade de polimerização de cimentos resinosos na cimentação de pinos de fibra de vidro empregando diferentes fontes de luz / Evaluation of Vickers microhardness on the curing depth of resin cements employed for luting of glass fiber posts with utilization of different light curing units

O objetivo desse estudo foi avaliar a microdureza Vickers de um cimento resinoso químico (C&B Cement - Bisco) e um de ativação dual (RelyX ARC ­ 3M ESPE), fotopolimerizado por diferentes fontes de luz, em função de diferentes profundidades do canal radicular, na cimentação de pinos de fibra de vidro. Os aparelhos fotopolimerizadores empregados foram: Optilux 360 (Demetron) - luz halógena; Radii (SDI) - LED; UltraLume 5 (Ultradent) ­ LED. Quarenta raízes de incisivos centrais inferiores bovinos tiveram seus condutos radiculares tratados endodônticamente previamente à cimentação de pinos de fibra de vidro Reforpost n0 3 (Ângelus), e foram divididas em quatro grupos de dez raízes cada, de acordo com o cimento resinoso e o aparelho fotopolimerizador utilizado para cimentação dos pinos: G1) All Bond 2 / C&B Cement, sem fotopolimerização (controle); G2) Scotchbond Multipurpose Plus (SBMP) + RelyX ARC, fotopolimerizado por luz halógena; G3) SBMP + RelyX ARC, fotopolimerizado pelo LED Radii; G4) SBMP + RelyX ARC, fotopolimerizado pelo LED UltraLume 5. Após 24 horas de armazenagem em água destilada à 370 C, as raízes foram seccionadas transversalmente, em três diferentes profundidades: 3.0mm; 6.0mm e 9.0mm, correspondendo aos terços: cervical, médio e apical do canal radicular. As medidas de microdureza Vickers foram obtidas 48 horas após a cimentação, realizando 12 endentações em cada secção radicular, na porção central do cimento ao redor do pino, com uma carga de 200g por 20 segundos. As médias de microdureza foram submetidas à Análise de Variância e Teste de Tukey, com nível de significância de 5%. Nenhuma diferença estatisticamente significante foi observada nos valores de microdureza Vickers, dos terços cervical, médio e apical do canal radicular, para o cimento resinoso químico (G1), e os terços cervicais do cimento resinoso dual, para todos os aparelhos fotopolimerizadores (G2, G3 e G4) (p>0.05). Porém, o aparelho de luz halógena (G2) e o LED UltraLume 5 (G4) apresentaram comportamentos semelhantes, proporcionando uma diminuição gradativa nos valores médios de microdureza do cimento resinoso dual, do terço cervical para o apical (p<0.001). Para o LED Radii (G3), essa diminuição foi observada apenas entre os terços cervical e médio (p<0.001). Entre os terços médio e apical, não houve evidência de diferenças significativas na microdureza superficial (p>0.05), e foram estatisticamente maiores que as restantes do cimento RelyX ARC nos terços correspondentes, fotopolimerizados pela luz halógena e LED UltraLume 5, demonstrando uma melhor profundidade de polimerização que os demais aparelhos avaliados. Os menores valores de microdureza foram encontrados nos terços apical do sistema RelyX ARC fotopolimerizado com luz halógena ou com LED UltraLume 5

This study evaluated the Vickers microhardness of a chemically cured resin cement (C&B Cement ­ Bisco) and a dual cure cement (RelyX ARC ­ 3M ESPE), light cured by different light sources, according to the different root canal depths, for luting of glass fiber posts. The light curing units employed were Optilux 360 (Demetron) ­ halogen lamp; Radii (SDI) - LED; UltraLume 5 (Ultradent) ­ LED. Forty roots of bovine mandibular central incisors were submitted to root canal treatment before luting of glass fiber posts Reforpost n. 3 (Ângelus) and were divided into four groups with ten roots each, according to the resin cement and light curing unit employed for post luting: G1) All Bond 2 / C&B Cement, without light curing (control); G2) Scotchbond Multipurpose Plus (SBMP) + RelyX ARC, light cured by halogen lamp; G3) SBMP + RelyX ARC, light cured by LED Radii; G4) SBMP + RelyX ARC, light cured by LED UltraLume 5. After 24- hour storage in distilled water at 370 C, the roots were transversely sectioned at three different depths: 3.0mm; 6.0mm and 9.0mm, corresponding to the cervical, middle and apical root canal third. Vickers microhardness measurements were achieved at 48 hours after luting, by 12 indentations on each root section, at the central portion of cement around the post, with a 200-g load for 20 seconds. Microhardness measurements were submitted to analysis of variance and to the Tukey test at a significance level of 5%. No statistically significant difference was observed in Vickers microhardness values at the cervical, middle and apical root thirds for the chemically cured resin cement (G1), and at the cervical third for the dual resin cement, for all light curing units (G2, G3 and G4) (p>0.05). However, the halogen lamp unit (G2) and LED UltraLume 5 (G4) presented similar performance, providing gradual reduction in mean microhardness values for the dual resin cement from the cervical to the apical third (p<0.001). Concerning the LED Radii (G3), this reduction was observed only between the cervical and middle thirds (p<0.001). There were no significant differences in surface microhardness between the middle and apical thirds (p>0.05), which were statistically higher than the others for the cement RelyX ARC at the corresponding thirds, light cured by halogen lamp and LED UltraLume 5, demonstrating better curing depth than the other units. The lowest microhardness values were found at the apical third for the system RelyX ARC light cured with halogen lamp or LED UltraLume 5